Ecuador's mangrove forest carbon stocks: A spatiotemporal analysis of living carbon holdings and their depletion since the advent of commercial aquaculture

TL;DR

This study quantifies the carbon loss in Ecuador's mangrove forests caused by shrimp aquaculture since its arrival, highlighting the importance of land use change analysis for accurate carbon stock assessment.

Contribution

It introduces a high-resolution spatiotemporal analysis of mangrove carbon loss due to aquaculture, incorporating land use change into tropical forest carbon studies.

Findings

80% of mangrove carbon lost due to aquaculture displacement

IPCC carbon estimates overstate carbon levels in affected estuaries

Land use change analysis helps target key drivers of carbon loss

Abstract

In this paper we estimate the living carbon lost from Ecuador's mangrove forests since the advent of export-focused shrimp aquaculture. We use remote sensing techniques to delineate the extent of mangroves and aquaculture at approximately decadal periods since the arrival of aquaculture in each Ecuadorian estuary. We then spatiotemporally calculate the carbon values of the mangrove forests and estimate the amount of carbon lost due to direct displacement by aquaculture. Additionally, we calculate the new carbon stocks generated due to mangrove reforestation or afforestation. This research introduces time and land use / land cover change (LUCC) into the tropical forest carbon literature and examines forest carbon loss at a higher spatiotemporal resolution than in many earlier analyses. We find that 80%, or 7,014,517 t of the living carbon lost in Ecuadorian mangrove forests can be attributed to direct displacement of mangrove forests by shrimp aquaculture. We also find that Intergovernmental Panel on Climate Change (IPCC) compliant carbon grids within Ecuador's estuaries overestimate living carbon levels in estuaries where substantial LUCC has occurred. By approaching the mangrove forest carbon loss question from a LUCC perspective, these findings allow for tropical nations and other intervention agents to prioritize and target a limited set of land transitions that likely drive the majority of carbon losses. This singular cause of transition has implications for programs that attempt to offset or limit future forest carbon losses and place value on forest carbon or other forest good and services.