نتایج جستجو برای: forest growth

تعداد نتایج: 915181  

Journal: :caspian journal of environmental sciences 2011
s. mohammadi limaei r. naghdi s. namdari a. e. bonyad

the aim of this study was to determine the optimal cutting cycle in an uneven-aged beech forest in the north of iran. first of all, a logistic growth model was determined for an uneven aged forest. then, the stumpage price was predicted via an autoregressive model. the average stumpage price of beech was derived from actual timber, round wood, fire and pulpwood prices at road side minus the var...

2014
Manette E. Sandor Robin L. Chazdon

Remnant trees, spared from cutting when tropical forests are cleared for agriculture or grazing, act as nuclei of forest regeneration following field abandonment. Previous studies on remnant trees were primarily conducted in active pasture or old fields abandoned in the previous 2-3 years, and focused on structure and species richness of regenerating forest, but not species composition. Our stu...

Journal: :Remote Sensing 2017
David Gwenzi Eileen H. Helmer Xiaolin Zhu Michael A. Lefsky Humfredo Marcano-Vega

Remotely-sensed estimates of forest biomass are usually based on various measurements of canopy height, area, volume or texture, as derived from LiDAR, radar or fine spatial resolution imagery. These measurements are then calibrated to estimates of stand biomass that are primarily based on tree stem diameters. Although humid tropical forest seasonality can have low amplitudes compared with temp...

Journal: :محیط شناسی 0
محمد جواد امیری دانشجوی دکترای جنگلداری دانشگاه تربیت مدرس نور سید غلامعلی جلالی دانشیار گروه جنگلداری دانشکدة منابع طبیعی دانشگاه تربیت مدرس نور عبدالرسول سلمان ماهینی استادیار دانشکدة محیط زیست دانشگاه علوم کشاورزی و منابع طبیعی گرگان سید محسن حسینی دانشیار گروه جنگلداری دانشکدة منابع طبیعی دانشگاه تربیت مدرس نور فرود آذری دهکردی استادیار گروه برنامه ریزی و مدیریت دانشکدة محیط زیست دانشگاه تهران

forest ecosystems that have spent a long time to mature, offer important goods and services to humanity. hence, utilization and exploitation of these resources should be based on careful assessment of their ecological value and potential. ecological land evaluation is an approach based on land quality, vulnerability and potential assessment for different acceptable uses drawing upon related mod...

2003
Jerome K Vanclay

The world is continually changing: the emergence of new technology and new demands for pertinent information pose new challenges and possibilities for forest management. Are forest growth models keeping up with client needs? To remain relevant, modelers need to anticipate client needs, gauge the data needed to satisfy these demands, develop the tools to collect and analyze these data efficientl...

2009
F. HARVEY POUGH ELLEN M. SMITH DONALD H. RHODES

Pough, F.H., Smith, E.M., Rhodes, D.H. and Collazo, A., 1987. The abundance of salamanders in forest stands with different histories ofdisturbance. For. Ecol. Manage., 20: 1-9. Because of the importance of salamanders in forest food chains, the effects of forest management practices on populations of these animals warrant consideration. We compared the numbers and activity patterns of salamande...

2004
Claudia Alvarez-Aquino Guadalupe Williams-Linera Adrian C. Newton

The cloud forests of Mexico have been degraded and severely fragmented, and urgently require restoration. However, progress with restoration has been constrained by a lack of information concerning the seedling ecology of native tree species. An experiment was therefore conducted to assess the influence of different environmental factors on the seedling survival and growth of four native tree s...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تحصیلات تکمیلی صنعتی کرمان - دانشکده برق و کامپیوتر 1390

عملکردهای زیستی پروتئین ها به واکنش های شیمیایی آنها با محیط پیرامون و سایر پروتئین ها بستگی دارد. به عبارت دیگر، ساختار سه بعدی و نحوه تاخوردن اجزای پروتئین ها در فضا، چگونگی این تعاملات را تعیین می کند. تشخیص صحیح الگوی تاخوردگی پروتئین با استفاده از اطلاعات استخراج شده از توالی آن، یکی از مسائل پیچیده و بحث برانگیز در زمینه بیوانفورماتیک می باشد. در این پایان نامه، سه روش نوین مبتنی بر الگور...

2013
Feifei Zhu Muneoki Yoh Frank S. Gilliam Xiankai Lu Jiangming Mo

Elevated nitrogen (N) deposition to tropical forests may accelerate ecosystem phosphorus (P) limitation. This study examined responses of fine root biomass, nutrient concentrations, and acid phosphatase activity (APA) of bulk soil to five years of N and P additions in one old-growth and two younger lowland tropical forests in southern China. The old-growth forest had higher N capital than the t...

2005
Xiaowei Yu Juha Hyyppä Harri Kaartinen Hannu Hyyppä Matti Maltamo Petri Rönnholm

It is well known that characteristics of individual trees, such as tree height, biomass and crown area, can be derived from airborne laser scanning (ALS) and that heights for individual trees can be obtained with an accuracy of 0.5 to 1.5 m. However, the ability to measure the growth of individual trees using ALS has not been documented. This paper reports multi-temporal laser surveys conducted...

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