Trees : key principles in ecological land use F8
Oldeman, Roelof A.A.1; Neugebauer, Bernd2
1) Chair of Silviculture & Forest Ecology, Dept. of Ecological Agriculture,Agricultural University Wageningen, 6709 RZ WAGENINGEN, the Netherlands, 2)Trees for People, Institut f. Oekologische Landnuetzung, 79098 Freiburg,Germany.
|Trees are keys to ecological land use for three
reasons. First, they are pacemakers of sustainable development. Second, they are
spacemakers of sustainable ecosystem architecture. Third, they are placemakers for
numberless habitats hosting the diversity of life.
Pacemakers set and maintain rhythms. In agro- and silvo-systems, rhythms are set by multiple rotations of short-lived and long-lived crops. Monocropping means one rotation per large field. Ecological, mixed land use combines short, "agro-" rotations with longer "silvo-" rotations. One of these rotations is enforced as a pacemaker, e.g. by coppicing. All others are adjusted to this pacemaker as divisions or multiples.
Spacemakers build and maintain architecture. In agro- and silvo-systems, architecture is built by "layers" (structure) and "steps" (texture). Woody plants build sustainable architecture, both at the scale of a mosaic of fields, hedges and stands, and at the scale of one unit with few (agro) to many (silvo) cropping layers. One of these steps or layers is enforced as pacemaker, e.g. hedges in a mosaic or hazelnut shrubs in a farmer's forest. All other dimensions and proportions are adjusted to the spacemaker as divisions or multiples.
Placemakers boost and maintain diversity. Each organism needs a qualified place to live ("habitat"). In agro- and silvo-systems habitat diversity is boosted by complex branching of, and interaction among the largest crop species. Monocropping shows monotonous habitat patterns. Ecological, mixed land use entails very complex interactions among many structuring plant species. One species is chosen as a placemaker, e.g. Pinus species in badland forestation. All other species above and below the ground establish themselves in a complex habitat pattern adjusted to the placemaker.
These three principles of ecological silviculture suffice for designing sustainable mixed cultures, fitting in every human society. The recognition of the pacemaker principle is at the base of many transformations from "green mining" to sustainable land use.
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