نتایج جستجو برای: semi steppe rangelands

تعداد نتایج: 147987  

Journal: :مرتع و آبخیزداری 0
زهرا نیکبخت دانشجوی کارشناسی ارشد مرتع داری، گروه مرتع و آبخیزداری، دانشگاه فردوسی مشهد، ایران محمد فرزام دانشیار؛ گروه مرتع و آبخیزداری، دانشگاه فردوسی مشهد، ایران. محمد خواجه حسینی دانشیار، گروه زراعت، دانشگاه فردوسی مشهد، ایران حمید اجتهادی استاد، گروه زیست شناسی، دانشگاه فردوسی مشهد، ایران

the study of soil seed bank provides useful information on management and restoration of natural ecosystems. in the arid environments, some perennial plants may cause accumulation of seed bank under their canopy, thereby protecting them against the livestock herbivory and the other environmental factors. this study was conducted with objective to investigate effect of perennial plants on densit...

Journal: :Plant and Soil 2022

We assessed changes in soils and vegetation associated with different plant life forms increasing grazing intensity (GI) a subhumid grassland of Patagonia (Argentina), vast portions these grass steppes degraded states. reconstructed the historic GI gradient study sites characterised cover. sampled soil beneath patches shrub their bare interspaces, as well height hummocks thickness superficial h...

Journal: :Environmental management 2006
Steven S Seefeldt D Terrance Booth

Methods that are more cost-effective and objective are needed to detect important vegetation change within acceptable error rates. The objective of this research was to compare visual estimation to three new methods for determining vegetation cover in the sagebrush steppe. Fourteen management units at the US Sheep Experiment Station were identified for study. In each unit, 20 data collection po...

Journal: :journal of rangeland science 0
jalil ahmadi ferdowsi university of iran mohammad farzam ferdowsi university of mashhad amir lagzian ferdowsi university of mashhad

fire is one of the incorporate vegetation management practices for grasslands and semi-arid rangelands. it may affect symbiotic relationship between range plants and mycorrhiza. accordingly, this research was aimed to investigate the effects of a spring prescribed fire on the symbiotic relationships between mycorrhiza and 6 plant species. the study was conducted in a semi-arid steppe rangeland ...

2012
Ping Zhang Shiping Chen Wenli Zhang Haixia Miao Jiquan Chen Xingguo Han Guanghui Lin

Aims Ecosystem carbon models often require accurate net ecosystem exchange of CO2 (NEE) light-response parameters, which can be derived from the Michaelis–Menten equation. These parameters include maximum net ecosystem exchange (NEEmax), apparent quantum use efficiency (a) and daytime ecosystem respiration rate (Re). However, little is known about the effects of land conversion between steppe a...

1999
Charlotte Boyd Roger Blench David Bourn Liz Drake Peter Stevenson

From the perspective of local livelihoods this paper explores the complex interactions between wildlife, livestock and people, and options for integrated wildlife and livestock management in the semi-arid rangelands of eastern Africa. The paper draws on the sustainable livelihoods approach which explicitly considers whether households have access to the assets required to engage in an activity,...

2011
Keith T. Weber

Correcting satellite imagery for atmospheric effects is a common procedure today. Indeed there are many techniques and software applications that offer atmospheric correction processes. This study compared several techniques (apparent reflectance, dark-object subtraction, Cos(t), and the full cost model) in both Idrisi and ENVI software to determine the level of similarity between resulting ima...

2004
Thomas A. Monaco Douglas A. Johnson Jay B. Norton Jeanette M. Norton Thomas A. Jones

Cheatgrass (Bromus tectorum L.) is an invasive annual grass that increases wildfire frequency, degrades native ecosystems, and threatens agriculture across vast areas of the Western United States. This research examines how cheatgrass invasion may alter physical and biological properties of soils. Proliferation of very fine roots and high production of low-quality litter by cheatgrass increases...

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