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LONG-TERM ECOLOGICAL RESEARCH ON SPRING-FEN COMMUNITIES AT THE ST. CROIX WATERSHED RESEARCH STATION, WASHINGTON COUNTY, MINNESOTA.
| 题名： | LONG-TERM ECOLOGICAL RESEARCH ON SPRING-FEN COMMUNITIES AT THE ST. CROIX WATERSHED RESEARCH STATION, WASHINGTON COUNTY, MINNESOTA. |
| 作者： | Janssens-Joannes-A; Noble-Mark-G; Main-Stephen-P; Haferman-Jonathan-L |
| 关键词： | Ecology-; Hydraulics-; Hydrology-; Monitoring-; Peat-; Plants-; Seasonal-surveys; Vegetation-; Washington-County-Minnesota; Water-table; Watersheds-; pH-value |
| 摘要： | The project involved intense monitoring of two permanent plots of spring-fen vegetation at the St. Croix Watershed Research Station, Washington County, Minnesota, during the growing seasons of 1994-1999. Plot C was covered by a thin layer of mineral sediment, deposited during the heavy rains of summer 1993. At each plot, the research measured the peat surface, water-table elevations, hydraulic heads, cover by open water, and litter cover. Researchers analyzed water samples for pH, specific conductance, and absorbance, took samples for diatom analysis, and conducted vascular-plant surveys during each survey. The bryophyte flora was surveyed in 1991 and again in 1994 and 1999. The vegetation cover was photographed seasonally and initially included stereographic air photos as baseline images. Very little unidirectional change can be observed on plot C. Comparisons of the recorded changes between the plots and among the results of the seasonal surveys suggest that only the seasonal amplitude of variation on plot C might have increased. After summer 1996 relative water tables and piezometer heads drop on both plots. The hydrological measurements suggest that both plots have become significantly drier, but the vegetation appears not to have responded yet, nor has the peat build-up stopped. |
| 总页数： | 1999/11. pp34 (5 Fig., 2 Tab., 5 Ref., 3 App.) |
| 报告类型： | 科技报告 |
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