نتایج جستجو برای: vegetation cover 0119

تعداد نتایج: 148663  

Journal: :Environmental management 2006
Steven S Seefeldt D Terrance Booth

Methods that are more cost-effective and objective are needed to detect important vegetation change within acceptable error rates. The objective of this research was to compare visual estimation to three new methods for determining vegetation cover in the sagebrush steppe. Fourteen management units at the US Sheep Experiment Station were identified for study. In each unit, 20 data collection po...

Journal: :caspian journal of environmental sciences 2011
m. jafari sh. baghbani a. tavili m. a. zare chahouki a. malekian

some chemical characteristics of root, shoot and litter of index species such as salsola rigida, artemisia sieberi and stipa barbata commonly used in rangeland development projects were evaluated and compared. chemical properties of soil under and between the above mentioned species were also studied. for this purpose, vegetation types of stipa barbata and artemisia sieberi - salsola rigida wer...

Journal: :journal of rangeland science 2015
amir mirzaei mossivand farshad keivan behjou ehsan zandi esfahan ardavan ghorbani

the aim of this study was to assess the regional effects of fire on the surface cover and forage production of mountainous rangelands of delfan county, lorestan province, iran. the fire took placed in june 2007 with significant effects on the vegetation characteristics in the study area. four fire affected sites were selected for sampling and a close area without fire was considered as control....

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: :Remote Sensing 2016
Yingbin Deng Changshan Wu

Multiple endmember spectral mixture analysis (MESMA) has been widely applied for estimating fractional land covers from remote sensing imagery. MESMA has proven effective in addressing inter-class and intra-class endmember variability by allowing pixel-specific endmember combinations. This method, however, assumes that each land cover type has an equal probability of being included in the model...

Climate is the most important factor of plants distribution in global and regional scale. Understanding the current distribution of vegetation cover and its interaction with climate regularity is important for predicting its future. In order to determine the effective climate factors in plant life-form in Polour rangelands in the Damavand summit (2400 to 4100 m above sea level), Iran, a study w...

2007
Elizabeth A. Allen Robert S. Nowak

As pinyon–juniper (specifically, Pinus monophylla and Juniperus osteosperma) woodlands in the western United States increase in distribution and density, understory growth declines and the occurrence of crown fires increases, leaving mountainsides open to both soil erosion and invasion by exotic species. We examined if the loss in understory cover that occurred with increasing tree cover was re...

Journal: :Brazilian journal of biology = Revista brasleira de biologia 2016
A C M Queiroz C R Ribas

We tested the hypothesis of a negative relationship between vegetation characteristics and ant species richness in a Brazilian open vegetation habitat, called candeial. We set up arboreal pitfalls to sample arboreal ants and measured the following environmental variables, which were used as surrogate of environmental heterogeneity: tree richness, tree density, tree height, circumference at the ...

Journal: :Journal of environmental management 2009
Rachel Hill Catherine Pickering

Experimental trampling trials using a standardized methodology were undertaken in 10 replicate blocks in three vegetation types in an urban reserve in the subtropics of Australia. In each block different intensities of trampling (controls, 10, 25, 50, 100, 150, 200, 250, 300, 400 and 500 passes) were applied, and vegetation parameters were measured pre-trampling, immediately after trampling and...

2004
E B Spurr B Warburton

Stem density, basal area, vegetation cover and vegetation surface area were compared as measures of the proportions of plant species present in North Okarito Forest, South Westland, for use in determining bird preferences for plant species. In general, stem density estimates of the proportions of canopy species were about 10 times lower than basal area estimates. The converse was true for estim...

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