Variation in nutrient availability and plant species diversity across forband graminoid zones of a Northern New England high salt marsh

Plant zonation patterns across New England salt marshes have been investiga ted for years, but how nutrient availability differs between zones has rece ived little attention. We investigated how N availability, P availability, and plant N status varied across Juncus gerardii, Spartina patens, and mixe d forb zones of a Northern New England high salt marsh. We also investigate d relationships between several edaphic factors and community production an d diversity across the high marsh. P availability, soil salinity, and soil moisture were higher in the mixed forb zone than in the two graminoid zones . NH4+-N availability was highest in the J. gerardii zone, but NO3--N avail ability and mid season net N mineralization rates did not vary among zones. Plant tissue N concentrations were highest in the mixed forb zone and lowe st in the S. patens zone, reflecting plant physiologies more so than soil N availability. Community production was highest in the J. gerardii zone and was positively correlated with N availability and negatively correlated wi th soil moisture. Plant species diversity was highest in the mixed forb zon e and was positively correlated with P availability and soil salinity. Thus , nutrient availability, plant N status, and plant species diversity varied across zones of this high marsh. Further investigation is needed to ascert ain if soil nutrient availability influences or is a result of the producti on and diversity differences that exist between vegetation zones of New Eng land high salt marshes.