Importance of regional climates for plant species distribution patterns in moist Afromontane forest
Article first published online: 27 SEP 2012
© 2012 International Association for Vegetation Science
Journal of Vegetation Science
Volume 24, Issue 3, pages 553–568, May 2013
How to Cite
Schmitt, C. B., Senbeta, F., Woldemariam, T., Rudner, M., Denich, M. (2013), Importance of regional climates for plant species distribution patterns in moist Afromontane forest. Journal of Vegetation Science, 24: 553–568. doi: 10.1111/j.1654-1103.2012.01477.x
- Issue published online: 2 APR 2013
- Article first published online: 27 SEP 2012
- Manuscript Accepted: 1 AUG 2012
- Manuscript Received: 28 FEB 2012
- German Federal Ministry for Education and Research. Grant Number: 01 LM 0201 A1
- Bioclimatic variables;
- Floristic diversity;
- Multivariate statistics;
- Rain forest;
How are plant species distribution patterns in tropical montane forest linked to altitude, regional climate and geographic location? Which climatic variables are most important in explaining variations in floristic diversity? What are potential effects of climate change on species diversity?
Vegetation surveys were conducted in 180 study plots distributed across five moist montane forest areas in southwest and southeast Ethiopia (1000–2300 m a.s.l.). Temperature and precipitation data, as well as bioclimatic variables, were derived for each study plot from the WorldClim global climate data set. Species and climate data were analysed with direct and indirect ordination techniques and multivariate regression trees (MRT).
Each of the sampled forest areas showed a distinct species composition and was governed by a particular regional temperature and precipitation pattern related to the topographic variability of the Ethiopian highlands. Hence, a general altitudinal cut-off level for different forest types applicable in all five moist montane forest areas could not be identified. The most important bioclimatic variable in determining species distribution patterns was the amount of precipitation after the dry season (i.e. precipitation in the warmest quarter), followed by minimum temperature in the coldest month. At a lower hierarchical level, temperature and precipitation seasonality were also identified as significant discriminating variables. Generally, in areas with high precipitation during the warmest quarter (≥288 mm) and low minimum temperature in the coldest month (<10.9 °C), the number of Afromontane species was highest and that of Guineo–Congolian species lowest.
The altitudinal effect on species diversity in the Ethiopian moist montane forests is strongly modified by regional differences in precipitation and temperature regime. The predicted increase in temperature for the Ethiopian highlands due to climate change is likely to affect the distribution of the endemic Afromontane species. Furthermore, the study highlights the need for systematic on-the-ground measurements of climate variables in tropical montane areas in order to understand the current climate regime and as a basis for modelling future changes.