Compaction of forest soils. A review

The problem of soil compaction in forestry differs from that in agriculture because of differences in the nature of the crop, in particular the weight and size of the plant members and the length of time that they persist. The roots compact the soil as they increase in size, but they also transmit the weight of the tree and forces generated by the wind onto the soil. There are important differences in management practices; in forestry modern harvesting machines apply heavy loads and, for reasons of cost, tend to be kept in operation throughout the year. As a consequence the structure of the soil suffers some damage, often manifested as compaction. Compaction arising from such sources may reduce the growth of the current trees or trees subsequently planted on the site. But it is difficult to predict the extent of such reduction, if any, because of the complex of interactions involved. Important factors concerned, namely, the soil water regime and the organic matter content, are emphasized. A conceptual model is proposed as a predictive tool. The mechanics of soil compaction, the effects of compaction on the physical properties of the soil, and techniques for the prevention and amelioration of compaction of forest soils, are discussed.