Rhizophora Apiculata Bl Research Articles

Study of Biomass in Two Mangrove Ecosystems

This study aims to determine the storage of biomass in the mangrove ecosystem of Jakarta Bay compared to Ambon Bay. This research used descriptive quantitative method. Sampling technique using the Point Center Quarter Method (PCQM) which was measured around the chest height of mangrove trees (DBH). Data analysis was performed using an allometric equation where each mangrove plant has a specific gravity. The results of this study indicated that the composition of mangrove species in Ambon Bay consists of 6 mangrove species, namely: Bruguiera cylindrica (L.) Bl, Rhizophora apiculata Bl, Sonneratia alba Smith, Aegiceras corniculatum (L.) Blanco, Avicennia officinalis L, Ceriops tagal. In the ecosystem, Rhizophora apiculata Bl and Sonneratia alba Smith had higher biomass values compared to the other four species. Meanwhile, in Jakarta Bay, the composition of mangrove plants is dominated by Sonneratia alba Smith. The subsurface biomass in the Jakarta Bay and Ambon region is lower than the aboveground biomass.

Distribution of mangroves with different aerial root morphologies at accretion and erosion sites in Ca Mau Province, Vietnam

Aerial roots are a vital feature that allow mangroves to survive in anaerobic and unstable soil conditions. Mangrove species have different aerial root characteristics and show their own site-specific distribution. The distribution of three types of aerial roots with different morphological characteristics was investigated between accretion and erosion sites in Ca Mau, Vietnam. Stilt roots, pneumatophores and knee roots were the three main aerial root types in the study area. Stilt roots of Rhizophora apiculata BL. and pneumatophores of Avicennia species were the two most abundant root types at the study sites, dominating erosion and accretion sites, respectively. Stilt roots had a higher number of primary roots in seaward plots than in landward plots (p < 0.05), supporting the ability of R. apiculata to withstand erosion of the surface. Tidal erosion moved away sediment and exposed roots, which resulted in higher aboveground stilt root height in seaward plots than in landward plots at erosion sites (p < 0.05). The higher density and biomass of pneumatophores in seaward plots than those in landward plots at accretion sites (p < 0.05) confirmed the adaptation of Avicennia to newly accreted sites where tidal inundation and anaerobic conditions limited mangrove growth. The density of A. alba decreased with the distance from the sea at both erosion and accretion sites, implying that this species was a pioneer species adapted to newly accreted sites or disturbed sites among mangrove species. Bruguiera parviflora with knee roots was distributed in more stable conditions. Mangrove species with different root types displayed a zonal distribution with increasing distance from the shoreline. This distribution reflects mangrove species adaptabilities and species-specific roles in the context of coastal processes and site conditions, which should be considered in coastal mangrove restoration.

Effect of fixator on color performance of bark extract from three tropical wetland species for fabric dye

Fixation is a stage in dyeing fabric or batik fabric with natural dyes to obtain the desired color and bind the color so that it does not fade quickly due to sweat, washing, sunray, and rubbing. Three fixators used as color binders were alum (Al2[SO4]3), lime (CaCO3), and tunjung (FeSO4). Each material showed a different color on each extract. This activity aimed to observe the color performance of bark extracts from three wetland species applied to batik fabric with 1 or 2 combinations of fixators. The results showed the color performance of batik fabric depended on the bark of tree species and the kind of fixator. The performance of bark extract with fixators produced darker and sharper colors than without the use of fixators. The application of lime on Rhizophora apiculata Bl. bark extract produced dark moderate orange color, while the combination of lime and tunjung produced very dark orange (Brown tone). The combination of lime and tunjung on Acacia mangium Willd and the Terminalia catappa L. barks gave a dark moderate orange color with different intensities. In contrast, the combination of alum and tunjung on Terminalia catappa L. bark extract produced a very dark greyish orange color.

