[Hydro-chemical Characteristics and Quality Assessment of Surface Water in Gongga Mountain Region].

The concentrations of major ions (K+, Na+, Ca2+, Mg2+, CO32-, HCO3-, Cl-, and SO42-), heavy metals (Cu, Cd, Pb, and Zn), and nutrient elements (N and P) in surface water collected from Gongga Mountain region were analyzed to decipher their spatial distribution and assess the water quality. The descriptive statistics, Gibbs Figure, and triangular diagrams of anions and cations were employed, and single factor evaluation was conducted. The results showed that the average value of total dissolved solid (TDS) in Gongga Mountain region was 103.22 mg·L-1 indicating low salinity, and the hydro-chemical type was HCO3-Ca. For whole catchment, the major ion chemistry of river water was controlled by carbonate weathering, while the effect of atmospheric deposition was high in the eastern area. The overall concentrations of heavy metals and nutrient elements were low, and the eastern area had significantly higher concentrations than the west. The quality of surface water was good from the whole point of view, while that in the west was better than the east. It indicated that the spatial distribution was mainly controlled by natural factors, but the water of southeast slope had been affected by humans.

Bryophyte species richness and composition along an altitudinal gradient in Gongga Mountain, China.

An investigation of terrestrial bryophyte species diversity and community structure along an altitudinal gradient from 2,001 to 4,221 m a.s.l. in Gongga Mountain in Sichuan, China was carried out in June 2010. Factors which might affect bryophyte species composition and diversity, including climate, elevation, slope, depth of litter, vegetation type, soil pH and soil Eh, were examined to understand the altitudinal feature of bryophyte distribution. A total of 14 representative elevations were chosen along an altitudinal gradient, with study sites at each elevation chosen according to habitat type (forests, grasslands) and accessibility. At each elevation, three 100 m × 2 m transects that are 50 m apart were set along the contour line, and three 50 cm × 50 cm quadrats were set along each transect at an interval of 30 m. Species diversity, cover, biomass, and thickness of terrestrial bryophytes were examined. A total of 165 species, including 42 liverworts and 123 mosses, are recorded in Gongga mountain. Ground bryophyte species richness does not show any clear elevation trend. The terrestrial bryophyte cover increases with elevation. The terrestrial bryophyte biomass and thickness display a clear humped relationship with the elevation, with the maximum around 3,758 m. At this altitude, biomass is 700.3 g m(-2) and the maximum thickness is 8 cm. Bryophyte distribution is primarily associated with the depth of litter, the air temperature and the precipitation. Further studies are necessary to include other epiphytes types and vascular vegetation in a larger altitudinal range.

Comparison of element concentrations in fir and rhododendron leaves and twigs along an altitudinal gradient.

Concentrations of 23 elements (Ca, K, Mg, P, Al, Cu, Fe, Mn, Mo, Na, Ni, Zn, Ag, Ba, Be, Cd, Co, Cr, Pb, Sb, Th, Tl, and V) in leaf and twig samples of a fir (Abies fabri) and a rhododendron (Rhododendron williamsianum) collected along an altitudinal gradient on Mount Gongga, China, are reported in the present study. Most of the macronutrients (K and P), micronutrients (Fe, Zn, Cu, Na, Ni, Mo, and Al), and trace elements (Pb, Tl, Ag, Cd, Ba, Co, V, Be, and Cr) are significantly enriched in fir when compared to rhododendron; however, Ca, Mg, Mn, Ba, and Cd are more enriched in rhododendron than in fir. Most of the elements in both plants are more significantly enriched in twigs than in leaves. The relationship between element concentration in plants and altitudinal gradient is nonlinear. Altitudes of 3,200 and 3,400 m are turning points for fir and rhododendron growth, respectively. Concentrations of all trace elements in the two plants along the altitudinal gradient are well below the toxic level in plants. No known industrial sources of the elements investigated exist in the Mount Gongga area, China. Element concentrations in the present study are higher than those found in mosses collected from the same area, indicating that the area is not contaminated. The element concentrations that we observed in plant samples were due to soil uptake. The pronounced differences between the two species are due to the different uptake characteristics of fir and rhododendron.