نتایج جستجو برای: hyrcanain forests
تعداد نتایج: 39403 فیلتر نتایج به سال:
In this paper we study random forests through their connection with a new framework of adaptive nearest neighbor methods. We first introduce a concept of potential nearest neighbors (k-PNN’s) and show that random forests can be seen as adaptively weighted k-PNN methods. Various aspects of random forests are then studied from this perspective. We investigate the effect of terminal node sizes and...
The world's forests influence climate through physical, chemical, and biological processes that affect planetary energetics, the hydrologic cycle, and atmospheric composition. These complex and nonlinear forest-atmosphere interactions can dampen or amplify anthropogenic climate change. Tropical, temperate, and boreal reforestation and afforestation attenuate global warming through carbon seques...
Random forests are known to be good for data mining of classification tasks, because random forests are robust for datasets having insufficient information possibly with some errors. But applying random forests blindly may not produce good results, and a dataset in the domain of rotogravure printing is one of such datasets. Hence, in this paper, some best classification accuracy based on clever...
The prevalence of Corona disease as one of the most critical infectious diseases has increased the risks of food security in different parts of the world. Local communities, especially in rural areas, are highly dependent on natural resource-based ecosystem service strategies to manage global food security and meet livelihood needs. Forests and pastures can also provide goods and servic...
Remnant forests in urban areas provide vital ecosystem services but are susceptible to many human activities including heavy metal emissions. In this study, we collected 192 samples of mineral soils at depths of 0–3, 3–13 and 13–23 cm in 16 remnant forests (eight natural forests and eight plantation forests) in the urbanized Pearl River Delta, China. We assessed the potential risks of soil Cu, ...
The potential influence of diversity on ecosystem structure and function remains a topic of significant debate, especially for tropical forests where diversity can range widely. We used Center for Tropical Forest Science (CTFS) methodology to establish forest dynamics plots in montane wet forest and lowland dry forest on Hawai'i Island. We compared the species diversity, tree density, basal are...
گونه .phyllanthus tenellus roxb به عنوان گزارش جدید، از غرب مازندران نام برده می شود، این گونه به صورت بومی شده در اغلب مناطق کم ارتفاع و در حاشیه باغ ها و مزارع دیده شده و به علت برخورداری از برگ های بیضی شکل با آرایش غیر مارپیچی که بیشتر دورج به نظر رسیده، همراه با گلهای بسیار کوچک در کنار دمبرگ ها شناخته می شود.
in the present study, randomly amplified polymorphic dna (rapd) markers were used to analyze the genetic diversity in 20 varieties of philodendron. the polymerase chain reaction was performed with 60 rapd primers, out of which 21 primers showed clear amplification as well as more polymorphism. in total, 354 scorable rapd loci with 348 polymorphic bands (98%) were observed. percentages of polymo...
In the present study, the aboveground biomass of the understorey vegetation of boreal coniferous forests was modelled according to the percentage cover. A total of 224 observations from 22 stands in upland forests and 195 observations from 14 different studies in peatland forests were utilized for the present analyses. The relationships between biomass and percentage cover can be used in ecosys...
There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increas...
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