Canopy partitioning of precipitation into interception, throughfall, and stemflow can influence the dynamics of tree water and nutrient balances. Intercepted precipitation may evaporate back to the atmosphere or reach the forest soil via throughfall or stemflow; however, intercepted precipitation—and the minerals dissolved in the solution—may also enter the plant directly through foliar or bark uptake. Minerals deposited on canopy surfaces can be transferred along vegetation surfaces and to the soil via throughfall and stemflow. In addition to throughfall- and stemflow-mediated transport of nutrients originating from deposition, nutrients can also be leached from leaf surfaces via throughfall and stemflow. Nutrient concentrations in stemflow are typically higher than concentrations in throughfall, but throughfall volumes are much higher than stemflow volumes. Still, the majority of nutrient return to the soil occurs through leaf litter inputs and subsequent decomposition at the soil surface. Canopy partitioning of throughfall results in heterogeneous distribution of moisture which may directly or indirectly influence the heterogeneity of nutrient availability. Direct influence is based on dissolved minerals in throughfall or stemflow, whereas partitioning of throughfall may indirectly influence the heterogeneity of nutrient availability by influencing the microbial environment and community. The heterogeneity of belowground resource availability may impact fine-root density and spatial patterns of proliferation. Current knowledge is limited by a focus on how throughfall and stemflow water and nutrient pulses and patches influence individuals. We suggest that the path forward for improving our understanding of how precipitation partitioning influences tree water and nutrient balances should focus on a more holistic framework that investigates population or community level responses rather than just individual responses. Likewise, controlled manipulative experiments may prove more instructive in determining the mechanistic controls of canopy partitioning on tree water and nutrient balance than have observational studies.
Aubrey, D. P. (2020). Relevance of precipitation partitioning to the tree water and nutrient balance. In Precipitation Partitioning by Vegetation: A Global Synthesis (pp. 146–161). Springer International Publishing. https://doi.org/10.1007/978-3-030-29702-2_10