Impacts of climate change on forests in different climatic zones and their implications on sustainable development

Abstract

Atmospheric and meteorological data collected during the last few decades show clear evidence thatglobal climate is undergoing a long-term change. Increasing atmospheric concentrations of greenhousegases (i.e. CO" CH4, NO, and CFCs) and the consequent warming of the atmosphere are clearfeatures of' long-term climate change. Because of their long life span, these changes in climate areIikely to influence the functioning and productivity offorest ecosystems. The objective of this reviewis to predict the impacts of climate change on forests on the basis of experimental results on key plantphysiological and ecological processes.

There is clear experimental evidence that increasing atmospheric CO2 (C ) increases photosynthesisand biomass production of forests. However, the magnitude of growth shmulation is likely to varywith temperature. The highest increases in productivity are expected to occur in the cooler and moistclimatic zones while the productivity increases would be lowest or absent in the warmer and drierzones. It is highly probable that the species composition offorests in all climatic zones would changebecause of the differential response of different plants species to increases in Ca and temperature.There is clear evidence that the underlying physiology of all plant species become relatively droughttolerant with increasing C . Hence, there is a possibility that in areas which are not deforested due tohuman population pressure, the existing forests would spread beyond their present boundaries withlowland evergreen forests extending to relatively drier, sub-humid climates and dryland deciduousforests extending to relatively semi-arid climates.

Climate change induced changes in forests will definitely trigger changes in soil and in the complexnetwork of organisms that inhabit forests. While the inputs of carbon and nutrients to the soil throughIitter fall and root exudates are Iikely to increase with increasing Ca' soil organic matter decompositionwould also increase with increasing soil temperatures. Photosynthesis in a future high CO, environmentwill produce plant tissues with higher carbohydrates, but lower nitrogen. This will affect tlie populationsof organisms which feed on plants. Therefore, the climate change induced changes in forests couldcause wide ranging and complex secondary and tertiary effects on the whole forest ecosystem.

It is well-established that management of forest resources is a vital component of sustainabledevelopment. Therefore, understanding and identifying the impacts of climate change on forestecosystems would be essential in formulating rational forest management strategies to achieve longtermsustainable development.