Relationships between shoot size and branching patterns in 10 broad-leaved tall tree species in a Japanese cool-temperate forest

Abstract

Within-tree variations in branching patterns (the patterns of daughter shoot production by mother shoots) are the basis of tree architectural plasticity and, therefore, were studied in 10 cool-temperate broad-leaved tall tree species including three species with distinct short shoots. The relationships between mother shoot length versus branching patterns (i.e., the number and size of daughter shoots) were quantified for each species using regression equations. The number and stem length of daughter shoots were greater on longer mother shoots, although the majority of daughter shoots were short on mother shoots of any size. The magnitude of lateral spread of the mother shoot – daughter shoot system relative to that of its main axis extension increased with increasing mother shoot length, indicating weaker apical control on longer mother shoots. Among species, the lower limit of daughter shoot length was shorter and the frequency of short daughter shoots was greater on mother shoots of species with more distinct short shoots. This indicates that species with distinct short shoots effectively avoid branch overcrowding by minimizing daughter shoot extension. Differences in branching patterns among mother shoots of different sizes are discussed in relation to their functional importance for tree architectural development.