Rhizophora Stylosa Griff Research Articles

Analisis Pertumbuhan Bibit Bakau Rhizophora stylosa Griff. di Kawasan Rehabilitasi Mangrove Tanjung Pasir, Tangerang

<strong>Growth Analysis of Rhizophora stylosa Griff. Seedlings in Mangrove Rehabilitation Area of Tanjung Pasir, Tangerang.</strong> Mangrove rehabilitation is urgently needed as an effort to preserve coastal plant ecosystems which are decreasing in Indonesia. It requires the preparation of good seedlings to support the rehabilitation efforts. The seedling of Rhizophora stylosa is suitable for being able to well adapt to the wide range of salinity and illumination. Research on the growth of R. stylosa seedlings was conducted in degraded mangrove areas in the coastal region of Tanjung Pasir, Tangerang, from August to November 2005. This research analyzes the growth patterns R. stylosa seedlings in two habitat types, i.e. the pond dikes and the green belts. A total of 100 seedlings were planted in each habitat with a spacing of 0.5 m. Seedling growth parameters such as the percentage of survival, height and diameter of the stem, and number of leaves were measured monthly. Twoway ANOVA analysis was conducted to determine the overall differences in the parameters between locations and time of observation, as well as its interaction. The results showed the percentage of survival of seedlings planted in the green belts was higher than in the pond dikes (p <0.05), while the growth of the height and diameter of the seedlings planted in the pond dikes was higher than those planted in the green belts. The number of leaves of seedlings planted in both habitats was not significantly different. The regression equation between seedling height (X) and stem diameter (Y) showed a high correlation (p <0.01) in the green belts, which is Y = 0,018X + 0.746 (R = 0.606). A strong correlation was found between stem height (X) and the number of leaves (Y) for the seedlings planted in the pond dikes by the regression equation Y = 0,156X - 2.968 (R = 0.501).<br /><br />

CARBON SEQUESTRATION POTENTIAL IN MANGROVE FORESTS IN HAI PHONG COASTAL AREAS

Mangrove is known as a big carbon sink in coastal areas. It is an important organic carbon source which provides for coastal ecosystems. The assessment of the carbon sequestration potential of mangrove contributes to making a scientific base for mangrove conservation and rehabilitation. In this study, the carbon sequestration of mangrove in the Hai Phong coastal areas was measured at three dominant species of mangrove Rhizophora stylosa Griff; Kandelia obovata Sheue, Liu & Yong and Sonneratia caseolaris (L.) Engl. The result of the assessment was described by the net canopy photosynthesis (PN­), above and below ground biomass (AGB and BGB), and organic carbon content in sediment. The result showed that the PN ranged from 31.94 ± 1.59 tC.ha-1.yr-1 to 34.83 ± 1.95 tC.ha-1.yr-1 with the R. stylosa community being highest. Above and below ground biomass C stock ranged from 4.03 ± 0.31 t.ha-1 to 294.43 ± 24.67 t.ha-1 and from 2.38 ± 0.16 t.ha-1 to 114.16 ± 8.9 t.ha-1, respectively. S. caseolaris community had the highest biomass and R. stylosa community had the lowest biomass. The measurements of C stock in mangrove biomass for three species were R. stylosa (2.69 ± 0.19 t.ha-1); K. obovata (6.72 ± 0.34 t.ha-1) and S. caseolaris (171.61 ± 14.1 t.ha-1). The organic carbon content of sedimentscores at 10 cm depth ranged from 685.63 milligram.kg-1 of se. dry to 2676.64 milligram.kg-1 of se. dry and at 40 cm depth ranged from 937.38 milligram.kg-1 of se. dry to 2557.55 milligram.kg-1 of se. dry. The total organic carbon was stored highest in the R. stylosa community.

Contribution to the structure study of actual situation of plant mangrove communites in Xuan Thuy national park, Nam Dinh province

This paper presented the result of the structural study of the actual plant mangrove forest communites in Xuan Thuy National Park. For the first time, the structure of six plant mangrove communities was analysized, the density of trees, generating stautus and rate were calculated by using standard plot and positioning plot methods. The biomass of the plant mangrove communities in Xuan Thuy national park were tested and calculated based on data from the diameter at breast height method. Results show that community which dominantes by A. corniculata (L.) Blanco, K. candel (L.) Druce, S. caseolaris (L.) Engl. has highest average biomass (about 216.6821 tons/ha), while community dominated by K. candel (L.) Druce, Sonneratia caseolaris (L.) Engl., Aegiceras corniculata (L.) Blanco), Rhizophora stylosa Griff. has lowest average biomass (about 56.5631 tons/ha).

