نتایج جستجو برای: vegetation cover

تعداد نتایج: 148562  

2007
XINYU ZHENG ELFATIH A. B. ELTAHIR Ralph M. Parsons

The focus of this paper is the role of meridional distribution of vegetation in the dynamics of monsoons and rainfall over West Africa. A moist zonally symmetric atmospheric model coupled with a simple land surface scheme is developed to investigate these processes. Four primary experiments have been carried out to examine the sensitivity of West African monsoons to perturbations in the meridio...

2003
D. L. PETERSON

This study assesses the ability of multitemporal Landsat Thematic Mapper (TM) data and the normalized diVerence vegetation index (NDVI) to spectrally separate grazed cool season and warm season grassland cover types in Douglas County, Kansas. Biophysical data collected during the summer of 1997 suggest that diVerences in the per cent of total living vegetation cover, per cent of senescent veget...

علیرضا امینی حاجی‌ آبادی, , جمال ‌الدین خواجه دین, , سیدعلی میرمحمدی میبدی, ,

A number of halophytic species as Salicornia europea, Halocnemum strobilaceum, Aeluropus lagopoides, and Aeluropus littoralis were found to occupy a significant portion of the total vegetation of the surrounding area at the Zayande-Roud inlet to Gavkhoony wetland. However, their ecological demands and bioenvironmental factors by which vegetation community composition has been affected is not un...

2017
David M. Bell Andrew N. Gray

While ecological succession shapes contemporary forest structure and dynamics, other factors like forest structure (dense vs. sparse canopies) and climate may alter structural trajectories. To assess potential sources of variation in structural trajectories, we examined proportional biomass change for a regionally dominant tree species, Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), across...

2016
Kim André Vanselow Cyrus Samimi Siegmar-W. Breckle Stefan Lötters

We edited, redrew, and evaluated four unpublished historical vegetation maps of the Western Pamirs (Tajikistan) by the Soviet geobotanist Okmir E. Agakhanjanz. These maps cover an area of 5,188 km2 and date from 1958 to 1960. The purpose of this article is to make the historic vegetation data available to the scientific community and thus preserve a hitherto non available and up to now neglecte...

2016
Haixin Liu Anbing Zhang Tao Jiang Haitao Lv Xinxia Liu Hefeng Wang

This study proposes a modified vegetation-dependent temperature-vegetation dryness index (TVDI) model for analyzing regional drought disasters in the Beijing-Tianjin-Hebei Metropolitan Region (BTHMR) of China. First, MODIS monthly normalized difference vegetation index (NDVI), land surface temperature (LST) data and land use/cover data (Land cover type2) were pre-processed as a consistent big d...

2013
Jie Wang Hiroshi Ishidaira Wenchao Sun Shaowei Ning

Suspended sediment concentration of a river can provide very important perspective on erosion or soil loss of one river basin ecosystem. The changes of land use and land cover, such as deforestation or afforestation, affect sediment yield process of a catchment through changing the hydrological cycle of the area. A sediment rating curve can describe the average relation between discharge and su...

Journal: :Ecology 2008
James B Heffernan

Historically, desert drainages of the American southwest supported productive riverine wetlands (ciénegas). Region-wide erosion of ciénegas during the late 19th and early 20th century dramatically reduced the abundance of these ecosystems, but recent reestablishment of wetlands in Sycamore Creek, Arizona, USA, provides an opportunity to evaluate the mechanisms underlying wetland development. A ...

Journal: :Journal of the American Mosquito Control Association 1997
P A Turner W J Streever

Knowledge of oviposition sites selected by wetland mosquitoes could improve mosquito control and guide wetland rehabilitation practices to avoid creating or exacerbating a mosquito problem. Two studies that enumerated Aedes vigilax eggshells found in salt marsh soil on the western portion of Kooragang Island in New South Wales, Australia, allowed an evaluation of oviposition sites. In one study...

1997
Michael A. Patten

I conducted small-mammal trapping surveys on a desert scrub restoration site in Palm Springs, California, to document concomitant recovery of the rodent community. These surveys were conducted following quantitative vegetation sampling efforts that indicated that a predefined successful restoration criterion of 15% total shrub cover had been met throughout most of the area. But shrub cover, nat...

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