Transcript Direct and indirect effects of global change on species

Direct and indirect effects of global
change on species responsiveness,
invasion success and weed performance
in dry regions
José M. Grünzweig
Robert H. Smith Faculty of Agriculture, Food and
Environment, the Hebrew University of Jerusalem, Israel
2 International Conference on «Novel and sustainable weed management in arid
and semi-arid agro-ecosystems», Santorini, Greece, 8 September 2009
nd
Outline
1.
Global change as a complex concept in ecology,
agronomy and plant science
2.
Responsiveness to global change of plant
species in general and weeds in particular
3.
Invasive species in natural and agricultural
ecosystem under global change
4.
Conclusions: Weed success and invasion at
different spatial scales in arid and semi-arid
regions under future changed conditions
1. Global change as a complex concept in ecology,
agronomy and plant science
U.S. Global Change Research Act of 1990
Public Law 101-606(11/16/90) 104 Stat. 3096-3104
"Global change" means changes in the global
environment (including alterations in climate,
land productivity, oceans or other water
resources, atmospheric chemistry, and ecological
systems) that may alter the capacity of the Earth
to sustain life.
Change in atmospheric composition
Climate change
Nitrogen deposition
Change in stratospheric ozone
Tropospheric ozone pollution
...
Atmospheric
CO2 enrichment
Land use change and anthropogenic disturbance
Alien species invasion
A. Danin
A. Danin
Barry A. Rice
2. Responsiveness to global change of plant
species in general and weeds in particular
• Differential response of species and
possible mechanisms underlying those
responses
• Potential relevance for agricultural weeds
Differential impact of global change on plant species
Global change manipulation in a ‘natural’ grassland in California:
• Atmospheric CO2 enrichment (C)
• Climatic warming (W)
• Rain (precipitation) addition (P)
• Atmospheric nitrogen deposition (N)
Species

 = increase
 = decrease
= inconsistent
response
0 = no change
Modified from Zavaleta et al. 2003 Ecol. Monogr.
Aboveground biomass (g m-2)
Change in aboveground biomass (g·m-2)
Impact of global change on plant species: example from a
semi-arid community under atmospheric CO2 enrichment
25
20
Onobrychis crista-galli
P = 0.009
440-280
15
300
a
b
b
200
100
0
280
440
600
CO2 concentration (ppm)
600-280
10
A.s.
5
P.f. M.m.
C.d.
H.c.
B.f.
P.p.
C.a. P.co. B.a.
P.a.
D.s.
B.l.
Bi.d.
0
H.s.
H.c.
M.t.
T.c.
S.c.
H.u.
R.s.
D.g.
R.p.
Br.d.
P.cr.
-5
Species
Grünzweig & Körner. 2001. Oecologia. Grünzweig & Körner. 2001. Oikos
R.a. S.p.
Some growth-determining plant factors that can be altered
by elevated CO2
• Photosynthetic rate
• Stomatal conductance
• Respiration rate (differences between different plant
parts)
• Partitioning of dry matter (leaf vs. stem, roots or storage
organs)
• Leaf duration (leaf senescence)
LWRa
• Allocation of carbon to symbionts and exudation
0.4
0.3
0.2
0.1
0.0
280 440 600
CO2 concentration (ppm)
Leaf weight ratio (LWRa = leaf
DW / total aboveground DW)
for Onobrychis crista-galli
Water saving under atmospheric CO2 enrichment as indirect effect
on plant performance and species composition
Low CO2
High CO2
Evapotranspiration
Rain
28
7
39
7
Soil moisture
Water leaching
Period during growing season
Morgan et al. 2004. Oecologia
Onobrychis crista-galli: the largest species
and the most mesic legume in the community
Seed production at elevated CO2
Onobrychis crista-galli
Parentucellia flaviflora
Seed production (no. m-2)
1200
600000
P = 0.001
P = 0.010
800
400000
400
200000
0
0
280
440
600
CO2 concentration (ppm)
280
440
600
CO2 concentration (ppm)
A. Danin
Competition between a semi-arid C4 pasture grass and an
invasive C3 weed under atmospheric CO2 enrichment
P.h.:C.c. = 1:1
Cenchrus ciliaris
introduced C4 pasture grass in semiarid subtropical and tropical
pastures of northern Australia
Parthenium hysterophorus
invasive C3 weed
P.h.:C.c. = 1:3
Potential causes of increased growth
and reproduction of P. hysterophorus
under elevated CO2:
Plant water savings and accelerated
plant development under conditions
of rapid soil drying
Invasive weeds under past and future atmospheric CO2 enrichment
Potential causes of
increased growth under
elevated CO2:
Substantial belowground
sinks contributing to largely
stimulated plant growth
→ potential link between
invasiveness and CO2
responsiveness
Increase in total biomass (%)
Ziska. 2003. J. Exp. Bot.