Short Communication: Structure and composition of mangrove vegetation in Lembar bay area, West Lombok District, Indonesia

Abstract. Sukuryadi, Harahab N, Primyastanto M, Hadi AP. 2021. Short Communication: Structure and composition of mangrove vegetation in Lembar bay area, West Lombok District, Indonesia. Biodiversitas 22: 5585-5592. One of the potential natural resources of coastal areas in West Lombok District, West Nusa Tenggara Province, Indonesia is the 501.9-ha mangrove ecosystem. The purpose of this study was to analyze the structure and composition of mangroves in the Lembar bay area. The study used field observation methods based on predetermined plots. The results showed that the composition of mangroves in the Lembar Bay area consisted of Avicennia alba Bl, Avicennia marina (Forsk) Vierh, Bruguiera cylindrica (L) Bl, Ceriop decandra (Griff) Ding Hou, Ceriop tagal (Perr) C.B. Rob, Lumnitzera littorea (Jack) Voight, Lumnitzera racemosa Willd. Var, Phemphis acidula, Rhizhopora stylosa Griff, Rhizophora apiculata Bl, Rhizophora mucronata Lmk, and Sonneratia alba J.E. Smith. The mangrove vegetation at tree level was composed of 12 species dominated by Rhizhopora stylosa Griff and Rhizophora mucronata Lmk, with Importance Value Index (IVI) of 56.05 and 48.89, respectively, at sapling level 9 species dominated by Rhizhopora stylosa Griff, Bruguiera cylindrica, and Rhizophora mucronata, with IVI of 47.46, 33.33, and 31.07 respectively, and at the seedling level 7 species dominated by Rhizhopora stylosa Griff and Rhizophora mucronata Lmk, with IVI of 47.71 and 37.76, respectively.

Growth analysis of mangrove (Rhizophora apiculata bl) propagule toward differences in types of water and planting media at Makassar mangrove center

Mangrove cultivation is currently hard to find due to many aspects that needed to be observed. The success of mangrove to grow and develop from seeds, nursery, and planting are depending on water salinity and mangroves planting media. The objectives of this study were to investigate the planting media, water types, as well as the combination of planting media and water used, which were the best for mangrove’s growth. The method used in this study was an experimental field approach with a Complete Randomized Design (SRD) factorial experiment and Duncan’s Multiple Range Test as its posthoc test. The growing media used were mud and mud added with compost in a ratio 1:1, and the water types used for watering were seawater, freshwater, and the mixture of seawater and fresh water in a ratio 1:1. The observation variables in this study included the increase of propagule height (measurement from cotyledon’s neck up to the tips of plant shoots), an increase in diameter, and percentages of growing propagules. Watering with freshwater showed the most significant increase in height and diameter of propagules. Meanwhile, for planting media, the most appropriate one was mud added with compost. For treatment combinations, the combination of freshwater with mud added with compost provided a better effect on propagule growth. However, all of the combinations had shown growth.

Quantifying organic carbon storage and sources in sediments of Dong Rui mangrove forests, Tien Yen district, Quang Ninh province using carbon stable isotope

Quantifying organic carbon storage and sources in sediments of Dong Rui mangrove forests, Tien Yen district, Quang Ninh province using carbon stable isotope

Geoinformatics in mangrove monitoring: damage and recovery after the 2004 Indian Ocean tsunami in Phang Nga, Thailand

Abstract. In the aftermath of the 2004 Indian Ocean Tsunami, it has been proven that mangrove ecosystems provide protection against coastal disasters by acting as bioshields. Satellite data have been effectively used to detect, assess, and monitor the changes in mangroves during the pre- and post- tsunami periods. However, not much information regarding mangrove restoration or reforestation is available. Rather than undertaking time-consuming fieldwork, this study proposed using geoinformatic technologies such as Remote Sensing (RS), Geographic Information System (GIS), and Global Positioning System (GPS) to monitor the mangrove recovery. The analysis focused only on the tsunami-impacted mangrove areas along the western coast of the Tai Muang, Takuapa and Khuraburi Districts of Phang Nga Province, southern region of Thailand. The results consisted of 2 parts, first: the supervised classification of main land uses, namely forest, mangrove, agricultural land, built-up area, bare soil, water body, and miscellaneous covers in ASTER images, was conducted using the maximum likelihood method with higher than 75 % for overall accuracy. Once the confusion between classes was improved in post-processing, the accuracy of mangrove class was greater than 85 % for all dates. The results showed that the mangrove area in 2005 was reduced by approximately 5 % (1054.5 ha) from 2003 due to the impact of the 2004 Indian Ocean Tsunami. Although the recovery program (replacing the same species of dead mangrove trees, mainly the Rhizophora apiculata Bl and Rhizophora mucronata Poir, in situ) had started by mid-2005, the areas gradually decreased to approximately 7–8 % in 2006 and 2010 compared with the reference year of 2003. Second, the recovery trend was observed in the Normalized Difference Vegetation Index (NDVI) fluctuation curve and the supporting field survey data. The recovery patterns were summarized into 2 categories: (i) gradually recovery, and (ii) fluctuating recovery. The gradually recovery category that implied the homogeneous pattern or uniform reforestation was observed in the seriously damaged area where most of the mangrove trees were swept away during the tsunami. This pattern covered approximately 50.35 % of the total reforested area. The NDVI time series of the uniform or homogeneous reforested mangrove at the sampled plots has gradually increased after 2005. The fluctuating recovery category that implied the heterogeneous pattern or non-uniform reforestation was observed in partially damaged areas where some of the mangrove trees were swept away and broken but still some trees were remained in the area. The heterogeneous patterns covered approximately 49.65 % of the total reforested area.

