Phan Vung Sinh Thai Lam Nghiep o Viet Nam

Sec1:16 Phn vng sinh thi lm nghip Vit Nam

3Phn vng sinh thi lm nghip Vit Nam

Tng pht thi kh nh knh l nguyn nhn gy nn hin tng nng ln ton cu, lm bin i kh hu ro net trong nhng nm gn y v vn ny ang c tt c cc quc gia trn th gii quan tm. hn ch pht thi kh nh knh, ch yu l kh cc bon nc (CO2) mt mt cc nc pht trin cn cam kt gim pht thi, mt khc cn bo v pht trin rng, nht l cc nc nhit i ni tp trung ln din tch rng nhit i v l b hp th v lu tr kh cc bon nc. Vi ngha , ti Hi ngh cc bn ln th 13 (COP 13) din ra ti Bali, Indonesia vo thng 12/2007, cc bn lin quan thng qua K hoch Hnh ng Bali (Bali Action Plan) trong c xut l trnh xy dng v a REDD tr thnh mt c ch chnh thc thuc h thng cc bin php hn ch bin i kh hu trong tng lai, c bit l sau khi giai on cam kt u tin ca Ngh nh th Kyoto ht hiu lc vo nm 2012. REDD l vit tt cm t ting Anh: Reducing Emission from Deforestation and Forest Degradation in Developing Countries ngha l Gim pht thi do mt rng v suy thoi rng cc nc ang pht trin.

Vit Nam, REDD c thc hin thng qua 3 t chc ca Lin Hp quc l UNDP, FAO v UNEP v c gi tt l Chng trnh UN-REDD. Mt trong nhng mc tiu chnh ca UN-REDD Vit Nam l h tr Tng cc Lm nghip thuc B Nng nghip v Pht trin nng thn v cc c quan u mi thit lp c v qun l cc cng

01 t vn

4 Phn vng sinh thi lm nghip Vit Nam

c thc hin mt chng trnh REDD hiu qu, minh bch, cng bng. m bo rng cc c quan u mi c kh nng o lng gim pht thi t ph rng v suy thoi rng mt cch chnh xc v tun th ng cc tiu chun quc t.

Trong cc hot ng lin quan n tnh ton gim pht thi th vic xy dng mc pht thi tham kho (Reference Emision Level = REL) v h thng o m, lp bo co v thm nh (Measurement, Reporting and Verification = MRV) l ht sc quan trng. cp nh gi mc quc gia (Tier 1), cc tnh ton v hp th v pht thi ch yu da trn s liu v phn vng sinh thi ca cc kiu rng c bn ca Vit Nam. Trn c s cc kiu rng trong mt phn vng sinh thi c nng sut sinh hc tng i ng nht, chng ta c th tnh ton s b mc hp th/ pht thi ton quc cho lnh vc lm nghip.

Cho ti nay cha c h thng phn vng sinh thi lm nghip no ti Vit Nam. C chng ch l cc h thng phn loi rng, hay phn chia cc kiu thm thc vt rng, m khng nh v c cc kiu c phn b t nhin ti u? trung tm vng phn b, phm vi phn b, v d bo tim nng nng sut ca mi vng, ng vi mi kiu rng ra sao? Cc cu hi ny chnh l ni dung ca vic phn vng sinh thi lm nghip nhm mc ch lm c s cho vic xy dng cc Mc pht thi tham kho (REL), v o m, lp bo co, thm nh (MRV).

xy dng chin lc pht trin ngnh 10 nm, 15 nm, hay lp quy hoch lm nghip cho tng k hoch 5 nm khi cha phn vng STLN, ngnh lm nghip thng dng khi nim 8 vng kinh t lm nghip, xut hin vo u thp k 70 ca th k trc. T thp k 90, sau khi hp nht cc b Lm nghip, Nng nghip, Thy li, Ngnh lm nghip thng s dng c hiu qu h thng 7 vng sinh thi nng nghip, vi cc tiu ch xc nh v a hnh, kh hu, t ai, kiu rng.

Song, mt mt cc tiu ch v ch s v kh hu, thy vn, t ai, v.v, phn vng sinh thi nng nghip khc vi cc h sinh thi rng, cho d n c chung ngha v vng phn b v nng sut to ra sn phm nng lm nghip phc v nhu cu tiu dng ca x hi, s khc nhau ca h sinh thi rng ngoi sn xut sn phm tiu dng, li cn phi to ra mt dng sn phm quan trng hn na, l dch v mi trng sinh thi bo v s sng cn trn tri t, m REDD chnh l 1 dng dch v ang c ch gp phn chng bin i kh hu ton cu, trong Vit Nam v c vng lu vc sng M Kng c d bo l mt trong cc vng chu tc ng ln nht.

Ln u tin phn vng sinh thi lm nghip Vit Nam c thc hin trong hon cnh cc h sinh thi rng nguyn sinh b ph hy qu nhiu, li khng tin hnh


nghin cu kho st, tuy vy tha k c nhiu kinh nghim, nhiu s liu ca cc cng trnh phn vng ti Vit Nam v kh hu-thy vn, th nhng-lp a, a hnh-a cht, sinh thi nng nghip

Mc ch ca nghin cu ny l xy dng c s khoa hc v xut tiu ch phn vng sinh thi cho lnh th Vit Nam c c s ng nht tng i v cc kiu rng cho tng vng. S ng nht tng i ny v cc kiu rng c ngha quan trng trong vic gim sai s v tng tin cy trong qu trnh o m tr lng cc bon ca rng xy dng mc pht thi tham kho v thc hin MRV.

Trong cc phng php truyn thng c chn lc v tha k, trong trng hp ny phng php chuyn gia t ra rt hiu qu, nhng i hi cc nh sinh thi lm nghip c nhiu kinh nghim thc tin.


0202


2.1 Phn vng lnh th

2.1.1 C s php l

Nhng c s php l u tin ca nh nc v phn vng lnh th ca cc ngnh kinh t, cc ngnh chuyn mn t nhng nm 60, 70 ca th k trc l Thng t 193/UB/VP ngy 11/2/1963 ca Ban phn vng kinh t thuc y ban K hoch nh nc, v Quyt nh 270/CP ngy 30/9/1977 ca Hi ng Chnh ph, nay l Chnh ph hng dn v thc hin vic phn vng kinh t theo cc chuyn ngnh c th di y:

1. Kinh t 2. a l t nhin 3. a cht cng trnh 4. Kinh t ngnh 5. a l kinh t 6. Sinh thi nng nghip 7. Cc chuyn ngnh kinh t khc

02 Tng quan cc phn vng lin quan


Cc chuyn ngnh tin hnh phn vng da trn mt hoc nhiu phng n mc tiu, v s dng kt qu phn vng trong nhiu nm nay. Di y m t mt s phn vng c lin quan n nghin cu ny.

1) Phn vng kinh t ngnh: Phn chia lnh th t nc theo chiu dc thnh cc vng kinh t ngnh, lm cn c cho nh nc, t chc, qun l theo ngnh.

Phn vng kinh t ngnh nhm mc ch xc nh hp l phng hng pht trin ch yu ca ngnh trong vng, hin ti cng nh tng lai, kt hp ng n gia cc ngnh trong k hoch ha v trong t chc qun l nn kinh t quc dn theo ngnh v theo lnh th, phn vng kinh t ngnh cn l c s cho quy hoch vng kinh t.

C hai dng phn vng kinh t ngnh l phn vng cng nghip v phn vng nng nghip. Mi dng li chia ra cc phn ngnh nh trong cng nghip c phn vng khai thc than, du m, hi t, phn vng luyn kim en, v.v,.. cn trong nng nghip c phn vng trng trt, chn nui.

2) Phn vng a l t nhin: Ngnh a l t nhin chuyn nghin cu, pht hin h thng cc khu vc t nhin ng nht v pht sinh, do m c nhng c th ring, khng lp li trong khng gian.

C hai nhn t pht sinh ch yu, mt l nhn t a i chi phi bi s phn b nng lng mt tri khng ng u trn tri t, to ra cc vnh ai nng, n ha, lnh, v cc i rng, xa van, hoang mc. Hai l nhn t phi a i chi phi bi nng lng kin to trong lng t, hnh thnh cc chu lc, vng ni, cao nguyn, ng bng, cc min a cht - a hnh phn ha chi tit trong cc x.

Ti cc khu vc a l nh hn na, c s thng nht ca c hai nhn t, to nn cc tng th lnh th c s ng nht cao. Phn vng a l t nhin bao gm c hai khu phn v v phn loi. Ngoi phn vng tng hp ni trn cn c phn vng tng thnh phn a l t nhin nh phn vng a mo, phn vng kh hu thy vn, phn vng th nhng, phn vng sinh vt, cc phn vng ny s b sung cho nhau lm tng thm tnh khoa hc v tnh thc tin cho mi loi phn vng thnh phn.

3) Phn vng a l kinh t: Ngnh a l kinh t chuyn nghin cu v pht hin hoc d on s hnh thnh h thng cc vng kinh t hon chnh vi chc nng sn xut chuyn mn ha v pht trin tng hp. Da vo phn vng a l kinh t, nh nc c th nm c y tim nng v cc mt t nhin, kinh t, x hi


ca cc b phn lnh th khc nhau trn t nc nhm xc nh chin lc v cc chng trnh pht trin kinh t - x hi.

C phn vng a l kinh t tng hp, nghin cu lin ngnh pht hin cc vng kinh t a dng, phc tp, v c phn vng a l kinh t theo tng ngnh nh nng nghip, cng nghip, du lch pht hin cc vng chuyn mn ha hp.

4) Phn vng a cht cng trnh: Phn chia lnh th nghin cu theo cc iu kin a cht cng trnh. Thng s dng cc phn v min theo a kin to; vng - theo a mo; khu theo s phn b cc phc h a tng v ngun gc; khonh - theo mt trong nhng yu t c trng khc: Cc hin tng v qu trnh a cht ng lc cng trnh, a cht thy vn, tnh cht c l ca t , v.v.

Xet t hp cc iu kin a cht cng trnh nh gi mc thun li ca tng phn v i vi xy dng. Ty theo t l bn c thnh lp v c im ca lnh th, c th phn nh hn na cc phn v trn, hoc gp chng li. Bn phn vng c lp ring hoc biu th chung trn bn a cht cng trnh.

5) Phn vng kh hu thy vn: H thng phn v s phn vng kh hu da trn hai c trng, mt l phn ha v ti nguyn nhit, hai l phn ha v ti nguyn m. Hin nay ang s dng ph thng phn v hai cp l min kh hu v vng kh hu (Nguyn c Ng, 2008).

lMin kh hu: Phn nh theo ti nguyn nhit (bin /nm, tng bc x/nm); hin c hai min l min Bc v min Nam.

lVng kh hu: Trn mi min, theo ch tiu ma m (ma ma, ba thng ma cao nht) phn vng lnh th thnh 7 vng kh hu thy vn sau y: vng Ty Bc, vng ng Bc, vng ng bng Bc B, vng Bc Trung B, vng Nam Trung B, vng Ty Nguyn, vng Nam B.

6) Phn vng sinh thi nng nghip: B NN&PTNT phn chia lnh th Vit Nam thnh 7 vng phc v cho vic quy hoch, pht trin nng nghip. Cc vng sinh thi nng nghip gm: Trung du v min ni pha Bc; ng bng sng Hng; duyn hi Bc Trung B; duyn hi Nam Trung B; Ty Nguyn; ng Nam B v ng bng sng Cu Long.

Nh vy c s khc nhau trong vic phn chia lnh th theo ngnh chuyn mn so vi phn vng sinh thi nng nghip, hoc vng sinh thi lm nghip m chng ta ang nghin cu k c tn gi ca phn v c bn l vng, v d vng ng bng Bc B hay vng ng bng Sng Hng, v trong vng cn c h thng sng Thi Bnh.


2.1.2 Cp phn v v tn gi

Hin cha c s nht qun trong tn gi, s lng v khi nim ca cc cp phn v khng phi ch do mc ch ca s phn vng, m cn ty thuc vo quan nim v phng php ca tc gi hay nhm tc gi phn vng.Cc vn bn ni trn hng dn 7 cp phn v cnh quan sinh thi (CQST) t cp thp nht, l:

1. Din cnh quan sinh thi 2. Dng cnh quan sinh thi 3. Cnh quan sinh thi 4. Vng sinh thi 5. Khu sinh thi 6. Min sinh thi 7. X sinh thi

Trong thc tin, phn vng lnh th ca tng ngnh kinh t hay tng lnh vc chuyn mn, khng nht thit phi s dng 7 cp phn v k trn, m cn c mc ch ca vic phn vng. V d Phn vng a mo Vit Nam v cc nc ln cn ca L c An (1985) trn bn 1/1.000.000 dng 4 cp phn v v m v gi tn gn nh theo h thng hnh chnh l: I) Nc a mo; II) Tnh a mo; III) Min a mo; IV) Vng a mo.

Hi khoa hc t phn vng a l th nhng Vit Nam (1996) trn bn t l 1/1.000.000 cng dng 4 cp phn v v m v t tn st vi tn trong thng t 193/ UB-VP nm 1963 ca Ban phn vng kinh t l: I) 2 min; II) 6 min; III) 16 khu; IV) 142 vng.

2.2 Phn vng sinh thi

Phn vng sinh thi cng l mt dng phn vng lnh th nh va m t ti tit ti mc 2.1, nhng ni dung phn vng li l cc h sinh thi khc nhau.