Flora diversity of the Bai Tu Long national park (Quang Ninh province)

The Baitulong national park (BTLNP) in the Quangninh province was established by the decision No. 85/2001 Q§-TTg of the Prime Minister in 2001. Before that, some expeditions to investigate the flora of the BTLNP had been carried out. About 117 families with 337 genera, 494 vascular plant species were recorded in September 2000. Some other investigations have been performed in two years 2005-2006. Preliminary results showed that the flora of the BTLNP is very rich and diversified. A checklist with 780 species belonging to 468 genera of 135 families of 5 vascular plant phyla has been done. Almost of them belonged to the phylum Magnoliophyta (114 families, 438 genera, 729 species). Information of valuable, rare and endangered species had been reported. Among total 18 valuable, rare or endangered species in the park, 10 species was recorded in the Red Data Book (1996), and 10 species existed in the annexes IA or IIA of the Governmental Decree 32/2006/ND/CP (March 2006). There were also 557 useful species in the BTLNP. Among them, 431 species have been used as medicinal plants. Especially, Ilex kaushue S. J. Hu had been found for the first time in the BTLNP. This species and some others such as Morinda officinalis How, Ardisia silvestris Lour needed to be protected, propagated and developed. Besides, 116 species were listed as timber trees (Erythrophleum fordii Oliv., Hopea chinensis (Merr.) Hand.-Mazz., Vatica odorata (Griff.) Symingt., Bruguiera gymnorhiza (L.) Savigny, Rhizophora stylosa Griff.). Statistics showed that other groups of useful plants existed in the BTLNP. Groups of edible fruit and nut plants consist 44 species, vegetable plants 33 species, essential oil and fat plants 27 species, fibred plants 20 species.

A model of seasonal foliage dynamics of the subtropical mangrove species Rhizophora stylosa Griff. growing at the northern limit of its distribution

Progress of forest production in response to the environment requires a quantitative understanding of leaf area development. Therefore, it is necessary to investigate the dynamics of seasonal crown foliage in order to understand the productivity of mangroves, which play an important role in the subtropical and tropical coastlines of the world. Crown foliage dynamics of the mangrove Rhizophora stylosa were studies to reveal patterns of leaf recruitment, survival and seasonal leaf area growth. Flushing of leaves occurred throughout the year, but both flushing and leaf area growth pattern of leaves varied with season. Maximum flushing occurred in summer, but leaf areas did not differ significantly with season. The half-expansion period is longer, and the intrinsic rate of increase was lower in winter. Summer flushed leaves grew faster at their initial stage and reached their maximum area over a shorter period of time. The difference in temperature and air vapor pressure deficit (VPD) between summer and winter contributed to the present dynamics of foliage patterns. The mean leaf longevity was estimated to be 13.1 month. The crown foliage area was almost stable throughout the year. Homeostatic control of the crown foliage area may be accompanied by the existence of ecophysiological mechanisms in R. stylosa. Integrating crown foliage dynamics into forest models represents an important step towards incorporating physiological mechanisms into the models for predicting growth responses to environmental changes and for understanding the complex responses of tree growth and litter production.

Long-term versus daily stem diameter variation in co-occurring mangrove species: Environmental versus ecophysiological drivers

High temporal resolution stem diameter variation (SDV) patterns have been widely recognized as a tool to study fundamental plant physiological mechanisms underlying whole-plant functioning and growth. As an integrative response to hydraulic and carbon related processes, SDV research has greatly improved insights in plant functioning of several herbaceous and woody species. Nevertheless, to date little detailed information on SDV and related physiological processes is available for mangrove species. By measuring continuous tree physiological variables such as stem diameter variations, sap flow and stem water potential in relation to the microclimatic conditions, the water use strategies of two co-occurring mangrove species, Avicennia marina (Forssk.) Vierh. and Rhizophora stylosa Griff. were investigated. Even though both species showed a similar long-term growth trend, closely linked to the environmental conditions, their daily SDV pattern was markedly different. While for Avicennia marina the SDV showed the standard daily pattern of morning decline and evening rise, the opposite daily SDV pattern was observed for Rhizophora stylosa. The contrasting patterns of SDV in both species thriving in the same environment indicates the importance and complexity of physiological endogenous mechanisms in addition to environmental conditions in controlling SDV and radial stem growth.

