He sinh thai rung tu nhien Viet Nam

8/7/2019 He sinh thai rung tu nhien Viet Nam

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B NNG NGHIP V PHT TRIN NNG THN

CHNG TRNH H TRNGNH LM NGHIP & I TC

CM NANG

NGNH LM NGHIP

Chng

H SINH THI RNG TNHIN VIT NAM

NM 2006


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Bin son:

Phng Ngc LanPhan Nguyn HngTriu Vn Hng

Nguyn Ngha Thn

L Trn Chn

Chnh l:

Nguyn Vn TV Vn M

Nguyn Hong NghaNguyn B NgiTrn Vn Hng Quang Tng

H Trk thut v ti chnh: D n GTZ-REFAS


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Mc lc ......................................................................... Error! Bookmark not defined.

1. Tnh a dng ca h sinh thi rng tnhin Vit Nam ........................................5

1.1. a dng h sinh thi rng ............................................................................................51.2. a dng sinh hc ca h sinh thi rng Vit Nam.....................................................8

2. Cc nhm nhn t sinh thi pht sinh (phytooecogenetic factors) h sinh thirng tnhin Vit Nam............................................................................................8

2.1. Nhm nhn ta l - a hnh .....................................................................................82.2. Nhm nhn t kh hu, thu vn ...............................................................................102.3. Nhm nhn t m, th nhng .............................................................................122.4. Nhm nhn t khu h thc vt ..................................................................................132.5. Nhm nhn t sinh vt v con ngi.........................................................................15

3. Nhng h sinh thi rng tnhin ch yu Vit Nam .......................................20

3.1. H sinh thi rng kn thng xanh ma m nhit i............................................20

3.1.1. Phn b................................................................................................................203.1.2. iu kin sinh thi ..............................................................................................203.1.3. Cu trc rng ......................................................................................................203.1.4. Ti sinh v din th rng ....................................................................................293.1.5. ngha kinh t, phng h v khoa hc ..............................................................35

3.2. H sinh thi rng kn na rng l m nhit i ......................................................363.2.1. Phn b................................................................................................................363.2.2. iu kin sinh thi ..............................................................................................363.2.3. Cu trc rng ......................................................................................................363.2.4. Ti sinh v din th rng ....................................................................................383.2.5. ngha kinh t, phng h v khoa hc ..............................................................42

3.3. H sinh thi rng l rng thng xanh trn ni vi...........................................433.3.1. Phn b................................................................................................................433.3.2. iu kin sinh thi ..............................................................................................433.3.3. Cu trc t thnh thc vt...................................................................................453.3.4. Khu hng vt ni vi.................................................................................533.3.5. Ti sinh v din th rng ....................................................................................543.3.6. ngha kinh t, phng h v khoa hc ..............................................................55

3.4. H sinh thi rng l kim tnhin .............................................................................553.4.1. Phn b................................................................................................................553.4.2. iu kin sinh thi ..............................................................................................563.4.3. Cc loi h sinh thi rng l kim t nhin ..........................................................56

3.4.4. ngha kinh t, phng h v khoa hc ..............................................................593.5 H sinh thi rng tha cy h du (rng khp, dry dipterocarp forest) ...............603.5.1. Phn b................................................................................................................603.5.2. iu kin sinh thi ..............................................................................................603.5.3. Cu trc rng ......................................................................................................613.5.4. Ti sinh v din th rng ....................................................................................643.5.5. ngha kinh t, phng h v khoa hc ..............................................................65

3.6. H sinh thi rng ngp mn ......................................................................................65


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3.6.1. Phn b................................................................................................................653.6.2. iu kin sinh thi v qun th cy ngp mn....................................................673.6.3. Khu h thc vt rng ngp mn..........................................................................763.6.4. Khu hng vt rng ngp mn.........................................................................763.6.5. Ti sinh v din th rng ....................................................................................773.6.6. Khai thc hp l v s dng bn vng rng ngp mn .......................................79

3.6.7. ngha kinh t, phng h v khoa hc ..............................................................803.7. H sinh thi rng trm (Melaleuca cajuputi)...........................................................81

3.7.1. Phn b................................................................................................................813.7.2. iu kin sinh thi ..............................................................................................813.7.3. Cu trc rng ......................................................................................................833.7.4. Ti sinh v din th rng ....................................................................................843.7.5. ngha kinh t, phng h v khoa hc ..............................................................85

3.8. H sinh thi rng tre na (Bambusa spp) ................................................................853.8.1. Khi qut v rng tre na ...................................................................................853.8.2. H sinh thi rng lung (Dendrocalamus barbatus) ...........................................903.8.3. H sinh thi rng vu..........................................................................................96

3.8.4. H sinh thi rng na..........................................................................................983.8.5. H sinh thi rng l (Bambusa balcoa Roxb.)...............................................100


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1. Tnh a dng ca h sinh thi rng tnhin Vit Nam

1.1. a dng h sinh thi rnga) iu kin sinh thi c nh hng quyt nh n tnh a dng ca h sinh thi rng

Vit Nam. Lnh th lc a tri di t vtuyn 23o 24 B n vtuyn 8o 35 B, nm trong vnh ainhit i bc bn cu tip cn gn vi xch o.Vit Nam c kh hu nhit i gi ma c mang lnhv cn xch o. Bbin di 3.260 km t Mng Ci n H Tin, ni c rng ngpmn, ni c rng phi lao trn ct.

i ni chim ba phn t lnh th, t vng ven bin n ng bng, trung du, caonguyn, vng ni vi nh ni cao nht l Phan Xi Png cao 3.143 m. Chnh iu kin a hnhny lm cho Vit Nam khng ch c kh hu nhit i gi ma m cn c c kh hu nhiti v n i ni cao. Khng k min kh hu bin ng, kh hu lc a c 3 min kh hu (phaBc, ng Trng Sn, pha Nam) vi 10 vng kh hu c trng cho cc vng sinh thi khcnhau. iu kin a hnh v kh hu trn y to nn nhiu qu trnh hnh thnh t khc nhau.Vit Nam khng ch c nhng lp t nhit i in hnh nht Feralit, t nu v t en nhiti v.v m cn c c lp t nhit i, lp t ph nhit i vng ni v ct vng altptzn ho trn ni cao.

b) Tnh a dng v loi cy v ng vt l mt trong nhng nhn t quyt nh tnh adng v h sinh thi rng t nhin ca Vit Nam. V khu h thc vt, ngoi nhng yu t bn ac hu, Vit Nam cn l ni hi t ca 3 lung thc vt di c t Trung Quc, n - Himalaya, Malaixia - Innxia v cc vng khc k c n i.

Theo Nguyn Ngha Thn (1997), nc ta c khong 11.373 loi thc vt thuc 2524 chiv 378 h. Cc nh thc vt hc don con s loi thc vt nc ta cn c th ln n 15.000loi. Trong cc loi cy ni trn c khong 7.000 loi thc vt c mch, s loi thc vt c huca Vit Nam chim khong 30% tng s loi thc vt min Bc v chim khong 25% tng sloi thc vt trn ton quc (L Trn Chn, 1997), c t nht 1.000 loi cy t kch thc ln,354 loi cy c th dng sn xut g thng phm. Cc loi tre na Vit Nam cng rt

phong ph, trong c t nht 40 loi c gi tr thng mi. S phong ph v loi cy mangli cho rng Vit Nam nhng gi tr to ln v kinh t v khoa hc. Theo thng k ca Vin Dcliu (2003), hin nay pht hin c 3.850 loi cy dng lm dc liu cha bnh, trong cha c c nhng bnh nan y him ngho. Theo thng k ban u, pht hin c 76 loicy cho nha thm, 600 loi cy cho tananh, 500 loi cy cho tinh du v 260 loi cy cho dubo.

Vng vt, theo ng Huy Hunh (1997), nc ta c khong 11.050 loi ng vt baogm 275 loi v phn loi th, 828 loi chim (nu tnh c phn loi th khu h chim nhit inc ta ln n 1.040 loi v phn loi), 260 loi b st v 82 loi ch nhi, khong 7.000 loicn trng v hng nghn loi ng vt t, c bit c nhiu t rng v.vTheo t liu caIUCN/CNPPA (1986) khu hng vt Vit Nam kh giu v thnh phn loi v c mc cao

v tnh c hu so vi cc nc trong vng phng Dng. Trong s 21 loi kh c trong vngph ny th Vit Nam c 15 loi, trong c 7 loi v phn loi c hu (Eudey 1987) .TheoMackinon, trong vng ph c 49 loi chim c hu th Vit Nam c 33 loi trong c 10loi c hu ca Vit Nam.

c) H thng phn loi h sinh thi rng Vit Nam

Thi Vn Trng (1978, 1999) cn c vo quan im sinh thi pht sinh qun th thcvt phn loi thm thc vt rng Vit Nam. T tng hc thut ca quan im ny l trongmt mi trng sinh thi c th ch c th xut hin mt kiu thm thc vt nguyn sinh nht


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nh. Trong mi trng sinh thi , c 5 nhm nhn t sinh thi pht sinh nh hng quyt nhn t thnh loi cy rng, hnh thi, cu trc v hnh thnh nn nhng kiu thm thc vt rngtng ng. Cn c vo csl lun trn, Thi Vn Trng phn loi thm thc vt rng VitNam thnh 14 kiu thm thc vt c trn t lm nghip nh sau:

Cc kiu rng, rng kn vng thp:

I. Kiu rng kn thng xanh, ma m nhit i

II. Kiu rng kn na rng l, m nhit i

III. Kiu rng kn rng l, hi m nhit i

IV. Kiu rng kn l cng, hi kh nhit i

Cc kiu rng tha:

V. Kiu rng tha cy l rng, hi kh nhit i

VI. Kiu rng tha cy l kim, hi kh nhit i

VII. Kiu rng tha cy l kim, hi kh nhit i ni thp

Cc kiu trng trung:VIII. Kiu trng cy to, cy bi, c cao kh nhit i

IX. Kiu trung bi gai, hn nhit i

Cc kiu rng kn vng cao:

X. Kiu rng kn thng xanh, ma m nhit i ni thp

XI. Kiu rng kn hn hp cy l rng l kim, m nhit i ni thp

XII. Kiu rng kn cy l kim, m n i m ni va

Cc kiu qun h kh lnh vng cao:

XIII. Kiu qun h kh vng caoXIV. Kiu qun h lnh vng cao

Trong mi kiu thm thc vt li chia thnh cc kiu ph min (ph thuc vo t thnhthc vt), kiu ph th nhng (ph thuc vo iu kin t), kiu ph nhn tc (ph thuc votc ng ca con ngi) v trong mi kiu ph tu theo u th ca loi cy m hnh thnhnn nhng phc hp, u hp v qun hp t nhin khc nhau. Nh vy, bc tranh h sinh thirng nc ta rt a dng v phong ph.

Nm 1970, Trn Ng Phng cng xut bng phn loi rng min bc Vit Nam. ngphn loi rng min bc thnh 3 ai rng:

A. ai rng nhit i ma ma:1. Kiu rng nhit i l rng thng xanh ngp mn

2. Kiu rng nhit i ma ma l rng thng xanh

3. Kiu rng nhit i m l rng thng xanh

4. Kiu rng nhit i l rng thung lng

5. Kiu rng nhit i l rng thng xanh ni vi


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B. ai rng nhit i ma ma:

1. Kiu rng nhit i l rng thng xanh

2. Kiu rng nhit i l kim trn ni vi

3. Kiu rng nhit i l kim trn ni t

C. ai rng nhit i ma ma ni cao

ai ny c 3 loi hnh: P mu ( Fokienia hodginsii), Sa mc (Cunninghamialanceolata), quyn (Rhododendron simsii).

Theo thang phn loi ca UNESCO (1973), thm thc vt nc ta c 4 l p qun h,trong c 2 lp qun h c lin quan n rng l: rng rm v rng tha. Mi lp qun h lichia thnh cc phn lp, mi phn lp li chia thnh cc nhm qun h v sau mi n ccqun h. Mi qun h li c chia thnh cc phn qun h v di l qun hp. Cn c vonguyn tc phn loi nh trn, thm thc vt rng Vit Nam c phn loi nh sau:

I. Lp qun h 1: Rng rm

Lp qun h ny gm 3 phn lp qun h chnh l: rng thng xanh, rng rngl v rng kh.

1. Phn lp qun h rng thng xanh nhit i:

a) Nhm qun h rng ma thng xanh

b) Nhm qun h rng ma ma thng xanh:

Rng t thp

Rng ni thp

Rng ni va

Rng ni cao

Rng ni vi thp

Rng ni vi trung bnh

Rng bi ct ven bin

Rng trn t ph sa

Rng ngp nc

Rng s vt

Rng thng trn ni thp

Rng tre na trn ni thp

c) Nhm qun h rng na rng l nhit i:

Rng na rng l nhit i trn t thp

Rng na rng l nhit i trn ni thp

Rng na rng l nhit i trn ni vi

Rng na rng l nhit i trn ni cao trung bnh


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2. Phn lp qun h rng rng l nhit i

3. Phn lp qun h rng kh nhit i

a) Nhm qun h rng l cng kh

b) Nhm qun h rng gai:

Rng gai na rng l

Rng gai rng l

II. Lp qun h 2: Rng tha

Lp qun h ny c 3 phn lp qun h:

1. Phn lp qun h rng tha thng xanh:

a) Nhm qun h rng tha l rng:

Rng trn t thp

Rng trn ni thp

b) Nhm qun h rng l kim2. Phn lp qun h l rng rng l vng ni v vng t thp

3. Phn lp qun h rng tha kh:

a) Nhm qun h rng tha l cng kh

b) Nhm qun h rng tha c gai:

ng gai na rng l

* Rng gai thng xanh

Phn loi thm thc vt rng ca Thi Vn Trng, Trn Ng Phng v UNESCO

khng nh tnh a dng ca h sinh thi rng Vit Nam.1.2. a dng sinh hc ca h sinh thi rng Vit NamDo tc hi ca ph rng nn tnh a dng sinh hc ca rng nhit i Vit Nam ang

trong qu trnh suy gim. Nhiu loi thc vt rng qu him ang be do c nguy c tuytchng nh: Bch xanh, Thu tng, Thng hai l dt v.v Khng ch nhng loi cy g ln mc nhiu loi cy lm sn ngoi g nh cc loi cy lm thuc cha bnh (dc liu): Sa nhn,H th , Sm Ngc Linh v.v cng ngy cng cn kit. ng vt rng cng ang him dn.Nhiu loi ng vt rng qu him cng ang be do tuyt chng nh T gic mt sng, Bxm, H, Voi v.vNhiu h sinh thi rng nhit i nguyn sinh ang b khai thc lu. Phn lnrng cn li hin nay l rng th sinh ngho. Bo v rng l bin php cbn quyt nh n

vic bo tn tnh a dng sinh hc ca cc h sinh thi rng nhit i Vit Nam.2. Cc nhm nhn t sinh thi pht sinh (phytooecogenetic factors) h sinh thi rng t

nhin Vit Nam

2.1. Nhm nhn ta l - a hnhNhm nhn ta l a hnh bao gm nhng nhn t hnh thnh trong lch s kin to

ca Tri t qua cc ki a cht v quyt nh s phn phi ca hi dng v lc a, shnh thnh a hnh, a mo v thnh phn a cht ca v Tri t.Tuy nhm nhn ta l ahnh khng nh hng trc tip n cc kiu thm thc vt, nhng chng l nhng nhn t c tc


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dng chi phi nh hng ca nhng nhm nhn t khc nh kh hu thu vn, m th nhngv khu h thc vt.

