Vegetation patterns and associated hydrogeochemical cycles in a calcareous sloping fen of southwestern Massachusetts
Calcareous wetlands are rare in New England due to the limited occurrence of limestone-rich bedrock. Because of their great floristic diversity and their support of numerous rare and uncommon plant species, these habitats are targeted for conservation. Little is known about the intricate workings of these ecosystems. This research contributes significantly to understanding the complex biogeochemical relationships that exist between the plant and soil systems in calcareous freshwater wetland environments as a whole.
A 3-year field study was initiated in May 1996, to collect data on soils, geochemistry, and hydrology along a 250-m-long transect. Monitoring was concentrated within the rooting zone. Field monitoring and water sampling were conducted biweekly across three growing seasons. Measurements were made for soil-water pH, conductivity, total iron, alkalinity and several dissolved metals. Strong seasonal patterns were observed for several parameters including calcium and iron. Seasonal changes in geochemistry were evaluated using Solmineq.88, a thermodynamic model.
In July 1997, soils were sampled adjacent to each replicate instrumentation cluster and standard analyses conducted. Significant differences were measured between the stations for pH, cation exchange capacity, exchangeable calcium, phosphorus, manganese, and biologically available iron.
A detailed vegetation analysis was completed in July 1997. High species richness and turnover were measured across the site. Ordination and cluster techniques were used to analyze the vegetation patterns and relate these to environmental site variables. The ordinations suggest that gradients in both soil chemistry (e.g., pH, exchangeable calcium, phosphorus, and iron) and geochemistry (e.g., pH and dissolved calcium) may have strong influences on the vegetation patterns observed in this study.
These research results will serve as a baseline for the geochemistry in the greater watershed region, representing a relatively undisturbed system. No fen studies currently exist (for any geographical region) that monitored soil and geochemical parameters throughout the growing season. This research demonstrates the importance of seasonal sampling to describe the cycles present in site biogeochemistry accurately, and it defines several geochemical parameters that strongly influence plant species occurrence and distribution within these environments. This detailed analysis provides valuable information for conservation managers seeking to identify areas for future conservation, preservation, or restoration efforts.
0481: Soil sciences