this study was conducted to choose the best species for plantation on a poor drainage soil in southern coast of caspian sea, iran. nutrient concentrations in live and senescent leaves and soil properties were compared among alnus subcordata c.a.mey (n-fixing tree), populus deltoides­ marsh. (non n-fixing tree)and taxodium distichum (l.) rich. (coniferous tree) plantations. in each of these plan...

The presence of prey heterogeneity and weakly interacting prey species is frequently viewed as a stabilizer of predator-prey dynamics, countering the destabilizing effects of enrichment and reducing the amplitude of population cycles. However, prior model explorations have largely focused on long-term, dynamic attractors rather than transient dynamics. Recent theoretical work shows that the pre...

there are human and animal health concerns related to drainage systems because nutrients, especially nitrogen and phosphorus, can contaminate water supplies. a field study was conducted on consolidated paddy fields of sari agricultural sciences and natural resources university, northern iran (36.3°n, 53.04°e), to determine the effect of subsurface drain depth and spacing on nitrogen (n) and pho...

Wood contains the majority of the nutrients in tropical trees, yet controls over wood nutrient concentrations and their function are poorly understood. We measured wood nutrient concentrations in 106 tree species in 10 forest plots spanning a regional fertility gradient in Panama. For a subset of species, we quantified foliar nutrients and wood density to test whether wood nutrients scale with ...