Belowground carbon allocation, root trait plasticity, and productivity during drought and warming in a pasture grass

Abstract

Sustaining grassland production in a changing climate requires an understanding of plant adaptation strategies, including trait plasticity under warmer and drier conditions. However, our knowledge to date disproportionately relies on aboveground responses, despite the importance of belowground traits in maintaining aboveground growth, especially in grazed systems. We subjected a perennial pasture grass, Festuca arundinacea, to year-round warming (+3 ℃) and cool-season drought (60% rainfall reduction) in a factorial field experiment to test the hypotheses that: i) Drought and warming increase carbon allocation belowground and shift root traits towards greater resource acquisition; ii) Increased belowground carbon reserves support post-drought aboveground recovery. Drought and warming reduced plant production and biomass allocation belowground. Drought increased specific root length and reduced root diameter in warmed plots but increased root starch concentrations under ambient temperature. Higher diameter and soluble sugar concentrations of roots and starch storage in crowns explained aboveground production under climate extremes. However, the lack of association between post-drought aboveground biomass and belowground carbon and nitrogen reserves contrasted with our predictions. These findings demonstrate that root trait plasticity and belowground carbon reserves play a key role in aboveground production during climate stress, helping predict pasture responses and inform management decisions under future climates.

Changes in above- versus belowground biomass distribution in permafrost regions in response to climate warming

“…Extreme warming or extreme drought might also affect the above-versus belowground plant biomass distribution, as high temperature and drought limit photosynthesis (34,45,46) and stimulate closure of leaf stomata (46,47). Our results show that the two largest anomalies in estimated plot-level η occurred under warm and dry summer conditions in 1998 and 2014, with a mean June to August air temperature >15 °C and total precipitation <82 mm (SI Appendix, Table S7).…”

Global warming changes biomass and C:N:P stoichiometry of different components in terrestrial ecosystems

“…The warming effect generally increased belowground biomass while exhibiting a contrasting impact of reducing aboveground biomass in grassland ecosystems (Zhang et al., 2015). Furthermore, the significant increase in plant and root biomass, but not leaf biomass (Figure 4), suggests that altering growth strategies to adjust biomass allocation is a crucial for mitigating global warming in grassland ecosystems (Chandregowda et al., 2023; Zhou, Terrer, et al., 2022a; Zhou, Zhou, et al., 2022b). Moreover, a recent study concluded that experimental warming reduced root biomass within forest ecosystems characterized by relatively low soil C:N ratios (Yaffar et al., 2021).…”

Reduced belowground allocation of freshly assimilated C contributes to negative plant-soil feedback in successive winter wheat rotations

“…However, the much higher root-derived 13 C traced in the soil respiration of W1 compared to W4 10 and 25 DAL provides evidence for accelerated senescence of the root system of W4. Indeed, increased belowground C allocation can help plants cope with biotic and abiotic stresses by increasing rhizodeposition and investing more in extensive root systems (Sanders and Arndt, 2012;Chandregowda et al, 2023). In soil of successive WW cultivation, potentially more C has to be invested into the root or soil microbial activities to deal with the soil pathogens and lower soil mineral content, which could lead to a tradeoff with nutrient uptake and overall plant performance.…”