The mangroves of Galley Reach, Papua New Guinea

Paijmans, K.; Rollet, Bernard

doi:10.1016/0378-1127(76)90016-5

Cited by 31 publications

(21 citation statements)

References 3 publications

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“…Kairo et al 2002;Bundotich 2007). Globally, the values are in the middle of the reported range for similar forests (322-2,470 stems ha -1 ; Lugo and Snedaker 1973;Paijmans and Rollet 1977;Jimenez et al 1985;Smith 1988). Within Mombasa, natural disturbances are either relatively small or rare, leaving anthropogenic disturbances the principal threat, thus management ought to focus on the anthropogenic element.…”

Section: Discussionmentioning

confidence: 69%

Mangrove forests in a peri-urban setting: the case of Mombasa (Kenya)

Mohamed

Neukermans

Kairo

et al. 2008

Wetlands Ecol Manage

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The structure and regeneration patterns of the peri-urban mangrove vegetation of Mombasa at Tudor creek were studied along belt transects at two forest sites of Kombeni and Tsalu. Based on the species importance values, the dominant mangrove species were Rhizophora mucronata Lam. (Rhizophoraceae) and Avicennia marina (Forssk.) Vierh. (Avicenniaceae). Lumnitzera racemosa Willd., reported in an earlier floristic survey, was not encountered. Tree density varied from 1,264 trees ha -1 at Kombeni to 1,301 trees ha -1 at Tsalu and mean tree height was higher at the former site compared to the latter. The size-class structure at both localities showed the numerical dominance of small trees over larger trees. The spatial distribution pattern of adults and juveniles varied greatly between sites and showed a close to uniform pattern (Morisita's Index I d ( 1) for adult trees, but a tendency to clustered distribution (I d ) 1) for juveniles. The present paper shows that unmanaged but exploited peri-urban mangroves are structurally stressed, having enlarged canopy gaps that are characterised by spatial and temporal site heterogeneity that influences regeneration, implying longer periods for canopy closure. Diversifying uses of mangrove products and establishing reserves as no cut zones with regulated harvesting will minimise canopy gap sizes, and promote conservation practices. The proposed management strategy shall boost the ecosystem resilience to both anthropogenic and natural stressors expected in the peri-urban setting in the long run.

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Section: Discussionmentioning

confidence: 69%

Mangrove forests in a peri-urban setting: the case of Mombasa (Kenya)

Mohamed

Neukermans

Kairo

et al. 2008

Wetlands Ecol Manage

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“…As in other regions of the Gulf of Papua (Percival and Womersley 1975, Paijmans and Rollet 1977, Cragg 1983, Rhizophora apiculata and Bruguiera parviflora are the dominant trees in mangrove forests in higher salinity zones of the Fly River. Group I from our classification of sites, which had R. apiculata and B. parviJVora as dominant species, and B. gymnorhiza and Ceriops decandra as sub-dominants, was very similar to the vegetational association group six of Bunt and Williams (1981) for forests in north-eastern Australia.…”

Section: Discussionmentioning

confidence: 97%

“…These forests often have a gradual transition to mangrove forests (e.g. Paijmans and Rollet 1977). Some of our survey sites were in these transition zones where "mangrove associate" species (Tomlinson 1986), such as Barringtonia racemosa, Diospyros spp., Amoora cucullata and Myristica hollrungi occur.…”

Section: Discussionmentioning

confidence: 99%

“…There have been no detailed assessments of the structure and productivity of mangroves in this region of Papua New Guinea (see Johnstone and Frodin 1982), although Brass (1938) discussed the distribution pattern of some mangrove taxa on islands in the Fly delta. The only data on the within-estuary distribution patterns of mangroves in the Gulf of Papua are for the Purari River (Cragg 1983) and Galley Reach in the eastern Gulf (Paijmans and Rollet 1977), while Boto et al (1984) have provided estimates of forest productivity for some forest types in the Purari delta. The present paper contains data on forest composition and structure for south-western Papua New Guinea in addition to providing productivity Is.…”

Section: Introductionmentioning

confidence: 99%

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Mangrove forest structure and productivity in the Fly River estuary, Papua New Guinea

