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Pan X.,Chinese Academy of Forestry | Pan X.,Beijing Key Laboratory of Wetland Services and Restoration | Pan X.,Beijing Hanshiqiao National Wetland Ecosystem Research Station | Ping Y.,Chinese Academy of Forestry | And 16 more authors.
PLoS ONE | Year: 2017

Plant litter is an indispensable component of constructed wetlands, but how the submergence of plant litter affects their ecosystem functions and services, such as water purification, is still unclear. Moreover, it is also unclear whether the effects of plant litter submergence depend on other factors such as the duration of litter submergence, water source or litter species identity. Here we conducted a greenhouse experiment by submerging the litter of 7 wetland plant species into three types of water substrates and monitoring changes in water nutrient concentrations. Litter submergence affected water quality positively via decreasing the concentration of nitrate nitrogen and negatively via increasing the concentrations of total nitrogen, ammonium nitrogen and total phosphorus. The effects of litter submergence depended on the duration of litter submergence, the water source, the litter species identity, and the plant life form. Different plant species had different effects on the water nutrient concentrations during litter submergence, and the effects of floating plants might be more negative than that of emergent plants. These results are novel evidence of how the submergence of different plant (life form) litter may affect the purification function of constructed wetlands. For water at low eutrophication levels, submerging a relative small amount of plant litter might improve water quality, via benefiting the denitrification process in water. These findings emphasized the management of floating plant litter (a potential removal) during the maintenance of human-controlled wetland ecosystems and provided a potential tool to improve the water quality of constructed wetlands via submerging plant litter of different types. © 2017 Pan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Yang Y.,Basin Water | Yang Y.,China Institute of Water Resources and Hydropower Research | Qiu J.,Sun Yat Sen University | Su H.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | And 9 more authors.
Remote Sensing | Year: 2017

The partitioning of available energy between sensible heat and latent heat is important for precise water resources planning and management in the context of global climate change. Land surface temperature (LST) is a key variable in energy balance process and remotely sensed LST is widely used for estimating surface heat fluxes at regional scale. However, the inequality between LST and aerodynamic surface temperature (Taero) poses a great challenge for regional heat fluxes estimation in one-source energy balance models. To address this issue, we proposed a One-Source Model for Land (OSML) to estimate regional surface heat fluxes without requirements for empirical extra resistance, roughness parameterization and wind velocity. The proposed OSML employs both conceptual VFC/LST trapezoid model and the electrical analog formula of sensible heat flux (H) to analytically estimate the radiometric-convective resistance (rae) via a quartic equation. To evaluate the performance of OSML, the model was applied to the Soil Moisture-Atmosphere Coupling Experiment (SMACEX) in United States and the Multi-Scale Observation Experiment on Evapotranspiration (MUSOEXE) in China, using remotely sensed retrievals as auxiliary data sets at regional scale. Validated against tower-based surface fluxes observations, the root mean square deviation (RMSD) of H and latent heat flux (LE) from OSML are 34.5 W/m2 and 46.5 W/m2 at SMACEX site and 50.1 W/m2 and 67.0 W/m2 at MUSOEXE site. The performance of OSML is very comparable to other published studies. In addition, the proposed OSML model demonstrates similar skills of predicting surface heat fluxes in comparison to SEBS (Surface Energy Balance System). Since OSML does not require specification of aerodynamic surface characteristics, roughness parameterization and meteorological conditions with high spatial variation such as wind speed, this proposed method shows high potential for routinely acquisition of latent heat flux estimation over heterogeneous areas. © 2017 by the authors; licensee MDPI, Basel, Switzerland.


Wen W.,Chinese Academy of Forestry | Wen W.,Beijing Normal University | Wen W.,Beijing Key Laboratory of Wetland Services and Restoration | Li X.,Beijing Normal University | And 5 more authors.
Geosciences Journal | Year: 2016

Net nitrogen mineralization is one of the nitrogen cycling process, and it is very important to understand nitrogen mineralization characteristics in degradation grassland. In the upper 0–10 cm soil layer of Stipa grandis P. A. Smirn. grassland in the Xilin river basin, Inner Mongolia, we studied the soil net nitrogen mineralization and nitrification among three varying stages of degradation grassland and analyzed the relationship between the mineralization rate of the soil net nitrogen and environmental factors, using the resin-core incubation method. Our results demonstrated that, from May to October 2012, the accumulated net nitrogen mineralization was 21.620 mg kg−1, 12.486 mg kg−1, and 48.053 mg kg−1 in the slightly, medium, and heavily degraded grasslands, respectively and varied greatly among the three stages of degradation shown by the S. grandis grassland plots. During the cultivation period, the variation of net nitrogen mineralization and nitrification was similar to the variation of soil mineral nitrogen. The higher soil mineral nitrogen content indicated higher mineralization of net nitrogen. In July and August, soil moisture was positively correlated with the net nitrogen mineralization rate, and the correlation coefficients between these two factors of 0.73, 0.58, and 0.79 for the slightly, medium, and heavily degraded plots, respectively. The rates of net nitrogen mineralization and nitrification were negatively correlated with soil total nitrogen, but positively correlated with C/N ratio, and weakly correlated with other physicochemical properties. © 2016 The Association of Korean Geoscience Societies and Springer-Verlag Berlin Heidelberg


Yan L.,CAS Institute of Botany | Yan L.,Chinese Academy of Forestry | Yan L.,Beijing Key Laboratory of Wetland Services and Restoration | Zhou G.S.,CAS Institute of Botany | And 4 more authors.
Journal of Cleaner Production | Year: 2015

Grasslands in Tibetan Plateau play an important role in carbon emission reduction. Accurately evaluating the carbon budget of alpine grassland ecosystems is of great importance. Based on the parameterization and validation of a process-based ecosystem model (Terrestrial Ecosystem Model, TEM5.0), we analyze temporal and spatial dynamics and patterns of grassland ecosystem carbon emission and sequestration of Tibetan Plateau in China from 1961 to 2010. Alpine grasslands act as a carbon sink with mean annual value of 10.12TgCyr-1 during the past 50 years. The alpine meadow contributes most to the sink at 9.04TgCyr-1, while the alpine steppe only contributes 2.03TgCyr-1. 83.7% of the total area trends to be carbon sink and only 0.2% of the region showed no significant trend. Furthermore, the annual net ecosystem productivity shows significantly positive relationship with increasing temperature and atmosphere CO2 concentration, but it shows no significant relationship with precipitation. Alpine grasslands in Qinghai-Tibetan Plateau is a carbon sink and sequestrate totally 520TgC from 1961 to 2010. The carbon budget of alpine experienced dramatically spatial and temporal dynamics during past 50 years. Inter-annual variability of the net ecosystem productivity mainly depends on different sensitivities of net primary productivity and heterotrophic respiration to temperature and precipitation variability. Temperature and atmosphere CO2 concentration are main driving forces of carbon budget dynamics of grassland ecosystems in Qinghai-Tibetan Plateau during 1961-2010. © 2015 Elsevier Ltd.


Cui L.,Chinese Academy of Forestry | Cui L.,Beijing Key Laboratory of Wetland Services and Restoration | Li W.,Chinese Academy of Forestry | Li W.,Beijing Key Laboratory of Wetland Services and Restoration | And 14 more authors.
Ecological Engineering | Year: 2016

Understanding the basic characteristics of wetland seed banks and the distribution of those seeds is fundamental to providing a theoretical basis for vegetation restoration and wetland management. This study explored the relationship between standing vegetation and the soil seed bank representing four vegetation cover types on the shoreline of Lake Taihu (China) using a seed germination method. The vegetation cover types consisted of the fleabane lakeshore zone (Zone A), bush and grass lakeshore zone (Zone B), crop lakeshore zone (Zone C), and natural reed lakeshore zone (Zone D). The viability of the seeds of all species found during a survey of standing vegetation in the summer of 2010 was assessed using greenhouse germination trials. The fleabane, bush and grass, crop, and natural reed lakeshore zones had 4, 16, 8, and 6 species from the seed bank, respectively. Sorensen similarity coefficients resulting from comparisons of the species found in the seed bank and in the standing vegetation of those same four habitats were 0.250, 0.333, 0.143, and 0.154, respectively. Low similarity levels between standing vegetation and the seed banks indicate that we should increase work on wetland protection and management because of its potentially low recovery ability. Seed density was significantly lower in Zone B (4933±1683 number/m2) than in the other zones (Zone A: 1160±502 number/m2; Zone C: 1360±587 number/m2; and Zone D: 1200±961 number/m2. The vertical distribution of seeds in the seed bank at the four zones showed a significant decreasing trend with increasing soil depth. The reserves of seeds in the topsoil seed bank accounted for 64.10%, 60.00%, 56.86%, and 68.89% of the entire seed bank in Zones A, B, C, and D, respectively. This research can promote to instruct and inform management practices in wetland protection, wetland management, and restoration and reconstruction in damaged wetlands. © 2016 Elsevier B.V.


