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Yang L.,CAS Research Center for Eco Environmental Sciences | Wei W.,CAS Research Center for Eco Environmental Sciences | Chen L.,CAS Research Center for Eco Environmental Sciences | Jia F.,CAS Research Center for Eco Environmental Sciences | Mo B.,Gansu Academy of Forestry science
Hydrology and Earth System Sciences

Soil moisture in deep soil layers is an important relatively stable water resource for vegetation growth in the semi-arid Loess Plateau of China. Characterizing the spatial variations of deep soil moisture with respect to the topographic conditions has significant importance for vegetation restoration. In this study, we focused on analyzing the spatial variations and factors influencing soil moisture content (SMC) in shallow (0-2 m) and deep (2-8 m) soil layers, based on soil moisture observations in the Longtan watershed, Dingxi, Gansu province. The vegetation type of each sampling site for each comparison is same and varies by different positions, gradients, or aspects. The following discoveries were captured: (1) in comparison with shallow SMC, slope position and slope aspect may affect shallow soil moisture more than deep layers, while slope gradient affects both shallow and deep soil moisture significantly. This indicates that a great difference in deep soil hydrological processes between shallow and deep soil moisture remains that can be attributed to the introduced vegetation and topography. (2) A clear negative relationship exists between vegetation growth condition and deep soil moisture, which indicates that plants under different growing conditions may differ in consuming soil moisture, thus causing higher spatial variations in deep soil moisture. (3) The dynamic role of slope position and slope aspect on deep soil moisture has been changed due to large-scale plantation in semi-arid environment. Consequently, vegetation growth conditions and slope gradients may become the key factors dominating the spatial variations in deep soil moisture. Source

Yang L.,CAS Research Center for Eco Environmental Sciences | Wei W.,CAS Research Center for Eco Environmental Sciences | Chen L.,CAS Research Center for Eco Environmental Sciences | Mo B.,Gansu Academy of Forestry science
Journal of Hydrology

Soil moisture is an effective water source for plant growth in the semi-arid Loess Plateau of China. Characterizing the response of deep soil moisture to land use and afforestation is important for the sustainability of vegetation restoration in this region. In this paper, the dynamics of soil moisture were quantified to evaluate the effect of land use on soil moisture at a depth of 2. m. Specifically, the gravimetric soil moisture content was measured in the soil layer between 0 and 8. m for five land use types in the Longtan catchment of the western Loess Plateau. The land use types included traditional farmland, native grassland, and lands converted from traditional farmland (pasture grassland, shrubland and forestland). Results indicate that the deep soil moisture content decreased more than 35% after land use conversion, and a soil moisture deficit appeared in all types of land with introduced vegetation. The introduced vegetation decreased the soil moisture content to levels lower than the reference value representing no human impact in the entire 0-8. m soil profile. No significant differences appeared between different land use types and introduced vegetation covers, especially in deeper soil layers, regardless of which plant species were introduced. High planting density was found to be the main reason for the severe deficit of soil moisture. Landscape management activities such as tillage activities, micro-topography reconstruction, and fallowed farmland affected soil moisture in both shallow and deep soil layers. Tillage and micro-topography reconstruction can be used as effective countermeasures to reduce the soil moisture deficit due to their ability to increase soil moisture content. For sustainable vegetation restoration in a vulnerable semi-arid region, the plant density should be optimized with local soil moisture conditions and appropriate landscape management practices. © 2012 Elsevier B.V. Source

Wang Z.-T.,Gansu Academy of Forestry science | Yang L.,CAS Research Center for Eco Environmental Sciences | Cai G.-J.,Gansu Academy of Forestry science | Mo B.-R.,Gansu Academy of Forestry science | Chai C.-S.,Gansu Academy of Forestry science
Human and Ecological Risk Assessment

