Predicting and understanding the effects of land use on soil bacterial communities over large scales

Bacteria contribute the largest proportion of the soil genetic pool, and along with other soil organisms are thought to be key drivers of various biogeochemical cycles. There is therefore widespread scientific interest in how bacterial biodiversity is affected by land use change and how this affects soil functionality and ecosystem services. From a policy perspective also, there is a need to provide relevant indicators of change in soils so as to establish target criteria to assess soil degradation and the efficacy of mitigation procedures. This talk will discuss results from over one hundred local land use transitions on soil biodiversity and soil properties, using datasets from both large scale soil biodiversity surveys such as the UK Countryside Survey, and more recent targeted sampling within the EU funded EcoFINDERS project and other UK initiatives. We firstly show that bacterial communities are a particularly sensitive component of soil biodiversity for use as indicators of change in soils. Secondly we illustrate that bacterial communities in bulk soils are strongly driven by soil parameters, and that this knowledge of broad biodiversity gradients from large scale surveys can be used to predict and explain change within local land use transitions. In particular we show that the magnitude of variation in bacterial biodiversity is related to the specific land use transition context, and also relates to the relative change in soil parameters such as pH and organic matter. Finally we will discuss the results in terms of specific bacterial indicators of change, and demonstrate that similar bacterial taxa can be indicators of either intensively managed or pristine soils depending upon the specific context of the land use transition with respect to the wider soil biodiversity physical-chemical gradient.