Antibacterial activity of some mangrove species in Xuan Thuy national park, Nam Dinh, Vietnam

Possessing more than 3,000 km coastal lines, Vietnam has several mangrove forests which are potential sources of natural products with pharmaceutical properties. In order to investigate the applications of mangrove forests in Vietnam, nine mangrove plants including Kandelia obovata, Pluchea pteropoda Hemsl., Aegiceras corniculatum (L.) Blanco, Lumnitzera racemosa Wild., Sonneratia caseolaris (L.) Engl., Sonneratia apetala Buch. Ham, Bruguiera gymnorrhiza (L.) Lam, Rhizophora stylosa Griff. and Avicennia marina (Forsk.) Vierh. were collected in Xuan Thuy National Park, Nam Dinh province, Vietnam. Methanol extracts from barks and leaves of these species were used to evaluate antibacterial activity against 4 control bacteria Escherichia coli ATCC®25922™*; Staphylococcus aureus ATCC®25923™; Proteus mirabilis ATCC®29245™ and Proteus vulgaris ATCC®33420™ via the agar well diffusion method. All of methanol extracts from nine mangrove plant species collected in Xuan Thuy National Park inhibited the growth of tested pathogenic bacterial strains. Lumnitzera racemosa Wild., Sonneratia caseolaris (L.) Engl. and Sonneratia apetala Buch. Ham expressed the highest antibacterial activity. Aegiceras corniculatum (L.) Blanco and Avicennia marina (Forsk.) Vierh showed medium activity. Kandelia obovata, Pluchea pteropoda Hemsl., Rhizophora stylosa Griff. and Bruguiera gymnorrhiza (L.) Lam showed the lowest activity.

Phenological traits of the mangrove Rhizophora stylosa Griff. at the northern limit of its biogeographical distribution

The vegetative and reproductive phenology of the subtropical mangrove species Rhizophora stylosa was investigated at Manko Wetland, Okinawa Island, Japan. We assessed phenology using litterfall data over four years. Leaf and stipule litterfall occurred throughout the year, with distinct seasonal patterns. Kendall’s coefficient of concordance, W, revealed that the monthly changes in leaf and stipule litterfall were strongly and significantly concordant among years. Leaf litterfall was significantly correlated with monthly maximum wind speed and monthly day length, and stipule litterfall was significantly correlated with monthly mean air temperature and relative humidity. Branch litterfall showed no clear monthly pattern and correlated well with monthly maximum wind speed. Mean total litterfall was 11.2 Mg ha−1 year−1, with the largest component being vegetative organs (78.7 %). Flower, fruit, and propagule litterfall were all highest in summer and lowest in winter. The W values revealed that most reproductive organs in litterfall had significant monthly trends. Flower and fruit litterfall were significantly correlated with monthly day length and monthly mean air temperature, respectively. The average development periods from flower buds to flowers, fruits, and mature propagules were approximately 2–3 months, 4–5 months, and 11–12 months, respectively. Except for branches, all vegetative and reproductive components of litterfall had approximately one year cycles.

The anatomical basis of the link between density and mechanical strength in mangrove branches.

Tree branches are important as they support the canopy, which controls photosynthetic carbon gain and determines ecological interactions such as competition with neighbours. Mangrove trees are subject to high wind speeds, strong tidal flows and waves that can damage their branches. The survival and establishment of mangroves partly depend on the structural and mechanical characteristics of their branches. In addition, mangroves are exposed to soils that vary in salinity. Highly saline conditions can increase the tension in the water column, imposing mechanical stresses on the xylem vessels. Here, we investigated how mechanical strength, assessed as the modulus of elasticity (MOE) and the modulus of rupture (MOR), and density relate to the anatomical characteristics of intact mangrove branches from southeast Queensland and whether the mechanical strength of branches varies among mangrove species. Mechanical strength was positively correlated with density of mangrove intact branches. Mechanical strength (MOE) varied among species, with Avicennia marina (Forssk.) Vierh. branches having the highest mechanical strength (2079±176MPa), and Rhizophora stylosa Griff. and Bruguiera gymnorrhiza (L.) Savigny ex Lam. and Poiret having the lowest mechanical strength (536.8±39.2MPa in R. stylosa and 554±58.2MPa in B. gymnorrhiza). High levels of mechanical strength were associated with reductions in xylem vessel lumen area, pith content and bark content, and positively associated with increases in fibre wall thickness. The associations between mechanical strength and anatomical characteristics in mangrove branches suggest trade-offs between mechanical strength and water supply, which are linked to tree growth and survival.

