Climate change effects on biomass and greenhouse gas emissions are ameliorated by nontoxic endophytes in southeastern USA transition zone tall fescue pastures

Abstract

Background

The plant–microbe interaction between tall fescue and its endophyte Epichloë coenophiala can affect ecosystem responses to changing rainfall patterns and increasing temperatures. Endophyte-infected (E+) stands often exhibit improved stress tolerance and differing soil greenhouse gas (GHG) emissions compared to endophyte-free (E−) stands. However, it is unknown if mammalian nontoxic endophyte (NTE) strains introduced into some tall fescue cultivars confer differing stress tolerances or reduce soil GHG emissions.

Methods

We quantified the impact of fescue-NTE symbioses in Jesup and Texoma on biomass and GHG emissions in response to increased temperature (+3°C) and altered precipitation (50% lengthened interval between events) using a factorial design in the United States southeastern transition zone over 2 consecutive years (2016–2017).

Results

Endophyte infection increased aboveground biomass 24% across years, whereas heat decreased aboveground biomass 17% across tall fescue cultivars and years. Endophyte infection reduced CO₂ emissions under both ambient (for Jesup) and heated conditions (for Texoma), but endophyte infection also increased NH₃ volatilization for Texoma (no effect for Jesup), especially under the hottest and driest treatment.

Conclusions

Fescue-NTE symbioses may improve pasture resiliency with projected climate change for the study region.