نتایج جستجو برای: reduction of forest canopy

تعداد نتایج: 21203187  

Journal: :Ecology 2008
Patrick A Jansen Peter J van der Meer Frans Bongers

Spatial contagiousness of canopy dynamics-the tendency of canopy disturbances to occur nearby existing canopy openings due to an elevated risk of tree fall around gaps-has been demonstrated in many temperate-zone forests, but only inferentially for tropical forests. Hypothesized mechanisms increasing the risk of tree fall around tropical forest gaps are (1) increased tree exposure to wind aroun...

2006
JESSE O. BASH DAVID R. MILLER

A relaxed eddy accumulation (REA) system was designed to continuously measure total gaseous mercury (TGM) fluxes over a forest canopy. TGM concentration measurements were measured at 5-min intervals with a Tekran model 2537A mercury analyzer located above the forest canopy on a walk-up meteorological tower. Ten-minute averages for upand downdraft mercury concentrations were used to calculate th...

2000
Kell B. Wilson Paul J. Hanson Dennis D. Baldocchi

The energy balance components were measured above the ground surface of a temperate deciduous forest over an annual cycle using the eddy covariance technique. Over a year, the net radiation at the forest floor was 21.5% of that above the canopy, but this proportion was not constant, primarily because of the distinct phenological stages separated by the emergence and senescence of leaves. The do...

2003
Rachel J. Standish

Tradescantia fluminensis, commonly referred to as ‘tradescantia’, is an invasive weed of canopydepleted forest remnants. Previous research suggests that a reduction of tradescantia biomass to ~80 gm-2 (~40% cover) is compatible with native forest regeneration. I assessed herbicide application, hand weeding and artificial shading as methods for the control of tradescantia in two lowland podocarp...

Journal: :caspian journal of environmental sciences 2013
i. bagheri r. naghdi* a. moradmand jalali

water erosion causes severe soil damage in northern forests of iran which is associated with different rut depths in skid trails. the aim of this study was to assess rutting and soil displacement on skid trails to mitigate water erosion. therefore the research was carried out in eight parcels of district no 3 of shafarood forest in the north of iran. in order to evaluate the amount of erosion i...

Journal: :PloS one 2016
Ondřej Košulič Radek Michalko Vladimír Hula

Traditional woodland management created a mosaic of differently aged patches providing favorable conditions for a variety of arthropods. After abandonment of historical ownership patterns and traditional management and the deliberate transformation to high forest after World War II, large forest areas became darker and more homogeneous. This had significant negative consequences for biodiversit...

2013
Kathleen R. Aikens Laura L. Timms Christopher M. Buddle

The forest canopy offers a vertical gradient across which variation in predation pressure implies variation in refuge quality for arthropods. Direct and indirect experimental approaches were combined to assess whether canopy strata differ in ability to offer refuge to various arthropod groups. Vertical heterogeneity in impact of avian predators was quantified using exclosure cages in the unders...

2010
Yuri Knyazikhin Mitchell A. Schull Liang Xu Ranga B. Myneni Arindam Samanta

The concept of canopy spectral invariants expresses the observation that simple algebraic combinations of leaf and canopy spectral reflectance become wavelength independent and determine two canopy structure specific variables – the recollision and escape probabilities. These variables specify an accurate relationship between the spectral response of a vegetation canopy to incident solar radiat...

Journal: :Int. J. Applied Earth Observation and Geoinformation 2016
Francesco Chianucci Leonardo Disperati Donatella Guzzi Daniele Bianchini Vanni Nardino Cinzia Lastri Andrea Rindinella Piermaria Corona

Accurate estimates of forest canopy are essential for the characterization of forest ecosystems. Remotelysensed techniques provide a unique way to obtain estimates over spatially extensive areas, but their application is limited by the spectral and temporal resolution available from these systems, which is often not suited to meet regional or local objectives. The use of unmanned aerial vehicle...

Journal: :Ecological Informatics 2010
Daniela Stojanova Pance Panov Valentin Gjorgjioski Andrej Kobler Saso Dzeroski

6 High quality information on forest resources is important to forest ecosystem management. Tra7 ditional ground measurements are labor and resource intensive and at the same time expensive 8 and time consuming. For most of the Slovenian forests, there is extensive ground-based infor9 mation on forest properties of selected sample locations. However there is no continuous infor10 mation of obje...

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