Quelle: Forstarchiv 80: 3, 76-89 (2009)
Autor(en): Barnes B V
Abstract: Uncertainty characterizes climate change and concomitant tree response at all landscape ecosystem scales. Tree response in a recognized time of rapid climate change and global warming provides one of the best terrestrial clues to understand ecosystem change. The landscape ecosystem approach provides a robust way of monitoring the individualized response of trees at multiple landscape scales. The climate-envelope modeling approach for the whole of eastern North america projects the future potential range of 130 native tree species. An average northward shift of 700 km is foreseen by the end of the 21st century. A second approach, based on forest inventory data of the united states, confirms this major northward and individualistic shift in the potential distribution of trees. It is generally agreed that this projected potential distribution of native trees will not be realized. The reasons include relatively slow migration rate, lack of suitable establishment sites, forest fragmentation, natural disturbance dysfunction and uncertainty, aggressive competition from non-native species, silvicultural activities, and genetic maladaptation. Community composition is expected to be markedly different than that of today, in part due to the decline of many native present-day species impacted by non-native insects and pathogens. Tree response is examined in four regions, southern Florida, southern appalachians, Great Lakes region, and mid-atlantic region. The future migration potential for upland oaks and red maple given todays conditions is problematic for oaks and bright for red maple. Given the multiple uncertainties of climate change and tree response, the use of ecological land classification, for monitoring and understanding tree migration at regional and local scales, is encouraged. The Canadian Forest service is in the forefront of analyzing and describing the expected effects of climate change on forests and in recommendations that advocating adaptive and risk management in the forest sector. Assisted migration of biota in a time of uncertainty should proceed with caution using an ecosystem approach.
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