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GIS & Data Integration
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Implementation of A Geographic Information System (GIS) to Determine Wildlife Habitat Quality Using Habitat Suitability Index
2.3 Automated HSI Model
The first step in developing the automated HSI model was to spatially join attribute data with stand and sample plot locations. Since stands were delineated mainly by their ecological land type and vegetation structure, it should be valid to treat stand as a homogeneous habitat area and to use stands as spatial boundary to expand point inventory data. Spatial Analyst was used to allocate the point sample plot attributes based on which stand polygons they fell in. Hence, an ecological site map was created to describe ecosystem information of each site. Stand polygons in Compartment One were then rasterized with cell size of 10 meter square. Habitat variables were extracted from the database according to requirements of each HSI models. Life requisite values of each species were then generated for each cell. A moving window the size of the home ranges of each species was applied to calculate the average value of each life requisites. Different target species had different window size according to their home range (Table 1). For each cell in the grid ecological site map, the neighborhood-analysis function computed an average value based on the value of the cells within the home range.
Finally, for each species of interest a habitat unit map was generated. The final index of each species equaled the minimum value of each life requisite, cell by cell.
3. Results
Four species was evaluated high in HSI values in Compartment One of Missouri Ozark Forest. Overall, gray squirrel had a relatively high HSI value in Compartment One (Figure 1). More than 80 percent of the area had HSI values higher than 0.5 (Table 2). The winter food life requisite had very high value in most of the cells. The cover requisite was lower mainly because the average dbh of overstory trees was too small. Eastern cottontail had very high HSI value for all of the cells (Figure 1). The successional stage of Compartment One was right where the optimum habitat the model described for eastern cottontail -- a forested landscape with middle shrub coverage and canopy coverage, and a relatively low nonwoody vegetation coverage. More than 85 percent of the cells had HSI values greater than 0.75 (Table 2). Bobcat also had high HSI value for all of the cells (Figure 1) mainly because the HSI model considered bobcat's prey, eastern cottontail and cotton rat, as the only life requisite, the result coincided with eastern cottontail. Most of the cells, more than 75 percent, in Compartment One had a HSI value higher than 0.5 (Table 2). Examination of the image (Figure 1) for bobcat showed that the higher value cells tend to form a continuous area. Compartment One was also evaluated high in all of the habitat variables of the downy woodpecker HSI model (Figure 1). Over 73 percent of the cells had HSI value larger than 0.5 with the high value distributed equally between range 0.5 - 0.75 and range 0.75 -1.00 (Table 2).
Figure 1. Habitat Suitability Index maps (1) barred owl (2) bobcat (3) brown thrasher (4) downy woodprcker (5) eastern cottontail (6) fox squirrel (7) gray squirrel (8) hairry woodpecker (9) northern bobwhite (10) pileated woodpecker (11) eastern wild turkey
Contrary to grat squirrel, fox squirrel was low in HSI. All of the cells had a HSI value for less than 0.5 (Figure 1). This was mainly due to the distance to available grain in this large forested area. Barred owl had low HSI value for most of the cells (Fig 1), more than 74 percent of the area. This result was a function of habitat variables which measured the number of big trees. Brown thrasher also had low HSI values (Fig 1). The high HSI value cells occurred where the canopy coverage was lower. Eastern wild turkey was low on HSI values (Figure 1). About 95 percent of the cells had HSI value lower than 0.5 (Table 2). This was mainly because of the optimum herbaceous coverage for eastern wild turkey was not provided by Compartment One. Northern bobwhite required low, dense woody vegetation and grassy areas. Therefore, the HSI value of northern bobwhite was low in Compartment One. Pileated woodpecker had the lowest HSI value among the 11 selected species. It required mature, dense forest with large snags, which was not available in Compartment One (Figure 1).
The HSI value for the hairy woodpecker ranged from 0 to 1 (Figure 1). However, there was a big gap between the low value and high value cells. This was because of the number of very large snags per hectare required in the HSI model, a stand with a few large snags could have very high SI value while a stand with no large snags had a SI value of 0.
For each species, the factor that dominates the final HSI value differs. However, the species that are low in HSI and high in HSI have some common characteristics. For species that prefer open forests such as fox squirrel and turkey, the HSI value is low because Compartment One is a dense forest. Early successional species such as northern bobwhite and brown thrasher that require low dense woody vegetation with a less dense overstory canopy have low HSI values. The optimum habitat of later successional species such as pileated woodpecker, barred owl, and turkey requires more large trees then is currently provided by Compartment One.
Species with high HSI values tend to prefer mid-successional habitat. The optimum habitat of species such as downy woodpecker, eastern cottontail and gray squirrel require dense forest with nearly closed canopies, abundant understory cover with moderate shrub and herbaceous coverage (20-50%), and existence of some small snags.
However, there are species with very specific needs. The hairy woodpecker, for example, prefers fairly large snags and large trees and its HSI values vary widely over Compartment One (Figure1).
