The development of planting forage grass is one of the important ways to alleviate the grass-livestock conflict and entironment problem in rural Tibet. The diversity of food consumption pattern and the increase of food imported from inland areas reliefed Tibet from the pressure of food production, and provided advantage for local planting forage grass. Based on household survey data, market research data and statistical data, with the improved conceptual model of the relationship between food consumption and arable land requirement from Gerbens-Leenes et al. (2002), the potentials of sparing arable land for planting forage grass were analyzed systematically in Lhasa, Xigaze and Shannan respectively (the YLN region in rural Tibet). The analysis results of food consumption structure related to arable land requirement showed that there was a low arable land requirement of farmer diet structure in rural Tibet, which indicated the huge potential for sparing land for forage. The arable land requirement per household of Lhasa, Xigaze and Shannan was 5 542.3, 7 400.1 and 5 521.7 m2 in 2010, respectively, and the potential for forage was 4 777.5, 2 977.3 and 2 054.4 m2, respectively, which accounted for 46.3%, 28.7% and 27.1% of arable land possessed per household in Lhasa, Xigaze and Shannan, respectively. However, considering the rapid growth of population and the adverse factors of fragile ecological environment to the agricultural production in rural Tibet, the government should differentially carry out structural adjustment of agriculture and animal husbandry step by step based on the situation of agricultural production and the development level of animal husbandry of different regions in the YLN region of Tibet (Lhasa, Xigaze and Shannan), increase the enthusiasm of farmers for planting forage grass with subsidies and other incentives, establish and improve the forage grass market for forage resources allocation, alleviate local contradiction between grass and livestock, and raise income of forage grass planting in rural Tibetan.
Honghe Hani Rice Terraces System is one of the Globally Important Agricultural Heritage Systems (GIAHS) sites approved by Food and Agriculture Organization (FAO) in 2010. The system of forest-village-paddy-river in Hani terrace, which has formed over 1 300 years in history, has multiple values, including ecological value, economic value and cultural value. However, in recent years, with the development of modern agriculture and tourism, the cultivation practices for high yield and uniform variety cropping bring in serious problems there, such as ecological problems and food security problems. From the viewpoint of farming behavior, we conducted our surveys to learn about the local crop economic input-output, cultivated land resource, rural household information and local natural resources. Participatory Rural Appraisal (PRA) was used to gain the information in Yuanyang County, Yunnan Province. And Seemingly Unrelated Regression (SUR) was used to test the theoretical result on the individual peasant household level. Then, this paper summarized the status quo of crop cultivation structures and analyzed their driving factors in Hani terraces fields. The results showed as follows: 1) In the 41.23 hm2 available cultivated land referred in survey, the plants ordered by their total cultivated area are hybrid rice, maize and fruit, which rank top three in all corps. As the regional traditional crop, the cultivated area of the terrace red rice takes only 12.04% of total available cultivated land referred in survey. 2) The local rural farmer prefer hybrid rice to the terrace red rice due to its much higher economic benefits. Thus, there were more cultivate areas for hybrid rice compared to the terrace red rice. In addition, the terrace red rice is mainly cultivated in the land with poor situation, such as low quality and high altitude. Furthermore, maize is also widely cultivated there for both food and feed. 3）The economic benefit of crop, the quality and altitude of arable land have great influence on the choice of alternative crops, such as hybrid rice and red rice. As for individual peasant household, their characteristics and resource endowment have influence on choosing different corps. The family population and the altitude of cultivated land are positively correlated with the behavior of planting the terrace red rice at the 1% significance level, while the number of cooperatives is negatively correlated with the behavior of planting the terrace red rice at the 1% significance level. The conclusions of this paper is that the decrease of the traditional crop is becoming a trend in Hani terrace fields, especially for individual peasant household. If things continue in this way, it would threaten the stability and sustainability of Honghe Hani Rice Terraces System.
Northeast China, especially Heilongjiang Province, is a traditional soybean producing areas, where planting structure changes have resulted in decline in domestic soybean production. However, imports of soybean continued to rise in China, and China has become the world’s first soybean importer. To explore the planting structure changes and the main influencing factors in traditional soybean producing areas, this paper selected Nenjiang County as the study area. Firstly, interpreting TM/OLI images gave the changes of planting structure in this area; secondly, quantitative evaluation on the influence factors was made by taking soybean farmers’ willingness as dependent variable. The results show that: 1) The planting structure in the study area has greatly changed since 2000. Soybean acreage increased dramatically in the fourth accumulated temperature zone during 2000-2007. Maize planting area increased in the fourth and fifth accumulated temperature zones during 2000-2014, and has a tendency to continuously expand northward. Although soybean planting area expanded northward and eastward, its areal proportion in the total grain sown area decreased by 27% in 2014 compared to 2000. 2) The target price policy has the maximum influence on the willingness of farmers’ planting soybeans, accounting for 18.86%, followed by soybean price and crop rotation, which take 18.52%, and the impact of total investment of soybean accounts for 13.81%. The influences of other factors all count for less than 10%. The competitive advantages of domestic soybeans are “non-GMO” and “edible protein”. In addition to the policies for supporting soybean production, the country should take more important strategies to encourage the relevant enterprises to diversify the non-GMO soybean products, and strictly control the transgenic soybean in the field of food. These strategies enable reasonable premium for processing enterprises and soybean farmers and improve farmers’ production enthusiasm in traditional soybean producing area through market mechanism.
