Measuring and Monitoring Plant Populations

Carpenter, Alan T.; Elzinga, C. L.; Salzer, D. W.; Willoughby, John W.

doi:10.2307/4003786

Cited by 30 publications

(44 citation statements)

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“…In each subplot, we assessed herbaceous vascular plants by selecting only plants that did not possess a woody stem above ground at maturity and counted their abundance (individual plant number). When a species was very dominant in one subplot, we estimated their abundance by extrapolating the number of individual plant from a small area (10 cm x 10 cm) in which we could count the individual plant (Carpenter et al, 1999). We also attributed each species to one of the following categories based on its growth form: fern, vine (climbing plants excluding fern), graminoids (Poaceae and Cyperaceae) and other herb (non-climbing flowering herbs).…”

Section: Herbaceous Plants Assessment and Species Origin Categorisamentioning

confidence: 99%

Land‐use intensification increases richness of native and exotic herbaceous plants, but not endemics, in Malagasy vanilla landscapes

Raveloaritiana

Wurz

Graß

et al. 2021

Diversity and Distributions

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Section: Herbaceous Plants Assessment and Species Origin Categorisamentioning

confidence: 99%

Land‐use intensification increases richness of native and exotic herbaceous plants, but not endemics, in Malagasy vanilla landscapes

Raveloaritiana

Wurz

Graß

et al. 2021

Diversity and Distributions

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show abstract

“…Second, were employed the point-intercept method Elzinga et al [53], based on four transects of 20 m located 20 m apart from each other, each containing 41 sampling points 30 cm from each other. Lichen species were registered at each sampling quadrat and point along transects (Fig.…”

Section: Sampling Designmentioning

confidence: 99%

Diversity of Saxicolous Lichens along an Aridity Gradient in Central M閤ico

Soto-Correa¹,

Salda馻-Vega²,

Cambr髇-Sandoval³

et al. 2022

Phyton

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Lichens are symbiotic organisms that comprise a fungus and a photosynthetic partner wich are recognized as a good indicator of climate change. However, our understanding of how aridity affects the diversity of saxicolous lichens in drylands is still limited. To evaluate the relationship between saxicolous lichen diversity and aridity in a central México dryland, a geographical transect was established of 100 km to build an aridity gradient in the semiarid zone of the State of Querétaro, Mexico, comprising ten sampling sites with a 10 km separation. Species richness, abundance and diversity of soil lichen species were recorded using two sampling methods: the quadrat-intercept and the line-intercept method, to compare their performance in assessing soil lichen diversity in drylands. The number of species and Shannon diversity of saxicolous lichens were higher at intermediate values of the aridity index (AI = 0.10-0.34). Quadrat intercept and point intercept methods gave quite similar results, which means that the selected method does not influence the results in a significant way. This study confirms the role of saxicolous lichens as climate change indicators and reveals the importance of the sampling method selection in the evaluation of different parameters of soil lichen diversity in drylands.

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“…However, the method tends not to be used for taxa that occur at high densities, such as many plants. Instead, direct count methods—generally based on a strip, plot or plotless design that assumes perfect detection—are preferred (Bonar et al., 2010; Carpenter et al., 1999; Hill, 2005; Shiver & Borders, 1996). In the authors' experience, reluctance to use distance methods is influenced by the perception that the method is impractical: the standard implementation requires measuring distance to all observed targets, which means very frequent measuring when detections are common.…”

Section: Introductionmentioning

confidence: 99%

Efficient effort allocation in line‐transect distance sampling of high‐density species: When to walk further, measure less‐often and gain precision

et al. 2021

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Line‐transect distance sampling is widely used to estimate population densities using distances of observed targets from transect lines to model detectability. When the target taxa are high density, the frequent measuring of distances may make the method seem impractical. We present a method that improves the efficiency of distance sampling when the target species occurs at high density. Only a proportion of targets are measured to model the detection function, and the time saved on the survey is then used to cover a longer total length of transect and accrue a larger ‘count only’ sample. This approach can improve the precision of the population density estimate when the cost of measuring the distance to a detected target is more than half the cost of walking to the next target. We find the optimal proportion of distances to measure that minimises the variance of the density estimate for a fixed survey budget. We quantify how much this optimised strategy increases the precision of the density estimate compared with conventional line‐transect distance sampling. We then use simulated distance sampling data to test our expressions, and illustrate circumstances under which the optimised approach would be beneficial using distance sampling data on high‐density plants. The simulations indicate that the optimised method delivers benefits in precision, but the magnitude of the benefit is lower than predicted from our expressions, which are based on an asymptotic approximation of the variance. We apply an adjustment to the predicted benefit equation to account for this difference, and show that, in all three plant case studies, the optimised approach could improve the precision gained from a distance sampling survey between 20% and 50%. This new approach could broaden the ecological contexts in which distance sampling is applied, to include estimation of densities of abundant taxa where plots are conventionally used. The method may have interesting applications for other survey types, including multispecies surveys or those using cues or signs that occur at high density.

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Measuring and Monitoring Plant Populations

Cited by 30 publications

References 0 publications

Land‐use intensification increases richness of native and exotic herbaceous plants, but not endemics, in Malagasy vanilla landscapes

Land‐use intensification increases richness of native and exotic herbaceous plants, but not endemics, in Malagasy vanilla landscapes

Diversity of Saxicolous Lichens along an Aridity Gradient in Central M閤ico

Efficient effort allocation in line‐transect distance sampling of high‐density species: When to walk further, measure less‐often and gain precision

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