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

Abstract

This work explored the environmental factors that control the temporal dynamics of vertical energy and carbon fluxes between the atmosphere and arid mangroves located on the coastline of the Gulf of California, Mexico. Net ecosystem exchange (NEE), latent (λE) and sensible heat (H) exchange fluxes were estimated in situ using the eddy covariance technique along with meteorological and hydrological observations during the period November 2017 through November 2019. Moreover, multiyear mangrove phenology at footprint-scale was tracked using remotely sensed vegetation greenness data from Sentinel-2. Our results suggest that the seasonal energy partition and the magnitude of NEE is highly coupled with seasonal changes in the level of tidal flooding, vapor pressure deficit (VPD) and temperature. Low tidal levels facilitate heat transmission to the atmosphere leading the energy partition to H, while the increase in flooding and VPD facilitates the transmission of water vapor resulting in λE dominance. The lowest rate of NEE was observed during the months of highest tidal flooding (June-August) while the highest seasonal rate of NEE matched with the lowest mean flood levels (March-May). Estimated annual NEE for 2018 was −745.3 gC m −2 y −1 while for 2019 was −307.4 gC m −2 y −1 . Our findings suggest a possible trend of decrease in the capacity of carbon sequestration of arid mangroves with rising sea levels and air temperature as a result of global warming.GRANADOS-MARTÍNEZ ET AL.

Quantifying mangrove carbon assimilation rates using UAV imagery

“…In addition, future research should assess whether the proposed methodology can effectively evaluate spatial and temporal changes in carbon assimilation rates in mangroves, which may vary depending on the season. Further, ongoing investigation should compare our results with those obtained from eddy covariance methods, which have been applied in mangroves worldwide, but are scarce in arid environments (e.g., 27 , 95 ). As the gold standard in large-scale carbon flux monitoring 24 , eddy-covariance methods might provide more accurate measurements of canopy-scale ecosystem function than the point-scale gas exchange chamber used herein.…”