Periodic Reporting for period 1 - Terra-Micro-Carbo (Effect of land use induced shifts in soil microbial diversity and function on carbon cycling in soil)
Reporting period: 2015-07-14 to 2017-07-13
Overall objective of the project was to discern the effects of land use on soil microbial diversity and function, specifically addressing whether differences in communities lead to differences in soil C storage. The novelty of this research project was that it aimed to provide direct evidence to prove diversity-function linkages and gain mechanistic understanding of the physiological responses of soil microbial communities to land use change. The question we addressed were:
Q1: What is the effect of land use on soil microbial taxonomic and functional diversity in differing soil types? What factors are driving this shift?
Q2: Does this shift have implications for soil carbon cycling? Do certain microbial functional groups have a greater capacity for soil carbon storage?
Soils collected from across Britain were used for a landscape scale assessment of microbial functional traits that were then linked to soil C. A subset of 3 sites with a land use contrast in each was used in a small-scale experiment aimed at examining the temporal trends of microbial functional traits. Results from these experiments are quite novel and will be published in a highly-reputed journal very soon. We discern two distinct pH-related mechanisms of soil carbon storage and highlight that the response of these mechanistic indicators is shaped by the environmental context. Land use intensification in low pH soils that increases soil pH above a threshold value (~ 6.2) leads to loss of carbon due to increased microbial degradation as a result of lower acid retardation of plant organic matter decomposition. On the contrary, the loss of carbon through intensification in high pH soils was linked to decreased microbial biomass and reduced microbial growth efficiency. This was in turn linked to tradeoffs with stress alleviation and resource acquisition. We conclude that more extensive land management practices at higher soil pH have greater potential for soil carbon storage through increased microbial metabolic efficiency, whereas in organic acidic soils abiotic factors exert a greater influence.