1991

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Abstract. In April, July and August 1989 and February 1990, the delta region of the Fly River was surveyed to establish the aerial extent of mangrove forests, their species composition, tree densities and basal areas, and potential net primary production. Mangrove forests cover 87 400 ha, mainly on islands within the delta. Twentynine mangrove plant species were recorded, but there were only three major forest types in the delta. Rhizophora apiculata-Bruguiera parviflora forests (hereafter Rhizophora-Bruguiera forests) predominated in regions where river water salinities were > 10%o. These forests covered 31 500 ha and had mean total tree densities and basal areas of 2027 stems ha-1 and 21 m 2 h a -l , respectively. Forests of the palm Nypafruticans (hereafter Nypa forests) covered 38 400 ha, mainly in regions where river salinities were ~ 1 to 10%o, and had mean total densities and basal areas of 4431 stems ha -1 and 38 m 2 ha -l, respectively. Forests dominated by Avicennia marina and/or Sonneratia lanceolata (hereafter Avicennia-Sonneratia forests) predominated on accreting banks of sediment and covered 17 500 ha. In very low-salinity (< 1%0) regions there are large monospecific stands of S. lanceolata. Mean total densities and basal areas for AvicenniaSonneratia forests were 7036 stems ha-1 and 22 m 2 ha-l, respectively. Mean net primary productivity (kg C ha-1 d -x) was estimated to be 26.7, 27.1 and 19.0 for Rhizophora-Bruguiera, Nypa and Avicennia-Sonneratia forests, respectively. Total daily net primary production by all mangrove forests was estimated at 22•4 t carbon. Using assumptions based on work in tropical Australia, it was estimated that ~ 678 t carbon (or 31% of primary production) were exported daily from mangrove forests to the waters of the delta.

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“…In this area, lightning strikes are the primary cause of canopy tree mortality, and the light gaps they produce are sites of vigorous regeneration as evidenced by the high density of saplings as compared to the understory (W. Sousa and B. Mitchell, unpublished data). Lightning gaps have been recognized as key sites of regeneration in mangrove forests throughout the tropics (Craighead 1971;Paijmans and Rollet 1977;Odum et al 1982;Smith 1992;Smith et al 1994;Sousa and Mitchell 1999;Clarke and Kerrigan 2000;Sherman et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Regeneration of Rhizophora mangle in a Caribbean mangrove forest: interacting effects of canopy disturbance and a stem-boring beetle

2003

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Current theory predicts that in low-density, seed-limited plant populations, seed predation will be more important than competition in determining the number of individuals that reach maturity. However, when plant density is high, competition for microsites suitable for establishment and growth is expected to have a relatively greater effect. This dichotomous perspective does not account for situations in which the risk of seed predation differs inside versus outside recruitment microsites. We report the results of a field experiment and sampling studies that demonstrate such an interaction between microsite quality and the risk of propagule predation in mangrove forests on the Caribbean coast of Panama, where it appears to play a key role in shaping the demography and dynamics of the mangrove, Rhizophora mangle. Rhizophora's water-borne propagules establish wherever they strand, but long-term sampling revealed that only those that do so in or near lightning-created canopy gaps survive and grow to maturity. These microsites afford better growth conditions than the surrounding understory and, as importantly, provide a refuge from predation by the scolytid beetle, Coccotrypes rhizophorae. This refuge effect was confirmed with a field experiment in which Rhizophora seedlings were planted at different positions relative to gap edges, from 5 m inside to 20 m outside the gap. Mortality due to beetle attack increased linearly from an average of 10% inside a gap to 72% at 20 m into the forest. The interaction between canopy disturbance and propagule predation may be having a large impact on the composition of our study forests. Being shade-tolerant, Rhizophora seedlings that escape or survive beetle attack can persist in the understory for years. However, the high rate of beetleinduced mortality effectively eliminates the contribution of advance regeneration by Rhizophora saplings to gap succession. This may explain why the shade-intolerant mangrove, Laguncularia racemosa, is able to co-dominate the canopy in low intertidal forests at our study sites.

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The mangroves of Galley Reach, Papua New Guinea

Cited by 31 publications

References 3 publications

Mangrove forests in a peri-urban setting: the case of Mombasa (Kenya)

Mangrove forests in a peri-urban setting: the case of Mombasa (Kenya)

Mangrove forest structure and productivity in the Fly River estuary, Papua New Guinea

Regeneration of Rhizophora mangle in a Caribbean mangrove forest: interacting effects of canopy disturbance and a stem-boring beetle

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