Abstract
Abstract. Plant cover was visually estimated by five observers, independent of each other, in a species‐rich grassland in the Bílé Karpaty Mts., southeastern Czech Republic, in seven plots ranging from 0.001 to 4 m 2 . Variation of total plant cover among the observers was high at small scales: 0.001–0.016 m 2 ; coefficient of variation, CV = 35 to 45%, but much lower at larger scales: 0.06–4 m 2 ; CV = 7 to 15%. Differences between visual estimates of plant cover of individual species made by different observers were affected by plot size, total cover and morphology of particular plants. CV of the cover of individual species ranged from 0 to 225% and decreased with increasing plot size. For abundant plants the CV attained ca. 50%, independent of plot size. In spite of a very high number of sterile plants with similar leaf morphology and colour, the observed variation in cover estimates in the studied grassland was comparable with results reported from other vegetation types. Differences between estimates by individual observers were often larger than usual year to year changes in undisturbed grasslands. Therefore, I suggest that to avoid difficulties in the interpretation of results based on plant cover data obtained from visual estimates, several observers should always work together, adjusting their extreme estimates.
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Claims 8
Claim · model-written summary
Variation of total plant cover estimates among observers was high at small scales (0.001–0.016 m2), with CV of 35 to 45%.
Verbatim
e1“Variation of total plant cover among the observers was high at small scales: 0.001–0.016 m 2 ; coefficient of variation, CV = 35 to 45%”
e2“Bílé Karpaty Mts., southeastern Czech Republic”
t0“grassland plant cover”
Claim · model-written summary
Variation of total plant cover estimates among observers was much lower at larger scales (0.06–4 m2), with CV of 7 to 15%.
Verbatim
e1“Variation of total plant cover among the observers”
e2“much lower at larger scales: 0.06–4 m 2 ; CV = 7 to 15%”
t0“grassland plant cover”
Claim · model-written summary
CV of the cover of individual species ranged from 0 to 225% and decreased with increasing plot size.
Verbatim
e1“CV of the cover of individual species ranged from 0 to 225% and decreased with increasing plot size”
t0“grassland plant cover”
Claim · model-written summary
For abundant plants the CV of cover estimates attained about 50%, independent of plot size.
Verbatim
e1“For abundant plants the CV attained ca. 50%, independent of plot size”
t0“grassland plant cover”
Claim · model-written summary
Differences between observers in visual cover estimates of individual species were affected by plot size, total cover and morphology of the plants.
- Taxon
- grassland plantt0
- Treatment
- plot size, total cover and morphology of particular plantse1
- Outcome
- Differences between visual estimates of plant cover of individual species made by different observerse1
Not reportedDirection
Verbatim
e1“Differences between visual estimates of plant cover of individual species made by different observers were affected by plot size, total cover and morphology of particular plants”
t0“grassland plant cover”
Claim · model-written summary
The observed variation in cover estimates in the studied grassland was comparable with results reported from other vegetation types.
Verbatim
e1“the observed variation in cover estimates in the studied grassland was comparable with results reported from other vegetation types”
t0“grassland plant cover”
Claim · model-written summary
Differences between estimates by individual observers were often larger than usual year to year changes in undisturbed grasslands.
Verbatim
e1“Differences between estimates by individual observers were often larger than usual year to year changes in undisturbed grasslands”
t0“grassland plant cover”
Claim · model-written summary
The author suggests that several observers should always work together, adjusting their extreme estimates.
Verbatim
e1“several observers should always work together, adjusting their extreme estimates”
t0“grassland plant cover”