Abstract
AimsDrought events can alter the composition of plant and soil communities, and are becoming increasingly common and severe due to climate change. However, how droughts affect plant-soil feedbacks is still poorly understood. Plants accumulate species-specific rhizosphere communities, and droughts may have varying impacts across plant species and soil biota. We therefore tested the hypothesis that drought alters plant-soil feedbacks differently among closely related plant species that differ in their preferences for soil moisture.MethodsIn a two-phase greenhouse experiment, we first conditioned grassland soil with seven Geranium species and, as controls, we conditioned soil with a grass species or left soil unplanted. In the second phase, we grew the Geranium species in conspecific, grass-conditioned and unplanted soil, maintained soil moisture at 5 %, 10 % or 20 % (w/w), and determined biomass responses after 35 days.ResultsIndependent of conditioning, plants showed a weaker performance with decreasing soil moisture. Under the driest conditions, soil conditioning by conspecifics most negatively affected relative root weight in comparison to plants growing in unplanted control soil, while the effects of conspecific conditioning on relative root weights were species-specific when compared to plants grown in grass-conditioned control soil.ConclusionsWe conclude that decreased soil moisture modified plant-soil feedback effects on biomass allocation, and that these modifications acted in species-specific ways. However, drought effects on plant-soil feedbacks were subtle, and did not affect overall plant performance. Therefore, plant-soil feedback effects on plant performance during a drought event may be limited in comparison with the direct effects of drought.
Highlights
Climate change increases the frequency of drought events worldwide (Shukla et al 2019), leading to decreasing primary productivity of terrestrial plant communities and alterations of plant community composition (Ciais et al 2005; Kardol et al 2010; Wu et al 2011)
We conclude that decreased soil moisture modified plant-soil feedback effects on biomass allocation, and that these modifications acted in speciesspecific ways
Plant-soil feedback effects on plant performance during a drought event may be limited in comparison with the direct effects of drought
Summary
Climate change increases the frequency of drought events worldwide (Shukla et al 2019), leading to decreasing primary productivity of terrestrial plant communities and alterations of plant community composition (Ciais et al 2005; Kardol et al 2010; Wu et al 2011). Through variation in structural and chemical root traits (Cortois et al 2016; van Dam and Bouwmeester 2016; Wilschut et al 2019), plants accumulate speciesspecific rhizosphere communities of soil organisms, including mutualists, such as mycorrhizal fungi and plant growth-promoting bacteria, and antagonists, such as microbial pathogens and root-feeding nematodes (Berendsen et al 2012; Bezemer et al 2010). Together, these organisms affect the performance of their host and neighbouring plants, and subsequent generations of plant individuals via a mechanism known as plant-soil feedback (van der Putten et al 2013). Plant-soil feedback effects can range from negative to positive, and soil biota can contribute to the natural succession of plant communities, grassland vegetation dynamics and plant rarity through this mechanism (De Deyn et al 2003; Kardol et al 2006; Klironomos 2002; van der Putten et al 1993)
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