COS 11-1
Effects of annual and inter-annual environmental variability on soil fungi associated with an old-growth, temperate hardwood forest
Seasonal and inter-annual variability in temperature and precipitation play an important role in regulating nutrient cycling, plant growth, and soil microbial community structure in forests. Changes in precipitation and temperature could affect the distribution and relative abundance of fungal species and the processes they mediate; however, we still know relatively little about how environmental variability will affect fungal community dynamics. Yet a greater understanding of inter-annual environmental variation is necessary to better predict the effects of changing climate on forest soil fungi. In this study I hypothesized that 1) annual variability in soil moisture and temperature would affect the abundance and distribution of soil fungi and that 2) inter-annual variability in snow cover would alter species distributions between years and affect species relations with soil chemistry. I collected soil cores every month for three years from permanent plots established in an old-growth hardwood forest in Northeastern Ohio. Soil was subdivided into three depths and used to measure chemistry and determine fungal species distribution using terminal restriction fragment length polymorphism (TRFLP) coupled to a site specific database of fungal sequences. Soil temperate, moisture and soil cover were monitored continuously during the three years of sampling.
Results/Conclusions
Species richness ranged from 1-19 per core, with a mean of 10-11 species. I found contrasting patterns for diversity: during the first year fungal richness and diversity were significantly affected by season, while evenness was significantly affected by plot; however, soil depth had no effect. During the third year neither season nor plot significantly affected any fungal diversity measures, but evenness, richness and diversity were all significantly affected by depth. These annual differences were associated with variation in late winter snow cover. Fungal communities significantly varied by plot, season and depth and differences were consistent between years (2-way PERMANOVA, P<0.01). However, indicator species analysis suggested that individual fungal species were not consistent in their seasonality or in their preference for certain soil depths between years. Although many fungi were correlated with soil chemistry (e.g. phosphorous), correlations also changed between sample years. These results suggest that fungal communities change between seasons and years, but the occurrence of individual species is not easily predictable. Rather community composition may reflect the idiosyncratic behavior of the individual species within the community pool and how resource requirements and life history strategy coincide with resource availability to influence species occurrence at any time point.