Nhm nhn ta l a hnh bao gm nhng nhn t sau y :

- vv kinh, c bit l vv n c nh hng ln n ch kh hu. Nhn tvhnh thnh nn vnh ai vc nh hng ln n kh hu v phn b thc vt trntri t.

- lc a l khong cch t vng n bin.- cao, hng phi, dc l nhng nhn t c nhiu nh hng n tiu kh hu. Nhn

t cao hnh thnh nn vnh ai cao c nh hng n kh hu v phn b thc vt.

- Nn tng m din ra qu trnh hnh thnh t.S bin ng nhit theo vv cao c tnh tng ng v hnh thnh nn hin

tng "song hnh sinh hc", t dn n s tng ng v phn b thc vt theo vv cao. Xut pht t quan im ny, Thi Vn Trng (1978, 1999) phn chia thm thc vt trongmt vng thnh hai nhm ln: nhm cc qun ththc vt theo vv nhm cc qun ththcvt theo cao.

Trong iu kin Vit Nam, gii hn vnh ai nhit i vng ni thp min Bc l 600- 700 m, min Nam l 1.000m do min Nam gn xch o hn min Bc.

Nhm nhn ta l a hnh nc ta c nh hng quyt nh n kh hu v thm thcvt nh sau:

- Tnh cht c xa ca lch s kin to a cht l ngun gc khin cho nhng kiu thmthc vt nguyn thu vn cn tn ti, in hnh nht l rng nguyn sinh Cc Phng(Ninh Bnh) vi ng ngi xa. Ngoi ra, nhng loi tn di (Reliques) tng xut hint nhng thi k rt c xa.


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Hnh s 1. Nhm nhn t sinh thi pht sinh a l- a hnh

(theo Thi Vn Trng )

Nhng hin nay vn ang cn st li nh nhng loi cy trong cc chi Cycas, Ducampopinus,Fokienia, Libocedrus, Glyptostrobus v.v

- a hnh i ni chim n ba phn t lnh th.- H thng ni ca Vit Nam l s ko di t h thng ni min nam Trung Quc v chn

dy ni Himalaya. H thng ni non trong nc ko di lin tc t bc vo nam. Nhngiu kin trn y to iu kin thun li cho cc lung di c thc vt t vng nhiti v c n i vo lnh th Vit Nam. Chnh v vy m h thc vt Vit Nam rt adng v phong ph v loi cy.

- Hng u th ca a hnh l hng Ty Bc - ng Nam, hng ny li vung gc vihng gi ma ng Bc ngn cn bt khng kh lnh t pha Bc trn v.

- Mt ct ngang ca dy Trng Sn khng i xng, sn ty th dc thoai thoi ko din lu vc sng M Kng, cn sn ng li c dc cao v tip cn ngay vi bbin. Do vy, nhng h sinh thi rng dy Trng Sn c ngha phng h cc k quantrng cho vng ven bin Trung B.

- Do tnh him trca h thng ni vi ca Vit Nam nn hin nay vn cn c mt hsinh thi rng nhit i c bit m khng phi nc no cng c.

- Do h thng ni non him trvi nh ni cao nht l Phan Xi Png (3143 m) v do VitNam ko di hn 15 vnn gii hn di ca vnh ai nhit i vng ni thp tngdi hai min nam bc khc nhau. Gii hn ny min Bc l 600 - 700 m, minNam l 1.000 m. y cng l ranh gii phn bit cc h sinh thi rng Vit Nam theo

cao.

2.2. Nhm nhn t kh hu, thu vnNhm nhn tkh hu thu vn l nhm nhn t cho quytnh hnh dng v cu

trc ca cc kiu thm thc vt(Aubreville, 1949). Trong nhm nhn t kh hu thu vn vngnhit i th nhn tnhit c nh hng khng ch thm thc vt nhng vng ni cao, cnnhn t nh sng li nh hng n i sng ca cc thc vt sng di tn rng, c bit l tisinh rng v din th rng. Tuy nh sngkhng gy nh hng trc tip n vic hnh thnh cc


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kiu thm thc vt trc mt nhng thng qua nh hng ca nh sng n ti sinh v din thrng m hnh thnh nn nhng h sinh thi rng c t thnh loi thc vt khc nhau. Nhn tginh hng n ch kh hu, c bit ch gi ma c nh hng trc tip n nhit ,lng ma, s phn phi lng ma v ch kh hn.

Trong nhm nhn t kh hu thu vn, ch kh m l tc nhn khng ch quyt nh shnh thnh nhng kiu kh hu nguyn sinh ca thm thc vt thin nhin trn mt vng ln

min nhit i gi ma. Ch kh m l mt phc h bao gm lng ma hng nm, chskhhn v m trung bnh thp nht.

Ch s kh hn (X) c xc nh theo cng thc sau:

X = S . A . D

trong :

- S l s thng kh: thng kh l thng c lng ma tnh bng mm nh hn hoc bng hailn nhit trung bnh thng.

- A l s thng hn: thng hn l thng c lng ma nh hn hoc bng mt ln nhit trung bnh thng.

- D l s thng kit: thng kit l thng c lng ma trung bnh hng thng xp x bng 0.y l nhng thng khng c ma hoc lng ma rt t di 5 mm.

Nh vy, ch cn bit lng ma v nhit trung bnh thng l c th xc nh cthng kh, hn hay kit.

V lng ma, c 5 cp sau y:

- C p I: lng ma trung bnh hng nm trn 2.500 mm thuc loi ma m. y l lngma m kiu thm thc vt rng kn thng xanh l rng c hnh thnh v tn ti trongbt k hon cnh no.

- C p II: lng ma trung bnh hng nm t 1.200 mm - 2.500 mm thuc loi m v him

- Cp III: lng ma trung bnh hng nm t 600mm - 1.200 mm thuc loi hi kh vkh.

- Cp IV: lng ma trung bnh hng nm t 300mm - 600 mm thuc loi hn- Cp V: lng ma trung bnh hng nm di 300 mm thuc loi cc hn

Nhm nhn t kh hu thu vn l cs phn loi kiu thm thc vt kh hu. lkiu thm thc vt m s hnh thnh pht sinh pht trin ca n chu nh hng quyt nh biiu kin kh hu.

Kh hu Vit Nam l kh hu nhit i gi ma. Ch gi ma c nh hng quyt nhchi phi n kh hu thi tit c nm. Gi ma ng Bc chuyn khng kh lnh t phng bc.Gi ma Ty Nam i qua vng bin a ma m vo lc a. Hng nm c mt ma ma voma h nng v mt ma kh vo ma ng gi lnh. Vng Bc Trung B cn chu nh hngca gi Lo kh nng, tc ng trc tip n i sng thc vt. c bit, Vit Nam cn chu nhhng trc tip ca bo t bin ng i vo lc a gy ra nhng bin ng mnh v thi tit khhu nht l ch ma bao gm lng ma ln v cng ma mnh.

Ch nhit Vit Nam cng khc nhau gia hai min Nam, Bc v theo cc ai caokhc nhau. Kh hu min Nam mang tnh cht nhit i chun, khng c ma ng lnh, tr mt


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vi vng cc nam kh hu mang tnh cht cn xch o. Kh hu min Bc mang tnh cht nhiti nhiu hn v c mt ma ng gi lnh bt thng.

Ch nhit vng ni thay i theo cao. Cng ln cao nhit cng gim. Chnh vvy, vng ni cao cng xut hin nhng loi, chi, h thc vt vng nhit i v n i. Yut cao trong a hnh c nh hng n phn b cc loi thc vt rng nh sau:

- Vnh ai cao t 700m - 1.600m (min Bc) v t 1.000m - 1.800m (min Nam) lvnh ai cao nhiti ni thp tng di. Nhit trung bnh hng nm t 15 - 20oC, nhit ti thp tuyt i c khi xung n 0 oC, xut hin sng mui.

T thnh thc vt vng ni pha bc c nhng h thc vt nhit i chim u th rrt nh h D (Fagaceae), h Re (Lauraceae), h Ch (Theaceae), h Du (Ulmaceae), h Mclan (Magnoliaceae), h c ch (Juglandaceae), h Hoa hng (Rosaceae) v.v Trong vnh ainy t thy nhng loi cy ca kh hu nhit i vng thp v vng c cao trung bnh nh hDu (Dipterocarpaceae), cy sng l hoc bng lng (Lagerstroemia calyculata Kurz) v.vNgoi ra cn thy xut hin loi du sam (Keteleeria davidiana)

T thnh thc vt vnh ai cao ny min Nam c loi thng ba l (Pinus kesiya)

-

Vnh ai cao t 1.600 m - 2.400 m (min Bc) v t 1.800 m - 2.600 m (min Nam)l vnh ai n i m ni thp tng trn. Nhit trung bnh hng nm t 10o C - 15oC,nhit trung bnh thng lnh nht di 10oC, nhit ti thp tuyt i xung di 0oC.Thc vt y c nhng loi cy ca vng n i m thuc cc chi nh: Alnus, Betula,Acer, Carpinus v.vNhng loi cy ny hn giao vi nhiu loi cy l kim thuc cc chinh Dacrydium, Libocedrus, Cephalotaxus, Fokienia v.v min Nam, y l vnh ai cao xut hin loi thng nm l Lt (Pinus dalatensis) v c bit l loi thng ldt (Ducampopinus krempfii), mt loi cc hu Vit Nam pht hin c pha namdy Trng Sn.

- Vnh ai cao trn 2.400 m (min Bc) v trn 2.600 m (min Nam) l vnh ai ni lnh ni va tng di. Vnh ai ny c tuyt ph trong ma ng. Nhng kt qu

nghin cu v vnh ai cao ny cn rt t.Ch kh m Vit Nam ph thuc nhiu vo ch gi ma, c nhng thay i mang

tnh a phng do hng phi ca a hnh v bbin quyt nh. V vy, lng ma hng nmbin ng nhiu qua cc vng sinh thi khc nhau, c vng lng ma trung bnh rt ln trn4.000 mm/nm nhng cng c vng kh hn ca min bn hoang mc nh vng Phan Ranglng ma trung bnh nm l 757 mm, lng ma trung bnh nm thp nht 413 mm, c nmlng ma th p nht tuyt i ch c 272 mm/nm. min Bc, vng An Chu (Bc Giang),Mng Xn (Ngh An), Pha in, C Ni (Lai Chu) cng c ch hn kit do lng ma thpv ma kh ko di gay gt.

Nhm nhn t kh hu thu vn c nh hng quyt nh n vic hnh thnh cc kiu

thm thc vt kh hu nguyn sinh Vit Nam.2.3. Nhm nhn t m, th nhng

m th nhng l nhm nhn t tham gia tc ng trong qu trnh pht sinh pht trincc kiu thm thc vt. Trn nhng loi hnh ta i hon ton thnh thc shnh thnh phtsinh nhng kiu thm thc vta i. Tuy nhin, nu nhng bin i t bin ca ch mam lm nh hng n l tnh ca t th s xut hin nhng kiu thm thc vt m Thi VnTrng (1978, 1999) gi l kiu ph th nhng kh hu nh rng tha, trng c, trung gaiv.vNu qu trnh a i pht sinh th nhng khng hon chnh s to nnt phi a i


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hoc t ni a i. Trn nhng loi t ny s hnh thnh pht sinh kiu ph thnhngc tthnh loi cy c bit khc vi cc kiu thm thc vt kh hu trong vng nht ni vi, trng ngp mn v.vTrn t Feralit thoi ho c tng ong cht cng hnh thnh nn nhngkiu thm thc vt thoi ho khng hi nguyn c trng thi ban u. Nhng kiu ph nychnh l loi hnh ni a i ca thm thc vttrn t phn, t ngp, t ly v.v... Nhng loihnh ny, t thnh loi cy, cu trc hnh thi ca qun th s c nhng c trng khc hn vi

nhng kiu thm thc vt kh hu. Nh vy, nhm nhn t m th nhng tc ng n qutrnh pht sinh cc kiu thm thc vt v hnh thnh nn nhng kiu thm thc vt thnhngkh hu v kiu thm thc vt ph thnhng.

2.4. Nhm nhn t khu h thc vtKhu h thc vt l nhm nhn t tham gia vo qu trnh pht sinh cc kiu thm thc vt.

Trong thc t c nhiu trng hp, tuy iu kin kh hu v t hon ton ging nhau nhng lixut hin nhng kiu thm thc vt khc nhau v t thnh loi cy. Gii thch iu ny phi davo nhm nhn t khu h thc vt. Theo quan im a l thc vt th khu h thc vt mt vngbao gm cc thnh phn thc vt bn a c hu (k cc hu c v c hu mi) v cc thcvt ngoi lai t cc lung thc vt di c t ni khc n. Tu theo iu kin a hnh, hnh thc

pht tn ca thc vt (nhgi, nc v.v) v kh nng thch nghi ca thc vt m t l tham giaca cc loi thc vt ngoi lai vo khu h thc vt a phng khc nhau. S tham gia ca cclung thc vt di c hnh thnh nn nhng kiu thm thc vt c thnh phn loi cy khc vicc kiu thm thc vt kh hu. Thi Vn Trng (1978, 1999) gi y l " kiu ph min thc vt". y cng l loi hnh ni a i ca thm thc vtdo nh hng ca t l v thnh phn loicy trong khu h thc vt bn a c hu v cc yu t thc vt ngoi lai di c t ni khc n.Trong nhng trng hp ny, cc kiu ph min thc vt c t thnh, hnh thi, cu trc qun thkhc nhau.

