Stemflow on the woody parts of plants: dependence on rainfall intensity and event profile from laboratory simulations

Abstract

This paper presents the first experimental study of how rainfall intensity and event profile affects stemflow behaviour on the rigid branches and stems of leafless, woody plants. Constant intensity rainfall simulation experiments showed that stemflow fraction rises with intensity. Varying intensity experiments showed that the stemflow fraction and stemflow flux vary with the rainfall event intensity profile and peak intensity. Stemflow fraction tends to be larger when intensity peaks occur early in the rainfall event, and variable intensity events exhibited peak stemflow fluxes >3 times those seen in constant intensity events. Moreover, experiments in which incident drop energy was reduced by a mesh screen suspended above the test plant commonly showed increases of >100% (and exceeding 300% under particular intensity profiles) in stemflow fraction, depth and peak stemflow flux. The results suggest that the development of trickle pathways along woody branches is facilitated by rain of moderate intensity and that splash dislodgement of attached water progressively reduces the adhesion of drops during intense rainfall. Thus, in plants with extensive woody branches, it is not merely rainfall intensity that determines stemflow fraction but the temporal variations in rainfall intensity. This offers a new explanation for increased stemflow production when trees are leafless, than when foliage is present, in terms of the reduced intensity peaks during rain in the dormant season.Data are reported for paired experiments under dry antecedent conditions and wet antecedent conditions. The numbers in the left-hand column identify the seven intensity profiles. See text for details. STEMFLOW ON WOODY PLANTS

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“…Dunkerley [] conducted a laboratory experiment to investigate stemflow production on the woody parts of trees (branches and boles) in relation to rainfall intensity and event profile. He observed that simulated events of variable intensity produced larger peak stemflow fluxes than events with rainfall of constant intensity; moreover, stemflow fractions of P were larger if peak rainfall intensities were greater in the earlier portion of an event.…”

Influence of scattered Acacia trees on soil nutrient levels in arid Tunisia

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