Biao Zhang

The economic benefits of rainwater-runoff reduction by urban green spaces: a case study in Beijing, China.

Urbanization involves the replacement of vegetated surfaces with impervious built surfaces, and it often results in an increase in the rate and volume of rainwater surface runoff. Urban green spaces play a positive role in rainwater-runoff reduction. However, few studies have explored the benefits of rainwater-runoff reduction by urban green spaces. Based on inventory data of urban green spaces in Beijing, the paper evaluated the economic benefits of rainwater-runoff reduction by urban green spaces, using the rainwater-runoff-coefficient method as well as the economic valuation methods. The results showed that, 2494 cubic meters of potential runoff was reduced per hectare of green area and a total volume of 154 million cubic meters rainwater was stored in these urban green spaces, which almost corresponds to the annual water needs of the urban ecological landscape in Beijing. The total economic benefit was 1.34 billion RMB in 2009 (RMB: Chinese currency, US

Forest ecosystem services and their values in Beijing

1=RMB6.83), which is equivalent to three-quarters of the maintenance cost of Beijings green spaces; the value of rainwater-runoff reduction was 21.77 thousand RMB per hectare. In addition, the benefits in different districts and counties were ranked in the same order as urban green areas, and the average benefits per hectare of green space showed different trends, which may be related to the impervious surface index in different regions. This research will contribute to an understanding of the role that Beijings green spaces play in rainwater regulation and in the creation and scientific management of urban green spaces.

Estimation of biomass, net primary production and net ecosystem production of China's forests based on the 1999–2003 National Forest Inventory

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.

Regional differences of water conservation in Beijing’s forest ecosystem

Abstract The National Forest Inventory (NFI) is an important resource for estimating the national carbon (C) balance. Based on the volume, biomass, annual biomass increment and litterfall of different forest types and the 6th NFI in China, the hyperbolic relationships between them were established and net primary production (NPP) and net ecosystem production (NEP) were estimated accordingly. The results showed that the total biomass, NPP and NEP of Chinas forests were 5.06 Pg C, 0.68 Pg C year−1 and 0.21 Pg C year−1, respectively. The area-weighted mean biomass, NPP and NEP were 35.43 Mg C ha−1, 4.76 Mg C ha−1 year−1 and 1.47 Mg C ha−1 year−1 and varied from 13.36 to 79.89 Mg C ha−1, from 2.13 to 9.15 Mg C ha−1 year−1 and from −0.16 to 5.80 Mg C ha−1 year−1, respectively. The carbon sequestration was composed mainly of Betula and Populus forest, subtropical evergreen broadleaved forest and subtropical mixed evergreen–deciduous broadleaved forest, whereas Pinus massoniana forest and P. tabulaeformis forest were carbon sources. This study provides a method to calculate the biomass, NPP and NEP of forest ecosystems using the NFI, and may be useful for evaluating terrestrial carbon balance at regional and global levels.

Identifying important ecological areas for potential rainwater harvesting in the semi-arid area of Chifeng, China

The water conservation capacities of main forests in Beijing, China were estimated through the quantitative analysis. Various methods developed in published papers on forest hydrology were employed. The forests in Huairou, Yanqing, Miyun, Mentougou and Fangshan districts are the main contributors to water conservation (the cumulative ratio reaches 65%), and the forests in Tongzhou, Chaoyang, Shunyi and Daxing districts have the highest water conservation capacity (3000 m3/ha). Altitude and slope are the key factors to affect the water conservation capacity. The forests located in Plain Area, Hilly Area, Low Mountain, and Middle Mountain contributes 27%, 28%, 24% and 21% of the conserved water, respectively. The water conservation capacity of forests in Plain Area (2 948 m3/ha), is superior to the forests in other regions. And the forests situated on Flat Slope, Moderate Slope and Gentle Slope constitute the largest proportion (nearly 93%) of water conservation, while the forests on Flat Slope has the highest water conservation capacity (2 797 m3/ha), and the forest on Steep slope has the lowest water conservation capacity (948 m3/ha).

Ecosystem services research in China: Progress and perspective

Global water shortage is becoming increasingly severe, so the identification and protection of potential areas for harvesting water play important roles in alleviating drought. Suitable sites for potential water harvesting require a high runoff potential. Avoiding soil erosion caused by high surface runoff, however, is also necessary. We therefore developed a procedure for the continuous accounting of runoff potential based on the Soil Conservation Service curve number and potential risks of water and soil loss based on the universal soil loss equation to evaluate the potential for water harvesting. Suitable sites for rainwater harvesting covered 24.90% of the semi-arid area of Chifeng, southeastern Inner Mongolia, China. The best areas accounted for 8.4% of the study area. The southern part of the Greater Hinggnan Mountains in northern Chifeng had a large rainwater harvesting area, and the western and eastern parts of the Chifeng area belonging to Horqin Sandy Land and Hunshandake Sandy Land, respectively, had smaller rainwater-harvesting areas. The eight reservoirs in the Xilamulun River Basin were further analyzed as an example. Derived sites investigated by ground-truth field verification indicated a method accuracy of 87.5%. This methodology could be effective in other areas with similar requirements due to the increasing demand for water resources and requirements for the protection of soil-water resources.