State Key Laboratory of Earth Surface Processes and Resource Ecology

Beijing, China

State Key Laboratory of Earth Surface Processes and Resource Ecology

Beijing, China
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Liu Y.,Beijing Normal University | Liu Y.,Heilongjiang Academy of Forestry | Chen H.,Beijing Normal University | Chen H.,University of Leipzig | And 2 more authors.
Journal of Forestry Research | Year: 2017

Ectomycorrhizal (EM) networks provide a variety of services to plants and ecosystems include nutrient uptake and transfer, seedling survival, internal cycling of nutrients, plant competition, and so on. To deeply their structure and function in ecosystems, we investigated the spatial patterns and nitrogen (N) transfer of EM networks using 15N labelling technique in a Mongolian scotch pine (Pinus sylvestris var. mongolica Litv.) plantation in Northeastern China. In August 2011, four plots (20 × 20 m) were set up in the plantation. 125 ml 5 at.% 0.15 mol/L 15NH4 15NO3 solution was injected into soil at the center of each plot. Before and 2, 6, 30 and 215 days after the 15N application, needles (current year) of each pine were sampled along four 12 m sampling lines. Needle total N and 15N concentrations were analyzed. We observed needle N and 15N concentrations increased significantly over time after 15N application, up to 31 and 0.42%, respectively. There was no correlation between needle N concentration and 15N/14N ratio (R2 = 0.40, n = 5, P = 0.156), while excess needle N concentration and excess needle 15N/14N ratio were positively correlated across different time intervals (R2 = 0.89, n = 4, P < 0.05), but deceased with time interval lengthening. Needle 15N/14N ratio increased with time, but it was not correlated with distance. Needle 15N/14N ratio was negative with distance before and 6th day and 30th day, positive with distance at 2nd day, but the trend was considerably weaker, their slop were close to zero. These results demonstrated that EM networks were ubiquitous and uniformly distributed in the Mongolian scotch pine plantation and a random network. We found N transfer efficiency was very high, absorbed N by EM network was transferred as wide as possible, we observed N uptake of plant had strong bias for 14N and 15N, namely N fractionation. Understanding the structure and function of EM networks in ecosystems may lead to a deeper understanding of ecological stability and evolution, and thus provide new theoretical approaches to improve conservation practices for the management of the Earth’s ecosystems. © 2017 Northeast Forestry University and Springer-Verlag GmbH Germany


Liu X.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Liu X.,Beijing Normal University | Zhu X.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Zhu X.,Beijing Normal University | And 7 more authors.
Acta Geographica Sinica | Year: 2014

Using the daily minimum temperature data of 121 meteorological stations in Inner Mongolia and its surrounding areas, this paper analyzed the spatiotemporal variation of cold surge and its possible influencing factors in Inner Mongolia during 1960-2012, based on piecewise regression model, Sen+Mann-Kendall model, and correlation analysis. The results show that, (1) The occurrence frequency of single-station cold surge presented a decreasing trend in Inner Mongolia during recent 53 years, with a linear tendency of -0.5 times/10a (-2.4-1.2 times/10a), of which a significant decreasing trend was detected before 1991, being -1.1 times/10a (-3.3-2.5 times/10a), while an increasing trend of 0.45 times/10a (-4.4-4.2 times/10a) was found after 1991. On the seasonal scale, the trend of spring cold surge was consistent with that of the annual value, and the most obvious change of cold surge also occurred in spring. The frequency of monthly cold surge showed a bimodal structure, and November witnessed the highest incidence of cold surge. (2) Spatially, the high incidence of cold surge is mainly observed in the northern and central parts of Inner Mongolia, and higher in the northern than the central part. The inter-decadal characteristic also detected that high frequency and low frequency regions presented a decreasing trend and an increasing trend, respectively, during 1960-1990, while high frequency regions expanded after the 1990s, regions with high frequency of cold surge were mainly distributed in Tol Gol, Xiao’ergou, and Xi Ujimqin Banner. (3) On annual scale, the cold surge was dominated by AO, NAO, CA, APVII, and CQ, while the difference in driving forces among seasons was detected. Winter cold surge was significantly correlated with AO, NAO, SHI, CA, TPI, APVII, CW, and IZ, indicating that cold surge in winter was caused multifactor. Autumn cold surge was mainly affected by CA and IM, while spring cold surge was significantly correlated with CA and APVII.


