No abstract

Soil organic carbon (SOC) stock in mountain ecosystems is highly heterogeneous because of differences in soil, climate, and vegetation with elevation. Little is known about the spatial distribution and chemical composition of SOC along altitude gradients in subtropical mountain regions, and the controlling factors remain unclear. In this study, we investigated the changes in SOC stock and chemical composition along an elevation gradient (219, 405, 780, and 1268 m a.s.l.) on Lushan Mountain, subtropical China. The results suggested that SOC stocks were significantly higher at high altitude sites (1268 m) than at low altitude ones (219, 405, and 780 m), but the lower altitude sites did not differ significantly. SOC stocks correlated positively with mean annual precipitation but negatively with mean annual temperature and litter C/N ratio. The variations in SOC stocks were related mainly to decreasing temperature and increasing precipitation with altitude, which resulted in decreased litter decomposition at high altitude sites. This effect was also demonstrated by the chemical composition of SOC, which showed lower alkyl C and higher O‐alkyl C contents at high altitude sites. These results will improve the understanding of soil C dynamics and enhance predictions of the responses of mountain ecosystem to global warming under climate change.

No abstract

Plant stoichiometry in relation to environmental factors has recently received increasing attention. However, regulations and variations of plant elements in different environments are not well understood. We investigated homeostasis and variation of macroelements (C, N, P, K, Ca, Mg, and S), essential microelements (Fe, Mn, and Zn) and non-essential elements (Al) in Quercus variabilis leaves at a range of natural P concentration from P-rich to P-deficient (typical subtropical conditions) soils. The results showed that element ratios were more stable (except for C:P and Mn:P) than individual element concentrations. Of the individual elements, protein-related elements (e.g. N, S, and Fe) were correlated with leaf P while non-protein elements (e.g. C, K, and Ca) were not. The degree of homeostasis indicated that macroelements (N, P, and Ca) concentrations were more variable than microelements (Mn, Zn, and Al) under a varying element concentration in soils. These results suggest that local P-rich geochemistry alters leaf element concentrations, but not element ratios, and that plants are capable of meeting their needs for elements in certain proportions to achieve optimal performance under varying elemental conditions.