Modelling growth and primary production of the marine mangrove (Rhizophora apiculata BL): A dynamic approach Takashi Asaeda ⁎, Martin Kalibbala Department of Environmental Science and Human Engineering, Graduate School of Science and Engineering, Saitama University, 255 Shimo Okubo, Sakura-ku, Saitama shi, 338-8750, Japan abstract article info Article history: Received 8 October 2007 Received in revised form 8 January 2009 Accepted 13 January 2009 Keywords: Allometry Ecosystems Mangroves Photosynthesis Rhizophora apiculata A mathematical model was developed to simulate the growth dynamics of monospecific stands of the marine mangroves (Rhizophora apiculata), based on physiological and morphological processes. Six variables to describe the tree organs and three morphological variables to illustrate the growth pattern were selected and incorporated in the model. The growth pattern was described by using a series of mathematical relationships. Net tree growth was derived from the combined effect of photosynthesis, respiration, and mortality. Net primary production was allocated to the tree organs based on their allometric ratios. Coefficients reported in literature were used to simulate the life history and demographics of R. apiculata. Initial diameter at breast height (DBH), daily global radiation and mean air temperature are some of the inputs that were used to calculate the biomass and demographic parameters, using daily time steps. The model was capable of simulating the growth dynamics of R. apiculata stands at lower latitudes, with reasonable accuracy (R 2 ≥ 0.80). However, the predictions at higher latitudes exhibited unsatisfactory model fits. This discrepancy in observations at higher latitudes is probably due to other factors like rainfall distribution, soil structure, which were not incorporated in the model structure. © 2009 Published by Elsevier B.V. 1. Introduction Mangroves are one of the most productive and bio-diverse marine ecosystems on the earth (Lugo and Snedaker, 1974; Boto et al.,1984; Putz and Chan, 1986). They generally consist of trees plus shrubs, which flourish in the mangal — plus other plants like creepers, orchids, ferns, etc, that tolerate salt free environment. It has been reported that mangroves comprise of 60 species in 20 genera, belonging to 16 families (Tomlinson,1986). They play a vital role in the sustainability of tropical and subtropical coastal ecosystems; most especially for fisheries sustainability, functioning as breeding grounds for various fish and prawn species, and food source (Ong, 1982; Gong et al., 1991). The contribution of marine mangroves (Rhizophora apiculata BL.) towards the growth and primary production of mangrove ecosystems is remarkable (Ong et al.,1985; Tomlinson,1986). This is due to the fact that R. apiculata colonizes relatively faster, grows quicker and taller than other species (Putz and Chan, 1986). Its viviparous propagules and subsequent cohorts are reported to depict high resilience abilities during and after initial colonization (Clarke and Allaway, 1993; Clarke and Myerscough, 1993). With about 50% of the mangrove global acreage lost in the past century (Valiela et al., 2001), there is un- doubtedly great need to sustainably manage mangrove ecosystems, and one way of approaching this is by using models. In literature, many studies have been documented on mangroves, with over 7000 titles (Snedaker, 1982). Some of them contain allometric relationships for estimating organs biomass of different mangrove species (Day et al., 1987; Clough and Scott, 1989; Silva et al., 1991; Ong et al., 2003; Khan et al., 2005; Smith and Whelan, 2006), with most of them focusing on R. apiculata. But these relationships were developed using trees sampled at a specific age. Thus, they are devoid of depicting the time dependent growth and biomass dynamics, right from inception to the maturation of stands. The ecological analysis of R. apiculata, with the aid of mathematical modelling has been largely neglected, especially by using both structural and time-dynamic approaches. Few attempts have been done, with propositions of mechanistic models (Chen and Twilley, 1998). This study therefore, endeavours to provide a step forward in mangrove ecosystem modelling, based on the fact that time dynamic modelling of plants has great possibilities of evaluating quantitative plant characteristics, by incorporating various kinds of processes (Asaeda et al., 2000a). In the above regard therefore, the main purpose of this study was to develop a time-dynamic model, simulating growth and primary production of R. apiculata stands, most of which are located in lagoon ecosystems. The formulation of the model was based on first order Journal of Experimental Marine Biology and Ecology 371 (2009) 103–111 ⁎ Corresponding author. Tel.: +81 90 3576 2909. E-mail address: asaeda@mail.saitama-u.ac.jp (T. Asaeda). 0022-0981/$ – see front matter © 2009 Published by Elsevier B.V. doi:10.1016/j.jembe.2009.01.009 Contents lists available at ScienceDirect Journal of Experimental Marine Biology and Ecology journal homepage: www.elsevier.com/locate/jembe