A comparison of cover pole with standard vegetation monitoring methods

Authors: Toledo, David; Herrick, Jeffrey - Jeff; ABBOTT, LAURIE - New Mexico State University

Submitted to: Journal of Wildlife Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2009
Publication Date: 6/1/2010
Citation: Toledo, D.N., Herrick, J.E., Abbott, L. 2010. A comparison of cover pole with standard vegetation monitoring methods. Journal of Wildlife Management. 74:600-604.

Interpretive Summary: This study reports on a comparison of two different approaches to characterize wildlife habitat structure: visual assessment of visual obstruction of a cover pole, and simple vegetation height measurements completed. The comparisons were completed in grassland, shrubland and savanna plant communities. The results indicate that the two approaches generate comparable results. Based on these results propose that a more versatile and interpretable description of wildlife habitat can be generated using a line-point intercept method together with measurements of vegetation height and the proportion of the soil surface covered by large intercanopy gaps. The advantage of this approach over the cover pole is that the data can be used for a wide variety of objectives, in addition to wildlife habitat, reducing total monitoring costs.

Technical Abstract: The ability of resource managers to make informed decisions regarding wildlife habitat could be improved with the use of existing datasets and the use of cost effective, standardized methods to simultaneously quantify vertical and horizontal cover. The objectives of this study were to (1) characterize vegetation structure of three semi-arid plant communities to compare a traditional wildlife method (cover pole) and standard measurements of vegetation cover, composition, height and the proportion of the soil surface covered by large intercanopy gaps that are nationally applied; (2) use this information to define the types and amounts of habitat structure information that can be derived from these standard measurements, and (3) determine the extent to which these data may substitute for cover pole data. Visual obstruction (VO), the spatial distribution of large intercanopy gaps, and vegetation cover, composition, and height were measured between June and November of 2003 on 188 transects distributed among three arid and semi-arid vegetation types in southern and central New Mexico: shrub-invaded grassland, shrubland, and savanna. Results showed that VO was strongly correlated with vegetation height for the three communities when analyzed together and for the shrubland and savanna sites when analyzed independently, but were weakly correlated at the shrub-invaded grassland site, which had a smaller range of variation. Gap intercept variables were not correlated with VO at the shrub-invaded grassland, shrubland, or savanna sites illustrating how the VO method poorly reflects the horizontal distribution of vegetation throughout the sites. We propose that a more versatile and interpretable description of wildlife habitat can be generated using a line-point intercept method together with measurements of vegetation height and the proportion of the soil surface covered by large intercanopy gaps.