Growth of the mangrove species Rhizophora stylosa Griff. at its southern latitudinal limit in eastern Australia

A study on the growth of Rhizophora stylosa Griff. was undertaken in three estuaries spanning the southernmost 265km of its range at its latitudinal limit in eastern Australia. A shoot tracking methodology was devised to follow vegetative phenological patterns and branching and to derive indices of relative growth between trees. Despite an apparent expansionary phase in distribution and a recent increased trend in mean temperature, comparisons of growth in the three estuaries do not suggest a latitudinal cline. The phenologies of leaf gain and leaf loss are generally comparable between R. stylosa in New South Wales and elsewhere, as is the rate of growth assessed by leaf initiation. However, leaf longevity and the number of leaves held on the shoot appears to be overall greater in NSW than in lower latitudes, perhaps as an adaptive response to lower levels of assimilation. This study suggests that R. stylosa is not close to physiological limits at the end of its range, supporting a contention that its current known southern limit is not at an absolute thermal boundary.

Contrast of nitrogen contents around roots of mangrove plants

Nitrogen is one of the most limiting elements for plant growth. Although nitrogen dynamics in mangrove forests are well understood at the ecosystem level, the nitrogen conditions in the root-zones of plants are less clear. The aim of this study was to analyze in detail the nitrogen conditions in the root zone of mangroves. We conducted a field survey in an area inhabited by three species of mangroves (Avicennia marina (Forsk.) Vierh., Rhizophora stylosa Griff. and Bruguiera gymnorrhiza (L.) Lam.). We collected soil and soil pore-water from the mangrove root zone, in which there were abundant fine roots, and from an area 10-cm away from the root zone (no-root zone). We determined soil organic nitrogen contents and concentrations of ammonium-N, nitrite-N and nitrate-N in soil pore-water along with soil temperature, NaCl and pH. We observed several common characteristics among the three mangrove species; in the root zone, pH was lower, soil organic matter content was higher, soil C:N was lower, and soil pore-water nitrite-N and nitrate-N were higher than their respective values in the no-root zone. These trends were observed in both summer and winter while soil temperature was about 10°C higher in summer than in winter. The fact that C:N was lower in the root zone than in the no-root zone suggests that bacterial nitrogen assimilation occurred near plant roots. The contrast in nitrogen content within a small scale (10 cm) between the root zone and no-root zone suggests that mangroves retain nitrogen source in their root zone. This property clearly works efficiently in intertidal habitats where tidal nitrogen export occurs naturally.

Distribution and stem growth patterns of mangrove species along the Nakara River in Iriomote Island, Southwestern Japan

We examined variations in stand structure and tree growth of a mangrove forest along two gradients: from the river mouth to upper stream and from the riverside to inland, along the Nakara River, Iriomote Island, Japan. Bruguiera gymnorrhiza (L.) Lamk. occurred throughout the intertidal area, though Rhizophora stylosa Griff. and Kandelia candel (L) Druce did not occur upstream. Basal area and maximum tree height of B. gymnorrhiza decreased downstream. The growth rate in stem diameter of B. gymnorrhiza decreased downstream in relation with the soil salinity. The basal area and the maximum tree height of B. gymnorrhiza increased with the distance from the riverside. R. stylosa increased in stem diameter and growth rate toward the riverside.

