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Cao S.,Northwest University, China | Cao S.,Beijing Forestry University | Ma H.,Guangxi Keyuan Engineering Consulting Co. | Ma H.,Guangxi Institute of Water Resources Research | And 2 more authors.
Biological Conservation | Year: 2014

Global environmental problems have significant natural and socioeconomic consequences. However, the consequences are often evaluated independently by ecologists and social scientists. In an effort to integrate the consequences of the two types of problem during ecological restoration and thereby improve future development of environmental policy, we used regression analysis and remote sensing to calculate the relative contributions of human activities, climate change, and socioeconomic development to land use and cover change during China's huge investments in ecological restoration since the 1980s. We performed this analysis both for China as a whole, and for eight regions with distinctive ecological and social characteristics. We found that China's fast socioeconomic development and decreasing rural population were dominant factors in ecological restoration, whereas direct human intervention was a paradoxical factor that did not always lead to recovery. However, the changes in vegetation cover and the dominant causal factors differed among the regions of China as a result of differences in local conditions. Because of the complexity of ecosystem restoration, a region-specific strategy based on integrating ecological and socioeconomic factors should be developed. In particular, we urge caution when considering single, monolithic approaches (such as the afforestation that is currently the main approach) because these approaches ignore the local limits imposed by ecological factors such as climate and soils and human factors such as socioeconomic characteristics; such approaches can be dangerous if they neglect key social or natural factors. © 2014 Elsevier Ltd.


Ma Y.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Ma Y.,China Agricultural University | Feng S.-Y.,China Agricultural University | Feng S.-Y.,Yangzhou University | And 2 more authors.
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2011

A modified Green-Ampt model (MGAM) was proposed in this study to simulate water infiltration in layered soils with entrapped air. A saturation coefficient Sa (less than 1) was introduced in MGAM to account for the effect of air entrapment on infiltration. The Sa could be approximately determined from soil physical properties. Infiltration experiments in a laboratory layered soil column and field layered soil profile were conducted to test the applicability of MGAM. For comparison, the infiltration process was also simulated by the traditional Green-Ampt model (TGAM) and the Bouwer Green-Ampt model (BGAM). The estimated Sa values by these model were very close to the measured saturation degree of soil layers at the termination of experiment. The simulation results indicate that the TGAM significantly overestimated the infiltration rate and cumulative infiltration, whereas the BGAM considerably underestimated the infiltration rate and cumulative infiltration. Furthermore, the depths of wetting front simulated by TGAM and BGAM were considerably smaller than the measured values. The comparison result shows that, the MGAM provided satisfactory simulation results, and it adequately described the infiltration process in both the laboratory soil column and field soil profile.


Ma Y.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Ma Y.,China Agricultural University | Feng S.,China Agricultural University | Feng S.,Yangzhou University | And 5 more authors.
Journal of Hydrologic Engineering | Year: 2011

Air entrapment in soil is common in cases of farmland flood irrigation or intense rain. A simple, physically based model would be more useful than the complex two-phase (gaseous and liquid phase) flow model to describe water infiltration in layered soils with air entrapment. This study proposed a modified Green-Ampt model (MGAM) to simulate water infiltration in layered soils with consideration of entrapped air. A saturation coefficient S a was introduced in MGAM to account for the resistance effect of air entrapment on infiltration. S a had robust physical meaning, and was approximately equal to one minus the plus of the residual air and residual water saturation degree that could be determined from the soil water retention curve equation. In MGAM, the actual water content and hydraulic conductivity of the wetted zone were determined by multiplying S a with the saturated values. Infiltration experiments in a 300-cm-long five-layered soil column and a 280-cm-deep eight-layered field soil profile were conducted to test the applicability of MGAM. For comparison, the infiltration process was also simulated by the traditional Green-Ampt model (TGAM), in which the wetted zone was assumed to be fully saturated, and the Bouwer Green-Ampt model (BGAM), in which the hydraulic conductivity of the wetted zone was half that of the saturated hydraulic conductivity. The estimated S a values were very close to the measured saturation degree of soil layers at the termination of the experiment. The simulation results indicated that the TGAM overestimated the infiltration rate and cumulative infiltration, whereas the BGAM underestimated the infiltration rate and cumulative infiltration. Furthermore, the depths of the wetting fronts simulated by TGAM and BGAM were considerably smaller than those measured. The MGAM provided satisfactory simulation results and adequately described the infiltration process in both the laboratory soil column and the field soil profile. © 2011 American Society of Civil Engineers.


