Influence of Climate Variation on Growth of Tropical Tree Species in Western Kenya
Eric T. David
Department of Forestry, Michigan State University, Natural Resources Building, 480 Wilson Road, Room 126, East Lansing, Michigan 48824-1222, USA.
Sophan Chhin *
Division of Forestry and Natural Resources, Davis College of Agriculture, Natural Resources and Design, West Virginia University, 322 Percival Hall, P.O.Box 6125, 26506-6125, USA.
David Skole
Department of Forestry, Michigan State University, Global Observatory of Ecosystem Services (GOES), 101 Manly Miles Building, 1405 S. Harrison Rd., East Lansing, Michigan 48823, USA.
*Author to whom correspondence should be addressed.
Abstract
Aims: Growth-climate relationships were examined in 7 tropical tree species growing in the Yala river basin of western Kenya: Acacia mearnsii, Cupressus lusitanica, Eucalyptus camaldulensis, Eucalyptus grandis, Eucalytus saligna, Mangifera indica, and Markhamia lutea.
Methodology: Standardized basal area increments were correlated with monthly and seasonal (3 month periods) climate variables (precipitation, mean temperature, Climate Moisture Index) obtained from nearby meteorological stations.
Results: A majority of the tree species (M. indica, C. lusitanica, E. camaldulensis, and E. saligna) showed positive correlations with monthly and seasonal precipitation and moisture index during periods of the long and short rainy seasons. This study also revealed significant correlations between monthly and seasonal temperature data and radial growth of M. indica, M. lutea and E. grandis. Growth of M. lutea was negatively affected by cool growing season conditions while M. indica and E. grandis experienced high temperature stress.
Conclusion: Associations between radial growth of tropical tree species and temperature are generally rare in warm tropical regions, and for some of the species examined in this study that are non-native (i.e., M. indica and E. grandis), strongly suggests that they may be growing outside the optimal temperature conditions of their native geographical range.
Keywords: Climate, dendrochronology, Kenya, precipitation, temperature, tropical ecosystems.