Agroforestry systems (AFS) are increasingly being recognized as sustainable land-use systems that can increase carbon (C) sequestration and improve food security. However, the relative contributions of various C pools to the overall C stock of AFS and their dependence on factors such as tree age, species diversity and density is still unclear in many regions. Using an equivalent soil mass approach, we investigated the effect of three different AFS (hedgerow, shelterbelt, and silvopasture) and their component land-use types (treed areas and adjacent cropland/grassland) on various C pools across 36 sites in central Alberta, Canada. On average, the treed area within AFS stored 178.5 t ha⁻¹ more C relative to adjacent cropland or grassland, although the total C stock did not differ among the three AFS types. Most of the C in the treed area of AFS was stored in the mineral soil (61%), overstory trees (28%), and the LFH (litter, partially decomposed litter and humus, 10%) layer, while midstory trees, shrubs, and understory vegetation together accounted for the remaining 1% of the C storage. The C stock size in the treed area was closely associated with tree stand characteristics of the three AFS, with the C pool size in the LFH positively related to tree age. Our results highlight that the amount of C stored in the LFH layer is substantial and should be considered when assessing C storage within AFS and suggest that investing in AFS can be an effective strategy for meeting part of Canada's C reduction goals to mitigate climate change.

农林业系统 (AFS) 越来越被认为是可持续的土地利用系统，可以增加碳 (C) 固存并改善粮食安全。然而，在许多地区，各种碳库对 AFS 总碳库的相对贡献及其对树龄、物种多样性和密度等因素的依赖性尚不清楚。使用等效土壤质量方法，我们研究了三种不同的 AFS（绿篱、防护林和林场）及其组成土地利用类型（林区和相邻农田/草地）对艾伯塔省中部 36 个地点的各种碳库的影响，加拿大。平均而言，AFS 内的树木区域存储了 178.5 t ha ^-1尽管三种 AFS 类型之间的总碳储量没有差异，但相对于相邻农田或草地的碳储量更多。AFS 乔木区的大部分碳储存在矿质土壤 (61%)、上层乔木 (28%) 和 LFH（凋落物、部分分解的凋落物和腐殖质，10%）层中，而中层乔木、灌木和林下植被一起占 C 储存量的剩余 1%。林区碳库大小与三个 AFS 的林分特征密切相关，LFH 中的碳库大小与树龄呈正相关。我们的结果强调，LFH 层中存储的 C 量很大，在评估 AFS 内的 C 存储时应予以考虑，并表明投资 AFS 可以成为满足加拿大部分地区需求的有效策略