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Iron supply in the CCE LTER region not only impacts carbon production and export associated with mesoscale circulation features. It also influences phytoplankton growth and species composition at the subsurface chlorophyll maximum layer (SCML), which is a widespread feature during spring and summer. Consistent with regional climate indices, biogeochemical proxies for iron limitation revealed increasing… Read more »

Process studies and related time series measurements reveal the under-appreciated importance of episodic events in the oceanic carbon budget. Spatial and temporal perturbations to the carbon cycle can be associated with (sub)mesoscale features (fronts, eddies, and filaments), which CCE LTER researchers have shown tend to be sites with enhanced phytoplankton and zooplankton biomass and production,… Read more »

More than 60 years of zooplankton census data revealed that some populations respond indirectly to climate changes in two stages: first, ocean circulation responds to wind, then the zooplankton population level responds to ocean circulation. This broadly applicable principle of ‘double integration’ implies that direct correlations with climate variables should be replaced by metrics that… Read more »

Several years of effort have led to an important California Current merged satellite-derived 4 km dataset becoming openly available online. The website provides access to regionally optimized remote sensing products and rigorously integrated time series for chlorophyll-a, net primary production, and export flux of carbon from 1996 to 2019.  

In two nested global change experiments, nitrogen (N) and soil moisture jointly constrained the response of biomass production to elevated CO2 over the long term. When both water and N were limited, elevated CO2 did not affect plant biomass. When neither resource was limited, elevated CO2 caused an increase in plant biomass.  

Chronic N addition reduced plant species richness and led to the local extinction of species with efficient N use. Species richness returned to its original level after ceasing the addition of low levels of N. These changes in composition were readily reversed after low levels of N were no longer added. However, species richness did… Read more »

Research in the 1990s demonstrated that more diverse herbaceous plant communities are more productive and exhibit less year-to-year variability in net primary productivity (NPP). Recently, this positive relationship has also been observed in forest communities. New CDR LTER research also indicates that the relationship increases in strength with experiment duration in grasslands. Recent network-wide synthesis… Read more »

Contradicting classical estuary models, FCE LTER research demonstrated that marine nutrient supplies (rather than freshwater nutrient supplies) control coastal productivity gradients via daily tides, episodic storm surges, and hidden groundwater upwelling. Saltwater intrusion amplifies marine pulses by increasing connectivity to the sea and liberating phosphorus from limestone. Sea level projections based on long term data… Read more »

Long term data reveal that multiple types of disturbances — including cold snaps, fires, droughts, floods, and tides — play a strong role in shaping coastal ecosystems. Tropical storms can be beneficial by connecting upstream and downstream food webs and dispersing mangrove propagules into disturbance-generated canopy gaps. They also deliver phosphorus rich mineral deposits that… Read more »

Rising seas can stimulate the inland transgression of mangroves and amplify carbon gains (as observed in historic carbon budgets based on long term flux data, paleoecology, and remote sensing). However, FCE LTER studies, experiments, and models show that carbon losses can exceed increases where saltwater invades freshwater marshes, resulting in abrupt elevation loss (collapse) that… Read more »