Coastal Mangrove Ecosystems Research Articles

Ecological influence of exotic plants of Sonneratia apetala on understory macrofauna

The study aims to compare the differences of macrofauna communities of wetlands at 3-year-forestage, 5-year-forest-age Sonneratia apetala artificial mangroves, 5-year-forest-age Kandelia candel artificial mangroves with the same restoration background, and the naked tidal flat in the Qi’ao Island Mangrove Nature Reserve of Zhuhai, Guangdong Province. The results show that there were significant structural differences in macrofauna communities among four kinds of habitats. The increase of biomass and species diversity of macrofauna at 3-year-forest-age S. apetala artificial mangroves was obviously faster than that at 5-year-forest-age K. candel artificial mangroves whose average tree height was close to that of 3-year-forest-age S. apetala artificial mangroves. The BIOENV analysis shows that it was related to the rapid growth of S. apetala, which rapidly changed the light level and shading conditions in the forests. The 5-year-forest-age S. apetala artificial mangroves had lower macrofauna species diversity but higher density and biomass than K. candel artificial mangroves with the same forest age. This was due to the rapid changes of physical and chemical properties of habitat soil by the ecological restoration of S. apetala artificial mangroves as well as the changed food sources possibly caused by the leaf-litter of such non-indigenous mangrove species S. apetala. However, further survey should be conducted on whether there are any negative ecological impacts of large-scale cultivation of S. apetala on macrofauna communities, so as to evaluate correctly S. apetala’s role in the restoration of coastal mangrove ecosystems.

Genus Pellacalyx - a new record for flora of Vietnam

In the world, Pellacalyx with 7-8 species distributed in China, Indonesia, Malaysia, Myanmar, Philippines, Thailand. In Vietnam, it is the first time, we confirm genus Pellacalyx distributed in Vietnam, this genus with 1 species Pellacalyx yunnanensis H. H. Hu. In Vietnam, genera Pellacalyx and Carallia are distinguished from other genera of Rhizophoraceae by living form and germination of seeds. The other genera with some important characters as “trees of inland ecosystems; seeds not germinating while attached to parent plant” and Pellacalyx and Carallia with some important characters as “trees or shrubs of coastal mangrove ecosystems; seeds germinating and hypocotyls growing from fruit while attached to parent plant”. Pellacalyx is distinguished from Carallia by some characters: Carallia: Stipules twisted, overlapping; stamens attached to disk. Pellacalyx: Stipules flat, free; stamens attached to mouth of calyx tube. We named Pellacalyx yunnanensis “Duoc bau ruou can” by two main reasons: Living form of the species is the same to Carallia -Duoc can. Calyx urceolate. Some main characters of Pellacalyx yunnanensis: Trees (3-)15 m tall. Branchlets thick, with hairs. Leave opposite or whorled, oblanceolate, oblong or lanceolate, 13-20 ´ 4.5-6.5 cm, secondary veins 8-9 pairs, base cuneate, margin serrulate, apex shortly acuminate. Pedicel ca. 2 cm, glabrous. Calyx urceolate, 6-7 lobes. Petals 6-7, white. Fruit subglobose, ca. 1.5 cm in diam. Seeds numerous, brownish black, oblong.

Legal Complexity in Natural Resource Management in the Frontier Mahakam Delta of East Kalimantan, Indonesia

It is widely perceived that many governments in developing countries do not exercise effectively their resource control strategies over natural resources use. In coastal areas in particular control has been ineffective on a large scale. As a result in these jurisdictions coastal resource use continues to occur with little or no compliance with existing laws and regulations. Two primary conditions that facilitate such noncompliance include a lack of legal implementation and law enforcement, and administrative competition. Local government officials, particularly street-level bureaucrats, have tended not to hold resource users responsible for noncompliance with formal rules, but instead have tended to sympathize with resource users and report that they understand the reasons for non compliance. This attitude often leads to the establishment of actual resource tenure. This article describes the many arguments that local government officials in Kutai Kartanegara district, Kalimantan, Indonesia, have presented to justify their support of actual resource use. The article analyses why government officials at the local level may sympathize so strongly with actual resource use, and analyses the likely implications of these views on the coastal mangrove ecosystem in the area.