2.2.1 Phng php lun trong phn vng sinh thi

Phn vng sinh thi c vai tr ht sc quan trng trong vic phn nh a l t nhin, khng gian mi trng, xc nh cc quy lut sinh thi c th ca tng vng, tiu vng. Phn vng hiu mt cch n gin l s phn chia lnh th thnh nhng n v nh hn, nhng c chung mt hoc mt vi tiu ch chn. C rt nhiu loi phn vng khc nhau, v d: Phn vng a l t nhin; phn vng a cht; phn vng kh


hu; phn vng thy vn; phn vng sinh thi nng nghip, lm nghip, thy li, v.v.Trong tng quan ny s tng hp cc h thng phn vng lm nghip t trc n nay lm c s la chn cc tiu ch phn vng sinh thi lm nghip Vit Nam. Trc ht, cn phi tm hiu mt s khi nim lm c s cho vic phn vng sinh thi:

lCnh quan sinh thi l tng th lnh th hin ti, c cu trc cnh quan a l v c chc nng sinh thi ca h sinh thi (HST) ang tn ti v pht trin trn .

lCu trc ca cnh quan sinh thi gm c cu trc ca cnh quan v cu trc ca HST lng vo nhau trong mt th thng nht. V d v cu trc cnh quan: nn , a hnh, th nhng, sinh vt, thy vn, kh hu; v cu trc HST: vt cht v c, hu c, sinh vt sn xut, sinh vt tiu th v sinh vt phn hy.

lDng cnh quan sinh thi c c trng bi s ng nht nn v cc th hnh thi v tiu hoc trung a hnh n gin; tiu hoc kh hu a phng; cc c im thy vn quy m tng ng; cc n v t; cc qun x

thc vt.

lChc nng sinh thi l s vn ng v bin i vt cht, nng lng v hnh thi ca cc thnh phn cu trc trn. V d: ngn ni, ng bng, cc m hnh sn xut nng nghip, lm nghip, v.v.

lVng sinh thi l mt n v lnh th c cu trc ng nht tng i bi tnh tri pht sinh ca mt kin trc a cht thuc mt i a cht; Tp hp cc th hnh thi i a hnh c c trng tng hp tt c cc hp phn t nhin: kh hu, thy vn, th nhng, sinh vt, v.v,.. v d: vng sn xut nng nghip, lm nghip, ng nghip, v.v.

lKhu sinh thi c hnh thnh bi mt i cu trc a cht c chung lch s pht trin v c im kin to l tp hp cc th hnh thi i a hnh ln hn vng sinh thi, c cng c im v kh hu, thy vn, th nhng, sinh vt, v.v,.. v d: vng kinh t, tnh, v.v.

lMin sinh thi c hnh thnh trong min a cht hay khu vc a cht c chung c im ca cu trc lp v tri t chi phi cc min kh hu v cng vi thm thc vt ng vi min kh hu . V d: min xch o, n i,

nhit i, v.v.

lX sinh thi: L cp phn v ln nht, quy m lc a v i dng c c trng bi phn lnh th gm nhiu min sinh thi. X sinh thi thng cp n tng lc a.

lH sinh thi l n v c bn ca cnh quan t nhin. Theo Odum, h thng cnh quan t nhin bao gm bn kiu h sinh thi c bn: I) Cc h thng sn xut, din th c con ngi kim sot lin tc nhm duy tr mc nng


sut cao; II) Cc h thng bo tn hay t nhin, ni cho phep hay to iu kin cho qu trnh din th t nhin tin ti trng thi bn vng; III) Cc h thng lin hp, trong kt hp c hai kiu trng trn; v IV) Cc h thng th v khu cng nghip hay nhng khu vc khng tht quan trng v mt sinh hc.

Trn th gii c cc dng phn vng nh sau: I) Phn vng sinh thi phc v cho nghin cu cc h sinh thi v khai thc ti nguyn; II) Phn vng cnh quan tng hp cc vn c lin quan n vic nghin cu cc nguyn nhn phn ha v tch bit ca mi trng a l (N.I. Mikhailov, 1955). L s phn chia b mt tri t m trong khu vc c phn chia gi nguyn tnh ton vn lnh th v s ng nht bn trong bt ngun t s chung nht ca s pht trin, v tr a l, qu trnh a cht(A.G. Ixatsenko, 1965); III) Phn vng a l t nhin l vic hp nht cc lnh th hoc thy vc tng i ng nht v mt du hiu c tha nhn mt mc nht nh v tch chng ra khi nhng khu vc khng c du hiu ; IV) Phn vng kinh t l s phn chia lnh th thnh h thng cc loi vng v cp vng kinh t khc nhau nhm mc ch xc nh ng n phng hng pht trin kinh t x hi ca vng.

Phn vng mang nhng c tnh l: I) tnh ton vn lnh th (khng lp li); II) tnh c nh ranh gii (c th xc nh hoc khng); v III) tnh ch quan trong phn vng th hin mc ch ca phn vng theo thc mong mun ca con ngi.

Phn vng phi bo m cc nguyn tc: I) C s ng nht tng i ca s phn ha cc ch tiu phn vng; II) C s la chn cc nhn t tri trong khi xem xet cc biu hin mang tnh n nh ca HST t nhin; III) Bo m ton vn lnh th tin cho vic khai thc, bo v v qun l vng.

2.2.2 Nhng cng trnh phn vng sinh thi Vit Nam

1) Phn vng sinh thi t trng ng (Trn An Phong v nnk, 2000). Lnh th t lin Vit Nam c chia thnh 3 min v 9 vng.

2) Phn vng sinh thi thy li min Trung (Vin thy li min Nam, 2008) phn chia min Trung thnh 4 vng sinh thi l: Ct ven bin, ng bng, g i trung du, ni cao.

3) Phn vng sinh thi nng nghip vng ng bng Sng Hng (Cao Lim, 1990). Trong 3 loi t l bc mu, chua mn, ng trng, phn chia 8 vng, 13 tiu vng, th hin trn bn t l 1/250.000.

4) Phn vng sinh thi nui trng thy sn 8 tnh ven bin ng bng sng Cu Long (HQG TP HCM) trn bn t l 1/250.000 n 1/100.000 v.v.


5) c s dng hiu qu v rng ri nht l cng trnh Phn vng sinh thi nng nghip.

S phn chia lnh th thnh cc vng sn xut nng nghip khc nhau, da trn c s cc iu kin sinh thi nh t, nc, kh hu khc nhau. Phn vng sinh thi nng nghip to c s cho vic s dng ti nguyn nng nghip c hiu qu ti u, pht huy y tim nng ca tng vng nhm la chn ng cc loi hnh s dng t nng - lm nghip.

Vit Nam hon thnh vic phn vng sinh thi nng nghip, ton lnh th c chia thnh 7 vng l: min ni v trung du Bc B, ng bng sng Hng, duyn hi Bc Trung b, Duyn hi Nam Trung B, Ty Nguyn, ng Nam B v ng bng sng Cu Long.

Phn vng sinh thi nng nghip Vit Nam lm c s tt cho vic xy dng quy hoch tng th cc vng kinh t cng nh quy hoch s dng t ca cc tnh trong ton quc.

Phn vng sinh thi nng nghip gn kt rt cht ch vi phn vng sinh thi lm nghip, v i khi c s dng cho quy hoch pht trin lm nghip. Tm vng lm nghip ch khc 7 vng sinh thi nng nghip l c thm vng Ty Bc (Bc B), song vn ang cn nghin cu tip l s pht sinh v pht trin ca cc h sinh thi rng khc vi cc h ngn ngy ca cy lng thc v bn thn HSTR cn phi cung cp dch v bo v mi trng, cn c la chn tiu ch khc v phn v khc vi phn vng sinh thi nng nghip.

2.3 Phn vng sinh thi lm nghip

Cho n nay, cha c cng trnh xy dng c h thng phn vng STLN, nn vn tm dng 8 vng lm nghip, m khng gi tn l vng sinh thi, hay vng kinh t. Nm 2006 khi xy dng Chin lc pht trin lm nghip giai on 2006-2020 th sp nhp vng Trung Tm vi vng ng Bc (Bc B) v khng cn cn thit gi li mt vng Trung tm c cc tiu ch v kh hu, t ai, a hnh gn tng t vi vng bn cnh, m ch u tin pht trin trn di 100.000 ha rng nguyn liu cho nh my giy Bi Bng, nn ch cn 8 vng lm nghip. H sinh thi rng bao gm cc kiu thm thc vt rng trong c nc c phn chia v s dng theo cc phng php, cc mc ch khc nhau, m s trnh by k trong tit trong mc 3.2 phn tip theo. Cho ti nay, cha c cng trnh phn vng STLN no Vit Nam c thc hin, v vy quan tm u tin l c s khoa hc ca Phng php lun trong phn vng sinh thi c trnh by ti mc 4.


0303


033.1 Gii thiu v rng v ti nguyn DSH

3.1.1 Nhng nhn t nh hng v phn b t nhin ca rng

Lnh th Vit Nam nm hon ton trong ai nhit i, v thuc vng c kh hu gi ma. Tuy vy, cc kt qu nghin cu phn vng kh hu t nhin li cho thy c s chnh lch ng k v cc tiu ch chi phi s pht sinh, pht trin ca cc h sinh thi rng, v h sinh thi nng nghip, l: tng nhit nm, bin ngy v bin nm, c 1 ma ng. Cc tiu ch ny to ra s chnh lch ng k v kch thc (ng knh, chiu cao, th tch cy, tr lng g v sinh khi, c bit l cc h sinh thi rng hn loi thng xanh nhit i v h sinh thi rng ngp mn.

Trong khi nhn t v v nhn t a i nh hng khng ro rt n cc h sinh thi rng v nng sut sinh hc ca chng, th s chnh lch theo cao li c nh hng ln ti vic hnh thnh cc h sinh thi n i ni cao (cc kiu ph theo cao), v nng sut sinh hc ca chng, thng qua nhit , lng ma, gi chiu sng, th nhng, a mo. M t chi tit v cc kiu rng c nu trong mc 3. Ba phn t din tch lnh th Vit Nam l i ni, trong phn b thc vt t cao

03Thm thc vt rng Vit Nam v c trng phn b


1.000 m l c thay i ro net, trong khi cc dy Bi-p, Ch-yang-sin, Ngc Linh min Nam c cao trn 2.000 m, cn min Bc th nhiu dy ni tng t hoc cao hn v cao nht l dy Hong Lin, c nh Phan-xi-png cao khong 3.143 m.

Nm 1943 din tch rng Vit Nam ln u tin c cng b l 14,3 triu ha (P. Mau-rant, 1943), khi ton b din tch rng l rng t nhin v a s l rng nguyn sinh. Qua hai cuc chin tranh 1945 -1954, v 1965-1975 din tch rng Vit Nam gim xung cn 11,2 triu ha. Tc gim din tch rng nhanh nht l 15 nm sau khi t nc thng nht (1975) v n nm 1990 din tch rng t mc thp nht l 9,17 triu ha, chim khong 64% din tch rng thng k vo nm 1943. T nm 1990 tr i, thng qua cc chng trnh 327, d n trng mi 5 triu ha rng v iu kin gim thiu sc ep lng thc, ci t, nn din tch rng tng ln 11,3 triu ha vo nm 2000 v 13,3 triu ha nm 2009, t xp x 93% din tch rng ban u. Tuy nhin, din tch rng tng ch yu l 3 triu ha rng trng, cn rng t nhin phc hi chm hn, cc h sinh thi nguyn sinh ch cn li trong vng loi ca cc khu bo tn hoc cc vn quc gia. Bng 1 ch ro xu th thay i din tch rng ca Vit Nam trong 60 nm qua.

Bng 1. S thay i din tch rng Vit Nam, 1943 - 2011

Nm Din tch rng, triu ha T l che

%

Ha/

ngi

Thay i so vi 1990

T nhin Trng Tngha %

1943 14.300 0 14.300 43,0 0,70

1976 11.077 92 11.169 33,8 0,22

1980 10.186 422 10.608 32,1 0,19

1985 9.038 584 9.892 30,0 0,16

1990 8.430 745 9.175 27,8 0,14

1995 8.252 1.050 9.302 28,2 0,12 +127 +0,4

2000 9.444 1.471 10.915 33,2 0,14 +1.740 +5,4

2005 10.283 2.334 12.617 36,4 0,15 + 3.442 +8,6

2009 10.339 2.920 13.259 39,1 0,15 + 4,084 + 11,3

2011 10.285 2.852 13.515 39,7 0,15 +4.340 +11,9

Ngun: Tng cc Lm nghip, 2012


Tng tr lng g cng ging nh tng sinh khi cy sng u c chung quy lut gim trong thi gian ni trn, nhng phc hi th li chm hn. Nm 1990 tng tr lng g l 657 triu m3, nm 2000 l 782 triu m3 v nm 2005 l 812 triu m3.

Khi phn vng STLN th tng tr lng g s c thng k theo vng, nhng n ch phn nh khi lng hin trng ca rng, ch cha th d bo tim nng nng sut ca cc h sinh thi s c phc hi. Bng 2 l kt qu kim k nm 2005 v tr lng g ca cc loi rng theo 8 vng sinh thi.

Hng

mc

Ton

quc

Ty Bc ng

Bc

ng

bng

Sng

Hng

Bc

Trung

B

Nam

Trung

B

Ty

Nguyn

ng

Nam

B

ng

bng

sng

Cu

Long

Tng 811.678 43.030 65.777 4.763 192.321 145.714 288.559 66.005 5.509

RTN 758.134 41.320 50.332 3.152 183.274 130.436 285.663 63.186 770

% RTN 93,4 96,0 76,5 66,2 95,3 89,5 99,0 95,7 14,0

RT 53.545 1.710 15.444 1.611 9.048 15.278 2.896 2.819 4.739

% RT 6,6 4,0 23,5 33,8 4,7 10,5 1,0 4,3 86,0

Bng 2. Tr lng rng g theo cc vng sinh thi (1000m3)

Ngun: Tng cc Lm nghip, 2010

3.1.2 Ti nguyn DSH rng

iu kin sinh thi c nh hng quyt nh n tnh a dng ca HSTR. Lnh th lc a Vit Nam tri di t v tuyn 8O35 Bc n v tuyn 23O24 Bc, pha Nam tip cn gn vi vng xch o, pha Bc gip vi ai nhit i. Vit Nam c kh hu nhit i gi ma, c ma ng lnh v cn xch o. B bin di 3.260 km t Mng Ci n H Tin, ni c rng ngp mn, ni c rng phi lao trn ct. a hnh i ni chim ba phn t lnh th, t vng ven bin n ng bng, trung du, cao nguyn, vng ni. Chnh iu kin a hnh ny lm cho Vit Nam khng ch c kh hu nhit i gi ma m cn c c kh hu nhit i v n i ni cao. Khng k min kh hu bin ng, kh hu lc a c 3 min kh hu (pha Bc, ng Trng Sn, pha Nam) vi 10 vng kh hu c trng cho cc vng sinh thi khc nhau (Phm Ngc Ton, Phan Tt c, 1978). 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 nh t Feralit, t nu v t en nhit i, v.v. m cn c c lp t nhit i, lp t ph nhit i vng ni v c t vng alt ptzn ho trn ni cao.


Tnh DSH ca rng Vit Nam c nh gi l rt cao, khng ch trong vng m c trn th gii. V khu h thc vt, ngoi nhng yu t bn a, c hu, Vit Nam cn l ni hi t ca 3 lung thc vt di c t Trung Quc, n - Himalaya, Malayxia - Innxia v cc vng khc k c n i.

