Tests of transition height and gradient modifications are presented, based on experimental evidences and model efforts.
McIntyre and Hobbs [Conservation Biology 13 (1999) 1282] recently proposed a model in which landscapes can be classified according to the amount of habitat remaining and in which the remaining habitat can correspond to a continuum or gradient of modification.
Concomitant with the reduction of the pH gradient after modification was a decrease in the phosphorylation state of the adenine nucleotides measured either as ATP/Pi by MRS or [ATP]/[ADP][P i)] in tumour extracts.
To test the nanoforce gradient hypothesis, modifications were made to the design of Sharklet AF, resulting in a range of nanoforce gradients43.
A numerical convergence study is used to show that for a first order convergence of our discrete gradients grid modification is sufficient, whereas to achieve second order convergence grid optimization is mandatory.
The optimization methods are (i) the black-box method with finite difference gradients, (ii) a modification where gradients are found by an algorithm based on the implicit function theorem, and (iii) an all-atonce method where the flow and design variables are simultaneously altered.
On a grid of 1386 lat/long cells (landscape units, c. 30 km2) we used simple information on land cover and easily measurable landscape metrics to identify a gradient of landscape modification for the model region of Lower Saxony, Germany.
We linked the gradient of landscape modification intensity to richness patterns of eight groups of vascular plants that were aggregated using residence and threat status and habitat preferences of the species.
We compiled geographic range data for 180 bird, 119 butterfly, 204 tree and 219 understorey plant species sampled along a gradient of habitat modification ranging from near-primary forest through young secondary forest and agroforestry systems to annual crops in the southwestern lowlands of Cameroon.
We saw no consistent gradients in effect modification by individual characteristics and social economic status, and in particular no gradient by either individual level socioeconomic status or area-based socioeconomic status, which was based on small areas (block groups) that were designed to minimize within area gradients while maximizing between area gradients.
