Replacing native forests with tree plantations is harming the soil at a microbial level by having an impact on soil fertility and the health of the planet.

This is one of the conclusions of North-West University (NWU) academic Prof Olubukola Oluranti Babalola – who along with Dr Adenike Eunice Amoo – recently conducted ground-breaking research to investigate the impact of land-use change on soil bacterial communities and characteristics.

“Soil microbial communities are an important part of ecosystems and possess the capability to improve ecosystem services. However, several aspects of the ecology of forest soil bacterial communities are still unknown,” says Prof Babalola.

Evidence from their study titled “Impact of land use on bacterial diversity and community structure in temperate pine and indigenous forest soils,” indicates that microbial communities and multifunctionality in forest ecosystems are linked, and land-use change affects the structure of soil microbes and consequently their functioning.

The study used high-throughput sequencing to ascertain the bacterial diversity, and canonical correspondence analysis to determine relationships between the bacterial communities and environmental variables.

Human land use is to blame

Prof Babalola says the research indicates that the enormity of land use by humans has increased because of the ever-growing population.

“Anthropogenic disturbances lead to soil erosion, loss of soil fertility and fossil fuel usage, subsequently causing climate change.

“Globally, about 40% of lands have been converted into managed systems. Forest ecosystems are lavished with trees, and this feature differentiates them from other terrestrial biomes. They act as carbon sinks and mitigate climate change. Due to the increase in demand for timber, native forests have been converted into tree plantations,” she explains.

In a native forest, microbes facilitate approximately 90% of soil processes. However, the conversion of native forests to tree plantations has an impact on the structure and function of soil microbes.

“Soil microbes play essential roles in the productivity of forests, and the loss of diversity in soils has functional consequences, since microorganisms are facilitators of the majority of the biogeochemical cycles. The Earth’s biodiversity level is deteriorating, which has serious global effects because of the contribution of biodiversity to ecosystem functioning,” she warns.

According to Prof Babalola, the research revealed higher bacterial richness and diversity in native forests, indicating that land-use change strongly influences soil bacterial communities.

“Reduction in microbial diversity will diminish multiple ecosystem functions, having a negative impact on the provisioning of ecosystem services like soil fertility, regulation of the climate and the production of food by terrestrial ecosystems. If possible, the substitution of native forests with tree plantations should be avoided entirely. This is essential for ecosystem sustainability,” she concludes.

For further details, view Amoo, AE and Babalola OO. (2019). Impact of land use on bacterial diversity and community structure in temperate pine and indigenous forest soils. Diversity 11:217 here.

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