Correlated Changes in Plant Size and Number in Plant Populations

摘要: The capacity of plants to react the competitive stress their neighbours by means phenotypic plasticity has been shown in a large number experimental investigations. However, commonest fate under natural conditions is die before reaching reproductive maturity; this basic tenet Darwinian selection theory, but one which not received much attention, beyond casual observation that all seedlings survive reproduce themselves. Harper & McNaughton (1962) showed mature Papaver species, sown pure and mixed populations, becomes independent above certain density. absorb density stresses may, on other hand, be very high, so while species seemed have limit about 1000 plants/m2, Agrostemma githago found suffer no dependent mortality at densities as high 2300 plants/m2 (Harper Gajic 1961). absorbs response individual greater extent than Papaver. Sukatchew (1928), first study thinning phenomenon experimentally, Matricaria inodora, two fertilized unfertilized soils, suffered mortality; was greatest higher soil. Several passing references are made various authors plots, formal analysis process appeared series examples cited Yoda et al. (1963). They examined overcrowded populations several soils varying fertility surviving could related mean weight w = C.p-3/2, where p corresponding weight; value C varies with species. gradient line relating remains constant time proceeds. concluded from observations cultivated 'whatever factors responsible for plant size may be, age, edaphic or habitat conditions, possible maximum given average w, brought selfthinning, expected equal (C/w)2/3. If age stands were uniform, different fertilities would arranged along having -3/2 log/log co-ordinates, those more fertile soil exhibiting lower larger size.' In paper generalization extended using data derived experiments forestry management tables. Firstly an experiment specifically designed observe reported some detail. This followed analyses published studies contain sufficient relevant information construct necessary density/mean dry graphs. As preliminary example archetype these