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Assessing ecosystem collapse risk of fringe mangroves in ecosystems dominated by foundation species

This study investigates the robustness and adequacy of the IUCN Red List of Ecosystems (RLE)’s approach when performing risk assessments using a fringe mangrove ecosystem as a case study, as well as the identification of ecosystems which are more vulnerable to global environmental change.

Ecosystems have immense intrinsic value and provide vital ecosystem services on which human life depends. However, it is human activities themselves that have led to the degradation of many ecosystems globally, reducing their capacity to sustain life. Degradation can eventually lead to ecosystem collapse, a state in which ecosystems - due to the loss of their abiotic and biotic features -  irremediably suffer a change of identity. In the Philippines, fringe mangrove forests are dominated only by two foundation species, which makes them an ideal case study of ecosystems dominated by few foundation species.

  

According to reports, more than 50% of the total area occupied by mangroves in the Philippines has been lost in the last century, and mangrove forests, in general, continue to disappear from Southeast Asia at an estimated rate of 3.6 to 8.1% per year; this suggests that fringe mangroves, like other types of mangroves, could be at greater risk of collapse. As they provide vital ecosystem services that include coastal protection, raw material supply, and carbon sequestration, this would not only result in the loss of biodiversity but would probably have devastating consequences for human populations as well, both locally and globally. Thus, the assessment of collapse risk constitutes a challenge in ecosystems reliant on a few dominant species to perform most of their functions due to the limited amount of suitable and feasible indicators available.

Four years ago, the International Union for the Conservation of Nature (IUCN) adopted the Red List of Ecosystems (LRE) -Categories and Criteria- as a robust and consistent tool for monitoring the risk status of ecosystems in order to plan appropriate conservation actions. Hence,following the LRE protocol, a conceptual model of the key ecosystem processes was applied to the Philippine´s fringe mangrove forests, which along with satellite remote sensing data and existing maps of mangroves, were combined to assess the spatial distribution of the ecosystem, while the Normalized Difference Vegetation Index was used to assess biotic degradation. Key dynamics of the ecosystem under study and the threatening processes were identified to build a conceptual model through which to support the identification of suitable indicators for ecosystem decline assessment.

Consequently, it was possible to find evidence of expected significant threats which may cause the ecosystem’s collapse in the next two decades and affect the forests individually, instead of affecting their entire extension in the Philippines during a single event. The results demonstrate how gaps in the appreciation and understanding of the structure, and functioning of ecosystems are more likely to impede risk assessments of ecosystems characterised by a small number of foundation species.

In addition, satellite remote sensing combined with a derivation of explicit conceptual ecosystem models provides a way to structure efforts to identify suitable indicators, as well as opportunities to overcome many of these challenges, even for ecosystems with relatively poor data. The integration, then, of different types of data through satellite remote sensing, GIS, and modeling approaches is a promising way to meet the unique demands of risk assessment for ecosystems that depend, for example, on a few foundation species.

For more information on this topic, locate and download the article “Assessing ecosystem collapse risk in ecosystems dominated by foundation species: The case of fringe mangroves” by Marshall et al. (2018) in the published assessments section.

 

 

Written by: Mariana Hernández

Style and format: Ariany García

Translation: Claudia Paredes

Provita Jun 15, 2018

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