Ma Y.,China Agricultural University | Feng S.,China Agricultural University | Su D.,China Agricultural University | Su D.,Guangxi Institute of Water Resources Research | And 2 more authors.
Computers and Electronics in Agriculture | Year: 2010

A modified Green-Ampt model was developed in this study to describe water infiltration through a 300-cm long and five-layered soil column. In the modified Green-Ampt model, a saturation coefficient was introduced to determine the water content and hydraulic conductivity of the wetted zone. The saturation coefficient was determined by the ratio between measured moisture volume and total saturated moisture volume of the wetted zone, and it should be less than 1. In this experiment, the calculated saturation coefficient was 0.8. The wetting front suction head was determined by Bouwer and Neuman methods. For comparison, the infiltration process was also simulated by traditional Green-Ampt model and HYDRUS-1D code which was based on the Richards equation. It was found that the traditional Green-Ampt model was unable to describe the infiltration process adequately. The HYDRUS-1D provided good simulation results of infiltration rate and accumulative infiltration. However, it was difficult to track the movement of wetting front along the soil profile and the corresponding root mean square error (RMSE) value was up to 57.17 cm. For the modified Green-Ampt model with Bouwer method, the RMSE values of simulated infiltration rate, accumulative infiltration and wetting front depth were 2.01E-3 cm/min, 1.28 and 8.29 cm, respectively, which were much smaller than those of traditional Green-Ampt model and HYDRUS-1D. Moreover, the modified Green-Ampt model with Bouwer method could adequately capture the infiltration rate, the accumulative infiltration and the movement process of wetting front in the large layered soil column. Therefore, it appears that the modified Green-Ampt model presented in this study is a highly effective approach to simulate water infiltration in layered soils. © 2009 Elsevier B.V. All rights reserved.


Zhao K.,Pingdingshan University | Wang Z.,Shanghai Ocean University | Lu Y.,University of International Business and Economics | Qin J.,Guangxi Institute of Water Resources Research | Tan J.,Chinese Academy of Sciences
Journal of Computational and Theoretical Nanoscience | Year: 2015

The k-vertex cover problem aims to find a vertex cover set with k vertices in a given undirected graph. Based on biological molecular computation, the paper describes a new DNA procedure to solve K-vertex cover problem in O(n2) time complexity, which greatly simplifies the complexity of the computation. Copyright © 2015 American Scientific Publishers.


Wang Z.,Shanghai Ocean University | Qin J.,Guangxi Institute of Water Resources Research | Ji Z.,China Institute of Water Resources and Hydropower Research | Huang D.,Shanghai Ocean University | Li L.,Xi'an University of Architecture and Technology
Mathematical Problems in Engineering | Year: 2015

The maximum weighted clique (MWC) problem, as a typical NP-complete problem, is difficult to be solved by the electronic computer algorithm. The aim of the problem is to seek a vertex clique with maximal weight sum in a given undirected graph. It is an extremely important problem in the field of optimal engineering scheme and control with numerous practical applications. From the point of view of practice, we give a parallel biological algorithm to solve the MWC problem. For the maximum weighted clique problem with m edges and n vertices, we use fixed length DNA strands to represent different vertices and edges, fully conduct biochemical reaction, and find the solution to the MVC problem in certain length range with O(n2) time complexity, comparing to the exponential time level by previous computer algorithms. We expand the applied scope of parallel biological computation and reduce computational complexity of practicalengineering problems. Meanwhile, we provide a meaningful reference for solving other complex problems. © 2015 Zhaocai Wang et al.


Desuo C.,Guangxi University | Desuo C.,Sanxia University | Ronghui L.,Guangxi University | Ronghui L.,Guangxi Institute of Water Resources Research
Journal of Convergence Information Technology | Year: 2012

Studies on the possible influences of water-replenishing projects on the habitat of fish along Lijiang River basin are conducted through entity physical model and water-sediment mathematical model, together with the help of acoustic fish tracking system (HTI Model 291). Studies show that under certain hydrological regime, typical fingerlings in Lijiang River such as black carp, crucian carp and silver carp have obviously different response to environmental factors such as depth of water, flow velocity, food source, light and noise, which are reflected in the routes, frequencies and scopes of the migration of fish. This experiment shows that, to some extent, the construction of upstream dams have significant impacts on the migration routes and habitat of the fish; besides the hydrological regime and biochemical indicators, environmental noise, light, vibration, water temperature and so on have significant impacts on the escape behavior of experimental fish.


Qiu L.,Guangxi Agricultural Vocational College | Qin J.,Guangxi Institute of Water Resources Research | Li R.,Guangxi Institute of Water Resources Research
International Journal of Online Engineering | Year: 2015

When sensor nodes are located around a sink node in a wireless sensor network (hereafter referred to as WSN), their energy will be consumed more quickly. Hence it's necessary to make a proper relocation of the sink node to prevent the surrounding sensor nodes from excessive energy consumption. In view of this, this paper proposes an energy-aware sink relocation (hereafter referred to as EASR) scheme, which is able to realize the adaptive adjustment on the transmission range according to the energy status of the sensor nodes in addition to the establishment of conditions for sink relocation. If the relocation condition is met, sink node will move toward the optimal direction based on the energy status of the surrounding sensor nodes. The simulation result shows that the EASR scheme proposed in this paper is able to prolong effectively the network lifetime.


