Replication Data for: Opportunities for sustainable intensification of coffee agro-ecosystems along an altitudinal gradient on Mt. Elgon, Uganda

During the months of April and May 2014, vegetation structure was measured on the 150 selected plots. The altitude and plot boundary coordinates were recorded using Garmin eTrex GPS. Plot size was calculated based on plot boundary coordinates in R Statistics (R Core Team, 2014) using the sp package (Pebesma and Bivand 2005). The number of coffee trees, banana mats and stems, and shade trees were counted on the entire plot and densities (in number per ha) were calculated. Shade tree species were identified and the number of species per plot recorded. The canopy closure as an indicator for average plot- level shade was estimated using a Forestry Suppliers spherical crown densiometer (convex model A) according to Lemmon (1957) at four positions within the plot. Coffee yields were obtained through farmer recall per plot of the various harvests of the year and provided as coffee cherries or parchment, which was then converted into green been. The cumulative annual production was divided by the plot size and number of coffee trees to obtain green bean yield per hectare and green bean yield per coffee tree, respectively. The recall data was obtained using triangulation questions by an experienced local team, which proved to be successful in previous studies (Van Asten et al., 2011a; Wang et al., 2015). This allows a wide coverage of yield data. Data on age of the coffee trees, coffee management, and livelihood characteristics were obtained through structured farmer interviews during farm visits.2014年4月至5月期间，研究人员对选定的150个样地（plot）开展植被结构测定工作。利用Garmin eTrex全球定位系统（GPS）记录样地海拔与样地边界坐标。基于样地边界坐标，借助R统计软件（R Statistics，R核心团队，2014）中的sp包（Pebesma与Bivand，2005）计算样地面积。在整块样地内统计咖啡树、香蕉株丛与假茎以及遮荫树的数量，并计算其密度（单位：株/公顷）。完成遮荫树物种鉴定，并记录每个样地的遮荫树物种数量。采用Forestry Suppliers生产的球面冠层密度仪（凸面A型，Lemmon，1957），在样地内4个测点估测冠层郁闭度，以此作为样地平均遮荫程度的指示指标。咖啡产量数据通过农户回忆获取，内容为各样地当年度各次采收的产量，原始记录形式为咖啡鲜果或羊皮纸咖啡豆，随后将其转换为绿咖啡豆。将年度累计总产量分别除以样地面积与咖啡树数量，即可得到单位公顷绿咖啡豆产量与单株咖啡树绿咖啡豆产量。回忆式数据由经验丰富的本地团队采用三角设问法收集，该方法在既往研究中已被证实可行（Van Asten等，2011a；Wang等，2015），由此可实现产量数据的广覆盖采样。咖啡树树龄、咖啡种植管理方式以及农户生计特征数据，则通过农场走访时开展的结构化农户访谈获取。