Critical tidal level for forestation with hypocotyl of Rhizophora stylosa Griff along the Guangxi coast of China

From August 2004 to August 2005, three replicated experimental platforms were constructed in a section of tidal flat in Yingluo Bay of Guangxi to study the growth and physiological responses of Rhizophora stylosa Griff seedlings to the waterlogging stress of tide in diurnal tide zone. A total of eight tidal flat elevation (TFE) treatments, i. e., 320 cm, 330 cm, 340 cm, 350 cm, 360 cm, 370 cm, 380 cm and 390 cm above Yellow Sea Datum (YSD), were created on each platform. The results showed that lower TFEs (320-330 cm YSD) slightly increased the stem height of 1-year old seedlings, while higher TFFs ( > 340 cm YSD) increased the seedlings growth significantly. Moderate TFEs (350-370 cm YSD) favored the development of knots. Leaf number, leaf conservation rate, and leaf area per seedling all decreased dramatically with decreasing TFE. Lower TFEs had a larger damage to Chl a, but Chl b was less affected. The Chl a/b ratio decreased with decreasing TFE. Prolonged waterlogging induced a higher SOD activity in root, while moderate TFE inhibited the SOD activity in leaf. The POD activity in root and leaf increased with decreasing TFE. Waterlogging stress decreased the biomass of individual organs and whole seedling. With increasing waterlogging, the biomass partitioning in 1-year old seedlings increased from leaf to stem. The survival rate decreased sharply from 88.9% to 40.0% as TFE decreased, while more than 80% of the seedlings could survive at the TFE being 370 cm YSD and above. It was proposed that the local mean sea level could be adopted as the critical tidal level for the forestation with hypocotyls of R. stylosa along the Guangxi coast.

Seasonal changes in canopy photosynthesis and foliage respiration in a Rhizophora stylosa stand at the northern limit of its natural distribution

Gross photosynthesis and respiration rates of leaves at different canopy heights in a Rhizophora stylosa Griff. stand were measured monthly over 1 year at Manko Wetland, Okinawa Island, Japan, which is the northern limit of its distribution. The light-saturated net photosynthesis rate for the leaves at the top of the canopy showed a maximum value of 17 μmol CO2 m−2 s−1 in warm season and a minimum value of 6 μmol CO2 m−2 s−1 in cold season. The light-saturated gross photosynthesis and dark respiration rates of the leaves existing at the top of the canopy were 2−7 times and 3–16 times, respectively, those of leaves at the bottom of the canopy throughout the year. The light compensation point of leaves showed maximum and minimum peaks in warm season and cold season, respectively. The annual canopy gross photosynthesis, foliage respiration, and surplus production were estimated as 117, 49, and 68 t CO2 ha−1 year−1, respectively. The energy efficiency of the annual canopy gross photosynthesis was 2.5%. The gross primary production GPP fell near the regression curve of GPP on the product of leaf area index and warmth index, the regression curve which was established for forests in the Western Pacific with humid climates.

Triterpene synthases from the Okinawan mangrove tribe, Rhizophoraceae

Oleanane-type triterpene is one of the most widespread triterpenes found in plants, together with the lupane type, and these two types often occur together in the same plant. Bruguiera gymnorrhiza (L.) Lamk. and Rhizophora stylosa Griff. (Rhizophoraceae) are known to produce both types of triterpenes. Four oxidosqualene cyclase cDNAs were cloned from the leaves of B. gymnorrhiza and R. stylosa by a homology-based PCR method. The ORFs of full-length clones termed BgbAS (2280 bp, coding for 759 amino acids), BgLUS (2286 bp, coding for 761 amino acids), RsM1 (2280 bp, coding for 759 amino acids) and RsM2 (2316 bp coding for 771 amino acids) were ligated into yeast expression plasmid pYES2 under the control of the GAL1 promoter. Expression of BgbAS and BgLUS in GIL77 resulted in the production of beta-amyrin and lupeol, suggesting that these genes encode beta-amyrin and lupeol synthase (LUS), respectively. Furthermore, RsM1 produced germanicol, beta-amyrin, and lupeol in the ratio of 63 : 33 : 4, whereas RsM2 produced taraxerol, beta-amyrin, and lupeol in the proportions 70 : 17 : 13. This result indicates that these are multifunctional triterpene synthases. Phylogenetic analysis and sequence comparisons revealed that BgbAS and RsM1 demonstrated high similarities (78-93%) to beta-amyrin synthases, and were located in the same branch as beta-amyrin synthase. BgLUS formed a new branch for lupeol synthase that was closely related to the beta-amyrin synthase cluster, whereas RsM2 was found in the first branch of the multifunctional triterpene synthase evolved from lupeol to beta-amyrin synthase. Based on these sequence comparisons and product profiles, we discuss the molecular evolution of triterpene synthases and the involvement of these genes in the formation of terpenoids in mangrove leaves.

