Aboveground biomass partitioning and leaf development of Chinese subtropical trees following pruning

To evaluate the effects of pruning on aboveground biomass partitioning of trees and investigate the response of aboveground leaf mass fractions of trees to pruning, a pruning experiment with four pruning intensities (0, 20, 50, and 70%), two pruning seasons (spring and autumn), and four subtropical Chinese tree species was carried out. Pruning treatments were conducted in two successive years. In contrast to the prediction based on the pipe model theory, pruned trees partitioned more of their newly produced aboveground biomass to leaves and less to wood growth in most cases, irrespective of species and pruning seasons. This partitioning pattern was positively correlated with pruning intensity. Pruning reduced the aboveground leaf mass fractions of trees instantaneously. However, due to the increased partitioning of aboveground biomass to leaves following pruning, all pruned trees reached the same aboveground leaf mass fractions as unpruned trees within 1 year after pruning (except for Pinus massoniana after the second pruning). This unexpected biomass partitioning pattern might be attributed to the reuse of open vascular channels in stem which were formerly connected to removed branches and leaves. The increased partitioning of aboveground biomass to leaves following pruning, would benefit pruned trees to alleviate negative pruning effects and recover from the damage. (C) 2002 Elsevier Science B.V. All rights reserved.