biological mediation of invasive plant impacts in ecosystems
DESCRIPTION
Biological mediation of invasive plant impacts in ecosystems. Duane A. Peltzer Landcare Research Lincoln, New Zealand. What is covered in this talk?. NZ weeds and ecosystem processes What are weed impacts? Field removal experiments. NZ Background. - PowerPoint PPT PresentationTRANSCRIPT
Biological mediation of invasive plant impacts in ecosystems
Duane A. PeltzerLandcare Research
Lincoln, New Zealand
1.NZ weeds and ecosystem processes
2.What are weed impacts?
3.Field removal experiments
What is covered in this talk?
NZ Background
• > half of NZ’s flora is naturalised non-native plants; many are weeds
• Weeds are widely thought to reduce biodiversity and alter ecosystem processes
• >340 weed species are currently managed
IMPACT = DISTRIBUTION x ABUNDANCE x
EFFECT
Predicting weed impact
Least well understood, include:• Gene-flow• Biogeochemical changes (C, N, P)• Disturbance regime• Ecosystem engineers• Interaction modification
Weed effects
Understanding what controls the ecosystem-level impacts of exotic species as a basis for management
Invasion Ecology
root feeding fauna
mycorrhiza
pathogens
direct pathway to plants indirect pathway to plants
detritus foodweb
a
c1c2
b1b2
After Cote et al. 2005 ARES
Modest effects
Reversible threshold effects
Non-reversible threshold(different stable states)
Kowhai River, Kaikoura, NZ
Dominant exotic
Buddleja davidiiCoriaria arborea
Dominant native
~97% of total plant biomass
~15 species<0.1% of biomass
~25 species~3% of biomass
Other exotics Other natives
Peltzer et al. 2009 Oikos 118: 1001
+C+B+N +C+B-N +C-B+N -C+B+N -C+B-N -C-B+N
+C-B-N
-C-B-N
Nat
ive
alph
a di
vers
ity (
spec
ies
richn
ess)
0
4
6
2
2002 2003 2004 2005
a b
2002 2003 2004 2005
Year
+C+B+N +C+B-N +C-B+N -C+B+N -C+B-N -C-B+N
+C-B-N
-C-B-N
Nat
ive
alph
a di
vers
ity (
spec
ies
richn
ess)
0
4
6
2
2002 2003 2004 2005
a b
2002 2003 2004 2005
Year
Dickie et al. 2010 New Phytologist
Nematode community shifts
Dehlin et al. 2008
Preferred Not selected Avoided
Forsyth et al. 2002, Richardson et al. unpublished
Kurokawa, Peltzer, Wardle 2010 Functional Ecology
Kurokawa, Peltzer, Wardle 2010 Functional Ecology
PossumsRats
Vegetation/fruit
Inverts?
Birds
Control
Key points
• Small species matter!
• Weeds have biological legacies + change ecosystem processes (effects)
• Containment or early control is best
Peltzer et al. 2010 GCB 16:732.
