Liang Tian-gang

Estimating grassland yields using remote sensing and GIS technologies in China

Abstract From green herbage yield, environment, and remote sensing (RS) data recorded in different grassland types in Fukang County, Xinjiang from 1991 to 1996, correlation analyses and grassland yield estimates were obtained using remote sensing and geographic information system (GIS) technologies. Methods of processing images, analysing information, and linking of remote sensing data with ground grassland data were explored. Results showed correlation between fresh herbage yields and ratio vegetation index (RVI) and normalised difference vegetation index (NDVI) (P 0.679. Fresh herbage yields correlated better with RVI than with NDVI for lowland meadow, hill desert steppe, and mountain meadow, but not for plains desert steppe. Optimum non‐linear models for estimating yield were selected from six curves, and estimated total yields were verified by ground truth large‐plot investigations and statistical analyses. The effects of estimating gre...

An evaluation approach for snow disasters in the pastoral areas of northern Xinjiang, PR China

Abstract Monitoring and estimating potential snow disasters in pastoral areas of northern Xinjiang Province are important for decision‐making in hazard reduction and prevention. In this paper, four scenes of NOAA/AVHHR (Advanced Very High Resolution Radiometer) images were combined with ground observation data in the north of Xinjiang Province to establish a model for monitoring snow depth. Using a linear spectral decomposition method, the pixel‐based snow coverage and snow classification were studied. The spatial characteristics of snow, grassland, animal and climate factors were used to develop two new quantified indices for estimating the potential snow hazard grade and for integrated evaluation of snow disasters to grassland animal husbandry. The criteria for snow hazard grade and snow disaster evaluation were established. Results indicated that: (i) a pixel‐based index K1 , based on grassland yield, animal capacity, utilisable grassland area coefficient and seasonal grazing utilisation scenarios, can be quantitatively integrated to reflect the grassland capability of resisting snow disasters; (ii) the snow hazard index (K) systematically expresses the spatial and temporal changes of grassland and snow cover, and analyses, and predicts and evaluates the snow hazard grade under conditions where climatic and animal husbandry information may be unavailable during snow disasters. This index plays an important role in studies on early warning of snow hazard in pastoral areas; (iii) the integrated snow disaster evaluation index (E) and related classification criteria reflect the details of snow disaster magnitude in temporal and spatial scales, which provide the basic information for dynamic monitoring and integrated evaluation on snow disasters in pastoral areas.

Classification management for grassland in Gansu Province, China

Abstract Grassland is multi‐functional. On the basis of the different functions performed by different grassland types, and regional development demands for grassland functions, the classification management concept of grassland was designed to ensure the sustainability of grassland ecosystems. Principles, financial mechanisms, and properties of classification management are introduced in this paper. To aid management of grassland, Gansu grassland is classified into two main management sectors. One is conservation grassland, mainly devoted to ecological and social values; the other is productive grassland, where attention is focused on economic benefits through moderate or intensive production, and contributing to social value by income generated. Conservation grassland makes up 6.05 × 106 ha, or 38% of Gansu Province. Productive grassland is 10.02 × 106 ha, 62% of Gansu Province, in which 8.93 × 106 ha is moderately grazed grassland and 1.09 × 106 ha is intensively grazed grassland. Management strategies are proposed for conservation and productive grassland respectively. Absence of grazing and cropping is predominant in the management of conservation grassland, to restore degenerated areas and protect grassland with important ecological value from destruction, and further to improve the environment. Agricultural measures, such as fertiliser and irrigation, are used to enhance the productivity of intensively grazed grassland, and rotational grazing is used on moderately grazed grassland. The management of productive grassland is contracted to the managers who are given sole responsibility for its profitability. The Government finances the conservation grassland in the China West Development.

A GIS‐based expert system for pastoral agricultural development in Gansu Province, PR China

Abstract This paper describes the research methods, basic design, contents and structure of database, model base, knowledge base and major functions of an expert system for Gansu Pastoral Agricultural Development (GPAD). The system, created at Lanzhou University, can show users the knowledge, experience, and techniques accumulated by pastoral agriculture specialists, both in theory and practice over many years. This is achieved using multimedia information (e.g., text, graphics, pictures, and video), as well as expert system, network, Geographic Information System (GIS) and remote sensing (RS) technologies. The system includes 19 spatial databases related to agricultural resources and ecological environments, and 540 images of grassland species and grassland landscapes. It is composed of five major modules including cultivation of productive or ecologically important grasses and legumes, adaptability of cultivated species, vegetation classification, diagnosis of the disease, and management strategy. The eight assistant modules include: spatial database query, knowledge base query, model base query, turf establishment advice, Global Positioning System (GPS) based information, Chinas pastoral agriculture database (used for consultation on suitability of cultivated grasses, legumes, and herbs for the whole of China), literature search, and system maintenance. The system provides the answers to users’ questions related to grassland management and pastoral agriculture development in the following main areas: (i) location of a particular area of interest, (ii) natural conditions and resource base of different areas, (iii) suitability of introduced and local grassland species for different geographic areas, and (iv) suitable management strategies for pastoral agriculture development. The expert system software is a useful tool for land managers, agricultural technicians, environmental specialists, teachers, students, policy makers, land administrators and for practical advice to land users. It has an important role in improving environmental conditions and pastoral agriculture in Gansu Province and western China.

Comparing interpolation techniques for annual temperature mapping across Xinjiang region

Interpolating climatic variables such as temperature is challenging due to the highly variable nature of meteorological processes and the difficulty in establishing a representative network of stations. In this paper, based on the monthly temperature data which obtained from the 154 official meteorological stations in the Xinjiang region and surrounding areas, we compared five spatial interpolation techniques: Inverse distance weighting (IDW), Ordinary kriging, Cokriging, thin-plate smoothing splines (ANUSPLIN) and Empirical Bayesian kriging(EBK). Error metrics were used to validate interpolations against independent data. Results indicated that, the ANUSPLIN performed best than the other four interpolation methods.