Li W.,Chinese Academy of Forestry | Li W.,Beijing Key Laboratory of Wetland Services and Restoration | Cui L.J.,Chinese Academy of Forestry | Cui L.J.,Beijing Key Laboratory of Wetland Services and Restoration | And 10 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2015

Soil animals, a crucial part of wetland ecosystems, play an important role in nutrient cycling and energy flow and are also an important driver of wetland ecosystem succession. Research related to the diversity of soil animals is an important part of the study of soil biodiversity. Knowledge of the temporal variability of soil animal populations and species is crucial to the understanding of soil community dynamics and food webs. Lake Taihu, a shallow freshwater lake located in eastern China on the border of Jiangsu and Zhejiang provinces, was studied to document the composition, diversity, and seasonal variations of soil animal communities in a lakeshore wetland. Soil animal community structure and diversity were analyzed in four different types of lakeshore habitat: A, Rumex acetosa lakeshore; B, tree and shrub lakeshore; C, crop lakeshore; D, natural reed lakeshore. Tullgren and Baermann's methods were used to extract 3575 soil fauna individuals (ind) which were classified into four phyla, twelve classes, and 105 taxonomic groups. The density of soil animal communities was 2794.49— 67766.39 ind/ m2. Species in the phyla Arthropoda (55.75%) and Nematoda (36.27%) constituted the main body of the soil fauna. The proportion of animals in different groups varied widely from one community to another: for example, in the phylum Arthropoda, Insecta, Collembola and Arachnida accounted for 22.74%, 16.92% and 8.85% of the individuals in the soil fauna community, respectively. A test of the differences in population density of soil animal communities in different habitats indicated habitat types C and A were significantly different from habitat B (F =4.319, P < 0.05) in April 2010. In August and November 2010, the density of these communities was significantly lower in habitat A than in the other three types (F =4.331; F =6.555, P < 0.05). Also, in February 2011, the density was significantly lower than in type C and D (F =2.042, P < 0.05). At other times, no significant differences in the density of soil animal communities were observed for all habitat types (P > 0.5). The dynamics of several soil fauna community diversity indices varied in different seasons. The Simpson diversity index reached a maximum for habitat types B, C and D in April 2010, with values of 0.44, 0.59 and 0.34, respectively; meanwhile, the same index for type A reached a maximum of 0.55 in February 2011. For the Pielou evenness and Shannon diversity indices, type B, C and D reached a minimum in April 2010, while type A reached a minimum in February 2011. The Simpson diversity index difference test indicated types B and C were significantly different from type D (F =1.878, P < 0.05) in August 2010.Types A and C were significantly different for the Pielou evenness index in April 2010 (P < 0.05); and in August 2010, Type B was significantly lower than the other three types (H = 5.052, P < 0.05). Meanwhile, in November 2010, Type A was significantly lower than the other three types (F =3.271, P < 0.01) for the Shannon diversity index, and types A and C were significantly different from type D in February 2011 (P < 0.05). When combining the four types as a single measurement, the overall reserves of the soil animals were in descending order of April 2010 > November 2010 > August 2010 > February 2011. Sørensen index similarity analysis showed that the seasonal similarity of the four types of Lake Taihu lakeshore wetland soil animal communities was different. The seasonal variation had higher impact on the number of Type A dominant communities. Morisita-Horn index analysis showed that different habitat types produced different effects on the abundance of soil animal species. This suggested that seasonal change can influence the structure and composition of the soil community. The vertical distribution of the number of individuals of the soil fauna had a certain degree of accumulation, with a greater number of individuals found in the surface layer of the soil, although the exact numbers varied in different seasons. The results of this study provide a basis for health assessment and scientific management of Lake Taihu lakeshore wetland. © 2015, Ecological Society of China. All rights reserved.


Li C.,Chinese Academy of Forestry | Li C.,Beijing Key Laboratory of Wetland Services and Restoration | Chen B.,Beijing Forestry University | Zhang X.,Chinese Academy of Forestry | And 4 more authors.
Forestry Chronicle | Year: 2015

The correlation between tree-ring widths of lacebark pine and climate was investigated. Radial growth was positively correlated with monthly mean temperatures in the previous September and significantly negatively correlated with monthly mean and monthly maximum temperatures in March. There was no significant response to levels of precipitation. Treering variation was reconstructed by a transfer function using STD chronology and monthly mean temperatures. Assuming future temperature increases of 1.4 °C to 4.0 °C according to IPCC (2006), tree-ring widths would increase by 4.7% to 12.8%, and lacebark pine carbon pools would increase observably by 10.9% to 31.1%. Temperature has a positive impact on increasing biomass and hence carbon stored for lacebark pine. The results provide a theoretical reference for forest management and an evaluation of the capacity for forests to sequester carbon under climate change. © 2015 Published by NRC Research Press.

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