Trong iu kin, di nh hng ca kh hu hnh thnh nhng loi t a i nhngdo nh hng ca tiu a hnh, vi a hnh, hng phi, dc m hnh thnh nn nhng tiukh hu, th nhng c bit. Ti y, xut hin nhng kiu thm thc vt khc hn vi cc kiu

thm thc vt a i. Nhng kiu thm thc vt ny c gi l kiu tri . Tuy nhin, nhngkiu tri ny thng ch xut hin trn phm vi hp.

Khu h thc vt Vit Nam, ngoi thnh phn bn a c hu cn c cc thnh phn di cbao gm ba lung thc vt di c chnh v mt s nhn t di c khc.

- Lung thc vt di c t Malaixia - Indnxia.i din cho lung di c ny l cc loi cy thuc h Du (Dipterocarpaceae) xut pht t

trung tm pht sinh o Bocneo. Colani tm thy g ho thch v du vt l ca rng du lu vc sng a Hng, min nam Vit Nam. iu ny chng t nhng loi cy h Du di cn Vit Nam t k tam. Nhng loi cy trong h Du bao gm c nhng loi cy thng xanhv mt s loi cy rng l thch nghi vi nhng vng kh hn, hnh thnh nn rng tha cyh Du, in hnh l rng khp c Lc, Gia Lai v.v

- Lung thc vt di c t vng n i theo v(Vn Nam- Qu Chu) v vng ai n ini va thuc dy ni Himalaya.

Lung thc vt di c ny bao gm cc loi cy l kim ca ngnh ph ht trn(Gymnospermae) nh Pinus merkusii, Pinus kesiya, Keteleeria davidiana, Fokienia hodginsii,Libocedrus macrolepis, Tsuga yunnanensis, Abies pindrow, Cryptomeria japonica v.v... Ngoi racn c cc loi cy l rng, rng l trong ma ng thuc h D (Fagaceae),h Hoa (Betulaceae),h Thch (Aceraceae), h liu (Oleaceae), h c ch (Juglandaceae), h quyn


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(Ericaceae),h Ch nem (Vacciniaceae). Cc loi cy thuc lung di c ny thng xut hin chyu vng ni cao v ni va.

- Lung thc vt di c t vng kh hn ca n - Myanma.

i din cho lung di c ny l h Bng (Combretaceae) trong phn ln cc loi thuccc chi Terminalia, Anogeissus, Finetia, Combretum c c im rng l trong ma kh. Ngoira cn c nhng loi cy rng l nh Tch (Tectona grandis), Li th (Gmelina arborea) trongh Verbenaceae, Tung (Tetrameles nudiflora) trong h Datiscaceae, Sng l hay Bng lng(Largerstroemia sp) trong h Lythraceae, Go (Cossampinus malabaricus) trong hBombacaceae v.vCc loi thc vt thuc lung di c ny di c vo vng ni cao Ty BcVit Nam v dc theo dy Trng Sn i n cc cao nguyn Ty Nguyn.


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Theo Thi Vn Trng (1978, 1999), c lng thnh phn cc nhn t bn a v ngoi lai trongkhu h thc vt Vit Nam nh sau:

Nhn t bn a c hu:

(Khu h Bc Vit Nam - Nam Trung Hoa) 50%

Nhn t di c:

T khu h thc vt Malaixia - Indonexia 15%

T khu h thc vt Himalaya - Vn Nam - Qu Chu 10%

T khu h thc vt n - Myanma 14%

Cc nhn t khc:

Nhit i khc 7%

n i 3%

Th gii 1%

Tng cng 100%

(Khng k cc loi cy nhp ni)

Thnh phn khu h thc vt trn y lm tng tnh a dng v loi v h sinh thi chothm thc vt rng Vit Nam.

2.5. Nhm nhn t sinh vt v con ngiNhm nhn t ny bao gm nhng tc ng ca sinh vt v con ngi n h sinh thi

rng, k c tc ng tiu cc v tch cc. Nhng h sinh thi rng nguyn sinh, khi b sinh vt vcon ngi tc ng s din ra mt qu trnh din th th sinh. Nhng h sinh thi ny c hnhthi, cu trc v c t thnh loi cy khc hn vi nhng h sinh thi nguyn sinh ban u. Nhmnhng h sinh thi ny c gi l kiu ph sinh vt nhn tc. y cng l loi hnh qun thphia i khng ging vi cc qun th nguyn sinh ngay c trong cng mt iu kin a l ahnh, kh hu, t v khu h thc vt tng t.

Con ngi vi t cch l ch th va c tc ng tch cc v tiu cc n h sinh thirng. Gy trng rng nhn to l hot ng tch cc ca con ngi. Nhng qun th nhn to nyc xp vo kiu ph nui trng nhn to. Ngoi nhng qun th thc vt nhn to thun loi tthnh bi nhng loi cy nhp ni, dn ging t nhng vng sinh thi khc k c t nc ngoicn c mt s loi cy bn a c hu. Nhng qun th ny c t thnh loi cy, hnh thi cu

trc hon ton khc vi cc qun th thc vt a i.Tuy nhin, trong qu trnh tn ti v pht trin, con ngi cng c nhiu tc ng tiu

cc n h sinh thi rng di cc hnh thc khc nhau. Chnh nhng tc ng ny dn nqu trnh din th th sinh ca h sinh thi rng nguyn sinh. Do vy, nhng qun th rng thsinh hnh thnh di tc ng ca con ngi c gi l kiu ph thsinh nhn tc. Tc ngca con ngi n rng c th c ba hnh thc sau y :

- t rng lm ry trng cy nng nghip- Khai thc lm sn lm thay i t thnh loi cy, ph vcu trc hnh


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- thi qun th ban u.- Chin tranh, cht c ho hc v.v

Nu tc ng ph hoi ca con ngi khng c ngn chn m vn tip tc t rng lmry v khai thc lm sn qu mc lp li nhiu ln th khng ch thnh phn thc vt b xo trnm t rng cng b thoi ho, cn ci lm cho rng khng th tn ti c v bin thnh trngcy bi, trng c. Nhng h sinh thi ny khng ch chu s tc ng trc tip ca con ngi mcn chu tc ng ca iu kin th nhng thoi ho. Do vy, nhng qun th rng ny cxp vo kiu ph thnhng nhn tc. y nhn t th nhng tr thnh nhn t quyt nhlm cho qun th thc vt rng khng th din th phc hi li trng thi ban u.

Trong thc tin Vit Nam cn c tc ng ca con ngi thng qua chn nui gia sc vng trung du v min ni. Cc dn tc min ni c tp qun t c vo ma kh sang xunc non mc ln cho tru b n. y l nguyn nhn hnh thnh nn nhng ng c th sinh Vit Nam. Nhng qun th trong iu kin ny c gi l kiu ph sinh vt nhn tc. Kiu phny c hnh thnh di tc ng ca con ngi thng qua hot ng chn nui gia sc.

Kiu ph th sinh nhn tc c nhiu Vit Nam. Rng nguyn sinh ch cn li ccvn quc gia, khu bo tn thin nhin v nhng ni xa xi ho lnh, a hnh him tr. Nghin

cu kiu ph th sinh nhn tc rt c ngha thc tin i vi vic phc hi rng t nhin ncta. Kiu ph ny c th chia ra hai loi ln :

- Kiu thm thc vt hnh thnh trn t cn tnh cht t rng, t cha b thoi ho.Trong iu kin ny, qun th thc vt rng c kh nng phc hi, "hi nguyn" li trng

thi ban u thng qua mt qu trnh din th tin ho.

Nu thc hin lun canh nng ry, ch trng cy nng nghip trong thi gian ngn, trng cha thoi ho vn cn tnh cht t rng th rng vn cn c kh nng phc hi trong iukin rng c bo v nghim ngt. Din th th sinh bt u t ti sinh ca nhng loi cy tinphong a sng, mc nhanh, i sng ngn, g mm v nh nh Ba bt (Mallotus apelta), Hu nu(Mallotus cochinchinensis), Ba soi (Macaranga denticulata), B (Styrax tonkinensis), Mngtang (Litsea citrata), Na (Schizostachyum funghomii), Giang (Maclurochloa sp. ) v.v Cutrc ca h sinh


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Hnh s 2. Chy rng do con ngi

Hnh s 3. My bay M ri cht c ho hc trong chin tranh

thi ny n gin thun nht, t thnh phn ln l nhng loi cy a sng chim u th, c nign nh thun loi nh rng B (Styrax tonkinensis), Rng rng mt (Ormosia balansae),Cho (Engelhardtia chrysolepis) v.vTuy nhin, do i sng ca nhng loi cy tin phongthng ngn nn gi l loi cy tin phong tm thi. Ch tr mt s loi cy a sng c i sngdi mi c kh nng tn ti lu di trong qun th nh Sau sau (Liquidamba formasana), T hpin Bin (Altingia takhtajanii ), M(Manglietia conifera), v.v Nhng loi cy ny gi l loicy tin phongnh c.Nhng loi cy tin phong ny hnh thnh nn h sinh thi rng th sinhVit Nam do tc ng ca con ngi. Trong qu trnh din th tip theo, tu theo mc phctp ca t thnh loi cy m hnh thnh nn nhng phc hp, u hp v qun hp. Ch tiu phnbit ba loi hnh ny l u thca c thcc loi trong tng lp qun,

Phc hp (Complexion) l nhng qun th m u th ca cc loi cy cha phn hor rt. y l mt c trng cu trc t thnh ca rng ma nhit i ni chung v Vit Nam niring.

u hp (Dominion) l nhng qun th c s c th ca 10 loi chim 40 - 50% tng s cth trong tng lp qun, mi loi cy chim khong 4 - 5 % tng s c th. Vit Nam, nhngu hp ny xut hin nhiu trong cc h sinh thi rng t nhin nhu hp Sao en (Hopeaodorata), u hp Ch en (Parashorea stellata), u hp Ch nu (Dipterocarpus tonkinensis),u hp Du ri (Dipterocarpus alatus), u hp Tu (Vatica tonkinensis) v.v Ngoi cc u hploi ni trn cn c th xut hin u hp chi, u hp h. l nhng u hp c mt chi hocmt h chim u th.

Qun hp (Association) l nhng qun th gn nh thun loi, u th ca 1 - 2 loi cyrng chim 90% tng s c th trong tng lp qun. Trong iu kin nhit i, nhng qun hp


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xut hin khng mang tnh ph bin nh phc hp, u hp nhng khng phi l khng c. Th d: rng thng ba l thun loi trn ni cao, rng c (Rhizophora conjugata) rng ngp mnven bin. Lch s ghi li nhng khu rng lim xanh (Erythrophloeum fordii Olive) Hu Lng(Lng Sn), Qu Chu (Ngh An), rng Sao en (Hopeaodorata) thun loi t nhin L Lt (Nha Trang ) v.vNhng qun hp ny thng xut hin trong nhng iu kin c bit, khngphi l do mi trng sinh thi xu.

- Kiu thm thc vt hnh thnh trn t thoi ho khng cn tnh cht t rng.Trong iu kin ny, qun th thc vt ang nm trong qu trnh din th thoi ho,

khng th "hi nguyn" c trng thi ban u v rng s din th chch hng so vi rng banu.

y l trng hp qun th rng bt nng lm ry nhiu ln, rng b khai thc kitqu, t b thoi ho khng cn tnh cht t rng. Lp thc vt rng b thay th bi trng cybi, trng c th sinh. Trong nhng iu kin ny, h sinh thi rng ch c th phc hi bng gytrng rng nhn to.

Nh vy, cc bc phn loi kiu thm thc vt theo quan im sinh thi pht sinh nhsau:

- Nhm nhn ta l a hnh:Nhm cc qun th thc vt theo v

Nhm cc qun th thc vt theo cao

Gii hn vnh ai nhit i vng ni thp tng di min Bc l 600 - 700 m v min Nam l 1.000 m.

- Nhm nhn t kh hu - thu vnKiu thm thc vt kh hu

- Nhm nhn t m th nhngKiu thm thc vt th nhng kh hu

Kiu ph th nhng

- Nhm nhn t khu h thc vtKiu ph min

Kiu tri

- Nhm nhn t sinh vt v con ngiKiu ph gy trng nhn to

Kiu qun th th sinh nhn tcKiu ph th nhng nhn tc

Kiu ph sinh vt nhn tc

Cn c vo cc bc phn loi k trn, Thi Vn Trng phn loi thm thc vt VitNam thnh 14 kiu, trong c 10 kiu lin quan n qun th rng. Nhng n v phn loi nycha phi l n v phn loi cbn. Trong mi kiu thm thc vt li c nhiu kiu ph vinhiu phc hp, u hp, qun hp khc nhau. Do vy s c nhiu h sinh thi c th khc nhau.


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Di y ch gii thiu nhng h sinh thi rng t nhin ch yu, quan trng i vi snxut lm nghip.


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3. Nhng h sinh thi rng tnhin ch yu Vit Nam

3.1. H sinh thi rng kn thng xanh ma m nhit i3.1.1. Phn b

- Nhng h sinh thi rng thuc kiu thm thc vt ny rt phong ph v a dng, phn bcc tnh: Qung Ninh, Cao Bng, Lng Sn, Ph Th, Yn Bi, Tuyn Quang, Lo Cai,

Ninh Bnh (Cc Phng), Thanh Ho, Ngh An, H Tnh, Qung Bnh, Qung Tr, ThaThin Hu, Qung Nam, Ty Nguyn v.v

- Phn b theo cao so vi mc nc bin: min Bc: di 700 m

min Nam: di 1.000 m

3.1.2.iu kin sinh thi- Kh hu:

Nhit khng kh trung bnh hng nm t 20 - 25 oC , nhit khng kh trung bnhthng lnh nht t 15 - 20 oC.

