View the original news release.
Earth’s ecosystems play an important role in how much carbon is removed from and released into the atmosphere, as they capture and store carbon in soils and plant biomass, and release carbon as carbon dioxide (CO₂) through processes like respiration. Researchers are studying ecosystem carbon dynamics to better understand and predict how the way ecosystems respond to climate change could affect this carbon cycle. EESA scientists Nicola Falco, Yinan He, and Michelle Newcomer recently contributed to a study published in the journal Heliyon to close knowledge gaps about environmental characteristics that affect the carbon emissions in coastal ecosystems.
Coastal-terrestrial aquatic interfaces (TAIs) are transitional ecosystems between land and oceans, which account for at least half of the organic carbon in marine sediments. They also export a significant amount of organic carbon to the ocean and release a large amount of CO₂, deeming these environments important to carbon conservation, monitoring, and management efforts. However, less is known about factors that influence TAI carbon cycling as opposed to upland ecosystems because these environments can have extremely variable characteristics like topography and biodiversity, which can significantly change within just a few meters. The influence of saltwater and freshwater and interactions with ocean and land ecosystems also fosters unique habitats, organisms, and nutrient cycling.
“Coastal ecosystems provide many ecosystem services like water purification, flood control, and recreational activities,” Falco explained. “They are highly productive, playing a crucial role in the global carbon cycle by significantly influencing atmospheric CO₂ levels. Despite these advantages and important implications of their functioning, coastal ecosystems are highly susceptible to the effects of climate change.”
Focusing on the Chesapeake Bay, the largest estuary in the United States, the research team first aimed to identify similarities in environmental characteristics like vegetation and soil type throughout the coastal ecosystem. They used a clustering technique which analyzed datasets of land cover, climate, and more, finding eight areas that were environmentally similar throughout the 4,479 square mile bay (about 95 times the size of San Francisco). The team then used spatial soil respiration data to investigate how soil respiration differed across these eight grouped areas. This showed them what factors primarily influence soil respiration and carbon cycling in each zone and throughout the ecosystem as a whole.
The study found that maximum and minimum temperatures had the largest effect on soil respiration throughout the entirety of the ecosystem, but each zone had different factors that also had significant effects. For example, in more vegetated lands, precipitation largely influenced soil respiration; however, in wetlands, tidal elevation (the difference in height between the highest and lowest water levels) and soil type, specifically how much of the soil consisted of sand particles, largely influenced soil respiration.
“Our results underscore the critical importance of quantifying environmental factors and how they change across entire ecosystems, which enables us to pinpoint the key environmental characteristics driving variability in carbon cycles,” Falco said.
Grouping and analyzing soil respiration in specific zones throughout the Chesapeake Bay can help scientists predict soil respiration in other coastal ecosystems based on specific environment type and characteristics. With new knowledge about soil carbon throughout TAIs and signature environmental factors that influence soil respiration in specific zones, this study can help inform our understanding of how coastal ecosystems may be affected by climate change and how their emissions affect the carbon cycle.
