Plant responses to soil biota depend on precipitation history, plant diversity, and productivity

Abstract

Soil biota are critical drivers of plant growth, population dynamics, and community structure and thus have wide-ranging effects on ecosystem function. Interactions between plants and soil biota are complex, however, and can depend on the diversity and productivity of the plant community and environmental conditions. Plant-soil biota interactions may be especially important during stressful periods, such as drought, when plants can gain great benefits from beneficial biota but may be susceptible to antagonists. How soil biota respond to drought is also important and can influence plant growth following drought and leave legacies that affect future plant responses to soil biota and further drought. To explore how drought legacies and plant community context influence plant growth responses to soil biota and further drought, we collected soils from 12 grasslands varying in plant diversity and productivity where precipitation was experimentally reduced. We used these soils as inoculum in a growth chamber experiment testing how precipitation history (ambient or reduced) and soil biota (live or sterile soil inoculum) mediate plant growth and drought responses within an experimental plant community. We also tested whether these responses differed with the diversity and productivity of the community where the soil was collected. Plant growth responses to soil biota were positive when inoculated with soils from less diverse and productive plant communities and became negative as the diversity and productivity of the conditioning community increased. At low diversity, however, positive soil biota effects on plant growth were eliminated if precipitation had been reduced in the field, suggesting that diversity loss may heighten climate change sensitivity. Differences among species within the experimental community in their responses to soil biota and drought suggest that species benefitting from less drought sensitive soil biota may be able to compensate for some of this loss of productivity. Regardless of the plant species and soil origin, further drought eliminated any effects of soil biota on plant growth. Consequently, soil biota may be unable to buffer the effects of drought on primary productivity or other ecosystem functions as extreme events increase in frequency.

Global patterns and drivers of plant–soil microbe interactions

“…In addition, these findings inform us that the geographic variation of PSF across space may provide a potential mechanism to explain the relationship between species diversity and precipitation (Liang et al., 2022). Under the context of aridity and precipitation change, the change in PSF can also influence community dynamics and diversity at either short‐term or long‐term temporal scales (Lebrija‐Trejos et al., 2023; Lundell et al., 2022).…”

Morphological and physiological traits of dominant plant species in response to mowing in a temperate steppe

“…Plants not only suppress rhizosphere microbial activity by nutrient competition for use of available nutrients by microbial decomposition, but plants also cooperate with rhizosphere microbes and provide resources to microbes for microbial mineralization of available nutrients (Sun et al, 2023). Soil microbes may have positive effects on plant growth (Lundell et al, 2022), and mowing may stimulate the decomposition of organic matter by soil microbes, leading to an increase in nutrient availability in the soil (Hamilton & Frank, 2001). In addition, nonsymbiotic nitrogen‐fixing bacteria associated with grasses may significantly increase plant vegetative growth and grain yield (Kennedy et al, 2004).…”