Analysis of the Spatial Distribution of Foliage by Two‐dimensional Point Quadrats

Wilson, J. Warren

doi:10.1111/j.1469-8137.1959.tb05340.x

Cited by 162 publications

(52 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is defined as total leaf area per canopy volume (Welles and Cohen 1996). The foliage density, defined in Koike (1985) as the expected value of leaf number penetrated by a straight line within a unit distance, is identical with the relative frequency or percentage frequency in Wilson (1959Wilson ( , 1960Wilson ( , 1965 or the density of foliage in MacArthur and Horn (1969).…”

Section: Suitable Parameters and Their Definitionsmentioning

confidence: 99%

Review of ground-based methods to measure the distribution of biomass in forest canopies

Seidel

Fleck

Leuschner

et al. 2011

Annals of Forest Science

View full text Add to dashboard Cite

& Context Ecological research and an effective forest management need accurate information on the structure of the forest canopy to understand the biochemical, physiological and biogeochemical processes within a forest. & Research question This paper reviews the currently available instruments for measuring the distribution of biomass within forest canopies. We compare the most well-established approaches and present the different measurable parameters. A special focus lies on the resolution of the obtained data. & Results It was found that only 3D laser scanners offer data with the resolution required by ecologists, private landholders, the forest industry and the public to detect trends in tree growth patterns and canopy interactions in all three spatial dimensions. But data validation, data analysis and parameter extraction are still under development, and the price of the instrument is quite high. & Conclusion Research should focus on the parameter extraction from terrestrial laser scanner data as this could allow the calculation of functional attributes for different sections of a canopy on a high spatial resolution. It could also help ecologists characterize the structure of forest stands in a quick and precise way.

show abstract

Section: Suitable Parameters and Their Definitionsmentioning

confidence: 99%

Review of ground-based methods to measure the distribution of biomass in forest canopies

Seidel

Fleck

Leuschner

et al. 2011

Annals of Forest Science

View full text Add to dashboard Cite

show abstract

“…Additionally, we measured maximum height at all plots. We measured projected dwarf shrub leaf and wood area using a 1 m 2 point quadrat and recorded all contacts between a vertically inserted needle and the vegetation at 81 points (Wilson, 1959). The leaf area of other vascular plants on the dwarf shrub plots was negligible.…”

Section: Measurementsmentioning

confidence: 99%

Contrasting radiation and soil heat fluxes in Arctic shrub and wet sedge tundra

et al. 2016

View full text Add to dashboard Cite

Abstract. Vegetation changes, such as shrub encroachment and wetland expansion, have been observed in many Arctic tundra regions. These changes feed back to permafrost and climate. Permafrost can be protected by soil shading through vegetation as it reduces the amount of solar energy available for thawing. Regional climate can be affected by a reduction in surface albedo as more energy is available for atmospheric and soil heating. Here, we compared the shortwave radiation budget of two common Arctic tundra vegetation types dominated by dwarf shrubs (Betula nana) and wet sedges (Eriophorum angustifolium) in North-East Siberia. We measured time series of the shortwave and longwave radiation budget above the canopy and transmitted radiation below the canopy. Additionally, we quantified soil temperature and heat flux as well as active layer thickness. The mean growing season albedo of dwarf shrubs was 0.15 ± 0.01, for sedges it was higher (0.17±0.02). Dwarf shrub transmittance was 0.36 ± 0.07 on average, and sedge transmittance was 0.28 ± 0.08. The standing dead leaves contributed strongly to the soil shading of wet sedges. Despite a lower albedo and less soil shading, the soil below dwarf shrubs conducted less heat resulting in a 17 cm shallower active layer as compared to sedges. This result was supported by additional, spatially distributed measurements of both vegetation types. Clouds were a major influencing factor for albedo and transmittance, particularly in sedge vegetation. Cloud cover reduced the albedo by 0.01 in dwarf shrubs and by 0.03 in sedges, while transmittance was increased by 0.08 and 0.10 in dwarf shrubs and sedges, respectively. Our results suggest that the observed deeper active layer below wet sedges is not primarily a result of the summer canopy radiation budget. Soil properties, such as soil albedo, moisture, and thermal conductivity, may be more influential, at least in our comparison between dwarf shrub vegetation on relatively dry patches and sedge vegetation with higher soil moisture.

show abstract

“…The habitat boundaries established by Williams et al (2012) were used to assign each grid point to a specific habitat, irrespective of their mosaic pattern of occurrence. Surface features (plant species, bare soil and boulder/rock) were recorded at each grid intersection using a point quadrat method (Wilson, 1959(Wilson, , 1960 but based on a flexible rope/string net (1.8 m × 1.8 m, with a 20 cm square mesh). The net was placed as close as possible to the ground surface, orientated north, by reference to a handheld magnetic compass, with the grid peg at its northwest corner.…”

Section: Surface Covermentioning

confidence: 99%

Trends, over 14 years, in the ground cover on an unimproved western hill grazed by sheep, and associated trends in animal performance

Walsh¹,

Hanrahan²,

O’Malley³

et al. 2016

Irish Journal of Agricultural and Food Research

View full text Add to dashboard Cite

The frequency of individual plant species at ground level and the species composition of the unimproved vegetation on a western hill farm, stocked with Scottish Blackface sheep, were monitored from 1995 to 2008. Performance criteria of the flock that relied totally, or almost totally, on this vegetation for sustenance from 1994 to 2011 were evaluated. The frequency of vegetation increased over time (from 65% to 82% of the surface area; P < 0.05), with a corresponding decline in the frequency of bare soil, thus reducing vulnerability to soil erosion. This increased incidence of vegetation cover reflected increases in ‘other forbs’(P < 0.01), heather(P < 0.05)and grass (P < 0.08).A significant change (P < 0.05) also occurred in the species composition of the vegetation, reflecting an increase in the proportions of ‘other forbs’ (P < 0.05) and heather (P = 0.14), and a decline in the proportion of sedges (P = 0.14). A similar pattern occurred in the two main habitats: blanket bog and wet heath. Annual stocking rate (ewes per hectare, based on actual ewe grazing days) on the unimproved hill grazing averaged 0.9 (0.13 livestock units) per hectare prior to 1999 and 0.78 (0.11 livestock units) per hectare subsequently. There was no trend in weight gain of replacement females while confined to the unimproved hill area between weaning (14 weeks old) and first joining at 18 months of age. A negative trend (P < 0.01) occurred in the pre-weaning growth rate of lambs on the hill. The average number of lambs reared per ewe joined (reflecting fertility, litter size and ewe/lamb mortality) was 1.0, and this showed no evidence of change over time. The study flock performed 10% to > 60% better, depending on the variable, than similar flocks in the National Farm Survey at comparable stocking rates. A well-defined rational management system can sustain a productive sheep enterprise on unimproved hill land without negative consequences for the frequency or composition of the vegetation.

show abstract

Analysis of the Spatial Distribution of Foliage by Two‐dimensional Point Quadrats

Cited by 162 publications

References 1 publication

Review of ground-based methods to measure the distribution of biomass in forest canopies

Review of ground-based methods to measure the distribution of biomass in forest canopies

Contrasting radiation and soil heat fluxes in Arctic shrub and wet sedge tundra

Trends, over 14 years, in the ground cover on an unimproved western hill grazed by sheep, and associated trends in animal performance

Contact Info

Product

Resources

About