Certain silvicultural operations enhance the flow of ecosystem services derived from forestlands. Monetary estimates of an increased flow of such services that can impact forest management decisions are generally lacking. Here we use a growth-and-yield model to estimate physical changes in water yield and assign monetary values to these changes under different regimes of forest thinning and planting density in a loblolly pine (Pinus taeda L.) stand located in South Georgia. The model is expanded to develop corresponding measures of water yield and net present value per each management scenario. Results show an expected inverse relationship between average annual water yield and economic rent. Further, the marginal costs associated with producing an extra liter of water (per unit area) decrease as thinning intensifies and planting density declines (US$1.35/kL to US$0.72/kL under a site index of 18.3 m and US$1.20/kL to US$0.66/kL, assuming a site index of 21.3 m) relative to our baseline scenario. We emphasize that a landowner’s profits may be negatively affected by the provision of improved water yield downstream as it competes with timber extraction. Monetary payments are needed to encourage the net production of water from existing loblolly pine stands in South Georgia, United States.

中文翻译：

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估算美国南乔治亚州火炬松林额外水流的边际成本

某些造林作业增强了源自林地的生态系统服务的流动。通常缺乏对可能影响森林管理决策的此类服务流量增加的货币估计。在这里，我们使用生长和产量模型来估计水量的物理变化，并在位于南乔治亚州的火炬松 (Pinus taeda L.) 林分的不同森林疏伐和种植密度制度下为这些变化分配货币价值。该模型被扩展为针对每个管理方案制定相应的产水量和净现值度量。结果显示平均年产水量与经济租金之间存在预期的反比关系。进一步，随着间伐加剧和种植密度下降，与生产额外升水（每单位面积）相关的边际成本降低（在 18.3 m 的场地指数下为 1.35 美元/千升至 0.72 美元/千升，1.20 美元/千升至 0.66 美元/ kL，假设场地指数为 21.3 m）相对于我们的基线情景。我们强调，土地所有者的利润可能会受到下游产水量增加的负面影响，因为它与木材开采竞争。需要货币支付来鼓励美国南乔治亚州现有火炬松林的净生产水。我们强调，土地所有者的利润可能会受到下游产水量增加的负面影响，因为它与木材开采竞争。需要货币支付来鼓励美国南乔治亚州现有火炬松林的净生产水。我们强调，土地所有者的利润可能会受到下游产水量增加的负面影响，因为它与木材开采竞争。需要货币支付来鼓励美国南乔治亚州现有火炬松林的净生产水。