TL;DR: In this article, the authors present a review of current knowledge of the effect of forest type, ground cover and climate on rainfall partitioning into throughfall, stemflow and interception.
TL;DR: A reliable estimate of throughfall nutrient flux demands a good forest hydrological budget because the transport of nutrients contained in throughfall and stemflow depends on the magnitude, timing, and form of the precipitation.
Abstract: Publisher Summary This chapter discusses a number of factors influencing the throughfall and stemflow quality and their variation. The effect of the canopy in altering the precipitation quality is also discussed. The annual nutrient return to the forest soil for the elements K, Na, and S is predominantly via throughfall and stemflow and little because of litterfall. Stemflow transfers only 5–20% of the total in precipitation-borne solutes, yet it is the major nutrient input to restricted areas of the forest floor. Because throughfall and stemflow are associated with precipitation events, the transport of nutrients contained in throughfall and stemflow depends on the magnitude, timing, and form of the precipitation. Thus, a reliable estimate of throughfall nutrient flux demands a good forest hydrological budget. The quantity and distribution of throughfall and stemflow depends on microscale features of canopy structure, such as crown density, closeness of the foliar elements, distance from the nearest bole, or open spaces in the canopy.
TL;DR: In this paper, the authors describe the occurrence of high concentrations of ammonium in canopy throughfall and stemflow in woodland areas in the Netherlands, resulting in acid inputs to soils two to five times higher than those previously described for acid atmospheric deposition.
Abstract: Acid rain commonly has high concentrations of dissolved SO2−4, NH+4 and NO−3. Sulphuric and nitric acids are usually considered to be the acidic components, whereas ammonium has a tendency to increase the pH of rainwater1. Ammonium can be transformed to nitric acid in soil but this source of acidity is generally less important than wet and dry deposition of free acids2,3. Here we describe the occurrence of high concentrations of ammonium in canopy throughfall (rainwater falling through the tree canopy) and stemflow in woodland areas in the Netherlands, resulting in acid inputs to soils two to five times higher than those previously described for acid atmospheric deposition2–5. The ammonium is present as ammonium sulphate, which probably forms by interaction of ammonia (volatilized from manure) with sulphur dioxide (from fossil fuels), on the surfaces of vegetation. After leaching by rainwater the ammonium sulphate reaching the soil oxidizes rapidly to nitric and sulphuric acid, producing extremely low pH values (2.8–3.5) and high concentrations of dissolved aluminium in the non-calcareous soils studied. Deposition of ammonium sulphate on the surfaces of vegetation and its environmental consequences are probably most important in areas with intensive animal husbandry.
TL;DR: In this article, a review of the current understanding of stemflow is presented, identifying gaps in the current knowledge of stem flow and stimulating further research in areas where present knowledge is weak.
TL;DR: In this article, the spatial variability of throughfall and stemflow in Amazonian tropical rainforest is analyzed and statistical tests are used to assess the minimum sampling size and number of gauges required.