Greenness trends and carbon stocks of mangroves across Mexico

Abstract

Mangroves cover less than 0.1% of Earth's surface, store large amounts of carbon per unit area, but are threatened by global environmental change. The capacity of mangroves productivity could be characterized by their canopy greenness, but this property has not been systematically tested across gradients of mangrove forests and national scales. Here, we analyzed time series of Normalized Difference Vegetation Index (NDVI), mean air temperature and total precipitation between 2001 and 2015 (14 years) to quantify greenness and climate variability trends for mangroves not directly influenced by land use/land cover change across Mexico. Between 2001 and 2015 persistent mangrove forests covered 432 800 ha, representing 57% of the total current mangrove area for Mexico. We found a temporal greenness increase between 0.003 [0.001-0.004] and 0.004 [0.002-0.005] yr −1 (NDVI values±95%CI) for mangroves located over the Gulf of California and the Pacific Coast, with many mangrove areas dominated by Avicennia germinans. Mangroves developed along the Gulf of Mexico and Caribbean Sea did not show significant greenness trends, but site-specific areas showed significant negative greenness trends. Mangroves with surface water input have above ground carbon stocks (AGC) between 37.7 and 221.9 Mg C ha −1 and soil organic carbon density at 30 cm depth (SOCD) between 92.4 and 127.3 Mg C ha −1 . Mangroves with groundwater water input have AGC of 12.7 Mg C ha −1 and SOCD of 219 Mg C ha −1 . Greenness and climate variability trends could not explain the spatial variability in carbon stocks for most mangrove forests across Mexico. Site-specific characteristics, including mangrove species dominance could have a major influence on greenness trends. Our findings provide a baseline for national-level monitoring programs, carbon accounting models, and insights for greenness trends that could be tested around the world.

Environmental Controls on the Temporal Evolution of Energy and CO2 Fluxes on an Arid Mangrove of Northwestern Mexico

“…(2018) also found that time‐series of 15‐years of four vegetation indexes (gNDVI, EVI, and NDVI) were significantly and negatively correlated with in situ data of temperature and salinity in the Yucatán Peninsula. However, the correlation NDVI‐ambient temperature is site‐specific and can be positive, especially in those sites found in temperate‐humid ecosystems where temperature is not the limiting factor for mangrove growth (Songsom et al., 2019; Vázquez‐Lule et al., 2019). Furthermore, the phenology inferred by Sentinel‐NDVI in our site agreed with field observations of mangrove phenology in the Gulf of California.…”

“…In Mexico, they are mostly found in narrow strips along the coastline of the Gulf of California and adjacent to coastal deserts. Sonora and Baja California Sur, two Mexican states that border the Gulf of California, have a mangrove extension of 9,353 (1.42% of the national total) and 24,327 hectares (3.7% of the national total) respectively (Vázquez‐Lule et al., 2019). Although mangroves only occupy 1% of the arid ecosystems of northwestern Mexico, they can store about 28% of the total regional belowground carbon pool (Ezcurra et al., 2016; Ochoa‐Gómez et al., 2019).…”

Soil Organic Carbon Across Mexico and the Conterminous United States (1991–2010)

“…Respectively, the tropical or subtropical broadleaf evergreen forests are the most productive ecosystems of Mexico (Murray‐Tortarolo et al, ). The wetland category, with high carbon sequestration potential, includes mangroves (and other coastal wetlands), which have been recognized as the ecosystems with higher carbon storage capacity from the site‐specific to the global scales (Adame et al, ; Atwood et al ; Vázquez‐Lule et al, ). Our results represent benchmarks for SOC monitoring across these land cover classes.…”

Tidal Wetland Gross Primary Production Across the Continental United States, 2000–2019

“…An initial investigation showed that~1/3 of the apparent GPP increase from 2000 to 2019 was due to interpolation. We are currently investigating this topic further, as other work has found increasing GPP over time for mangroves in Mexico (Vázquez-Lule et al, 2019). One potential future avenue is to use data from NOAA's Coastal Change Analysis Program to map dynamic changes , although this approach could coarsen the spatial resolution and bring greater wetland classification errors.…”