نتایج جستجو برای: forests
تعداد نتایج: 39403 فیلتر نتایج به سال:
Do climatic variations and drought magnitude affect large-scale vegetation composition in the Central Zagrosian forests, and to what extent do topographic variables of altitude and aspect play a role in these potential differences? To answer this question, in this research, the flora list of 15 Central Zagros forests was obtained in five plant life forms between the valleys of two rivers, Gerdb...
Increasing urbanisation and industrialisation have led to a dramatic reduction in forest area, and now only culturally protected remnants of natural forests and some new plantations remain in most areas of the north of Iran. To investigate the status of the chemical and physical characteristics of soil under these remnant forests and assess the possible impacts of reforestation on soil properti...
On the basis of the configuration characteristics of man-made forests, the spread model of wireless sensor signal in man-made forests has been simplified according to electromagnetic wave theory and Fermat principle. The man-made forests is decomposed into independent medium with four layers, the spread model is simplified into free space model, attenuation screen model and absorption screen mo...
Airborne light detection and ranging (LiDAR) has been used for forest biomass estimation for the past three decades. The performance of estimation, in particular, has been of great interest. However, the difference in the performance of estimation between stem volume (SV) and total dry biomass (TDB) estimations has been a priority topic. We compared the performances between SV and TDB estimatio...
Globally, mature forests appear to be increasing in biomass density (BD). There is disagreement whether these increases are the result of increases in atmospheric CO2 concentrations or a legacy effect of previous land-use. Recently, it was suggested that a threshold of 450 years should be used to define mature forests and that many forests increasing in BD may be younger than this. However, the...
Highly seasonal rainfall creates a pulse of litterfall in the southern Yucatan peninsula region, with cascading effects on the timing of essential nutrient fluxes, microbial dynamics, and vegetation growth. I investigated whether forest age or a regional environmental gradient related to rainfall has a greater effect on patterns of litterfall in this increasingly human-dominated landscape. Litt...
this research has been carried out with the aim of the determination of the land-use changes of the forests in the protected area of arasbaran. the determination of the changing points and the factors influencing these changes by the use of gis and remote sensing are the main aims of this research. accordingly, the satellite pictures pertaining to the years 1987 and 2005 along with other necess...
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Vertically aligned carbon nanotube (CNT) forests may be used as miniature springs, compliant thermal interfaces, and shock absorbers, and for these and other applications it is vital to understand how to engineer their mechanical properties. Herein is investigated how the diameter and packing density within CNT forests govern their deformation b...
Urban areas are continuously expanding today, extending their influence on an increasingly large proportion of woods and trees located in or nearby urban and urbanizing areas, the so-called urban forests. Although these forests have the potential for significantly improving the quality the urban environment and the well-being of the urban population, data to quantify the extent and characterist...
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