Modelling growth and primary production of the marine mangrove ( Rhizophora apiculata BL): A dynamic approach

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.

Determination of soil-related factors controlling initial mangrove (Rhizophora apiculata BL.) growth in an abandoned shrimp pond

To elucidate factors contributing to plant growth in a mangrove plantation, the height of mangrove trees (Rhizophora apiculata BL.) was measured in addition to relative ground level and soil properties in an abandoned shrimp pond in Thailand. Tree height was measured at 1,853 points in the 25 ha experimental site. Soil was sampled from 74 points and physical (hardness, water content) and chemical (e.g. total C and N) properties were determined. The mean tree height of 58.3 cm was relatively small for 2-year-old trees, and varied considerably with a coefficient of variation of 32.4%. The relatively low total C content of the soil, 0.68 × 10−2 kg kg−1, indicated a decline in organic matter content during the conversion from mangrove into shrimp pond. The negative correlation of tree height with relative ground level (P < 0.01) suggested that better growth was observed at a lower area. The important role of soil properties in determining tree height was demonstrated. By combining geostatistics with multivariate analysis, as much as 90% of the spatially structured or non-random variation of tree height was explained by taking into account soil properties in addition to topography. Together, the results suggest that site-specific management, such as site-specific organic matter application, is a feasible and effective option for mangrove rehabilitation.

Antihyperglycemic activity of Rhizophora apiculata Bl. in rats

The article reveals the antihyperglycemic activity of the ethanolic extract of the roots of the Rhizophora apiculata in rats (GLM and STZ models). On further fractionation of the ethanolic extract into four fractions, the activity was localized in the chloroform and aqueous fractions. These on purification led to the isolation of 7 pure compounds – lupeol (1), oleanolic acid (2), β-sitosterol (3), palmitic acid (4), β-sitosterol-β-D-glucoside (5), inositol (6), and pinitol (7). The inositol and pinitol, two of the pure compounds, showed promising activity in STZ model at 100 mg kg−1 dose level.

空撮画像とＧＰＳ比高データによるマングローブ（フタバナヒルギ：Ｒｈｉｚｏｐｈｏｒａ ａｐｉｃｕｌａｔａ Ｂｌ．）に適した生育条件の推定

Mangrove forest was once cut down on a large scale area to use for shrimp culture etc. But now, mangrove reforestation is advanced for the disaster prevention in the coastal area and for increase in production of marine resources. However, reforestation activities are not so going well. Although it is known that the ground level has affected the result of reforestation, the range of exact adaptation is not examined well. When a mangrove area is used for other purposes, the ground level is usually changed. In this paper, in order to estimate the suitable growth condition in Rhizophora apiculata, the relative height in the study area was measured by high precision GPS. Then, the biomass in the area as the index of productivity was calculated using the aerial-photograph taken by radiocontrolled helicopter. Fine satellite imagery is hard to be obtained in a tropical region, and the tidal level at the observation influences analysis for mangrove region. The radio controlled-helicopter can be applied at any time standing by. This is the reason why we used this platform. As a result of the analyzing optimum growth condition in Rhizophora apiculata based on the above-mentioned, it was found that the range of relative height suitable for growing is between 36cm and 95cm.

Changes in polyamine contents and arginine decarboxylase activity associated with elongation growth of hypocotyls inRhizophora apiculataBl.