Tnh a dng v loi cy v ng vt l mt trong nhng nhn t quyt nh tnh a dng v h sinh thi rng t nhin ca Vit Nam (Phng Ngc Lan, 2006). V khu h thc vt, ngoi nhng yu t bn a, c 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 (2008), nc ta c khong 19.357 loi thc vt thuc 2.524 chi v 378 h, trong c 1.600 loi nm, 368 loi vi khun lam, 2.175 loi to, 793 loi ru, 2 loi khuyt l thng, 57 loi thng t, 2 loi thn t (c thp bt), 691 loi dng x, 69 loi ht trn v 1.300 loi ht kn. Cc nh thc vt hc d on con s loi thc vt nc ta cn c th ln n 25.000 loi. Trong cc loi cy ni trn c khong 15.000 loi thc vt c mch, s loi thc vt c hu ca Vit Nam chim khong 30% tng s loi thc vt min Bc v chim khong 25% tng s loi 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 mang li cho rng Vit Nam nhng gi tr to ln v kinh t v khoa hc. Theo thng k ca Vin Dc liu (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 loi cy cho nha thm, 600 loi cy cho tananh, 500 loi cy cho tinh du v 260 loi cy cho du beo.

V ng vt, theo t liu ca IUCN/CNPPA (1986) khu h ng vt Vit Nam kh giu v thnh phn loi v c mc cao v tnh c hu so vi cc nc trong vng ph ng Dng. Trong s 21 loi kh c trong vng ph ny th Vit Nam c 15 loi, trong c 7 loi v phn loi c hu (Eudey 1987). Theo Mackinon, trong vng ph c 49 loi chim c hu th Vit Nam c 33 loi trong c 10 loi c hu ca Vit Nam. Nm 2008, Nguyn Ngha Thn thng k c s lng cc loi ng vt Vit Nam l 9.325 loi, trong c 5.500 loi cn trng, 2.476 loi c, 800 loi chim, 80 loi lng c, 180 loi b st v 295 loi th.


3.2 Cc h sinh thi rng, c s khoa hc ca phn loi v p dng

3.2.1 Khi nim v HSTR

Sinh thi hc (Ecology), theo Hu Th (2010), bt ngun t ch Hy Lp Oikos c ngha l ni sng, nh , Logos l mn hc, khoa hc. Theo ngha ny n l khoa hc v ni ca sinh vt.

t lu trong thc ca nhiu nh khoa hc v trong mt s cng trnh ca mnh c ni dung sinh thi hc. V d trong cng trnh ca Conrad von Gesner (1555), cng trnh ca J.Ray (1717), A.v.Haller (1732), J.P.de Tournefort (1727) ch ra nh hng ca cao v v n phn b ca cc loi thc vt. J.G. Gmelin (1750) so snh s ging nhau v khc nhau ca h thc vt vng Siberi vi vng ni chu u. P.S. Pallas (1741) ch ra s ph thuc ca mt s thm thc vt vo kh hu. C.L. Willdenow (1792) ch ra mi quan h gia thc vt vi mi trng. ng tm cch chia chu u thnh cc tnh h thc vt khc nhau, nhng mi n nm 1823 J.F. Schouw mi hon thnh cng trnh chia thm thc vt trn tri t thnh cc vng (tnh).

Cng trnh a thc vt (Geobotanik) ca A.F. Humboldt (1807) Ideen zu einer Ge-ographie der Pflanzen cp rt su v mi quan h gia thm thc vt vi cc yu t mi trng. Cng trnh ca J.Liebig (1840, 1843) ch ra mi quan h gia phn bn vi nng sut mt s cy trng. T cng trnh ny tc gi a ra nh lut ti thiu, mt trong nhng nh lut c bn ca sinh thi hc hin i. Tuy nhin thut ng sinh thi hc (Ecology) ch mi xut hin ln u tin vo nm 1858 trong bc th ca nh vn ngi M Henry David Thoreau v n nm 1866 n mi c E.Haeckel a ra nh ngha trong cun sch v hnh thi chung ca cc c th. Theo tc gi th sinh thi hc l khoa hc chung v mi quan h gia sinh vt v mi trng. T nm 1870 tc gi chnh l b sung lm sng t thm nh ngha sinh thi hc.

Bn cnh nh ngha ca E.Haeckel a ra, cn nhiu nh ngha khc nh nh khoa hc M F.Clement (1920) cho rng: Sinh thi hc l khoa hc v cc quan h. Nh sinh thi hc cng ngi M H.T.Odum (1959) a ra nh ngha: Sinh thi hc l khoa hc nghin cu v cu trc ca thin nhin. Nh khoa hc X Vit X.Svartx (1972) nh ngha: Sinh thi hc l khoa hc v cc quy lut iu khin i sng ca thc vt, ng vt trong mi trng sng t nhin. Chng ta gp rt nhiu nh ngha tng t trong cc cng trnh nghin cu khc nhau. iu chung nht ca cc nh ngha l mi quan h tc ng ln nhau gia


sinh vt v mi trng. y chng ti theo nh ngha sau: sinh thi hc l mt hp phn ca khoa hc v s sng, l khoa hc nghin cu cc iu kin sinh tn v pht trin ca sinh vt, cc mi quan h tc ng qua li gia sinh vt vi mi trng v gia sinh vt vi nhau trong qu trnh tn ti pht trin v tin ho ca chng. y con ngi c coi l yu t sinh vt, nhng l nhn t c bit, bi l n c tnh cht x hi cao m khng mt sinh vt no c c. Mt khc con ngi hin i lm bin i c bn mi trng. Do con ngi t n vt ra khi phm vi khi nim mi trng nguyn thu v ng v tr c lp trong h thng t nhin - con ngi. Cng t y xut hin sinh thi hc nhn vn (Human Ecology). Con ngi l i tng trung tm trong h sinh thi ny, mi nghin cu u hng ti phc v li ch cao nht ca con ngi. Cng cn nhn mnh rng d con ngi c tin b n u cng khng th tch mnh khi t nhin. Nu tch con ngi ra khi t nhin con ngi s b dit vong. Cch y gn 50 nm nh khoa hc Php vit .... con ngi mc phi mt sai lm rt ln khi ln mt cho rng c th tch ri khi thin nhin v pht l cc quy lut ca n. Gia con ngi v mi trng t nhin bao quanh n t rt lu c s gin on. Bn hip c c gn b ngi nguyn thu vi ni sinh sng ca n b mt bn l con ngi hu b ngay sau khi n t cm thy mnh t v sau ch tha nhn cc quy lut do chnh n ra. Cn phi xem xet li hon ton quan im v k kt mt hip c mi vi thin nhin - hip c mang li cho con ngi kh nng sng hi ho hon ton vi thin nhin (Trch theo V.Dejkin 1985). Sinh thi hc ang chun b vn bn cho hip c . Trong cng trnh ny, sinh thi hc cng c hiu l khoa hc v mi quan h gia sinh vt v mi trng.

3.2.2 Cc cp bc (hp phn) ca sinh thi hc

T bc c th tr ln, cc nh sinh thi hc kinh in chia sinh thi hc thnh 5 cp (theo R.Schubert 1986, H.J. Mueller 1988) theo trnh t t thp n cao:

l C th (Autecology) thut ng do J. Schroeter a ra nm 1896.

l Qun th (Populationecology = Demecology) do F.Schwerdtfeger, 1968

l Qun x (Biogeocenos = Synecology= community) do Schroeter, 1902.

l Qun h hay H sinh thi (Ecosystem= Biome)

l Sinh quyn (biophere).

Do ting Vit c bin dch t ting hn, nn kh nh, kh phn bit cc cp bc. iu cn nh y l n v cp qun x (biogeocenos hoc community), v cp bc qun h hay h sinh thi, l cc n v c s dng thng xuyn.


iu khc bit gia sinh thi hc c th v sinh l hc cn c nhn mnh l: STH c th nghin cu phn ng ca ton b c th sinh vt vi mi trng, cng ngc li, sinh l hc nghin cu phn ng ca tng b phn c th sinh vt (theo Dng Hu Thi, 1998). Tt nhin sinh l hc lun gn vi nhau.

Hin nay cng c nhiu tc gi cho rng ch c khi nim mi trng, ch khng c khi nim mi trng sinh thi. Th nhng H.J.Mueller (1988) phn bit rt ro khi nim mi trng (Umwelt, Environment) vi mi trng sinh thi (Oekologis-che Umwelt).

3.2.3 Cc HSTR ch yu Vit Nam

Tr cc HSTR thun loi c cu trc gin n, chim t trng din tch nh trn lnh th nh rng l kim, rng trm, rng tre na, v nay c thm cc HST rng trng, a s rng nhit i l rng hn loi, rng hn loi nguyn sinh hoc t b tc ng, rt cn cho nghin cu d bo nng sut sinh hc u ch cn phn b trong cc khu Bo tn thin nhin, vn quc gia, nhng ni cha m mang ng x, v vng su, vng xa, ni cao ho lnh. Di y tng hp cc h sinh thi rng t nhin in hnh:

1. H sinh thi rng kn thng xanh ma m nhit i (Evergreen closed tropical humid forest)

Nhng h sinh thi rng thuc kiu thm thc vt ny rt phong ph v a dng, phn b cc 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, Tha Thin Hu, Qung Nam, Ty Nguyn, v.v. Phn b theo cao so vi mc nc bin cho thy HSTR ny phn b cao di 700 m min Bc v di 1.000 m min Nam.

HSTR ny thng c cu trc tng th c 5 tng:

l Tng vt tn (Upper storey) A1: cy g cao n 40 - 50 m, thuc h Du (Dip-terocarpaceae), h Du tm (Moraceae), h u (Leguminosae), v.v.

l Tng u th sinh thi (Ecological dominance storey) A2: phn ln l nhng loi cy thng xanh thuc cc h D (Fagaceae), h Re (Lauraceae), h Vang (Caesalpini-aceae), h Trinh n (Mimosaceae), h Cnh bm (Papilionaceae), h B hn (Sapin-daceae), h Xoan (Meliaceae), h Mc lan (Magnoliaceae), h Trm (Burseracea e), v.v.


l Tng di tn (Lower storey) A3: cao t 8 - 15 m, mc ri rc di tn rng, thuc cc h Ba (Clusiaceae), h Du (Ulmaceae), h Mu ch (Myristicaceae), h Na (Annonaceae), h Mng qun (Flacourtiaceae), v.v.

l Tng cy bi (Bushes storey) B: cao t 2 - 8m, thuc cc h C ph (Rubiaceae), h Trc o (Apocynaceae), h Cam qut (Rutaceae), h Na (Annonaceae), h Mua (Melastomaceae), h Nhn sm (Araliaceae), h Thu du (Euphorbiaceae,v.v.

l Tng c quyt (Climber storey) C: cao khng qu 2 m. thuc cc h r (Acan-thaceae), h Gai (Urticaceae), h Mn ry (Araceae), h Gng (Zingiberaceae), h Hnh ti (Liliaceae) v nhng loi dng x, v.v.

Cc kiu ph min thc vt trong HSTR ny gm:

l Khu h thc vt Nam Vit Nam Malaixia Innxia (Flora of Sothern Vietnam Malaysia and Indonesia), u hp h Du (Dipterocarpaceae):

c trng c bn d nhn bit ca kiu ph ny l u th ca cc loi cy h Du (Dipterocarpaceae) cc tng trn. 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 (Vatica tonkinensis), Tu mui (Vatica fleuryana), Ch en (Parashorea stallata), v.v. min Nam, c bit l Ty Nguyn, loi cy tiu biu cho h Du l Du ri (Dipterocarpus alatus), Du ng (Dipterocarpus turberculatus).

Ngoi cy h Du (Dipterocarpaceae), cn c nhng loi cy bn a thng xanh thuc cc chi: G (Sindora), Rng rng (Ormosia), Mung (Cassia), v.v, thuc h u (Leguminosae); D (Lithocarpus), D (Castanopsis), Si (Quercus) v.v, thuc h D (Fagaceae); Trm (Syzygium), Eugenia thuc h Sim (Myrtaceae); Tr (Camellia), Hung nng (Terstoemia), Vi thuc (Schima) thuc h Ch (Theaceae); Ba (Garcinia), Vp (Mesua), C l (Calophyllum) thuc h Ba (Clusiaceae); Su (Dracotomelum), Xoi m (Bouea), v.v, thuc h Xoi (Anacardiaceae); Gi (Aglaia), Gi gc (Aphanamixis), Chc kh (Dysoxylon), Quych (Chisocheton) thuc h Xoan (Meliaceae).

Cc u hp (dominant groups) chnh bao gm: u hp Sao en (Hopea odorata); u hp Kin kin (Hopea pierrei); u hp Ch ch ( Parashorea chinensis); u hp Ch nu (Dipterocarpus tonkinensis); u hp Du ri (Dipterocarpus alatus); cc u hp tu (Vatica sp.); u hp Vn vn (Anisoptera costata).

l Khu h thc vt Bc Vit Nam - Nam Trung Hoa (Flora of Northern Viet nam South of China): Kiu ph min ny thng vng thp, min Bc di cao 700 m so vi mc nc bin v trn ng ng nhit thng lnh nht 20oC; min Nam vng thp m, cao di 1.000 m so vi mc nc bin thuc dy Trng Sn.


Cc u hp chnh bao gm: u hp h Re (Lauraceae); u hp h D (Fa-gaceae); u hp h Xoan (Meliaceae); u hp h Du tm (Moraceae); u hp h Mc lan (Magnoliaceae); u hp h u (Leguminosae); u hp h Xoi (Anacardiaceae); u hp h Trm (Burseraceae); u hp h B hn (Sapin-daceae); u hp h Hng xim (Sapotaceae), v.v.

2. H sinh thi rng kn na rng l m nhit i (Semi-deciduous closed tropical humid forest)

H sinh thi rng ny phn b Qung 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. Theo cao so vi mc nc bin, HSTR ny thng phn b di 700m min Bc v di 1.000 m min Nam.