Lng ma trung bnh hng nm t 2.000 mm - 2.500 mm, nhiu vng c lng mart cao t 3.000 mm - 4.000 mm

Ch s kh hn chung: 3 - 0 - 0 Hng nm khng c thng hn, thng kit, ch c 3thng kh.

m khng kh tng i trung bnh trn 85% Lng bc hi thng thp.

- t: m: nai (gneiss), phin thch mica (micaschiste), phin sa thch (gres schisteux), vi hoa cng (microgranit ), lu vn (rioolit), hoa cng (granit), huyn v (bazan)v.v

t a i ca vnh ai nhit i m vng thp

t vng Feralit hon ton thnh thc, su, dy, khng c tng ong.

t hung (terra rossa) nhit i phong ho trn vi v trn t bi t trong thunglng di chn cc ni vi. Theo Friedland, y l loi t en macgalit.

3.1.3. Cu trc rnga) Cu trc tng th

Nhng h sinh thi rng thuc kiu thm thc vt ny c nhiu tng, cao t 25 - 30 m, tnkn rm bi nhng loi cy g ln l rng thng xanh.

Cu trc tng th c 5 tng :

- Tng vt tn A1: hnh thnh bi nhng loi cy g cao n 40 - 50 m, phn ln thuc hDu (Dipterocarpaceae), h Du tm (Moraceae), hu (Leguminosae) v.v Phn lnl loi cy thng xanh nhng cng c loi cy rng l trong ma kh rt. Tng nythng khng lin tc, tn cy xo rng hnh , hnh tn.


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- Tng u th sinh thi A2: y cn gi l tng lp qun bao gm cy g cao trung bnh t20 - 30 m, thn thng, tn l trn v hp, tng tn lin tc, phn ln l nhng loi cythng xanh thuc cc h D (Fagaceae), h Re (Lauraceae), h Vang (Caesalpiniaceae),h Trinh n (Mimosaceae),

Hnh s 4. Cy ch ngn nm, Vn quc gia Cc Phng, Ninh Bnh H sinh thi rngkn thng xanh ma m nhit i. (nh: VNTTX - Phm )


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Hnh s 5. Bnh v cy rng nhit i, Vn quc gia Ct Tin, ng Nai

Hnh s 6. Cnh quan sinh thi vn quc gia Phong Nha, Qung Bnh


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Hnh s 7. Cnh quan sinh thi vn quc gia Ct B, Hi Phng

Hnh s 8. Phu din rng kn thng xanh ma m nhit i(Theo Thi Vn Trng)

h Cnh bm (Papilionaceae), h B hn (Sapindaceae), h Xoan (Meliaceae), h Mc lan(Magnoliaceae), h Trm (Burseraceae) v.v...

- Tng di tn A3: cao t 8 - 15 m, mc ri rc di tn rng, tn hnh nn hoc hnh thpngc. T thnh loi cy thuc cc h Ba (Clusiaceae), h Du (Ulmaceae), h Mu ch(Myristicaceae), h Na (Annonaceae), h Mng qun (Flacourtiaceae) v.v... Ngoi ra cnc cy con, cy nhca cc loi cy tng A1 v tng A2 c kh nng chu bng.

- Tng cy bi B: cao t 2 - 8 m. T thnh loi cy thuc cc h C ph (Rubiaceae), hTrc o (Apocynaceae), h Cam qut (Rutaceae), h Na (Annonaceae), h Mua(Melastomaceae), h Nhn sm (Araliaceae), h Thu du (Euphorbiaceae) v.vNgoi racn c nhng " cy g gi " thuc h Da (Palmae), h ph Tre na (Bambusoideae), hS (Scitaminaceae) v.vTrong tng ny cn c nhng loi quyt thn g, chu c bngrp. Tham gia tng ny cn c nhng cy con, cy nhca nhng loi cy g ln tngA1 , A2 , A3.


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- Tng c quyt C: cao khng qu 2 m. T thnh loi cy thuc cc h r (Acanthaceae),h Gai (Urticaceae), h Mn ry (Araceae), h Gng (Zingiberaceae), h Hnh ti(Liliaceae) v nhng loi dng x v.vTham gia tng ny cn c nhng cy ti sinh canhng loi cy g ln tng A1 , A2 , A3.

Ngoi 5 tng trn, cn c nhiu thc vt ngoi tng, chng tham gia vo tt c cc tngtrong h sinh thi rng nh dy leo, thc vt ph sinh, thc vt k sinh. Thc vt ngoi tng a

dng phong ph l mt c im in hnh ca rng ma nhit i.Dy leo c th l thn g hoc thn c thuc cc h u (Leguminosae), h Na

(Annonaceae), h Trc o (Apocynaceae), h Gm (Gnetaceae) v.v... Ngoi ra cn c nhngloi dy leo in hnh ca rng nhit i thuc h C da di hng trm mt thuc cc chiCalamus, Daemonorops c hu ca vng ng Nam .

Thc vt ph sinh (loi thc vt sng nhvo nhng loi cy khc) gm nhng loi cythuc h Phong lan (Orchidaceae), h Mn ry (Araceae), nhng loi quyt thuc cc chiAsplenium, Drynaria, Platycerium, c bit l nhng loi cy sng nhcy k ch nh loi a(Ficus), chn chim (Schefflera) v mt loiFragraea obovata trong h Loganiaceae.

Thc vt k sinh bao gm nhng loi cy thuc chi Loranthus trong h Tm gi

(Loranthaceae), chi Balanophora trong h Cu ch (Balanophoraceae) sng bm trn cnh l v rcy.

b) Cu trc t thnh loi thc vt, cc kiu ph v u hp Cc kiu ph min v u hp:

Kiu ph min thc vt thn thuc vi khu h thc vt Malaixia - Innxia , u hp hDu (Dipterocarpaceae)

Phn b: Kiu ph min ny phn b rt rng. min bc Vit Nam, chng phn bdi cao so vi mt bin t 600 - 700 m, nam Trung B di cao 800 - 900 m v NamB di cao 1.000 m. Ngoi ra, cn c th tm thy kiu ph ny cc thung lng gia cc

ni vi v vng thp ven cc sng ln.Cu trc tthnh loi cy gln: c trng cbn d nhn bit ca kiu ph ny l

u thca cc loi cy h Du (Dipterocarpaceae) cc tng trn, nht l tng vt tn v tngtn rng. Phn ln cc loi cy rng u thng xanh nh Sao en (Hopea odorata), Kin kin(Hopea pierrei), Sng o (Hopea ferrea ), Tu mt qu (Hopea mollissima), Tu l nh (Vaticatonkinensis), Tu mui (Vatica fleuryana), Ch en (Parashorea stallata) v.v... min Nam, cbit l Ty Nguyn, loi cy tiu biu cho h Du l cy Du ri (Dipterocarpus alatus), Dung (Dipterocarpus turberculatus).

Ngoi cy h Du (Dipterocarpaceae), cn c nhng loi cy bn a thng xanh thuccc chi :

- Sindora, Ormosia, Cassia v.v thuc hu (Leguminosae)- Lithocarpus, Castanopsis, Quercus v.vthuc h D (Fagaceae)

- Syzygium, Eugenia thuc h Sim (Myrtaceae)

- Camellia, Terstoemia, Schima thuc h Ch (Theaceae)

- Garcinia, Mesua, Calophyllum thuc h Ba (Clusiaceae )

- Dracotomelum, Bouea v.v... thuc h Xoi (Anacardiaceae)


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- Aglaia, Aphanamixis, Dysoxylon, Chisocheton thuc h Xoan (

Meliaceae)

Tthnh loi cy bi thng bao gm nhng loi cy thuc cc chi :

- Psychotria, Prismatomeris, Pagetta, Ixora, Lasianthus v.v thuc h

C ph (Rubiaceae)

- Ervatamia, Tabermontana, Rauwolfia v.vthuc h Trc o (Apocynaceae)

- Ardisia, Maesa v.v thuc hn nem (Myrsinaceae)

- Polyalthia v.vthuc h Na (Annonaceae)

- Diospyros v.vthuc h Th (Ebenaceae)

Ngoi ra cn c nhiu i din thuc h Da (Palmae),

Tthnh tng c quytc nhiu dng x .

c trng cu trc cbn nht ca kiu h sinh thi rng ny l c t thnh loi cy hngiao phc t p nhiu tng, hnh thnh nn nhiu phc h p trong c cu h p, thm ch c

nhng qun th rng t nhin gn nh thun loi. Di y ch gii thiu nhng u hp thc vtrng ca nhng loi cy c hu c gi tr kinh t.

Cc u hp :

- u hp Sao en (Hopea odorata)

Theo Maurand (1943), rng sao nguyn sinh c L Lt ( Nha Trang ). Thi Vn Trng(1952) cng pht hin rng sao t nhin gn nh thun loi dc Bt gia Hu v Nng, cao so vi mc nc bin khong 500 - 600 m. Trn v 16 o Bc bn cu, cha pht hin thysao mc t nhin. Sao l loi cy a sng, i hi t phi tt, su, m. Sao trng ti ph L c(H Ni) lm cy xanh bng mt, sinh trng thn thng p nhng ra hoa kt qu km. iuny chng t H Ni v min Bc ni chung khng cn l vng phn b t nhin ca loi cySao en. Sao l loi cy rng nhit i c gi tr, g tt dng trong xy dng, ng tu thuyn,cn c nghin cu bo tn, xc tin ti sinh t nhin v gy trng pht trin.

- u hp Kin kin (Hopea pierrei)

Kin kin l loi cy c hu xut hin vng trung gian gia hai khu h thc vt Bc vNam. Schmid pht hin kin kin trong qun th rng thng xanh ma m nhit i vngthng du Nam B v nam Trng Sn. min Bc, Kin kin phn bn Qu Hp, Nghan (Ngh An) v Nh Xun (Thanh Ho). C th xc nh gii hn pha bc ca loi cy kinkin n vtuyn 20o C bc bn cu v di cao 350 m so vi mc nc bin. Viu kint, u hp ny pht trin ch yu trn t vng Feralit v cng c th pht trin trn t do vi phong ho.

Kin kin c th tham gia vo qun th vi t cch l loi cy u th, c khi chim n70% c th tng vt tn. Chiu cao c tht n 23 - 25 m v ng knh trn 40 cm. min Nam, chng mc hn giao vi mt s loi cy h Du (Dipterocarpaceae) v Ngh Anmc hn giao vi cc loi cy Ch ch (Parashorea chinensis), Lim xanh (Erythrophleum fordiiOlive) v.v... Kin kin ti sinh mnh nhng qun th rng c tn che khong 0,6 - 0,7 vii din nhiu kch thc khc nhau. Kin kin l loi cy rng bn a c hu c gi tr gtt, p dng trong xy dng, ng tu thuyn, trang tr ni tht v.v Cn nghin cu bo tn,xc tin ti sinh t nhin loi cy ny t vtuyn 20o trvo.


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- u hp Ch ch( Parashorea chinensis)

Ch ch l loi cy rng c hu vng qu trung gian gia hai khu h thc vt Namv Bc. Tuy nhin, phn b t nhin loi ch ch c thn cc thung lng, lu vc cc sng Lo Cai, Yn Bi, Tuyn Quang, Bc Kn, Thi Nguyn, Lng Sn, Ninh Bnh, Thanh Ho,Ngh An v.vPhn b t nhin theo cao ca loi cy Kin kin ti Ngha n (Ngh An) tn cao 300 m so vi mc nc bin. Cha c ti liu no pht hin ch chkhu h thc vt

Vn Nam - Qung Ty (Trung Quc), v vy c th khng nh y l loi cy c hu ca khuh thc vt Vit Nam.

Ch ch tham gia vo thnh phn ca qun th rng thng xanh, phn b t v 16o -22o B trn cc loi t vng Feralit, yu cu m t ln nn thng xut hin trong ccthung lng gia cc trin ni vi, ven khe sui , sng ngi. Ch ch l loi cy thng xanhnhng trong nhng nm kh rt ko di cng rng l ng lot. Thn thng trn, cao n 40 - 50m chim v tr tng vt tn A1. Ch ch c th mc hn giao vi Lim xanh (Erythrophoeumfordii Olive) v cc loi cy rng khc to thnh mt qun th kn rm c tn che n 0,7 -0,8. Ti sinh cy m ch ch di tn rng c nhiu nhng cy con, cy nhc rt t. iu chng t cy m ch ch c kh nng chu bng, nhng khi ln ln nhu cu nh sng ngy cngnhiu nn khng th tn ti c di tn rng. Ch ch l loi cy c hu c gi tr cao, gcng bn, t b mi mt dng ng thuyn, lm ct bum v cc cng trnh xy dng. Cnnghin cu bo tn, xc tin ti sinh v gy trng pht trin loi cy ny.

- u hp Ch nu (Dipterocarpus tonkinensis)

u hp Ch nu phn bPh Th, Yn Bi, Tuyn Quang, Thi Nguyn, Thanh Hov.vy l vng thp c kh hu m t. Ch nu cao n 35 - 40 m thng chim v tr tngvt tn trong qun th. Cy ra hoa kt qu hng nm, sai qu, ht d ny mm, c kh nng phttn ht ging i xa nhqu c cnh. G Ch nu khng cng nh Ch ch nhng nu bo quntt th c th s dng ng thuyn. Mt sa phng Ph Th trng Ch nu hn giaovi M( Manglietiaconifera) trn t rng cn tt m.

