Gansu Hydrology and Water Resources Engineering Center

Lanzhou, China

Gansu Hydrology and Water Resources Engineering Center

Lanzhou, China

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Chang Z.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Chang Z.,Gansu Hydrology and Water Resources Engineering Center | Liu X.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Liu X.,Gansu Hydrology and Water Resources Engineering Center | And 9 more authors.
Journal of Arid Land | Year: 2013

Most soil respiration measurements are conducted during the growing season. In tundra and boreal forest ecosystems, cumulative, non-growing season soil CO2 fluxes are reported to be a significant component of these systems' annual carbon budgets. However, little information exists on soil CO2 efflux during the non-growing season from alpine ecosystems. Therefore, comparing measurements of soil respiration taken annually versus during the growing season will improve the accuracy of estimating ecosystem carbon budgets, as well as predicting the response of soil CO2 efflux to climate changes. In this study, we measured soil CO2 efflux and its spatial and temporal changes for different altitudes during the non-growing season in an alpine meadow located in the Qilian Mountains, Northwest China. Field experiments on the soil CO2 efflux of alpine meadow from the Qilian Mountains were conducted along an elevation gradient from October 2010 to April 2011. We measured the soil CO2 efflux, and analyzed the effects of soil water content and soil temperature on this measure. The results show that soil CO2 efflux gradually decreased along the elevation gradient during the non-growing season. The daily variation of soil CO2 efflux appeared as a single-peak curve. The soil CO2 efflux was low at night, with the lowest value occurring between 02:00-06:00. Then, values started to rise rapidly between 07:00-08:30, and then descend again between 16:00-18:30. The peak soil CO2 efflux appeared from 11:00 to 16:00. The soil CO2 efflux values gradually decreased from October to February of the next year and started to increase in March. Non-growing season Q10 (the multiplier to the respiration rate for a 10°C increase in temperature) was increased with raising altitude and average Q10 of the Qilian Mountains was generally higher than the average growing season Q10 of the Heihe River Basin. Seasonally, non-growing season soil CO2 efflux was relatively high in October and early spring and low in the winter. The soil CO2 efflux was positively correlated with soil temperature and soil water content. Our results indicate that in alpine ecosystems, soil CO2 efflux continues throughout the non-growing season, and soil respiration is an important component of annual soil CO2 efflux. © 2013 Science Press, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg.


Qi F.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Qi F.,Shaanxi Normal University | Qi F.,Gansu Hydrology and Water Resources Engineering Center | Wei L.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Haiyang X.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute
Natural Hazards | Year: 2013

Two landscape evaluation approaches, an integrated model and an ecological analysis method, based on landscape elements and environmental quality, respectively, were used to describe land desertification in the Heihe River Basin of northwestern China, by evaluating the current state of the local ecosystems and environment. Based on national water-quality criteria and fuzzy cluster analysis methods, surface water quality was divided into 5 grades with corresponding evaluation scores (evaluation rating threshold of water pollution), while groundwater quality was divided into 5 grades based on salinity and solute chemistry. For grassland ecosystems, grass yield (biomass) and types were the main indicators used. The soil component was described according to factors including its nutrient content, thickness, texture and degree of desertification, for a total of 11 evaluation indicators. Total vegetation cover is one of the 5 indicators chosen to describe the plant ecosystem. Based on conditions currently prevailing in the study region, evaluation factors such as total output value of agricultural, industrial, forestry and animal husbandry activities, the ratio of irrigation area to farmland area, the mean output return per unit area farmland, the level of education and per capital income were selected among others to characterize the social and economic situation. In total, 32 typical environment evaluation factors were selected, classifying land desertification in the region into four zones. © 2012 Springer Science+Business Media Dordrecht.


Jianhua S.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Jianhua S.,Gansu Hydrology and Water Resources Engineering Center | Qi F.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Qi F.,Gansu Hydrology and Water Resources Engineering Center | And 3 more authors.
Journal of Arid Land | Year: 2015

Nighttime sap flow is a potentially important factor that affects whole-plant water balance and water-use efficiency (WUE). Its functions include predawn disequilibrium between plant and soil water potentials as well as between the increments of oxygen supply and nutrient uptake. However, main factors that drive nighttime sap flow remain unclear, and researches related to the relationship between nighttime sap flow velocity and environmental factors are limited. Accordingly, we investigated the variations in the nighttime sap flow of Populus euphratica in a desert riparian forest of an extremely arid region, Northwest China. Results indicated that P. euphratica sap flow occurred throughout the night during the growing season because of the partial stomata opening. Nighttime sap flow for the P. euphratica forest accounted for 31%–47% of its daily sap flow during the growing season. The high value of nighttime sap flow could be the result of high stomatal conductance and could have significant implications for water budgets. Throughout the whole growing season, nighttime sap flow velocity of P. euphratica was positively correlated with the vapor pressure deficit (VPD), air temperature and soil water content. We found that VPD and soil water content were the main driving factors for nighttime sap flow of P. euphratica. ©Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Science Press and Springer-Verlag Berlin Heidelberg 2015


Si J.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Si J.,Gansu Hydrology and Water Resources Engineering Center | Feng Q.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Feng Q.,Gansu Hydrology and Water Resources Engineering Center | And 4 more authors.
Environmental Earth Sciences | Year: 2014

Inland lakes are a major water resource for arid regions. Determining basin scale is therefore an important indicator of variability for water resources in such regions. The goal of this study was to ascertain the appropriate Juyan Lake basin scale and its minimum ecological water requirement for the lake's continued preservation. This was accomplished in three parts. First, an analysis was carried out on the inflow of the lower reach of Heihe River and any subsequent water surface area change to Juyan Lake. Second, an optimum Juyan Lake basin scale was determined by establishing existing relationships between reservoir capacity and lake area, water level and lake area, and variation in lake area during different times of the year. Third, the ecological water requirement of the lake was determined. Results showed that the decrease in surface runoff and ceased flow of the channel resulted in the drying up of the terminal lake of Heihe River. It was determined that 35.6 km2 is the most stable Juyan Lake surface area, and 0.55 × 108 m3 is the minimum replenishment quantity in which to maintain Juyan Lake throughout the year without it drying up. © 2014 Springer-Verlag Berlin Heidelberg.

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