Mangrove and Freshwater Wetland Conservation Through Carbon Offsets: A Cost-Benefit Analysis for Establishing Environmental Policies (original) (raw)
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The undervalued contribution of mangrove protection in Mexico to carbon emission targets
Conservation Letters
Mangrove deforestation threatens to release large stores of carbon from soils that are vulnerable to oxidation. Carbon stored in deep soils is not measured in national carbon inventories. Thus, policies on emission reductions have likely underestimated the contribution of mangrove deforestation to national emissions. Here, we estimate that emissions from deforestation and degradation of mangroves in Mexico are 31 times greater than the values used to determine national emission reduction targets for the Paris Agreement. Thus, Mexico has vastly undervaluated the potential of mangrove protection to reduce its emissions. Accounting for carbon emissions from mangrove soils should greatly increase the priority of mangrove forests to receive funding for protection under carbon trading programs.
Forest Ecology and Management, 2019
Mangroves provide multiple ecosystem services (ESs), including fish and wildlife habitat, protection from coastal erosion and flooding impacts, food resources, water quality, carbon sequestration and storage. However, most of the mangrove wetlands structural and functional information useful to evaluate the quality, quantity and monetary value of its ESs has been obtained from studies at tropical latitudes usually dominated by large deltas and extensive coastal lagoon and estuaries. Thus, there is a major data gap for mangrove wetlands located in arid and semi-arid regions due to their limited land cover and location at the boundary of transitional climate gradients. Here we analyze the spatial distribution of mangrove wetlands carbon stocks and net primary productivity (i.e., litterfall and root productivity) in La Paz Bay, an arid coastal region in the Gulf of California, Mexico, where mangrove wetlands are spatially distributed in conspicuously extensive patches. We used this information to qualitatively rank ESs. Three peri-urban mangrove wetland sites (Balandra, Enfermeria, and Zacatecas) were characterized by different degrees of anthropogenic impact. Aboveground biomass (interval: 13.6 to 31.6 Mg C ha −1) was in the lower range when compared globally. The average C storage in mangrove soils (at 45 cm depth) in La Paz Bay is 175 Mg C ha −1 , which is higher than the values reported for other arid zones (≥1 m soil depth: 43-156 Mg C ha −1). Belowground root biomass and productivity values (roots range: 0.22-0.31 Mg C ha −1 ; fine roots NPP: 0.06-0.09 Mg C ha −1 yr −1) were in the lower range. We found distinct differences in aboveground C storage values among sites where mangrove species formed monospecific stands across the landscape within each site. Areas dominated by the species Rhizophora mangle reflected the highest soil C density values (208.9 ± 144.6 Mg C ha −1), followed by Laguncularia racemosa (181.4 ± 118.2 Mg C ha −1) and Avicennia germinans (155.5 ± 72.1 Mg C ha −1). We identified ESs provided by each of the sites, including both cultural (i.e., ecotourism; especially in Balandra), and provisioning (fisheries) services. Our study is a first step in the quantitative assessment of functional and structural properties as ESs of arid mangrove wetlands in La Paz Bay that could be readily translated into robust economic estimates for this arid coastal region.
Kauffman et al 2015 Mangroves and pastures of the Pantanos de Centla Wetlands Ecol Manage
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.
Carbon Pool in Mexican Wetland Soils: Importance of the Environmental Service
Life
Mexican wetlands are not included in Earth system models around the world, despite being an important carbon store in the wetland soils in the tropics. In this review, five different types of wetlands were observed (marshes, swamps, flooded grasslands, flooded palms and mangroves) in which their carbon pool/carbon sequestrations in Mexican zones were studied. In addition, it was shown that swamps (forested freshwater wetlands) sequestered more carbon in the soil (86.17 ± 35.9 Kg C m−2) than other types of wetlands (p = 0.011); however, these ecosystems are not taken into consideration by the Mexican laws on protection compared with mangroves (34.1 ± 5.2 Kg C m−2). The carbon pool detected for mangrove was statistically similar (p > 0.05) to data of carbon observed in marshes (34.1 ± 5.2 Kg C m−2) and flooded grassland (28.57 ± 1.04 Kg C m−2) ecosystems. The value of carbon in flooded palms (8.0 ± 4.2 Kg C m−2) was lower compared to the other wetland types, but no significant diff...
