نتایج جستجو برای: forest stands
تعداد نتایج: 123621 فیلتر نتایج به سال:
Forest stands are the basic units for forest inventory and mapping. Stands are defined as large forested areas (e.g., ≥ 2ha) of homogeneous tree species composition and age. Their accurate delineation is usually performed by human operators through visual analysis of very high resolution (VHR) infra-red images. This task is tedious, highly time consuming, and should be automated for scalability...
A coherent scattering model for tree canopies is employed in order to characterize the sensitivity of an interferometric SAR (INSAR) response to the physical parameters of forest stands. The concept of an equivalent scatterer for a collection of scatterers within a pixel, representing the vegetation particles of tree structures, is used for identifying the scattering phase center of the pixel w...
To determine if bats prefer certain ages of aspen mixedwood forest for roosting and foraging, and to predict the impacts of logging on bats, we compared the relative abundances and foraging activities of bats in young, mature, and old stands in and , using bat detectors. In , we also assessed post-logging bat abundances in two of the mature and two of the old stands. We tracked rad...
Approximately 50,000 ha of native wet Metrosideros forest on the island of Hawai'i experienced a drastic reduction (dieback) of the tree canopy between 1954 and 1977. Two general hypotheses have previously been suggested to explain this phenomenon: 1) Metrosideros dieback has resulted from recently introduced pathogens, and 2) the dieback has naturally occurred previously in Hawai'i, and is rel...
BACKGROUND Forest fuel treatments have been proposed as tools to stabilize carbon stocks in fire-prone forests in the Western U.S.A. Although fuel treatments such as thinning and burning are known to immediately reduce forest carbon stocks, there are suggestions that these losses may be paid back over the long-term if treatments sufficiently reduce future wildfire severity, or prevent deforesta...
Invasive species pose major threats to the integrity and functioning of ecosystems. When such species alter ecosystem processes, they have the potential to change the environmental context in which other species survive and reproduce and may also facilitate the invasion of additional species. We describe impacts of an invasive N2-fixing tree, Falcataria moluccana, on some of the last intact rem...
Seasonal change in leaf area index (LAI) is highly important in remote sensing of land surface phenology because LAI is a main driving factor of forest reflectance. We present a time series of in situ measurements of boreal forest LAI expanding throughout the growing period from budburst to senescence. We measured the LAI of 20 stands at approximately two-week intervals between mid-May and mid-...
HAMDAN O, KHALI AZIZ H & ABD RAHMAN K. 2011. Remotely sensed L-band SAR data for tropical forest biomass estimation. Several attempts have been made to obtain forest stand parameters such as stand volume, stand density, basal area, biomass and carbon (C) stocks from synthetic aperture radar (SAR) data. However the relationship between these parameters and radar backscatter has been a challengin...
Accurate estimates of forest site productivity are essential for environmental planning and forest management. In this study, we developed a new productivity index, hereafter termed basal area potential productivity index (BAPP), to estimate site productivity for irregular and complex forests characterized by multi-aged, multi-species, and multi-layer stands. We presented the biological relevan...
This study examined the impact of logs and stumps on the understory composition of 28-yearold aspen-dominated boreal forests. Suitable logs covered more than five times the area of stumps in both harvest and wildfire stands. Logs and stumps were colonized by a significantly different assemblage of vascular plants than the forest floor. Initial colonization patterns on dead wood in both wildfire...
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