Forests perform vital ecosystem functions including storing carbon, cycling critical nutrients and fostering biodiversity, and many of these functions can be reduced following a disturbance. Most research into the impacts of disturbance on forest health investigate single disturbances. Here, we investigated the effects of three common disturbances experienced by temperate forests across the eastern U.S., canopy gaps, surface fire, and grazing by large herbivores (i.e., deer), on soil carbon content and bacterial and fungal communities in a long-term forest disturbance experiment in the Monongahela National Forest, WV. Previous research into aboveground responses to these disturbances determined that canopy gaps and fire promoted a more diverse canopy and herbaceous layer, but only when herbivores were excluded. It remains unknown whether these above-ground changes can have below-ground consequences for carbon storage and microbial community composition. To determine this, we used an established long-term field experiment that implements three eastern forest disturbances (canopy gaps, surface fire and herbivory). SOM and labile carbon pools were quantified, and fungal and bacterial abundance and diversity were examined using the ITS region and 16S rRNA genes, respectively.
Results/Conclusions
Across all treatments, SOM content was approximately 4 times higher in the organic horizon than mineral horizon (F = 1448.02, p < 0.01), but did not differ significantly among treatments within horizons. Labile carbon was significantly higher in the organic horizon and mineral horizon control than in the other mineral horizon treatments (F = 83.48, p < 0.01). Bacterial abundance was significantly higher in the organic horizon (F = 17.45, p < 0.01), while fungal abundance did not differ between horizons or across treatments. Bacterial α-diversity was higher in the mineral horizon than in the organic horizon (F = 7.00, p < 0.01), but did not differ between treatments within horizons. Fungal α-diversity was significantly higher in the organic horizon than in the mineral horizon (F = 13.29, p < 0.01). Bacterial and fungal β-diversity did not differ by horizon or treatment. These findings suggest organic horizon carbon pools may recover from disturbances more quickly than mineral horizon pools. Unlike previous above-ground findings, herbivory does not appear to compound the SOM losses observed after fire or canopy gap creation. Differences in bacterial and fungal communities between horizons may be due to differences in SOM.