Tracking Human Disturbance in Mangroves: Estimating Harvest Rates on a Micronesian Island

Abstract

Disturbance is an integral component in mangrove forest dynamics, influencing forest structure, composition, and function. The impacts of human disturbance, however, threaten mangrove forests throughout the world. Small-scale wood harvesting on the small Pacific island of Kosrae, Federated States of Micronesia, provided an instructive scenario for exploring the dynamics of human disturbance. Natural disturbances on the island are rare, but the growing island population harvests mangrove trees for firewood and construction materials, placing pressure on the forest. In order to determine recent harvest rates, we estimated gap ages by developing a time scale for mangrove wood decomposition and by quantifying growth rates for Rhizophora apiculata and Bruguiera gymnorhiza seedlings. Stump and log decomposition patterns were useful in aging gaps, although some patterns were more reliable than others. Seedlings of both species added approximately 5 nodes/year depending on light conditions. The island-wide harvest rate was 10% over the last 10 years, but the rates varied widely among different parts of the island. Rhizophora apiculata has been harvested preferentially, and a dearth of young trees where harvesting has been heaviest portends a decline of this highly desired species in the forest. Socio-economic data substantiated some but not all of the trends we observed. Even on a small island, local differences in both natural and anthropogenic factors are important to understanding forest dynamics.

Effect of Anthropogenic Activities on Mangrove Crab Diversity in Cameroon Atlantic Coast

“…Exploitation of mangroves for fuel wood, charcoal production, construction and other uses have been identified as an important pervasive and intrusive threat to this ecosystem [42]. However, the extent of damage depends on intensity, persistence and periodicity of the disturbance [43]. In contrast, the little damage observed in not disturbed stations is probably due to their proximity with the terrestrial evergreen forest from which people collect wood for subsistence needs.…”

Spatial analysis of heavy metals in mangrove estuary at east coast peninsular Malaysia: a preliminary study

“…The mangrove also deliver steadying for coastal landform and mitigation of erosion [4]. Mangrove forest shows decreasing in biodiversity result from mangrove forest ecosystems disturbance [5]. Generally, the mangrove systems (river, estuary and wetland) obtain numerous of pollutants and have become an immense pollution sink in recent decades [6].…”

“…Generally, the mangrove systems (river, estuary and wetland) obtain numerous of pollutants and have become an immense pollution sink in recent decades [6]. Due to the increasing rate of human population, the exploration of mangrove forest through human activities such as logging activities, deforestation, agricultural land and waste from industry gives negative impact to the environment and also to water quality of mangrove forest [5,[7][8][9]. Scornfully, heavy metals are one of the main anthropogenic toxic compounds reported high in mangrove ascending from several sources including agriculture runoff [6].…”

Inventorying, Mapping and Monitoring of Mangroves towards Sustainable Management of West Coast, India

“…In addition to the lack of appropriate regulatory mechanisms to implement the coastal zone norms and land use land cover (LULC) changes due to socio-economic consequences have contributed to the sharp decline of mangrove cover [13,14]. Rampant expansion of aquaculture farms and the demand of hard wood in construction sector have led to the removal of mangroves [15][16][17]. This emphasises the need for integrated approaches involving inventorying, mapping and monitoring including sustainable resource management with land-use planning for conservation based decision making.…”