Designing forest vegetation management strategies based on the mechanisms and dynamics of crop tree competition by neighbouring vegetation
Plant interactions can be defined as the ways plants act upon the growth, fitness, survival and reproduction of other plants, largely by modifying their environment. These interactions can be positive (facilitation) or negative (competition or exploitation). During plantation establishment or natural forest regeneration after a disturbance, high light levels and, sometimes, increased availability of water and nutrients favour the development of opportunistic, fast-growing herbaceous and woody species which capture resources at the expense of crop trees. As a consequence, the growth and survival of crop trees can be dramatically reduced. Although the effects of this competition are well documented, the physical and physiological mechanisms of competition are not. Moreover, the competition process is never constant in time or space. We present a conceptual competition model based on plant growth forms common in global forests, i.e. graminoids, forbs, small shrubs, large shrubs and mid-storey trees, and main-storey trees. Their competitive attributes and successional dynamics are examined. An overview is presented on the way forest vegetation management (FVM) treatments influence these components and outcomes regarding crop tree performance and diversity conservation. Finally, a synthesis of literature yields FVM guidelines for efficiently optimizing crop tree performance and safeguarding diversity. Future research needs to further sustainable FVM are presented.