A multiproxy peat record of Holocene mangrove palaeoecology from Twin Cays, Belize

The extent and function of coastal mangrove ecosystems are likely to be influenced by future changes in sea level. Multiple proxies of past mangrove ecosystems preserved in a 780 cm long peat core (TCC2) taken from Twin Cays, Belize, record palaeoecological changes since ~8000 cal. yr BP. The proxies included pollen and the stable-isotope (C, N and O) compositions of mangrove leaf fragments. Rhizophora mangle (red mangrove) has been dominant at this site on Twin Cays for over ~8000 years. Variations in δ13 C and δ15N suggest past changes in stand structure between dwarf, transition and tall R. mangle through the Holocene. Marked changes in the δ18O (up to ~4‰) of mangrove leaf fragments throughout TCC2 most likely record variations in the proportion of seawater versus precipitation taken up by past mangroves, reflecting the degree of inundation of the site with seawater resulting from changes in the rate of Holocene sea-level rise. Notably, a decline in peat accumulation rate at ~7200 cal. yr BP correlates with a decrease in the rate of rise in sea level. This was not accompanied by a marked change in the pollen assemblages. However, changes in assemblage composition began to occur ~6300 cal. yr BP, with an increase in Myrsine-type and Avicennia germinans (black mangrove) pollen. An increase in the δ18O between 6100 and 5300 cal. yr BP, which correlates with other records from Central America, indicates a significant increase in the rate of rise in sea level.

Regional processes in mangrove ecosystems: spatial scaling relationships, biomass, and turnover rates following catastrophic disturbance

Physiological processes and local-scale structural dynamics of mangroves are relatively well studied. Regional-scale processes, however, are not as well understood. Here we provide long-term data on trends in structure and forest turnover at a large scale, following hurricane damage in mangrove ecosystems of South Florida, U.S.A. Twelve mangrove vegetation plots were monitored at periodic intervals, between October 1992 and March 2005. Mangrove forests of this region are defined by a −1.5 scaling relationship between mean stem diameter and stem density, mirroring self-thinning theory for mono-specific stands. This relationship is reflected in tree size frequency scaling exponents which, through time, have exhibited trends toward a community average that is indicative of full spatial resource utilization. These trends, together with an asymptotic standing biomass accumulation, indicate that coastal mangrove ecosystems do adhere to size-structured organizing principles as described for upland tree communities. Regenerative dynamics are different between areas inside and outside of the primary wind-path of Hurricane Andrew which occurred in 1992. Forest dynamic turnover rates, however, are steady through time. This suggests that ecological, more-so than structural factors, control forest productivity. In agreement, the relative mean rate of biomass growth exhibits an inverse relationship with the seasonal range of porewater salinities. The ecosystem average in forest scaling relationships may provide a useful investigative tool of mangrove community biomass relationships, as well as offer a robust indicator of general ecosystem health for use in mangrove forest ecosystem management and restoration.

Group points to underlying causes of ecosystem, blodiversity loss

Freshwater diversion, urban water pollution,and overfishing are leading to the decline of some of Pakistan's coastal mangrove ecosystems. In Mexico's Calakmul Biosphere Reserve, near the border of Guatemala, population growth and poverty are pushing forest clearing. Meanwhile, in Chilika Lake in southeast India, changes in economic policies and global markets have led to changes in commercial aquaculture that is partly responsible for the decline of local fisheries and the bird population.These are the conclusions of some of the 10 case studies contained in a World Wildlife Fund (WWF) report, issued on July 6, that examines forests, wetlands, steppes, mangroves, and other habitats to determine the underlying causes for biodiversity loss.