- u hp Du ri (Dipterocarpus alatus)u hp ny phn b ch yu min Nam, t Qung Nam n min ng Nam B, c

bit c nhiu Ty Nguyn. Vc Minh (1963) pht hin u hp Du ri B Trch (QungBnh) Trong kiu thm thc vt rng kn thng xanh, Du ri v Vn vn (Anisoptera costata)thng chim v tr tng A1. Nhng u hp cy h Du (Dipterocarpaceae) sc trnh by mc 8.3.5. H sinh thi rng tha cy h Du (cn gi l rng khp)

- Cc u hp tu (Vatica sp)

u hp Tu mt qu (Hopea mollissima)

u hp ny c nhiu Hng Sn (H Tnh). Tu mt qu chim u th trong qun thrng kn tn vi tn che 0,7 - 0,8, chiu cao t ti 30 - 35 m, mang c trng in hnh ca

cy rng nhit i l c bnh v cao n 5 - 6 m. Tu mt qu mc hn giao vi su(Dracontomelumduperreanum) v mt s loi cy khc thuc cc chi Lindera, Litsea, Phoebe,Cinnamomum chim v tr tng A1 . Tng A2 gm mt s loi cy nh Nang trng (Horsfieldiaamygdalina), Mu ch (Knema conferta),


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Hnh s 9. Phu din rng thng xanh ma m nhit i Hng Lin, Hng Kh, H Tnh(Theo Phng Ngc Lan v Bi nh Toi)

Trm (Syzygium sp.). Tng A3 c Ba (Garcinia oblongifolia), Ngt (Gironnierasubaequalis ), Trm trng (Canarium album), re (Cinnamomum sp.). Tng cy bi cao t 5 - 7 m,tha tht gm loi cy Nh ni (Diospyrosfilipendula), Chn (Microdesmis caeserfolia) v.v,

mt s loi cy trong h Na (Annonaceae), mt s loi trong chi Litsea thuc h Re (Lauraceae).Tng c quyt rm rp gm cc loi dng x thuc cc chi Asplenium, Diplazium, Tectariav.vThc vt ph sinh c nhiu, c bit c loi a (Ficus) mc trn cc cy tu, c, su. GTu mt qu cng bn c s dng trong xy dng v ng thuyn. Cn xc tin ti sinh tnhin, c th trng trn t rng mi khai thc nhng phi trng hn loi vi nhng loi cy mcch khc hoc cy ph tr.

u hp Tu mui (Vatica fleuryana)

u hp ny phn b cao t 300 - 800 m nhng phn b tp trung cao t 600 -700 m (theo Vin iu tra Quy hoch rng) trn t Feralit vng c tng t kh dy. u hpny c nhiu Hng Sn (H Tnh). T thnh loi cy ca u hp ny phc tp nhng Tu

mui vn chim u th, tn che ca rng 0,7 - 0,8, tng tn lin tc. Ngoi tu mui cn cTu mt qu, Lim xanh (Erythrophloeum fordii Olive), mt s loi cy trong h D (Fagaceae),h Re (Lauraceae) v.v tng di tn, Tu mui khng chim u th r rt. Tng cy bi thmti tha tht, Ti sinh tt nhng phn ln l cy m, chng t tn che cao ch thch hp chonhng loi cy m c kh nng chu bng. Cy con v cy nhti sinh thiu nh sng khng tnti c. G Tu mui khng bn, d b mc nn cn c bo qun trc khi s dng.

u hp Tu mt l nh + Tu mui (Vatica tonkinensis + Vatica fleuryana)

Vc Minh gp u hp ny ti K Ln (Tuyn Quang) cao 480 m so vi mcnc bin. Tu mt l nh v tu mui chim u th trong t thnh tng cy g , cy cao n 30


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m, hn giao vi Trm trng (Canarium album), Mu ch ( Knema conferta), Lng mang(Pterospermumlancaefolium) v.v

Tng cy bi thp gm c cc loi Gordonia sp, Ardisia sp, Alchornea rugosa, Psychotriamontana, Chloranthus sp, Antidesma, Strobilanthes v.v

Tng c quyt gm c cc loiPanicum sp, Tectaria, Abacopteris, Scleria v.v

Vc Minh cn gp u hp ny ti V L ( Thi Nguyn ). y, Tu mt l nh mc hngiao vi Sn mt (Madhuca pasquieri), Trm en (Canarium nigrum), Rng rng mt (Ormosiabalansae), re (Cinnamomun sp.), kho (Phoebe sp.), Ngt (Gironniera subacqualis), Lng bng(Dillennia heterosealpa), Ba (Garcinia oblongifolia) v.v

Tng cy bi gm c cc loi Ardisia conjugate, Psychotria montana, Phyllostachys sp,Melastoma sp, Annona sp v.v

Tng c quyt c Tectaria quintaphylla, Selaginella rependa, Diplajium sp , Scleriaherbacarpa v.v

C hai u h p ny u c Tu mt l nh ti sinh, cy cao n 1 - 2m, cy m nhiunhng cy con v cy nht . Loi cy ny cng ch chu bng trong giai on cn nh.

G Tu mt l nh cng bn c s dng trong cc cng trnh xy dng v ng thuyn.

u hp Vn vn (Anisoptera costata)

u hp ny xut hin trong kiu rng l rng thng xanh ma m nhit i vng thp.Vit Nam c hai loi vn vn ( Anisoptera costata v Anisoptera glabra) u thuc h Du.Chng mc hn giao vi Du ri (Dipterocarpus alatus).

Trong kiu rng kn l rng thng xanh ma m nhit i cn c nhiu u hp cy hDu thuc kiu ph min thc vt Malaixia - Indonesia nhng cha pht hin c ht, cnnghin cu b sung.

Kiu ph min thc vt thn thuc khu h thc vt Bc Vit Nam - Nam Trung Hoa.

Kiu ph min ny thng vng thp, min Bc di cao 700 m so vi mc ncbin v trn ng ng nhit thng lnh nht 20o C; min Nam vng thp m, di cao1.000 m so vi mc nc bin thuc dy Trng Sn.

Kiu ny bao gm nhiu u hp h nh :

- u hp h Re (Lauraceae)

-u hp h D (Fagaceae)

- u hp h Xoan (Meliaceae)

- u hp h Du tm (Moraceae)- u hp h Mc lan (Magnoliaceae)

- u hp hu (Leguminosae)

- u hp h Xoi (Anacardiaceae)

- u hp h Trm (Burseraceae)

- u hp h B hn (Sapindaceae)


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- u hp h Hng xim (Sapotaceae)

- v.v

T thnh loi cy phn ln l thng xanh c xen ln mt s loi cy rng l, khng ctng vt tn r rt, cy c bnh v ln. Tng cy bi th p nhiu cy thuc h C da(Palmaceae), h ph Tre na (Bambusoidae). Dy leo thn g v thc vt ph sinh (phong lan),mn ry v.vc nhiu.

Trn Ng Phng v Vc Minh (1970) cng pht hin hai loi hnh thc vt kh hu ai thp di 300 m so vi mc nc bin l u hp Lim xanh (Erythrophoeum fordii Olive) to Ngang tr ra v u hp g + hunh(Sindora cochinchinensis + Tarrietia javanica) toNgang trvo. vnh ai cao 300 - 700 m c u hp Sn + Tu (Madhuca pasquieri + Hopeamollissima).

Vnh ai nhit i vng ni c u hp D (Castanopsis).Nhng u hp h trong kiuph min ny cn c nhiu nhng cha pht hin ht.

Kiu ph th nhng:

y l kiu thm thc vt rng ph hnh thnh do iu kin th nhng quyt nh, mc d

c chung iu kin kh hu nh cc kiu thm thc vt khc.Kiu ph thnhng kit nc trn ni vi

H sinh thi rng trn ni vi l mt th din hnh (xem mc 8.3.3).

Kiu ph thnhng ng nc mn

H sinh thi rng ngp mn l mt th din hnh (xem mc 8.3.6)

3.1.4. Ti sinh v din thrngTc ng ca con ngi n h sinh thi rng rt a dng v phc tp v nhng hnh

thc, mc khc nhau. Chnh tc ng ny l nguyn nhn dn n qu trnh din ththsinhv to nn nhng kiu ph thsinh nhn tc.

Trong qu trnh din th th sinh hnh thnh nn nhiu u hp khc nhau tu theo hnhthc, mc tc ng ca con ngi tiu cc hay tch cc.

a) Tc ng ph hoi ca con ngi:Sau nng ry:

- u hp M+ Rng rng mt ( Manglietia conifera + Ormosis balansae)

u hp ny phn b nhiu Tuyn Quang, Yn Bi, H Giang v.vVng ny c chkh hu ma nhiu v m, t cn tnh cht t rng. Bc Quang (H Giang) tng xut hinti sinh rng rng thnh nhng qun th rng phc hi sau nng ry gn nh thun loi. MvRng rng mt l hai loi cy rng a sng nhng c i sng di, t kch thc ln. y l loicy tin phong nh c. Nu c bo v nghim ngt c th phc hi li rng c gi tr kinh t.

- u hp hu ay + hu tru + hu nu + ba bt + ba soi + hu en

u h p ny xut hin nhiu vng kh hu m nh Ph Th, Tuyn Quang, Yn Biv.vTi sinh nhiu loi cy a sng hnh thnh nn nhng u hp gn nh thun loi nh hu ay(Trema angustifolia), Ba bt (Mallotus apelta), Hu en (Commersonia echinata), hu nu(Mallotuscochinchinensis ), hn giao vi Ba soi (Macaranga denticulata). Ngoi ra, cn gp tisinh ca cc loi cy khc nh B (Styrax tonkinensis), Mng tang ( Litsea citrata), Tru


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( Aleurites montana), Na l to (Schizostachyumfunghomii), M (Manglietia conifera), Limxanh (Erythropheoum fordii Olive) v.v Nhng loi cy hu l loi cy a sng, mc nhanh, isng ngn, ch l cy tin phong tm thi. Tuy nhin, nu c bo v nghim ngt th di tnrng s xut hin ti sinh nhng loi cy chu bng, mc chm hn v c gi tr kinh t.

Mi vng c iu kin sinh thi, khu h thc vt a phng khc nhau nn t thnh qun thphc hi sau nng ry cng khc nhau.

- u hp thn tho

Hnh s 10. t rng lm


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Hnh s 11 . Din th th sinh loi m ca thm thc vt nhit ivng thp tnh Yn Bi ( theo Thi Vn Trng )

Rng kn thng xanhm nhit inguyn sinh

(d , d gai)+(re, m,c l)+( vnganh,rng rng)+(gi np, gi nc,

quych)+ (m, gii)+trm trng+chnu+lim xanh+sn mt+tu l nh

Rng kn cy g lnth sinh thng xanh v

na rng l

lim xanh+trmtrng+rng

rng+m+cho+(d ,d gai)+(re,

kho)+ch nu

b +lim xt+rng rng+trm

+re, kho+d , d gai

Rng kn cy g thpth sinh thng xanh v

na rng l

m + hu +ba soi + cho

b + hu +ba soi + lim xt

Rng tre naxen cy g

na nm + hu +ba soi + giang

na tp + b

Rng tre na na nm + giang na tp + giang

gy

Trng c th sinh c lau + c chtc ch v+c

tranh

t m mt,cnmn v ti xp

t xi mn,nng cn, kh

nng, cng cht


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Hnh s 12. Din th th sinh loi kh ca thm thc vt rng vng Bin ng, tnh Bc Giang v Hu Lng, tnh Lng Sn.

( theo Thi Vn Trng )

QUN H X HP

lim xanh+ sau sau + re + kho + d gai + d Rng kn na rng l

sau sau+ thnh ngnhRng kn rng l

thnh ngnh+ c lo + thu tu + c tranhRng tha rng l

c lo + c tranh + c ch v+ thu tuTrng cy bi

Trng c th sinh c tranh c ch v

Rng kn thng xanhlim xanh

+ sn mt + tu l nh + d gai + d + re + kho


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u h p thn tho c nhiu nh chui rng, lau, cht, ch v v.vt u h p chuirng cn m nhng u hp lau, cht, ch v th t thoi ho sang trng thi xu hn.

+ Sau khai thc rng :

- u hp Lim xanh + Trm trng (Erythrophoeum fordii+ Canarium album)

u h p ny xut hin sau khai thc chn nhng vng c lim xanh phn b. Chnh

nhng cy m ca th h rng c l ngun ht ging cho ti sinh rng sau khai thc. Lim xanh lloi cy a sng nhng chu bng trong giai on cn nh. Sau khi khai thc, tn rng b ph vto iu kin cho ti sinh lim xanh v cc loi cy khc sinh trng pht trin tham gia vo tthnh ca rng.

- u hp Na l to (Schizostachyum funghomii)

u hp ny phn bdc theo cc con sng ln nh sng Hng, sng M, sng Chu,sng Chy, sng L v.vu hp ny c cc tnh Lo Cai, Yn Bi, Tuyn Quang, Ph Th, BcKn, Thi Nguyn, Cao Bng, Lng Sn, Thanh Ho, Ngh An, H Tnh v.vTng cy g cnst li sau khai thc l Lim xanh (Erythrophoeum fordii), Trm trng (Canariumalbum), Ngt(Gironniera subaequalis), Ch nu (Dipterocarpustonkinensis) v.vDi tng ny l na pht

trin dy c to thnh tng tn na lin tc c tn che cao. y l nguyn nhn lm cho tisinh ca nhng loi cy g rt kh khn. Qun th na n nh trong thi gian di v kh c loicy no cnh tranh c vi na. Ch trong trng hp na b khuy th qun th rng na mic thay th bng mt qun th khc.

- u hp Giang (Maclurochloa sp.)

u hp ny phn b nhiu vng m. Thn khng mc thng ng m chng cho lnnhau lm cho rng kn rm rp . Ti sinh ca cc loi cy g rt kh khn. Do vy, qun th rnggiang tn ti trong mt thi gian di. t di rng giang khng tt lm nn nhn dn c kinhnghim l khng t rng giang lm nng.

Nhng u hp xut hin sau khai thc ph thuc vo rt nhiu yu t. l t thnh ca

rng trc khai thc, t thnh loi cy khai thc, cng v lun k khai thc, kthut khai thcv vn xut v.v Do vy, mi a phng c th xut hin nhiu u hp sau khai thc khcnhau.

b) Tc ng tch cc ca con ngiy l nhng kiu ph nui trng nhn to. Con ngi trng rng mi nh rng thng,

m, bch n, b, lung, phi lao, c v.v(xem chng Trng rng trong Cm nang ngnhlm nghip)


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Hnh s 13. Rng trng bch n (E. urophylla), Tuyn Quang


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Hnh s 14. Voi rng nhit i Ty Nguyn, Vit nam

Hnh s 15. H, ng vt qu him, trong rng nhit i Vit Nam

3.1.5. ngha kinh t, phng h v khoa hcH sinh thi rng ny phn b rng trn cc tnh trung du v min ni Vit Nam. Tr

lng grng nguyn sinh c tht n 400 - 500 m3/ ha, trong c nhiu loi g qu nhiti v l loi bn a c hu ca Vit Nam c gi tr s dng cao nhinh, lim, sn, tu v.vv

c bit l c nhiu loi lm sn ngoi g c gi tr nh dc liu qu, nhiu loi cy cho nha vtinh du v.vy l i tng rng khai thc trong nhiu nm qua v cung cp mt khilng ln g xy dng, nguyn liu cng nghip ch bin lm sn v.v cho nn kinh t qucdn. Tuy nhin, do khai thc chy theo k hoch trong thi kinh t bao cp, khai thc khng ngkthut, khng bo m ti sinh rng nn din tch v tr lng rng b suy gim. T l rngth sinh ngho kit tng ln. Trong nhng nm gn y, ngnh lm nghip c ch trng hnch lng khai thc g rng t nhin, tin ti "ng ca" rng t nhin. Ngoi ra, nhiu khu rngnguyn thu nhit i nh Cc Phng (Ninh Bnh), Phong Nha - K Bng (Qung Bnh), BchM (Tha Thin - Hu), Ct Tin (ng Nai) v.v , ang v s mang li ngun thu nhp lnt du lch sinh thi.

