Fodder trees and shrubs are crucial sources of animal feed in Sudan, particularly in arid and semi-arid areas. This is because they can fill up the feed gaps in the summer period when grassland growth is limited due to unfavorable weather conditions. The study was conducted in Elnour forest-southeastern Sudan in 2015, which is dominated by Acacia seyal. The objectives of this study were to esti...

We present runt pruning, a new clustering method that attempts to find modes of a density by analyzing the minimal spanning tree of a sample. The method exploits the connection between the minimal spanning tree and nearest neighbor density estimation. It does not rely on assumptions about the specific form of the data density (e.g., normal mixture) or about the geometric shapes of the clusters,...

Where one or a few tree species reach local high abundance, different ecological factors may variously facilitate or hinder their regeneration. Plant pathogens are thought to be one of those possible agents which drive intraspecific density-dependent mortality of tree seedlings in tropical forests. Experimental evidence for this is scarce, however. In an African rain forest at Korup, we manipul...

For a density f on R, a high-density cluster is any connected component of {x : f(x) ≥ λ}, for some λ > 0. The set of all high-density clusters form a hierarchy called the cluster tree of f . We present a procedure for estimating the cluster tree given samples from f . We give finite-sample convergence rates for our algorithm, as well as lower bounds on the sample complexity of this estimation ...

Rates and spatial patterns of tree mortality are predicted to change during forest structural development. In young forests, mortality should be primarily density dependent due to competition for light, leading to an increasingly spatially uniform pattern of surviving trees. In contrast, mortality in old-growth forests should be primarily caused by contagious and spatially autocorrelated agents...

A study was carried out at the treeline ecotone (3,730m-3,950m asl) of Langtang National Park in central Nepal with an aim to document the impact of climatic warming on ecological chracteristics. Three sampling sites were selected at Chaurikharka and Lauribina, where no serious anthropogenic pressure was noticed. The nearest meteorological station has records of climatic warming in recent years...

In forests, the growth and productivity of individual trees stands as a whole are regulated by stand density among other factors, because access to vital resources is limited competition between trees. On 18 experimental plots Scots pine (Pinus sylvestris L.) planted with 500–128,000 trees/ha in south taiga (Middle Siberia), interactions density, tree- stand-scale productivity, tree-ring parame...

Wind routinely topples trees during storms, and the likelihood that a tree is toppled depends critically on its allometry. Yet none of the existing theories to explain tree allometry consider wind drag on tree canopies. Since leaf area index in crowded, self-thinning stands is independent of stand density, the drag force per unit land can also be assumed to be independent of stand density, with...