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Leaf nitrogen resorption is very important to Phyllostachys edulis development because the withdrawn nitrogen can help newly emerging and growing culms. However, few studies have focused on the ontogenetic changes in leaf nitrogen resorption of P. edulis. Here, we examined the variability in mature leaf nitrogen concentrations (Nm), nitrogen resorption efficiency (NRE) and proficiency (NRP or Ns) and leaf-level nitrogen use efficiency (NUE) of the current-, 3rd- and 5th-year culms in P. edulis stands under extensive management. Analyses of variance and correlation indicated that patterns of Nm, NRP, NRE and NUE were markedly affected by culm age and leaf nitrogen status. Nm, Ns and NRE were significant higher in younger (current-year) culms with 1-year lifespan leaves, while NUE was markedly higher in older (3rd- or 5th-year) culms with 2-year lifespan leaves. Significant linear correlations between Nm and NRP, NRE and NUE, Nm and NUE, Ns and NRE were found for each culm age, and Nm was significantly positively correlated to NRE for all culms pooled. Higher proficiency in older culms led to higher NUE and lower NRE, these relationships can be modulated by Nm, which in turn, is restrained by leaf N availability and acquisition. Our results revealed that at the intraspecific level, P. edulis can adjust its leaf NRE, NRP, and leaf-level NUE in concert with culm development. Understanding nitrogen resorption characteristics and NUE of P. edulis can help decision-makers design appropriate deforestation strategies and achieve precise N fertilization for sustainable bamboo forest management. [ABSTRACT FROM AUTHOR]

Water supply services (WSSs) are critical for the regional water balance and water circulation, but relevant studies have not established the relationship between WSSs and human well-being. This research identifies the scope of areas that benefit from WSSs from an ecosystem service flow perspective. Moreover, the path and quantity of the flow of WSSs are simulated to provide a scientific theoretical basis for ecosystem service management and ecological compensation. The Dongjiang Lake Basin is a national priority river basin in China where ecological compensation pilot programmes concerning water resources are top priorities. Dongjiang Lake Basin experienced an increase and then a decrease in the overall supply of water, with an average net water supply of 1096-1500 mm for the years 1995, 2000, 2005 and 2010. The water demand increased each year in service beneficiary areas (SBAs), varying from 387 to 580 mm. Overall, Dongjiang Lake Basin met the net water demands of the actual SBAs in the lower reaches, but a gap in the water supply and demand emerged gradually. This research provides an understanding of the functional mechanisms for the provision, demand and flow of WSSs and provides a scientific theoretical basis for ecosystem service management and ecological compensation. [ABSTRACT FROM AUTHOR]

Based on forest inventory data (FID) at sublot level, we estimated the carbon sequestration in forest vegetation of Beijing, China in 2009. In this study, the carbon sequestration in forest vegetation at sublot level was calculated based on net biomass production ( ΔB) which was estimated with biomass of each sublot and function relationships between ΔB and biomass. The biomass of forested land was calculated with biomass expansion factors (BEFs) method, while those of shrub land and other forest land types were estimated with biomass, coverage and height of referred shrubs and shrub coverage and height of each sublot. As one of special forested land types, the biomass of economic tree land was calculated with biomass per tree and tree number. The variation of carbon sequestration in forest vegetation with altitude, species and stand age was also investigated in this study. The results indicate that the carbon sequestration in forest vegetation in Beijing is 4.12 × 10 tC/yr, with the average rate of 3.94 tC/(ha·yr). About 56.91% of the total carbon sequestration in forest vegetation is supported by the forest in the plain with an altitude of < 60 m and the low mountainous areas with an altitude from 400 m to 800 m. The carbon sequestration rate in forest vegetation is the highest in the plain area with an altitude of < 60 m and decreased significantly in the transitional area from the low plain to the low mountainous area with an altitude ranging from 200 m to 400 m due to intensive human disturbance. The carbon sequestration of Populus spp. forest and Quercus spp. forest are relatively higher than those of other plant species, accounting for 25.33% of the total. The carbon sequestration in vegetation by the forest of < 40 years amounts to 45.38% of the total. The carbon sequestration rate in forest vegetation peaks at the stand age of 30-40 years. Therefore, it would be crucial for enhancing the capability of carbon sequestration in forest vegetation to protect the forest in Beijing, to limit human disturbance in the transitional area from the plain to the low mountain area, and to foster the newly established open forest. [ABSTRACT FROM AUTHOR]

As the most important ecosystem in Beijing, the forest supports a lot of ecosystem services to local and around communities, which plays a key role in the maintenance of urban ecological security. However, the valuation on the forest ecosystem services based on regional scale could not provide precise and reasonable values for forestry sector management. In this study, we estimated the magnitudes and economic values of the forest ecosystem services in Beijing at sublot level. The economic value of forest ecosystem services in Beijing was estimated to be 19 339.71×106 yuan (RMB) in 2004. Among all the ecosystem services indicators we estimated in this study, only fruit, timber and part of the recreation (which only include the tourism income from the forest parks and scenic areas, but not include that from other forest types) were measured in the social economic system. As estimated in this study, more than 82.19% of the economic value of forest ecosystem services could not be measured in the socio-economic statistical system. The importance of forest ecosystem services in Beijing to human welfare was underestimated by the socio-economic system. Therefore, the policies about the eco-compensation of forest ecosystem services should be established to maintain the sustainable supply of the forest ecosystem services in Beijing. [ABSTRACT FROM AUTHOR]

The land use patterns in Guyuan City, Ningxia Hui Autonomous Region of China, have changed greatly over the years, due to population growth and farming and stock raising development. This study, using 50-year statistical data of cultivated land and 14-year spatial data of land use pattern, analyzed the developmental stages, the character, and the spatial variance of farmland in the city, and discussed the driving forces of cultivated land changes based on empirical and conceptual statistical models. First, the change of cultivated land area went through different stages of rapid increase, fluctuating change, decrease and rapid decrease from 1949 to 2004, additionally, social and economic policies in different stages had an important impact on farmland variance. Second, from 1986 to 2000, the quantity of cultivated land increased, but its quality decreased. Third, social and economic factors are determinant factors in cultivated land transition. Five constructed paths explain cultivated land transition. Factors that have direct or indirect effects on farmland include the economy ( X eco), the population ( X pop), agricultural output ( X agr), and scientific input ( X sci). The sequence of impact was X eco> X pop> X sci> X agr. Among all these impacts, X eco was the major positive one, and X pop was the major negative one. It is urgent to take measures or adopt a policy to stop the vicious cycle in eco-environment and agriculture production. Otherwise, negative patterns of farmland use will increase, and high-quality cultivated land will continue to decline. [ABSTRACT FROM AUTHOR]

The shrinking and drying up of wetlands in arid and semiarid areas of China have been widely observed in the recent years, but there has been no consensus on whether the aggravation is caused by human activities or by global climate warming. For a better understanding of the cause, this study investigates the dynamic changes of Baiyangdian Lake wetland over the last 40 years. It is shown that since the 1980s, Baiyangdian Lake has suffered from an insufficient water input and shrunk considerably. By using SPSS11.0, this study undertakes a detailed analysis on the significance of the effects of the possible driving factors for the degradation. It is identified that the North China Plain has been warming up significantly in recent years, which causes a significant reduction in the precipitation and inflow to the lake. Although human disturbances such as the irrigation and storage of water in reservoirs do not play a decisive role, they accelerate the degradation and their effects should be minimized. [ABSTRACT FROM AUTHOR]