Whole-tree rainfall interception measured directly by gravimetry and its relationship with plant traits

Rainfall interception by vegetation is influenced by rainfall characteristics, plant traits such as crown architecture and leaf area index, and the interaction between them. We determined the cumulative seasonal interception, interception loss (interception:gross precipitation) and canopy storage capacities of 7 temperate deciduous broadleaved (Acer pseudoplatanus L., Betula pendula Roth, Carpinus betulus L., Fagus sylvatica L., Populus tremula L., Sorbus aucuparia L.) and 3 evergreen coniferous tree species (Picea abies (L.) Karsten, Pinus sylvestris L., Pseudotsuga menziesii (Mirb.) Franco). Furthermore, the relationship between interception and tree traits such as crown projected area, branch angle, branch length and density and branch surface area was analysed.

Whole-tree interception was measured directly on potted trees in the Netherlands. One tree of each species had been placed on a weighing balance in an outdoor setting, thereby receiving natural rainfall. Tree size ranged from 2 to 8 m and measurements were done for 7 consecutive months.

Our results show that a) the coniferous species had larger canopy storage capacities and larger interception losses than the broadleaved species, b) the cumulative interception (in kg) of the broadleaved species was positively related to stem diameter at breast height, tree height, crown depth, maximum branch length and the total branch surface area, c) cumulative interception (in mm) of both broadleaved and coniferous species was positively related to branch number, branch length and branch surface area corrected for the respective crown projected area. These results can be used to estimate interception capacity from plant traits and to simulate interception losses of trees in a more reliable manner.