Wang Xiaoke

Primary evaluation of carbon sequestration potential of wetlands in China

Abstract As one of the important ecosystem services of wetlands, carbon sequestration potential of lakes and swamps in China were investigated. Significant differences were found among the carbon sequestration potential of various lakes, determined by natural conditions and human disturbance. In this study, swamps had a carbon sequestration potential of 4.90 TgC, much higher than lakes in China. Mangrove and coastal marsh have the highest carbon sediment rate among swamps. Carbon sequestration potential in returning farms to lakes and swamps was 30.26 and 0.22 GgC. … a−1, respectively. Under the ongoing national wetland conservation action plan in China, the carbon sequestration potential of wetland restoration was 6.57 GgC. … a−1. Protection and restoration measurements can improve carbon sequestration potential of wetlands.

Carbon budgets of three temperate forest ecosystems in Dongling Mt., Beijing, China

There is a general agreement that forest ecosystems in the Northern Hemisphere function as significant sinks for atmospheric CO2; however, their magnitude and distribution remain large uncertainties. In this paper, we report the carbon (C) stock and its change of vegetation, forest floor detritus, and mineral soil, annual net biomass increment and litterfall production, and respiration of vegetation and soils between 1992 to 1994, for three temperate forest ecosystems, birch (Betula platyphylla) forest, oak (Quercus liaotungensis) forest and pine (Pinus tabulaeformis) plantation in Mt. Dongling, Beijing, China. We then evaluate the C budgets of these forest ecosystems. Our results indicated that total C density (organic C per hectare) of these forests ranged from 250 to 300 t C ha−1, of which 35–54 t C ha−1 from vegetation biomass C and 209–244 t C ha−1 from soil organic C (1 m depth, including forest floor detritus). Biomass C of all three forests showed a net increase, with 1.33–3.55 t C ha−1 a−1 during the study period. Litterfall production, vegetation autotrophic respiration, and soil heterotrophic respiration were estimated at 1.63–2.34, 2.19–6.93, and 1.81–3.49 t C ha−1 a−1, respectively. Ecosystem gross primary production fluctuated between 5.39 and 12.82 t C ha−1 a−1, about half of which (46%–59%, 3.20–5.89 t C ha−1 a−1) was converted to net primary production. Our results suggested that pine forest fixed C of 4.08 t ha−1 a−1, whereas secondary forests (birch and oak forest) were nearly in balance in CO2 exchange between the atmosphere and ecosystems.

Allergenic pollen plants and their influential factors in urban areas

Abstract Owing to unsuitable green space construction, abundant allergenic pollen plants are centralized in urban areas, producing allergenic pollen. A mass of airborne allergenic pollen could cause pollinosis to badly influence peoples robustness. To provide scientific basis for reasonable green space construction, the research advances of allergenic plants were reviewed. Firstly, species composition, phenological characteristics and influential factors (which include unsuitable green land construction, urban heat island effect, traffic pollution, etc.) were summarized. Secondly, the strategies controlling allergenic pollen plants were proposed. Thirdly, some problems on allergenic plants worthy of more research, including allergenic mechanism and methodology, were also put forward.

Modeling the interannual variation and response to climate change scenarios in gross and net primary productivity of Pinus elliottii forest in subtropical China

Abstracts In this study, the BIOME-BGC model, a biogeochemical model, was used and validated to estimate GPP (Gross Primary Productivity) and NPP (Net Primary Productivity) of Pinus elliottii forest in red soil hilly region and their responses to inter-annual climate variability during the period of 1993–2004 and climate change scenarios in the future. Results showed that the average total GPP and NPP were 1941 g C m −2 a −1 and 695 g C m −2 a −1 , and GPP and NPP showed an increasing trend during the study period. The precipitation was the key factor controlling the GPP and NPP variation. Scenario analysis showed that doubled CO 2 concentration would not benefit for GPP and NPP with less than 1.5% decrease. When CO 2 concentration fixed, GPP responded positively to precipitation change only, and temperature increase by 1.5°C with precipitation increase, while NPP responded positively to precipitation change only. When CO 2 concentration was doubled and climate was changed, GPP and NPP responded positively to precipitation change, and GPP also responded positively to temperature increase by 1.5°C with precipitation change.

Multichannel automated chamber system for continuous monitoring of CO2 exchange between the agro-ecosystem or soil and the atmosphere

Abstract A multichannel automated chamber system was developed for continuous monitoring of CO2 exchange at multiple points between agro-ecosystem or soil and atmosphere. This system consisted of an automated chamber subsystem with a CO2 concentration analyzer and a data logging subsystem. Both subsystems were under the control of a programmable logic controller (PLC). The automated chamber subsystem contained 18 chambers (50 cm × 50 cm × 50 cm) and a compressor. The chamber lids were closed and can be automatically opened. During measurement, one of the 18 chambers was kept closed for three minutes for measuring and the other chambers were kept open to maintain the natural soil conditions to the maximum extent. Environmental variables were simultaneously measured using sensors and recorded by the data logger. The reliability of the multichannel automated chamber system was tested and the results showed that the turbulence of the fans had no significant effect on the CO2 exchange. The changes in the air and the temperature of soil and soil moisture inside the chambers, caused by the enclosure of the chambers, were not significant. The net ecosystem CO2 exchange for the wheat ecosystem was −2.35 μmol·m−2·s−1 and the soil respiration was 3.87 μmol·m−2·s−1 in the wheat field, and 6.61 μmol·m−2·s−1 in the apple orchard.

Estimation of soil carbon saturation and carbon sequestration potential of an agro-ecosystem in China

Soil is believed to be the most important sink for sequestering atmospheric carbon. Hence, estimating soil carbon sequestration potential has been carried out for different regions and agricultural practices. However, soil carbon saturation (SCS), a fundamental concept for estimating soil carbon sequestration potential, has not been estimated for countries or regions. In this study, we estimated SCS of agricultural land for most provinces in China for 1990 by the DNDC model, a carbon and nitrogen biogeochemical cycle model, in order to provide a basis for farmers to select the land use, tillage and fertilization regimes to sequester more carbon. The result showed that SCS was as low as 0.48% in Tianjin and up to 5.14% in Tibet. There was a positive correlation between SCS and the proportion of paddy field in a province. In 1990, cropland soil carbon sequestration potential (SCSP) in China was -0.969 Gt C (-2.706 to 0.767 Gt C). This suggests that agricultural soil will be a carbon source to the atmosphere if agricultural practices are not altered. However, SCSP differed between provinces in China. SCSP was highest in Tibet (7.9 t C ha-1) and lowest in Heilongjiang Province (-60.8 t C ha-1), with a gradual decrease from south to north in China.

Evolution of Sustainable Carbon Cycling Processes in China

Abstract This report summarizes the surveys on carbon inventories and initiatives on sustainable carbon cycling taken by RCEES. The first part of this report deals with the concept of sustainable carbon cycling, the historical evolution of carbon cycling processes in China, carbon pool enhancement, value addition, carbon sequestration and carbon balance. The second part covers the modeling of carbon dynamics, emission inventories of various carbon-containing greenhouse gases and their potential abatement measures.