Cu trc rng gm tng cy g (A1, A2 v A3). in hnh l hai loi cy rng l: Sng l (Lagerstroemia tomentosa ) v Sau sau (Liquidambar formosana). Ngoi ra cn c cc loi cy thuc h Du (Dipterocarpaceae), Xoan (Meliaceae), u (Legumino-sae), a tch (Datiscaceae), Du tm (Moraceae), o ln ht (Anacardiaceae), Bng (Combretaceae), Long no (Lauraceae), Trm (Burseraceae), Nhn (Sapindaceae), v.v. Chiu cao qun th t n 40 m, nhiu loi cy c bnh v. Cc kiu ph min gm: l Kiu ph min thc vt thn thuc vi khu h Malaixia - Innxia v khu h

n - Myanma: Kiu ph ny pht hin Mng Xen, 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) . Ngoi ra cn c nhiu loi cy rng l khc nh cc loi d (Quer-cus acutissima, Quercus serrata, Quercus griffithii), B (Styrax tonkinensis), Xoan ta (Melia azedarach), Lim xt (Peltophorum tonkinensis). C qun th t thnh loi cy rng l gn nh thun loi nh Sng l (Lagerstroemia tomen-tosa) Con Cung (Ngh An), Sau sau (Liquidamba formosana ) Hu Lng (Lng Sn) v Bin ng (Bc Giang) Khu h thc vt Vit Nam c nhiu loi cy rng l thuc cc h: h Du (Dipterocarpaceae), h u (Leguminosae), Bng (Combretaceae), a tch (Datiscaceae), Trm (Sterculiaceae), o ln ht (Anacardiaceae), Xoan (Meliaceae), Nhn (Sapindaceae), inh (Bignoniaceae), Du (Ulmaceae), Du tm (Moraceae), C roi nga (Verbenaceae).

l Kiu ph min thc vt thn thuc vi khu h bn a Bc Vit Nam - Nam Trung Hoa v khu h di c n - Myanma: Kiu ph min ny c cc loi cy rng l thuc cc h Xoan (Meliaceae), Nhn (Sapindaceae), u (Leguminosae), Xoi (Anacardiaceae), D (Burseraceae), C roi nga (Verbenaceae).


3. H sinh thi rng l rng thng xanh trn ni vi (Evergreen broad leaved forests on limestone)

Ni vi phn b trong 24 tnh v thnh ph nhng ch yu tp trung cc tnh pha Bc v Bc Trung B. 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. C th 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 v vng qun o.

Phn b theo v th HSTR ny phn b t H Tin n Cao Bng (23oB), ch yu t Qung Bnh (17oB) tr ra. Phn b theo ai cao t vi chc met ln n 1.200m so vi mc nc bin. Cu trc tng th v t thnh loi cy kh phong ph. C th chia HSTR ny theo cao nh sau:

3.1. Rng ni vi ai thp di 700m (Forests on limstone below 700m)

a) Rng kn thng xanh chn ni vi (Evergreen closed forest on foot of lime-stone): Cu trc rng phc tp, c 5 tng:

l Tng vt tn (A1): Cy cao trn 40 m thuc cc h Leguminosae hay Combretaceae, Dipterocarpaceae v cc loi ph bin nh: Su (Dracontomelum duperreanum), Thung (Tetrameles nudiflora), Sng (Pometia pinnata), Ch nhai (Anogeissus acuminata).

lTng u th sinh thi (A2): gm nhng cy g cao t 20 n 30m thuc cc h: D (Fagaceae), Long no (Lauraceae), Vang (Caesalpiniaceae), Trinh n (Mimosaceae), u (Fabaceae), B hn (Sapindaceae), Mc lan (Magnoliaceae), Xoan (Meliaceae) v cc loi Sao xim (Hopea siamensis), Mu ch (Knema sp), Sao (Hopea sp).

l Tng di tn (A3): gm nhng cy cao di 15 m, mc ri rc thuc cc h: Ba (Clusiaceae), Du (Ulmaceae), Na (Annonaceae) cng vi cc chi: L ni (Hydnocarpus sp.), Trm (Sterculia sp.), Mang (Pterospermum sp.), Du da (Baccaurea ramiflora) v cc loi c trng Rui r (Streblus ilicifolius), My to (Streblus macrophyllus), v.v.

l Tng bi (B): gm nhng cy bi, g nh cao di 8 m thuc cc h: Trc o (Apocynaceae), C ph (Rubiaceae), Mua (Melastomataceae), Ng gia b (Araliaceae), Thu du (Euphorbiaceae), r (Acanthaceae), v.v.

l Tng thm ti (C): gm cc cy thn tho thp (di 2 m) thuc cc h: Ar-aceae, Acanthaceae, Urticaceae, Zingiberaceae, Begoniaceae, Convallariaceae, v.v.


Thc vt ngoi tng gm dy leo thuc cc h: Nho (Vitaceae), u (Fabaceae), Mng g (Connaraceae) v cc cy b sinh, k sinh thuc h Phong lan (Orchi-daceae), Tm gi (Loranthaceae), h Ry (Araceae),v.v.

b) Rng thng xanh sn ni vi (Evergreen forests on limestone slopes):

Cc loi cy ca rng thng xanh sn ni vi gm c: Rui r (Streblus ilici-folius), My to (Streblus macrophyllus), Qut hng b (Clausena lansium), Lng tong (Walsura sp.), Arytera sp, Su (Celtis sp.), Trai (Garcinia fagraeoides), Phoebe sp, Lt hoa (Chukrasia tabularis), To vng (Drypetes perreticulata), An phong (Alphonsea sp.), Mi liu (Miliuisa balansae), Cm ru (Glycosmis sp.), Th (Diospyros sp.), Bng bng (Arenga pinnata), Mu ch (Knema sp.), Cch hoa (Cleistanthus sumatranus), Nhc (Polyalth-ia sp.), Bnh linh (Vitex sp.), Gi (Aglaia gigantea), Du da xoan (Spondias lakonensis), v.v. c) Rng kn thng xanh nh ni vi (Evergreen forests on top of limstones) Cu trc rng n gin thng ch 1 n 2 tng gm nhng cy cao t 8 - 15m nh: Chn chim (Schefflera spp.), Sm (Memecylon spp.), Sn t (Sinosideroxylon sp.), Bng mc (Boniodendron sp.), B tt (Pistasia cucphuongensis.), Cnh kin (Mallotus philippensis). Thc vt tng thp l nhng loi cy bi nh Mua (Melastoma spp.), Trm (Syzygium spp.) v lp thm ti nh Rng cnh bn (Dryopteris spp.), Rng c l (Colysis cucphuongensis), Rng ym dc (Tectaria spp.), Quyn b (Selaginella spp.), Ring (Alpinia spp), Thu hi ng (Begonia spp), Bng nc (Impatiens spp.), Thuc bng (Kalanchoe sp.) vi cc loi cy thuc h Phong lan (Orchidaceae), Tm gi (Lo-ranthus spp.), dy leo nh Vng (Jasminum sp.), Mnh bt (Coccinia grandis), i hi (Hodgsonia macrocarpa), v.v.

3.2. Rng ni vi ai cao 700 - 1.000 m (Forests on limstones with elevation of 700 1000m)

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

a) Rng cy l rng thng xanh thung lng v chn ni vi (Evergreen broad leaved forests on valley and foots of limestone):

Ph bin c cc loi thuc Gi (Aglaia sp.), Ch nu (Dipterocarpus retusus), Ch ch (Shorea chinensis), Tu rui (Vatica diospyroides), Gi (Quercus spp.), Si (Lith-


ocarpus spp.), Mc lan (Michelia sp.), M (Manglietia sp.) v Long no nh Litsea spp, Cryptoccarya spp., Machilus spp. tng 1 v cc loi: Th (Dipspyros spp), Cho (Engelhardtia sp.), Nhi (Bischofia javanica), C mui (Cipadessa baccifera), Nh ni (Hydnocarpus clemensorum), Lng mang (Pterospermum sp.), Su (Celtis cinamomea), Sn tr (Eriobotrya poilanei), Re (Cinnamomum bonii), Xoan hi (Toona sinensis), Lt ni (Koelreuteria sp.) tng 2 v th (Diospyros spp.), ngt (Gironniera subaequalis), nhc (Polyalthia sp), mc mt (Clausena spp.) tng 3.

b) Rng cy l rng thng xanh sn ni vi:

Ph bin loi nghin (Burretiodendron), nh ln vi ng knh 70 - 80 cm, Trai (Garcinia sp.), inh (Marchantia sp.), Lng mang (Pterospermum heterophyllum), Trm (Syzygium spp), Th (Diospyros sp.), Kho (Phoebe sp), Nhc (Polyalthia sp), Thi ba (Al-angium chinense).

c) Rng hn giao cy l rng, l kim nh ni vi (Mixed broad and needle leave forests on top of limestone)

Ch yu l cc loi cy a, Sanh (Ficus sp.), Trm (Syzygium spp), Chn chim vi (Schefflera octophylla), H o ni (Juglans sp.), Du vi (Ulmus sp.), Pt t (Pittospo-rum sp.). Chn chim h long (Schefflera halongensis). Ngoi cc loi cy l rng nh trn, cn c cc loi nh: cc loi Tu (Cycas spp.), Hong n (Cupressus torulosa), Hong n gi (Dacrydium elatum), Kim giao (Nageia fleuryi), Thng tre l ngn (Podocarpus pilgeri), Thng P C (Pinus kwangtungensis), Du sam vi (Ketelee-ria davidiana var. davaniana), Sam bng sc nu (Amentotaxus hatuyenensis), Sam bng sc trng (Amentotaxus yunnanensis), Thng (Taxus chinensis), Sam kim h (Pseudotsuga chinensis), Bch vng (Xanthocyparis vietnamensis). Tng thp ch yu l cc loi cy nh Thanh hng (Pistacia weimanifolia), Cng (Calophyllum bonii), Mc mt (Clausena indica), Huyt gic (Dracaena cambodiana), Han (Laportea sp.), Thu hi ng (Begonia sp.), M h (Mahonia nepalensis), C l tre (Setaria palmifolia), v.v.

d) Rng ln cy l rng nh ni vi (Short broadleave forest on top of limestone)

Cu trc rng ch c mt tng vi nhng cy g nh chiu cao khong 6-10 m. Cc loi c trng nh: Tu (Cycas spp.), Thit sam gi (Pseudotsuga chinensis), Thit sam gi l ngn (P. brevifolia ), Thit sam ng bc (Tsuga chinensis), Hi ni (Illicium grif-fithii), cc loi Ng gia b (Schefflera spp), D (Quercus spp., Lithocarpus spp.), Ch ni (Ternstroemia japonica), Pistacia weimanifolia), quyn (Ericaceae) nh: Rhododen-dron spp., Vaccinium dunalianum v cc loi Re (Cinnamomum sp.), Li ni (Jas-minum lanceolarium), Cng (Tirpitrzia sinensis), v.v.


4. H sinh thi rng l kim t nhin (Natural needle leave forests)

H sinh thi rng l kim gm 2 dng: h sinh thi rng l kim nhit i ni thp phn b ch yu vng ni nh Yn Chu, Mc Chu (Sn La), Ngh An, H Giang, Lt (Lm ng), v.v, v h sinh thi rng l kim n i ni cao trung bnh phn b ch yu Sa Pa (Lo Cai), Tun Gio (Lai Chu) H Giang, Ty Cn Lnh (Cao Bng), Ch Yang Sinh (Nam Trung B), Lm ng, v.v. Cc h sinh thi rng l kim t nhin gm:

a) H sinh thi rng l kim nhit i ni thp (Lowland sub-tropical needle leave forest)

min Nam, tng cy g ch yu Thng nha (Pinus merkusii), Thng ba l (Pinus kesiya) mc ln vi Tr beng (Dipterocarpus obtusifolius). min Bc, in hnh l cy Du sam (Keteleeria davidiana), Thng nha (Pinus merkusii). C 2 kiu ph thuc h sinh thi ny:

l Kiu ph min thn thuc vi khu h thc vt n - Myanma: min Nam c trng rng thng nha (Pinus merkusii) t nhin vi cc loi mc xen ln nh Du tr beng (Dipterocarpus obtusifolius), D (Lithocarpus harman-dii), Gii b (Michelia bailonii), v.v. Tng cy bi thp thng c loi Chua nem (Vaccinium chevalierri) v Vi thuc (Schima crenata). Tng thm ti gm c c Gut (Dicranopteris linearis), Quyt (Nephrolepis hirsuta). v.v.

l min Bc, ti Qung Yn (Qung Ninh), c cc loi mc xen nh Lim xanh (Erythrophoeum fordii Olive), D gai (Castanopsis tribuloides), Re (Cinnamo-mun sp). Tng cy bi gm c chua nem (Vaccinium chevalierri), Hoc quang (Wendlandtis glabrata)

l Kiu ph min thc vt thn thuc vi khu h thc vt Himalaya - Vn Nam - Qu Chu: c trng l rng Thng ba l (Pinus kesiya) mc xen ln vi cc loi d nh Quercus helferiana, Lithocarpus dealbata, Lithocarpus pynostachya, v.v. Ngoi ra cn c cc loi trong h quyn (Ericaceae).

cao nguyn Mc Chu (Sn La), Thun Chu (Lai Chu), v.v, c Du sam (Keteleeria davidiana) chim u th tng trn vi cc loi d rng l nh Quercus griffthii, Quer-cus serrata, Quercus acutissima v.vv cc loi cy trong h Re (Lauraceae).

b) H sinh thi rng l kim n i ni cao trung bnh (Temperate needle leave forests on medium mountain):

Trong vnh ai ny, rng cy l kim mc thun loi nh P mu (Fokienia hodginsii), Sa mu (Cunninghamia lanceolata), Thng nng (Podocarpus imbricatus). Mc xen vi P mu cn c Thng l dp (Ducampopimus krempfii ), Thng nm l Lt (Pinus


dalatnensis). Ngoi ra, vnh ai n i ni cao thuc dy ni Phan Xi Png trn cao 2.400 - 2.900 m cn c Thit sam (Tsuga yunnanensis ), cao trn 2,600 m (Abies pindrow ), v.v.

Kiu ph cho h sinh thi ny l kiu ph min thc vt thn thuc vi khu h thc vt Bc Vit Nam - Nam Trung Hoa. Kiu ph ny c pht hin Mng Phng, cao 1335 m so vi mc nc bin vi 3 tng chnh u th l T hp (Calocedrus macrolepis) cao n 35m, mc hn loi vi Actinodaphne sinensis, Phoebe sp, Litsea baviensis v.v thuc h Re (Lauraceae), v D gai (Castanopsis hickelii) thuc h D (Fagaceae). Tng A2 cao t 10 - 20 m bao gm mt s loi cy thuc h Re (Lau-raceae), h B hn (Sapindaceae), h Mu ch (Myristicaceae) v h Du (Ulmaceae). Tng B gm mt s loi cy Blastus sp, Cau rng (Pinanga baviensis ), loi Lasianthus sp, dng x thn g (Gymnosphoera podophylla ), St (Arundinaria sp).

