黄土高原典型流域农业生态系统生产力的能值分析——以安塞县纸坊沟流域为例

以黄土高原丘陵沟壑区典型小流域纸坊沟为案例,应用能值方法研究其植物初级生产力、动物次级生产力、农户经济生产力及生态系统服务生产力能值的特征及相互间的关系。结果表明:纸坊沟流域经过20年的治理,初级生产力水平有了明显提高,林草植被得到了一定恢复,巨大的生态系统服务为农业系统生产力的形成创造了基础。但整个流域依然处于低能值投入度、低耦合度、低能效的状态。主要表现为农林牧子系统之间耦合效应仍不明显;动物次级生产能值水平较低,初级生产的产品能值不能高效转化为动物次级生产能值;农户产业结构的不合理性,导致农业系统产品能值的潜在经济价值向农户现实经济收入的转化能力低下,因此,调整农户种植结构及产业配置是促进系统生产力高效转化的内在需求。

Emergy Analysis of Agroecosystem Productivity of Typical Valley in Loess Hilly-gully Region of the Loess Plateau: A Case Study in Zhifanggou Valley of Ansai County

Using data from Zhifanggou valley of fragile loess hilly-gully region, this paper studied the feature of primary plant productivity, secondary animal productivity, economic productivity of farmers and ecosystem service productivity as well as the relationships among them based on the emergy analysis method. The result showed that the primary productivity of Zhifanggou valley had been improved considerably after twenty years harnessing practices. Consequently, vegetation cover increased to some extent and the great ecosystem services created the base for the formation of the agroecosystem productivity. On the whole, however, the valley was still in the state of lower emergy input, lower coupling degree and lower energy efficiency. They are mainly reflected in the non-obvious coupling effect among various systems and the existence of the lower emergy value of the secondary aminal production. The emergy of primary production could not be transformed into the emergy of the animal production which meant that the capability of transformation from the primary production to the secondary production was lower. The irrational planting structure led to the lower capability of transformation from potential economic value of product emergy to actual economic income of the farmers. So, it is really necessary to adjust the industrial structure and allocation in order to promote the inversion among the agroecosystem productivities.