Cloning and Functional Expression of Cycloartenol Synthases from Mangrove SpeciesRhizophora stylosaGriff. andKandelia candel(L.) Druce

To obtain cDNAs encoding oxidosqualene cyclase (OSC), we cloned two cDNAs, KcCAS and RsCAS, from roots of Kandelia candel (L.) Druce and leaves of Rhizophora stylosa Griff. by homology based PCR method respectively. The deduced amino acid sequences of both OSCs showed 82% homology to cycloartenol synthases from Lotus japonicus (OSC5) and Ricinus cummunis (RcCAS), suggesting that these are cycloartenol synthases of K. candel and R. stylosa. The genes obtained were expressed in a lanosterol synthase deficient Saccharomyces cerevisiae (ERG7) strain, GIL77. GC-MS analysis identified the accumulated reaction product in the yeast transformant to be cycloartenol, indicating that both KcCAS and RsCAS encode cycloartenol synthase.

Restoration of mangrove plantations and colonisation by native species in Leizhou bay, South China

AbstractTo examine the natural colonisation of native mangrove species into remediated exotic mangrove stands in Leizhou Bay, South China, we compared soil physical–chemical properties, community structure and recruitments of barren mangrove areas, native mangrove species plantations, and exotic mangrove species—Sonneratia apetala Buch.Ham—between plantations and natural forest. We found that severely degraded mangrove stands could not regenerate naturally without human intervention due to severely altered local environments, whereas some native species had been recruited into the 4–10 year S. apetala plantations. In the first 10 years, the exotic species S. apetala grew better than native species such as Rhizophora stylosa Griff and Kandelia candel (Linn.) Druce. The mangrove plantation gradually affected soil physical and chemical properties during its recovery. The exotic S. apetala was more competitive than native species and its plantation was able to restore soil organic matter in about 14 years. Thus, S. apetala can be considered as a pioneer species to improve degraded habitats to facilitate recolonisation by native mangrove species. However, removal to control proliferation may be needed at late stages to facilitate growth of native species. To ensure sustainability of mangroves in South China, the existing mangrove wetlands must be managed as an ecosystem, with long‐term scientific monitoring program in place.

Comparison of flooding-tolerance in four mangrove species in a diurnal tidal zone in the Beibu Gulf

The flood tolerance of four mangrove species, Aegiceras corniculatum (L.) Blanco (AC), Avicennia marina (Forsk.) Vierh. (Am), Bruguiera gymnorrhiza (L.) Savigny (Bg) and Rhizophora stylosa Griff. (Rs) was examined in a field trial conducted from August 2004 until August 2005 in a diurnal tidal zone in Yingluo Bay, Guangxi province, China. In a section of tidal flat, three replicate artificial platforms were constructed for seedling cultivation. Eight different tidal flat elevation (TFE) treatments were created on each platform. After one year of cultivation under the TFE treatments, the survival rate and growth parameters of seedlings were measured. Seedlings of A. corniculatum and A. marina seedlings survived all treatments. The survival rate of B. gymnorrhiza and R. stylosa seedlings, however, decreased sharply as the TFE fell; in any treatment, fewer B. gymnorrhiza seedlings survived than R. stylosa seedlings. Stem elongation in A. corniculatum and A. marina seedlings was significantly increased by lower TFEs. Lower TFE treatments also increased stem heights in B. gymnorrhiza and R. stylosa seedlings; however, growth was significantly higher as TFE increased. Leaf number, leaf conservation rate and leaf area per seedling changed relatively little among treatments in A. corniculatum and A. marina seedlings, while these three indexes in B. gymnorrhiza and R. stylosa seedlings all decreased dramatically with decreasing TFE. A. marina seedlings reached a higher neonatal biomass at lower TFE treatments, whereas A. corniculatum seedlings attained a higher biomass under moderate TFEs. In contrast, B. gymnorrhiza and R. stylosa seedlings accumulated more biomass in the higher TFEs habitats. Biomass partitioning among the components of both A. corniculatum and A. marina seedlings changed evenly; however, A. corniculatum accumulated more biomass in the leaf while A. marina accumulated more in the stem. The TFE treatments greatly influenced biomass partitioning in B. gymnorrhiza and R. stylosa seedlings, with a change from stem to leaf as the TFE increased. Generally speaking, the rank order of tolerance to flooding among these four mangrove species in the diurnal tidal zone was, from most to least tolerant, A. marina > A. corniculatum > R. stylosa > B. gymnorrhiza. This conclusion is consistent with the general pattern of natural mangrove species zonation along the Chinese coast in the Beibu Gulf. The critical tidal levels for afforestation with these four mangrove species are proposed.

