Effects of extensive forest management on soil productivity

This paper focuses on the effects of extensive forest management on soil pr oductivity, its capacity to produce plants. Forest productivity, the summat ion of the productivities of the individual landscape elements (stands) tha t comprise the forest, is the integration of soil productivity, climate, sp ecies composition and stocking, and stand history. Extensive forest managem ent can be operationally defined by the monetary investment per unit area o f land, or by the number of stand entries per rotation, or by a combination of those metrics. A stand entered once during a rotation, for harvest, is extensively managed while a stand that has been subjected to site preparati on, planted with genetically improved stock, and thinned and fertilized is intensively managed. The distinction blurs between those extremes. Many rev iews have summarized the effects of forest harvest, the major extensive man agement activity, on soil properties and hence on productivity. Rather than simply reiterating those reviews, I have framed the paper in a series of a xioms (which all agree upon), corollaries (consequences to productivity tha t follow from the axioms and are also agreed upon), and postulates (propose d consequences that are subject to some uncertainty). It is axiomatic that forest management activities alter soil physical, chemical, and biological properties. Changes have been well-documented, although their intensity and duration varies among locations and associated soil and forest types. Cons equences of the changes in soil physical properties are clearly corollaries , and include reduced productivity due to surface erosion, mass flow, soil compaction, and rutting and puddling. Although the negative consequences of roads and skid trails to stand-level productivity may be considered to be corollaries, extrapolations of those consequences to the landscape is less clear and should be considered to be postulates. Similarly, consequences of changes in soil chemical and biological properties due to forest managemen t should be considered to be postulates; not fully tested. Although soil ch emical and biological properties are changed by management, the duration of those changes and their influence on productivity are not clear. Forest ec osystems are dynamic and resilient. Assessment of the consequences of chang es in properties should recognize that shifts in preferred species may not be equated with changes in soil productivity, and that short-term effects m ay not be indicative of longer-term effects. Both ethical and economic cons iderations demand good stewardship of our natural resources. Extensive fore st management, if carried out with both wisdom and prudence, is not antithe tical to good stewardship. (C) 2000 Elsevier Science B.V. All rights reserv ed.