نتایج جستجو برای: average of canopy cover diameter
تعداد نتایج: 21187469 فیلتر نتایج به سال:
The protection and improvement of natural resources especially for desert vegetation need a comprehensive recognition of natural resources and relationship on Soil characteristics. One of the most important species growing in sabzevar desert is Stipagrostis pennata and in the current research the relationship between the physicochemical properties of the soils and growth characteristics of the ...
Questions: How do fire frequency, tree canopy cover, and their interactions influence cover of grasses, forbs and understorey woody plants in oak savannas and woodlands? Location: Minnesota, USA. Methods: We measured plant functional group cover and tree canopy cover on permanent plots within a long-term prescribed fire frequency experiment and used hierarchical linear modeling to assess plant ...
this study aims at assessing the impact of land use change (from forest areas to forest parks) on some silvicultural characteristics of stands under recreational land use in boloran natural forest park, kuhdasht. for this purpose, three zones including non-recreation, extensive recreation and intensive recreation regions were chosen. in each zone 30 sample plots in a systematic random design (1...
We examined UV-B radiation flux and its environmental control within and among streams of northern Michigan. UV-B flux was estimated in streams by plastic dosimetry strips, which allow for the simultaneous and repeated in situ measurement of solar radiation. During the summer of 2004, UV-B flux was measured across depth gradients and along longitudinal transects in seven streams, which were cho...
Assessment of forest structure and their spatial patterns are essential for managing and evaluation of forest ecosystems. This study was conducted at the Zagros forests in Kermanshah to evaluate the forest structural characteristics and their spatial distribution. Data was collected from 25 plots (400 m2) in a 100 m × 100 m systematic sampling grid. The spacing between plots was 50 m. In each p...
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....
Risks assessment of forest project implementation in spatial density changes of forest under canopy vegetation using artificial neural network modeling approach Nowadays, environmental risk assessment has been defined as one of the effective in environmental planning and policy making. Considering the position and structure of vegetation on the forest floor, the main role of forest under ca...
the study of the exclosure effects on the vegetation changes undergrazing and non-grazing conditions in the rangeland areas has particularimportance in the rangeland improvement and revivification projects. theresearch was accomplished in semi-steppe khoybilehvar area, from 1999 to2005. vegetation cover was annually measured within fixed plots during transact.the results showed that during nine...
Short-term changes (5 years) in canopy cover, species composition and forage production were studied under protection from grazing and grazed condition in 19 range sites in Fereydan region, Isfahan province. In this study, density, canopy cover and forage production data were obtained from quadrates inside and outside exclosures in the spring of 1983. These parameters were studied again in 1988...
understanding the relationship between root yield and other traits in sugar beet may be a crucial step towards successful breeding of this important crop. path analysis provides a useful method in analyzing the genetic and phenotypic coefficients of correlations. this method is able to effectively unveil direct and indirect effects among traits of interest. in this research, root yield, yield c...
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