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Qiu G.Y.,Peking University | Zhao M.,Minqin National Station for Desert Steppe Ecosystem Studies
Journal of Environmental Monitoring | Year: 2010

Remote monitoring of soil evaporation and soil water status is necessary for water resource and environment management. Ground based remote sensing can be the bridge between satellite remote sensing and ground-based point measurement. The primary object of this study is to provide an algorithm to estimate evaporation and soil water status by remote sensing and to verify its accuracy. Observations were carried out in a flat field with varied soil water content. High-resolution thermal images were taken with a thermal camera; soil evaporation was measured with a weighing lysimeter; weather data were recorded at a nearby meteorological station. Based on the thermal imaging and the three-temperatures model (3T model), we developed an algorithm to estimate soil evaporation and soil water status. The required parameters of the proposed method were soil surface temperature, air temperature, and solar radiation. By using the proposed method, daily variation in soil evaporation was estimated. Meanwhile, soil water status was remotely monitored by using the soil evaporation transfer coefficient. Results showed that the daily variation trends of measured and estimated evaporation agreed with each other, with a regression line of y = 0.92x and coefficient of determination R2 = 0.69. The simplicity of the proposed method makes the 3T model a potentially valuable tool for remote sensing. © The Royal Society of Chemistry 2010. Source


Chang Z.-F.,Minqin National Station for Desert Steppe Ecosystem Studies | Chang Z.-F.,Gansu Province Key Laboratory of Desertification Combating | Chang Z.-F.,Desert Research Institute | Han F.-G.,Minqin National Station for Desert Steppe Ecosystem Studies | And 5 more authors.
Chinese Journal of Applied Ecology | Year: 2012

Based on the phenological data in 1974-2009 and the plot vegetation data in 2002-2010 as well as the meteorological data, this paper analyzed the responses of the vegetations in Minqin desert area to climate change. In 1961-2010, the air temperature and air humidity in the study area increased, and the increasing rate of the mean annual air temperature was greater than the global level and China's level over the past century. The responses of the vegetations to the air temperature change were mainly manifested in the advance of spring phenology, delay of autumn phenology, and lengthening of growing duration, whereas the responses of the vegetations to precipitation change were mainly manifested in the decrease of vegetation coverage and pure coverage with the decreasing precipitation. The plant density and richness fluctuated with the variation of precipitation, and the vegetation coverage and pure coverage were positively correlated with the annual precipitation firstly, and the precipitation in Jun-July and in April-May secondly. The plant density and richness were positively correlated with the precipitation in September. The advance of the spring phenology was in the order of bud-expansion > bud-opening > beginning of flowering > beginning of leaf-extension and leaf flourish > flower-bud appearance > flower flourishing > end of flowering > fruit-maturity, whereas the delay of autumn phenology was in the order of full leaf-discoloration > beginning of leaf-fall > beginning of leaf-discoloration > end of leaf-fall. As compared with the increase of air temperature in autumn, the increase of air temperature in spring had greater effects on the plant phenology in Minqin desert area. Source


Chang Z.-F.,Minqin National Station for Desert Steppe Ecosystem Studies | Chang Z.-F.,Gasu Key Laboratory of Desertification Combating | Chang Z.-F.,Desert Research Institute | Han F.-G.,Minqin National Station for Desert Steppe Ecosystem Studies | And 5 more authors.
Chinese Journal of Ecology | Year: 2010

With climate warming, the plant phenology in Northwest China desert area has an advancing trend. Based on 34-year phonological observation data of 16 plant species in the Minqin desert area of Gansu, and by using one linear trend equation, this paper analyzed the changes in the duration days of the phenology of these plant species and in the accumulated temperature in the phenological duration. With the increase of air temperature, there was an increasing trend in the duration days of the phenology. The accumulated temperature in the duration of the phenology increased significantly and spring and autumn were the more sensitive seasons in the changes of the accumulated temperature. The increase or decrease of the accumulated temperature was mainly caused by the increase or decrease of the duration days of phenology, followed by the increase of air temperature, which suggested that the duration days of the phenology of plant species could not be shortened or extended indefinitely with the increase or decrease of air temperature. Source


Chang Z.F.,Minqin National Station for Desert Steppe Ecosystem Studies | Chang Z.F.,Gansu Key Laboratory of Desertification Combating | Chang Z.F.,Desert Research Institute | Zhu S.J.,Minqin National Station for Desert Steppe Ecosystem Studies | And 8 more authors.
Journal of Arid Land | Year: 2012

Globally climates are warming. How do desert plants of different ecotypes respond to the climate change? This paper studied the differing responses to climate warming shown by desert plants of different ecotypes through analyzing the phenology and meteorological data of 22 desert plant species growing in Minqin Desert Botanical Garden in Northwest China during the period 1974-2009. The results indicate: (1) The temperature in the study area has risen quickly since 1974, and plants' growing periods became longer. The spring phenology of mesophytes advanced, and the autumn phenology of xerophytes was delayed; (2) The starting dates of spring phenophase of mesophytes and xerophytes differed significantly and both showed an advancing trend; (3) The spring phenology of mesophytes advanced by more days than that of xerophytes, whereas the autumn phenology of mesophytes was delayed by less days than that of the xerophytes; and (4) Mesophytes are more sensitive than xerophytes to rising temperature in spring and falling temperature in autumn. These findings are of value in plant management and regional introduction of different species. Source


Chang Z.,Minqin National Station for Desert Steppe Ecosystem Studies | Chang Z.,Gansu Key Laboratory of Desertification Combating | Chang Z.,Desert Research Institute | Wang Y.,Minqin National Station for Desert Steppe Ecosystem Studies | And 8 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012

The frequency of sandstorms has showed a decreasing trend with fluctuations in the Minqin desert area. In order to explore the reason for that, based on observations of sandstorms since 1956, and measured data of plant phenology since 1974, monthly variation of sandstorms was calculated with standard deviations while correlation between the frequency of sandstorms and climatic elements such as air humidity as well as plant phenology was computed with correlation coefficients. Results show that reduction in frequency of sandstorms is highly correlated with an increase in air humidity and has a certain relationship with advancing and postponing of plant phenology in spring and autumn respectively. The conclusions of this kind have not been reported so far at home and abroad. In particular, the relationship between the frequency of sandstorms and changes in plant phenology is a new finding, which needs to be verified by research in other regions. Source

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