Table 2. Area of habitat evaluation
| Species | Poor Habitat | Good Habitat
| | (Hectare)
| (%) | (Hectare) | (%)
| | Barred
owl | 25,807 | 74.22 | 8,962 | 25.78
| | Bobcat
| 8,604 | 24.75 | 26,165 | 75.25
| | Brown
thrasher | 34,573 | 99.44 | 196 | 0.56
| | Down
woodpecker | 9,311 | 26.78 | 25,458 | 73.22
| | Eastern
cottontail | 0 | 0 | 34,769 | 100
| | Fox
squirrel | 34,769 | 100
| 0 | 0
| | Gray
squirrel | 5,528 | 15.90 | 29,241 | 84.10
| | Hairy
woodpecker | 19,015 | 54.69 | 15,754
| 45.31
| | Northern
bobwhite | 34,769 | 100 | 0 | 0
| | Pileated
woodpecker | 34,769 | 100 | 0 | 0
| | Turkey
| 32,937 | 94.73 | 1,832 | 5.27
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5. Conclusions
A quantitative basis for management decisions may reduce the perception of subjective bias in decision making. This study provides a possible quantitative way to monitor management practices for ecosystem management by using HSI models. HSI models quantify habitat quality and permit consideration of wildlife along with other aspects of project planning, such as engineering and economics. They allow assessments of resultant changes in potential habitat quality and availability for selected wildlife species. This study's major contribution is the HIS incooperating spatial reseasoning and the redevelopment of spatially computed HSI. The use of a moving window that represents an animal's home range enabled the spatial evaluation of the habitat condition home range by home range. Thus, the HSI value of the each cell reflects the habitat condition of each species' home range, not the condition of one pixel. The moving window approach assessed the conditions of the home range at each point within each stand. Therefore, the automated HSI is not an assessment of the forest condition at each point but an assessment of habitat conditions of the home range (moving window). Futhermore, HSI habitat map shows the spatial distribution of poor habitat areas that need management attention and the good habitat areas that the manager may want to be careful about when harvesting or other activities are implemented.
6. Bibliography
- Allen, A.W. 1982. Habitat Suitability Index Models: Fox Squirrel. U.S. Dept. Int., Fish Wildl. Serv. FWS/OBS-82/10.18. 11pp.
- Allen, A.W. 1982. Habitat Suitability Index Models: Gray Squirrel. U.S. Dept. Int., Fish Wildl. Serv. FWS/OBS-82/10.19. 11pp.
- Allen, A.W. 1984. Habitat Suitability Index Models: Eastern Cottontail. U.S. Dept. Int., Fish Wildl. Serv. FWS/OBS-82/10.66. 23pp.
- Allen, A.W. 1987. Habitat Suitability Index Models: Barred Owl. U.S. Dept. Int., Fish Wildl. Serv. FWS/OBS-82/10.143. 17pp.
- Boyle, K.A., and T.T. Fendley. 1987. Habitat Suitability Index Models: Bobcat. U.S. Fist Wildl. Serv. Biol. Rep. 82(10.147). 16pp.
- Cade, B.S. 1986. Habitat Suitability Index Models: Brown Thrasher. U.S. Dept. Int., Fish Wildl. Serv. FWS/OBS-82/10.118. 14pp.
- Carroll, C. Ronald and Gary K. Meffe. 1994. Management to Meet Conservation Goals: Applications in Gary K. Meffe and C. Ronald Carroll, book, Principles of Conservation Biology.
- Eaton, Stephen W. 1992. Wild Turkey. The birds of North America, No. 22. 21pp.
- Grumbine, R. Edward. 1994. What is Ecosystem Management? Conservation Biology 8(1):27-38.
- Irland Lloyd C. 1994. Getting from Here to There: Implementing Ecosystem Management on the Ground. J. of Forestry 92(8):12-17.
- Noss, Reed F. and Allen Y. Cooperrider. 1994. Saving Nature's Legacy: Protecting and Restoring Biiodiversity. Island Press, Washington, D.C.
- Schroeder, R.L. 1982. Habitat Suitability Index Models: Downy Woodpecker. U.S. Dept. Int., Fish Wildl. Serv. FWS/OBS-82/10.38. 10pp.
- Schroeder, R.L. 1982. Habitat Suitability Index Models: Pileated Woodpecker. U.S. Dept. Int., Fish Wildl. Serv. FWS/OBS-82/10.39. 15pp.
- Schroeder, R.L. 1985. Habitat Suitability Index Models: Eastern Wild Turkey. U.S. Dept. Int., Fish Wildl. Serv. FWS/OBS-82/10.106. 33pp.
- Schroeder, R.L. 1985. Habitat Suitability Index Models: Northern Bobwhite. U.S. Dept. Int., Fish Wildl. Serv. FWS/OBS-82/10.104. 32pp.
- Schwartz, Charles W., and Elizabeth R. Schwartz, 1981. The Wild Mammals of Missouri. University of Missouri Press and Missouri Department of Conservation, 356pp.
- Sousa, Patrick J. 1987. Habitat Suitability Index Models: Hairy Woodpecker. U.S. Dept. Int., Fish Wildl. Serv. FWS/OBS-82/10.146. 19pp.
- USDA. 1994. An Ecological Basis for Ecosystem Management. USDA Forest Service, General Technical Report RM-246. Washington DC. 22pp.
- Whittaker, R. H. 1956. Vegetation of the Great Smoky Mountains. Ecol. Monogr. 26:1-80.
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