title: Soil phosphorus fractionation and phosphorus-use efficiencies of tropical rainforests along altitudinal gradients of Mount Kinabalu, Borneo.
abstract: We studied soil phosphorus (P) fractionation and P-use efficiencies (PUEs) of rainforests along altitudinal gradients (700-3100 m) on two types of parental rocks (sedimentary versus ultrabasic) on Mount Kinabalu, Borneo. Sedimentary rocks were known to contain more quartz (which does not adsorb P) than ultrabasic rocks. The pool (top 30 cm) of total P was always greater on sedimentary (ranging from 34.9 to 72.6 g m-2) than on ultrabasic (9.0-29.2 g m-2) rocks at comparable altitudes. Accordingly, the pools of organic P and labile inorganic P were always greater on sedimentary than on ultrabasic rocks. The pool of primary mineral, calcium P increased upslope from 1.7 to 4.3 g m-2on sedimentary rock, suggesting that the altitudinal sequence of the sites reflected a decreasing magnitude of soil weathering upslope. The pool of calcium P on ultrabasic rock did not vary consistently with altitude (1.2-2.8 g m-2), probably reflecting the greater between-site variability of primary mineral P in parent rocks. When all sites were compared, the pool of most labile, bicarbonate-extracted inorganic P increased (ranging from 0.02 to 1.85 g m-2) with increasing calcium P. Calcium P was therefore considered to be an important P source to the biota on Kinabalu. Gross patterns in the variation of PUE (indexed as the reciprocal of the P concentration in litter) were best explained by the pool size of actively cycling P (total P minus occluded inorganic P). PUE, however, demonstrated distinct altitudinal patterns to generate an intricate conrol of P use pattern by soil P pools and altitude.
authors.affiliation: Japanese Forestry and Forest Products Research Institute, P.O. Box 16, Tsukuba Norin Kenkyu Danchi, Ibaraki 305-8687, Japan e-mail: kanehiro@ffpri.affrc.go.jp Tel.: +81-298-733211, Fax: +81-248-731541, , , , , , JP.
authors.forename: K
authors.initials: K
authors.lastname: Kitayama
authors.affiliation: Forest Research Center, Forestry Department, P.O. Box 1407, 90715 Sandakan, Sabah, Malaysia, , , , , , MY.
authors.forename: N
authors.initials: N
authors.lastname: Majalap-Lee
authors.affiliation: Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060, Japan, , , , , , JP.
authors.forename: S
authors.initials: S
authors.lastname: Aiba
keywords: Key words Ecosystem control; Litterfall; Nutrient-use efficiency; Parent materials; Soil phosphorus fractionation