DOI: 10.5063/aa/duc_merp.17.13
title: Marsh Ecology Research Program (MERP): Marsh evaporation pan data (1981-1989)

description: The Marsh Ecology Research Program (MERP) was a long-term interdisciplinary study on the ecology of prairie wetlands. A scientific team from a variety of disciplines (hydrology, plant ecology, invertebrate ecology, vertebrate ecology, nutrient dynamics, marsh management) was assembled to design and oversee a long-term experiment on the effects of water-level manipulation on northern prairie wetlands. Ten years of fieldwork (1980 -1989), combining a routine long-term monitoring program and a series of short-term studies, generated a wealth of new and diverse information on the ecology and function of prairie wetlands (Murkin, Batt, Caldwell, Kadlec and van der Valk, 2000). This data set includes evaporation pan data, from pans placed within the cells in different cover types, from 1981-1989. The impacts of annual variations in local weather conditions on hydrology, physical-chemical conditions in the water and sediments, and many biological processes are well known. Proximity to large bodies of water (e.g. Lake Manitoba) creates local ‘lake effects’ weather. Similarly, summer thunderstorms often are very spotty in distribution. Consequently, on site measurements of standard meteorological characteristics were very important to the Marsh Ecology Research Program (MERP). The objectives of the measurements described in this section were: 1) to provide general background data on local weather and 2) to provide data for use in computing water budgets (Kadlec, 1989). Because of the importance of hydrologic phenomena to nutrient import and export, local measures or estimates of precipitation and evapotranspiration were vital. Precipitation is reasonably well measured by standard rain gauges, which have the added advantage of being widely comparable to other data sets and studies. Evapotranspiration (ET) is less easily estimated. Therefore, several approaches were chosen: 1) standard class A evaporation pans, 2) evaporation pans (class A) installed in the marsh, and 3) estimation of ET by a modified Penman equation (Eagleson, 1970), utilizing data on temperature, wind, solar radiation, and relative humidity. Thus, 2 standard weather stations and 1 special station for wind, radiation and humidity data were installed. Two standard stations were used to better approximate average weather conditions over the entire study area (Kadlec, 1989). Although most data were recorded daily, only monthly averages were required for integration with most other data sets. This had the advantage that short term measurement errors tend to average out, giving more reliable data on the time scale of interest. Note: the MERP weather data (including precipitation, temperature, wind and class A evaporations at weather stations) is contained within a separate data package on the KNB. For further information on the Marsh Ecology Research Program (MERP), please visit: http://www.ducks.ca/conserve/research/projects/merp/index.html References: Eagleson, P.S. 1970. Dynamic hydrology. McGraw-Hill, New York, NY. 462pp Kadlec, J.A. 1989. Annual climatic factors. In: Marsh Ecology Research Program: Long-term Monitoring Procedures Manual. (Eds.) E.J. Murkin and H.R. Murkin, pp. 4-5. Manitoba, Canada: Delta Waterfowl and Wetlands Research Station. Murkin, H.R., B.D.J. Batt, P.J. Caldwell, J.A. Kadlec and A.G. van der Valk. 2000a. Introduction to the Marsh Ecology Research Program. In Prairie Wetland Ecology: The Contribution of the Marsh Ecology Research Program. (Eds) H.R. Murkin, A.G. van der Valk and W.R. Clark. pp. 3-15. Ames: Iowa State University Press. Resulting Publications on MERP climatic factors data: Kadlec, J.A. 1983. Water budgets for small diked marshes. Water Resources Bulletin 19: 223-229. Kadlec, J.A. 1993. Effects of depth of flooding on summer water budgets for small diked marshes. Wetlands 13: 1-9.