Warm-season bioenergy grasses and climate change

Photo Credit

USDA photo by Alexis Neukirch

Warm-season grasses are dominant members of many ecosystems worldwide. One reason for their success is a modified photosynthetic pathway which can increase their tolerance of drought and high temperatures. These environmental tolerances combined with a high capacity for biomass production have made some warm-season grasses candidates for bioenergy production.

Although warm-season perennial bioenergy grasses are predicted to perform well as climates continue to change, relatively few studies have examined the responses of these species to experimental changes in precipitation, temperature, and atmospheric CO₂ concentration. Literature searches found that photosynthetic physiology was consistently inhibited by drought but had mixed responses to heatwaves and increasing atmospheric CO₂ concentration. These leaf-level responses to drought, heatwaves, and increasing CO₂ concentration may be challenging to scale up to higher levels (such as the entire plant canopy). Further research is needed to better link responses across these levels.

To be economically viable, bioenergy grasses should be able to grow with limited inputs of fertilizer and irrigation on land that cannot support traditional crops. This will likely require continued breeding efforts to improve bioenergy grass production. Combining advances in genomics with multi-site field trials where genetically diverse plants are grown in environments spanning a range of expected future conditions will help breeders generate bioenergy grasses that are able to maintain or increase productivity under the conditions expected to occur in the coming decades. Knowledge gleaned from theory and climate change experiments may contribute as well.