Understanding the sustainability of social-ecological systems requires quantifying the relationships between ecosystem service supply and use. However, these relationships, and the influence of environmental change on supply and use, are poorly known. Here we apply a nested sampling design to analyse supply-use relationships in ten administrative units in each of two Eastern African regions undergoing invasion by an alien tree, Prosopis juliflora. Ecological data on supply of two key provisioning services, woody and herbaceous biomass, were collected in field plots and the use, defined here as income and livestock numbers, was assessed using household surveys. Supply and use were then up-scaled to the level of the smallest administrative unit. High Prosopis cover affected the supply of both services, with increased woody biomass but reduced herbaceous biomass. We found that supply of woody biomass was positively associated with income from wood sales. Prosopis invasion reduced income from livestock and slightly decreased cattle numbers over the past ten years. We propose that biophysical and socio-economic data collected at the same scale can help to determine supply-use relationships for ecosystem services and we discuss how integration of supply-use data can inform sustainable management of social-ecological systems in the context of environmental change.

了解社会生态系统的可持续性需要量化生态系统服务供应与使用之间的关系。但是，这些关系以及环境变化对供应和使用的影响知之甚少。在这里，我们应用嵌套抽样设计来分析两个外星人树Prosopis juliflora入侵的东非地区中每个地区的十个行政单位中的供应-使用关系。。在田间地块中收集了两种主要供应服务的生态数据，其中包括木质生物量和草本生物量，并通过家庭调查评估了其用途（在此定义为收入和牲畜数量）。然后将供应和使用规模扩大到最小的管理部门。较高的Prosopis覆盖率影响了这两种服务的供应，木质生物量增加，但草本生物量减少。我们发现木质生物量的供应与木材销售收入呈正相关。在过去的十年中，由于Prosopis的入侵，减少了牲畜的收入，并使牛的数量略有减少。