| | Accession Number | 5004265 |
| | Title | Vegetation monitoring at Balcones Canyonlands National Wildlife Refuge |
| | Project Description | The objective of this project is to monitor 32 vegetation plots established at the Balcones |
| | Canyonlands National Wildlife Refuge (BCNWR) in 1998. The BCNWR, currently at about 6,500 |
| | ha in area out of a proposed 18,600 ha reserve, was established in 1992 by buying parcels of |
| | existing cattle ranches to provide habitat for the golden-cheeked warbler (GCW), black- capped |
| | vireo (BCV), and other species. The GCW breeds in late-successional oak-cedar woodlands while |
| | the BCV breeds in early-successional habitat, and the refuge recently began controlled burning as |
| | a habitat restoration technique for the BCV. During 16-18 September 1998, we set-up and |
| | quantified the vegetation on these 32 vegetation plots, before any burning of BCV habitat occurred, |
| | with this initial work funded by the U.S. Geological Survey. The methods are described below, |
| | and these plots were remeasured again using the same methods during 15-16 September 2000, |
| | funded by the U.S. Fish and Wildlife Service (USFWS). Plots 1-16 were placed in currently |
| | occupied BCV habitat (n=6 plots) or vireo management areas (n=10 plots) in which BCNWR plans |
| | to restore the habitat via periodic burning. Each of these circular plots is 0.01 hectares in area |
| | (radius=5.64 m). Plots 17-32 were placed in currently occupied GCW habitat (n=10 plots) or |
| | transitional areas (n=6 plots) in which BCNWR plans to allow the habitat to regenerate naturally. |
| | Each of these circular plots is 0.02 hectares in area (radius=7.98 m). The larger plot size was |
| | used for the GCW plots because the trees and shrubs on these plots tended to be larger in |
| | stature, warranting a larger plot size (D. Mueller-Dombois and H. Ellenberg, 1974, Aims and |
| | Methods of Vegetation Ecology, John Wiley & Sons, pg 48). Approximate plot locations were |
| | chosen with the assistance of the Refuge Biologist, Dr. Chuck Sexton, to sample a variety of |
| | refuge tracts of all 4 habitat types within BCNWR. A partial randomization was then performed by |
| | choosing a random number for the number of meters to place each plot perpendicular to each |
| | main access road. This was done for logistical considerations to save time. Because we are |
| | interested in testing for change over time between the BCW occupied and management areas, |
| | and between the GCW occupied and transitional areas, this partial randomization (vs. plot |
| | locations chosen entirely at random) is not expected to greatly affect conclusions. Once each plot |
| | location was chosen, we marked the center of each plot with a rebar stake (1.2 m height, 0.95 |
| | cm diameter), painted orange at the top. We collected geographic positioning system (GPS) |
| | measurements using a military-grade GPS unit, both at the nearest location on each access road, |
| | and at the center of each plot. We used a rope of the appropriate radius to mark 8-10 locations |
| | around the perimeter of each plot, using orange flagging tape. This flagging tape is not expected to |
| | remain permanent and each plot perimeter will have to be reflagged during each visit. After the |
| | perimeter was flagged, a species list was constructed for each plot, separate for herbaceous and |
| | woody plants. William Carr, a botanist with The Nature Conservancy of Texas, was contracted for |
| | this work. We also estimated percent cover for each species using the relevT method |
| | (Mueller-Dombois and Ellenberg, 1974, pages 45-66), separate for herbaceous and woody plants, |
| | and in separate categories 2 m and > 2 m in height. We used a modified Braun- Blanquet |
| | cover-abundance scale for each species in each category: 5 (>75% cover); 4 (50-75% cover); 3 |
| | (25-50% cover); 2 (5-25% cover); 1 (<5% cover); and t (trace; a few or solitary number of |
| | individuals with very small cover value). After the plot establishment and relevTs were finished, we |
| | tagged up to 10 trees, saplings, or seedlings per plot in or near 12 of the GCW plots (plots 19-30) |
| | during 20-22 September 1998, to compare growth rates between GCW transitional and occupied |
| | areas. These trees were remeasured during 17-18 September 2000. Diamet |
| | Keywords | ashe juniper, black-capped vireo, controlled burn, dendroica chrysoparia, golden-cheeked warbler, |
| | juniperus ashei, quercus, vegetation monitoring, vireo atricapillus, |
| | Principal | Jeff S Hatfield, USGS Patuxent Wildlife Research Center: jeff_hatfield@usgs.gov; David D |
| | Investigators | Diamond, volunteer: david_diamond@usgs.gov; William Carr, The Nature Conservancy of Texas: ; |
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