Climate change is already affecting the diversity and productivity of forests and trees on farms through its impact on growing seasons, pest and disease outbreaks and tree population size and distribution.

Source: Locatelli et al., 2010

Neil Palmer, CIAT

Extra facts

  • Climate change affects forests and their biodiversity by altering animal and plant reproduction, animal migration, growing season length, species distributions and population sizes and the frequency of pest and disease outbreaks (Root et al. 2003).
  • Climate change is projected to affect all aspects of biodiversity and ecosystem functioning in natural forests both directly (through temperature increases, precipitation changes, sea level changes and storm surges in coastal ecosystems) and indirectly (through changes to the intensity and frequency of wildfires and other disturbances) (Williams et al. 2008).
  • Tropical mountain humid forests are particularly vulnerable to shifts in temperature and precipitation. In tropical dry forests, changes in rainfall and temperature can affect vegetation productivity and plant survival and make them susceptible to fire. In tropical mangroves, the principal threat comes from sea level rise and its consequences on sediment dynamics, erosion and salinity (Locatelli et al. 2010).
  • Trees on farms and agroforestry systems can also be expected to undergo climate-related impacts on survival, ranges, growth rates, yields, pests and diseases and pollination (Thornton and Cramer 2012).
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Methods, caveats and issues

  • There is no information on climate responses for most tree species grown in agroforestry systems. The same is true for tree responses to elevated CO2.
  • Appropriate process-based models of agroforestry systems are yet to be developed. Experimental trials of agroforestry systems are difficult to implement and maintain in the field. Some experimental research is possible, and has been conducted to investigate the possible consequences of climate change during the early stages of establishment of agroforestry systems.
  • Modeling the changes in forest biodiversity in response to climate change presents some significant challenges. The data and models needed to project the extent and nature of future ecosystem changes and changes in the geographical distribution of species are incomplete—these effects can only be partially quantified (Thornton and Cramer 2012).
  • Models assume that biotic factors affecting ecosystems, such as pest and disease organisms, or pollinators, migrate at rates corresponding to shift in vegetation types.
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Sources

  • Thornton P, Cramer L, eds. 2012. Impacts of climate change on the agricultural and aquatic systems and natural resources within the CGIAR’s mandate. CCAFS Working Paper 23. Copenhagen: CGIAR Research Program on Climate Change, Agriculture and Food Security. (Available from http://cgspace.cgiar.org/handle/10568/21226)
  • Locatelli B, Brockhaus M, Buck A, Thompson I. 2010. Forests and adaptation to climate change: challenges and opportunities. In: Mery G, Katila P, Galloway G, Alfaro RI, Kanninen M, Lobovikov M, Varjo J, eds. Forests and Society: Responding to Global Drivers of Change. Vienna: IUFRO-WFSE. p. 21–42. (Available from http://www.iufro.org/science/special/wfse/forests-society-global-drivers/)
  • Root TL, Price JT, Hall KR, Schneider SH, Rosenzweig C, Pounds JA. 2003. Fingerprints of global warming on wild animals and plants. Nature 421:57-60.
  • Williams SE, Shoo LP, Isaac JL, Hoffmann AA, Langham G. 2008. Towards an integrated framework for assessing the vulnerability of species to climate change. PLoS Biology 6:2621–2626.
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