草地承包中、前期放牧行为及相关生态补偿对策建模研究

Modeling the Grazing Behavior in Early and Intermediate Grassland Contract Stage and the Involved Ecological Compensation Mechanism

分析牧民的放牧行为并予以指导,有助于缓解或避免由于过度放牧导致的草地退化。利用牧草生长-消费模型,引入贴现影响,分析了牧民接手草地后的承包前期和中期放牧行为。结果显示,在承包前期,无论草地产权制度多么完善,当初始牧草生物量较高时,牧民总会采用最大放牧强度,使牧草生物量迅速下降至经济最佳牧草生物量水平。在承包中期,牧民会降低放牧强度,使牧草生物量维持在经济最佳牧草生物量水平。承包中期的放牧强度与贴现率正相关,此时的牧草生物量与贴现率负相关。为保障牧草生物量不低于一定的阈值,可以采取向牧民发放生态补偿金的经济措施,以促使牧民降低放牧强度。补偿金额是补偿系数与实际牧草生物量的乘积,补偿系数与贴现率正相关,与牧草生物量阈值负相关。

Understanding and regulating of the grazing behavior of local herdsman can be propitious to avoid overgrazing, which is regarded as the dominant driving force of grassland degradation. The grazing behavior in early and intermediate stage of grassland contract was analyzed by employing the model of growth and consumption in pasture system, into which the discount rate was introduced. The result shows that herdsmen like to maximize their grazing intensity in early grazing stage, no matter how perfect the institution of pasture property fight is. However, in intermediate grazing stage, herdsmen will lower the grazing intensity, so they can keep green biomass stable at the economicial optimalizing level. The intermediate grazing intensity is positively related to the discount rate, and the economicial optimalizing green biomass is negatively related to the discount rate. Therefore, it is possible to keep the economicial optimalizing green biomass above a given threshold by paying herdsmen ecological compensation in theory. Particularly, the monetary value can be obtained by compensation coefficient times green biomass. In addition, compensation coefficient is positively related to the discount rate,and negatively related to the threshold.