Recent studies have highlighted specific traits of forest trees as regulators of ecosystem processes, including decomposition, nutrient cycling, and carbon storage. Many of those studies have focused specifically on the mycorrhizal association of dominate trees as a fundamental driver of biogeochemical cycling. However, environmental and abiotic factors related to climate, soil, and land-use are also considered master variables that control a diverse array of ecosystem dynamics. There is a clear need for studies that examine the relative influence of mycorrhizal tree types and environmental controls across natural gradients as a means to predict consequences of environmental change and altered biodiversity. We argue that the Adirondack Park (AP) of upstate NY is an ideal system for studying such relationships due to a relatively small number of overstory tree species, distinct climatic gradients, uniform geology, and well-documented land-use patterns. We began establishing permanent sampling plots in 4 distinct regions of AP that vary with respect to climate and tree communities, but have similar land-use history. At each site, 24 15-m radius plots (12 on south and 12 on north aspects) are centered on a dominant focal tree with the goal of varying mycorrhizal tree dominance from 0 to 100% ectomycorrhizal (ECM).
Plots established in southeastern AP, the driest region of AP, revealed that stand-level distributions of ECM vs Arbuscular Mycorrhizal (AM) tree types on both south and north aspects are relatively even, but that AM and ECM species relative dominance varied with aspect along with expected differences in soil temperature/moisture. When summing all stems over 2 cm DBH, our plot-level ECM dominance ranged from 20-90% basal area with focal trees evenly split between ECM and AM tree types. Despite aspect differences in ECM and AM communities, forest floor accumulation (mass) and soil inorganic nitrogen content at 10 cm depth followed hypothesized trends of decreasing inorganic nutrients and increased dependence on organic nutrient cycling as %ECM basal area increased (p<0.01). However, this relationship was not apparent at the 20 cm depth regardless of aspect and nitrogen pool differences between aspects. Thus far, we conclude that specific mycorrhizal distribution patterns are apparent across short distances and provide support for hypothesized patterns of carbon and nutrient cycling related to tree functional traits. We will present these results along with data from 3 additional sites that span a climatic and tree species gradient to further elucidate patterns and drivers.