[Stoichiometric characteristics of leaf carbon, nitrogen, and phosphorus of 102 dominant species in forest ecosystems along the North-South Transect of East China].

One hundred and twelve sampling sites in the forest ecosystems along the North-South Transect of Eastern China (NSTEC) were selected to study the stoichiometric characteristics and variability of leaf carbon (C), nitrogen (N), and phosphorous (P) of 102 dominant species. The contents of leaf C (Cmass), leaf N (Nmass), and leaf P (Pmass) ranged in 374.1-646.5 mg x g(-1), 8.4-30.5 mg x g(-1), and 0.6-6.2 mg x g(-1), with the arithmetic mean (AM) being 480.1, 18.3 and 2.0 mg x g(-1), and the variation coefficient (CV) being 11.1%, 27.5%, and 56.4%, respectively. The leaf C/N, C/P and N/P ranged from 14.1 to 64.1, from 70.9 to 838.6, and from 1.5 to 21.2, with the AM being 29.1, 313.9 and 11.5, and the CV being 32.8%, 48.3% and 44.1%, respectively. The mass ratio of C:N:P was 313.9:11.5:1, and the atom ratio was 810.9:25.4:1. As compared with those at global scale, the tree leaf Cmass and C/N in the study area were significantly higher, Nmass and N/P were significantly lower, while Pmass and C/P had less differences.

[Foliar water use efficiency and nitrogen use efficiency of dominant plant species in main forests along the North-South Transect of East China].

Based on the measurements of the foliar carbon content (Cmass, nitrogen content (Nmass), isotope abundance (delta13C and delta15N), and light response curve of 10 dominant plant species (Larix gmelinii, Quercus mongolica, Fraxinus mandshurica, Tilia amurensis, Acer mono, Pinus koraiensis, Cunninghamia lanceolata, Schima superba, Pinus massoniana, and Castanea henryi) in the main forests along the North-South Transect of Eastern China (NSTEC), this paper analyzed the differences and the relationships between the foliar water use efficiency and nitrogen use efficiency of the plant species. There existed significant differences in the foliar Nmass and delta15N among the plant species, manifesting as broadleaved species > coniferous species, and deciduous species > evergreen species. The maximum photosynthetic rate (Pn max) was coniferous species > broadleaved species, and deciduous species > evergreen species. Broadleaved and evergreen species tended to have higher foliar instantaneous water use efficiency (WUEi) and long-term water use efficiency (WUE), as compared to coniferous and deciduous species, but an opposite trend was observed in the foliar instantaneous nitrogen use efficiency (NUE) and long-term nitrogen use efficiency (NUE). Moreover, there was a significant difference in the foliar NUE between evergreen and deciduous species. No significant correlation was observed between WUEi and WUE, but a significant positive correlation existed between NUEi and NUE. There was a significant negative correlation between the foliar water use efficiency and nitrogen use efficiency at instantaneous or long-term time scales. In sum, the foliar water use efficiency and nitrogen use efficiency were dominated by plant life-form, and a trade-off existed between the two resources use efficiencies.

Spatial variations of Pb in the vertical zone of the soil-plant system in the Changbai Mountain National Nature Reserve.

The characteristics of vertical and horizontal variations of lead element(Pb) in soil-plant system of vertical zone in Changbai Mountain National Nature Reserve(CNNR) were studied. The results showed that Pb concentrations in soils of vertical zone are all above 25 mg/kg, and the average Pb concentration of each soil zone negatively correlates its degree of variation, i.e. brown coniferous forest soil zone has the lowest average Pb concentration of four soil zones, and the highest horizontal variation; however, mountain soddy forest soil has the highest average Pb concentration, and the lowest horizontal variation; the average concentration of plant Pb of each plant zone is lower than the worldwide average level of Pb in plant(Clarke), respectively, and plant Pb content order is consistent with soil Pb content order, but their horizontal variations are different from those in soil zones, the variation of mountain tundra forest zone is highest, but Betula ermanii forest zone the lowest. Vertical variation of plant Pb is obviously higher than that in soils with variation coefficient of 89.76%; the enrichment capability of plant for Pb is depended on the plant types and the different organs of plant; parent material and parent rock, pH values, soil organic matter and soil particle fraction etc. are the main factors influencing variations of Pb content in soil-plant system of vertical zone in CNNR.