流域农业土地生态价值内涵及应用分析

Agro-ecosystem value connotation based on watershed land use

农业生态系统服务价值与其他产品生产密切相关。生态系统作为生产输入会提供服务价值,而其通常被看作购置性投入的替代品,利于成本降低。农业生态系统保护与粮食产量增加存在动态均衡,两者具有"下跌"关系。农业生产者为实现土地利用层面的利润最大化,对生态系统服务的更大依赖将导致农田产量削减。通过构建农业生态系统生产函数模型,合理确定替代条件和产出结果,量化研究种植土地保留数量与提供生态系统服务土地数量的分配比例。以永定河上游流域为典型区,借助用于生产的土地产量弹性计算,流域每增加1%的生态系统服务用地,对应农作物产量将缩减2.7%。虽对农业生态价值"下跌"影响从微级视角给出量化分析模型,但对生产中生态保护政策影响的研究仍需深化。

The service value of agro-ecosystem is closely related with other product production. The ecosystem can provide service value, which is usually considered as the substitute of purchasing input, in order to benefit the cost reduction. There is dynamic equilibrium between agricultural ecosystem protection and grain output increase, and they have the＂falling＂relation. In order to maximize profits at the level of land utilization, higher dependence of agricultural producers on ecosystem service will reduce farmland output. In this paper, the production function model of agricultural ecosystem is built so as to reasonably determine the alternative conditions and output results, and quantitative research of allocation proportion between the land reserved and the land providing ecosystem service is conducted. Taking the upstream of Yongding River basin as the study region, the calculation is conducted by means of the elasticity in land yield for production. If the land providing the ecosystem service in the river basin is increased by 1%, the corresponding crop output will be reduced by 2.7%. The quantitative analysis model is given from the micro-level perspective of the“falling”influence of agricultural ecological value, but the research in the influence on environmental protection policies in production shall be strengthened. While there are certainly instances that the interests of agro-ecosystem production and conservation may be aligned, such“win–win”outcomes are typically limited to a certain range of the production vs. conservation space. As literature analysis, some other authors have noted that the characteristic of the interaction between natural and purchased inputs may have important implications for agro-ecosystem conservation policy. The ecosystem services’ value often rests on“natural”inputs;when the price of purchased inputs goes up, more land will be conserved to provide ecosystem services. In agro-ecosystems, the changes in the land for planting may also have a dynamic feedback effect on the incentive prices, and the agriculture incentives influence the ecosystem services through motivating the changes in land use and management. Co-benefits and trade-offs can occur over multiple spatial and temporal scales. A typical＂falling＂in agro-ecosystems is the function of supporting, regulating, habitat and cultural services provided by natural ecosystems, which are substituted for food, fiber and livestock products. This reduction in output will be translated into an increase in agricultural products’ prices, as well as greater pressure to produce in other places, as a result, reducing the incentives for other producers to rely more heavily on the ecosystem services in production. At present, the incentives such as payments for ecosystem services are increasingly used to rebalance the supply of non-marketed services. Agro-ecological compensation can eliminate the negative impact of current agricultural production and guarantee the smooth environment-friendly agricultural production. Ecological values are largely influenced by the spatial and temporal dynamic variations and the accurate calculation of input costs and agricultural output remains a challenge. Competitive land utilization and the wide application of pesticides and chemical fertilizers can affect stable and efficient agricultural production, reduce the protein content of crops, and increase the probability of food pollution. Therefore, these magnitudes are so important argues for giving agro-ecosystem protection policy when considering the implications of an ecosystem service approach in future.