He C.,State Key Laboratory of Earth Surface Processes and Resource Ecology | He C.,Beijing Normal University | Yuanyuan Z.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Yuanyuan Z.,Beijing Normal University | Anni W.,Beijing Normal University
2nd International Conference on Information Science and Engineering, ICISE2010 - Proceedings | Year: 2010

Detecting land-use/land-cover (LULC) changes in rural-urban fringe areas (RUFAs) timely and accurately using satellite imagery is essential for land-use planning and management in China. Although traditional spectral-based change-vector analysis (CVA) can offer an effective method of LULC-change detection in many cases, it encounters difficulties in RUFAs because of deficiencies in the spectral information of satellite images. To detect LULC changes in RUFAs effectively, this paper proposes an extended CVA approach that incorporates textural change information into the traditional spectral-based CVA. The extended CVA was applied to the Haidian District, Beijing, China. The results demonstrated the improvement of the extended CVA compared to the traditional spectral-based CVA: overall accuracy increased from 90.67% to 95.33%, and the kappa coefficient increased from 0.81 to 0.91. The advantage of the extended CVA lies in its integration of both spectral and textural change information to detect LULC changes, allowing for effective discrimination of LULC changes that are spectrally similar but texturally different in RUFAs. The extended CVA has great potential to be widely used for LULC-change detection in RUFAs, which are often heterogeneous and fragmental in nature, with rich textural information. © 2010 IEEE.


Guo Z.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Guo Z.,Beijing Normal University | Guo Z.,The Academy of Management | Zhang X.-N.,Beijing Normal University | And 5 more authors.
Chinese Journal of Ecology | Year: 2010

Based on the 1982-2003 GIMMS-NDVI and meteorological data, and by using GIS spatial analysis and statistical methods, the responses of vegetation phenology in Northeast China to climate change were analyzed. From 1982 to 2003, the annual mean temperature in Northeast China had an increasing trend, while the annual mean precipitation was in reverse. The elevated temperature in spring advanced the beginning dates of the growth seasons of the vegetations in coniferous forest, coniferous and broadleaved mixed forest, broadleaved forest, meadow, and swamp (P <0. 05), while the precipitation in spring only postponed the beginning date of the growth season of the vegetation in coniferous forest (P <0. 05). Temperature had less effects on the ending dates of the vegetations growth seasons except that the declined temperature in autumn advanced the ending dates of the growth seasons of grasses ( P < 0. 05). Compared with temperature, precipitation had more effects on the ending dates of the vegetations growth seasons. Due to the decreased precipitation in autumn, the ending dates of the growth seasons of the vegetations in coniferous and broadleaved mixed forest, grassland, and cropland were advanced ( P < 0. 05) while those of the growth seasons of grass-forb communities advanced \P <0. 05). The ending dates of crop growth seasons were advanced by the declined precipitation in summer and September ( P < 0. 05). The warmer temperature in spring prolonged the growth seasons of the vegetations in broadleaved forest and swamp ( P < 0. 05). The declined precipitation in spring shortened the growth seasons of shrubs (P <0. 05), while the increased precipitation in summer prolonged the growth seasons of grass-forb communities and crops (P <0.05).


Yan M.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Yan M.,CAS Institute of Botany | Zhang X.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Zhang X.,CAS Institute of Botany | And 2 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2010

Information about root respiration is essential for evaluating soil carbon cycling and sequestration in forest plantation ecosystems. Using LI-COR- 6400- 09 system, root respiration was determined in poplar plantations at three different developmental stages in Xinjiang. Based on the field observation in 2007 and 2008, the seasonal dynamics of root respiration and its main controlling factors including tree age, soil conditions and fine root biomass were analyzed. The results showed that root respiration rate of the plantations (aged from 2, 7 to 12) displayed similar seasonal patterns, with the maximum occurred in early summer and the minimum in autumn, closely followed the seasonal variation of soil temperature in the top layer. Furthermore, root respiration rate peaked earlier than soil temperature and fine root biomass in the growing season, which could imply that root seasonal phenology and belowground carbon allocation also played a role in variation of root respiration. The average root respiration in the 2-year-old stands was 3. 78 jjimol CO2m-2s -1, then declined with increasing plantation age. The contribution of root respiration to soil respiration varied from 38. 6% to 58. 0%, with the maximum occurred in the 2-year-old stands. The variability in root respiration with tree ages mainly resulted from the differents in root production, turnover and metabolism at these three stages. In sum, soil temperature and fine root biomass at top depth jointly explained 76% of variation in root respiration. Also, our results hightlight the importance of developmental stage in evaluating root respiration over a full rotation.


Yang S.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Zong L.,Tsinghua University | Wang Y.,Tsinghua University
Applied Mechanics and Materials | Year: 2011

Highway bridges played an important role in lifeline systems. Their seismic damage status made a direct influence on the implement plan of the earthquake relief work and the life and property security of the people. Therefore, accurate assessment and prediction for the seismic damage of highway bridges were of vital significance, based on which reasonable earthquake fortification could be implemented. This paper summarized and classified the existing seismic damage assessment methods for highway bridges, including certain index evaluation methods based on statistical results, vulnerability index evaluation methods based on probability theory and vulnerability index evaluation methods based on aggregation model. Then the capacity-spectrum method which could be used for calculating the fragility curve and the seismic assessment model of highway bridges used in HAZUS were specially explained. At last, the proposal for the development of seismic assessment systems related with highway bridges in China was put forward. Considering HAZUS's good performance in seismic assessment, a similar assessment system should be built in China as soon as possible. The first step should be classifying highway bridges in China based on their current situation and obtaining their seismic assessment model parameters roughly, which tend to be safe. The second step should be carrying out sufficient experiments and numerical analysis and revising the model parameters obtained in the first step. © (2011) Trans Tech Publications.


