|JOO, EVA - University Of Illinois|
|HUSSAIN, MIR ZAMAN - Michigan State University|
|ZERI, MARCELO - National Early Warning And Monitoring Centre Of Natural Disasters (CEMADEN)|
|MASTERS, MICHAEL - University Of Illinois|
|MILLER, JESSE - University Of Illinois|
|GOMEZ-CASANOVAS, NURIA - University Of Illinois|
|DELUCIA, EVAN - University Of Illinois|
Submitted to: Plant Cell and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2016
Publication Date: 8/15/2016
Citation: Joo, E., Hussain, M., Zeri, M., Masters, M., Miller, J.N., Gomez-Casanovas, N., DeLucia, E., Bernacchi, C.J. 2016. The influence of drought-heat stress on long term carbon fluxes of bioenergy crops grown in the Midwestern US. Plant Cell and Environment. 39:1928-1940.
Interpretive Summary: Ecosystems remove carbon dioxide from the atmosphere for growth. In agricultural ecosystems this growth provides the harvest that is used for food, fiber, and increasingly, fuel. Currently, fuel from agricultural products, referred to as biofuels, are derived from food crops but increasing efforts are being placed on developing crops specifically for bioenergy purposes, referred to as biofuel feedstock crops. In many cases, these feedstocks are perennials because perennials have a longer growing season, require fewer inputs, and, in theory, may be more resilient to climate extremes. This research measures the exchange of carbon between four different agricultural ecosystems and the atmosphere over five years, including a major drought in the Midwestern U.S. in 2012. The four ecosystems are a maize-soybean ecosystem, two perennial grass ecosystems, miscanthus (Miscanthus'×'giganteus) and switchgrass (Panicum virgatum), and a restored native prairie. The primary objective was to assess whether, in response to a major drought, the perennial ecosystems would maintain high levels of carbon uptake and growth relative to what they experience in a more typical year and relative to the annual row crops. The results show that the perennial ecosystem did maintain high productivity during the drought, most likely from the more established and deeper roots.
Technical Abstract: Perennial grasses are promising feedstocks for bioenergy production in the Midwestern US. Few experiments have addressed how drought influences their carbon fluxes and storage. This study provides a direct comparison of ecosystem-scale measurements of carbon fluxes associated with miscanthus (Miscanthus'×'giganteus), switchgrass (Panicum virgatum), restored native prairie and maize (Zea mays) / soybean (Glycine max) ecosystems. The main objective of this study was to assess the influence of a naturally occurring drought during 2012 on key components of the carbon cycle and plant development relative to non-extreme years. The perennials reached full maturity 3-5 years after establishment. Miscanthus had the highest GPP and lowest NEE in 2012 followed by similar values for switchgrass and prairie, and the row crops had the lowest GPP and highest NEE. A post-drought effect was observed for miscanthus. Over the duration of the experiment, perennial ecosystems were carbon sinks, as indicated by negative NECB, while maize/soybean was a net carbon source. Our observations suggest that perennial ecosystems, and in particular miscanthus, can provide high yield and large potential for CO2 fixation even during drought, although drought may negatively influence carbon uptake in the following year, questioning the long-term consequence of its maintained productivity.