نتایج جستجو برای: vegetation cover

تعداد نتایج: 148562  

Journal: :journal of rangeland science 2010
a. mirjalili

in this investigation, the effects of enclosure, restal delayed grazing andcontinued grazing treatments on the production rate and vegetation cover were studied.study area was sadrabad pasture. after selecting three bands (1+1+1=3 hectare area) asthree treatments in the restricted and non restricted area, they were transected to threetransects. then plots (1×2m2 ) were selected to measure the p...

Journal: :ISPRS Int. J. Geo-Information 2012
Ronald C. Estoque Ria S. Estoque Yuji Murayama

Analysis of spatial and temporal changes of vegetation cover using remote sensing (RS) technology, in conjunction with Geographic Information Systems (GIS), is becoming increasingly important in environmental conservation. The objective of this study was to use RS data and GIS techniques to assess the vegetation cover in 1989 and 2009, in the barangays (smallest administrative units) of the cit...

ژورنال: علوم آب و خاک 2007
احمد جلالیان, , حسین خادمی, , مریم یوسفی فرد, ,

Improper use of natural resources, especially soil, causes its degradation and severe soil erosion. Water erosion is an important factor causing soil degradation. Land use change of pasture would result in severe soil erosion mainly due to the reduction of vegetation cover and also surface soil disturbance. The objectives of this study were to estimate the amount of sediment, runoff and nutrien...

Journal: :Remote Sensing 2014
Xiaohui Yang Xulin Guo

Spectral vegetation indices have been the primary resources for characterizing grassland vegetation based on remotely sensed data. However, the use of spectral indices for vegetation characterization in grasslands has been challenged by the confounding effects from external factors, such as soil properties, dead materials, and shadowing of vegetation canopies. Dead materials refer to the dead c...

2014
Y. Wang M. L. Roderick Y. Shen F. Sun

Terrestrial vegetation dynamics are closely influenced by both climate and by both climate and by land use and/or land cover change (LULCC) caused by human activities. Both can change over time in a monotonic way and it can be difficult to separate the effects of climate change from LULCC on vegetation. Here we attempt to attribute trends in the fractional green vegetation cover to climate vari...

2017
Dongwook W. Ko Dasom Kim Amartuvshin Narantsetseg Sinkyu Kang

Background: Monitoring terrestrial vegetation cover condition is important to evaluate its current condition and to identify potential vulnerabilities. Due to simplicity and low cost, point intercept method has been widely used in evaluating grassland surface and quantifying cover conditions. Field-based digital photography method is gaining popularity for the purpose of cover estimate, as it c...

2016
Nick A. Cutler Olivia M. Shears Richard T. Streeter Andrew J. Dugmore

The factors that influence tephra layer taphonomy are poorly understood, but vegetation cover is likely to play a role in the preservation of terrestrial tephra deposits. The impact of vegetation on tephra layer preservation is important because: 1) the morphology of tephra layers could record key characteristics of past land surfaces and 2) vegetation-driven variability in tephra thickness cou...

2017
Åsa N. Austin Joakim P. Hansen Serena Donadi Johan S. Eklöf

Field surveys often show that high water turbidity limits cover of aquatic vegetation, while many small-scale experiments show that vegetation can reduce turbidity by decreasing water flow, stabilizing sediments, and competing with phytoplankton for nutrients. Here we bridged these two views by exploring the direction and strength of causal relationships between aquatic vegetation and turbidity...

Journal: :caspian journal of environmental sciences 2010
m. jafari z. jafarian jeloudar

the aim of this study was to investigate relationships between soil properties and plant species to determine the most effective factors separating vegetation communities in rineh rangeland. three stratifying variables were selected including slop, aspect and elevation. the study area was partitioned by combining these classes to generate homogenous units. 1m2 quadrates were located at sampling...

2008
Benjamin I. Cook Howard E. Epstein

We investigate the response of a climate system model to two different methods for estimating snow cover fraction. In the control case, snow cover fraction changes gradually with snow depth; in the alternative scenarios (one with prescribed vegetation and one with dynamic vegetation), snow cover fraction initially increases with snow depth almost twice as fast as the control method. In cases wh...

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