Clear-cut effects on chestnut forest soils under stressful conditions: lengthening of time-rotation

Forestry practices produce intense alterations on soil processes, which in turn could lead to more intense transformations of the system in relation to the availability of resources. From this point of view we conducted research in the critical Mediterranean environment of central Spain to check if length of time-rotation on chestnut (Castanea sativa Mill.) coppice stand allows recovery towards pre-disturbance conditions. According to the management scheme for chestnut forests in the zone, the quadrants which were clear-cut in 1957, 1967, 1982 and 1993 were used to build a chronosequence. Ten plots were allocated and physiographic, soil and forestry variables were measured to build a linear model in which the time since the last clear-felling was considered as a fixed variable. Almost all soil variables showed no significant differences between the studied stand-ages, but organic matter, nitrogen and potassium content showed an intense depletion after clear-cutting. The sustainability of this management scheme, as is shown in our results, is primarily based on the ability of chestnut trees to rapidly recover their canopy structure from rootstock as well as, from a forestry perspective, on a twofold increase in timerotation (in more mesic chestnut stands of Mediterranean Spain, clear-cuts are conducted after 20 years). Under stressful conditions of our stands, maximum productivity (20 years) does not coincide with the time to soil recovery (40–50 years) and consequently this management scheme has lengthened the time-rotation interval to guarantee viability of the stand. # 2003 Elsevier Science B.V. All rights reserved.