温性典型天然草原合理载畜量测算方法精度提高研究

Proper carrying capacity measurement has been a sceintific hotspot for grassland management in terms of the relationship of grass and livestock. With the new subsidy policy in the grassland of China implementing, this scientific problem has also attracted more and more atttention of our national scientists to carry out the research in different levels and scales. It is critical to explore the loss mechanism of grass biomass and productivity in the field for improving calculation precision of proper carrying capacity. Based on the field survey and remote sensing data, we establish remote sensing based models for different types of grassland under diffrent regions, and further select optimal models by evaluating their precisions. Model will be used to calculate continous grassland productivity, and analyze their spatial-temporal variation patterns. In order to identify the loss of grassland biomass and nutrition in the field, the productivity sample in typical grassland will be collected regularly, and dominant plant samples will be collected for nutrition analysis. Then, the proper carrying capacity will be calibarated by loss paramenter. The proper carrying capacity of different grassland in study area will be assessed by the combined constraints of inter-annual and annual stocking rate. Improving the carrying capacity measurement, and identifying proper carrying capacity of grassland to banlance the tradeoff between the ecological protection and production will provide qualified database for national subsidy grassland policy implementation and benefit the local people.

草原合理载畜量是国际上草原管理利用中关于草-畜关系研究的前沿科学问题，由于中国草原奖补政策的实施，这一科学问题成为国内从不同角度和尺度进行研究的热点。准确测定多年连续草原产草量和草原生物量在野外条件下的损耗规律，是提高天然草原合理载畜量计算精度的关键。本项目采用遥感技术和地面调查相结合，构建整合草地分类和分区域的统一测产遥感模型，进行模型精度检验、模型优选，选定的模型用于计算多年连续产草量，分析不同年份产草量的时空变化规律。在温性典型草原定时测定样地产草量，并采集优势植物样品进行营养成分的化验，揭示草原生物量和营养成分在野外条件下的损耗速率，用损耗参数校正合理载畜量计算。把年际间和年内载畜量的限定条件有机结合，评价研究区不同草原合理载畜量。改善合理载畜量的计算方法，计算在保障不同生态优先程度和生产条件下草原合理载畜量方案，为国家草原奖补政策的实施和建立美丽草原目标的实现提供科学基础数据。

放牧是中国天然草原的主要利用方式，在确保草原生态系统健康的条件下，准确测定草原合理载畜量是草原利用和保护的关键。本项目以内蒙古东部温性典型草原为研究区域，在呼伦贝尔和锡林浩特典型草原区选择自由放牧地（全年放牧）和围封样地（全年不利用），开展了全年定期野外样地采集工作。基于多年MODIS遥感数据和同期的地面样方数据，建立了多年遥感与地面产草量相结合的空间数据库，在研究区分草地类型和区域构建草原产草量遥感模型，优选了高精度和运行稳定的模型作为草原产草量测算的统一标准模型，获取了丰年、欠年和平年的产量参数，根据草原生态保护和生产的要求，计算了可供给放牧等生产活动的产草量。针对主要优势种（羊草、大针茅）进行了粗蛋白质、粗脂肪、粗纤维等营养成分的测定，计算了产草量在野外的损耗和干草营养成分的下降情况。根据草原连续遥感测产结果和草原产草量的损耗情况，在保证生态-生产等条件下，分析了不同年份合理载畜量的波动规律，评定了产草量在不同年份的合理载畜量阈值，制定了研究区保障不同生态程度条件下草地合理载畜量方案。