Native Grass Seeding and Native Grass Seeding and M ulch Effects on Weedy M ulch Effects on Weedy

Species:Species:a linkage between weeds and restorationa linkage between weeds and restoration

Michael HoganMichael HoganIntegrated Environmental Restoration Services, Integrated Environmental Restoration Services,

Inc.Inc.

Tahoma, CATahoma, CArevegetaterevegetate@@ earthlinkearthlink.net.net

Lake Tahoe, MicrocosmLake Tahoe, Microcosm

The IssuesThe Issues

•• Water quality is dependant upon soilWater quality is dependant upon soil

•• Plant growth is dependant upon soilPlant growth is dependant upon soil

•• Erosion control is dependant upon soilErosion control is dependant upon soil

•• Weed growth is dependant upon soilWeed growth is dependant upon soil

•• What do we know about the soil?What do we know about the soil?

•• Habitat restoration is difficult or Habitat restoration is difficult or impossible without stable soilimpossible without stable soil

•• Erosion control has been agricultural Erosion control has been agricultural in approachin approach

•• 25 years, little progress…25 years, little progress…

The JourneyThe Journey

Asking the (soil) QuestionsAsking the (soil) Questions

•• What’s missing? What’s missing? (disturbance)(disturbance)

•• How to put it backHow to put it back…(restoration)…(restoration)

•• What will grow? What will grow? (restoration)(restoration)

•• How do we stop the weeds? How do we stop the weeds? (restoration)(restoration)

•• Do we ‘Do we ‘stopstop’ the weeds?’ the weeds? (ecological)(ecological)

W hat’s Missing?W hat’s Missing?

MM

SOILSOILSOILMicrobesMicrobes

WaterWater PlantsPlants

DecompositionDecomposition

UptakeUptake

BYE!!BYE!!MulchMulch

What’s Missing?What’s Missing?Total N in Disturbed Tahoe Soils Total N in Disturbed Tahoe Soils

±1.96*Std. Err.±1.00*Std. Err.Mean

Volcanic Soil N total0-50 cm layer sum

Veg Level

N to

tal

kg h

a-1

200

600

1000

1400

1800

2200

2600

0-10 10-40 >40

Claassen and Hogan, 2002 Restoration Ecology v.10,#2 pg 195-203

What’s Missing, the rest of the N storyWhat’s Missing, the rest of the N story

Regression95% confid.

% plant cover vs. mineralizable NH4

% plant cover

min

eral

izab

le N

H 4 (k

g N

/ha)

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80

r2=0.4723

Regression95% confid.

% plant cover vs. extractable NO3

% plant cover

ext

ract

able

NO

3 (kg

N/h

a)

0

2

4

6

8

0 10 20 30 40 50 60 70 80

r2= .0172

% plant cover vs. total N

% plant cover

tota

l N (k

g N

/ha)

0

400

800

1200

1600

2000

0 10 20 30 40 50 60 70 80

r2=0.4662

% plant cover vs. extractable NH4

% plant cover

ext

ract

able

NH

4 (kg

N/h

a)

0

2

4

6

8

0 10 20 30 40 50 60 70 80

r2=0.0693

Claassen and Hogan, 2002 Restoration Ecology v.10,#2 pg 195-203

.

Replacing N: Soil Replacing N: Soil Am endm entsAm endm entsU C D avis S oils and R evegetation

S and Leaching C olum n Experim ent

0

5 0 0

1 0 0 0

1 5 0 0

2 0 0 0

2 5 0 0

3 0 0 0

3 5 0 0

4 0 0 0

4 5 0 0

5 0 0 0

1 2 3 4 5 6 7 8 9 1 0 1 1 1 2

le ach in g e ve n t

mg NH4/L solution

scu

p 4 0

o s

uf

m u

b s

rn

co

ap

g p

Claassen and Hogan, 1998 National Technical Information Service rept. # FHWA/CA/TL 98/18

Replacing N: Com postsReplacing N: Com posts

N i t r o g e n y ie ld ( p e r c e n t o f t o t a l N lo a d e d ) o v e r a 4 8 0 d a ya e r o b ic i n c u b a t io n o f s o i l s a n d a m e n d e d s o i l s ( m in u s c o n t r o l s u b s t r a t e ) .

