Comparison of Distance-Measurement Techniques for Sampling Tussock Grassland Species in New Zealand
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CitationLaycock, W. A., & Batcheler, C. L. (1975). Comparison of distance-measurement techniques for sampling tussock grassland species in New Zealand. Journal of Range Management, 28(3), 235-239.
PublisherSociety for Range Management
JournalJournal of Range Management
AbstractFour distance-measurement techniques were tested in 1969 near the Craigieburn Research Station of the Forest and Range Experiment Station, New Zealand Forest Service. Two methods (closest individual and point-centered-quarter) are known to result in biased estimates of density in nonrandom plant populations, and the other two methods (angle-order and corrected-point-distance) have been reported to permit unbiased estimates in nonrandom populations. Sampled were two tussock grassland species in areas where true densities were determined by total counts. The corrected-point-distance method resulted in estimates within 20% of actual density for all populations, and appeared to be the most promising measurement method tested. The closest individual and point-centered-quarter methods gave badly biased (low) estimates of aggregated populations. Reasonably good estimates for some populations were obtained by the angle-order method, but it is time consuming. All methods appear to need additional theoretical work.