Ecosystem-Wide Impacts of Deforestation in Mangroves: The Urabá Gulf (Colombian Caribbean) Case Study

J F Blanco,L E Urrego,E A Estrada,L F Ortiz

doi:10.5402/2012/958709

Abstract

Mangroves are ecologically important and extensive in the Neotropics, but they are visibly threatened by selective logging and conversion to pastures in the Southern Caribbean. The objective of this paper was to summarize the impacts of both threats on forest structure, species composition, aboveground biomass and carbon reservoir, species introgressions, and benthic fauna populations by collating past and current data and by using an interdisciplinary approach in the Urabá Gulf (Colombia) as a case study. Mangroves in the Eastern Coast have been decimated and have produced unskewed tree-diameter (DBH) distributions due to the overexploitation of Rhizophora mangle for poles (DBH range: 7–17 cm) and of Avicennia germinans for planks and pilings (DBH >40 cm). Selective logging increased the importance value of the light-tolerant white mangrove Laguncularia racemosa, also increasing biomass and carbon storage in this species, thus offsetting reductions in other species. Introgressions (cryptic ecological degradation) by L. racemosa and Acrostichum aureum (mangrove fern) and low densities of otherwise dominant detritivore snails (Neritina virginea) were observed in periurban basin mangroves. Finally, basin mangroves were more threatened than fringing mangroves due to their proximity to expanding pastures, villages, and a coastal city.

Highlights

Mangroves dominate tropical coasts and provide important services to humans, yet they are one of the most threatened ecosystems partially due to deforestation [1,2,3]
In addition to the limited information about rates and drivers of mangrove deforestation, there is a lack of understanding on how specific activities such as selective logging and mangrove reclamation have impacted forest structure, faunal diversity, and services to humans, in the Neotropics
Yarumal-Las Vacas) exhibited fewer trees than expected in the DBH 7–17 cm range, and individuals >40 cm were lacking (Figure 2). This forest exhibited the lowest mean tree diameter and mean density (Table 1), a pattern promoted by selective logging of R. mangle and A. germinans, the species with greater importance value (IVI) in the Eastern Coast (Figure 3)

Summary

Introduction

Mangroves dominate tropical coasts and provide important services to humans, yet they are one of the most threatened ecosystems partially due to deforestation [1,2,3]. With 18% of the region’s mangrove cover, deforestation rate in this country (1.1 and 0.6%) exceeded the South American average (0.69 and 0.18%) in estimates for 1980–1990 and 2000–2005 These figures may be more variable and dramatic at a subcountry level, bearing in mind that coarse-scale inventories using satellite imagery tend to overestimate mangrove cover due to low spatial resolution and heavy cloud cover (as observed in many areas of the Pacific coast and the Urabaregion in the Caribbean coast) [14]. In addition to the limited information about rates and drivers of mangrove deforestation, there is a lack of understanding on how specific activities such as selective logging and mangrove reclamation have impacted forest structure, faunal diversity, and services to humans, in the Neotropics. The ultimate goal of this summary was to contribute insights on the sustainability of current practices of mangrove exploitation

The Uraba Gulf Mangroves and Deforestation

Estimated Biomass and Carbon Reservoirs as Influenced by Deforestation

Selective Logging as a Driver of Species Introgressions and Extinctions

Impacts of Selective Logging and Mangrove Reclamation on Benthic Fauna

Findings

Conclusions