نتایج جستجو برای: mixed and natural stands

تعداد نتایج: 16917246  

2002
J. Steven Meadows

INTRODUCTION Silviculture for the production of high-quality timber in southern bottomland hardwood forests involves the application of environmentally sound practices in order to enhance the growth and quality of both individual trees and stands. To accomplish this purpose, silvicultural practices are typically used to regulate stand density, species composition, and stem quality to promote th...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه ارومیه - دانشکده کشاورزی 1393

چکیده کنه تارتن دو لکه ای tetranychus urticae koch یکی از چندخوارترین آفات شناخته شده محصولات کشاورزی دنیا به حساب می آید. در این بررسی جمعیت تخم و مراحل فعال این کنه در شرایط آلودگی طبیعی و مصنوعی در برگ های 8 رقم لوبیا در سال 1392 در گلخانه و مزرعه تحقیقاتی دانشکده کشاورزی دانشگاه ارومیه موردمطالعه قرار گرفت. آزمایش به صورت طرح کاملاً تصادفی برای شرایط مزرعه در10 تکرار و برای شرایط گلخانه ای...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شهید باهنر کرمان 1388

copper extraction from heap 3 low grade ore at sarchechmeh is limited due to its mixed composition (copper oxide and sulphide minerals). changing this heap to a bioheap could improve the copper recovery.

2012
David S. Dyson Longleaf Pine

Longleaf pine once was present on 90 million acres of the southern landscape, ranging from coastal Virginia to east Texas and from central Florida to the mountains of Alabama. On nearly two-thirds of that area, longleaf pine grew in nearly pure (single-species) stands maintained by frequent, low-intensity surface fires of both natural and human origin. The remaining one-third of that area was s...

2007
Charles G. Tauer Shiqin Xu C. Dana Nelson James M. Guldin

-Since the 1950s the existence of natural hybrids between shortleaf pine and loblolly pine has been recognized and reported in the literature. In a range-wide study of isoenzyme diversity in shortleaf pine. we found 16 percent of the trees from western populations were hybrids. based on the isocitrate dehydrogenase (IDH) locus. In stands thought to be pure shortleaf pine in west central Arkansa...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شهید مدنی آذربایجان - دانشکده ادبیات و زبانهای خارجی 1389

according to coates’s (2004, as cited in zhang, 2010) definition of "conversational dominance" (p.111), it refers to the phenomenon of a speaker dominating others in interaction. specifically, it means how a speaker makes use of certain strategies to get the floor and maintain the floor. thus, the amount of talk is the main measurement for the dominance of the conversation. whether a speaker do...

2017
Justin L. Hart Lauren E. Cox

We propose a conceptual framework for the development of closed canopy oak (Quercus) stands that incorporates the influence of intermediate-severity canopy disturbance events, provides for the possibility of multiple developmental pathways, and does not narrowly define an endpoint given the stochastic nature of natural disturbances. The proposed model differs from the current oak stand developm...

Journal: :Plant biology 2014
M del Río G Schütze H Pretzsch

Facilitation, reduced competition or increased competition can arise in mixed stands and become essential to the performance of these stands when compared to pure stands. Facilitation and over-yielding are widely held to prevail on poor sites, whereas neutral interactions or competition, leading to under-yielding of mixed versus pure stands, can occur on fertile sites. While previous studies ha...

2007
Thomas Knoke Bernd Stimm Christian Ammer Martin Moog

To stimulate an economically oriented discussion on mixed forest management, this paper considers economic implications of mixed investments of pure stands of the Norway spruce (Picea abies (L.) Karst.) and the European beech (Fagus sylvatica L.) on a methodological basis. It is well known that the classical economic calculus leads to an overwhelming financial superiority of single species coni...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان 1390

cement is an essential ingredient in the concrete buildings. for production of cement considerable amount of fossil fuel and electrical energy is consumed. on the other hand for generating one tone of portland cement, nearly one ton of carbon dioxide is released. it shows that 7 percent of the total released carbon dioxide in the world relates to the cement industry. considering ecological issu...

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