[Biomass allocations and their response to environmental factors for grass species in an arid-hot valley].

The effects of water supply frequency, nutrient addition and clipping on biomass allocations among roots, stems and leaves as well as their allometric scaling relationships for six grass species from an arid-hot valley were investigated. The results showed that the fraction of leaf biomass significantly increased from 25.1% to 31.

[Element concentration in leaves and nutrient resorption efficiency on dry-red soil and vertisols in dry and hot valley in Yuanmou, China.].

By performing a pot experiment, the study compared leaf and litter element concentration between the dry-red soil and vertisols, and analyzed the interactive effects of soil types and species on leaf nutrient concentration and nutrient resorption efficiency. The results showed that the soil type significantly affected the concentrations of N, P, Ca, Mg, Cu, Zn, Fe and N:P in leaves as well as the concentrations of N, P, Mn and N:P in leaf litters. Concentrations of N, Mn and N:P in leaves and litters derived from the dry-red soil were significantly higher than those from the vertisols.

[Changes of plant leaf N, P, and K concentrations and species dominance in an arid-hot valley after ecosystem restoration].

Taking the arid-hot valley of Jinsha River, Southwest China as the object, a comparative study was made on the plant leaf N, P, and K concentrations and ratios as well as their relationships with species dominance in the restoration area and disturbed area, aimed to understand the effects of ecosystem restoration on the plant leaf stoichoimetric characteristics. Ecosystem restoration decreased the plant leaf N and P concentrations and P/K ratio significantly, but had lesser effects on the plant leaf K concentration. In restoration area, the plant leaf N, P, and K concentrations were averagely 10.