Effects of prescribed burning and thinning on composition and function of the ectomycorrhizal fungal community in an oak woodland
North Mississippi uplands were historically maintained as open oak or oak-pine woodlands through frequent fire. After a period of fire suppression beginning in the 1920s led to a closed canopy, thinning and prescribed fire are now being used to create suitable habitat for fire-dependent plant and animal species. A key question is whether and how rapidly different biotic communities and their functions are responding to such restoration efforts. Because these treatments alter the abiotic environment as well as available host plants, they are expected to alter the ectomycorrhizal (ECM) fungal community as well.
We studied ECM fungi at three treatment sites that have been burned three times since the 1950s, most recently in 2010 and 2012, along with three paired control sites. Soil cores were taken from each treatment site, and molecular methods were used to identify the ECM fungi. To investigate functional effects of treatments on ECM fungi, soil from a nearby wildfire site, an unthinned prescribed burn site, and an untreated control as well as dead woody debris from the untreated and the wildfire sites were inserted into belowground plots, and potential activities of N-acetyl-glucosaminidase, laccase, and peroxidase were assayed on ECM root tips colonizing those plots.
As in a 2009 community survey at the same sites, site was more important than restoration treatment in explaining EMF abundance and species composition. Enzymatic activities of ECM fungi varied among substrate types, suggesting that the functions of ECM fungi may be able to shift in response to restoration treatments. Although research on the herbaceous plant and herpetofaunal communities present at the sites have found significant differences between treatment and control sites, the limited dispersal capabilities and short-lived spore bank of ectomycorrhizal fungi may entail a longer timeframe for restoration treatments to create a noticeable community shift.