IFRI Multiple Benefits from Forest Commons

IFRI research program is a network of collaborative research centres across North and South America, Africa, Asia, and Europe with a focus on case studies and analyses of local forest governance and forest resource outcomes in diverse socio‐political, ecological, and institutional contexts. IFRI sites are broadly representative of forests and the range of forest management regimes that exist in human‐dominated landscapes throughout the tropics (Congo Basin in Central Africa, Amazon Basin across nine Latin American countries, and Borneo across Indonesia and Malaysia). The dataset used for this analysis was drawn from the October 2018 compiled version of the full IFRI Database covering 1028 forests and villages in 26 countries. Our criteria for case selection excluded forests outside of the low‐income tropics, forests less than 5ha, and those with absent plot vegetation data. In cases where a forest had longitudinal data, we used the visit date with the most recent plot data available. These exclusions yielded a dataset of 314 forests in 15 countries located across Asia, Africa, and Latin America. Biomass, Biodiversity & Livelihoods We tested for pairwise strength of associations between our three benefits – Biomass, Biodiversity, and Livelihoods and a set of explanatory variables: Forest Size, Elevation, Population, Literacy, Food self-consumption (average number of months that households consume self-produced food), Commercial Value, Distance to market, Presence of association (Yes/No), Rulemaking (participation of local communities in making formal rules regarding governance of the forest), and Illegal Harvesting (None to Rampant). For each forest commons in our data, forest vegetation and biophysical data was collected in ~30 plots of 10 meters radius randomly distributed across the forest. We calculated the basal area of trees with a diameter greater than 10 cm at breast height. We calculated the non‐parametric Chao1 estimator of tree species richness as a proxy indicator for overall forest biodiversity using EstimateS. We measure livelihood contributions of forest commons by an index extracted through factor analysis of the proportions of (i) firewood, (ii) fodder, and (iii) timber for domestic use that each forest provides to local users. Using wards-linkage hierarchical clustering, we generated nested classes for 314 forests with Biomass, Biodiversity and Livelihoods as the component dimensions. Each cluster has observations that are similar to each other with respect to Biomass, Biodiversity, and Livelihoods, and dissimilar to forest commons in the other four clusters on the three dimensions. We divided the sample into five distinct groups; Sustainable Forests (119), Carbon Forests (23), Conservation Forests (88), Subsistence Forests (57), and Degraded Forests (27).IFRI研究计划（IFRI）是覆盖北美、南美、非洲、亚洲与欧洲的协作研究中心网络，聚焦于多样社会政治、生态与制度背景下的地方森林治理及森林资源成果的案例研究与分析。IFRI的研究样地广泛代表了全球热带人类活动主导景观中存在的森林及各类森林管理模式，包括中非刚果盆地、覆盖9个拉美国家的亚马逊盆地，以及横跨印度尼西亚与马来西亚的婆罗洲。 本分析所用数据集取自2018年10月汇编的完整IFRI数据库，该数据库涵盖26个国家的1028处森林与村落。我们的案例选择标准排除了低收入热带区域以外的森林、面积小于5公顷的森林，以及缺乏样地植被数据的森林。若某片森林拥有纵向监测数据，则选取拥有最新样地数据的调研日期。经上述筛选后，最终得到分布于亚洲、非洲与拉丁美洲15个国家的314处森林数据集。 生物量、生物多样性与生计 我们针对三项核心效益——生物量、生物多样性与生计，与一系列解释变量开展了两两关联强度检验，解释变量包括：森林面积、海拔、人口规模、识字率、粮食自给率（当地家庭消费自产粮食的平均月数）、商业价值、距市场距离、是否存在协作组织（是/否）、规则制定（当地社区参与制定森林治理正式规则的情况），以及非法采伐程度（无至猖獗）。 对于数据集中的每一处森林公共用地，我们在森林范围内随机布设约30个半径10米的样地，采集森林植被与生物物理数据。我们计算了胸径大于10厘米的树木的断面积。通过EstimateS软件计算树种丰富度的非参数Chao1估计量，以此作为整体森林生物多样性的替代指标。我们通过因子分析法，对各森林为当地使用者提供的(i)薪柴、(ii)饲料、(iii)家用木材的占比进行分析，提取得到生计贡献指数，以此衡量森林公共用地的生计收益。 采用沃德联接（Ward-linkage）分层聚类法，我们以生物量、生物多样性与生计入为维度，为314处森林生成了嵌套分类。每个聚类内的观测样本在三项维度上彼此相似，而与其余四个聚类中的森林公共用地存在显著差异。我们将样本划分为5个不同群组：可持续经营森林（119处）、碳汇森林（23处）、保护型森林（88处）、自给型森林（57处）与退化森林（27处）。