d a y s0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0

% o

f N

lo

ad

ed

0

5

1 0

1 5

2 0

2 5

3 0Y W C 1Y W C 2Y W C 3Y W C 4C C M 1C C M 2G T G SS TS SD G

0

C C M - 2C C M - 1

G S

S T

D GY W C - 2

G TY W C - 3Y W C - 4

S S

Y W C - 1

N i t r o g e n y ie ld ( p e r c e n t o f t o t a l N lo a d e d ) o v e r a 4 8 0 d a ya e r o b ic i n c u b a t io n o f s o i l s a n d a m e n d e d s o i l s ( m in u s c o n t r o l s u b s t r a t e ) .

d a y s0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0

% o

f N

lo

ad

ed

0

5

1 0

1 5

2 0

2 5

3 0Y W C 1Y W C 2Y W C 3Y W C 4C C M 1C C M 2G T G SS TS SD G

0

C C M - 2C C M - 1

G S

S T

D GY W C - 2

G TY W C - 3Y W C - 4

S S

Y W C - 1

Compost N Yield, 480 days

Carey, Jan; 2002, UC Davis Masters Thesis

Soil amendments, mulches, Soil amendments, mulches, weeds…weeds…

Where it the Where it the CheatgrassCheatgrasscoming from??coming from??

•• CompostCompost

•• MulchMulch

•• Seed bankSeed bank

•• Blowing in?Blowing in?

Succession and com petitionSuccession and com petitionHigh N availability=high early High N availability=high early seralseralweedsweeds

(Bernese&Aerts, 1984; Heil&Brugggink 1987)

Initial Study ResultsInitial Study Results

•• TreatmentsTreatments

–– Compost + BiosolCompost + Biosol

–– BiosolBiosol

–– Mulch (no Mulch (no addt’laddt’l nutrients)nutrients)

•• Results:Results:

Bromus Bromus tectorumtectorum response to compost response to compost mulch and nutrientsmulch and nutrients

••Pe

rcen

t Br

omu

s Pe

rcen

t Br

omu

s te

ctor

umte

ctor

umin

plo

tin

plo

t

0

10

20

30

40

50

60

70

80

slope 5 slope 6 slope 7

C om p

B iosol

C ontrol

Soil Restoration:Soil Restoration:Other VariablesOther Variables

•• CompactionCompaction

•• WaterWater

•• Water holding capacityWater holding capacity

•• InfiltrationInfiltration

•• WaterWater

•• HH22OO

•• MicroorganismsMicroorganisms

•• Other nutrients (macro and micro)Other nutrients (macro and micro)

Other VariablesOther Variables

•• CompetitionCompetition

•• Native GrassesNative Grasses•• Francis & Francis & PykePyke 1996 1996

–– Wheatgrass (Wheatgrass (NordenNorden, , HycrestHycrest))

–– 130130--520 seeds m520 seeds m22

•• Herron, Herron, SheleySheley, Maxwell & Jacobsen , Maxwell & Jacobsen 20012001–– BluebunchBluebunch, annual Rye, Squirreltail, annual Rye, Squirreltail

–– 3000 seeds m3000 seeds m22

•• Northstar Unit 7Northstar Unit 7–– 3000 seeds m3000 seeds m22

–– < 1% Bromus < 1% Bromus tectorumtectorum

Other Variables IIOther Variables II•• Soil Physical TreatmentSoil Physical Treatment

Ecosystem Trajectories Ecosystem Trajectories vsvs Weed TrajectoriesWeed Trajectories

Restoration

Original Ecosystem

Biomass and nutrient accumulation

Species and complexity

Rehabilitation

Neglect?

Replacement

Original material or Degraded ecosystem

Replacement

Weeds

After Bradshaw and Chadwick, The Restoration of Land 1980

Weeds and Restoration:Weeds and Restoration:W here do we go from here?W here do we go from here?

••TestingTesting

••Adaptive ManagementAdaptive Management