Alpine Plant Communities of the White Mountains of New Hampshire: Aboveground Plant Diversity and Abundance Correlated to Belowground Factors

Alpine plant communities are fragile complex systems that may be threatened by climate change. Patterns of climate-driven soil warming are shown to have lasting effects on ecosystem nutrient cycles, alpine plant phenology, and belowground soil biotic activity. There are concerns in the alpine mycorrhizal research community as to how belowground fungal biomass will react to climate-driven soil warming. To address these concerns I asked in this study what are the correlations between belowground factors such as collective ectomycorrhizal (EcM) and ericoid mycorrhizal (ErM) percent colonization, pH, and soil depth to bedrock and aboveground plant diversity and richness. In 2018, on Mount Moosilauke, the southernmost peak in the White Mountain National Forest, I resampled 71m² plots along five transects initially established in 1993 and resampled in 2015. In each plot both vascular and non-vascular plant species richness, bare soil, exposed rock, and dead organic matter were assessed via percent cover and soil depth was measured. Soil was extracted (organic and mineral material) in nine plots per transect for pH testing and EcM/ErM analysis. The most significant increase in species richness, which was found in the Western fellfield community may indicate a shift in composition. The most significant negative relationship was between soil depth and species richness, and the most significant positive relationship was between soil pH and EcM/ErM colonization in the Southeast heath (T3) community. Soil pH, especially when associated with long-term acidification from atmospheric nitrogen deposition, can be a driver for reducing EcM/ErM diversity and richness in Northern temperate and boreal forest ecosystems. Given these relationships, one could assert that a combination of continued nitrogen deposition will drive the pH levels in alpine plant communities even lower and subsequently drive EcM/ErM diversity down leaving an opportunity for the more acidophilic mycorrhizae and their specialist conifer partners perhaps providing a mechanism for tree line encroachment into the alpine. The effects of climate warming and ongoing nitrogen deposition on plant productivity, phenology, and composition are of great concern to the alpine research community. More research is needed in these areas to help guide future conservation needs.