5. H sinh thi rng tha cy h du (Dry dipterocarp forest) Rng khp phn b tp trung tnh k Lk, Gia Lai. Ngoi ra cn c Di Linh (Lm ng) v nhng m rng khp nh phn b Ninh Thun, Bnh Thun, Sng Be, Ty Ninh. V v , rng khp phn b t v 14oB (Gia Lai) n v 11o B (Ty Ninh). V cao so vi mc nc bin, rng khp phn b tp trung cao t 400 - 800 m. Khu h thc vt rng khp c lin quan n khu h thc vt Malaixia - Innxia vi t thnh loi cy h Du (Dipterocarpaceae) chim u th. Khu h thc vt rng khp bao gm 309 loi cy thuc 204 chi, 68 h, trong c hn 90 loi cy g vi 54 loi cy g ln, g trung bnh.

Ngoi nhng loi cy h Du chim u th cn c: Cm xe (Xylia xylocarpa) thuc h Trinh n (Mimosaceae), Lng bng (Dilleniahe terosepala) thuc h Dilleniaceae, n (Vitex pendencularia) thuc h Verbenaceae, M ca (Buchanania arborescens) thuc h Anacardiaceae v.v. iu kin lp a tt, c th xut hin mt s loi cy c gi tr nh Ging hng (Pterocarpus macrocarpus), Cm lai (Dalbergia bariensis), v.v. Di y gii thiu 4 u hp cy h du ph bin.

l u hp cm lin (Shorea siamensis): Cm lin mc hn giao vi hai loi cy ph bin l Du ng (Dipterocarpus tuberculatus) v Ging hng (Pterocarpus macrocarpus). Ngoi ra cn c cc loi cy C cht (Shorea obtusa), Go (Nau-clea spp.), Sng l (Lagestroemia spp.), v.v.

lu hp c cht (Shorea obtusa): C cht chim u th n 50% c th. Ngoi ra cn mc hn giao vi Cm lin (Shorea siamensis), Du tr beng (Dipterocar-pus obtusifolius), v.v.


l u hp Du ng (Dipterocarpus tuberculatus): Ba loi cy ph bin hn giao vi du ng l chiu liu lng, Cm lin lin (Shorea siamensis), C cht (Shorea ob-tusa), trong Du ng v Cm lin ng gp phn ln vo tr lng rng.

lu hp du tr beng (Dipterocarpus obtusifolius): u hp ny phn b tp trung cao so vi mc nc bin t 600 - 900 m thuc cc tnh k Lk, Gia Lai, Lm ng.

6. H sinh thi rng ngp mn (Mangrove forests)

H sinh thi rng ngp mn phn b dc b bin Vit Nam thuc 28 tnh v thnh ph. Phan Nguyn Hng (1999) chia vng phn b rng ngp mn Vit Nam thnh 4 khu vc vi 12 tiu khu v xc nh iu kin sinh thi cho tng tiu khu: khu vc I - ven bin ng Bc; khu vc II - ven bin ng bng Bc B; khu vc III - ven bin Trung B t mi Lch Trng n mi Vng Tu; v khu vc IV - ven bin t Vng Tu n n mi Ni, H Tin (ven bin pha ty bn o C Mau).Cc i din cho h sinh thi ny ch yu cc cy a mn: c (Rhizophora apicu-lata), c i (R. Mucronata), Vt khang (Brugyeria parviflora), Vt tr (B. Gymnorhi-za), Trang (Kandelia ovata) thuc h c (Rhizophoraceae); Mm bin (Avicennia marina). Mm trng (A. Alba), Mm en (A. Oficinalis) thuc h mm (Avicenniaceae); Bn chua (Sonneratia alba), Bn s (S. Caseolaris) thuc h Bn (Sonneratiaceae); Ch l (Phoenix paludosa) thuc h Da (Palmae).

7. H sinh thi rng trm (Melaleuca cajuputi)

H sinh thi ny phn b tp trung 7 tnh ng bng sng Cu Long, hnh thnh nn ba vng sau y: I) vng ng Thp Mi thuc ba tnh Long An, Tin Giang v ng Thp ; II) vng T Gic Long Xuyn thuc hai tnh An Giang v Kin Giang ; v III) vng U Minh Thng v U Minh H thuc tnh C Mau v Kin Giang.

Trc y, loi trm c xc nh tn khoa hc l Melaleuca leucodendron. T nm 1993, tn khoa hc loi trm c xc nh li l Melaleuca cajuputi (Scott Poyn-ton, 1993). Loi trm Vit Nam c t nht 4 chng (variete) l trm c, trm gi, trm bi v trm bng. Trm c v trm gi phn b t nhin trn t phn ng bng sng Cu Long. Trm bi v trm bng phn b t nhin Qung Bnh, Qung Tr v Tha Thin Hu. Do h sinh thi rng trm hnh thnh trong iu kin mi trng c bit l ng phn, ch c mt s loi cy thch nghi tn ti c nn cu trc rng n gin hn nhiu so vi h sinh thi rng hn loi thng xanh.


8. H sinh thi rng tre na (Bamboo forest.)

Tre na l tn gi chung cho cc loi thc vt thuc phn h Tre ( Bambusoidae), h Ho tho (Gramineae hay Poaceae). Tre na phn b rng t vng nhit i, nhit i n n i, t 51o v bc n 47o v nam. Trn th gii c khong 1.300 loi thuc hn 70 chi, phn b 3 vng chnh: Chu Thi Bnh Dng, Chu M v Chu Phi, trong vng Chu Thi Bnh Dng l trung tm phn b tre na chim khong 80% tng s loi v din tch ton th gii (Lin, 2000).

Vit Nam l mt trong nhng vng trung tm phn b tre na trn th gii. Tre na Vit Nam c 133 loi thuc 24 chi. Cc HSTR tre na Vit Nam gm cc dng nh sau:

l H sinh thi rng lung (Dendrocalamus barbatus) Lung c tn khoa hc l Dendrocalamus barbatus Hsueh et Li, trc y

c gi l Dendrocalamus membranaceus. Lung phn b nhiu cc tnh nh Thanh Ho, Ngh An, H Tnh, Sn La, v.v, nhng tp trung nhiu nht Thanh Ho. Lung mc t nhin mi c ghi nhn c dc sng M, Sn La, cn li hu ht l rng lung trng.

l H sinh thi rng vu (Acidosasa v Indosasa) Vu l tn gi chung cho mt sloi tre mc tn thuc chi Acidosasa v Indosasa, bao gm mt s loi chnh nh: vu ng (Indosasa sp.), vu l nh (Indosasa amabilis), vu ngt (Aci-dosasa sp.), vu xanh (Acidosasa sp.), v.v. Trong cc loi vu nc ta th vu ng c ngha ln nht, do din tch tng i rng, phn b kh tp trung, kch thc ln v gi tr kinh t cao. Do , trong phn ny s gii thiu v loi vu ng. Vu phn b nhiu cc tnh Lo Cai, Yn Bi, H Giang, Tuyn Quang, Bc Kn, Ph Th, Thi Nguyn, Lng Sn, Qung Ninh, Sn La, Ho Bnh, Thanh Ho, v.v.

l H sinh thi rng na (Neohouzeaua forest) Na l tn gi chung cho mt s loi mc cm thuc chi Schizostachyum, trc

y c xp vo chi Neohouzeaua, trong loi na l to (Schizostachyum funghomii) v na l nh (Schizostachyum pseudolima) c phn b rng, din tch ln v c nhiu ngha kinh t. Na l nh phn b rng hu khp c nc, nhng tp trung nhiu vng Trung tm Bc B v Bc Trung B.

l H sinh thi rng l (Bambusa balcoa) L c nhiu tn gi khc nhau nhng hin nay thng nht nh sau (Bam-

busa balcoa Roxb.). L phn b kh rng Nam Trung B, Ty Nguyn v ng Nam b, nhng tp trung nhiu nht vng ng Nam B, nht l tnh Bnh Phc.


3.3 Cc h thng phn loi rng Na th k va qua trn cc c s khoa hc khc nhau, mc tiu s dng khc nhau, rng Vit Nam c phn loi theo cc phng php lun cng khc nhau, v cho cc kt qu rt phong ph v c p dng trong thc tin kinh doanh rng, quy hoch-qun l rng trong c nc. Cc c s l thuyt v phng php lun cng c tham kho, nghin cu, ging dy t c cng cc mc khc nhau.

H thng phn loi da trn c s h sinh thi, vi 5 nhn t chnh chi phi vic pht sinh, pht trin ca rng nhit i Vit Nam t ting vang trong thp k 60, nhng 14 kiu rng, ngoi gi tr l thuyt, li khng c p dng ng k. Trong khi h thng phn chia hin trng rng thnh 4 loi ca nc c chuyn giao vo Vit Nam cui thp k 50 khng km theo phng php lun no, th li c s dng rng ri, lin tc, do tnh n gin, tnh bao qut thc t, li gn vi phn cp tr lng g, c nhiu ln b sung ci tin cho n ngy nay. Trong bo co ny, 5 h thng phn loi rng chnh c trnh by nh sau.

3.3.1 H thng phn loi rng theo hin trng

Nm 1959, h thng phn loi rng ca Cng ha dn ch c do Loeschau chuyn giao vo Vit nam gm 4 loi rng:

Loi IV: Rng nguyn sinh hoc b tc ng cha ng k, gm cc h sinh thi t nhin, c kt cu c coi l sn phm ca cc nhn t sinh thi pht sinh, c tr lng, sn lng v chng loi lm sn cao t nhin, m khng theo phng hng chn lc ca nn kinh t. Rng loi IV gm IVa v IVb biu th rng nguyn sinh v rng trng n tui thnh thc. Loi III: Rng t nhin b tc ng cc mc khc nhau, v th chng ang trong giai on phn ha (hoc ang phc hi, hoc ang thoi ha). Ty theo mc tc ng nhiu hay t, rng loi III c chia nh thnh 3 mc :

lIIIa: Mc tc ng ln, rng b thoi ha, khng cn kt cu tng tn bnh thng, sn lng, tr lng lm sn b suy thoi nghim trng cc dng rt nghim trng (IIIa1), dng th 2 b tc ng mnh, nhng rng cn kh nng phc hi t nhin (IIIa2). Sau ny trong sn xut quy nh thm loi IIIa3 trn mc ca IIIa2.

l IIIb: Mc tc ng trung bnh thng l khai thc rng thnh thc (loi IV), hoc rng sau khai thc (dng IIIa) phc hi tun th cc quy trnh quy phm nn v cu trc, v sn lng p ng cc cng khai thc cho phep.


l IIIc: Loi ny biu th s tc ng t hoc nh ca con ngi vo rng loi IV hoc rng loi III phc hi y . Loi rng IIIc t c phn hng v thng dng so vi IIIa v IIIb.

Loi II: L rng non/rng so, bao gm:

l IIa rng non phc hi t nhin sau khi mt rng do chy hoc do lm nng ry.

l IIb l rng non/rng so nhn to khep tn, tr lng g cha ng k.

Loi I: t trng i ni trc, cha h c rng, hoc mt rng do khai thc qu mc, la rng hoc cc nguyn nhn khc. Tuy nhin tr cc bi ct trng, trn t trng, i ni trc bao gi cng tn ti thm c, cy bi, cc cy g ti sinh t ht hoc chi c chiu cao bng chiu cao thm c hoc chiu cao thm cy bi. Trong s dng thc tin, Vin TQHR b sung thm 3 loi ph, v c s dng rng ri cho n ngy nay:

l Ia: t trng trc: Thm c hoc cy bi tha tht, che ph mt t di 30%.

l Ib: t trng c che ph bi thm c hoc thm cy bi hoc hn hp gia chng, c che ph mt t ln hn 30%

l Ic: t trng i trc ca dng Ib nhng c nhiu cy g non ti sinh. Loi Ic mi c quy nh thm khi chng trnh 327 (1992-1997) c hng dn gii php khoanh nui phc hi hoc xc tin ti sinh t nhin ti nhng lp a c cy g ti sinh c trin vng tr thnh rng t nhin loi IIa.

H thng phn loi ny c s dng rng ri trong sn xut lm nghip t gia th k XX cho ti ngy nay v c ngnh lm nghip b sung v hon thin dn theo nhu cu pht trin ca ngnh. Ln b sung mi nht l nh ngha li rng theo Thng t 34/2009/BNN nm 2009. Tuy nhin h thng phn loi ny ch nhm mc ch phc v vic phn loi rng theo tr lng hin ti kinh doanh rng, khai thc g, m khng da vo c s sinh thi, pht sinh, pht trin, hoc cu trc t thnh ca cc thm thc vt.

3.3.2 Phn loi thm thc vt rng theo cc nhn t sinh thi pht sinh

Tip cn hc thuyt sinh-a-qun lc (biogeoceology) ca vin s V.N. Sucasov (1957), v l thuyt h sinh thi (ecosystem) ca A.G.Tansley (1930), Thi Vn Trng (1963, 1999) cn c vo quan im sinh thi pht sinh qun th thc vt phn


loi thm thc vt rng Vit Nam. T tng hc thut ca quan im ny l trong mt mi trng sinh thi c th ch c th xut hin mt kiu thm thc vt nguyn sinh nht nh. Trong mi trng sinh thi , c 5 nhm nhn t sinh thi pht sinh nh hng quyt nh n t thnh loi cy rng, hnh thi, cu trc v hnh thnh nn nhng kiu thm thc vt rng tng ng. Cn c vo c s l lun trn, Thi Vn Trng dng 5 nhn t (kh hu, a hnh, th nhng, h thc vt, nhn tc) phn loi thm thc vt rng Vit Nam thnh 14 kiu rng c trn t lm nghip nh sau:

Cc kiu rng kn vng thp

I. Kiu rng kn thng xanh, ma m nhit iII. Kiu rng kn na rng l, m nhit iIII. Kiu rng kn rng l, hi m nhit iIV. Kiu rng kn l cng, hi kh nhit i

Cc kiu rng tha

V. Kiu rng tha cy l rng, hi kh nhit iVI. Kiu rng tha cy l kim, hi kh nhit iVII. 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 iIX. Kiu trung bi gai, hn nhit i

Cc kiu rng kn vng cao

X. Kiu rng kn thng xanh, ma m nhit i ni thpXI. Kiu rng kn hn hp cy l rng l kim, m nhit i ni thpXII. 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 thnh thc vt), kiu ph th nhng (ph thuc vo iu kin t), kiu ph nhn tc (ph thuc vo tc ng ca con ngi) v trong mi kiu ph tu theo u


th ca loi cy m hnh thnh nn nhng phc hp, u hp v qun hp t nhin khc nhau. Nh vy, bc tranh h sinh thi rng nc ta rt a dng v phong ph thng qua h thng phn loi ca Thi Vn Trng.

