نتایج جستجو برای: canopy cover perimeter

تعداد نتایج: 127446  

Journal: :Journal of human evolution 2015
Julien Louys Carlo Meloro Sarah Elton Peter Ditchfield Laura C Bishop

We test the performance of two models that use mammalian communities to reconstruct multivariate palaeoenvironments. While both models exploit the correlation between mammal communities (defined in terms of functional groups) and arboreal heterogeneity, the first uses a multiple multivariate regression of community structure and arboreal heterogeneity, while the second uses a linear regression ...

Journal: :Remote Sensing 2012
Steen Magnussen Michael A. Wulder

Canopy height data collected with an airborne laser scanner (ALS) flown across unmanaged parts of Canada’s boreal forest in the summer of 2010 were used—as stand-alone data—to derive a least-squares polynomial (LSPOL) between presumed post-fire recovered canopy heights and duration (in years) since fire (YSF). Flight lines of the >25,000-km ALS survey intersected 163 historic fires with a known...

2016
Robert Koprowski Paweł Kasprowski Marek Rzendkowski

BACKGROUND Currently available perimeters have limited capabilities of performing measurements of the visual field in children. In addition, they do not allow for fully automatic measurement even in adults. The patient in each case (in any type of perimeter) has at his disposal a button which he uses to indicate that he has seen a light stimulus. Such restrictions have been offset in the presen...

2005
JONATHAN K. WEBB RICHARD SHINE ROBERT M. PRINGLE

In the last two centuries, European fire suppression practices have produced increases in vegetation density and canopy cover in many landscapes. Potentially, increases in canopy cover could negatively affect small populations of nocturnal reptiles that use sun-exposed shelters for diurnal thermoregulation. We hypothesized that vegetation encroachment over rock outcrops might partly explain the...

Journal: :Remote Sensing 2017
Jucai Li Wenjie Fan Yuan Liu Gaolong Zhu Jingjing Peng Xiru Xu

In contrast to herbaceous canopies and forests, savannas are grassland ecosystems with sparsely distributed individual trees, so the canopy is spatially heterogeneous and open, whereas the woody cover in savannas, e.g., tree cover, adversely affects ecosystem structures and functions. Studies have shown that the dynamics of canopy structure are related to available water, climate, and human act...

2002
Joseph E. Crouse

Overstory vegetation maps of species and canopy cover were developed from Landsat 7 Thematic Enhanced Thematic Mapper satellite imagery. Ecosystem Monitoring plot data, collected during the 1997-2001 field seasons, were used as training sites for the image classification. Sixty-two species classes and four canopy cover classes were mapped. The maps will be used to support a Joint Fire Science P...

2000
William P. Kustas John H. Prueger Jerry L. Hatfield Kalia Ramalingam Lawrence E. Hipps

For many natural and agricultural landscapes, vegetation partially covers the ground surface, resulting in significant variations in soil heat flux between interspace areas and underneath vegetation. This is particularly apparent in arid and semiarid regions where vegetation cover is low and clustered or ‘clumped’ with large areas of exposed soil. Surface heterogeneity presents significant chal...

Forest fragmentation results in a loss of forest interior and an increase in edge habitat. We studied how understorey bird community composition and habitat variables changed along an edge-to-interior gradient in a 1248-ha lowland rainforest patch in peninsular Malaysia. Birds and environmental variables such as vegetation structure and litter depth were detected within a 25-m radius of each of...

2015
Elizabeth A. Roznik Sarah J. Sapsford David A. Pike Lin Schwarzkopf Ross A. Alford

Natural disturbances can drive disease dynamics in animal populations by altering the microclimates experienced by hosts and their pathogens. Many pathogens are highly sensitive to temperature and moisture, and therefore small changes in habitat structure can alter the microclimate in ways that increase or decrease infection prevalence and intensity in host populations. Here we show that a redu...

2000
N. A. Jackson

Rainfall interception losses from an agroforestry system in semi-arid Kenya comprising Grevillea robusta and maize were measured over a period of 33 months. These measurements showed that interception was slightly higher (10.2%) under trees with no maize understorey, than in the intercropped treatment (9.8%), and was directly related to the degree of tree canopy cover. Interception estimates us...

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