Carbon Stocks of Tropical Coastal Wetlands within the Karstic Landscape of the Mexican Caribbean
Coastal wetlands can have exceptionally large carbon (C) stocks and their protection and restoration would constitute an effective mitigation strategy to climate change. Inclusion of coastal ecosystems in mitigation strategies requires quantification of carbon stocks in order to calculate emissions or sequestration through time. In this study, we quantified the ecosystem C stocks of coastal wetlands of the Sian Ka'an Biosphere Reserve (SKBR) in the Yucatan Peninsula, Mexico. We stratified the SKBR into different vegetation types (tall, medium and dwarf mangroves, and marshes), and examined relationships of environmental variables with C stocks. At nine sites within SKBR, we quantified ecosystem C stocks through measurement of above and belowground biomass, downed wood, and soil C. Additionally, we measured nitrogen (N) and phosphorus (P) from the soil and interstitial salinity. Tall mangroves had the highest C stocks (9876338 Mg ha 21) followed by medium mangroves (623641 Mg ha 21), dwarf mangroves (381652 Mg ha 21) and marshes (177673 Mg ha 21). At all sites, soil C comprised the majority of the ecosystem C stocks (78–99%). Highest C stocks were measured in soils that were relatively low in salinity, high in P and low in N:P, suggesting that P limits C sequestration and accumulation potential. In this karstic area, coastal wetlands, especially mangroves, are important C stocks. At the landscape scale, the coastal wetlands of Sian Ka'an covering <172,176 ha may store 43.2 to 58.0 million Mg of C.
Threats, conservation actions, and research within 78 Mexican non-coastal protected wetlands
We reviewed scientific literature and internet sources related to types of threats, conservation actions, and focus of research implemented in 78 Mexican non-coastal wetlands. These sites have been established as Natural Protected Areas, Ramsar Sites, and/or Important Bird Areas, and thus hold the highest priority for wetland conservation in Mexico. According to the information obtained, the main threats within these sites included "agriculture and aquaculture", "biological resource use", and "pollution". The most commonly reported conservation action was "education and awareness", and the least frequent were "law and policy", as well as "livelihood, economic, and other incentives". The most popular research focus was "site description", whereas the least frequent were "conservation", and "impacts". These results suggest that both management and research fail at addressing existing threats within most sites. Our study is useful for identification of information gaps, and conservation priorities that should be set within these sites according to available information.
Estuarine, Coastal and Shelf Science, 2013
There has been considerable interest in a recently recognized and important sink in the global carbon pool, commonly referred to as "blue carbon". The major goal of this study was to determine the historical reconstruction of mangrove expansion (Avicennia germinans) into salt marshes (Spartina alterniflora) and its effects on carbon sequestration and soil chemistry in wetland soils of the northwestern Gulf of Mexico. We used bulk stable isotopic, chemical biomarker analyses, and aerial imagery analysis to identify changes in OC wetland sources, and radiotracers ( 137 Cs and 210 Pb) for chronology. Soil cores were collected at two sites at Port Aransas, Texas (USA), Harbor Island and Mud Island.
International Journal of Environmental Research and Public Health
Wetland soils are important stores of soil carbon (C) in the biosphere, and play an important role in global carbon cycles in the response strategy to climate change. However, there areknowledge gaps in our understanding of the quantity and distribution in tropical regions. Specifically, Mexican wetlands have not been considered in global carbon budgets or carbon balances for a number of reasons, such as: (1) the lack of data, (2) Spanish publications have not been selected, or (3) because such balances are mainly made in the English language. This study analyzes the literature regarding carbon stocks, sequestration and fluxes in Mexican forested wetlands (Forest-W). Soil carbon stocks of 8, 24.5 and 40.1 kg cm−2 were detected for flooded palms, mangroves, and freshwater or swamps (FW) wetland soils, respectively, indicating that FW soils are the Forest-W with more potential for carbon sinks (p = 0.023), compared to mangroves and flooded palm soils. While these assessments of carbon...
Valuation of ecosystem services provided by coastal wetlands in northwest Mexico
Coastal wetlands are some of the most productive ecosystems in the world, supporting diverse natural functions and providing important services to human societies. In this context, strategies have recently been developed to maintain these coastal wetlands in a sustainable way, however, wetlands are under pressure, particularly due to land use changes, because they have traditionally been treated as areas of low economic value or even as risky areas for human health. As a result, wetlands have suffered some loss and substantial habitat alteration, which are associated with high social costs. Thus, inventories are required to identify these environments and define and value their services to obtain appropriate information relevant to conservation strategies. This research introduces a spatial component for classifying wetland types and further evaluation of their ecosystem services (ES), assessing their current distribution and extent using standardized remote sensing techniques for wetland mapping. A value transfer approach was performed to generate baseline estimates of the ecosystem services provided by wetlands, validating it through a meta-analysis of a database of wetland estimates, with northwest Mexico wetlands as case study. We found that saltmarshes were the most important wetland in terms of covered area and also that socio-economic variables, such as income, are important in explaining wetland values. The results show that in 2003, a value of 1 billion USD per year was delivered to the local citizens by the surrounding wetlands provided as services and benefits. In a spatially explicit manner, this approach highlights the contribution made by wetlands to the well-being of communities. We argue that in the future design of management plans, the conservation of these environments should be a priority, regarding both, ecologically and economically views.