Appendix C (TABLE C1). Descriptive statistics for the explanatory variables for the 18 surveyed wetlands included in the analyses.
| Variable name | Definition | Mean | S.D. | Range |
| Wetland variables | ||||
| FROGS | No. of frog and toad species | 4.4 | 1.69 | 1–7 |
| FWGS | No. of freshwater gastropod species | 3.3 | 1.53 | 2–7 |
| NPLAN | Abundance of Planorbella snails (per person search hour) | 17.1 | 33.74 | 0–140 |
| VEGS | No. of plant species | 13.9 | 6.54 | 5–27 |
| %TYPH | Line transects composed of Typha spp. (%) | 23.2 | 32.72 | 0–98.0 |
| %PHAL | Line transects composed of Phalaris spp. (%) | 16.7 | 25.53 | 0–80.5 |
| SOILOM | Organic matter of soil samples (%) | 10.7 | 7.13 | 3–33.1 |
| SUMATRAZ | Sum of atrazine and desethylatrazine (ppb) detected in water | 0.18 | 0.15 | 0–0.59 |
| SUMPAH | Sum of naphthalene and phenanthrene (ppb) detected in water | 0.48 | 0.54 | 0.08–1.8 |
| MAXN | Maximum nitrate detected in water (ppm) | 3.1 | 5.56 | 0.05–23.8 |
| MAXP | Maximum phosphate detected in water (ppm) | 0.61 | 0.85 | 0.05–3.5 |
| Local variables | ||||
| DISTAG | Distance to nearest agriculture patch (m) | 91.7 | 149.75 | 10–600 |
| DISTFOR | Distance to nearest forest patch (m) | 80.6 | 127.21 | 10–400 |
| DISTRLD | Distance to nearest low density residential area (m) | 288.9 | 462.08 | 10–2000 |
| DISTOW | Distance to open water patch (m) | 275.0 | 189.62 | 50–700 |
| DISTWW | Distance to woody wetland patch (m) | 482.8 | 483.14 | 10–2000 |
| FORLD-1k | Land composed of forest (%) | 14.6 | 7.12 | 3.4–28.1 |
| FORPD-1k | Patch density of forest (per km2) | 12.0 | 3.51 | 5.8–18.5 |
| WWLPI-1k | Land comprised of largest patch of woody wetland (%) | 1.6 | 1.66 | 0–6.5 |
| WWMNN-1k | Mean distances between patches of woody wetland (m) | 218.8 | 179.02 | 0–572.6 |
| OWMPS-1k | Mean patch size of open water (km2) | 3.4 | 7.27 | 0.14–32.1 |
| PWLD-1k | Land composed of palustrine-emergent wetland (%) | 11.3 | 7.59 | 2.2–33.3 |
| AGLD-1k | Land composed of agriculture (%) | 28.9 | 12.19 | 7.8–45.9 |
| Regional variables | ||||
| FORLD-10k | Land composed of forest (%) | 14.1 | 5.83 | 5.7–25.5 |
| WWPD-10k | Patch density of woody wetland (per km2) | 1.6 | 0.76 | 0.58–3.3 |
| WWLPI-10k | Land comprised of largest patch of woody wetland (%) | 0.33 | 0.35 | 0.10–1.3 |
| WWMNN-10k | Mean distances between patches of woody wetland (m) | 200.9 | 67.76 | 100.6–354.2 |
| OWMPS-10k | Mean patch size of open water (km2) | 4.9 | 3.43 | 1.6–12.4 |
| PWLD-10k | Land composed of palustrine-emergent wetland (%) | 10.9 | 1.17 | 9.3–13.7 |
| AGLD-10k | Land composed of agriculture (%) | 33.2 | 8.53 | 17.2–45.9 |
| AGPD-10k | Patch density of agriculture (per km2) | 7.6 | 3.92 | 4.6–21.1 |
| AGLPI-10k | Land comprised of largest patch of agriculture (%) | 14.4 | 11.54 | 0.62–24.1 |
LITERATURE CITED
Vogelmann, J. E., S. M. Howard, L. Yang, C. R. Larson, B. K. Wylie, and N. Van Driel. 2001. Completion of the 1990s National Land Cover dataset for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources. Photogrammetric Engineering and Remote Sensing 67:650–684.