Title
Tropical monodominant forest resilience to climate change in Central Africa: A Gilbertiodendron dewevrei forest pollen record over the past 2700 years
Author(s)
Tovar, C.;Harris, D. J.;Breman, E.;Brncic, T.;Willis, K. J.
Published
2019
Publisher
Journal of Vegetation Science
Abstract
Question The existence of monodominant forest in highly diverse tropical rainforest has been the subject of much debate. One hypothesis suggests that the combination of advantageous traits and long periods of low disturbance is key for this forest persistence. Here we ask whether there is evidence for the long-term presence of monodominant Gilbertiodendron forest in the absence of fire and climate change. Location Republic of Congo. Methods We extracted fossil pollen and macro-charcoal from a sediment sequence collected in present-day monodominant Gilbertiodendron forest stand that spans the last 2700 years. Climatic changes were inferred using other published palaeoecological records from Central Africa. We also looked at Gilbertiodendron dewevrei's present-day ecological tolerances. Results Gilbertiodendron pollen was found in every sample covering the last 2700 years in similar percentages to present-day soil surface samples. In addition, no statistically significant change in pollen composition was found during this time despite wetter and drier vegetation changes documented in nearby mixed-forest cores over the same time period. No evidence of fire was found for a period of 2400 years. Only minimal burning occurred over the last 300 years in this monodominant stand. The analysis of ecological tolerances shows G. dewevrei has a broad niche for precipitation (1300 to 2460 mm). Conclusions Our pollen record is the first to describe the long-term ecological history of an African monodominant forest. Our results show this monodominant stand existed over the past 2700 years mostly in the absence of fire, providing support for the low disturbance hypothesis as an explanation for monodominance persistence. However, the persistence of the monodominant forest at this site occurs despite evidence for climatic fluctuations in the immediate region. This combined with the broad tolerance of water requirements of the species suggests a potential resilience to future climate variability. However, additional pollen records from a wider area are needed to confirm this. This article is protected by copyright. All rights reserved.
Keywords
Central African rainforest;fossil pollen;Gilbertiodendron, monodominant forest;late Holocene;palaeofires;past climate change;resilience;vegetation history
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