نتایج جستجو برای: irans forests
تعداد نتایج: 39516 فیلتر نتایج به سال:
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...
An example of the possible use of selected forest-stand based indicators for evaluation of conservation status was shown in case of the Natura 2000 forest habitats of Slovenia, and the potential threats to habitat types were identified. Using the existing forest-management system, and two levels of ICP Forests monitoring as sources of data on the size of habitat, tree composition, developmental...
Random forests are one type of the most effective ensemble learning methods. In spite of their sound empirical performance, the study on their theoretical properties has been left far behind. Recently, several random forests variants with nice theoretical basis have been proposed, but they all suffer from poor empirical performance. In this paper, we propose a Bernoulli random forests model (BR...
Elevated nitrogen (N) deposition may constrain soil phosphorus (P) and base cation availability in tropical forests, for which limited evidence have yet been available. In this study, we reported responses of soil inorganic nutrients to full factorial N and P treatments in three tropical forests different in initial soil N status (N-saturated old-growth forest and two less-N-rich younger forest...
Carbon stock is an important indicator of cumulative ecosystem productivity. Using this indicator, and based on field sampling data, this paper compared the long-term difference in carbon stocks between aerial seeding (AS) and natural regeneration (NR) forests of Pinus massoniana in sub-tropic forests, China, in order to assess the effectiveness of AS in a highly degraded forest landscape. The ...
the support of agricultural sector is adopted in various countries of the globe through different means and mostly with the aims such as increasing farmers incomes, protecting domestic products, ending dependence (on foreign goods), augmenting employment and reducing poverty. this paper tries to survey the support policies in agricultural sector in different countries as far as their components...
Over the last two and half decades, strong evidence showed that the terrestrial ecosystems are acting as a net sink for atmospheric carbon. However the spatial and temporal patterns of variation in the sink are not well known. In this study, we examined latitudinal patterns of interannual variability (IAV) in net ecosystem exchange (NEE) of CO2 based on 163 site-years of eddy covariance data, f...
Mr. GREEN of Wisconsin. Mr. Chairman, I submit the following resolutions for the RECORD. Whereas, our National Forests were established in the 1920’s for multiple use including soil and water protection, recreation, and timber production, and; Whereas, harvesting is an integral component of multiple-use management of forest lands, and; Whereas, it is not in the best interest of sustainable ecos...
Old-growth forests are valuable sources of ecological, conservation, and management information, yet these ecosystems have received little study in New England, due in large part to their regional scarcity. To increase our understanding of the structures and processes common in these rare forests, we studied the abundance of downed coarse woody debris (CWD) and snags and live-tree size-class di...
In this study latent heat flux (λE) measurements made at 65 boreal and arctic eddy-covariance (EC) sites were analyses by using the Penman-Monteith equation. Sites were stratified into nine different ecosystem types: harvested and burnt forest areas, pine forests, spruce or fir forests, Douglas-fir forests, broadleaf deciduous forests, larch forests, wetlands, tundra and natural grasslands. The...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید