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Zhang J.,Minqin National Research Station for Desert Steppe Ecosystem | Zhang J.,State Key Laboratory of Desertification and Aeolian Sand Disaster Combating | Zhang J.,Desert Research Institute | Liu S.,State Key Laboratory of Desertification and Aeolian Sand Disaster Combating | And 10 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2015

The non-weighing lysimeter system in the Minqin desert areas was firstly used in the 1970 s, and mainly performed the orientation research on the water consumption by the transpiration of several desert plants and the evaporation on the surface of sand, which aimed to provide the theoretical guide for the selection of afforestation density and the utilization of sand and water in Chinese sand areas. At present the system has been running for 30 years, most of the lysimeters showed the jam and leakage phenomenon, and the observation was by conventional artificial means. All the factors seriously affected the accuracy of the data monitoring. However, on the basis of the non-weighing lysimeter system structure and its testing principle, the evapotranspiration area could be extended, the capacity of testing soil column could be increased, more real natural environment conditions could be simulated and the limitations of weighing lysimeter could be overcome, in sum, the lysimeter's application field and adaptability were extended. Owing to the problems of low automation, and lack of scalability and reliability, the non-weighed lysimeter monitoring and control system in the Minqin desert areas has been retrofitted to improve its performance based on structure characteristics. The non-weighed lysimeter proving ground of 720 m2 was designed in Minqin sand areas, where 30 individual lysimeters (120 cm×120 cm) of desert plant were upgraded and 12 small groups of desert plant lysimeters (400 cm×400 cm) were expanded and built, at the same time, the lysimeter groups in different types could be used to carry out the test of water supply for plant under the constant water level of 190, 290 and 390 cm. The lysimeter proving ground upgraded and expanding-built could realize synchronous observation for evapotranspiration test from the desert plant individual scale to small group scale, and the experiment platform was provided for studying water consumption of desert plants transpiration in different scale and its coupling relationship. The distributed monitoring scheme was adopted in the new automatic monitoring system, in which the superior industrial computer was set up as the center with multiple lower machine monitoring points, such as lysimeter constant water level control and water-supplying measurement system, drainage measurement system, atmospheric precipitation monitoring system, soil moisture monitoring system, environment temperature measurement and control system, SMS cat alarm system, data remote transmission and monitoring system, and UPS over-voltage protection system, and the RS485 bus, ISM wireless communication and TCP/IP network structure were used in the system. The automatic control of the lysimeter water level, water supply and drainage, the automatic monitoring of water metering, and the soil water content were designed, and the atmospheric rainfall and the temperature indoor were monitored in real time in the new system; the system also had the functions of real-time data collection and processing, information communication and data entering, historical data storage, data report printing and remote transmission download, and the power supply system was protected against over-voltage to enhance the reliability of system operation and the stability of data acquisition. Additionally, the internet-based remote monitoring and control system was used, and the users could process the abnormal situation. According to the monitoring data analysis by the regression method, we could know that the errors of data regression analysis were ± 2.2% for the pressure sensor, ± 2.0% for the drop counter and ± 12.5% for the moisture sensors. The research extended the scale for locating observation of the desert plant and implemented the automatic monitoring for evapotranspiration of the desert plant. © 2015, Chinese Society of Agricultural Engineering. All right reserved.

Zhang J.,Gansu Agricultural University | Zhang J.,Minqin National Research Station for Desert Steppe Ecosystem | Zhang J.,State Key Laboratory Breeding Base of Desertification and Aeolian Sand Disaster Combating | Zhang J.,Desert Research Institute | And 21 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

Kumtag desert, China's sixth largest desert, lies in the south-east of the Lop Nur region,and is famous with the unique dune type of Pseudo-feathery dunes in the whole world. Kumtag desert is expanding and threatening to engulf previously productive lands with its arid wasteland character with the speed of 1-4 m eastward annually. Tamarix sand-hillocks is a frequent special biological landform types, with legible age layers structure composited by sand and plant litters, in Kumtag desert. And it is very important for regional environmental evolution research because of noting the desert environmental information diversification. In the present paper, we try to explore desert environmental change process of Kumtag desert based on stable isotope techniques collecting stable carbon isotope sample of Tamarix sand-hillocks from the different habitats and set up the stable carbon isotope series in age layers of four typical Tamarix sand-hillocks, proluvial landforms, wedland landforms, YaDan landforms and valley landforms, meanwhile environmental information and local meteorological data were collected as well. The results showed that the ratio of stable carbon isotope (δ13C), in age layers of Tamarix sand-hillocks, was fluctuated during 40-60 s of twenty century, and had declined since 1980s. The change tendency of stable carbon isotope series was accord with the stable carbon isotope downtrend of tree-ring all over the world. It was indicated that atmospheric CO2 concentration increasing affected the carbon isotope of stable carbon isotope (δ13C) in age layers of Tamarix sand-hillock. The resolution ratio(δ)of stable carbon isotope in age layers of Tamarix sand-hillocks had a similar change trendency to the global climate changes. It was dry and warm climate environment in the recent 120 years, which the resolution ratio(δ)was reduced with the global climate warming. However, the climate environment was colder and moister before the industrial revolution in the nineteenth century, and the resolution ratio(δ)was rosen. There was different response of the solution ratio δof stable carbon isotope in age layers of Tamarix sand-hillocks under different habitats to climatic elements changes. In the high altitude area, the resolution ratio (δ) in age layers was restricted by several climatic factors. e.g. air temperature, humidity, atmospheric pressure, etc. the resolution ratio(δ) composition had significantly relationship with annual air relative humidity, annual precipitation, seasonal atmospheric pressure and seasonal illumination intensity. The resolution ratio(δ) composition was affected by several climatic factors, but the hysteresis effect was not obvious. On the contrary, in the arid desert area in low elevation, the resolution ratio(δ) composition had had greatly sensitivities to annual temperature, seasonal precipitation and seasonal air relative humidity, and the hysteresis effect was obvious.

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