Evidence of thermophilization in Afromontane forests

Area of Science:

• Ecology
• Climate Change Biology
• Tropical Forest Ecology

Background:

• Thermophilization, a shift in species composition towards warmer-adapted species, is documented in temperate and Neotropical regions.
• Its occurrence in tropical forests, particularly in Africa with its unique biogeographic history and lower tree diversity, remains uncertain.

Purpose of the Study:

• To investigate the phenomenon of thermophilization in African tropical tree communities.
• To determine if equatorial African forests exhibit directional changes in species composition due to climate warming.

Main Methods:

• Analysis of re-census data from 17 forest plots across three mountain regions in Africa (Kigezi, Virunga, Udzungwa).
• Quantification of thermophilization rates using changes in species-associated temperature optima over time.

Main Results:

• Consistent evidence of thermophilization was found in African tree communities, with varying rates across the studied mountain ranges.
• Recruitment and mortality were identified as key drivers of thermophilization in these African forests, differing from patterns observed elsewhere.
• The studied forests currently function as carbon sinks, but the long-term implications of ongoing thermophilization are unknown.

Conclusions:

• Tropical tree communities in equatorial Africa are undergoing thermophilization, indicating a widespread response to climate change.
• The distinct drivers (recruitment and mortality) in African forests highlight regional differences in community responses to warming.
• Further research is needed to understand the future impact of thermophilization on the carbon sequestration capacity of these vital ecosystems.