DOI: 10.5061/dryad.264j9
title: Data from: The determinants of tropical forest deciduousness: disentangling the effects of rainfall and geology in central Africa

description: Understanding the environmental determinants of forests deciduousness i.e.
 proportion of deciduous trees in a forest stand, is of great importance
 when predicting the impact of ongoing global climate change on forests. In
 this study, we examine (i) how forest deciduousness varies in relation to
 rainfall and geology, and (ii) whether the influence of geology on
 deciduousness could be related to differences in soil fertility and water
 content between geological substrates. The study was conducted in mixed
 moist semi-deciduous forests in the northern part of the Congo basin. We
 modelled the response of forest deciduousness to the severity of the dry
 season across four contrasting geological substrates (sandstone, alluvium,
 metamorphic and basic rocks). For this, we combined information on forest
 composition at genus level based on commercial forest inventories (62 624
 0.5 ha plots scattered over 6 million of ha), leaf habit, and rainfall and
 geological maps. We further examined whether substrates differ in soil
 fertility and water-holding capacity using soil data from 37 pits in an
 area that was, at the time, relatively unexplored. Forest deciduousness
 increased with the severity of the dry season, and this increase strongly
 varied with the geological substrate. Geology was found to be three times
 more important than the rainfall regime in explaining the total variation
 in deciduousness. The four substrates differed in soil properties, with
 higher fertility and water-holding capacity on metamorphic and basic rocks
 than on sandstone and alluvium. The increase in forest deciduousness was
 stronger on the substrates that formed resource-rich clay soils
 (metamorphic and basic rocks) than on substrates that formed resource-poor
 sandy soils (sandstone and alluvium). Synthesis. We found evidence that
 tropical forest deciduousness is the result of both the competitive
 advantage of deciduous species in climates with high rainfall seasonality,
 and the persistence of evergreen species on resource-poor soils. Our
 findings offer a clear illustration of well-known theoretical leaf carbon
 economy models, explaining the patterns in the dominance of evergreen
 versus deciduous species. And, this large-scale assessment of the
 interaction between climate and geology in determining forest
 deciduousness may help to improve future predictions of vegetation
 distribution under climate change scenarios. In central Africa, forest is
 likely to respond differently to variation in rainfall and/or
 evapotranspiration depending on the geological substrate.
description: Data_OuedraogoEtAl2016_JEcolWe provide a zip file containing three txt files used in the analyses presented in the article showing the alteration of the relationship between forest deciduousness and climate with the geological substrate. The species_trait.txt file contains the species x traits data (767 species, 2 traits). The plot_gen_trait.txt file contains the plot x genera x traits data (62 624 plots, 247 genera). The plot.txt file contains plot location, area, geological substrate, HWSD soil map unit, most common FAO soil type with its proportion in the soil map unit, monthly rainfall, annual rainfall, monthly potential evapotranspiration, annual potential evapotranspiration, and maximum climatological water deficit.