Seasonal and meteorological effects on differential stemflow funneling ratios for two deciduous tree species

- Stemflow was monitored for 5 years for tree species of contrasting physical traits.
- Funneling ratios in subcanopy trees exhibit higher rainfall scavenging efficiency.
- Interspecific stemflow response varies with canopy leaf phase and seasonality.
- Multivariate analysis shows differences in stemflow response to storm variables.
- More stemflow studies are necessary to model diverse subcanopy hydrologic response.

SummaryStemflow is an important subcanopy flux that delivers enriched rainfall to soils immediately surrounding a tree. Stemflow volume represents the quantity of this hydrologic flux while funneling ratio (FR) represents the efficiency with which individual trees scavenge water during rainfall events. Stemflow hydrology and storm meteorological characteristics were monitored from 2007 through 2012 to determine the interspecific differences in stemflow flux with a focus on FR efficiency. The objective of this study was to examine the influence of tree species and size on stemflow FR, determine how seasonality affects stemflow FR, and quantify the role of storm meteorological conditions on stemflow FR. The results presented in this paper build upon 2 years of previous hydrologic research from the Fair Hill, MD field site, which strengthen previous findings via larger storm sample size and highlight more complex stemflow hydrologic relationships than originally assumed. Specifically, this study has demonstrated (1) the efficiency with which smaller trees gain access to rainfall via higher FR than larger trees, (2) the FR variability of F. grandifolia induced by the species' ease of generating stemflow under many storm conditions, and (3) the necessity of many years of hydrometeorological sampling to capture long-term rainfall characteristics and trends. The efficiency of smaller trees to preferentially funnel water to their tree base has implications for forests undergoing change. Forest disturbance and subsequent regrowth is dominated by smaller trees, but additional research is necessary to understand how saplings compete among one another to gain access to stemflow and how this may be influenced by changing climates and forest composition.