Changes in polyamine (putrescine, spermidine, spermine) contents and arginine decarboxylase activity in three different regions of developing hypocotyls of Rhizophora apiculata Bl. were analyzed. Among the three polyamines, spermidine was present in higher quantities than either putrescine or spermine. Spermine occurred in the lowest quantities. Spermidine declined rapidly with the age of the hypocotyl. In contrast, a marked increase in putrescine was observed with the age of the hypocotyl. Arginine decarboxylase activity increased during the various developmental stages of hypocotyl growth, particularly in the final stage. The results suggest that putrescine plays a major role in the growth of the hypocotyl as evidenced by simultaneous increase in the content of putrescine and arginine decarboxylase activity.Key words: arginine decarboxylase, elongation, hypocotyls, polyamines, Rhizophora apiculata.

Soil redox conditions and plant–soil relationships in a micronesian mangrove forest

We examined characteristics of the soil environment related to redox in the rhizospheres of three mangrove species that commonly grow in similar hydrogeomorphic settings: Rhizophora apiculata BL, Bruguiera gymnorrhiza (L.) Lamk., and Sonneratia alba J. Redox potential (Eh) values and extractable P concentrations were significantly higher, whereas soluble reactive P (SRP) concentrations were significantly lower in Bruguiera plots than in either Rhizophora or Sonneratia plots. Correlations among Eh, SRP, pyrite and extractable P were significant only at plots with negative Eh values. Sonneratia and Bruguiera plots had significantly different soil redox conditions. Bruguiera plots were characterized by more oxidized soil conditions (ca. 80 mV), lower dissolved P concentrations in porewater (ca. 50%), and higher extractable P concentrations in soil (ca. 25%). Differences in Eh and P reflect real differences among species and appeared not to be associated with hydrology. Species-specific differences may be engendered by the trees themselves, or they may reflect microsite differences that have favored the germination, growth, and survival of particular mangrove species.

Organic Matter Dynamics on the Forest Floor of a Micronesian Mangrove Forest: An Investigation of Species Composition Shifts1

ABSTRACTSpecies composition shifts in mangrove forests may alter organic matter dynamics. The purpose of this study was to predict the effect of species replacements among mangrove trees on organic matter dynamics in a mangrove forest on the island of Kosrae, Federated States of Micronesia. We were particularly interested in elements of the carbon cycle that affect peat accumulation rates, organic matter exports to the estuary and coral reef systems, and soil microbiology. We compared organic matter production and decomposition rates among three mangrove species that commonly grow in similar hydrogeomorphic settings: Rhizophora apiculata BL, which is selectively harvested; Bruguiera gymnorrhiza, which may gradually replace Rhizophora; and Sonneratia alba, which is producing few mature fruits. Sonneratia had significantly higher rates of root production (estimated with ingrowth chambers) than Bruguiera or Rhizophora. Sonneratia foliage had significantly faster decomposition rates and significantly lower lignin:nitrogen ratios than Bruguiera foliage. Live root mass was positively correlated with ingrowth and soil carbon, although soil carbon and ingrowth were not significantly correlated with each other. Humic acid concentrations were significantly higher in Sonneratia rhizospheres than in either Bruguiera or Rhizophora rhizospheres and were positively correlated with root ingrowth. The species changes taking place on Kosrae are likely to result in lower rates of root production and foliage decomposition, and more refractory carbon pools in soil.

Organic Matter Dynamics on the Forest Floor of a Micronesian Mangrove Forest: An Investigation of Species Composition Shifts1

Species composition shifts in mangrove forests may alter organic matter dynamics. The purpose of this study was to predict the effect of species replacements among mangrove trees on organic matter dynamics in a mangrove forest on the island of Kosrae, Federated States of Micronesia. We were particularly interested in elements of the carbon cycle that affect peat accumulation rates, organic matter exports to the estuary and coral reef systems, and soil microbiology. We compared organic matter production and decomposition rates among three mangrove species that commonly grow in similar hydrogeomorphic settings: Rhizophora apiculata BL, which is selectively harvested; Bruguiera gymnorrhiza, which may gradually replace Rhizophora; and Sonneratia alba, which is producing few mature fruits. Sonneratia had significantly higher rates of root production (estimated with ingrowth chambers) than Bruguiera or Rhizophora. Sonneratia foliage had significantly faster decomposition rates and significantly lower lignin:nitrogen ratios than Bruguiera foliage. Live root mass was positively correlated with ingrowth and soil carbon, although soil carbon and ingrowth were not significantly correlated with each other. Humic acid concentrations were significantly higher in Sonneratia rhizospheres than in either Bruguiera or Rhizophora rhizospheres and were positively correlated with root ingrowth. The species changes taking place on Kosrae are likely to result in lower rates of root production and foliage decomposition, and more refractory carbon pools in soil.