3.3.3 Phn loi cc h sinh thi theo ai cao v iu kin sinh thi

Trn Ng Phng (1970) xut bng phn loi rng min Bc Vit Nam theo cc yu t t ai, kh hu, cao, v nhn t c trng ca rng phn loi rng min Bc thnh 3 ai rng. Trong mi ai, cha ng mt hoc mt s kiu rng c bn:

A. ai rng nhit i ma ma:

l Kiu rng nhit i l rng thng xanh ngp mn

l Kiu rng nhit i ma ma l rng thng xanh

l Kiu rng nhit i m l rng thng xanh

l Kiu rng nhit i l rng thung lng

l Kiu rng nhit i l rng thng xanh ni vi

B. ai rng nhit i ma ma:

l Kiu rng nhit i l rng thng xanh

l Kiu rng nhit i l kim trn ni vi

l 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 (Cunninghamia lanceo-lata), quyn (Rhododendron simsii).

H phn loi ny l thnh qu bc u nghin cu lm sinh hc rng min Bc Vit Nam, bo co ti Hi ngh lm nghip Bc Kinh 1967, xut bn 1970.

3.3.4 Thang phn loi rng ca UNESCO

UNESCO (1973) phn loi thm rng ni chung thnh 4 lp qun h. Ti Vit Nam ch c 2 lp l: lp qun h rng rm v lp qun h rng tha.


Mi lp qun h li chia thnh cc phn lp, mi phn lp li chia thnh cc nhm qun h v sau mi n n v qun h. Mi qun h li c chia thnh cc phn qun h v di l qun hp. Cn c vo nguyn tc phn loi nh trn, thm thc vt rng Vit Nam c phn loi kh phc tp nh sau:

I. Lp qun h rng rm gm 3 phn lp chnh l: rng thng xanh, rng rng l 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:

l Rng t thp

l Rng ni thp

l Rng ni va

l Rng ni cao

l Rng ni vi thp

l Rng ni vi trung bnh

l Rng bi ct ven bin

l Rng trn t ph sa

l Rng ngp nc

l Rng s vt

l Rng thng trn ni thp

l Rng tre na trn ni thp

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

l Rng na rng l nhit i trn t thp

l Rng na rng l nhit i trn ni thp

l Rng na rng l nhit i trn ni vi

l Rng na rng l nhit i trn ni cao trung bnh


2. Phn lp qun h rng rng l nhit i

l 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:

l Rng gai na rng l

l Rng gai rng l

II. Lp qun h: 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:

l Rng trn t thp

l Rng trn ni thp

b) Nhm qun h rng l kim

2. 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:

l Rng gai na rng l

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, vi 5 nhn t sinh thi, nhng n nay vn ch l cc cng trnh l thuyt, cha c s dng nhiu, hoc mi c s dng tng phn trong thc tin sn xut.

3.3.5 Phn loi HSTR t nhin theo Cm nang ngnh Lm nghip Trn c s 5 nhm nhn t sinh thi m t trn, Phng Ngc Lan v cs (2006) h thng li, sp xp li thnh 8 h sinh thi ch yu theo iu kin sinh thi v c im cu trc ni ti mi kiu. Mi h c coi l mt kiu rng chnh, mi kiu rng cn c cc kiu ph min v cc u hp ch th. Mi h sinh thi c m t k cc c tnh: Phn b, sinh thi v cu trc. Cc h sinh thi rng t nhin l:

l Rng kn thng xanh ma m nhit i

l Rng kn na rng l m nhit i

l Rng l rng thng xanh trn ni vi

l Rng l kim t nhin

l Rng tha cy h du

l Rng ngp mn

l Rng trm

l Rng tre na

Cch phn chia cc h sinh thi t nhin ny phn no ging nh phn loi hin trng, nhng c gii thch k c im kt cu ni ti khu rng v hon cnh pht sinh pht trin ca chng. y cng chnh l c s cng trnh ny tip cn.

3.3.6 Cc kiu rng s dng trong phn vng STLN

Cc HSTR nguyn sinh l bng chng quan trng chng minh cc iu kin sinh thi hnh thnh v m bo s tn ti lu i ca chng trn cc vng lnh th Vit Nam. Song, trong qu trnh pht trin lu i, chnh cc nhn t sinh thi cng thay i hoc t t, hoc t xut, c bit l nhn t con ngi (nhn tc) li cho th h chng ta mt bc khm phong ph nhng qu phc tp cc loi rng, a phn l th sinh hoc nhn to, m va c trnh by tm tt c phng php lun, c hiu qu p dng ca tng h thng c c s chn lc cc kiu rng chnh (tng ng h sinh thi) trong phn vng lnh th.Trong 10 kiu rng chn lc ln ny bao gm y cc kiu rng t nhin,


ca h thng phn loi theo Cm nang ngnh Lm nghip, ng thi b sung y cc kiu rng th sinh ang trong qu trnh din th, v cng a vo c cc h rng trng, cc loi thm thc vt cha thnh rng (trng, trung theo Thi Vn Trng, 1963; Ib, Ic theo phn loi hin trng b sung) bao qut mi hnh thi thm thc vt rng hin c.

Bng 3 lit k tn 10 kiu rng chnh v k hiu (m s) mi kiu rng, vi 4 kiu ph cho khi rng t nhin hn loi.

Bng 3. Cc kiu rng chnh Vit Nam Kiu rng

I. Rng kn, hn loi, l rng thng xanh ma m. Cc kiu ph gm:

- I1: vng thp di 700 m min Bc v di 1000 m min Nam

- I2: vng thp Nam B, u hp h Du

- I3: i (di 300m), ni thp (300-700m), trung bnh (700-1500m) min Bc; ni

thp (500 1000m); ni trung bnh (1000-2000m) min Nam (theo cm nang)

- I4: Ni cao > 1500m min Bc, >2000m min Nam

II Rng hn loi na rng l

III Rng hn loi trn ni vi

IV Rng l kim, hn loi l rng l kim

V Rng tha, kh l rng rng l theo ma, u th h Du (khp)

VI Rng ngp mn ven bin

VII Rng ng phn (rng Trm)

VIII Rng tre na v hn loi cy g + tre na

IX Rng trng cc loi

K hiu


0404


V l thuyt, tiu ch quan trng nht phn vng STLN l s phn b t nhin ca cc HST (hay kiu rng trn phm vi n v phn chia, v vy nu c HST nguyn sinh, m cao nh gi l climax no , th cc nhn t sinh thi ch cn l h thng l thuyt to ra hon cnh mi trng hnh thnh nn HST tham kho. Song trong a s trng hp ti cp phn v thp, nh tiu vng, khi HST nguyn sinh khng cn na th cn ti cc tiu ch to ra mi trng pht sinh v pht trin ca HST theo nguyn l hon cnh sinh thi no th to ra kiu rng . y chnh l c s d bo hoc ti y tng tn ti HST nguyn sinh ny, hoc din th th sinh cc kiu rng hin ti ang theo xu hng phc hi li nguyn mu HST nguyn sinh .

Trong phm vi cng trnh chuyn su v sinh thi rng, khi xem xet 5 nhn t sinh thi pht sinh th nhn t th 5 nhn tc l ch con ngi, thn thin hay tn ph thin nhin, n tng hc c nhiu bi hc v quyt nh hng i cho tng lai. Nhn t khu h thc vt l chn l thc tin xc nhn tnh ng n ca s phn b t nhin cc kiu rng nguyn sinh, nhng nay b thay bng cc kiu trung gian, hoc ang suy thoi, hoc ang phc hi, v phi c coi l cc i tng hin thc khch quan ca l thuyt phn vng.

C s khoa hc xy dng tiu ch phn vng STLN04


Ba tiu ch sinh thi cn li, gi tt l kh hu, a hnh, th nhng l ba h thng quan trng nht to ra mi trng pht sinh ca cc kiu rng m ta phn vng, song trong tng phn v (cp phn vng), tng trng hp c th nhn t no l ch o, nhn t no t gy tc ng li l do tnh quy lut ca cc kt qu nghin cu, hoc kinh nghim chuyn gia ch ra. V d cc ch tiu kh hu khc nhau ro rt v chi phi ro trong phm vi cc phn v ln nh min, vng, trong khi cc ch tiu v t li nh hng ro rt trong cc phn v nh nh vng, tiu vng hoc nh hn na.

Ba lnh vc ny l 3 ngnh chuyn mn c lp, tng c nghin cu y , c phn vng t nhin trn lnh th Vit Nam, hoc phn vng ng dng theo tng lnh vc cho cc ngnh kinh t lin quan khc (m t chi tit trong mc 2.1 v phn vng lnh th, hoc nh ngnh Kh hu ngoi phn vng kh hu t nhin, cn c phn vng kh hu ng dng cho nng nghip, xy dng ti tit mc 4.1. Nh vy, so vi phn vng STLN, cc ngnh chuyn mn ny tin mt bc xa hn, v chng ti ghi nhn trong cc phn di y l tm tt cc thnh tu chnh ca mi lnh vc v phn vng lnh th.

Trong s lin quan nh mt nhn t sinh thi ca s hnh thnh v pht trin cc HSTR, mi nhn t kin ngh cc tiu ch v ch tiu (C&I) h tr cho ngnh lm nghip la chn, cc khuyn ngh cho mi phn v khi phn vng STLN.

4.1 Kh hu - thy vn

4.1.1 Kinh nghim quc t

Trn th gii c nhiu h thng, nhiu phng php ph hp cho cc iu kin khc nhau, thng phn loi kh hu theo cc h thng sau y:

lPhn loi ca Koppen (1918-1936). Trn c s kt hp ch s nhit , lng ma. Sau ny Trewartha b sung kt hp thnh h thng Koppen - Trewartha, to ra h thng phn loi kh hu th gii 7 nhm t A n H, t vng qu nng n vng cc lnh, c trng bi ch s : s thng c nhit trung bnh bng hoc trn 18oc, t nhm C th so vi nhit trn 10oc.

l H Thornthwaite: L h thng Koppen c kt hp gim st s bc thot hi nc trong mt khu vc. N cng s dng ch s m v kh cn bit lng m c thm thc vt s dng.

l Phn loi ca Holdridge (1947, 1967). y l h thng sinh kh hu phn loi t ai v lp bn , p dng trn ton cu. H thng c tch hp t 3 ch s l: Nhit sinh hc, v , ai cao.


lNguyn tc phn vng sinh thi ca FAO (Zhu, 1997; Preto, 1998). y l h thng phn loi kh hu c yu t sinh thi rng.

4.1.2 Phn vng lnh th theo kh hu

Vit Nam nghin cu vic phn vng lnh th theo chuyn ngnh kh hu gi tn l Phn vng kh hu min Bc Vit Nam (1964), Phn vng kh hu t nhin (Nguyn Hu Ti, 1985, Nguyn c Ng & Nguyn Trng Hiu, 2004). H thng ny ang c s dng rng ri trong c nc, vi 7 vng kh hu l: ng Bc, Ty Bc, ng Bng Bc B, Bc Trung B, Duyn hi Nam Trung B, Ty Nguyn v Nam B.Nhiu cng trnh nghin cu v Phn vng kh hu cho nhiu chuyn ngnh khc nh Phn vng kh hu xy dng (Trn Vit Lin, 1984, 2002); Phn vng kh hu nng nghip (L Quang Hunh, 1985)

4.1.3 Phn v Cc s phn vng kh hu t nhin Vit Nam ca Nguyn Hu Ti (1985), Nguyn c Ng & Nguyn Trng Hiu (2004) c mt h thng ch tiu kh tng ng, c th m t tm tt nh sau:

l Min kh hu: l cp phn v dng th hin s khc bit v kh hu c lin quan n nh hng ca gi ma ma ng trong s h thp ca nhit ma ng dn n hnh thnh 2 ma nng lnh c vai tr quyt nh.

l Vng kh hu: l cp c s ca s , th hin s khc nhau v kh hu c lin quan n nh hng ca gi ma ma h dn n s khc nhau v ma ma cc vng.

l Tiu vng kh hu: l cp phn v b sung nhm th hin chi tit hn s phn ha kh hu trong mi vng, c biu hin qua nhiu c trng kh hu khc nhau.

4.1.4 Tiu ch v cc khuyn ngh phn vng STLN

l Min kh hu:

Ch tiu chnh phn vng min kh hu l bin nm ca nhit (toc). Ch s s dng phn chia 2 min l (t=8oc). Ngoi ra cn 2 ch tiu kt hp l nhit trung bnh thng thp nht (Tnm = 20

oc), tng nhit nm (Q = 9000oc) v tng s gi nng nm (S=2000 gi).

l Vng kh hu: Phn chia vng kh hu s dng 2 tiu ch l: bin nhit nm v bin nhit ngy; v nhit trung bnh thng thp nht. C 8 vng kh hu trn c nc v mi vng c ch s ring cho phn vng.


l Tiu vng kh hu:Tiu ch c s dng gm: Lng ma trung bnh nm, ma, nhit trung bnh nm v cc tr v ch s m. Cc thng s ny c tnh ton t s liu cc trm quan trc.l Khuyn ngh cho phn vng STLN:

S liu l c s quan trng th nghim m hnh, xy dng h thng ch tiu v nh cc ng ranh gii. Vi t l kh ln 1/250.000, s liu s dng buc phi l s liu li vi mt dy (vi phn gii c 1-5km). Vic x l, hiu chnh theo s liu quan trc c vai tr c bit quan trng.

Phng php phn vng hng chnh vo cc phng php truyn thng thuc nhm cc phng php a l kh hu nh phn tch trn. H thng phn v s theo quy hoch chung ca d n vi 2 cp c bn l vng v tiu vng. Cc phng php v h thng ch tiu ca cc s phn loi kh hu th gii ca Koppen, Kppen-Trewartha, Holdridge; cc bn phn vng kh hu Vit Nam cng vi h thng phn v v ch tiu phn vng l ti liu tham kho quan trng. Vic nghin cu cc ch tiu kh hu sinh thi cng nh vic t hp cc c trng kh hu c bn to thnh cc phc hp phn nh c mi quan h gia kh hu vi sinh trng, nng sut cy rng s l hng pht trin h thng phn v v ch tiu phn vng.

Nh xut phn vng kh hu cho lm nghip gm 3 phn v l min, vng v tiu vng. Cc tiu ch v ch s cho mi phn v c xut trong bng 4. Cch phn vng ny cho thy kh hu nh hng ln ti phn chia Min v Vng nhng kh hu nh hng t ti phn chia tiu vng. Di y l cc tiu ch xut cho phn vng STLN (Trn Vit Lin v cs, 2011).Thc ra, nh hng ca cc nhn t kh hu n cc phn v ln ca phn vng STLN l rt mnh, cho n cp Tiu vng kh xc nh ch kh hu c th cho tiu vng, do thng m t c im trung bnh ca cc yu t ph bin nht nh nhit , lng ma.

