[Biomass and carbon storage of Phragmites australis and Spartina alterniflora in Jiuduan Shoal Wetland of Yangtze Estuary, East China].

By the methods of field survey and laboratory analysis, an investigation was conducted on the seasonal dynamics of biomass and carbon storage of Phragmites australis and Spartina alterniflora dominated vegetation belts in the Jiuduan Shoal Wetland of Yangtze Estuary, East China in 2010-2012. The organic carbon storage of the biomass (including aboveground part, underground part, and standing litter) of the two plants was the highest in autumn and the lowest in spring. The average carbon storage of the biomass of S. alterniflora per unit area (445.81 g x m(-2)) was much higher than that of P. australis (285.52 g x m(-2)), and the average carbon storage of the standing litter of S. alterniflora (315.28 g x m(-2)) was also higher than that of P. australia (203.15 g x m(-2)). However, the organic carbon storage in the surface soil (0-30 cm) under P. australis community (1048.62 g x m(-2)) was almost as twice times as that under S. alterniflora community (583.33 g x m(-2)). Overall, the carbon accumulation ability of P. australis community (3212.96 g x m(-2)) was stronger than that of the S. alterniflora community (2730.42 g x m(-2)). Therefore, it is of significance to protect the P. australis community in terms of carbon sequestration at the salt marsh.

[Ecological benefits of greening and related controlling factors in urban residential areas of Hangzhou: a quantitative analysis].

Based on the 1 m x 1 m high resolution aerial images in 2007 and the 30 m x 30 m Landsat 5 TM images in summer 2007, and with the help of GIS and remote sensing image interpretation, this paper calculated the normalized difference vegetation indices (NDVI) representing the overall ecological benefits of greening as well as the six controlling factors, i.e., multilayer structure height, area ratio of softness to hardness, greening rate, floor area ratio, greening area, and building density, in 30 typical urban residential quarters of west Hangzhou. The contributions of the controlling factors to the ecological benefits of greening as well as the quantitative relationships between the overall ecological benefits and the six controlling factors were analyzed by multiple linear regression and correspondence analysis, and some advises were given for the improvement of the ecological benefits. The contribution rate of the six factors was in the order of multilayer structure height > area ratio of softness to hardness > greening rate > floor area ratio > greening area > building density, and the contribution of multilayer structure height was far greater than that of the others whereas building density had the weakest effect on the ecological benefits. Correspondence analysis was effective in simplifying a complex data table into an intuitive two-dimensional chart, and thus, a potential powerful tool in decision-making for the improvement of ecological benefits of greening in urban residential quarters.

[Contribution rates of landscape driving factors in coastal reclamation zone based on CLUE-S model validation].

Based on the TM images, social-economic data, and field investigation data in 1990, 2000, and 2009, and by adopting redundancy analysis (RDA) and principal component analysis (PCA), this paper analyzed the contribution rates of landscape driving forces in coastal area of Fengxian reclamation zone at Yangtze Estuary. Kappa index was used to validate the simulation effectiveness of CLUE-S model. In the study area, anthropogenic landscape driving factors had a higher contribution rate than natural landscape driving factors (57.1% vs. 42.9%). The prediction accuracy rate of CLUE-S model was above 82%, the Kappa index of the main landscape types (farm land, unutilized land, and breeding ponds) was greater than 0.75, the simulation results were acceptable, and the landscape driving forces selected could better simulate the spatial distribution patterns of the abrupt transformation of the main landscape types.

[Spatiotemporal dynamics of land use and land cover changes in different reclamation zones of Yangtze Estuary].

Based on the TM and ETM remotely sensed images of Yangtze Estuary in 1987, 1995, 2000, and 2006, and by using RS, GIS, and mathematical statistical methods, this paper analyzed the dynamic changes of land use and land cover in different reclamation zones of the estuary. In terms of relative area occupied by each land use type, grassland showed significant spatial differences (P < 0.05) among the reclamation zones, while greenhouse land and paddy field showed significant temporal differences (P < 0.05). After eliminating the factor reclamation time, there was no significant difference in the land use diversity index among the reclamation zones. In terms of land use change rates, no significant spatial difference was observed among the reclamation zones, while greenhouse land and built-up area showed significant temporal differences. In terms of land use intensity and transformation direction, different reclamation zones had no significant differences. The land use dynamic changes in different reclamation zones of the estuary were mainly affected by reclamation time.

Effects of light on the growth and clonal reproduction of Ligularia virgaurea.

Ligularia virgaurea is a perennial herb that is widely distributed in the alpine meadow on the eastern Qinghai-Tibet plateau. We investigated the patterns of growth and reproduction of L. virgaurea under two contrasting levels of light conditions for two continuous growing seasons. Our results showed that the light effects on the maximum relative growth rate, the shoot weight ratio and the root weight ratio differed between the two growing seasons. L. virgaurea reproduced initially through rhizome in the second growing season, rather than sexual reproduction. The proportion of genets with clonal reproduction decreased under shaded conditions. A minimum genet size should be attained for clonal reproduction to begin under the shaded conditions. There was a positive linear relationship between clonal reproduction and genet size. Light level affected the allocation of total biomass to clonal structures, with less allocation under the full natural irradiance than under the shaded conditions. There seemed to be a trade-off between vegetative growth and clonal reproduction under the full natural irradiance, in terms of smaller relative growth rates of genets with clonal reproduction than those without clonal reproduction. L. virgaurea emphasized clonal reproduction under the full natural irradiance, while the plant emphasized vegetative growth under the shaded conditions.