Zong L.,Tsinghua University | Shi G.,Tsinghua University | Yang S.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Wang Y.,Tsinghua University
Proceedings of the 12th International Symposium on Structural Engineering, ISSE 2012 | Year: 2012

Seismic damage of highway bridges is always a big problem, especially under the situation that the destructive earthquake often occurs in recent years. This paper is aimed to make an effort to promote the improvement of the seismic damage assessment system of China. Considering HAZUS's good performance in seismic assessment, a similar assessment method was implemented in this paper. Based on the models used in HAZUS, the classification for the highway bridges in China was done and a basic assessment model was obtained which could be used for the highway bridges in China. The prediction was checked by the statistical results of the highway bridges seismic damage under Wenchuan earthquake. It showed that the model proposed by this paper is reasonable and could provide references for the development of seismic damage assessment system in China. However, the research could be just called exploratory research because the model was not so accurate for some kinds of highway bridges with the limit of time and data. More efforts should be made to improve the model along the way described in this paper.


Zhang H.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Yuan W.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Dong W.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Liu S.,U.S. Geological Survey | Liu S.,Central South University of forestry and Technology
Ecological Complexity | Year: 2014

The seasonal litterfall plays an important role in the process of forest carbon and nutrient cycles. The current dynamic vegetation models use a simplified method to simulate seasonal patterns of litterfall, and assume that litterfall inputs distributed evenly through the year for deciduous trees or occur once during the start of year for evergreen trees. In this study, we collected more than 400 litterfall measurements for different forest ecosystems from existing literature and monographs, and analyzed the seasonal patterns of litterfall over the various forest types. The results showed that the total annual litterfall varied significantly by forest types in the range of 3-11Mgha-1y-1. The seasonal litterfall patterns had diverse forms and varied obviously among the forest types. For tropical forests, the litter peaks occurred mostly in spring or winter, corresponding to the drought season; for temperate broadleaved and needle-leaved evergreen forests, litter peaks could occur at various seasons; and for temperate deciduous broadleaved and boreal evergreen needle-leaved forests, litter peaks were observed in autumn. Global analyses showed that seasonal patterns of litterfall were determined by both the physiological mechanism and environmental variables. © 2014 Elsevier B.V.


Gu W.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Lin Y.-B.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Lin Y.-B.,China West Normal University | Xu Y.-J.,State Key Laboratory of Earth Surface Processes and Resource Ecology | And 3 more authors.
Cold Regions Science and Technology | Year: 2013

The Bohai Rim is one of the water-scarce regions in China. But every winter, more than 1billionm3 of sea ice formed in the sea, about 40% of which distributes within 10km offshore and is expected to be exploited and utilized as source of freshwater. The salinity of the Bohai sea ice ranges from 4 to 11‰, under suitable ambient temperatures, gravity driven brine drainage and flushing from the melted water can convert sea ice into freshwater ice. To study the influence of ambient conditions on the process, we conducted two experiments on the coast of the Bohai Sea from January to March in 2011. The results showed that ambient temperature was a decisive and controlling factor in gravity-induced sea ice desalination, and that insulation could affect the duration, volume and salinity of the drainage. If the ambient temperature was controlled between -4.0 and 3.0°C, the drainage would have a low volume and high salinity. With a rise in the air temperature, the volume of the drainage increased and the salinity decreased. Sea ice desalination and freshwater production were negatively correlated: the higher the freshwater production, the lower the sea ice desalination and vice versa. © 2012 Elsevier B.V.


Gu W.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Lin Y.,State Key Laboratory of Earth Surface Processes and Resource Ecology | Lin Y.,China West Normal University | Xu Y.,State Key Laboratory of Earth Surface Processes and Resource Ecology | And 4 more authors.
Desalination | Year: 2012

In winter 2009 and 2010, 9000m 3 and 12,000m 3 of sea ice, respectively, were collected from Bohai Bay and stored in a desalination pool. In 2009, the experiment lasted 80days, and produced 4500m 3 of desalinated water with the salinity of 0.8‰. By contrast, the experiment of 2010 lasted 90days and yielded 6700m 3 of water with the salinity of 1.4‰. Experimental results showed that under the force of gravity and low temperature, brine pockets within the sea ice were gradually drained out and sea ice was therefore converted from saline ice to freshwater ice. In this process, ambient temperature significantly affected drainage volume and salinity. When temperature rose, drainage volume increased and salinity decreased. Soluble salts decreased at different magnitudes during the course of gravity-induced desalination, in which chlorides showed the largest magnitude of decrease and sulfates the lowest. pH increased as a result of increasing sodium ion concentration. Insulation measures yielded higher rate of freshwater production by extending the duration of desalination. Shortening the period of desalination while maintaining high yield is worthy of further attention in studying gravity-induced sea ice desalination. © 2012 Elsevier B.V.

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