Center for subtropical Agroforestry, School of Forest Resources and Conservation, University of Florida, Gainsville, FL 32611, USA.
J Environ Qual. 2011 May-Jun;40(3):825-32. doi: 10.2134/jeq2010.0145.
Soil particle size and land management practices are known to have considerable influence on carbon (C) storage in soils, but such information is lacking for silvopastoral systems in Spain. This study quantified the amounts of soil C stored at various depths to 100 cm under silvopastoral plots of radiata pine ( D. Don) and birch ( Roth) in comparison to treeless pasture in Galicia, Spain. Soils were fractionated into three size classes (<53, 53-250, and 250-2000 μm), and C stored in them and in the whole (nonfractionated) soil was determined. Overall, the C stock to 1 m ranged from 80.9 to 176.9 Mg ha in these soils. Up to 1 m depth, 78.82% of C was found in the 0- to 25-cm soil depth, with 12.9, 4.92, and 3.36% in the 25- to 50-, 50- to 75-, and 75- to 100-cm depths, respectively. Soils under birch at 0 to 25 cm stored more C in the 250- to 2000-μm size class as compared with those under radiata pine; at that depth, pasture had more C than pine silvopasture in the smaller soil fractions (<53 and 53-250 μm). In the 75- to 100-cm depth, there was significantly more storage of C in the 250- to 2000-μm fraction in both silvopastures as compared with the pasture. The higher storage of soil C in larger fraction size in lower soil depths of silvopasture suggests that planting of trees into traditional agricultural landscapes will promote longer-term storage of C in the soil.
土壤颗粒大小和土地管理措施被认为对土壤中的碳（C）储存有很大影响，但这种信息在西班牙的林牧系统中缺乏。本研究量化了在西班牙加利西亚的辐射松（D. Don）和桦木（Roth）林牧地与无树牧场相比，在不同深度（0-100cm）下土壤中储存的 C 量。土壤被分为三个大小类别（<53、53-250 和 250-2000μm），并测定了它们以及整个（非分级）土壤中储存的 C。总的来说，这些土壤中到 1m 的 C 储量在 80.9 到 176.9 Mg ha 之间。在 1m 深度内，78.82%的 C 存在于 0-25cm 土壤深度中，25-50cm、50-75cm 和 75-100cm 土壤深度中的 C 分别为 12.9%、4.92%和 3.36%。在 0-25cm 处，桦木下的土壤比辐射松林下的土壤在 250-2000μm 大小类别中储存更多的 C；在该深度，牧场在较小的土壤部分（<53 和 53-250μm）中的 C 比松树林牧地多。在 75-100cm 深度，林牧地中 250-2000μm 土壤部分的 C 储存量明显高于牧场。林牧地中较大土壤部分在较浅土壤深度下储存更多的土壤 C，表明在传统农业景观中种植树木将促进土壤中 C 的长期储存。
