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# Ecological Studies in Four Contrasting Lowland Rain Forests in Gunung Mulu National Park, Sarawak: II. Litterfall, Litter Standing Crop and Preliminary Observations on Herbivory

John Proctor, J. M. Anderson, S. C. L. Fogden and H. W. Vallack
Journal of Ecology
Vol. 71, No. 1 (Mar., 1983), pp. 261-283
DOI: 10.2307/2259976
Stable URL: http://www.jstor.org/stable/2259976
Page Count: 23
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## Abstract

(1) Small litterfall (leaves, wood ⩾ 2 cm diameter, reproductive parts, and trash) was compared on sites of 1 ha in each of four types of lowland forest in Gunung Mulu National Park, Sarawak, for quantity, seasonal distribution and the concentrations of nitrogen, phosphorus, potassium, sodium, calcium, magnesium and total phenols. The sampling period was 50 weeks for the sites in alluvial forest (AF), dipterocarp forest (DF) and heath forest (HF) and 42 weeks for the forest over limestone site (LF). (2) The total small litterfall was (t ha-1 year-1 ± 95% confidence limits): for the AF, 11.5 ± 1.9; DF, 8.8 ± 0.6; HF, 9.2 ± 1.2; and LF, 12.0 ± 1.3. A peak of litterfall occurred on all four sites during a May-June period of high rainfall before the driest time of the year. (3) The element concentrations in the litterfall differed greatly between each forest type. The concentrations of all elements (except calcium in samples from the LF) were below or within the ranges reported for other tropical forests and there was no consistent seasonal variation. The low calcium concentration in the DF litterfall and low nitrogen in the KF litterfall were notable. (4) Total polyphenol concentrations in the leaf litterfall were ranked HF > LF > DF > AF. (5) Large-wood litterfall was measured over a shorter period than the small litterfall. Virtually no wood over 10 cm diameter fell in the collection quadrats and the results for the $> 2 cm-\leqslant 10$ cm diameter wood were ranked AF > HF > LF > DF. (6) Small-litter standing crop showed some changes with season and differences between the forests. The lowest value was 4.7 t ha-1 in the AF in March 1978, the highest was 7.5 t ha-1 in the LF in February 1978. (7) Large-wood (> 10 cm diameter) standing crop values were (t \mathrm{ha}^{-1} \pm 95% confidence limits): AF, 20.3 ± 17.6; DF, 52.7 ± 27.0; HF, 22.7 ± 16.6; and LF, 52.3 ± 38.1. (8) Levels of herbivory, judged from the proportions of areas of leaves in litterfall eaten by invertebrates, were at least as high as those in other tropical forests in which they have been measured. Leaf hole proportions were ranked AF > HF > DF > LF. (9) There were large differences between the four forests in the annual addition of elements in litterfall and in the element contents of small-litter standing crop and soils. There were several examples of high litterfall content/soil pool quotients. The highest quotient (2.8) was for calcium in the DF, which seems to be an extreme example of rapid cycling of a deficient element in a rain forest.

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