Agricultural ponds support amphibian populations
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Authors: M. G. Knutson, W. B. Richardson, D. M. Reineke, B. R. Gray, J. R. Parmelee, and S. E. Weick
Date: 2004
Journal: Ecological Applications
Volume: 14
Number: 3
Pages: 669-684
Summary of Methods: Reduction of amphibian populations was investigated by looking at 40 ponds in the agricultural region of southeastern Minnesota, northeastern Iowa, and southwestern Wisconsin to determine what characteristics of man-made ponds versus naturally occurring ponds created better habitat for amphibians. Thirty of the ponds were constructed, while ten were naturally occurring. Both types had row crops, grazing pastures, or non-grazing pastures within 30 meters. Amphibian larvae and metamorphs were surveyed in the ponds from April until August in 2000 and 2001. Habitat characteristics including water quality, pond depth and size, aquatic vegetation, and aquatic predators were also measured. These measurements were modeled to determine the set of variables that best predicted the positive and negative effects on amphibian reproduction.
Article Summary / Main Points: Natural ponds had more aquatic vegetation, lower turbidity, and lower nutrient concentrations. These three characteristics along with predators were the most important when predicting overall amphibian reproductive success and species richness. Due to the disturbances caused by grazing, which increase nitrogen and turbidity and lower vegetation cover, livestock may negatively affect amphibian reproduction. Constructed ponds that are livestock free would have greater benefit to amphibian populations than constructed ponds that are impacted by agricultural practices.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: 105 Northern Mississippi Valley Loess Hills
Agrovoc Control Words: Riparian zones Rangelands Amphibians
Article Review Type: Refereed
Article Type: Documented Case History
Keywords: agricultural pond, agriculture, amphibian, driftless area ecoregion, farm pond, fish, habitat management, landscape, livestock grazing, nitrogen, stock pond, water quality
Annotation: This study was one of the first to look at the effects of agriculture on amphibian reproduction and provides useful information on what aspects of grazing most affect amphibians. It does not attempt to predict the baseline population of amphibians if only natural ponds occurred, but rather is just a comparison between constructed and natural ponds. The ages of the ponds were not established and could be important in amphibian response to agriculture. The factors included above and in the abstract are typically mitigated by proper grazing management and runoff control. Properly managed constructed ponds could be critical in regions with few natural ponds.
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