Scale-dependent biases in species counts in a grassland
Article first published online: 24 FEB 2009
2001 IAVS - the International Association of Vegetation Science
Journal of Vegetation Science
Volume 12, Issue 5, pages 699–704, October 2001
How to Cite
Klimeš, L., Dančak, M., Hájek, M., Jongepierová, I. and Kučera, T. (2001), Scale-dependent biases in species counts in a grassland. Journal of Vegetation Science, 12: 699–704. doi: 10.2307/3236910
- Issue published online: 24 FEB 2009
- Article first published online: 24 FEB 2009
- Received 10 January 2000; Revision received 18 June 2001; Accepted 27 June 2001. Coordinating Editor: J. Oksanen.
- Sampling error;
- Species richness estimate;
- Species-rich meadow
Abstract. Numbers of plant species were recorded in species-rich meadows in the Bílé Karpaty Mts., SE Czech Republic, with the aim to evaluate the sampling error made by well-trained observers. Five observers recorded vascular plants in seven plots ranging from 9.8 cm2 to 4 m2 independently and were not time-limited. In larger plots a discrepancy of 10–20% was found between individual estimates, in smaller plots discrepancy increased to 33%, on average. The gain in observed species richness by combining records of individual observers (in comparison with the mean numbers estimated by single observers) decreased from the smallest plot (27–82% for two to five observers) to the largest one (13–25%). However, after misidentified and suspicious records were eliminated, the gain was much lower and became scale-independent; two observers added 12% species, on average, and the increase by combining species lists made by three or more observers was negligible (3% more on average). It is concluded that most discrepancies between individual observers were caused by misidentification of rare seedlings and young plants. We suggest that in species-rich meadows plants should be recorded by at least three observers together and that they should consult all problematic plant specimens together in the field, to minimize errors.