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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. Source

Li C.L.,State Key Laboratory of Desertification and Aeolian Sand Disaster Combating | Li C.L.,Research Station on Ecosystem of Desertification Rangeland | Li C.L.,Desert Research Institute | Xu X.Y.,State Key Laboratory of Desertification and Aeolian Sand Disaster Combating | And 8 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

Maqu alpine meadow is the important part of the Qinghai-Tibet Plateau and the main water conservation area in the upper reaches of Yellow River. But in recent years, the problems of the sandy desertification and soil erosion have become a serious threat to the ecological safety of the alpine meadow in the Qinghai-Tibet Plateau. To solve these problems, this paper examined the vegetation structure characteristics and the variation of α and β diversity on the potential, slight, moderate and serve desertification meadows in Maqu alpine meadows using sampling survey methods from July to September 2008. The results showed that in the desertification processes of Mqu alpine meadows, 1) the community coverage dropped gradually(99.216%, 80.078%, 49.895% and 36.398%, respectively), the species number also reduced gradually(53,32,14,13, respectively), community structure took a trend of simplification(the number of the dominant species were 28,16,10,8, respectively). The typical dominant and companion species of the alpine meadow also withdrew from the communities gradually, and the species adapted to the sandy environment occupied an important position in these plant communities. The typical Maqu alpine meadow ecosystem was gradually changing to the desertification alpine ecosystem, and experienced four stages, i.e.,Carex moorcroftii+Poa alpina communities→Carex moorcroftii +Saposhnikovia divaricata+Kobresia pygmaea communities→Kobresia pygmaea+Saposhnikovia divaricata+Carex moorcroftii communities→Leymus paboanus+Corispermum tibeticum+Carex moorcroftii+Saposhnikovia divaricata communities. 2)The species richness, Shannon-Wiener indexes and Simpson indexes were declining significantly. The Pielou evenness indexes and Alatalo evenness indexes showed a decreasing trend following the first increasing, and it reached the maximum in the slight desertification meadow, but their differences were not significant. The dominant index was increasing significantly, and there was extremely significant difference between the moderate desertification meadow and the slight one. 3) In terms of Whittaker index, there were extremely significant differences between the potential desertification meadow and other three ones, and there was significant difference between the moderate desertification meadow and the severe one, whereas there was no difference between the slight desertification meadow and the moderate one. 4) The community dissimilarity coefficient between the potential desertification meadow and other three ones were greater (the value in the range of 0.705-0.937), while the community common indexes between them were lower (the value in the range of 0.034-0.173), and the trend between the slight desertification meadow and the severe one was similar. However, the community dissimilarity coefficients between the moderate desertification meadow and severe one and the slight desertification meadow and the moderate one were lower (the value in the range of 0.545-0.553), and the community common indexes were higher (the value in the range of 0.293-0.303). The analysis from all the results revealed that the slight and severe desertification stages were the most important phases in the desertification process of Maqu alpine meadow. So, the potential desertification meadow must be protected and managed scientifically in order to prevent desertification from occurring. Artificial measures, e.g., enclosure, rotational grazing and tending were applied. However, in the sandy desertification meadows, vegetation restoration measures, such as turf transplantation, reseeding, fertilization as well as sand control measures must be taken to prevent the exacerbating and spreading of desertification. Source

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