松嫩平原农牧交错区牲畜放牧场的空间转移

Spatial transference of grazing space in the ecotone between agriculture and animal husbandry in the Songnen Plain

研究了松嫩平原农牧交错区牲畜放牧场空间转移动态、不同放牧场对当地畜牧业的贡献率。研究结果表明 :松嫩平原农牧交错区的牲畜放牧场月际变化很大 ,草地、防护林草地和农田在不同阶段是牲畜的主要放牧场 ;牲畜放牧场具有明显的空间转移现象 ,总体趋势为农田 (1～ 3月份 )→草地 (4～ 6月份 )→防护林草地 (7～ 10月份 )→农田 (11～ 12月份 ) ;3种放牧场在不同时期对畜牧业的贡献率变化也很大 ,其变化趋势与放牧场空间转移趋势基本一致 ;草地、防护林草地和农田对松嫩平原农牧交错区畜牧业均起着重要作用 ,贡献率大小分别为农田 (38.8% ) >防护林草地 (31.8% ) >草地 (2 9.4 % )。草地在当地畜牧业中的地位明显下降 ,农田和防护林草地对当地畜牧业的贡献已相当重要。因此 ,应加强松嫩平原农牧交错区防护林草地放牧和农田放牧研究 ,在保护防护林的基础上合理利用防护林草地和杨树叶资源 ,充分利用农田杂草和农田残茬 ,增加可获得性牧草资源 ,促进地区畜牧业发展。

The phenomenon of transference of grazing space is universal in a number of ecosystems. People had been aware of and had extensively investigated it in the past decades. Ecotone between agriculture and animal husbandry in the Songnen Plain, northeast china, bears many of heterogeneous landscapes, such as typical grassland, protective plantation, and farmland. The mosaic distribution of these kinds of landscape reduces the area of typical grassland, leading to evident or obvious to some extent spatial transference of grazing space in this region. In the past few years, along with the increase of the number of livestock and degradation or salinization of typical grassland, more and more grassland, such as Leymus chinensis, is already unsuitable to graze, resulting in that the production of typical grassland can not meet the increasing forage demand of livestock. Therefore, those primary landscapes (including typical grassland, grassland under protective plantation and farmland) become the main and important grazing space of livestock in the ecotone between agriculture and animal husbandry in the Songnen Plain. Although grassland under protective plantation or farmland is playing an increasingly important role in the development of stock- breeding in this region, relatively little is known about how much contribution of grassland, grassland under protective plantation and farmland to stockbreeding and how to quantify them. Of course, people know little about what time the spatial transference of grazing space takes place and what is the route of spatial transference of grazing space to different livestock. Moreover, to accelerate the development of stockbreeding in this region, it is essential to make clear the contribution ratio of different grazing space, the current situation of spatial transference of grazing space, and their transfer time and route of grazing space. The aim of this study is to discuss these questions mentioned above. We conducted an investigation to explore the spatial transfer dynamics of grazing space and the respective contribution ratio of various grazing space to native stockbreeding in the ecotone region. Results indicated that monthly dynamics of grazing space among different kinds of livestock change significantly; there is significant differences in the selection of grazing space among different kinds of livestock; grazing space of sheep is limited mainly by growth season of crop, but grazing space of cattle is limited not only by growth season of crop and spatial character of grazing space, but also by the number of cattle flock, so that its grazing space is relatively less in grassland under protective plantation when the number of cattle flock is more than ten. Furthermore, typical grassland, grassland under protective plantation and farmland may become the most important gazing space to various livestock in different months, i.e., an evident spatial transference of grazing space exists. The main tendency is farmland (January to March)→typical grassland(April to June)→grassland under protective plantation(July to October)→farmland (November to December). The limiting factor of availability to livestock, such as the growth season of crop in farmland, dynamics of grass production in different season in grassland, and spatial character of protective plantation (such as size, length) in grassland under protective plantation, is different evidently among different grazing space. The contribution ratio of various landscapes in different months also changes significantly and its main tendency is similar to spatial transference of grazing space. Grassland, grassland under protective plantation and farmland in the ecotone also play important roles in the development of regional stockbreeding, and the total contribution ratio of different grazing space is 38.8% in farmland, 31.8% in grassland under protective plantation, and 29.4% in grassland per year. The role of grassland in stockbreeding is not dominant, and farmland and grassland under protective plantation are becoming more important. Due to