Ma H.,Guangxi Institute of Water Resources Research | Zhong B.L.,Soil and Water Conservation Bureau of Changting County | Yue H.,Soil and Water Conservation Bureau of Changting County | Cao S.X.,Beijing Forestry University
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2015

Natural restoration is mainly accomplished by allowing natural reforestation to occur, combined with prohibiting agriculture and grazing to reduce human disturbance of the environment. Taking advantage of the succession that occurs in natural ecosystems is a common ecological restoration measure that can restore ecosystems and keep them in balance. However, conservation and restoration biologists have increasingly recognized that ecological communities are likely to exhibit threshold changes in structure that may prevent succession from occurring. Because long-term monitoring data are generally lacking, little is known about the consequences of such ecological thresholds for the processes of ecosystem degradation and recovery. To identify whether a degradation threshold exists that defines the boundary between the possibility of natural recovery and the need for artificial restoration of an ecosystem and to use this knowledge to support the development of a suitable strategy for environmental restoration, we have performed long-term monitoring of vegetation recovery in China’s Changting County since 1986. We found a severe problem in this area, which we refer to as the “irreversible loss of soil services”: when vegetation cover decreases below an ecological degradation threshold, leading to sustained degeneration of the vegetation community, erosion of the surface soil and declining soil fertility occur. These changes represent a severe and long-term disturbance of the vegetation, the soil, and the landscape. We identified a degradation threshold at about 20% vegetation cover, which suggests that for some sites with a vegetation cover of between 20 and 30%, vegetation cover can serve as a simple proxy for more sophisticated approaches to identifying thresholds; when vegetation cover declines to this level, restoration must start with the restoration of soil fertility and continue by facilitating vegetation development. Our results support the concept of ecological thresholds (specifically, for soil services in a warm and wet region of China) and provide a model to inform restoration strategies for other degraded ecosystems. Ecosystem restoration sometimes fails because ecological interactions are more complex or human intervention is more difficult than anticipated; factors other than human disturbance, such as climate variability (e.g., a drought shortly after planting), can result in failure of a strategy that would succeed under better conditions. Some degraded ecosystems can be sustained only through ongoing management, but many conservation efforts preclude such interventions. Although ecologists can recognize many of the species changes that are likely to precipitate threshold changes in community composition, biotic interactions can be unexpected, and because responses often depend strongly on local conditions, they cannot be broadly generalized. For example, complex ecosystems with multiple interacting species may have multiple thresholds based on different components of the ecosystem. Desertification is another example and has been shown to result from strong biogeomorphic feedbacks that operate across several spatial scales. When overgrazing of arid grasslands reduces vegetation cover, water infiltration decreases, further limiting plant growth and leading to persistent desertification. Such spatial discontinuities, called ecotones, can be detected using multivariate data ordered in one dimension through comparisons of measures of dissimilarity computed between the systems on either side of the discontinuity. The “irreversible loss of soil services” described in our study, whether at national, regional, or local scales will have a variety of thresholds, and it will be necessary to calibrate this index for different regions before it becomes a useful management tool. However, as our results show, it is possible to identify useful proxies for such thresholds and use them to guide subsequent management of degrading sites. © 2015 Ecological Society of China. All rights reserved.


Cao Y.,Beijing Forestry University | Wang B.,Beijing Forestry University | Wei T.,China National Gold Group Corporation | Ma H.,Guangxi Institute of Water Resources Research
Environmental Monitoring and Assessment | Year: 2016

Populus davidiana,Leuchtenbergia principis, and Pinus tabulaeformis are important greening tree species with a cosmopolitan distribution. However, the stoichiometric characteristics and element reserves of stands of these three species are not particularly clear. In this study, we conducted a plot-level investigation of forest stands of these species in the loess area; these have been closed forest stands more than 28 years. Trees were sampled from an area of 50 m × 20 m (in 6, 8, and 9 plots, respectively), which was sufficient for shrub (2 m × 2 m), herbal species, and litter (1 m × 1 m) investigations. The C, N, and P concentrations and the C:N:P stoichiometry in five different soil layers (0–10 cm, 10–20 cm, 20–30 cm, 30–50 cm, and 50–100 cm) and in the leaves, stems, branches, and roots of the plants were examined. The soil element concentrations and density were affected by soil depth. The element content had a significantly negative correlation with soil depth, and element density differed significantly among the soil layers. A particular element in a particular organ differed significantly between the forest stands, and the same element in different organs of the same stand was also significantly different. The C, N, and P element reserves in the soil were considerably higher than in the plants. Our results indicate that there are different stoichiometric characteristics and element reserves of the three stands in a closed forest on the Chinese loess plateau, which may provide a reference when we develop and optimize the structure of forest stands. © 2016, Springer International Publishing Switzerland.

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