Data from: Fuelwood sustainability revisited: integrating size structure and resprouting into a spatially realistic fuelshed model

Much concern has been expressed about the sustainability of fuelwood harvesting in Africa. Most models predict that demand will outstrip supply within a few decades, resulting in severe deforestation. However, despite substantial impacts of harvesting on woody vegetation structure, the “fuelwood crisis” predicted since the 1970s has not materialized. We propose that this is at least partially because regeneration through coppicing has been poorly accounted for in most models. We developed a local fuelwood model that is demographically and spatially explicit, and that incorporates coppice dynamics. The model simulates the dynamics of multiple stem size classes (seedling, sapling, pole, and adult), the harvesting decisions of villagers based on fuelwood availability and village demand across the landscape. Importantly, we specify size-dependent coppice production of cut stems, and the probability of progression of coppice shoots into larger size classes, after accounting for self-thinning of shoots. In general, our model projections for a rural South African savanna system suggest that current levels of harvesting (barring changes in human population size) are relatively sustainable. Declines in total woody biomass were predicted to be modest (~ 20%), and the loss of intact stems of sapling size was predicted to be more than offset by increases in coppiced stems. Synthesis and applications. The results from our local fuelwood model clearly demonstrate that the impact of deforestation and wood removal on tree populations and wood resources is strongly influenced by the resprouting ability of trees. This highlights the importance of considering coppice dynamics when assessing the sustainability of wood harvesting. Our model is not system-specific, and can be transferred to other systems, with the relevant parameters and GIS layers specified. Because of the transferability of this model, it can help address key international concerns about deforestation and sustainable fuelwood management.

学界与实务界对非洲薪柴采伐的可持续性已表达诸多关切。多数模型预测，未来数十年内薪柴需求将超过供给，进而引发严重的森林砍伐。然而，尽管采伐对木本植被结构已造成显著影响，但自20世纪70年代以来被预测的“薪柴危机”始终未显现。我们认为，这一现象至少部分源于多数模型未充分考虑萌蘖更新（Coppicing）过程。

为此我们开发了一款兼具人口统计学与空间显式性的本地薪柴模型，该模型纳入了萌蘖动态过程。该模型可模拟多个茎径级的动态变化，涵盖幼苗（Seedling）、幼树（Sapling）、小径木（Pole）与成树（Adult），同时基于区域内薪柴可获得性与村落需求，模拟村民的采伐决策。尤为关键的是，我们在模型中明确了采伐木的径级依赖性萌蘖产量，以及考虑枝条自然稀疏（Self-thinning）后，萌蘖枝条向更大径级生长的概率。

总体而言，针对南非乡村稀树草原（Savanna）系统的模型预测显示，在人类人口规模不变的前提下，当前的采伐强度处于相对可持续的水平。模型预测总木本生物量仅出现小幅下降（约20%），而幼树完整茎干的损失可通过萌蘖茎干的增长得到超额补偿。

综合与应用
本研究开发的本地薪柴模型结果清晰表明，森林砍伐与木材移除对树木种群及木材资源的影响，在很大程度上受树木萌蘖能力的调控。这一结论凸显了在评估木材采伐可持续性时，纳入萌蘖动态过程的重要性。本模型并非针对特定系统开发，在指定相关参数与地理信息系统（GIS）图层后，可推广应用至其他系统。鉴于该模型具备可迁移性，其可助力解决国际社会对森林砍伐与薪柴可持续管理的核心关切。