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Direct and indirect effects of global change on species responsiveness, invasion success and weed performance in dry reg

José M. Grünzweig Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University of Jerusalem, Israel. Direct and indirect effects of global change on species responsiveness, invasion success and weed performance in dry regions.

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Direct and indirect effects of global change on species responsiveness, invasion success and weed performance in dry reg

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  1. José M. Grünzweig Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University of Jerusalem, Israel Direct and indirect effects of global change on species responsiveness, invasion success and weed performance in dry regions 2nd International Conference on «Novel and sustainable weed management in arid and semi-arid agro-ecosystems», Santorini, Greece, 8 September 2009

  2. Outline • Global change as a complex concept in ecology, agronomy and plant science • Responsiveness to global change of plant species in general and weeds in particular • Invasive species in natural and agricultural ecosystem under global change • Conclusions: Weed success and invasion at different spatial scales in arid and semi-arid regions under future changed conditions

  3. 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.

  4. Change in atmospheric composition Climate change Nitrogen deposition Change in stratospheric ozone Tropospheric ozone pollution ... Atmospheric CO2 enrichment

  5. Land use change and anthropogenic disturbance

  6. Alien species invasion A. Danin A. Danin Barry A. Rice

  7. 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

  8. Differential impact of global change on plant species Species  = increase  = decrease = inconsistent response 0 = no change  • Global change manipulation in a ‘natural’ grassland in California: • Atmospheric CO2 enrichment (C) • Climatic warming (W) • Rain (precipitation) addition (P) • Atmospheric nitrogen deposition (N) Modified from Zavaleta et al. 2003 Ecol. Monogr.

  9. Impact of global change on plant species: example from a semi-arid community under atmospheric CO2 enrichment a b 300 b 200 Aboveground biomass (g m-2) 25 100 Onobrychis crista-galli P = 0.009 20 0 280 440 600 440-280 CO2 concentration (ppm) 15 600-280 10 Change in aboveground biomass (g·m-2) A.s. P.f. 5 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. T.c. H.u. D.g. Br.d. M.t. S.c. R.s. R.p. P.cr. R.a. S.p. H.c. -5 Species Grünzweig & Körner. 2001. Oecologia. Grünzweig & Körner. 2001. Oikos

  10. 0.4 0.3 LWRa 0.2 0.1 0.0 280 440 600 CO2 concentration (ppm) • 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) • Allocation of carbon to symbionts and exudation Leaf weight ratio (LWRa = leaf DW / total aboveground DW) for Onobrychis crista-galli

  11. Water saving under atmospheric CO2 enrichment as indirect effect on plant performance and species composition 28 7 39 7 Low CO2 High CO2 Evapotranspiration Rain 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

  12. 1200 600000 P = 0.010 P = 0.001 800 400000 Seed production (no. m-2) 400 200000 0 0 280 440 600 280 440 600 CO2 concentration (ppm) CO2 concentration (ppm) A. Danin Seed production at elevated CO2 Onobrychis crista-galli Parentucellia flaviflora

  13. Competition between a semi-arid C4 pasture grass and an invasive C3 weed under atmospheric CO2 enrichment Cenchrus ciliaris introduced C4 pasture grass in semi-arid subtropical and tropical pastures of northern Australia Parthenium hysterophorus invasive C3 weed P.h.:C.c. = 1:1 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

  14. Invasive weeds under past and future atmospheric CO2 enrichment Increase in total biomass (%) Potential causes of increased growth under elevated CO2: Substantial belowground sinks contributing to largely stimulated plant growth → potential link between invasiveness and CO2 responsiveness Ziska. 2003. J. Exp. Bot.

  15. Hemiparasite performance under global change Phoenix & Press. 2005. Folia Geobot.

  16. 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)

  17. 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

  18. Skinner et al. 2000. Weed Sci.

  19. 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

  20. 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.

  21. Mediterranean islands

  22. Plant invasion on Mediterranean islands Human-dominatedhabitats Habitat Modified from Hulme et al. 2008 In: Tokarska-Guzik et al., Backhuys Publishers

  23. Impact of climate and land use on plant invasions Barry A. Rice Oxalis pes-caprae invasion on the island of Crete (Greece) Initial bulbil biomass Agricultural sites colonized by Oxalis pes-caprae Ross et al. 2008 Persp. Plant Ecol. Evol. Syst.

  24. Juniperus oxycedrus Quercus coccifera Quercus ilex Ailanthus altissima Model output on the effect of disturbance frequency on native and invasive species on the island of Lesbos (Greece) Gritti et al. 2006. J. Biogeogr.

  25. 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.

  26. Theory of alien invasions can suggest causes for successful invasive weeds Invasive species Combination of a) and b) Keane & Crawley. 2002 Blumenthal. 2005. Science a) Increased resource availability b) Enemy release Davis. 2000. J. Ecol.

  27. 4. Conclusions: Weed success and invasion at different spatial scales in arid and semi-arid regions under future changed conditions

  28. 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

  29. 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

  30. Thank you!

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