Woody Clumps and Clumpwoods

Abstract

Only the terms tree and shrub have been widely recognised for major growth forms of woody gymnosperms and dicotyledons, However many multi-stemmed woody plants do not conform to the definition of either category. For these plants it is here proposed that the term woody clump be used and that communities dominated by woody clumps be referred to as clumpwoods. Woody clumps are formed as a result of loss of apical dominance of a single stem and its replacement by several or many stems from tissue at or below ground level. Loss of apical dominance may be a genetically determined trait which is expressed early in the life of the plant or it may be a consequence of death, debilitation or physical damage to a mature mainstem. The stems of woody clumps may arise from morphologically unspecialised stem bases or from lignotubers, burls, rhizomes, branch and main stem layers, splitting and segmentation of shoot-root axes or root suckering. Woody clumps may remain as undivided individuals, with varying degrees of surface spread, or may divide by death or decay of connecting tissue to form clones. Large, undivided clumps could be called 'pre-clones'. Woody clumps are found in most major plant formations from the arctic to tropical regions and from deserts to swamplands. With a few notable exceptions such as North American aspens, the woody clump growth form has been ignored in ecological studies. We suggest in this paper that the recognition of a special term for this distinctive growth form would result in a clearer appreciation of its significance in natural and cultivated plant assemblages. Some of the genetic, ecological and management implications of woody clumps are discussed.