Keynote Presentations from the 2nd AVEC International Summer School, Peyresq, 18-30 September 2005

Speaker: Claus Beier
claus.beier<at>risoe.dk
Risø National Laboratory, Biosystems Department, Ecosystems Programme, Frederiksborgvej 399, 4000 Roskilde, Denmark

Title of the talk: Vulnerability assessment for European shrublands to climate change (pdf: 4,4MB)

Summary of the talk by Susann Wilhelm: Students´ summary (pdf)

Abstract

Vulnerability of European shrublands to climate change

Current predictions indicate that, unless greenhouse gas emissions are significantly curtailed, atmospheric CO₂ concentrations will double during the present century inducing an additional 1.4 to 5.8°C increase in mean global temperature, alterations in global and regional precipitation patterns, and increase the frequency and magnitude of severe weather events (e.g. droughts and floods). Such changes will have strong effects on the terrestrial ecosystems as CO₂, temperature and water are main drivers in ecosystem processes. In particular natural and seminatural ecosystems, e.g. shrublands, that are subject to no or very low management activities may be vulnerable to these changes.

In order to understand how climate change will affect European shrublands, the EU funded projects CLIMOOR and VULCAN conducted manipulation experiments with warming and drought at 6 shrubland ecosystems in DK, UK, NL, ES, IT and HU in a unique experimental design combining field scale experiments and studies along climatic gradients.

Various ecosystem processes may be affected to a different extent and balances between ecosystem processes as well as between ecosystems may shift and lead to major unpredicted changes. The results show that that warming affects carbon and nitrogen cycles and may impact on water quality through increased nitrogen leaching where N deposition is high. They further suggest that C and N cycles respond asymmetrically to warming, which may lead to progressive nitrogen limitation and thereby acclimation in plant production. In many temperate zones this acclimation will likely be delayed due to elevated N deposition. On the longer term ecosystem functioning and biodiversity may be affected because of observed shifts in species composition with changes in recruitment identified as a major mechanism for change in the Mediterranean area. Based on the experiments and a survey of main stressors and drivers in the vulnerability of European shrubland ecosystems, a regional vulnerability assessment for shrubland ecosystems were conducted.

Climate change is not a single factor problem. Recent results from an ecosystem experiment including several climate change factors have demonstrated, that the strong interactions among the climatic factors make predictions of the overall climatic effects difficult and request studies involving all factors (Beier 2004). Future climate change experiments must include combinations of the major impact factors and must employ methods that are realistic. In recent years several studies have been initiated to study climate change effects by combining the CO₂ dosing FACE technique with experimental warming and precipitation change, e.g. the Danish CLIMAITE experiment (www.climaite.dk).

Recommended background literature on this presentation:

• Beier C, Emmett B, Gundersen P, Tietema A, Peñuelas J, Estiarte M, Gordon C, Gorissen A, Llorens L, Roda F, Williams D (2004) Novel approaches to study climate change effects on terrestrial ecosystems in the field: Drought and passive nighttime warming. Ecosystems, 7:583-597. doi:10.1007/s10021-004-0178-8.


• Peñuelas J, Gordon C, Llorens L, Nielsen T, Tietema A, Beier C, Bruna P, Emmett B, Estiarte M, Gorissen A (2004) Nonintrusive field experiments show different plant responses to warming and drought among sites, seasons, and species in a North–South European gradient. Ecosystems, 7:598-612. doi:10.1007/s10021-004-0179-7.


• Emmett BA, Beier C, Estiarte M, Tietema A, Kristensen HL, Williams D, Peñuelas J, Schmidt I, Sowerby A, (2004) The response of soil processes to climate change: Results from manipulation studies of shrublands across an environmental gradient. Ecosystems, 7:625-637. doi:10.1007/s10021-004-0220-x.


• Schmidt IK, Tietema A, Williams D, Gundersen P, Beier C, Emmett BA, Estiarte M (2004) Soil solution chemistry and element fluxes in three European heathlands and their responses to warming and drought. Ecosystems, 7:638-649. doi:10.1007/s10021-004-0217-5.


• Wessel WW, Tietema A, Beier C, Emmett BA, Peñuelas J, Riis–Nielsen T (2004) A qualitative ecosystem assessment for different shrublands in western Europe under impact of climate change. Ecosystems, 7:662-671. doi:10.1007/s10021-004-0219-3.

AVEC is a EU FP5 Concerted Action No. EVK2-CT-2001-20010

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