4.2 a hnh - a mo

4.2.1 Kinh nghim quc t v Vit Nam

Nhm nhn t a cht/a mo l nhng nhn t c s hnh thnh lu di trong lch s kin to ca Tri t, quyt nh s hnh thnh cc i dng v cc lc a, hnh thi v thnh phn vt cht ca v Tri t. Tuy nhm nhn t a cht/a mo khng nh hng trc tip n thnh phn cc kiu thm thc vt, nhng chng li l nhng nhn t c tc dng chi phi nh hng ca nhng nhn t khc nh kh hu, thu vn, m, th nhng n cc h sinh thi lm nghip. Nhm nhn t


Cp phn v Tiu ch

Min - Bin nhit trung bnh nm (T) l 8oC- Tng nhit nm l 9000oC- Tng s gi nng l 2000 gi

Vng - Nhit trung bnh thng thp nht

- Bin nhit trung bnh nm

- Bin nhit trung bnh ngy

Tiu vng - Nhit trung bnh nm

- Nhit trung bnh cc thng ma lnh

- Nhit trung bnh cc thng ma h

- Lng ma bnh qun nm

- Lng ma trung bnh ma ma

- Lng ma trung bnh ma kh

- Tim nng bc hi (PET)

- Ch s m (HI)

Bng 4. Tiu ch v kh hu cho mi phn v phn vng STLN

a cht/a mo nh hng n s hnh thnh, thnh phn loi, v.v, v phn b ca h sinh thi lm nghip thng qua nhng yu t sau:

l lc a: l khong cch t vng n bin nh hng n tiu kh hu, hnh thnh nn cc khu vc c kh hu lc a v kh hu i dng.

l cao, hng sn, dc: l nhng nhn t nh hng n ch tiu kh hu. cao hnh thnh nn cc ai cao vi c trng kh hu, th nhng khc nhau nh hng n phn b cc loi thc vt. Trong iu kin Vit Nam, gii hn vnh ai nhit i vng ni thp min Bc l 600 - 700m, min Nam l 1.000m do min Nam gn xch o hn min Bc. Thi Vn Trng (1978, 1999) phn chia thm thc vt trong mt vng thnh hai nhm ln: nhm cc qun th thc vt theo v v nhm cc qun th thc vt theo cao;

l Nn tng m khc nhau dn n hnh thnh cc loi t khc nhau;

l Nhm nhn t a cht/a mo nc ta c nh hng h sinh thi lm nghip qua cc tnh cht sau:

l Trong lch s lu di v phc tp ca qu trnh vn ng kin to, c ni c lc to iu kin thun li bo tn nhng kiu thm thc vt nguyn thu,


l H thng ni ca Vit Nam l s keo di t h thng ni min nam Trung Quc v chn dy ni Hymalaya, lin tc t Bc vo Nam, to iu kin thun li cho cc lung di c thc vt vo lnh th Vit Nam.

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

l Mt ct ngang ca dy Trng Sn khng i xng, sn ty dc thoi, sn ng dc cao ngay gn b bin. Do vy, vic phng h l rt quan trng cho min Trung.

l Do tnh him tr ca h thng ni vi ca Vit Nam nn hin nay vn cn c mt h sinh thi rng nhit i c hu m khng phi nc no cng c.

l Vit Nam keo di hn 15 v nn gii hn di ca vnh ai nhit i vng ni hai min Nam Bc khc nhau. min Bc l 600 - 700 m, min Nam l 1.000 m.

4.2.2 Phn loi

Nghin cu sm nht v phn vng a mo min Bc Vit Nam do Nguyn c Chnh, V T Lp thc hin nm 1963, sau M.A.Zubasenco thc hin nm 1967, v L c An nghin cu nm 1972, 1974, 1985.

Hai ch tiu quan trng nht trong phn vng lnh th theo a hnh/a mo l: Kin trc hnh thi (KTHT), Trm tr (Bc khm) hnh thi (TTHT).

L c An tin hnh phn vng a mo Bc Vit Nam v chia ra 57 vng. Sau khi nc nh thng nht, ng tip tc nghin cu v xy dng s phn vng a mo thng nht cho ton lnh th Vit Nam, m trc ht l phn lc a (L c An, 1979,1985). Phn vng a mo c L c An tin hnh theo 2 ch tiu ni trn ( KTHT) v (CTHT), bi l khi phn chia cc n v a mo cp bc khc nhau, ng da vo quan h gia cu trc kin to vi a hnh, lch s pht trin ca n, cc phc hp thch hc, cng nh c im ca cc qu trnh ngoi sinh, v cui cng l kt qu tc ng qua li ca cc yu t , th hin hnh thi v v tr cao ca lnh th.

4.2.3 Phn v

H thng 4 phn v ca L c An (1985) gm: Nc a mo; tnh a mo v tnh ph; min a mo v min ph. Vng a mo c Hi khoa hc t (1993) phn ra lm 4 phn v l: min (2 min), min (6 min), khu (16 khu) v vng (142 vng). Ch tiu phn chia cc vng a mo, a l t nhin v th nhng ca cc tc gi trn rt phong ph, a dng v c khi qut nh sau:

l Vng a mo: da trn c im trm tr hnh thi, v kin trc hnh thi


l Vng a l t nhin: c trng bi mt dng a hnh, mt kiu kh hu, mt dng th nhng, mt thm thc vt tng i ng nht.

l Vng a l th nhng l lnh th ton vn, ng nht v cu trc lp ph th nhng, nm trong mt vng t ai nng nghip, mt vng a l th nhng, thng mt loi t chnh quyt nh phng hng sn xut.

l Tiu ch phn chia cc vng a mo, a l t nhin, a l th nhng tng i khc nhau nhng u lin quan n a cht/a mo. y l s thng nht v cao v hnh thi a hnh (vng a mo) hay cng mt dng a hnh tng i ng nht (vng a l t nhin) hoc mt lnh th ton vn (vng a l th nhng).

l Vng sinh thi lm nghip v vng sinh thi nng nghip c din tch ln hn rt nhiu so vi cc vng a mo (v c vng a l t nhin, vng a l th nhng), thm ch ln hn c min a mo hoc khu a l th nhng hoc khu a l t nhin Ty Nguyn.

l Cc t l phn vng u l t l nh (1/1.000.000 v 1/500.000) nu so vi t l d kin ca ti l phn vng sinh thi lm nghip t l 1/250.000.

l Trong s phn vng a mo ca L c An, c 9 min, vi 16 ph min. So snh vi s phn vng a l th nhng ca Hi Khoa hc t Vit Nam, cng cng c 16 khu a l th nhng nhng ranh gii phn b ca cc ph min a mo v cc khu a l th nhng c khc nhau.

l T 16 ph min a mo, L c An phn thnh 92 vng a mo. Trong khi t 16 khu a l th nhng, cc tc gi Hi Khoa hc t Vit Nam chia thnh 142 vng a l th nhng bi v phn vng a mo l phn vng n ngnh. Nh vy, khi phn vng sinh thi lm nghip cn s ng nht ca nhiu yu t t nhin hn th ro rng s lng cc n v sinh thi lm nghip cp tng ng vng a mo c th tng ln.

l Trong s phn vng a l th nhng, khu vc Ty Nguyn c 3 khu a l th nhng v 20 vng a l th nhng. Ranh gii cc khu v cc vng a l th nhng gn nh trng vi 3 khu a l t nhin v 21 vng a l t nhin mc d cng tc nghin cu c tin hnh hai t l khc nhau vi hai i tng nghin cu khc nhau. C hai dng phn vng ny c tnh tng hp cao hn so vi phn vng a mo.

4.2.4 Tiu ch v khuyn ngh phn vng STLN

Bng 5 di y m t cc tiu ch s dng cho phn chia a hnh, a mo lin quan n phn vng sinh thi lm nghip Vit Nam (Nguyn nh K, Li Vnh Cm, 2011)


Cp phn v Tiu ch

Min Thng nht v ngun gc a hnh v c im kin to.

Vng Thng nht v hnh thi a hnh (ni, i, cao nguyn, ng bng...)

Tiu vng Tp hp thng nht ca nham thch, kiu a hnh, ai cao.

Bng 5. Tiu ch v a cht/a mo phn vng STLN

4.3 Th nhng - lp a

Th nhng v lp a l 2 nhn t khc nhau nhng lin quan mt thit vi nhau nn thng c nghin cu trong cng 1 nhn t sinh thi. Mt khc, phn loi t hay th nhng v phn loi lp a cng thuc 2 h thng l thuyt khc nhau, v y, cng trnh ny quan tm ch yu n tc ng ca th nhng v phn vng th nhng n cc tiu ch v h thng phn vng sinh thi lm nghip trn lnh th Vit Nam.


Theo nh Sm, Nguyn Xun Qut, inh Thanh Giang (2011) th phn loi t trn th gii c 3 khuynh hng chnh l:

lPhn loi t theo pht sinh (ca Docutraep V.V, cn gi l phng php a l so snh) vi 5 yu t pht sinh kh hu, a hnh, m, sinh vt v tui a cht l 5 tiu ch quan trng u tin trong phn loi t t nhin.

l Phn loi t Soil Taxanomy (M) theo quan im nh lng tnh cht v chun on nh lng tng pht sinh da trn c s quan h gia tnh cht t v hnh thi phu din phn loi t.

l Phn loi t theo FAO UNESCO l h thng phn loi mang tnh quc t trn c s tiu chun ca Soil Texonomy da vo nh lng cc tnh cht t, cc du hiu chun on phn loi t theo nhm, loi...

Vit Nam, phn loi t (thc ra cng l phn vng) tin hnh qua 3 giai on:

l Trc 1954, ch yu l cc cng trnh ca ngi Php cng bt u hng vo iu kin pht sinh pht trin tnh cht t phn chia cc nhm t, ly v d nh nhm t latritic v nhm t ph sa ca Castagnol E.M (1950).

l T 1954 n 1975, min Bc c phn loi t theo a l pht sinh ca Fritlan V.M v cc nh th nhng Vit Nam (1959); min Nam c phn loi t chu nh hng ca trng phi Soil Taxanomy do Moormann F.R ch bin (1960).


l T 1975 n 2010 xy dng phn loi t ton quc dng cho bn t Vit Nam t l 1/1000.000 (1980) hon thin theo quan im pht sinh hc c 13 nhm vi 30 loi v bng phn loi t quc gia theo phng php nh lng FAOUNESCOWRB (1998) va c quan h gn b vi phn loi trn, va hi nhp.

H thng phn loi t Vit Nam theo h thng 4 cp: Nhm loi (n v) loi ph (n v ph ) bin chng. Nhm v loi theo quan im v ch tiu nh phn loi t quc t v ph hp vi thc trng t Vit Nam. Loi ph c th hin c mc v su xut hin kt von, gly nhiu - t, nng - su. Bin chng s dng quan h thnh phn c gii t c quan h vi m theo 3 cp hoc 6 cp. V phn loi lp a, nh hng vo Vit Nam cng c 3 xu hng, chng khc nhau cp bc phn loi, tiu ch v ch s xc nh:

l Phng php phn vng lp a lm nghip vi 4 cp phn v do chuyn gia Cng ho dn ch c chuyn giao t 1970, v ang c s dng c hiu qu trong c nc cho n nay.

l Trng phi Lin x c do Tchertov (1977, 1981) p dng th vi 3 tiu ch: m, a hnh, thot nc.

l xut t nghin cu v thc tin phn loi 6 cp lp a ca Nguyn Vn Khnh (1996).

4.3.2 Phn loi

Hai h thng phn loi t Vit Nam l: I) Phn loi theo pht sinh t l 1/1.000.000 (Ban bin tp bn t Vit Nam, 1976). H thng ny a ra 13 nhm t v 30 loi t; v II) H thng phn loi theo FAO-UNESCO (Vin Quy hoch Thit k Nng nghip 1998). H thng phn loi ca FAO-UNESCO c 4 cp sau:

l Nhm t chnh (Major soil groupings)

l n v t (Soil units) tng ng loi t theo phn loi pht sinh

l n v ph (Soil Sub-units)

l Pha t hay tng t (Phase)

n v t l n v phn loi c bn. Bng phn loi c 21 nhm t chnh v 61 n v t. Trong 61 n v t th c 28 n v t lin quan n sn xut lm nghip. Chi tit v tn nhm t v n v t xem Ph lc 1 v bn phn b cc n v t Ph lc 2.


4.3.3 Phn vng a l th nhng

H thng phn vng a l th nhng gm 4 cp l: Min, min, khu v vng. Da trn bn t phn loi theo pht sinh t l 1/1.000.000, Ban bin tp bn t Vit Nam xy dng d tho phn vng a l th nhng. Cc c im ca phn vng ny gm:

l Min: chia ra 2 min a l th nhng vi ranh gii t nhin l o Hi Vn l min a l th nhng pha Bc v min a l th nhng pha Nam.

l min: Chia ra 6 min trong phm vi ca 2 min, khc nhau v kh hu, thy vn, th nhng v sinh vt. Min Bc c 3 min, min Nam cng c 3 min.

l Khu: c chia ra trong phm vi min da trn s khc nhau v a cht a mo v c im s dng t nng nghip. Min Bc c chia ra 8 khu v min Nam cng c 8 khu.

l Vng: L n v phn vng c s thp nht. Da trn bn t Vit Nam t l 1/1.000.000 xy dng nm 1976 cho c nc th c 142 vng ca 16 khu a l t nhin.

4.3.4 Phn vng lp a

Lp a l mt phm vi lnh th nht nh vi tt c nhng yu t ca ngoi cnh nh hng ti sinh trng ca sinh vt m ch yu l thc vt. Theo ngha hp lp a bao gm 3 thnh phn: kh hu, a hnh, th nhng; theo ngha rng n bao gm 4 thnh phn: kh hu, a hnh, th nhng, th gii ng thc vt.

Phn vng lp a lm nghip ca chuyn gia Cng ha dn ch c Vit Nam, 1970 gm 4 cp phn v: l Vng sinh trng

l Khu sinh trng

l Phm vi bc khm

l Dng lp a.

Cc tc gi phn min Bc thnh 7 vng sinh trng v 22 khu sinh trng. xut phn vng lp a ca Nguyn Vn Khnh (1996) gm 6 cp phn v l: min, min, vng, tiu vng, dng t ai v dng lp a.


