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| 文件类型： | 文章 |
|---|---|
| 所有的著者/提供者： | Melinda G Knutson; William B Richardson; David M Reineke; Brian R Gray; Jeffrey R Parmelee; Shawn E Weick |
| ISSN: | 1051-0761 |
| OCLC号码： | 484936209 |
| 语言注释： | English |
| 注意： | Plate 1. Natural wetland in Winona County, Minnesota, USA, July 2001. USGS photo by Andy Kimball. Plate 1. Agricultural constructed pond in Winona County, Minnesota, USA, July 2001. USGS photo by Andy Kimball. Fig. 1. Map of agricultural pond study sites located in Houston and Winona Counties in southeastern Minnesota, USA. Table 1. Habitat predictor variables selected a priori, based on the literature, with associated response variables (species richness and reproductive success) for agricultural ponds in Houston and Winona counties, Minnesota, 2000-2001. Table 1. Habitat predictor variables selected a priori, based on the literature, with associated response variables (species richness and reproductive success) for agricultural ponds in Houston and Winona counties, Minnesota, 2000-2001. Table 2. Habitat predictors and odds ratios (model-averaged) for agricultural ponds in Houston and Winona counties, Minnesota, 2000-2001. Fig. 2. Effects of total nitrogen, adjusted for tiger salamander ("amtrin") abundance and fish presence ("fish"), on the probability of amphibian species richness of 3 or higher in agricultural ponds in Houston and Winona Counties, Minnesota, 2000. The probability of high species richness, based on the logistic regression model, was estimated by: <tex-math>$prob = 1/\{1 + exp(-a_i + 2.13 \times POND\_AREA + 2.55 \times FISH - 1.89 \times AMTRIN + 3.15 \times TOTNITR)\}$</tex-math>, where a<sub>i</sub> is 1.43, 4.14, and 12.93 for the probability of being in species richness category 6 or more, 3-4 or higher, and 2-3 or higher, respectively. Fig. 3. Effects of total nitrogen, adjusted for vegetation ("veg") and fish presence ("fish"), on the probability of high reproductive success for two or more amphibian species in agricultural ponds in Houston and Winona Counties, Minnesota, 2000. The probability of high reproductive success for all species combined, based on the logistic regression model, was estimated by: prob = 1/[1 + exp(-11.78 + 1.45 x VEG_SUM + 7.94 x FISH + 23.70 x TOTNITR)]. Table 3. Validation of the best habitat models for agricultural ponds in Houston and Winona counties, Minnesota, 2000-2001. |
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摘要：
In some agricultural regions, natural wetlands are scarce, and constructed agricultural ponds may represent important alternative breeding habitats for amphibians. Properly managed, these agricultural ponds may effectively increase the total amount of breeding habitat and help to sustain populations. We studied small, constructed agricultural ponds in southeastern Minnesota to assess their value as amphibian breeding sites. Our study examined habitat factors associated with amphibian reproduction at two spatial scales: the pond and the landscape surrounding the pond. We found that small agricultural ponds in southeastern Minnesota provided breeding habitat for at least 10 species of amphibians. Species richness and multispecies reproductive success were more closely associated with characteristics of the pond (water quality, vegetation, and predators) compared with characteristics of the surrounding landscape, but individual species were associated with both pond and landscape variables. Ponds surrounded by row crops had similar species richness and reproductive success compared with natural wetlands and ponds surrounded by non-grazed pasture. Ponds used for watering livestock had elevated concentrations of phosphorus, higher turbidity, and a trend toward reduced amphibian reproductive success. Species richness was highest in small ponds, ponds with lower total nitrogen concentrations, tiger salamanders (Ambystoma tigrinum) present, and lacking fish. Multispecies reproductive success was best in ponds with lower total nitrogen concentrations, less emergent vegetation, and lacking fish. Habitat factors associated with higher reproductive success varied among individual species. We conclude that small, constructed farm ponds, properly managed, may help sustain amphibian populations in landscapes where natural wetland habitat is rare. We recommend management actions such as limiting livestock access to the pond to improve water quality, reducing nitrogen input, and avoiding the introduction of fish.