Carbon stocks of mangroves and losses arising from their conversion to cattle pastures in the Pantanos de Centla, Mexico

Abstract

The conservation of mangroves and other coastal ''blue carbon'' ecosystems is receiving heightened attention because of recognition of their high ecosystem carbon stocks as well as vast areas undergoing land conversion. However, few studies have paired intact mangroves with degraded sites to determine carbon losses due to land conversion. To address this gap we quantified total ecosystem carbon stocks in mangroves and cattle pastures formed from mangroves in the large wetland complex of the Pantanos de Centla in SE Mexico. The mean total ecosystem carbon stocks of fringe and estuarine tall mangroves was 1358 Mg C/ha. In contrast the mean carbon stocks of cattle pastures was 458 Mg C/ha. Based upon a biomass equivalence of losses from the top 1 m of mangrove soils, the losses in carbon stocks from mangrove conversion are conservatively estimated at 1464 Mg CO 2 e/ha. These losses were 7-fold that of emissions from tropical dry forest to pasture conversion and 3-fold greater than emissions from Amazon forest to pasture conversion. However, we found that limiting ecosystem carbon stocks differences to the surface 1 m or even 2 m soil depth will miss losses that occurred from deeper horizons. Mangrove conversion to other land uses comes at a great cost in terms of greenhouse gas emissions as well losses of other important ecosystem services.

Tropical wetlands, climate, and land-use change: adaptation and mitigation opportunities

“…Unfortunately there are so many possible scenarios of management and land use change it is extremely difficult to broadly characterize C gains and losses from these changes. We need more site specific studies such as Kauffman et al (2016) where we have side by side comparisons of C stocks in managed and unmanaged ecosystems. Moreover, we also have little information regarding tropical wetland restoration or enhancement where degraded systems could be used for mitigation opportunities.…”

“…In the Pantanos de Centla of Mexico, Kauffman et al (2016) compared C stocks between intact mangrove systems and cattle pastures formed from mangroves. The mean ecosystem C stock of intact mangroves was 1358 Mg C ha -1 while that of converted cattle pastures was 458 Mg C ha -1 .…”

“…This special issue on tropical wetlands has 11 papers that went through the normal journal review process and are presented starting with a paper by Hribljan et al (2016) focusing on high elevation peatlands in Ecuador, followed by a paper that compares C stocks in tropical peatlands and mangroves in Mexico (Adame and Fry 2016), and then a series of 9 papers assessing mangrove dynamics from Africa Tang et al 2016;Trettin et al 2016), South and Latin America Kauffman et al 2016;McFadden et al 2016), and Southeast Asia MacKenzie et al 2016). The final paper is a global review on impacts of rising ocean water levels on mangrove ecosystems ).…”

Protocols for the measurement, monitoring, and reporting of structure, biomass, carbon stocks and greenhouse gas emissions in tropical peat swamp forests

“…However, in wetland organic soils, the entire belowground pool can be susceptible to loss via tidal and storm surges as well as decomposition following land-cover change. Further, Kauffman et al (2014Kauffman et al ( , 2016 report losses of soil carbon in mangroves at depths exceeding 200 cm. Basuki (2017) finds that peat soils >3 m in depth are affected by deforestation and land cover change.…”

“…Subtracting the differences in these pool sizes yields an estimate of the ecosystem carbon losses to the atmosphere (the large open arrow in Figure 24). This estimate is referred to as the stock difference or stock change approach (IPCC 2006;Kauffman et al 2016). …”