Hemiparasite performance under global change
Phoenix & Press. 2005. Folia Geobot.
Responses of C3 and C4 species to global change
Atmospheric CO2 enrichment
Higher sensitivity of C3 vs. C4 photosynthesis to elevated CO2
Stimulation of C4 relative to C3 species by elevated CO2 under
warm and dry conditions
Climate change
Global warming: favors C4 plants in general
Timing of global warming:
Warmer winters → stimulation of C3 plants
Warmer and wetter summers → stimulation of C4 plants
Warmer and drier summers → suppression of C4 plants
(unless fire plays a role in the ecology of the site)
3. Species invasiveness in natural and agricultural
ecosystems under global change
Lectures to be learned from natural
ecosystems and potential application to
invasive weeds in an agricultural context
Skinner et al.
2000. Weed Sci.
Enhancement of an invasive annual grass under
atmospheric CO2 enrichment in the desert
Success of the invasive alien Bromus madritensis spp.
rubens in the Mojave Desert FACE experiment
Smith et al. 2000. Science
Positive feedback loops of alien plant invasion
Invasive alien cheatgrass (Bromus tectorum)
Yield losses and costs for weed control (W USA,
Canada): US$ 350-375 million/year
Evans et al. 2001. Ecol. Appl.
Mediterranean islands
Plant invasion on Mediterranean islands
Human-dominated habitats
Habitat
Modified from Hulme et al. 2008 In: Tokarska-Guzik et al., Backhuys Publishers
Impact of climate and land use on plant invasions
Oxalis pes-caprae
invasion on the
island of Crete
(Greece)
Initial bulbil biomass
Barry A. Rice
Agricultural sites
colonized by
Oxalis pes-caprae
Ross et al. 2008 Persp. Plant Ecol.
Evol. Syst.
Model output on the effect of disturbance frequency on native
and invasive species on the island of Lesbos (Greece)
Juniperus oxycedrus
Quercus coccifera
Quercus ilex
Ailanthus
altissima
Gritti et al. 2006. J. Biogeogr.
Model output on the effect of disturbance frequency on native
and invasive species on the island of Lesbos (Greece)
Ailanthus altissima (invasive tree)
Amaranthus retroflexus (invasive C4 herb)
Plantago lanceolata (native herb)
Different native trees and shrubs
Gritti et al. 2006. J. Biogeogr.
Theory of alien invasions can suggest causes for
successful invasive weeds
a) Increased resource availability
b) Enemy release
Davis. 2000. J. Ecol.
Combination of a) and b)
Blumenthal. 2005. Science
Invasive species
Keane & Crawley. 2002
4. Conclusions: Weed success and invasion at
different spatial scales in arid and semi-arid
regions under future changed conditions
High responsiveness to global change
Ecophysiological topics
• Large aboveground or belowground sinks
• Efficient carbon allocation and canopy development
Rainfed agriculture
• Water waster in a water-saving system
• Accelerated growth and development
C4 weeds
• Higher water use efficiency
• Better adapted to elevated temperatures and heat stress
than C3 plants
Hemiparasites
Effects of host water, carbon and nutrient relations
Plant invasiveness and site conditions prone to invasion
• Drying → gaps in the vegetation as opportunity for
establishment and integration
• Land use change, fire and disturbance → extensive
opportunity for establishment and integration under increased
resource availability, leading to high propagule pressure
• High propagule pressure → spread
• Warming → competitive advantage (C4) for integration and
spread
• Elevated CO2 → competitive advantage (species with large
seed or belowground sinks) for integration and spread