H sinh thi rng ny phn bhu ht cc vng u ngun ca cc con sng ln Vit

Nam. y l kiu h sinh thi rng nhit i in hnh c c trng bi rng l rng thngxanh hn giao phc tp nhiu tng tn. C th coi nhng c trng ny l m hnh chun png ti u cho yu cu phng hu ngun min ni v trung du. Trn thc t, kiu h sinhthi rng ny v ang gi vai tr cc k quan trng cho vic nui dng ngun nc, bo vt, chng xi mn, hn ch l lt cho c vng ng bng, th v ven bin Vit Nam.

H sinh thi rng nhit i ny c tnh a dng sinh hc cao c va dng ngun gen, adng loi v a dng h sinh thi. Trong h sinh thi ny c nhiu loi thc vt ng vt rng quhim, c loi ang be do dit chng cn c bo tn nghim ngt v pht trin. y l i


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tng nghin cu khoa hc ca cc vn quc gia, khu bo tn thin nhin v nhiu cquannghin cu trong v ngoi ngnh lm nghip. Di tm mn xanh ca nhng h sinh thi rngnhit i ny vn cn cha ng bit bao iu b n m cc nh lm sinh hc Vit Nam cha phthin c.

3.2. H sinh thi rng kn na rng l m nhit i

3.2.1. Phn bH sinh thi rng ny phn bQung Ninh, Bc Giang, Bc Kn, Tuyn Quang, Ph

Th, Yn Bi, Sn La, Lai Chu, Thanh Ho, Ngh An, Ty Nguyn, min ng Nam B v.v

Phn b theo cao so vi mc nc bin :

min Bc : di 700 m

min Nam : di 1.000 m

3.2.2.iu kin sinh thi- Kh hu:

Nhit khng kh trung bnh hng nm 20o - 25o C

Nhit khng kh trung bnh thng lnh nht 15o - 20oC

Lng ma trung bnh hng nm 1.200 - 2.500 m

Ch s kh hn (1-3) - (0-1) - (0)

Ma hn ko di t 1 - 3 thng vi lng ma di 50 mm v mt thng c lng madi 25 mm.

m trung bnh thp nht trn 85%

- t: m: phin thch, sa thch, sa dip thch, badan, ph sa c, k ct vi hung ,t nu en v.v

t vng Feralit, tng t dy

3.2.3. Cu trc rnga) Tng th

Cu trc tng th gm 3 tng cy g (A1 , A2 , A3). in hnh l hai loi cy rng l :Sng l (Lagerstroemia tomentosa ) v Sau sau (Liquidambar formosana). Ngoi ra cn c ccloi cy thuc h Dipterocarpaceae, Meliaceae, Leguminosae, Datiscaceae, Moraceae,

Anacardiaceae, Combretaceae, Lauraceae, Burseraceae, Sapindaceae v.v Chiu cao qun tht n 40 m. Nhiu loi cy c bnh v.

Tng di tn v tng cy bi tha.

Tng thm ti rm rp c cc loi quyt (Pteridophyta) v cy h Da (Palmae)

b) Cu trc t thnh loi thc vt, cc kiu ph v u hpCc kiu ph min


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Kiu ph min thc vt thn thuc vi khu h Malaixia - Innxia v khu hn -Myanma .

Kiu ph ny pht hin Mng Xn, Con Cung (Ngh An), in hnh l cy Sng l( Lagerstroemia tomentosa) mc hn giao vi Lim xanh ( Erythrophoeum fordii), Lim xt(Peltophorum tonkinensis), Sn mt (Madhuca pasquieri)

c trng cbn ca h sinh thi ny l s c th rng l phi c t 25 - 75% so vi tngs c th trong qun th. Ngoi hai loi cy rng l in hnh l Sng l (Lagerstroemiatomentosa) ty bc Ngh An v Sau sau (Liquidamba formosana) Bin ng, Bc Giang.Ngoi ra cn c nhiu

Hnh s 16. H sinh thi rng hn giao nhit i min ni nh: VNTTX - Tun Hi

loi cy rng l khc nh cc loi d (Quercus acutissima, Quercus serrata,Quercus griffithii),B (Styrax tonkinensis), Xoan ta (Melia azedarach), Lim xt (Peltophorum tonkinensis ) Cqun th t thnh loi cy rng l gn nh thun loi nh Sng l (Lagerstroemia tomentosa) Con Cung (Ngh An), Sau sau (Liquidamba formosana ) Hu Lng (Lng Sn) v Bin ng(H Bc) Khu h thc vt Vit Nam c nhiu loi cy rng l thuc cc h Dipterocarpaceae,Leguminosae, Combretaceae, Datiscaceae, Sterculiaceae, Anacardiaceae, Meliaceae,Sapindaceae, Bignoniaceae, Ulmaceae, Moraceae, Verbenaceae iu d nhn bit l mt s loicy rng l tham gia vo qu trnh din th phc hi rng sau nng ry nh B (Stryraxtonkinensis) Ph Th, Tuyn Quang v Sau sau (Liquidamba formosana) Hu Lng (LngSn) v Bin ng (H Bc)

Trong h sinh thi rng ny, nhng loi cy rng l cn mc hn giao vi cc loi cythng xanh khc thuc cc h Lauraceae, Burseraceae, Meliaceae, Moraceae, Sapindaceae

Kiu ph min thc vt thn thuc vi khu h bn a Bc Vit Nam - Nam Trung Hoa vkhu h di cn - Myanma

Kiu ph min ny c cc loi cy rng l thuc cc h Meliaceae, Sapindaceae,Leguminosae, Anacardiaceae, Burseraceae, Verbenaceae Nhng loi ny rng l dn dn v kodi trong sut ma kh hn. iu ng ch l nguyn nhn rng l ca mt s loi cy trong hsinh thi rng ny khng ch l do kh hu. Khi rng b khai thc nhiu ln hoc rng phc hi


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trn t ang thoi ho c tng ong ngn cch vi mc nc ngm th hn t lm cho mts loi cy c phn ng rng l trong ma kh hn.

Cc kiu ph th nhng

Kiu ph thnhng kit nc trn ni vi

H sinh thi rng trn ni vi l mt th din hnh (xem mc 8.3.3).

Kiu ph thnhng ng nc mn

H sinh thi rng ngp mn l mt th din hnh (xem mc 8.3.6)

3.2.4. Ti sinh v din thrngDin th th sinh ca h sinh thi ny hnh thnh di tc ng ca con ngi nh phc

hi rng nng ry, sau khai thc v trng li rng mi. Cc u hp trnh by di y l kiuph th sinh nhn tc.

- Tc ng ph hoi ca con ngi:Sau nng ry:

- u hp M+ B+ Xoan ta

u hp ny hnh thnh sau nng ry. Rng phc hi ban u l ti sinh ca loi cytin phong a sng, in hnh nht l loi cy b rng l. C ni hnh thnh nn rng b (Styrax tonkinensis ) t nhin gn nh thun loi nhPh Th, Tuyn Quang, Yn Bi Cc dntc min ni tnh Ho Bnh c kinh nghim gieo ht Xoan ta (Melia azederach) trn nng ry,sau t nng kch thch ht xoan ny mm. Ngoi ra cn c M(Manglietia glauca) cngtham gia vo t thnh rng phc hi sau nng ry v l loi cy tin phong nh v, c kh nngtn ti lu di trong i sng ca qun th.

- u hp na (Shizostachyum funghomii )

u hp ny hnh thnh trn nng ry lu nm, t b thoi ho. Tu theo mc tthoi ho m qun th na phc hi c ng knh cy khc nhau. t cng xu th ng knhna cng nh v tr thnh na tp. Trong qu trnh phc hi rng c th c mt s loi cy tisinh chu hn hn xut hin nh giang (Maclurochloa), st (Arundinaria sp.), trc (Phyllostachyssp.), vu (Acidosasa sp.) Do c th ti sinh thn ngm nn qun th na n nh trong mt thigian tng i di. Khi no na b khuy th s xut hin din th mi tu theo iu kin c thca tng a phng.

- u hp Hu ay + B(Trema angustifolia + Styrax tonkinensis)

u hp ny hnh thnh sau nng ry, phn bvng kh hu m, c ni phc hi thnhrng B (Styrax tonkinensis) gn nh thun loi.Ban u nhng loi cy tin phong a sngnh Hu ay (Trema angustifolia), Ba bt (Mallotus apelta), Hu nu (Mallotus cochinchinensis)xut hin cng vi loi cy rng l in hnh l loi b. B l loi cy a sng nhng c isng di hn cc loi hu, nhiu a phng hnh thnh nn nhng qun th rng b phchi gn nh thun loi u tui. Qun th rng tin phong ny ch c tnh cht tm thi v cutrc rng thun loi, u tui, mt tng, rng l, tn tha khng thch hp vi iu kin nhit ima nhiu, t dc. Lng t xi mn trong qun th ny cao nn khng thn nh lu di.

Xu hng din th ca qun th s din ra theo hai chiu hng sau y:

Nu bo v rng tt th di tn rng s xut hin ti sinh ca nhng loi cy chu bngthuc cc h Caesalpinaceae, Lauraceae, Fagaceae, Meliaceae v.vTh h cy ti sinh ny s


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thay th rng b v c kh nng hi nguyn li trng thi rng ban u t thnh bi nhng loicy c gi tr kinh t v phng h. y l qu trnh din th tin ho, cu trc rng ngy cngphc tp c v t thnh loi cy v tng th.

Nu rng phc hi khng c bo v th s tip tc qu trnh din th thoi ho, ccloi tre na xm nhp vo thnh phn qun th, chim u th hoc gn nh thun loi n nhhoc din th thnh trng cy bi, trng c th sinh nh cht (Thysanolaena maxima), ch v

(Miscanthus sinensis)Nhng u hp thuc loi ny cn c coi l i tng khoanh nui rng, nu khng ti

sinh ca nhng loi cy mc ch th cn trng dm b sung thm nhng loi cy bn a c gitr.

Sau khai thc rng

- u hp Lim xanh + Lim xt (Erythrophoeum fordii +Peltophorum tonkinensis)

u hp ny hnh thnh sau khai thc chn, phn bBin ng, An Chu (Bc Giang ),Nh Xun ( Thanh Ho ), Qu Chu ( Ngh An ) v.v Ngun gc ban u ca u hp ny lrng hn loi l rng c lim xanh tham gia vo t thnh qun th. Ngoi ra cn c cc loi cy

khc nh trm (Canarium copalierum), Rng rng mt (Ormosia balansae), Lim xt( Peltophorum tonkinensis), cc loi d (Lithocarpus sp , Castanopsis sp), cc loi re(Cinnamomum, Phoebe), M ( Lysidice rhodostegia), Ngt (Gironniera subaequalis), Ba(Garcinia bonii) Nu c bo v v nui dng lu di, u hp ny c kh nng phc hi litrng thi rng ban u. Nu tip tc b khai thc, t b thoi ho c kt vn ong s lm tngt l loi cy rng l trong qun th.

- u hp Sau sau + Lim xanh (Liquidamba formosana + Erythrophoeum fordii)

u hp ny c pht hin Hu Lng (Lng Sn), Bin ng, An Chu (Bc Giang)C th coi y l mt trong nhng vng trung tm phn b ca Lim xanh (Erythrophoeum fordiiOlive) Vit Nam. Trong nhng nm 60 ca th k 20, ni y tng c nhng cnh rng Limxanh t nhin gn nh thun loi, ng knh to n 1 - 1,2 m (Phng Ngc Lan, 1962). Rt ticl con ngi xo i nhng "di sn thin nhin" qu bu ca thm thc vt c xa. Ngun gcca u hp ny l rng hn giao l rng thng xanh. Qua khai thc nhiu ln bin thnh trngcy bi, trng c gut. Ti y, bt u xut hin nhng loi cy c kh nng chng la cao nhHoc quang (Wendlandia paniculata), Thu tu ( Aporosa sp), sau l ti sinh Sau sau(Liquidamba formosana) v hnh thnh nn qun th rng sau sau thun loi, mt loi cy rng lin hnh vng ng Bc Vit Nam. Sau sau l loi cy a sng, tn tha, tn che ca rngkhong 0,4 - 0,5 rt thch hp cho ti sinh ca loi lim xanh. Mt th h cy Lim xanh mi chnh thnh di tn rng sau sau v tham gia vo t thnh ca rng sau ny. Ngoi ra, cn c ccloi cy hn giao l rng khc nh


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Hnh s 18. Khai thc ph hoi rng


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Hnh s 19. Din th rng kiu ph kh hu d gai ( Castanopsis sp ) huynThch An, tnh Cao Bng. ( theo Trn Ng Phng )

Kiu ph kh hu d gai

Castanopsis sp

cng l - kho b sau sau mc ning

Kiu ph th

sinh t nhin

vi thuc

trng c cy bi

trng c

Kiu ph th nhngth sinh nhn tc


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Hnh s 20. Din th rng vng Hu Lng sng Thng, tnh Lng Sn (theo Trn Ng Phng )

Kiu ph nguyn sinh hay phc hi

lim xanh lim xanh + d gai

sau sau Kiu ph phc tp

trng cy g

trng cy bi

trng c

kho (Phoebesp.), re (Cinnamomum sp.), d gai (Castanopsis sp.), d (Lithocarpus sp.)

