PS 43-152 - Effects of precipitation anomalies on fruiting body production in mycotrophic and saprotrophic fungi in northern Spain: Analysis of a 27 year data set

Abstract: Natural-growing mushrooms (fungal fruiting bodies [FFB]) have been harvested for food and commerce in Soria, Spain for generations, and now also offer promise of a burgeoning myco-tourism industry in the economically-depressed region. Additionally, fungi play important ecological roles in breaking down decaying organic material (saprotrophic fungi) and the synergistic interactions with trees (mycotrophic fungi). Climate change is altering environments, raising questions about the effects on fungal communities and ecosystems, and future sustainability of mushroom harvests. FFB production is driven by precipitation patterns in many fungal species. In this study, we address how changes in precipitation patterns in Soria affect the annual abundance, total annual weight, and mean weight of FFBs. We investigate effects of precipitation anomalies on two functional groups: mycotrophic and saprotrophic fungi.

The study site is Pinar Grande, a managed pine forest in Central Spain. Eighteen 5m x 35m study plots were established and FFBs have been surveyed in each plot weekly between September-November from 1995- present. During each survey, FFBs were collected, identified, counted, and weighed. Monthly precipitation data from July-October were constructed from an ensemble of regional climate models. Relationships between FFB production and precipitation anomalies were assessed using linear models with AIC-based model selection and model averaging.

Over the 27-year study, 198 fungus species and species groups were collected in the study plots. An average of 1,480 mycotrophic and 1,807 saprotrophic FFBs were collected annually. Annual abundance and total annual weight of mycotrophic FFB were reduced in years with abnormally dry periods in July and September, while total annual weights of saprotrophic FFBs were reduced in years with abnormally dry July’s. The mean weights per saprotrophic FFB were lower in years with abnormally dry Augusts, while mean weights of mycotrophic FFB were lower in years with dry Augusts and Septembers. We found little evidence for non-additive effects of precipitation anomalies across multiple months.

Precipitation in July, September, and to a lesser extent August, were primary drivers of FFB production in this study, revealing similar environmental forcing of mycotrophic and saprotrophic fungi. There was little evidence that duration of precipitation anomalies beyond one month had emergent effects on FFB production. Precipitation in Spain is predicted to decline by 4-5% over the next century, suggesting that sustainability of FFB in central Spain may be strained in coming decades. However, our study highlights that the timing of dry periods is critical to the effects on FFB production.