نتایج جستجو برای: vegetation density

تعداد نتایج: 453936  

ژورنال: مرتع 2021

Drought as a complex ecosystem crisis can affect vegetation density and health. Iran with an arid and semi-arid climate is exposed to this phenomenon. Therefore, it is necessary to evaluate the effect of drought on vegetation. The purpose of this study is to evaluate the effect of meteorological drought on vegetation dynamics in Iran. In this regard, using MATLAB software, SPEI index with time ...

2005
O. Durán V. Schatz H. J. Herrmann

Barchan dunes were found to transform into parabolic dunes and vice versa when the amount of vegetation on and around them changes. This work presents the first numerical simulation of this effect. We propose a continuum model for the density of vegetation. An established sand transport model is used for simulating the evolution of the dunes.

More than one-third of the earth is characterized by arid and semi-arid climate and desertification phenomenon in these areas has been intensified in recent decades. This study aims to investigate the trend of desertification using vegetation indices and Iranian Model of Desertification Potential Assessment (IMDPA) in Abarkooh Plain, Yazd province, Iran. The satellite images (Landsat images in ...

2014
Suyun Shang Scott X. Chang Zhaoliang Song Juan Liu Lei Sun

Data on the effect of vegetation and land use type on soil organic carbon (SOC) distribution in particle-size and density fractions in the subtropical forest region in China will improve our understanding of the C sequestration potential of those different vegetation-land use types. We quantified SOC in particle size (coarse, medium and fine) and density fractions (light and heavy) under four t...

2009
M.Z.A. Rahman

High density airborne LiDAR, for example FLI-MAP 400 data, has opened an opportunity for individual tree measurement. This paper presents a method for individual tree delineation and undergrowth vegetation removal in forest area. The delineation of individual trees involves two steps namely 1) tree crown delineation based on density of high points (DHP) and 2) separation of dominant trees and u...

2011
Bradley Evans Tom J. Lyons Paul A. Barber Christine Stone Giles Hardy

Remote sensing of vegetation condition using high resolution digital multispectral imagery (DMSI) is an option for land managers interested in quantifying the distribution and extent of dieback in native forest. Crown condition is assessed as reference to the physical structure and foliage (i.e. density, transparency, extent and in-crown distribution) of a tree crown. At 20 sites in the Yalgoru...

In dry lands, semi-circular bund has been considered as a management practice used to restore the ecological revival in terms of vegetation enrichment and soil amelioration. This study was conducted to investigate the effects of semi-circular bunds on vegetation cover and some soil properties in Koteh rangeland, Sistan and Baloochestan province, Iran (2014). Adjacent to the semi-circular bund a...

Journal: :Journal of plant physiology 2004
Anatoly A Gitelson

The Normalized Difference Vegetation Index (NDVI) is widely used for monitoring, analyzing, and mapping temporal and spatial distributions of physiological and biophysical characteristics of vegetation. It is well documented that the NDVI approaches saturation asymptotically under conditions of moderate-to-high aboveground biomass. While reflectance in the red region (rho(red)) exhibits a nearl...

Journal: :Journal of the American Mosquito Control Association 1990
W E Walton E T Schreiber M S Mulla

The distribution and abundance of mosquito larvae in a freshwater marsh were determined during a low water period in the late summer. Culex tarsalis larval abundance was significantly associated with the percent cover by Typha spp. root masses and Typha spp. stem density in 1-m2 quadrants. Larval mosquito abundance was not significantly related to bulrush (Scirpus californicus) stem density, po...

Drought and grazing rangelands play an important role in changing the structure of vegetation and losing the biodiversity of natural ecosystems. In this research, in order to determine the effects of drought and livestock grazing on the vegetation structure of rangelands located in the Nakhab Forest of South Khorasan Province, species abundance, biodiversity, and range condition and trend were ...

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