Litter production, decomposition and nutrient return of uplifted coral reef tropical forest Jiung-Hao Liao a , Hsiang-Hua Wang b , Chen-Chi Tsai c , Zeng-Yei Hseu a, * a Department of Environmental Science and Engineering, National Pingtung University of Science and Technology, 1 Hseuh-Fu Road, Nei-Pu, Pingtung 91201, Taiwan b Division of Forest Biology, Taiwan Forestry Research Institute, Council of Agriculture, Taipei 10014, Taiwan c Department of Natural Resources, National I-Lan University, I-Lan 26015, Taiwan Received 25 March 2006; received in revised form 10 August 2006; accepted 10 August 2006 Abstract Four habitat types in a 10-ha permanent plot of an uplifted coral reef forest in southern Taiwan were chosen and subjected to systematic litterfall related processes. Ebenaceae and Euphorbiaceae were the dominant families. The common species in the four habitats were Diospyros maritime, Ficus benjamina and Melanolepis multiglandulosa. Habitat I on the flat terrace was dominated by Bischofia javanica and Palaquium formosanum; habitat II on the ridge of exposed coral reef was dominated by Aglaia formosana and Pouteria obovata; habitat III on the sedimentary basin was dominated by Macaranga tanariu; habitat IV at the bottom of valley was dominated by Pisonia umbellifera. Litter productions, decomposition processes and nutrient returns were monitored over a 12-month period in the four habitats. Bulk litter was gathered from traps for monthly accession of litterfall. Mixed-species litter bags containing equal portions of the individual species were used to measure the decomposition constants of the leaf litter. Fresh and decomposing litters were analyzed for C, N, P, Ca, Mg, K and Na. Experimental results indicated that mean monthly litterfall in all the habitats displayed a marked seasonal pattern, with spring troughs and summer, autumn and winter peaks associated with the typhoon and monsoon seasons. The annual litterfall ranged from 6.98 to 9.13 Mg ha À1 year À1 , is within but in the higher range for tropical forests. The litterfall production in habitats I and IV was significantly ( p < 0.05) exceeding that in habitats II and III. This phenomenon probably occurs because the dominant tree species of habitat II are relatively adapted to strong wind, and the leaves survived for a long time on the exposed coral reef; meanwhile, habitat III comprised secondary forest which was dominated by early succession tree species with lower leaf area index and basal area than those in other habitats. Significant differences in initial C concentration in the leaf litter were observed in the four habitats. Carbon release from the leaf litter was fastest in habitat IV, while the thin and less rigid leaves without prominent skeletal tissues of Pisonia umbellifera are easily decomposed. The mass and nutrients in the leaf litter could be arranged sequentially in order of decreasing mobility: Ca > Mg = N > Na > K > P > mass > C. Carbon was returned to the forest floor in the highest amount, and the next element was Ca which ranged from 196 to 324 kg ha À1 year À1 . Surprisingly, the annual returns of Ca significantly exceeded those of N, and differed significantly from those of other tropical forests. # 2006 Elsevier B.V. All rights reserved. Keywords: Uplifted coral reef; Litterfall; Litter decomposition; Litter nutrient release; Tropical forest 1. Introduction The Kengting Uplifted Coral Reef Nature Reserve (KUCRNR), located at the southern tip of Taiwan Island, is the only fully ecosystem characterized by evergreen broad- leaved forest on an uplifted coral reef landscape in Taiwan. Ebenaceae and Euphorbiaceae are the dominant plant families in this region, and diverse plant habitats were further developed on the different landscapes (Wang et al., 2004). Taiwan is suited in the northeast trending collision zone of the Eurasian plate and Philippine Sea plate. The active tectonics results in uplifted coral reefs, such as KUCRNR (Ho, 1988). This ecosystem is very unique because of uplifted coral reef landscape and vegetation. However, no systematic study has been conducted of litterfall and decomposition processes in KUCRNR, where is a tropical lowland evergreen broad-leaved rain forest. The litter on the forest floor serves as an input–output system for nutrients, and the rates at which forest litter falls and decays regulate energy flow, primary productivity and nutrient cycling in forest ecosystems (Olson, 1963; Bray and Gorham, 1964). It www.elsevier.com/locate/foreco Forest Ecology and Management 235 (2006) 174–185 * Corresponding author. Tel.: +886 8 7740253; fax: +886 8 7740320. E-mail address: zyhseu@mail.npust.edu.tw (Z.-Y. Hseu). 0378-1127/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.foreco.2006.08.010