Comparison of Vegetation Sampling Procedures in a Disturbed Mixed-Grass Prairie
نویسندگان
چکیده
Researchers currently use many different vegetation sampling methods in grassland systems (Shmida 1984, Stohlgren and Bull 1998, Barbour et al 1999). Each method examines the landscape at a slightly different grain (unit of observation) and extent (total area under study). Variation of study resolution (grain and extent together) and sampling frequency influences estimates of species richness and requires careful consideration to achieve an optimum sampling strategy (Turner 1989, Wiens 1989, Pickett and Cadenasso 1995, Whittaker et al 2001). The objective of sampling a plant community is generally to gain an accurate representation of the entire community; however, methods must balance increases in accuracy at a desired resolution with the available sampling resources to develop a feasible and efficient sampling strategy. At Fort Sill, Oklahoma, we tested the point-intercept, contiguous quadrat, and modified Whittaker sampling procedures to determine the optimum vegetation samA fundamental principle of landscape ecology is that overall resolution of a study can be changed by varying the grain and extent of sampling. However, sampling methods yielding a desirable resolution may not be the most efficient in terms of data gathered per unit of effort. We tested three methods simultaneously to select the optimum sampling method and resolution for a vegetation survey at Fort Sill, Oklahoma. The military’s standard sampling method, the Land Condition Trend Analysis Program, uses a modified pointintercept method to inventory vegetation. The point-intercept method may not adequately assess effects of disturbance on species richness in grasslands, so we tested it against contiguous quadrats and modified Whittaker plots. The point-intercept method, low resolution, was completed in the shortest time; however, it produced the least species richness. Contiguous quadrats, high resolution, required the greatest time investment, but had the highest species richness. Species richness in modified Whittaker plots (four levels of resolution) produced data quality similar to contiguous quadrats, but in less time. Modified Whittaker plots were most efficient because they detected the greatest number of species per unit of sampling effort and provided data at different spatial scales. © 2003 Oklahoma Academy of Science Comparison of Vegetation Sampling Procedures in a Disturbed Mixed-Grass Prairie
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