Theoretical studies of process flexibility designs had mostly focused on average-case analysis. In this paper, we take a different approach by studying process flexibility designs from a worst-case point of view. To study the worst-case performances, we introduce the so-called plant cover index, an index defined by a constrained bipartite vertex cover problem associated with a given flexibility...

The performance of many desert plant species in North America may decline with the warmer and drier conditions predicted by climate change models, thereby accelerating land degradation and reducing ecosystem productivity. We paired repeat measurements of plant canopy cover with climate at multiple sites across the Chihuahuan Desert over the last century to determine which plant species and func...

An intense debate exists on the effects of post-fire salvage logging on plant community regeneration, but scant data are available derived from experimental studies. We analyzed the effects of salvage logging on plant community regeneration in terms of species richness, diversity, cover, and composition by experimentally managing a burnt forest on a Mediterranean mountain (Sierra Nevada, S Spai...

Emergent or submergent macrophytes can enhance the survival of Anopheles larvae by providing favorable microhabitat and refuge from predation. The relationships among the amount of aquatic macrophyte cover, the density of Gambusia affinis, and survivorship of Anopheles freeborni larvae were tested experimentally. Larval survivorship was positively related to amount of plant cover and negatively...

Two integrations of a global general circulation model, differing only in the prescribed surface albedo in the Sahara, show that an increase in albedo resulting from a decrease in plant cover causes a decrease in rainfall. Thus any tendency for plant cover to decrease would be reinforced by a decrease in rainfall, and could initiate or perpetuate a drought.

the purpose of this research is investigation of relationship between vegetation cover and soil characteristics and determination of the most important soil factor that effects on quantity variations and kinds of vegetation cover in the study area. the study area is located in west of tehran province and south eastern of hashtgerd, next to najm-abad village. after field study, the index vegetat...

Excessive herbivory can have transformative effects on forest understory vegetation, converting diverse communities into depauperate ones, often with increased abundance of non-native plants. White-tailed deer are a problematic herbivore throughout much of eastern North America and alter forest understory community structure. Reducing (by culling) or eliminating (by fencing) deer herbivory is e...

Plant biomass is an important factor for determining arid and semi-aridrangelands capacity. Due to the lack of proper and annual sampling of rangelands, there areno suitable data to determine biomass, range condition and proper range managementoperations. Plant biomass is one of the measurable attributes that can be assessed inrangeland studies. Since the clip and weight method is destructive a...

We assessed plant interspaces in July 2007 using continuous line intercepts in twice-replicated pastures of northern mixed-grass prairie with contrasting grazing treatments: 1) long-term (25 yr) heavily grazed, dominated by the bunchgrass blue grama (Bouteloua gracilis), and 2) ungrazed, dominated by the rhizomatous grass western wheatgrass (Pascopyrum smithii). The number of plant interspaces ...