Plant community development and peat stratigraphy in forested fens in response to ground-water flow systems

Abstract

The objective of this study was to examine plant community development and peat stratigraphy in the context of ground-water flow systems for five forested peatlands in central New York State for which extensive vegetation, surface hydrology, and water chemistry analyses has been performed. Peatland development trends, from the initial period of peat accumulation to the present, were explored using peat stratigraphy, analysis of ground-water flow systems and evidence from existing vegetation. Detailed analyses, including the construction of numerical ground-water models were performed for one of the five sites to examine the process of bog development within what was once a highly calcareous fen and to examine the impacts of agricultural drainage on peatland ground-water flow. Peat stratigraphy analysis indicated two pathways of peatland development: infilling of shallow lakes and peat accumulation on ground-water seeps. Lake-infill peatlands were characterized by a sequence of limnic peat→ bryophyte-sedge peat→hemic-fibric sedge peat→sapric wood peat (orSphagnum peat). Analysis of ground-water flow systems indicated that four of the peatlands were characterized by mineral-rich ground-water discharge along peatland margins, with lateral flow through the peatlands towards drainage features. The fifth peatland was characterized by a more complex ground-water flow system with a weakly minerotrophic water-table mound driving shallow ground-water recharge flow. The water-table mound has been reduced in extent by agricultural drainage and demonstrates seasonal fluctuations in hydraulic head and areal extent.