The (asymptotic) degree distributions of the best known “scale free” network models are all similar and are independent of the seed graph used. Hence it has been tempting to assume that networks generated by these models are similar in general. In this paper we observe that several key topological features of such networks depend heavily on the specific model and the seed graph used. Furthermor...

this study was carried out to investigate the effect of crown canopy of ziziphus spina-christi on seed bank characteristics (density and similarity with above ground flora) in two sites with saline-alkaline and alkaline soils. in each soil, forty plots were established, half in and half outside of z. spina-christi cover. in each plot, soil sampling was done from 0-5 and 5-10 cm depths. paired a...

research on crop response to deficit irrigation is important to reduce agriculture water use in areas where water is limited resource. using drought resistant landraces with irrigation scheduling based on phenological stages in semi-arid and arid regions may provide an opportunity to optimize irrigation efficiency and water savings in these regions. in order to evaluate of yield and yield compo...

.............................................................................................................................................................................. 1 Background and Purpose ................................................................................................................................................. 2 Objectives and hypotheses ..........................

the study of soil seed bank provides useful information on management and restoration of natural ecosystems. in the arid environments, some perennial plants may cause accumulation of seed bank under their canopy, thereby protecting them against the livestock herbivory and the other environmental factors. this study was conducted with objective to investigate effect of perennial plants on densit...

in order to study the effects of different amounts of nitrogen and plant density on yield, yield components and seed oil percentage of pumpkin (cucurbita pepo l.) an experiment was conducted as split plot based on randomized complete block design with two factors and three replications at agricultural research field station of ferdowsi university of mashhad, iran, during growing season 2010-201...

Seed dispersal and germination are critical to the fitness of all tree species. Moreover, among most trees the percentage of seeds that become seedlings, or “seedling success”, is very low. We examined seed success of a dominant lowland rainforest species, Pentaclethra macroloba, across a soil moisture gradient. Previous studies have established that P. macroloba has reduced seed germination ra...

Insects introduced as biological control agents of diffuse knapweed, Centaurea diffusa, primarily reduce seed production. Knapweed densities appear to be resilient to greatly reduced seed production. We have used measurements of seedling density and survival, and production of seeds by flowering diffuse knapweed plants to develop functions for a model of knapweed populations. These simulations ...