نتایج جستجو برای: ecological indices

تعداد نتایج: 181372  

The arid regions are fragile and sensitive ecological environment and are vulnerable to desertification. This critical area around arid region where desertification occurs determines the ecological stability of the deserts. In order to combat desertification and decreasing its risks, the restoration projects using varieties of plant species were applied that could change the soil properties and...

2014
Linyu Xu Hao Yin Zhaoxue Li Shun Li

As the land ecosystem provides the necessary basic material resources for human development, land ecological security (LES) plays an increasingly important role in sustainable development. Given the degradation of land ecological security under rapid urbanization and the urgent LES requirements of urban populations, a comprehensive evaluation method, named Double Land Ecological Security (DLES)...

Journal: :FEMS microbiology ecology 2003
Tom C J Hill Kerry A Walsh James A Harris Bruce F Moffett

Abstract There are many ecological diversity measures, but their suitability for use with highly diverse bacterial communities is unclear and seldom considered. We assessed a range of species richness and evenness/dominance indices, and the use of species abundance models using samples of bacteria from zinc-contaminated and control soils. Bacteria were assigned to operational taxonomic units (O...

2009
Tayebeh Tabatabaie Fazel Amiri

SUMMARY Operational monitoring of vegetative cover by remote sensing currently involves the utilisation of vegetation indices. Vegetation indices are widely used for assessing and monitoring ecological variables such as vegetation cover, above-ground biomass and leaf area index. This study reviewed and evaluated different vegetation indices for estimating vegetation cover in rangelands in Cente...

Journal: :Environmental monitoring and assessment 2010
Shirish Bhat Jennifer M Jacobs Kirk Hatfield Wendy D Graham

The magnitude, frequency, duration, timing, and rate of change of hydrologic conditions regulate ecological processes in aquatic ecosystems. Conditions are typically characterized using annual-based hydrologic indices derived from daily and/or monthly stream flow data. In this study, we present an alternative approach to identify hydrologic indices based on storm hydrographs. Hydrologic indices...

2006
N. Vlasenko

The paper describes positive and negative aspects of the basic UGS facilities’ impact on the environment using the results of the study of ecologically hazardous factors on the UGS operation areas. On the basis of results of ecological investigations at Russian underground gas storages that have been recently carried out a comprehensive estimation of UGS impact on the environment was given and ...

Drought is one of the main factors of ecological potential stress due to the wide extension of the time scale and impact space. The performance of regional drought monitoring using the meteorological indicators is a challenge due to spatial distribution constraints. In present study, 168 time series images including NDVI and LST indices were used. Integrating these two indices, VSWI was used to...

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