نتایج جستجو برای: density of forbs

تعداد نتایج: 21193008  

2004
MARCELO STERNBERG SHUNLI L. YU

This study investigated the effects of microhabitat characteristics on soil seed bank structure, regeneration strategies, and plant composition in a Mediterranean coastal sand dune in Israel. Three different microhabitats were selected: (a) open patches between shrubs, (b) shrub understorey, and (c) open, disturbed patches in pedestrian trails. In each microhabitat two types of sampling plots w...

Abstract: The aim of this study is investigating the changes of macro elements in soil and vegetation based on the different life form with changes in elevation. For this purpose, soil and vegetation sampling was performed in 13 places in the elevation gradient of 300 to 3300 meters in 2016. In each site were placed three transects of 100 meters with 50 meters distance from each other and along...

2017
Victoria Nuzzo Andrea Dávalos Bernd Blossey

Excessive herbivory can have transformative effects on forest understory vegetation, converting diverse communities into depauperate ones, often with increased abundance of non-native plants. White-tailed deer are a problematic herbivore throughout much of eastern North America and alter forest understory community structure. Reducing (by culling) or eliminating (by fencing) deer herbivory is e...

Journal: :international journal of nano dimension 0
s. jalili department of chemistry, k. n. toosi university of technology,tehran, iran. computational physical sciences research laboratory, department of nano-science, institute for studies in theoretical physics and mathematics (ipm),tehran, iran r. vaziri department of chemistry, k. n. toosi university of technology,tehran, iran.

first principle calculations were performed using density functional theory within the local spin density approximation (lsda) to understand the electronic properties of au(100)+tbt system and compare the results with au(100) and bulk au properties. band structure, the total dos and charge density for these materials are calculated. we found that the homo for au(100)+tbt becomes broader than au...

Journal: :Journal of environmental management 2002
Dale G Brockway Richard G Gatewood Randi B Paris

Although the distribution and structure of pinyon-juiper woodlands in the southwestern United States are thought to be the result of historic fluctuations in regional climatic conditions, more recent increases in the areal extent, tree density, soil erosion rates and loss of understory plant diversity are attributed to heavy grazing by domestic livestock and interruption of the natural fire reg...

Ali Ashraf Jafari Hossein Arzani Mohammad Jafari Sedigheh Zare Kia Seyyed Akbar Javadi

This study aims to assess the effect of grazing intensity on vegetation structure, soil nutrient concentrations and soil physical properties. The study was carried out in steppe rangelands of Saveh, Markazi province, Iran. Four sites with four grazing intensities including very high, high, moderate and non-grazed with the same ecological conditions were selected. To study various vegetation and...

Journal: :مرتع و آبخیزداری 0
جابر شریفی عضو هیت علمی مرکز تحقیقات کشاورزی و منابع طبیعی استان اردبیل ایران. مرتضی اکبرزاده استادیار پژوهشی بخش تحقیقات مرتع مؤسسه تحقیقات جنگل ها ¬و مراتع کشور، ایران.

a major part of the rangelands of iran are located in arid and semi-arid regions. in this climate, rainfall fluctuation is an important factor which affects vegetation and forage production. in dry years that rainfall decreases, surface vegetation and forage production is damaged. this study was conducted on semi-steppic rangelands of ardebil over nine years (1999-2007), to study of vegetation ...

2015
Alrun Siebenkäs Jens Schumacher Christiane Roscher

Functional traits are often used as species-specific mean trait values in comparative plant ecology or trait-based predictions of ecosystem processes, assuming that interspecific differences are greater than intraspecific trait variation and that trait-based ranking of species is consistent across environments. Although this assumption is increasingly challenged, there is a lack of knowledge re...

Journal: :Ecological applications : a publication of the Ecological Society of America 2007
Matthew J Rinella Monica L Pokorny Romdhane Rekaya

The importance of species richness for repelling exotic plant invasions varies from ecosystem to ecosystem. Thus, in order to prioritize conservation objectives, it is critical to identify those ecosystems where decreasing richness will most greatly magnify invasion risks. Our goal was to determine if invasion risks greatly increase in response to common reductions in grassland species richness...

2017
Dan L. Campbell James Evans DAN L. CAMPBELL

Principal methods being used to alleviate browsing damage to Douglas-fir (Pseudotsuga menziesii) seedlings by black-tailed deer (Odocoileus hemionus columbianus) in the Pacific Northwest are animal repellents applied to foilage and plastic mesh cylinders around individual seedlings. As an alternate method, we demonstrated that prompt establishment of highly palatable native forbs reduced summer...

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