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Experimental evidence for limited leaching of phosphorus from canopy leaves in a tropical dry forest


Correspondence to: Christiane W. Runyan, Department of Environmental Sciences, University of Virginia, 291 McCormick Road, Box 400123, Charlottesville, VA, 22904-4123 USA.



Apart from being water limited during the dry season, some tropical dry forests are also phosphorus (P) limited. For these systems, throughfall contributes an important source of P. Leaf leaching of P would confound the quantification of external P in throughfall; and thus, it is necessary to determine the importance of leaf leaching for such systems. In this study, we used a modification of the classic methodology to determine whether P is leached from common tree species found in a tropical dry forest. Our modification of washing the leaves allowed us to also examine the amount of organic phosphorus (PO) and inorganic phosphorus (PI) yielded instantaneously from the leaves, representing P deposited on leaf surfaces. We compared leaves from mature and successional forests to understand how canopy structure affects deposition. Although we saw no evidence for leaching, the decline in rinsate P between sample times may suggest that microbes on the surfaces of leaves take up P dissolved in intercepted canopy water. The washing of leaves during the experiment yielded measurable quantities of PO and PI. The quantity of PO or PI yielded from the surfaces of leaves differed between species and forest types. Scaled-up estimates suggested that 0·8 g PI ha−1 per rainfall event and 2·8 g PO ha1 event−1 were yielded from the successional forest and 4·4 and 10·7 g PO ha1 event1 from the mature forest, the latter of which is very similar to measured throughfall values for this area. Copyright © 2012 John Wiley & Sons, Ltd.

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