Maximum Longevities of Rhizophora apiculata and R. mucronata Propagules

Maximum Longevities of Rhizophora apiculata and R. mucronata Propagules1 Judy Z. Drexler Abstract The longevity of viviparous mangrove seedlings (propagules) in seawater is a key factor determining their ability to survive dispersal both locally and across large expanses of ocean. The purpose of this experiment was to determine the maximum longevities of propagules from two common Pacific mangrove species: Rhizophora mucronata Lamk. and Rhizophora apiculata Bl. Propagules from each of these species were placed in outdoor tubs with continuously flowing seawater. The condition of each propagule was monitored until it sank or started to rot. Propagules were then planted to determine viability. After planting, 50% of R. apiculata propagules and 21% of R. mucronata propagules were viable. For both species, mortality of propagules was strongly related to the length of the floating interval. Maximum longevities for R. mucronata and R. apiculata propagules were 150 (median = 70) and 89 days (median = 7), respectively. Rhizophora mucronata propagules appeared to be better equipped for long-distance dispersal, yet had low survivorship that would decrease overall dispersal opportunities. In comparison, R. apiculata propagules had higher survivorship yet shorter longevity and, thus, appeared to be better equipped for shorter distance dispersal. Several Species of mangroves produce viviparous seedlings (propagules) that are buoyant and can disperse in seawater. The limits for such dispersal have long been the topic of speculation, especially among those seeking to explain the presence of closely related species in distant areas or the total absence of mangroves from suitable habitats (Guppy 1906, Ridley 1930, Tomlinson 1986, Duke 1992). One of the chief factors controlling the dispersal of viviparous mangroves is longevity, the number of days propagules remain buoyant and viable in seawater. Longevity of mangrove propagules varies between different species. Rhizophora mangle propagules can remain viable in laboratory vessels for over 12 months (Davis 1940) and can float throughout a 3-month period (Ellison 1996). Rhizophora harrisonii (now referred to as R. racemosa [pers. comm., N. Duke, Department of Botany, University of Queensland, St. Lucia, Australia]) and Pelliciera rhizophorae propagules are capable of regaining buoyancy after an initial sinking stage and can survive 3 months floating in seawater with no mortality (Rabinowitz 1978). Avicennia marina propagules may remain viable, either exposed by tides or totally submerged (in enclosures in the field), for up to 5 months during enforced dispersal (Clarke 1993). None of these studies, however, sought to determine the maximum longevities of propagules, which are essential for assessing long-distance dispersal capability. The aim of this experiment was to determine maximum longevities of propagules from two common Pacific mangrove species, Rhizophora mucronata Lamk. and Rhizophora apiculata Bl. Longevities of both species were [End Page 17] then used to compare their long-distance dispersal capabilities. Materials and Methods The island of Kosrae, Federated States of Micronesia (5° N, 163° E) was chosen for propagule collection because of the large, productive, and intact stands of both species that grow interspersed in mangrove forests in that location (Ewel et al. 1998). On 6-7 October 1997, mature R. apiculata and R. mucronata propagules were collected from trees within riverine populations on the northern and western parts of the island. Kosrae is a high volcanic island approximately 112 km2 in size that contains 1562 ha of mangroves represented by seven species (Whitesell et al. 1986). The watersheds sampled are relatively pristine, with only minimal impact from agricultural activities and logging. Average air temperature on Kosrae is approximately 27.4°C (Mueller-Dombois and Fosberg 1998), seawater temperature is approximately 28-30°C, and salinity outside the fringing reef is between 33.6 and 34.5 ppt (unpubl. data). After collection, propagules damaged from boring insects were discarded, so that maximum propagule longevities could be determined without confounding effects from herbivory. In total, 82 R. apiculata and 104 R. mucronata propagules were wrapped in moist newspaper, sealed in plastic bags, placed in sturdy cardboard boxes, and shipped overnight to Honolulu, Hawai'i, by air (this method has been used frequently for transporting mangrove propagules [pers. comm., Edward Proffitt, U.S. Geological Survey, National Wetlands Research Center, Lafayette, Louisiana]). On 8 October, each propagule was weighed, measured, and labeled. On the following day propagules were taken...