Assembly and persistence of foraminifera in introduced mangroves on Moorea, French Polynesia

Foraminifera inhabiting the muddy substrata within the coastal mangrove forests ( Rhizophora stylosa Griff.) on Moorea, French Polynesia, are distinct from other near shore foraminiferal assemblages around the island. Yet the mangroves were introduced from New Caledonia only in 1937 at Vaianahe Bay; they have since spread to many other sites around Moorea. They invade and occupy mud substrata below Paspalum marshes, the marshes themselves and mud under overhanging Hibiscus stands. The mangrove foraminifera cluster uniquely among themselves when compared to other lagoonal habitats, including those invaded by the mangroves. Thus, the introduction of mangroves has apparently allowed the development of a new community or assemblage of foraminifera. Mangrove foraminifera include Ammoastuta salsa, Ammotium tepida, Paratrochammina stoeni, Reophax cf. R. bacillaris, Trichohylus aguayoi, Trochammina inflata, and other subsidiary species of Ammonia, Elphidium, Quinqueloculina, Cornuspira, and Rosalina. Arenoparrellla mexicana , a characteristic species in mangroves elsewhere, is absent from Moorea, perhaps because it was never there like the mangroves themselves. The mangrove species cluster midway between those of shallow-water lagoonal mud, salt grass Paspalum marshes, and the muddy habitats below Hibiscus trees, even when they occur at similar elevations above or below sea level. The foraminifera in the unique cluster in the mangroves were not introduced with the initial mangrove trees, as the trees were established from propagules carried to the site by humans. The cluster is also found in other newer stands on the island that were colonized by floating propagules. The foraminiferal mangrove assemblage at Moorea is a more recent amalgamation of taxa recruited from the species pools in the associated salt grass Paspalum, Hibiscus and shallow-water lagoonal mud habitats. This recruitment happened quickly, most likely as soon as the mangroves grew to sufficient size to trap fine sediment and organic material, as these species are constantly transported about the lagoon chiefly by birds, rafts of algae or foam, and turbidity created by winds and storms. Some but not all foraminiferal species from these environments were able to occupy the new mangrove habitat. This indicates that the unique clusters of foraminifera have no biologic unity, but are simply associations of species that tolerate slightly different but similar environments at different elevations and with increased organic content, and with decreased wave action caused by mangrove roots. Previous studies of foraminiferal and other associations also indicate that in many situations marine organisms are not necessarily dependent on other specific species. Even in seemingly structured reef and rocky-shore communities with geologic histories of similar communities over thousands of years, the rapidity with which dispersal of larvae, eggs, or adult organisms takes place, and similar environmental conditions maintain this similarity of community, not principally any biologic dependence of species upon one another.

Floral abortion and pollination in four species of tropical mangroves from northern Australia

We assessed natural rates of floral abortion in four common mangrove species from northern Australia and subsequently manipulated pollination experimentally. Sonneratia alba J. Smith exhibited the highest rate of fruit set of the four species (23%), indicating this mangrove was best able to utilise the natural pollination opportunities provided. Fruit set in S. alba appeared, however, to be pollinator limited, as large increases in fruit set occurred after manual cross-pollination of flowers. Avicennia marina (Forsk.) Vierh. had the highest rate of natural pollination, but fruit set was lower (15%) and appeared to be impeded by resource limitations. Although a range of insects visited Ceriops australis (C.T. White) Ballment, T.J. Sm & Stoddart , the rate of fruit set was low (3%) and the capacity for flower fertilisation limited, despite evidence of autogamy in this species. There was an indication of both resource and pollinator limitation in C. australis. Rhizophora stylosa Griff. exhibited limited fruit set (0.5%), possibly due to limiting maternal resources and the lack of adaptation of flowers to either animal or wind pollination. Large increases in fruit set were recorded after manual cross-pollination of R. stylosa flowers. R. stylosa and C. australis, characterised by resource rich propagules with long periods of development, both aborted a large proportion of propagules during the fruit maturation process.