Tropical forests threatened
TROPICAL forests in West Africa, with an already drier climate, undergo greater biodiversity loss and could support fewer species of plants and animals when confronted with further heat and drought.
This imperils not only iconic species, but is likely to have an impact on local livelihoods and the ability of forests to capture carbon, a new study led by the University of Oxford has found.
For the first time, researchers have demonstrated how climate impacts differ between wetter and drier tropical forests in West Africa, finding that drier forests are already at the limit of their adaptation, existing on the edge of a tipping point and at risk of losing further species, according to the university statement.
Until now, it has been thought that drier forests would already be more adapted to drought, and more able to cope with climate change. The biodiversity of wetter tropical forests, where rain is common year-round, did not appear to be impacted by the warming climate so far and even increased under drier conditions.
The researchers explain that this may be because these forests have greater reserves of moisture stored in their trunks and soils, which can be drawn upon to cope with dry periods.
“In sum, we demonstrate that tropical forests in West
Africa show changes in their facets of diversity partly due to a changing climate and partly to their dependence on intrinsic soil properties,” says the study, which was published in the journal Nature Communications yesterday.
“Drier forest communities that have experienced stronger decreases in water availability have undergone functional, taxonomic and phylogenetic diversity homogenisation.
“Such homogenisation process could have negative effects on the current functioning of such tropical ecosystems and therefore on their contribution to people’s livelihoods.”
Lead author Dr Jesus Aguirre, a researcher at the university’s Environmental Change Institute, said he hopes the research will help practitioners understand which parts of the forest run a greater risk of biodiversity loss and need greater protection efforts.
“Since drier tropical forests are at greater risk due to climate change they may also be less resilient to additional anthropogenic impacts, leading to further forest degradation.”
Drier tropical forests are home to a number of threatened plants, important for local livelihoods and human health including the afina, a hard, termite-resistant wood used in construction, and the limba, a prized timber species also used in traditional medicine to treat wounds, sores and malaria and which was used to make Gibson guitars in the 1950s.
The tropical forest canopy is one of the earth’s underexplored frontiers. University of Oxford scientists worked with over 30 Ghanaian researchers and students to collect detailed information on the leaves and wood of 299 trees from 94 distinct species over a period of six months.