نتایج جستجو برای: arid flora and vegetation

تعداد نتایج: 16844048  

Journal: :desert 0
h.r. keshtkar msc. graduate, university of tehran, karaj, iran h. azarnivand professor, faculty of natural resources, university of tehran, karaj, iran h. arzani professor, faculty of natural resources, university of tehran, karaj, iran s.k. alavipanah professor, faculty of geography, university of tehran, tehran, iran f. mellati instructor, faculty of environment and natural resources, ferdowsi university, mashhad, iran

land cover is one of basic data layers in geographic information system for physical planning and environmentalmonitoring. digital image classification is generally performed to produce land cover maps from remote sensing data,particularly for large areas. in the present study the multispectral image from irs liss-iii image along with ancillary datasuch as vegetation indices, principal componen...

Journal: :Remote Sensing 2016
Dan J. Krofcheck Marcy E. Litvak Christopher D. Lippitt Amy Neuenschwander

The rapid and accurate assessment of above ground biomass (AGB) of woody vegetation is a critical component of climate mitigation strategies, land management practices and process-based models of ecosystem function. This is especially true of semi-arid ecosystems, where the high variability in precipitation and disturbance regimes can have dramatic impacts on the global carbon budget by rapidly...

Journal: :Records of the Western Australian Museum, Supplement 2004

2012
Edson Gandiwa

The objective of this study was to investigate the effects of repeated dry season annual hot fires on woody plants in a semi-arid southern African savanna in Zimbabwe. Parts of the National University of Science and Technology (NUST) research fields in Bulawayo, Zimbabwe have been burnt annually in the dry season between 1994 and 2003 in order to control bush encroachment. The present study was...

2007
Xianwei Wang Hongjie Xie Huade Guan Xiaobing Zhou

r a 200 .022 : +1 210 [email protected] Summary Surface representation of the root-zone soil moisture is investigated so that feasibility of using optical remote sensing techniques to indirectly map root-zone soil moisture is assessed. Specifically, covariation of root-zone soil moisture with the normalized difference of vegetation index (NDVI) from Moderate Resolution Imaging Spectroradiometer (MODIS) ...

2010
Yuhong He Amy Mui

Remote sensing imagery is being used intensively to estimate the biochemical content of vegetation (e.g., chlorophyll, nitrogen, and lignin) at the leaf level. As a result of our need for vegetation biochemical information and our increasing ability to obtain canopy spectral data, a few techniques have been explored to scale leaf-level biochemical content to the canopy level for forests and cro...

Journal: :Papers and Proceedings of the Royal Society of Tasmania 1995

2007
Paolo D’Odorico Kelly Caylor Gregory S. Okin Todd M. Scanlon

[1] Soil moisture is the environmental variable synthesizing the effect of climate, soil, and vegetation on the dynamics of water-limited ecosystems. Unlike abiotic factors (e.g., soil texture and rainfall regime), the control exerted by vegetation composition and structure on soil moisture variability remains poorly understood. A number of field studies in dryland landscapes have found higher ...

2016
Javier Marcello Francisco Eugenio Ulises Perdomo Anabella Medina Machín

The precise mapping of vegetation covers in semi-arid areas is a complex task as this type of environment consists of sparse vegetation mainly composed of small shrubs. The launch of high resolution satellites, with additional spectral bands and the ability to alter the viewing angle, offers a useful technology to focus on this objective. In this context, atmospheric correction is a fundamental...

2016
Laleh PARVIZ

The aim of this research was to determine the effective drought indices such as NDVI, VCI, EVI, TVX, VTCI, VHI, TCI and NVSWI based on some criteria. The satellite-based drought indices have different data from vegetation and temperature conditions. Linear and trend analysis showed that satellite-based drought indices based on vegetation condition were not more efficient indices such as NDVI an...

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