西藏高原农牧系统耦合发展及其生态效应

Coupling Crop Farming and Pastoral System for Regional Development and Their Ecological Effects on the Tibetan Plateau

生态安全屏障建设和促进农牧民持续增收是西藏高原可持续发展过程中面临的两方面重大需求。文章根据西藏地域分异的特点,对藏北地区草地面临的主要生态问题以及高原地区农牧民面临的增收困境进行了分析,提出了农区和牧区互动耦合的区域发展对策。即利用西藏"一江两河"河谷农区丰富的水热和土地条件,建设草产品和饲料基地,实施"南草北上"工程,对藏北地区的牲畜进行季节性补饲,缓解草畜矛盾,遏止草地退化,不仅可以改善藏北草地的生态环境,同时还可以增加农牧民的收入,从而实现西藏高原生态环境保护和农牧民收入增加的双赢。

Tibet Autonomous Region of China, as central part of the Qinghai-Tibetan plateau, average elevation above 4000 m, is one key zone for ecological sheltering function to China and East Asia. Nevertheless, the ecological capacity of the Tibetan plateau is lower due to their extreme environment and abominable natural resources. And, the Tibetan plateau is among those areas that are most sensitive and vulnerable to future climate change, addition with increasing human activities, such as overgrazing, many ecological problems including ecosystem degradation emerged on the Tibetan plateau, which will inevitably weaken the ecological sheltering function on the Tibetan plateau.On the other hand, poverty still widespreads on the Tibetan plateau due to inadequacy of natural resources and rigorous environment.Therefore, how to increase income of the local farmers is another important problem. Although the average income of local famers increased from 1 691 RMB in 2003 to 7 359 RMB in 2014 on the Tibetan plateau, it is still lower than national level, and about 45.7×104 local people lives below the national poverty line standard. The government aims to increase the local framer＇s average income equal to national level in year 2020. In summary, both strength the ecological sheltering function and increase income of famer and herdsman are pressing tasks on the Tibetan plateau. Therefore, the road to sustainable development and ecological civilization on the Tibetan plateau should be conserving the natural environment friendly. And, the increasing income of local farmers mainly comes from agricultural and pastoral because the traditional husbandry supported by alpine grassland ecosystem still dominated on the Tibetan plateau.Obvious functional differences exit between the pastoral system and crop farming system on the Tibetan plateau. The pastoral system distributes above 4000 m, mainly includes the Nagqu and Nagri prefecture, and this region locates at the highest area, which is important for ecological sheltering function in China. Dominated ecosystems include the alpine meadow, steppe, and desert, their natural productivity is limited and the edible forage is lower than 100kg/mu. The shortage of forage, especially in non-growth season, restricts the development of livestock farming. The contradiction between the forage supply and livestock demand will inevitably bring damage to natural grassland ecosystem. The crop-farming system distributed about 3 000–4 000 m, along the dominated river basin of Yarlung Zangbo river, Lhasa river, and Nyangqu river, mainly includes the Lhasa, Xigaze, Shannan prefecture. This area has the advantage climate and enough fields for crop farming, and their productivity of forage is about 3 000 kg/mu, which far higher than that of natural grassland in northwestern Tibetan plateau,while the current single grains planting structure limits the increase of local farm＇s income.We suggest that the ways to deal with this situation should couple pastoral system and crop farming system in different areas to realize the double win for increasing farmer＇s income and guarantee the ecological sheltering function on the Tibetan Plateau. This engineer mainly is to produce forage in crop farming system and to supply the forage to pastoral ecosystem for reducing the overgrazing in natural grassland. Based on ensuring the crop demand for the local people, some crop field can shift to artificial pasture for producing more forage in the crop framing area. The forage can be proceed to some products and transferred to pastoral area, supplied for livestock demand during natural forage shortage, therefore decrease the forage-livestock contradiction and protect the natural grassland. The local farmer also can increase more income through produce forage product. Therefore, coupling pastoral system and crop farming system not only can increase the average farmer＇s income but also facilitate to strength the ecological sheltering function of natural grassland, which is one sustainable development way on the Tibetan plateau.