Nhng u hp hnh thnh sau khai thc chn cn phi c "ng ca rng", nui dng rng phc hi li trng thi rng ban u.

b) Tc ng tch cc ca con ngi

Con ngi tc ng n kiu h sinh thi rng ny thng qua trng rng mi nh m, b, bch n, thng v.v Ngoi ra cn tin hnh tra dm lm giu rng bng nhng loi cy bna c gi tr kinh t ( xem mc 14. Trng rng. Cm nang lm nghip )

3.2.5. ngha kinh t, phng h v khoa hcH sinh thi rng ny phn b tng i rng trn lnh th Vit Nam v nm trong vnh

ai ni thp thuc i tng tc ng ca ngnh lm nghip. Tr lng rng nguyn sinh c tht n 300 - 400 m3 / ha. T thnh rng c nhiu loi cy rng nhit i c gi tr trong cnhiu loi cy bn a c hu ca Vit Nam, c nhiu loi thc vt, ng vt rng qu him vlm sn nhit i ngoi g ln nh dc liu qu, nhiu loi cy cho tinh du, nha, cht bo, tananh v.vy cng l i tng rng khai thc g xy dng v cung cp nguyn liu cho cng


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nghip ch bin lm sn, c bit l nguyn liu cho cng nghip giy si. Tuy nhin, tri quakhai thc nhiu ln, phn ln rng hin cn l rng th sinh ngho nn cn phi c xc tin tisinh, nui dng phc hi rng.

H sinh thi rng ny phn b ch yu min ni v trung du. S tn ti ca h sinh thirng ny gi vai tr cc k quan trng trong vic phng hu ngun, nui dng ngun nc,bo vt, chng xi mn, hn ch l lt cho c vng ng bng, th v vng ven bin.

H sinh thi rng ny cng c tnh a dng sinh hc cao. C nhiu thc vt v ng vtrng qu him c nguy c tuyt chng. Nhiu vn khoa hc nh quy lut ti sinh, din thrng, quy lut sinh trng ca cy rng v rng nhit i v.vang chi cc nh khoa hcnghin cu.

3.3. H sinh thi rng l rng thng xanh trn ni vi3.3.1. Phn b

Din tch rng ni (ch yu l ni vi) Vit Nam c 1.152.200 ha, trong dintch rng che ph 396.200 ha (34,45%),(theo Vin iu tra Quy hoch rng, 1999). Ni viphn b trong 24 tnh v thnh ph nhng ch yu tp trung cc tnh pha Bc v Bc TrungB. Cc tnh c ni vi l: in Bin, Lai Chu, Sn La, Ha Bnh, H Giang, Cao Bng,Lng Sn, Qung Ninh, Hi Phng, Ninh Bnh, Thanh Ha, Thi Nguyn, Ngh An, H Tnh,Qung Bnh.

Nguyn Huy Phn v cng s (1999) phn vng ni vi thnh 5 vng nh sau :

- Vng Cao Bng - Lng Sn

- Vng Tuyn Quang - H Giang

- Vng Ty Bc - Ty Ho Bnh - Thanh Ho

- Vng Trng Sn Bc

- Vng qun oPhn b theo v: t H Tin n Cao Bng (23o B), ch yu t Qung Bnh (17o B) tr

ra.

Phn b theo ai cao t vi chc mt ln n 1.200 m so vi mc nc bin.

3.3.2.iu kin sinh thiKh hu: ngoi ch kh hu chung ca khu vc, do a hnh vng ni vi phc tp

nn c nhng c im khc bit v to nn nhng tiu vng vi kh hu. y l mt qui lut phia i, c trng cho h sinh thi nhy cm trn ni vi Vit Nam.

Nhit khng kh trung bnh nm khong 20o

C. V tng th, nhit trung bnh thngcao nht ca vng ni vi Vit Nam l thng 6 v thng 7, trong khi thng lnh nht lthng 12 v thng 1.

Ch ma v m: theo ai cao th vng ni vi ca Vit Nam c nhng chma khc nhau, , ai th p c ch ma m vi lng ma trung bnh nm t 1200 -2500mm, m khng kh trung bnh 85%. Hin nay cha c s liu kh hu vnh ai ni cao.

Thnhng: ai thp, khu vc ni hnh thnh trn nn m l vi m thnhphn cgii nng l t hung (terra rossa) nhit i. a cht ai cao ca khu vc ni vi


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3.3.3. Cu trc tthnh thc vtTng qut vkhu h thc vt rng trn ni vi Vit Nam:

H thc vt vng ni vi mang tnh cht pha trn ca nhiu lung thc vt nhng ctrng cbn l lung thc vt bn a Bc Vit Nam - Nam Trung Hoa, ng thi cng chunhiu nh hng ca cc lung thc vt khc. Thm thc vt trn ni vi Vit Nam phn b

khng lin tc tp trung vnh ai 300 - 1200m so vi mt nc bin.H thng thm thc vt ni vi phn b theo cao nh sau:

a) ai thp di 700m:Thm thc vt trn ni vi:

Thm thc vt t b tc ng:

Rng kn thng xanh chn ni vi

Rng kn thng xanh sn ni vi

Rng kn thng xanh nh ni vi

Thm thc vt b tc ng:

Rng th sinh thng xanh ni vi

Trng bi v trng c thng xanh ni vi

Thm thc vt trn t phi vi: xen gia cc ni vi:

Rng thng xanh trn t phi vi

Trng cy bi v trng c thung lng ni bn ngp nc v ngp nc

b) ai cao trn 700m:Thm thc vt trn t vi:

Thm thc vt t b tc ng:

Rng cy l rng thng xanh thung lng v chn ni vi

Rng cy l rng thng xanh sn ni vi

Rng hn giao cy l rng l kim ni vi

Rng ln cy l rng nh ni vi

Thm b tc ng (thm thc vt nhn tc):

Rng th sinh ni vi

Trng cy bi trn ni viThm thc vt quanh h Caxt:

Thm thc vt nhn tc

A. Rng ni vi ai thp di 700 m

Phn ln din tch rng ni vi ca khu vc min Trung ai cao di 700 m, trphn pha ty Ngh An gip bin gii Vit Lo. min Bc, rng ni vi thuc ai thp, cvng phn b rng khu vc ng Bc v phn gip ranh gia Ty Bc v ng bng Bc B,


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cc o vi ca vnh Bc B. min Nam (H Tin), ni vi ch gii hn mt vi khini l t, tha tht, mc ln nh nhng hn o, v th trong phn ny ch tp trung m t thmthc vt ni vi min Bc l chnh.

a) H sinh thi rng kn thng xanh chn ni vi:Cu trc rng phc tp, c 5 tng:- Tng vt tn (A1): Cy cao trn 40 m thuc cc h: Leguminosae hay Combretaceae,

Dipterocarpaceae v cc loi ph bin, c trng cho tng ny nh: su (Dracontomelumduperreanum), thung (Tetrameles nudiflora), sng (Pometiapinnata), ch nhai ( Anogeissusacuminata).

- Tng u th sinh thi (A2): gm nhng cy g cao t 20 n 30m, thn thng, tn trngiao nhau lm nn tn rng lin tc. Cc h c nhiu loi

Hnh s 21. Rng thng xanh sn v nh ni vi ai thp,

Hu Lin, Lng Sn.

nh : Nguyn Ngha Thn

cy trong tng ny l: Fagaceae, Lauceae, Caesalpiniaceae, Mimosaceae, Fabaceae, Sapindaceae,Magnoliaceae, Meliaceae v cc loiHopea siamensis, Knema sp,Hopea sp.

- Tng di tn (A3): gm nhng cy cao di 15 m, mc ri rc thuc cc h:Clusiaceae, Ulmaceae, Annonaceae cng viHydnocarpus sp., Sterculia sp., Pterospermum sp.,Baccaurea ramiflora v cc loi c trng c th tm thy nh rui r (Streblus ilicifolius), myto (Streblus macrophyllus) v.v


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- Tng bi (B): gm nhng cy bi, g nh cao di 8 m thuc cc h : Apocynaceae,Rubiaceae, Melastomataceae, Araliaceae, Euphorbiaceae, Acanthaceae v.v

- Tng thm ti (C): gm cc cy thn tho th p (di 2 m) thuc cc h: Araceae,Acanthaceae, Urticaceae, Zingiberaceae, Begoniaceae, Convallariaceae v.v

- Thc vt ngoi tng gm dy leo thuc cc h: Vitaceae, Fabaceae, Connaraceae vcc cy b sinh, k sinh thuc Orchidaceae, Pteridaceae, Araceae, Loranthaceae

y l kiu thm thc vt nguyn sinh m in hnh l rng thung lng ni vi CcPhng ( Ninh Bnh ). Mt su hp c cc loi cy i din nh sau:

-Annamocarya chinensis,Dracontmelumduperreanum,Bischofiajavanica, Saracadives,Saraca indica v.v

- Castanopsissymetri, Cryptocaria impressa,Elaeocarpusvigueri,Nephelium chryseum,Streblus macrophyllus v.v...

- Xerospermum dongnaiensis, Heritiera cucphuongenesis, Heritiera macrophylla,Clausenaexcavata, Streblus macrophyllus, Micromelum falcatum v.v

C nhiu loi cy trong cc u hp ca kiu rng ny c gi tr kinh t cao nh: ch ch(Parashorea sinensis), ch xanh (Terminalia myriocarpa), nghin (Burretiodendron tonkinensis),trai (Garcinia fagraeoides), inh (Markhamia stipularis), inh thi (Fernandoa spp), vng king(Nauclea purpurea) v.v

b) Rng thng xanh sn ni vi:Cu trc rng vi sn ni khc hn vi nh ni v thnh phn loi cy v ngoi

mo. Rng thng c 3 tng: khng c tng A1, 2 tng cy g l A2 , A3 v 1 tng thm ti.

Tng A2 : thnh phn loi cy n iu gm c: rui r (Streblusilicifolius), my to(Streblus macrophyllus), qut hng b (Clausena lansium), lng tong (Walsura sp.), Arytera sp,su (Celtis sp.), trai (Garcinia fagraeoides),Phoebe sp, lt (Chukrasia tabularis), to vng

Drypetes perreticulata), an phong (Alphonsea sp.), mi liu (Miliuisa balansae), cmru (Glycosmis sp.- ), th (Diospyros sp.), bng bng (Arenga pinnata), mu ch (Knema sp.),cch hoa (Cleistanthus sumatranus), nhc (Polyalthia sp.), bnh linh (Vitex sp.), gi (Aglaiagigantea), du da xoan (Spondias lakonensis) v.v

- Tng A3: gm cc loi cy g nh chu bng v cy g ti sinh ca tng trn nh cmngui (Ardisia spp), mn my (Suregadaglomerulata), gng (Randia sp.), Sapindus sp, lu(Psychotria spp), x hng (Lasianthus spp) v.v

- Tng C: gm c cc loi cy quyn b (Selaginellaspp), sa nhn (Amomum sp), cc loidng x Tectaria sp , Pteris spp , Colysis spp , thu hi ng (Begonia spp ), bng nc(Impatiens spp), cao cng (Ophiopogon spp), na (Arisaema sp), Amorphophalus sp, chooc

vi (Arisaema sp), han (Laportea spp) v.v- Dy leo v b sinh: c cc loi dy leo thuc h Bu b (Cucurbitaceae), Dy kh rng

(Connaraceae) v cc loi xoi la ( Pergia sarmentosa), qua lu (Trichosanthes sp ) v cc loib sinh thuc h Phong lan (Orchidaceae), tm gi (Loranthus spp), dng x (Asplenium nidus,Psendodrynaria oronans ) v.v...

c) Rng kn thng xanh nh ni vi:Cu trc rng n gin thng ch 1 n 2 tng cy g. Tng trn gm nhng cy cao t

8 - 15m nhSchefflera spp., Memecylon sp., Sinosideroxylon sp.,Boniodendron sp.,Pistasia sp.,


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cnh kin (Mallotusphilippensis) v.vThc vt tng thp l nhng loi cy bi nhMelastomaspp., Syzygium spp v.v v i khi c s xut hin ca tre na (Sasa japonica) lm thnh rnghn giao tre na trn nh ni vi thp.

Thm ti y thng thng vn l cc loi c trng cho ni vi, nh dng x:Dryopteris, Colysis, Tectaria v.v, quyn b (Selaginella spp), ring (Alpinia spp), thu hing (Begonia spp), bng nc (Impatiens spp), thuc bng (Kalanchoe sp.), v.v

Thc vt ngoi tng c cc loi cy thuc h Phong lan (Orchidaceae), tm gi(Loranthus spp), dy leo nhJasminum sp., mnh bt (Coccinia grandis), i hi (Hodgsoniamacrocarpa) v.v

d) Rng thsinh thng xanh ni vi:Rng ny l hu qu thoi ho ca rng giu trc y sau khi b tc ng ca con ngi

nh khai thc nht l khai thc g nghin lm tht, khai thc v.v tn che ca rng thp.Cu trc tng th ca rng nh sau:

- Tng A1: chim u th l cc loi nghin (Burretiodendron tonkinensis) , su (Celtistimorensis), to vng (Drypetes perreticulata) c chiu cao ti 30m, m rng tai (Macaranga

auricalata ), cui l to (Heritiera macrophylla), inh vng (Fernandoa bracteata). nhng ni mnh khe sui th xut hin loi phay (Duabanga grandiflora) vi thn cao ln.

- Tng A2: y l tng cy g cao 15 - 20 m, gm cc loi tng A1 v my to, rui r,v dt (Hymenodictyon excelsum), tu l nh (Vatica diospyroides), thnh ngnh (Cratoxylumformosum), b (Styraxtonkinensis) v.v

- Tng A3: Tng ny c cc loi cy u th nh: rui r, my to, nhc (Polyalthia sp),Diospyros spp, mi liu (Miliusa sp), an phong(Alphonea sp), bng bc (Mallotus sp ), m rngtai (Macaranga auricalata), chiu cao tng ny ch t 6 - 15 m. Tng di tn tha tht, gm ccloi cy g nh v cy ti sinh ca cc loi cy nh trn tr (Eurya dictichophylla), cnh kin(Mallotus philippensis), ba chc (Euodia lepta), dung (Symplocos sp), sung (Ficus tinctoria), re(Cinnamomum sp),Pterospermum spv.v

- Tng cy bi, thm ti v dy leo c cc loi cy u th nh: lu (Psychotria spp), xhng (Lasianthus sp.), dang dnh (Gardenia sp.), mua (Melastoma spp), me (Phyllanthus sp),c lo (Chromolaena odorata), mc mo (Caesalpinia cucullata ), mng b (Bauhinia spp ), li( Jasminum nervosum ), gm ni (Gnetum montanum ), dy du giun (Quisqualis indica), dychm sao (Combretum sp.) v.v

Trong kiu ny, s xut hin hay khng xut hin ca cc loi a sng mc nhanh l thhin rng pht trin tt thoi ha sau nng ry hay sau khai thc chn. i din cho kiu thnht l cc loi bp bc, m rng tai, cn i din cho kiu th hai l cc loi rui r, my to.nhng ni m cn xut hin nhng qun th vu (Indosasa amabilis ), mai (Dendrocalamusgiganteus)

e) Trng bi v trng c thng xanh trn ni vi :Trn t vi, trng cy bi v trng c cng c hnh thnh do s thoi ha ca rng.

