Direct and legacy‐mediated drought effects on plant performance are species‐specific and depend on soil community composition

Abstract

Droughts affect plant communities, but their impacts may be mediated by soil biota. Soil communities may ameliorate drought stress, and droughts may leave legacies of altered soil communities that may affect future plant growth. However, it is not yet understood which groups of soil biota in particular affect plant performance under drought, nor which groups contribute to drought‐legacy effects on future plant growth. We hypothesized that increasing soil‐community complexity ameliorates drought stress and that drought‐legacy effects are species‐specific and soil‐community‐dependent. To test these hypotheses, we performed a two‐phase experiment with six grassland species. In the first phase, we examined plant performance under drought and ambient conditions, in soils inoculated with a sterilized inoculum, or increasingly complex soil communities created by wet‐sieving through 20‐, 40‐ and 200‐µm mesh sieves. In the second phase, we examined drought‐legacy effects on conspecific plant performance. We separately analysed plant performance in both phases, and integrated data from both phases using structural equation models. Drought effects on first‐phase root biomass depended on soil inoculum, and this interaction differed among plant species, while effects on shoot biomass differed among species, but did not depend on inoculum. Only one species experienced drought‐stress‐ameliorating effects of soil biota. Drought‐legacy effects on plant performance were positive, but depended on soil inoculum in case of root biomass, and on soil inoculum and species identity in case of shoot biomass. Drought‐legacy effects were often mediated by first‐phase biomass. In some species this effect was independent of inoculum, suggesting an abiotic legacy effect. In others, low first‐phase biomass corresponded with high second‐phase performance in presence of the most complex soil community. We conclude that drought‐legacy effects on plant performance were soil‐community‐dependent but positive, suggesting that plants establishing after drought may benefit from increased nutrient availability and more positive impacts of soil biota.

Plant-soil feedback: incorporating untested influential drivers and reconciling terminology

“…Given that severe drought events are expected to increase as climate change advances (Pörtner et al 2022), understanding the effect of this extrinsic abiotic driver on PSF has become paramount. Drought leaves a strong signature in the soil, changing nutrient availability and stoichiometry (Gao et al 2020) and soil microorganism community composition (Canarini et al 2021;Meisner et al 2018), consequently influencing plant growth (Buchenau et al 2022). Such drought effects can have implications for ecosystem processes such as carbon cycling (Fuchslueger et al 2016).…”

Drought legacies and ecosystem responses to subsequent drought

“…A major driver of drought legacies in grasslands is related to drought‐induced changes in plant–soil feedbacks (PSFs), that is the interactions between plants, soil organisms, and abiotic soil factors, which lead to altered plant composition and performance and have cascading effects on ecosystem properties (Buchenau et al, 2022; Crawford & Hawkes, 2020; DeVries et al, 2019; Peguero et al, 2019; Preece & Peñuelas, 2016; Pugnaire et al, 2019; van der Putten et al, 2013; van der Putten et al, 2016; Williams & DeVries, 2020). Drought can influence PSFs e.g.…”

Soil legacies of extreme droughts enhance the performance of invading plants

“…It is well known that the high abundance of R. solani can severely damage their host plants 69,70 . A strong reduction of root biomass in our study during extreme drought could also have reduced the abundance of such endophytic fungi 71,72 , which subsequently promoted the performance of invading plants 73 . A recent study further suggested that fungal community responses to drought were closely related to root trait responses to soil water scarcity although pathogenic fungal responses were rather weak to drought 74 .…”

“…No reuse allowed without permission. subsequently promoted the performance of invading plants 73 . A recent study further suggested that fungal community responses to drought were closely related to root trait responses to soil water scarcity although pathogenic fungal responses were rather weak to drought 74 .…”