The spatial and temporal distribution of vegetation cover has undergone certain changes in the Tarim River Basin due to the impacts of comprehensive treatment project and recent climate change. Clarifying the relationship between the vegetation cover and the climate change as well as human activities can provide a scientific reference for ecological maintenance and management of Tarim River Basin. Hence, by using trend analysis, R/S analysis, partial correlation analysis and residual analysis, this study analyzed the spatial-temporal changes of NDVI in the growing season and distinguished the range and extent of the impacts of precipitation and temperature changes and human activities on vegetation cover change in the Tarim River Basin from 2000 to 2013. The results showed that: 1) The NDVI in the study area has been increasing with an average rate of 0.8%/10 a from 2000 to 2013. The changing rate in plains was significantly higher than that in mountains. The NDVI in growing season in the mountainous areas of Kaidu-Kongque River Basin and parts of the upstream and midstream of the Tarim River Basin presented obvious degradation trend. Meanwhile, NDVI in the downstream of the Tarim River Basin continued going up. 2) The vegetation cover change was mainly affected by climate change in mountain area and the temperature is the main determining factor. The increase of temperature promoted the growth of vegetation. The changes of the vegetation cover in middle-low mountains and the plain area of the mountain pass were the results of the combination of precipitation and temperature, and mainly affected by precipitation. The NDVI showed a positive correlation with precipitation and a negative correlation with temperature. 3) The increasing oasis irrigation area and the comprehensive treatment project for vegetation restoration led to the NDVI increase in the oasis. Human activities are the main driving force for vegetation growth in this area. 4) The ecological brake in the midstream of the Tarim River Basin restored the vegetation in the downstream, but it affected the water usage of the upstream and midstream to some extent. Especially for the midstream, the ecological brake led to the degradation of the vegetation with the rate of 0.1%/10 a. The relevant departments should further strengthen the reasonable allocation of the water resources and give full play to the role of the ecological brake for water resources regulation.
Glacier mass balance is the most direct reflection of climate, and its dynamic fluctuation can cause the changes of glacier morphological characteristics and melt water runoff. Usually, glacier mass balance is measured with glaciological and geodetic methods. In this study, geodetic method is used to measure the mass balance of Shiyi Glacier in the Heihe River Basin. Based on Airborne Laser Scanning (Light Detection and Ranging, LiDAR) point cloud data and SRTM (Shuttle Radar Topography Mission) DEM, we establish the process for glacier mass balance calculation. Firstly, LiDAR point cloud data are preprocessed, including filtering (classification) and interpolation. Triangulated irregular network (TIN) filtering algorithm can easily realize the point cloud data filtering to obtain precise ground point cloud data. Based on TIN filtering algorithm, we obtain the ground point cloud. And the DEM is generated from LiDAR data based on natural neighborhood interpolation method, and is resampled to the resolution of 1 m. Then, taking LiDAR DEM as the reference data, multi-source DEM data are matched with cosine curve fitting. The maximum terrain curvature of LiDAR DEM is extracted, and the spatial resolution error is corrected. After those processes, based on error analysis and accuracy assessment, we acquire ice surface change of Shiyi Glacier. Result shows the ice elevation of Shiyi Glacier changed -7.47±0.92 m from 2000 to 2012, with a glacier thinning rate of 0.62±0.08 m·a-1. According to other related studies, the volume-mass conversion parameter is assumed to be 850±60 kg·m-3. It is estimated that the average mass balance of Shiyi Glacier is -0.53±0.07 m w.e. ·a-1, and the cumulative mass change of the glacier is -6.35±0.78 m w.e., which is about (330.4±40.8) ×104 m3 water equivalents. Compared to other typical monitors on glacier mass balance, the results is reliable. The summer temperature rise in the study area caused serious mass loss of Shiyi Glacier in recent years. LiDAR point cloud data have high precision and spatial resolution, however it is less used in glacier volume research at present. In this paper, it is applied in measuring glacier mass balance changes, showing the promising prospects and practicability of both the data and the method.
The recognition and research of high-frequency dynamic snow-melting process in hinterlands of Tibet Plateau are insufficient due to the restriction of natural conditions and observation data. In this paper, every 30-minute snow depth and synchronous air temperature observation data of Maduo area in the winter of 2013-2015 are used to investigate the dynamic snow-melting processes in December, 2013 and November, 2014 and their relationship with air temperature. The results indicate that the snow melted slowly at first and then quickly during the whole snowmelt process in the winter of 2013-2014, and the snow melting process mainly occurred during 13:00-18:00. The snow melted in an uniform process during the winter of 2014-2015, and the snow melting process mainly occurred during 7:00-16:00. There is a close relationship between snow depth and air temperature. The daily maximum temperature during two winter snowmelt process were both lower than 0 ℃. The temperature three hours before the snow melting significantly affected the snow depth change. The snowmelt magnitude is mainly determined by the temperature in half an hour before the melting. There is close linear relationship between snow depth and air temperature. The two snow melting processes were close related to the variation of temperature above 0 ℃, which inferred temperature-rise process can promote snow melting.