4.3.5 Tiu ch v khuyn ngh phn vng STLN

Cc chuyn gia t v lp a thy rng phn v Min phn chia theo chiu di 15 v do to ra 2 vng kh hu khc nhau l vng nhit i in hnh Min Nam, v nhit i khng in hnh (c ma lnh 1-3 thng) Min Bc, nhng s khc nhau v phn loi t v lp a th khng ro net, so vi chnh lch v cao hnh thnh lp t nhit i v nhit i in hnh. Do vy, s ng gp ca nhn t t lp a i vi phn vng STLN ch yu vo phn v nh hn l vng v tiu vng thng qua tiu ch phn loi theo pht sinh 13 nhm t (lp ph) v 30 loi t. Ba c s xut tiu ch t - lp a tham gia phn vng STLN l:

l Phn loi cc kiu rng hay h sinh thi t nhin.

l Cc cp phn v chn theo mc tiu nghin cu.

l Quan h gia loi t v loi rng, ni cch tng qut l gia t ai v qun x thc vt.

Hai c s u c xc nh trong cc m t trn, c s th 3 chnh l quy lut ph hp gia sinh vt v ngoi cnh. Mi loi t ch c th ph hp cho mt hay mt s loi rng, ngc li mi loi rng cng ch mc c trn mt hoc mt s loi t gii hn no .

Tng hp kt qu xut phn chia ca cc nhm, la chn, thng nht cc cp phn v, v xut dng bn .

Nguyn tc chn phn v:

Ba phn v la chn l min, vng v tiu vng, trong vng v tiu vng l cc phn v ch yu. Phn vng sinh thi cn phi da trn mt n v c bn, t n v c bn ny s c cc n v cp trn v n v cp di theo h thng phn cp. Nh vy theo nhim v ca d n th n v vng sinh thi lm nghip phi l n v c bn. n v cp trn c th gi l khu v trn na l min. Trong bng xut ny tm coi tiu vng l n v c bn v n v trn l vng v min. V nu gi tiu vng l vng th vng phi gi l khu (s khng quen vi nhng ngi lm nghip hin nay).

Cc tiu ch phn chia vng:

l C s ng nht tng i v mt kiu kin trc a cht a mo, cng lch s pht trin to nn mt hnh thi i a hnh c c trng bi s phn ha khng ln v kh hu, th nhng di s tc ng tng h ca hon lu v a hnh.


l C nhng c im tng ng v ngun gc pht sinh, lch s pht trin v cu trc ca cc qun h thc vt.

l C chung c im cng ng dn tc to nn mc tng ng v tc ng k thut vo t nhin.

l C tnh ton vn lnh th (khng lp li), tng i thng nht v ranh gii a chnh cp tnh (mt tnh khng nn nm trong hai vng).

Cc tiu ch phn chia tiu vng:

l C cng mt dng cnh quan ng nht tng i v nn m v hnh thi a hnh; tiu kh hu; n v t v cc qun x thc vt.

l Tng i ng nht nn nhit m v cc nhn t ch o hnh thnh kiu rng v nng sut.

l C ranh gii nm gn trong 1 vng sinh thi lm nghip v bo m khng tch bit v mt khng gian i vi mt tiu vng.

l C s ng nht v phng thc s dng t.


Cp phn v Tiu ch M t

Vng La chn t nht

3 nhm t chnh

(theo FAO/UNESCO)

trong 13 nhm.

I. t ct (Arenosols); II. t mn (Solochats); III.t ph sa

(Fluvisols); IV. t phn (Thionic Fluvisols); V. t gley (Gleys-

ols); VI. t than bn (Hitosols); VII. t en (Luvisols); VIII. t

nu (Lixisols); IX. t tch vi (Calcisols); X. t xm (Acrisols);

XI. t (Ferralsols); XII. t mn alit ni cao (Alisols); XIII. t

xi mn tr si (Leptosols).

Tiu vng La chn t nht 2

n v t chnh (soil

Units) theo FAO-

UNESCO trong s 28

n v t.

1. Cn ct trng vng (Luvic Arenosols); 2. Cn ct (Rhodic

Arenosols); 3. Ct in hnh (Haplic Arenosols); 4. t mn s

vt (Gleyic Solochats); 5. t phn tim tng (Proto-thionic

Gleysoils); 6. t phn hot ng (Orthi-thionic Fluvisols); 7.

t gley chua (Dystric Gleysols); 8. t ly (Umbric Gleysols);

9. t than bn (Fibric Histosols); 10. t than bn phn tim

tng (Thionic Histosols); 11. t en c tng kt von dy (Fer-

ric Luvisols); 12. t en Cacbonat (Calcic Luvisols); 13. t

nu thm (Chromic Luvisols); 14. t nu thm tch vi (Luvic

Calcisols); 15. t vng tch vi (Haplic Calcisols);16. t xm

bc mu (Haplic Acrisols); 17. t xm Ferralit (Ferralic Ac-

risols); 18. t potdon gly (Gleyic Podzoluvisols); 19. t nu

(Rhodic Ferallsols); 20. t nu vng (Xanthic Ferrasols); 21.

t vng vng set loang l (Plinthic Ferrasols); 22. t mn

vng trn ni (Humic Ferrasols); 23. t xm mn trn ni

(Humic Arisols); 24. t mn alit ni cao (Humic Alisols); 25.

t mn alit ni cao gley (Gleyic Alisols); 26. t mn than bn

ni cao (Histric Alisols); 27. t nu tm (Haplic Nitisols); 28.

t xi mn tr si (Lithic Leptosols).

Bng 6. xut tiu ch phn chia th nhng trong phn vng STLN

4.4 Phn vng STLN


Phn vng sinh thi lm nghip tuy rt gn vi phn vng sinh thi nng nghip v cng mc tiu bo tn v s dng bn vng t ai, tng nng sut cc h sinh thi thc vt, cng s dng cc ti nguyn thin nhin v ngun lc x hi. cc nc nhiu rng, c bit l cc nc pht trin, m kinh t lm nghip c t trng cao trong nn kinh t quc dn nh Thy in, Na Uy, Phn Lan, Lin x c, Canada, M, v.v, th thng vic phn vng lnh th c hon thnh v a vo s dng ngay t u v gia th k XX. S khc nhau ca cng tc phn vng l mc tiu, ni dung v


phm vi lnh th cho nn c cc tn gi khc nhau nh: Phn vng lm nghip, phn vng kinh t lm nghip, phn vng sinh thi lm nghip, v.v. Lin X (c)l quc gia nhiu rng v nhiu thnh tu v phn vng lnh th lm nghip, mi chuyn khng ch cho Lin bang, m cn cho cc nc cng ha.

Theo Li Vnh Cm th vng sinh thi c nh ngha l vng a l xc nh, nh hn i sinh thi nhng ln hn h sinh thi. Omernik (2004) a ra nh ngha vng sinh thi nh sau: vng sinh thi l vng m trong c ng nht khng gian v cc c trng a l gn vi s phn ha v cht lng, sc khe v s ton vn ca cc h sinh thi. Cc c trng a l c th gm a cht, a l t nhin, thc vt, kh hu, thy vn. Cc h ng vt trn cn v thy vc, t v c th c hoc khng c tc ng ca con ngi (v d s dng t, s thay i thm thc vt).

Nm 2001, WWF hon thnh h thng phn loi phn vng sinh thoi ton cu (Ecoregions of the World). H thng ny bao gm cc cc n v vng tng i ln c nhng c im ring v mt a l, iu kin kh hu v c cc qun th t nhin c trng. Vng sinh thi cn phn nh s phn b t nhin ca loi v qun th sinh vt trc khi c s tc ng ca con ngi. H thng bn phn vng sinh thi ton cu c rt nhiu ng dng trong cc nghin cu v sinh thi v a dng sinh hc:

l Cung cp c s v a l sinh hc cho cc chin lc bo tn quy m ln;

l Cung cp bn lm c s cho vic hoch nh cc d n bo tn mc ton cu v mc vng;

l Cung cp c s khoa hc v iu kin t nhin ca cc vng sinh thi bao gm kh hu, t ai, thm thc vt, ng vt, tnh trng hin ti v cc mi nguy hi tc ng ti h sinh thi t nhin.

Theo phn vng ny, WWF chia b mt phn t ni ca tri t thnh 8 i sinh thi (ecozone) vi 867 vng sinh thi v khong 450 vng sinh thi thy vc trn ton th gii. Vit Nam c 14 vng sinh thi (eco-regions) nh sau (xem chi tit bn ):

1. Rng ma ni Cardamom (k hiu: IM0106)

2. Rng ma ni cao Luang Prabang (k hiu: IMO121)

3. Rng ma Bc Annamites (k hiu: IM0136)

4. Rng nhit i Bc Indochina (k hiu: IM0137)

5. Rng ma t thp min Bc Vit Nam (k hiu: IM0141)

6. Rng m ly nc ngt sng Hng (k hiu: IM0147)

7. Rng thng xanh nhit i Nam Trung Hoa Vit Nam (k hiu: IM0149)


8. Rng ma ni cao Nam Annamites (k hiu: IM0152)

9. Rng m ly nc ngt Tonle Sap (k hiu: IM0164)

10. Rng m ly nc l Tonle Sap-Mekong (k hiu: IM0165)

11. Rng kh trung tm Indochina (k hiu: IM0202)

12. Rng thng xanh kh Ty Nam Indochina (k hiu: IM0210)

13. Rng kh t thp Nam Vit Nam (k hiu: IM0211)

14. Rng ngp mn Indochina (k hiu: IM1402)

Qun o Hong Sa

Qun o Trng Sa


H thng phn vng ca WWF cho thy cc kt qu trn c thc hin quy m ln (ton cu) nn cng ch mang tnh khi qut. Do vy, cc nh khoa hc thuc nhiu quc gia ang tip tc nghin cu chi tit hn v phn chia t l ln hn. Vic xem xet, nh gi cc kt qu nghin cu ny c ngha to ln cho cng tc nghin cu phn vng sinh thi lm nghip nc ta.

Ti Vit Nam, trc nm 1975, Tng cc Lm nghip thng s dng khi nim vng lm nghip vi ngha l mt n v hnh chnh c nhiu hot ng lm nghip tp trung qun l v quy hoch pht trin, in hnh nht l vng lm nghip sng Hiu (huyn Qu Chu v Qu Hp) tnh Ngh An.

Sau nm 1975 mt lot vng lm nghip tng t c thnh lp ti min Nam Vit Nam sau ngy thng nht t nc. Cc vng ny em tnh cht khu kinh t lm nghip v an ninh, sau ng lot chuyn thnh cc Lin hip sn xut (corporation). Khng c phng php, tiu ch phn vng, m ch quy hoch cho nhng ni giu g nn khng em tnh cht phn vng lnh th.

Khi nim th hai l 9 vng lm nghip bao trm ton lnh th cng c s dng t thp nin 1970 cho n ngy nay trong vic quy hoch v m, qun l ngnh. N rt gn khi nim phn vng lnh th theo ngnh kinh t lm nghip. Song v khng c cng trnh phn vng, khng c phng php lun v khng c tiu ch phn vng, cng khng c mt cp thm quyn no ph duyt, ban b, cng l mt nghch l tn ti lu nm, c th do n rt ging 7 vng sinh thi nng nghip, v ging 7 vng t nhin ca kh hu nn vn pht huy hiu qu s dng.

Tm li, s lng n v cp tnh v tn tnh trong mi vng tng thay i do qu trnh tch tnh, nhp tnh, hin nay chng nh sau:

l Vng Ty Bc: gm 4 tnh l Ha Bnh, Sn La, in Bin, Lai Chu.

l Vng ng Bc: gm 12 tnh: Cao Bng, Lng Sn, Bc Cn, Thi Nguyn, Qung Ninh, Bc Giang, Lo Cai, Yn Bi, H Giang, Tuyn Quang, Ph Th, Vnh Phc.

l Vng ng bng Bc B: gm 9 n v tnh: Hi Phng, Hi Dng, Bc Ninh, Hng Yn, H Ni, Thi Bnh, Nam nh, H Nam, Ninh Bnh.

l Vng Bc Trung B: gm 6 n v tnh: Thanh Ha, Ngh An, H Tnh, Qung Bnh, Qung Tr, Tha Thin-Hu.

l Vng Nam Trung B: gm 8 n v tnh: Nng, Qung Nam, Qung Ngi, Bnh nh, Ph Yn, Khnh Ha, Ninh Thun, Bnh Thun.

l Vng Ty Nguyn: gm 5 n v tnh: Lm ng, k Nng, k Lk, Gia Lai, Kom Tum.


l Vng ng Nam B: gm 6 n v tnh: B Ra-Vng Tu, ng Nai, Bnh Dng, Bnh Phc, Ty Ninh, thnh ph H Ch Minh.

l Vng Ty Nam B: gm 13 n v tnh: Long An, Bn Tre, ng Thp, Sc Trng, Vnh Long, Cn Th, Hu Giang, Tin Giang, Bc Liu, C Mau, Kin Giang, An Giang, Tr Vinh.

4.4.2 Phn loi

Ni dung ca cng trnh ny l phn vng lnh th Vit Nam thnh cc cp n v din tch nh hn nhng thun nht hn v HSTR, v cung cp cc c s d bo nng sut sinh hc ca h sinh thi v ca lp a khi cha c rng, do vy, ngay mc 4.2 phn loi cc cng trnh phn vng sinh thi Vit Nam. Ti mc 3.3 trnh by cc phng php, kt qu v phm vi ng dng cc h thng phn loi rng, v lun gii vic la chn h thng cc HSTR phn loi theo Cm nang ngnh Lm nghip (c b sung cc h sinh thi ang hin hu trn lnh th Vit Nam) do tnh khoa hc v tnh hin thc ca h thng.

4.4.3 Lun gii v la chn phn v

Vn l thuyt t ra y l chn cc phn v th no p ng mc tiu phc v xc nh ng pht thi tham kho (REL) v h tr cng tc gim st, bo co, nh gi (MRV), ng thi c th s dung cho quy hoch pht trin ngnh v qun l v m, m khng phc v vic xc nh tng sinh khi hay lng pht thi, ca cc n v qun l rng, kinh doanh rng c th. Do trong h thng 7 cp phn v hng dn trong Thng t 193/UB-VP, cng trnh chn cp Vng v cp Tiu vng (tng ng cp cnh quan sinh thi), y l 2 cp trung bnh v c nhiu cng trnh tng t, thc t cp vng c tt c mi cng trnh coi l cp c bn.

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