Winter stemflow leaching of nutrient-ions from deciduous canopy trees in relation to meteorological conditions

Leaching of nutrients from aboveground vegetative surfaces of canopy trees represents an important component of the intra-system nutrient cycle in forested ecosystems. The hypothesis tested is that there is no difference in winter stemflow leachate concentration or quantity among different storm types and meteorological conditions. Non-hierarchical cluster analysis demonstrated that there was an association between precipitation event type and chemical enrichment of stemflow drainage from the leafless crowns of deciduous canopy trees monitored over two successive winter seasons. Three clusters were derived on the basis of chemical enrichment. Stemflow was most enriched during snow-to-rain events. Rain and rain-to-snow events also enriched stemflow but to a lesser extent than snow-to-rain events. Snow, sleet, and rain shower events enriched stemflow the least. Stemflow from all precipitation events were chemically enriched compared to the incident bulk precipitation. The extent of chemical enrichment was inversely proportional to stemflow volume generated by canopy trees during discrete precipitation events. Other factors affecting the amount of winter stemflow leaching were precipitation type (influences interception efficiency) and intra-storm temperature regime. Stemflow from precipitation events of long duration and low intensity with air temperature oscillations around the freezing point was the most enriched because of the longer residence time of intercepted precipitation with the leafless crown. Because stemflow leachate quantities were found to differ among precipitation events as a function of meteorological conditions, it is possible that the winter biometeorology of deciduous forests could potentially impact tree vigor, forest stand productivity, and species composition of deciduous forests. (C) 2003 Elsevier Science B.V. All rights reserved.