Ti , cht (Thysanolaena maxima ), c lo (Chromolaene odorata ) v bp bc (Mallotuspaniculatus) chim u th hon ton nhng sinh cnh thuc sn ni v st chn ni. Trn nhngbi rng ca cc thung lng, c lo, c tranh cng vi nhng cy bi v cy g nh nh: dng,b (Styrax tonkinensis), thi chanh ( Euodia meliaefolia), mua (Melastoma spp), sm(Memecylon spp), lau (Saccharum spontaneum), gng ( Randia spinosa), b cu v (Breynia


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fruticosa), n but (Bidens pilosa), Solanum torvum v.vcng vi nhiu loi thuc h Thudu (Euphorbiaceae), Dng x.

Dy leo ph bin l cc loi cy thuc h Khoai lang (Convolvulaceae), h Bu b (Cucurbitaceae), h Bng (Combretaceae ), h Nho (Vitaceae) v cc loi bm bm (Entada sp.),xng trn (Platea latifolia ), dy (Iodes cirrhoza),Pegia sarmantosa v.v...

f) Thm thc vt thng xanh trn t phi vi:Thm thc vt nyphn bnhng thung lng xen k gia cc khi ni trn t thot

nc. Tng A1 ch yu l ch xanh, x da voi (Dysoxylum cochinchinensis), thung, ch ch, chnu v.v Tng A2 c cc loi cy u th nh: su, v hng (Cinnamomumbalansae), inh,inh vng, ing thi, trai l, ch nhai v.v Tng A3 c cc loi thuc h Gi (Fagaceae), re(Cinnamomum sp.), th (Diospyros sp.)

nhng ni t thot nc chm hoc bn ngp nc th c cc loi cy a m pht trinrt tt to thnh nhng qun x u th c mt cao, nh qun x go (Nauclea orientalis), qunx dng (Broussonetia papyrifera) v qun x phay (Duabanga grandiflora). y cn xuthin cc loi cy g c bnh v to nh: su, sng, thung v cc loi ch xanh, go (Adina indica),sung, a (Ficus spp), vng anh (Saracadivers), s (Dilleniaindica), go (Bombax ceiba), bn

(Crateva sp), vng (Erythrina indica), r r (Homonoia riparia).g) Trng bi v trng c nhiti trong cc thung lng vi bn ngp nc v ngp nc:

nhng thung lng bn ngp nc, nh sng nhiu th cc loi cy nh hu (Tremaorientalis), c ke (Grewia spp), Colona spp, thao kn (Helicteres), c lo, cht v.v l nhngloi xut hin nhiu nht. Trong iu kin m t, thm thc vt c trng l cc loi: thchxng b (Acorus gramineus), mua (Phyllagathis spp), mn ( Homalomena occulta), ru hm(Tacca chantrieri), r r bi ( Ficus subpyriformis), go nc ( Aidiapilulifera), cm Hi Nam(Elaeocarpus hainanensis), rng t minh (Osmunda vachellii), lau (Saccharum spontaneum),sy(Phragmytes spp), kit (Scleria spp), ci (Cyperus spp). Thc vt thy sinh i din cho nhngvng lun ngp nc l cc loi: rong en (Hydrilla verticillata), rong mi cho (Vallisveria

natans), sung (Nymphaea rubescens), rau mng (Ludwigia spp), bo ong tai chut (Salviniacuculata)

B. Rng ni vi ai cao 700 - 1.000 m

Khu vc ni vi c cao trn 700m, phn b ch yu min Bc, tp trung khuvc ng Bc m i din l Cao Bng, H Giang, Lng Sn v.v Ngoi ra, cn mt snhni vi ri rc Bc Trung B dc theo bin gii Vit - Lo nh: Pu Xai, Lai Leng, P Hot,P Hung, Xun Lin

a) Rng cy l rngthng xanh thung lng v chn ni vi:Nm cc thung hp di chn ni vi, xa dn c nn rng cn tt, mt cy cao,

khp tn t t khong 0,7, cy c kch thc tng i ln, chiu cao trung bnh 15 - 20 m.Rng c cu trc 3 tng cy g:

- Tng A1: cy ln, chiu cao t ti 20 - 25 m. T thnh loi cy bao gm cc loi nhgi (Aglaia sp),phay,inh, sng, nghin, trai, to vng, ch nu (Dipterocarpus retusus), ch ch(Shorea chinensis), tu rui (Vatica diospyroides), cng vi cc loi gi ( Quercus spp), si(Lithocarpusspp), mc lan (Michelia sp.), Manglietia sp. v cc loi thuc h Long no nhLitsea spp, Cryptoccarya spp, Machilus spp


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- Tng A2: cy cao trung bnh 10 - 15 m, c khp tn cao. Ngoi cy tng A1 c mt y cn c cc loi khc nh: th (Dipspyros spp), cho (Engelhardtia sp.), nhi (Bischofiajavanica), c mui (Cipadessa baccifera), nh ni (Hydnocarpus clemensorum ), lng mang(Pterospermum sp), su (Celtis cinamomea), sn tr ( Eriobotrya poilanei), re (Cinnamomumbonii), xoan hi (Toona sinensis), lt ni (Koelreuteria sp.)

- Tng A3: gm c mt s loi cy cao st vi tng A2 nh rui r, my to, nh ni,

th (Diospyros spp ), ngt ( Gironniera subaequalis ), nhc (Polyalthia sp ), mc mt ( Clausenaspp ).

- Tng cy bi v thm ti pht trin kh, gm c mua (Melastoma spp),Phyllagathisspp, Syzygium spp,Boehmeria spp, han, dng x, gi hc (Leea sp.) v mt s loi cy thuc hThng tin (Gesneriaceae), h Bu b (Cucurbitaceae), h Khoai lang (Convolvulaceae).

b) Rng cy l rng thng xanh sn ni vi:V cu trc tng th:

- Tng A1: t khi c tng ny, c bit c loi nghin nh ln vi ng knh 70 - 80 cm.

- Tng A2 c khp tn cao, c chiu cao trung bnh 10 - 15 m. Nhiu loi cy ph bin

ca vng ni vi xut hin y nh: nghin, trai, inh, to vng, lng mang (Pterospermumheterophyllum), trm (Syzygium spp), th (Diospyros sp.), kho (Phoebe sp ), nhc (Polyalthiasp), thi ba (Alangium chinense). Tng A2 cng c nhiu cy c ng knh thn cyln hn 50cm nhng thng thp v chiu cao.

Hnh s 23. Rng ni vi thuc ai cao, Cao Bng. nh: Nguyn Ngha Thn


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Hnh s 24. Rng hn giao cy l rng vi cy l kim (bch xanh) Phong Nha - K Bng -nh: Nguyn Ngha Thn

- Tng A3 c chiu cao 5 - 10 m. Ngoi nhng cy nh ca tng A1, A2, y cn c:thnh ngnh (Cratoxylum formosum), dung (Symplocos

sp.), gi (Fagaceae sp.), hng b (Clausena sp.), chn chim vi (Schefflera pesavis),Picrasmajavanica, lt ni (Koelreuteria sp.)

- Tng cy bi thm ti c nhiu loi cy nh: ring (Alpiniasp), sa nhn (Amomum sp.),ry di (Alocasia sp.), han, lu (Psychotria spp),

gng (Randia spinosa), huyt gic (Dracaenacambodiarus), sm s (Memecylon sp.), c lo, thaokn (Helicteres sp.), thu tu (Aporosa sp.) v dng x.

Dy leo c cc loi thuc h To ta (Rhamnaceae), h Khoai lang ( Convonvulaceae).

c) Rng hn giao cy l rng, l kim ni vi :Kiu rng ny chim din tch nh phn b trn cc nh ni hoc nh ging ni.

khp tn khong 0, 3 - 0,4. Chiu cao trung bnh ca tng cy g thp : tng trn ch yu l ccloi cy a, sanh (Ficussp.), trm (Syzygium spp), chn chim vi, chn chim tm l (


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Scheffleraoctophylla), ho ni, du vi (Ulmus sp.), pt t (Pittosporum sp.). Trn ni vi tnh Qung Ninh cn c mt loi c hu l Schefflera halongensis. Ngoi cc loi cy lrng nh trn, cn c cc loi cy ht trn hn giao nh: cc loi tu (Cycas spp), hong n(Cupressus torulosa), hong n gi (Dacrydium elatum), kim giao (Nageia fleuryi), thng tre lngn ( Podocarpus pilgeri), thng P C ( Pinus kwangtungensis), du sam vi (Keteleeriadavidiana var. davaniana), sam bng sc nu (Amentotaxushatuyenensis), sam bng sc trng

(Amentotaxus yunnanensis), thng (Taxus chinensis), sam kim h ( Pseudotsuga chinensis), bch vng (Xanthocyparis vietnamensis). Hu ht chng l nhng cy g qu, c xp hngtrong sch v l i tng sn tm ca lm tc. Tng thp ch yu l cc loi cy nh thanhhng (Pistacia weimanifolia), cng (Calophyllum bonii), mc mt (Clausena indica), huytgic (Dracaena cambodiana), han, thu hi ng (Begonia sp.), m h (Mahonia nepalensis), cl tre (Setaria palmifolia) v.v Ngoi ra, cn c nhng loi tre na (Bambusa spp), Sasajaponica mc hn giao. Trong cu trc thm thc vt trn nh ni vi thuc ai cao, ni cnhng du hiu cho thy s chuyn tip t nhit i sang nhit i. Do , ngoi nhng loicy l kim nh trn th cc loi rng l v bn rng l xut hin l mt iu tt nhin. C th kn cc loi thuc h Gi (Fagaceae), cm (Elaeocarpus sp.), thch (Acer sp.), si (Balakatabaccata), b(Styrax sp.).

d) Rng ln cy l rngnh ni vi :Cu trc rng ch c mt tng vi nhng cy g nh chiu cao khong 6-10 m. y l

mt kiu thm thc vt rt c bit, c cc loi cy g nh ht trn nh: tu (Cycas spp), thitsam gi (Pseudotsuga chinensis),thit sam gi l ngn (P. brevifolia ), thit sam ng bc (Tsugachinensis) v.v Tng cy g nh gm c cc loi cy nh: hi ni (Illiciumgriffithii), cc loing gia b (Schefflera spp), d (Quercus spp),Lithocarpusspp, ch ni (Ternstroemiajaponica ), Pistacia weimanifolia. Ngoi ra cn c cc loi thuc h quyn (Ericaceae) nh:Rhododendronspp, Vaccinium dunalianum v cc loi re (Cinnamomum sp.), li ni (Jasminumlanceolarium), cng (Tirpitrzia sinensis) v.v Cy bi cn c cc loi cy nh: mua b ni cao,mm xi, ngy (Rubus spp), sm (Memecylon sp.). Thm ti v thc vt ngoi tng y c ccloi thuc h Phong lan (Orchidaceae), Ru (Bryophyta) v a y (Lichenophyta) cng vi cc

loi thuc h C ph (Rubiaceae) v cc loi cy dy leo ch yu lJasminum lanceolarium, kimcang (Smilax spp), h Nho (Vitaceae), bm bm (Entada sp.) v mng b (Bauhinia spp). y lni cn lu tr nhiu tim nng a dng sinh hc cn c quan tm khm ph v bo tn. Rtnhiu cc loi phong lan, c bit l lan hi c tm thy y l nhng pht hin mi cho khoahc, chng thuc cc chi: Bullbophyllum, Phajus, Cheirostylis, Gastrochilus, Liparis,Paphiopedilum, Renanthera. Ngoi ra cn c nhiu loi ht trn khc cng mi c pht hingn y nh bch vng, du sam vi v.v

e) Rng thsinh cy l rng ni vi:Kiu rng ny cng l hu qu tc ng ca con ngi i vi thm thc vt trn ni

vi ai cao. khp tn khong 0,3 - 0,4. Chiu cao trung bnh ca cy g tng u th sinh

thi: 15 - 20 m. Cc loi cy i din l: c mui, gi (Aglaia sp.), lt ni, xoan hi, b hn(Sapindus sp.), trm (Syzygium sp.), ho ni (Platycarya strobiacea) v.vRng th sinh nycn li ri rc cc cy g qu nh nghin, trai, cc loi inh v.v. Tng di tn gm nhng cyti sinh tng trn v qut hng b, thi tranh, dt snh (Pavetta sp.), hun lang (Wendlandia spp),thp t mnh (Decaspermum gracilentum), mn (Prunus spp) v.v Tng cy bi v thm tic nhiu loi pht trin mnh v rng tha. l cc loi cy nh mua b ni cao (Oxysporapaniculata), Melastoma spp, cc loi thuc h Thu Du (Euphorbiaceae), h Gai (Urticaceae),h C ph (Rubiaceae), h Thng tin (Gesneriaceae) v dng x. Dy leo c cc loi thuc hTo ta (Rhamnaceae), h Khoai lang (Convonvulaceae) v.v


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f) Trng cy bi trn ni vi ai cao:T thnh rng l cc loi cy a sng chu hn nh: bc bc (Mallotus spp), b cu v

(Breyniafruticosa), ngn (Cratoxylon formosum) v.v. Cc loi cy bi, cy tho thng gpl gng ( Randia spinosa), c lo, mua (Melastoma sp.), lau, cht, c tranh, vt, c rc(Microstegiumvagans), han, gai (Boehmeria spp), mua b ni cao, k

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