ABSTRACT: Understanding the factors that affect the health of a semi-arid region's eco-economy is necessary for its sustainable development. The health evaluation,or diagnoses,of an eco-economy at the small watershed scale requires the integrated analysis of ecological,economic,and social factors,yet few studies have achieved this. The health of an eco-economy comprises three components: vigor,organization,and resilience. We use an analytic hierarchy process to develop a health evaluation index system that evaluates the health of an eco-economy system. We then use this diagnostic method to explore the factors affecting the health status of a semi-arid loess watershed in China in 2007 and 2009. The results show that between 2007 and 2009 the health status of the eco-economy improved from the “better” stage to the “benign circle” stage. The primary productivity of grassland,land productivity,rural per capita net income,number of livestock per household,input–output ratio,commodity rate of farm produce,and labor productivity were the main factors influencing the health of this eco-economy. Furthermore,this study shows that the eco-economy depends on material input from regions outside the watershed. © 2015,Copyright © Taylor & Francis Group,LLC. Source

Chen L.,CAS Research Center for Eco Environmental Sciences | Yang L.,CAS Research Center for Eco Environmental Sciences | Wei W.,CAS Research Center for Eco Environmental Sciences | Wang Z.,Gansu Academy of Forestry science | And 2 more authors.
Environmental Management

The Chinese government initiated a massive conservation program called "Grain-for-Green" in 1999 to reduce soil erosion and improve ecosystem function. Implementing practical sustainable development in the loess plateau still remains problematic, particularly in its eco-fragile areas. Here we discussed an approach for sustainable development at the watershed scale by integrating land use suitability, ecosystem services and public participation in the loess hilly area. We linked land use scenario analysis and economic modeling to compare the outcomes of three scenarios, CLU (Current Land Use), GOLU (Grain-production Oriented Land Use) and PSLU (Potential Sustainable Land Use). The results indicated that compared to PSLU, GOLU may provide a higher economic productivity in the short-term, but not in the long-term. CLU ranked lowest in terms of economic benefits and did not meet the daily needs of the local farmers. To reconcile the land use adjustments with farmers' basic needs, a labor-saving land use strategy is necessary. Since the PSLU scenario assumes that slope cropland should be converted to pastures or orchards, more time may be available for off-farm work and for more public participation in integrated ecosystem management. Financial support to the local farmers for environmental conservation should be modulated in function of their positive contribution to ecosystem management. © 2012 Springer Science+Business Media, LLC. Source

Jiang C.-Y.,Gansu Academy of Forestry science | Zhu Z.-J.,Gansu Agricultural University | Shi Y.-H.,Gansu Agricultural University | Wu W.-J.,Gansu Academy of Forestry science | And 3 more authors.
Forest Research

Objective: To study the effects of girdling on alternate bearing of olive trees and on altering of photosynthesis in a long-term (125 days after girdling), and to investigate the changes of fruit characteristics (the rate of flower buds to lateral buds, fruit setting and fruit yield) and photosynthesis,carbohydrate and nitrogen contents in leaves. Method: Using 16-year-old 'Leccino' olive trees as experimental materials, the effects of branch girdling on fruit characteristics and leaf photosynthesis of olive trees were studied. Result: Branch girdling in semi-dormancy increased significantly the rate of flower buds to lateral buds and fruit setting (30 days after flowering) of 'On' and 'Off' olive trees, but the final fruit setting (before fruit harvest) and final fruits yield did not increase. 30 days after girdling, the concentration of soluble sugar and the rate of carbohydrate to nitrogen increased significantly, the concentration of starch increased obviously, the concentration of nitrogen, net photosynthetic rate (Pn) and stomatal conductance (Gs) decreased significantly, the intercellular CO2 concentration (Ci) changed little in 'On' and 'Off' olive trees. However, when the effect of accumulation of soluble sugar and starch in leaves after girdling had disappeared, Pn and Gs decreased significantly also, while Ci increased significantly. Also, the rate of carbohydrate to nitrogen in leaves on girdling brunches was significant higher than that on control branches, the leaf water use efficiency (WUE) was significant lower than that on control ones, which may be the reason why girdling could promote the flowering but could not promote the fruit bearing and fruits yield. Conclusion: Branch girdling in semi-dormancy may promote flowering, but may not increase final fruit yields. In a short time, the decrease of Pn after girdling attributed to end-product feedback inhibition. © 2016, Chinese Academy of Forestry. All right reserved. Source

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