Life history of Aulacaspis marina Takagi and Williams(Hom., Coccoidea), a new pest of mangrove plantations in Indonesia, and its damage to mangrove seedlings

Scale insects of a newly described species, Aulacaspis marina Takagi and Williams, have killed a large number of mangrove (Rhizophora mucronata Lamk.) saplings planted in abandoned shrimp ponds on Bali island, Indonesia. The mean fecundity of A. marina was 141 eggs. The generation time of this species was between 34 and 42 days, based on four generations, suggesting that the species has nine to 10 generations a year on Bali island where the temperatures are seasonally constant. When crawlers of A. marina were transferred to potted seedlings of R. mucronata, they settled on all leaves of the seedlings. Newly expanded leaves were not infested by the first generation crawlers but were attacked by the following generations. The insect attack induced browning of the leaves and finally caused leaf fall; the leaves fell 25–159 days after the crawler transfer. Consequently, the seedlings died on average 128 (range 82–159) days after infestation. This suggests that once a large number of crawlers attack R. mucronata seedlings, A. marina can kill them within several months. When crawlers were transferred to potted seedlings of three mangrove species (R. mucronata, Rhizophora apiculata Bl. and Bruguiera gymnorrhiza L.), which were the main species planted at the study site, the numbers that developed into adult females did not differ significantly among these species. This suggests that these mangrove species are almost equally susceptible to A. marina.

Foliar fungal endophytes from two species of the mangrove Rhizophora

Endophytic fungi were isolated from leaves of Rhizophora apiculata Bl. and Rhizophora mucronata Lamk., two typical mangrove plants growing in the Pichavaram mangrove of Tamil Nadu, Southern India. Three hundred leaf segments from each plant species were sampled during dry and rainy months. More endophytes could be isolated during the rainy months than during the dry period. Hyphomycetes and sterile forms were more prevalent than ascomycetes or coelomycetes. Sporormiella minima, Acremonium sp. strain MG1 and a sterile fungus (MG90) were isolated from both plants irrespective of the season. Some endophytes were common to both plants, although a few appeared to be host specific. This is the first report on fungal endophytes in leaves of mangrove plants in India.Key words: endophytic fungi, Rhizophora apiculata, Rhizophora mucronata, mangrove, leaves.

Microtopography, soil hardness and survival of mangrove ( Rhizophora apiculata BL.) seedlings planted in an abandoned tin-mining area

In a mangrove area formerly used for tin-mining, the survival and the growth rate of planted Rhizophora apiculata BL. seedlings were studied in relation to land elevation and soil hardness. The growth and survival rates of seedlings were measured at 1-, 3- and 4-year-old stages. The land elevation, soil hardness and soil particle size were also measured in the plot. The survival rate of the seedlings decreased in the first 3 years to 54.9%, and fell to 53.2% in the fourth year. Although the total difference in elevation within the study plot was only 35 cm, both the survival rate and the growth rate were less at higher elevations and in harder soils. The uneven microtopography and the altered soil particle distribution following tin-mining affected the reforestation process.

Structure and Productivity of a 20-Year-Old Stand of Rhizophora apiculata Bl. Mangrove Forest

Mangroves are dominant interface ecosystems be- tween the land and the sea in the tropics, and are of import- ance in the economy of many of these regions in terms of mangrove-linked fisheries and forestry. Recently, mangroves have been of particular interest in relation to global change both because of the possible high carbon sequestration as well as being in the 'forefront' of any sea-level change, because of their location. To understand the impact of global change on these ecosystems (considered terrestrial and aquatic at the same time) and vice versa, it is necessary to obtain 'a more comprehensive and realistic picture of the terrestrial carbon cycle', which is one of the aims of the GCTE Programme. We therefore present here some of the results of our long-term study (started in the mid-1970s) on the carbon and nutrient budget of a mangrove ecosystem as a basis for further studies, including the proposed large-scale biogeochemical transects and climate models proposed by GCTE. The tree density of the 20 m X 40 m plot in the 20-year-old stand was equivalent to 2425 stems per hectare (1975 live trees per hectare). Size (girth at breast height) of Rhizophora apiculata trees ranged from 9 to 75.5 cm with a mean at 39 cm. The smallest live tree weighed 10 kg and the biggest weighed 510 kg with a mean biomass of 122 kg. About 70% of the trees were below 100 kg but the 30% of the bigger trees contributed to slightly more than half of the total biomass of the plot. The canopy had an average height of 21 m. The total standing biomass was 114 t C ha- 1; 74% of the biomass was