Land use, soil microorganisms, organic carbon and biodiversity: putting the pieces together
We set out to study what biodiversity is, and how it can be influenced by human activities. To carry out this research we looked for two relatively closed natural small-island systems: one little-influenced by human settlement and another equivalent but heavily settled. In these two environments, two transects were created in 10 sub-ecosystems, from the sea to the mainland. We sought similar sub-ecosystems in both places. We selected a series of 8 points along the same gradient in the two environments, with two additional non-overlapping points, specific to “natural plus" or "natural minus". We studied soil microorganisms and arthropods to have a large number of cases (OTUs) available, also studying the microorganisms' phylogenetic status. We also compared biodiversity with soil organic carbon (SOC) content, using two SOC measurement systems, to understand biodiversity starting from its potential source of food (SOC). The results surprised us: the biodiversity indices are higher in the anthropized environment; the level of biodiversity depends more on chance and less to genetic exchanges in anthropized ecosystems, it depends on selection and it shows a higher phylogenetic signal in natural environment; the level of biodiversity of these microorganisms (OTUs) is linked to the quantity of organic carbon measured in the first 30 cm of soil with two different methods, Carbon Still Yeomans (650 g) and Walkey-Black (5 g). The following here forced line at the origin explains 85% of the variance: Where log = log 2. The concept of biodiversity merges with that of survival: the more species there are, the better they are organized among themselves in the process of food consumption (SOC utilization), and the better they will be able to transform the environment to survive and evolve with it. We wanted to identify the differences in soil biodiversity of natural and anthropogenic ecosystems, to offer evidence-providing tools to land managers to achieve more ecologically-efficient managing practices.