This thesis presents a new class of surface patches for the creation of sculptured surfaces in mechanical engineering applications of computer aided design. Ideas from differential geometry are used to create principal patches whose edges are lines of curvature. This is done by ensuring that the sides obey two equations called the frame matching and position matching conditions. It is shown tha...

In the semi-arid rangelands of north central Kenya, the abundance of grasses has declined over recent decades. Concomitantly, the native succulent herb Sansevieria volkensii has greatly proliferated in many areas. Landscape structure has thus shifted from contiguous herbaceous cover to large, dense stands of S. volkensii with interpatches of bare or sparsely vegetated ground. Local pastoralists...

Impacts of disturbance history on forest carbon stocks and fluxes: Merging satellite disturbance mapping with forest inventory data in a carbon cycle model framework" (2014). NASA Publications. Paper 163. a b s t r a c t a r t i c l e i n f o Forest carbon stocks and fluxes are highly dynamic following stand-clearing disturbances from severe fire and harvest and this presents a significant chal...

Burned landscapes present several challenges to quantifying landscape carbon balance. Fire scars are composed of a mosaic of patches that differ in burn severity, which may influence postfire carbon budgets through damage to vegetation and carbon stocks. We deployed three eddy covariance towers along a burn severity gradient (i.e., severely burned, moderately burned, and unburned tundra) to mon...

The changes on abiotic features of ecosystems have rarely been taken into account by population dynamics models, which typically focus on trophic and competitive interactions between species. However, understanding the population dynamics of organisms that must modify their habitats in order to survive, the so-called ecosystem engineers, requires the explicit incorporation of abiotic interactio...

Spatial flows of materials and organisms across ecosystem boundaries are ubiquitous. Understanding the consequences of these flows should be a basic goal of ecosystem science, and yet it has received scant theoretical treatment to date. Here, using a simple, open, nutrient-limited ecosystem model with trophic interactions, we explore theoretically how spatial flows affect the functioning of loc...

abstract the effect of land use type on soil functioning within an ecosystem can be assessed and monitored using soil quality attributes. such studies, which are carried out to create a balance between the biological production and the maintenance and improvement of land resource quality, provide a framework for land degradation control and also for identification of sustainable management. in ...