Table 2.
Mean (SE), range, and absolute values of D2 (k = 10) eigenvectors for environmental variables measured at 3184 sage-grouse leks, 99 historic but currently extant locations, and for the study area
| Active leks | Historic | Study area | |||||
|---|---|---|---|---|---|---|---|
| Environmental variables | Mean (SE) | Range | Mean (SE) | Range | Mean (SE) | Range | Eigenvector D2 (k = 10) |
| Land cover (%) | |||||||
| Big sagebrush shrubland | 29.8 (0.4) | 0–97.6 | 11.8 (1.3) | 0–66.1 | 15.3 (0.02) | 0–99.5 | 0.09 |
| Big sagebrush shrub steppe | 19.5 (0.4) | 0–94.5 | 8.0 (1.1) | 0–51.3 | 6.9 (0.01) | 0–100 | 0.33 |
| Low sagebrush | 20.1 (0.4) | 0–95.4 | 4.1 (0.9) | 0–59.1 | 8.0 (0.01) | 0–97.1 | 0.12 |
| Mountain sagebrush | 9.4 (0.3) | 0–89.1 | 3.7 (1.1) | 0–77.8 | 4.7 (0.01) | 0–98.8 | 0.10 |
| All sagebrush | 78.84 (0.33) | 1.93–99.98 | 34.87 (0.03) | 0–100 | 27.7 (2.01) | 0.43–80.22 | |
| Agriculture | 2.1 (0.1) | 0–83.1 | 26.6 (2.4) | 0–93.5 | 8.1 (0.02) | 0–97.8 | 0.36 |
| Conifer forest | 0.8 (0.1) | 0–44.4 | 3.4 (0.7) | 0–40.6 | 12.5 (0.03) | 0–99.1 | 0.21 |
| Developed land | 0.3 (0.01) | 0–14.1 | 8.7 (1.5) | 0–83.9 | 1.4 (0.004) | 0–99.5 | 0.04 |
| Grassland | 2.2 (0.1) | 0–71.0 | 9.8 (1.3) | 0–61.2 | 3.8 (0.01) | 0–84.1 | 0.09 |
| Riparian | 1.9 (0.1) | 0–33.5 | 2.2 (0.5) | 0–50.7 | 2.1 (0.003) | 0–87.1 | 0.10 |
| Burn | |||||||
| Burned area 1980–2007 (ha) | 1421 (40) | 0–7974 | 587 (121) | 0–6145 | 770 (2) | 0–7974 | 0.18 |
| Anthropogenic | |||||||
| Secondary roads (km/km2)1 | 66.6 (0.6) | 0–288.8 | 164.7 (16.5) | 26.3–1242.6 | 75.7 (0.1) | 0–1332.4 | 0.11 |
| Highways (km/km2)1 | 2.0 (0.1) | 0–32.3 | 11.0 (1.3) | 0–58.7 | 3.4 (0.01) | 0–77.1 | 0.12 |
| Interstate highways (km/km2)1 | 0.1 (0.02) | 0–19.8 | 3.8 (0.8) | 0–46.6 | 0.6 (0.003) | 0–52.0 | 0.33 |
| Power lines (km/km2)1 | 2.5 (0.1) | 0–34.6 | 14.4 (1.4) | 0–52.1 | 4.3 (0.01) | 0–79.5 | 0.11 |
| Pipelines (km/km2)1 | 1.4 (0.1) | 0–78.1 | 8.6 (1.5) | 0–64.3 | 2.7 (0.01) | 0–208.2 | 0.08 |
| Communication towers (towers/km2)1 | 0.1 (0.01) | 0–8.9 | 18.3 (5.5) | 0–286.5 | 0.6 (0.01) | 0–2005.3 | 0.22 |
| Soil | |||||||
| Soil depth (cm) | 102.6 (0.7) | 0–152.0 | 110.4 (4.1) | 0–152.0 | 104.0 (0.1) | 0–152.0 | 0.06 |
| Sand (% soil volume) | 28.8 (0.2) | 0–85.5 | 32.0 (1.7) | 0–90.2 | 30.5 (0.02) | 0–92.0 | 0.14 |
| Silt (% soil volume) | 28.3 (0.2) | 0–70.0 | 37.9 (1.7) | 0–70.0 | 30.0 (0.02) | 0–81.5 | 0.08 |
| Clay (% soil volume) | 21.5 (0.2) | 0–50.1 | 14.8 (0.7) | 0–34.5 | 15.8 (0.01) | 0–57.4 | 0.34 |
| Salinity (mmhos/cm) | 1.1 (0.02) | 0–10.7 | 0.9 (0.1) | 0–11.0 | 1.6 (0.003) | 0–21.1 | 0.16 |
| Available water capacity (cm/cm) | 4.2 (0.03) | 0–12.3 | 5.6 (0.3) | 0–12.3 | 4.7 (0.003) | 0–25.0 | 0.04 |
| Topography | |||||||
| Slope (degrees) | 3.1 (0.1) | 0–26.0 | 5.7 (0.7) | 0–36.0 | 7.3 (0.01) | 0–69.3 | 0.15 |
| Terrain ruggedness index | 1.0 (0.1) | 0–46.4 | 2.6 (0.7) | 0–55.1 | 4.1 (0.01) | 0–354.6 | 0.13 |
| Climate | |||||||
| Precipitation (mm) | 333.3 (1.6) | 169.0–835.8 | 329.3 (11.7) | 140.4–782.0 | 376.3 (0.2) | 76.4–3810.4 | 0.06 |
| Minimum temperature (°C) | −9.5 (0.04) | −17.0 to −3.9 | −6.6 (0.3) | −15.3 to −1.3 | −8.3 (0.003) | −19.6 to 3.9 | 0.09 |
| Maximum temperature (°C) | 30.5 (0.03) | 23.5–35.7 | 31.8 (0.2) | 21.7–37.6 | 30.9 (0.004) | 11.0–46.1 | 0.07 |
Land cover, burn area, and anthropogenic variables were measured within a 5-km radius of the lek. Soil, topography, and climate were measured at the lek location. Source data are available at http://sagemap.wr.usgs.gov.
1
Multiplied by 102.