We take a new look at the multicut problem in trees through the eyes of the vertex cover problem. This connection, together with other techniques that we develop, allows us to significantly improve the O(k) upper bound on the kernel size for multicut, given by Bousquet et al., to O(k). We exploit this connection further to present a parameterized algorithm for multicut that runs in time O∗(ρk),...

Climate and land cover change are driving a major reorganization of terrestrial biotic communities in tropical ecosystems. In an effort to understand how biodiversity patterns in the tropics will respond to individual and combined effects of these two drivers of environmental change, we use species distribution models (SDMs) calibrated for recent climate and land cover variables and projected t...

Plant cover is a fundamental feature of many coastal marine and terrestrial systems and controls the structure of associated animal communities. Both natural and human-mediated changes in plant cover influence abiotic sediment properties and thus have cascading impacts on the biotic community. Using clipping (structural) and light (shading) manipulations in two salt marsh vegetation zones (one ...

in arid and semi-arid rangelands, grazing as one of the natural or human induced processes has direct and indirect effects on structure and dynamics of plant community and ecosystems. a study was done to analyze the effects of grazing on plant species diversity and plant functional types‘ (pfts) diversity of arid and semi-arid rangelands. we analyzed plant richness and diversity data from 75 sa...

study of soil and plant relationships is nessesery for ecological- based and appropriate management. the objective of this study is to determine the influence of edaphic properties on haloxylon persicum growth and also, indentifing growth limiting soil properties for saxaul. the study was performed through the stratified random sampling and 3 sites were selected as follow: planted strong saxaul...

this research was conducted to compare plant functional types (pft) and traits in an old-field (abandoned for 28 years) and a control site, in the baharkish rangelands, quchan, iran. in the both sites, 40 randomized quadrates were established. floristic list, frequency, canopy cover and 20 vegetative, phenological and morphological plant traits were measured for all plant species, within each q...

Arbuscular mycorrhizal fungi (AMF) are expected to be one of the key drivers determining the diversity of natural plant communities, especially in nutrient-poor and dry habitats. Several previous studies have explored the importance of AMF for the composition of plant communities in various types of habitats. Surprisingly, studies of the role of AMF in nutrient-poor dry grassland communities do...

Quantification of plant litter cover on the soil surface is necessary in both agricultural and natural systems because the presence of litter influences the flow of nutrients, carbon, water, and energy in terrestrial ecosystems. Although remote sensing methods for measuring plant litter cover provide both a wider area of coverage and a more objective estimate of the spatial variability of litte...

A novel method for measuring plant-plant interactions in undisturbed semi-natural and natural plant communities where it is difficult to distinguish individual plants is discussed. It is assumed that the ecological success of the different plant species in the plant community may be adequately measured by plant cover and vertical density (a measure that is correlated to the 3-dimensional space ...