The self-thinning process in mangrove Kandelia obovata stands

Abstract

The self-thinning process was monitored in crowded Kandelia obovata Sheue, Liu & Yong stands over four years. The frequency distribution of tree phytomass was an L-shape, which was kept over the experimental period. Spearman's rank correlation coefficient for phytomass decreased as the time span of the comparison became longer, a result which indicates that the rank of phytomass changes as stands grow. Death of trees resulted from one-sided competition, i.e., death occurred in lower-rank trees. Surviving trees continued to grow. Whatever the current spatial distribution of the trees, death occurred randomly and the spatial distribution gradually became close to random as stands grew. The self-thinning exponent was 1.46, which can be regarded as evidence in favor of the 3/2 power law of self-thinning. Relative growth rate, RGR, decreased in proportion to decreasing relative mortality rate, RMR, with a proportionality constant of 1.57, which was not significantly different from the slope of the self-thinning exponent. This experimental result probably justifies the assumption that the ratio of RGR to RMR in the mean phytomass-density trajectory for any self-thinning population with different densities becomes constant as the growth stage progresses.

High mangrove density enhances surface accretion, surface elevation change, and tree survival in coastal areas susceptible to sea-level rise

“…However, there were no significant differences in the various measures of individual tree growth among treatments over the course of study. Since self-thinning in crowded mangroves (Analuddin et al 2009) and density-dependent mangrove mortality (Proffitt and Devlin 2005) have been documented as long-term processes in mangroves, a reduction in survival and growth can eventually be expected. There was certainly no evidence for competitive effects after 1,171 days of growth; instead, the absence of any differences in growth and the widening gap in survival rates suggests the continued importance of facilitation at these early stages of stand development.…”

“…For example, Analuddin et al (2009) described self-thinning in crowded mangrove stands of Kandelia obovata, a process widely described in forestry literature. High density conditions can also enhance growth thereby leading to self-thinning at a much faster rate than less dense plantations; this may be particularly true for plants growing in stressed environments (Callaway and Walker 1997;Kirui et al 2008).…”

Self-thinning exponents for partial organs in overcrowded mangrove Bruguiera gymnorrhiza stands on Okinawa Island, Japan

“…Self-thinning studies have tended to focus on terrestrial plant populations (e.g., Harper, 1977;Silvertown and Charlesworth, 2001;Coomes and Allen, 2007;McCarthy and Weetman, 2007;Zhang et al, 2007), though simulation models of self-thinning in mangroves have been developed Hildenbrandt, 2000, 2003;Berger et al, 2002Berger et al, , 2004. In contrast, little has been learned about self-thinning in mangroves from mathematical models (Analuddin et al, 2009;Deshar et al, 2012b), and there is no information on self-thinning in individuals organs (stem, branch, and leaf) in B. gymnorrhiza (Deshar et al, 2012a).…”

Crown shape dynamics of dense mangrove Kandelia obovata stands in Manko Wetland, Okinawa Island, Japan

“…Recently, it was split into two species, one of which is K. candel and the other is K. obovata distributed in China and Japan (Sheue et al 200). Tree density of Kandelia obovata stands decreased year by year, which ranges from 2.68 to 4.88 (ind./m 2 ) in 2004, and decreased from 1.58 to 3.28 (ind./m 2 ) in 2008 (Analuddin et al 2009b). Kandelia obovata is the dominant species in the study site.…”

“…Kandelia abovata is one of among the most dominant mangroves in Okinawa Island, Japan. Although intensive studies have been done in this mangrove K. obovata forest including allometric model and mangrove productivity (Khan et al 2004(Khan et al , 2005(Khan et al , 2007, mangrove photosynthesis capacity (Suwa et al 2006 and mangrove self-thinning (Analuddin et al 2009b) and foliage dynamics (Analuddin et al 2009a), butthe information about how the spatial and temporal maintenances of tree crown shape in dense mangrove forest are scarce. In this study, we monitored the crown shape dynamics of the dense K. obovata forest over five years.…”