Fungal root endophyte in vitro growth traits in response to nitrogen enrichment in the Plum Island Ecosystems LTER, MA

Root endophytic fungi were isolated from Spartina alterniflora roots at the Plum Island Ecosystems Long Term Ecological Research (PIE LTER) site, where a long-term nitrogen addition experiment manipulates nutrient inputs. Experimental plots receive nitrogen in the form of nitrate, ammonium, or serve as ambient controls. This dataset represents a subset of culturable root endophytic fungi selected from a broader community survey to examine variation in growth traits and ecological memory. Isolates were categorized based on their field occurrence: generalists (present across all treatments), control-only, ammonium-associated, and nitrate-associated taxa. Fungal isolates were grown in vitro on media amended with high nitrate, high ammonium, or control conditions to assess responses to nitrogen environment. Growth was quantified by measuring colony area (mm²) from standardized fungal plugs using ImageJ at three time points. After two weeks, fungal biomass was harvested for each isolate. Together, these data quantify isolate-specific growth responses and potential legacy effects of field nitrogen conditions under controlled in vitro environments.