This paper integrates land use modeling, conservation planning, and ecosystem service valuation to estimate the benefits, costs, and feasibility of scaling up land conservation for maintaining natural water filtration in the Sebago Lake watershed, Maine, USA. We find that 79% of the watershed would have to be in permanent forest cover for water quality to be sufficiently maintained. However, we estimate that every dollar invested in conservation over the next 25 years will on average produce more than $10 in ecosystem service benefits, equivalent to about $90 million in net benefits per year, or $2,150/ha/yr. Additional sensitivity analysis on the discount rate, land acquisition cost, ecosystem service values, and development intensity reveals that benefits outweigh costs for more than 95% of the forested area, and 99% of high impact parcels. Furthermore, there is a business case for the top 50 water users to pay to conserve nearly 1000 hectares of forest per annum to avoid an increase in their water rates that could result if water quality deteriorated enough to require construction of a filtration plant. These findings suggest that it could be economically feasible to invest in forest conservation for much of the watershed.

本文将土地利用模型，保护规划和生态系统服务评估相结合，以估算在美国缅因州塞巴哥湖流域扩大土地保护以维持自然水过滤的收益，成本和可行性。我们发现，要充分保持水质，必须有79％的分水岭处于永久性森林覆盖中。但是，我们估计，在未来25年中，在保护上投资的每一美元平均将产生超过10美元的生态系统服务收益，相当于每年约9000万美元的净收益，即每年每公顷2150美元。对折现率，土地购置成本，生态系统服务价值和发展强度的其他敏感性分析表明，在超过95％的森林区域和99％的高影响地块中，收益大于成本。此外，还有一个商业案例，即前50名用水者每年需付费以保护近1000公顷的森林，以避免因水质恶化而需要建造过滤厂而导致水费增加。这些发现表明，对大部分流域的森林保护进行投资在经济上是可行的。