Wildfire-smoke aerosols lead to increased light use efficiency among agricultural and restored wetland land uses in California's Central Valley
Abstract
There are few observational studies measuring the ecosystem-scale productivity effects of changes in incident diffuse photosynthetically active radiation (PARdiffuse), especially related to wildfire smoke. Climate change-induced increases to the duration and intensity of fire conditions have made smoke a common occurrence across western North America, with largely unquantified ecosystem feedbacks. Under equivalent amounts of radiation, increased atmospheric particulate matter could lead to a boost in productivity as scattering redistributes photons throughout multi-layer canopies. In this work, we leverage a meso-network of eddy covariance measurement sites across a unique array of managed and restored C3 and C4 canopy types to understand how recent wildfire smoke affected ecosystem productivity during the summer of 2018, an especially smoky year in the agriculturally productive Central Valley.
We find that PARdiffuse increased by more than a third compared to the previous growing season, while total PAR (PARtotal) was only slightly diminished. These conditions caused light use efficiency increases of 1.6-2.8% for every 1% increase in diffuse fraction, with the highest sensitivity to diffuse fraction exhibited by crops. The tradeoff between enhanced diffuse fraction and reduced PARtotal often resulted in an increase in daily integrated gross ecosystem productivity. The potential negative effect of heightened ozone concentrations coincident with wildfire indicated productivity suppression of a magnitude less than half of the upper envelope diffuse fraction enhancements. In addition to the effects of wildfire smoke, the results of this natural experiment can help validate future predictions of aerosol-productivity feedbacks related to proposed geoengineering strategies and continental-scale air pollution.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGC11F1168H
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 0230 Impacts of climate change: human health;
- GEOHEALTH;
- 4313 Extreme events;
- NATURAL HAZARDS