Data from: Are Brazil nut populations threatened by fruit harvest?

Harvest of Brazil nuts from the large, iconic tree Bertholletia excelsa generates substantial income for smallholders, providing a strong incentive to conserve the mature forests where it grows. Although much previous work has focused on the impact of nut harvest on new seedling recruits into B. excelsa populations, the connection between harvest rates and long-term population stability is still unclear. Moreover, there is additional uncertainty for Brazil nut management in terms of population response to climate change and other anthropogenic influences. We drew on 14 years of research in two sites in Acre, Brazil with different B. excelsa nut harvest intensities (39% and 81%), to produce stochastic and deterministic matrix population models which incorporated parameter uncertainty in vital rates. Adult abundance was projected to remain close to the current observed abundance or higher through the next 50 years. Elasticity analyses revealed that the asymptotic population growth rate (λ) was most sensitive to stasis vital rates in sapling, juvenile, and adult stages. Deterministic transition matrices calculated using diameter growth rates dependent on rainfall yielded average λ values around 1.0 under extreme high, extreme low, and average annual rainfall. While sustained high rates of Brazil nut harvest and climate change could potentially negatively impact B. excelsa populations, changes in human use of the forested landscape are more immediate concern. To reduce the risk of population decline, smallholders and managers of B. excelsa rich forests should focus on conservation of pre-mature and mature individuals.

从标志性大型树种巴西栗树（Bertholletia excelsa）采收的巴西坚果，可为小农户带来可观收入，进而为其原生成熟林的保护提供了强劲激励。尽管既往研究多聚焦于坚果采收对巴西栗树种群新幼苗补充的影响，但采收强度与种群长期稳定性之间的关联仍不明确。此外，巴西栗树的种群对气候变化及其他人为影响下的种群响应，也给其管理带来了额外不确定性。本研究依托巴西阿克雷州两个样地的14年研究数据，两样地的巴西栗树坚果采收强度分别为39%与81%，构建了纳入生命率参数不确定性的随机与确定性矩阵种群模型。预测结果显示，未来50年内成年个体丰度将维持在接近当前观测丰度或更高水平。弹性分析表明，渐近种群增长率（λ）对幼苗、幼龄及成年阶段的停滞生命率最为敏感。基于依赖降雨的直径生长率构建的确定性转换矩阵，在极端高降雨、极端低降雨及年均降雨条件下，得到的平均λ值约为1.0。尽管持续高强度的巴西坚果采收与气候变化或对巴西栗树种群产生潜在负面影响，但森林景观的人类利用方式变化才是更为紧迫的关注点。为降低种群衰退风险，巴西栗树富集森林的小农户与管理者应重点保护亚成熟与成熟个体。