Soil bacteria/fungi

Increased UV-B may have an impact on soil bacteria and fungi (together termed “microbes”) in several ways.  The main effects include changes in biomass, activity, carbon to nitrogen ratios of microbial species, as well as a potential shift in the composition of the microbial community (which species are present and their relative abundances).

Most studies on this topic agree that increased UV-B will have a damaging effect on microbial biomass as well as their activity, at least in the surface or top few cm of soil.  This is likely to bring several consequences to nutrient cycling, as bacteria and fungi drive the process of decomposition. Essentially, microbes consume the nutrients (such as nitrogen and carbon) that plants and algae create through photosynthesis and return them to the soil and atmosphere in forms that plants can then re-use (eg. nutrients in the soil, or CO2 in the atmosphere).

That said, if there is a decrease in microbial biomass (or the quantity of microbes) to drive this process, less of the nutrients will be recycled back into ecosystems and available to plants.

Another effect increased UV-B may have on microbial processes is that it may alter the structure of these communities by having a greater effect on one type of microbe relative to another.  Bacteria and fungi play similar roles as far as ecosystem functioning, but differ slightly in what they take in (namely, the relative amounts of carbon and nitrogen they take in versus fix back into the system, or carbon:nitrogen ratios). If one of these groups is affected to a greater or lesser extend as a result of increased radiation, the carbon and nitrogen cycles will in turn be altered.


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