Growth pattern in tropical mangrove trees of Bunaken National Park, North Sulawesi, Indonesia

Abstract

Abstract. Djamaluddin R. 2019. Growth pattern in tropical mangrove trees of Bunaken National Park, North Sulawesi, Indonesia. Biodiversitas 20: 1713-1720. Seasonal diameter growth patterns in mangrove are often related to rainfall, temperature and moisture regime. At any localities, specific environmental factors may influence growth rate of individual trees. I asked whether stem growth of tropical mangrove in BNP is constant over a year, and whether stem growth rates are different by sites, species, and trees of the same species. Dendrometer bands were installed on trees from twelve different sites in BNP to measure stem growth rates. Measurements were made at two months intervals from July 1999 to June 2001 and March 2014 to December 2016. Growth rates measured in trees at the twelve sites varied significantly from 0.83 ± 0.27 to 1.71 ± 0.31 mm month-1. Growth rates were higher on Sonneratia alba (1.65 ± 0.69 mm month-1), low on Rhizophora stylosa, Xylocarpus moluccensis, Avicennia marina, Ceriops tagal (0.82 ± 0.16, 0.82 ± 0.18, 0.85 ± 0.18, 0.88 ± 0.28 mm month-1, respectively), and medium on Rhizophora apiculata, Bruguiera parviflora, Bruguiera gymnorrhiza, Rhizophora mucronata (1.19 ± 0.16, 1.22 ± 0.69, 1.25 ± 0.49, 1.31 ± 0.22 mm month-1, respectively). Statistically, growth rates were higher in trees with initial girths more than 50 cm compared to trees with initial girth less than 50 cm on B. gymnorrhiza, C. tagal, and R. mucronata, but these were slower for R. apiculata and S. alba. Between individual trees in six species tested, the differences in diameter growth rate were statistically significant. Growth rates varied among different site conditions, and the effect of soil water salinity on these was significant at higher intertidal sites. Growth rates exhibited seasonal patterns, and these were correlated positively with rainfall and negatively with temperature. The effect of the 2015-2016 El Nino was significant on reduced growth rates.

Habitat segregation and cryptic adaptation of species ofPeriophthalmus(Gobioidei: Gobiidae)

“…Sonneratia alba ); in Bunaken Timur the sand flats and aprons of the back reefs reached the seaward mangrove fringe and in Bunaken Papaboa (Liang beach) the forest colonized the seaward side of coral sand berms (Appendix SI, Supporting Information). In Pulau Mantehage, the basement was more eroded (maximum 15 m above mean sea level: Djamaluddin, ), forming wider intertidal zones (150–1000 m) covered by soft mud deposits, colonized by dense mangrove formations. All the mudskippers collected or observed throughout the study were found within 1–2 m from the water's edge, with few specimens found in burrows, up to 10 m from the water's edge.…”

“…Consistently, Periophthalmus clade F and P . kalolo were found along the east coast of Mantehage Island, where barrier reefs are better developed (Djamaluddin, ; Fig. ) and offer a less extreme environment for larval settlement.…”

“…The annual temperature regime is virtually constant c . 25–26° C (Djamaluddin, ). The complex pattern of surface currents along the coast is influenced by seasonal winds, tidal action and coastal physiography.…”

“…100–200 mm month −1 ) and a complementary rainy season (north‐west monsoon: c . 200–400 mm month −1 ; Djamaluddin, ). The annual temperature regime is virtually constant c .…”

“…A higher abundance of sand indicates a higher energy of the depositional environment, which corresponds to more marine conditions, within the intertidal zone (intertidal grain size gradient; Raffaelli & Hawkins, ): three B S values were defined. Plant community composition and vegetation density typically changes along the intertidal gradient (Djamaluddin, ), with increasing D V at increasing distances from water, in more terrestrial conditions (Polgar & Crosa, ): five levels of D V were defined. D M was calculated for each survey as the mean horizontal distance between the georeferenced waypoints of the sampling pathways and the seaward edge of the mangrove marine fringe, either along the coast or at the mouth of creeks and rivers, along a direction perpendicular to the coastline (assessed using Google Earth; http://www.google.com/earth).…”