Species abundance fluctuations over 31 years are associated with plant–soil feedback in a species‐rich mountain meadow

Abstract

1. Increasing evidence suggest that plant-soil interactions play an essential role in plant community assembly processes. Empirical investigations show that plant species abundance in the field is often related to plant-soil biota interactions; however, the direction of these relations have yielded inconsistent results. 2. We combined unique 31-year long field data on species abundances from a species-rich mountain meadow with single time point plant-soil feedback greenhouse experiments of 24 co-occurring plant species. We tested whether these relations were dynamic in time, whether coupled increases and decreases in abundance between years were related to plant-soil feedback and whether these changes were underlain by years in which manuring was applied. 3. The prevailingly negative relationship between plant-soil feedback and plant relative abundance in the field was significantly time-dependent, which may reconcile the contrasting results in literature. Furthermore, significantly coupled oscillations appeared between species relative abundance changes and plant-soil feedback, which were likely moderated by years in which manuring was applied. Our results are consistent with the notion that the more abundant species are stabilised by negative plant-soil feedback, and the less abundant species co-vary with the fluctuations of these more competitive species. 4. Synthesis. Our results project plant-soil feedback as an important regulatory mechanism in plant communities, operating in conjunction with species' competitive ability and soil nutrient availability. We suggest that negative feedback is particularly prominent in more abundant plant species that profit from more readily available soil nutrients than less abundant species with positive feedback. Negative plant-soil feedback may thus prevent more abundant plant species from out-competing less abundant plant species, facilitating stable species coexistence .

Plant life‐history traits rather than soil legacies determine colonisation of soil patches in a multi‐species grassland

“…Such sequential replacements result in high, fine‐scale dynamics in plant communities, which is line with observations in grassland communities stable in plant species numbers, that is, where plant species successfully coexist (Herben et al, 1997; Herben, Krahulec, Hadincová, & Skálová, 1993; Humphrey & Pyke, 1998; Palmer & Rusch, 2001; van der Maarel & Sykes, 1997). Moreover, our previous findings in the species‐rich mountain meadow are consistent with the proposed framework as we found that fluctuations in relative abundance of species responding negatively and positively to their own conditioned soil were coupled in time: in years that the generally higher abundant negative feedback species (superior competitors) decreased, the lower abundant positive feedback species (inferior competitors) increased, and vice versa (in ‘t Zandt et al, 2021). This balance may result from a dependency of the fast colonising, inferior competitors on the release of soil patches by slow colonising, superior competitors, akin to the proposed framework (Figure 5).…”

“…We selected plant species that naturally co‐occur in a species‐rich mountain meadow of which plant species abundances are stable on the large scale (community), but highly dynamic on the local scale (individuals) (Herben et al, 1995; Herben, Krahulec, Hadincová, & Kovářova, 1993; Herben, Krahulec, Hadincová, & Skálová, 1993). We previously showed that these fluctuations in abundance were linked to species‐specific soil conditioning effects (in ‘t Zandt et al, 2021). The selected species were grown in communities in an outdoor mesocosm facility in unconditioned soil with bare soil patches containing soil conditioned by one of four focal plant species, or a soil mixture of all four species as a non‐specific, control soil.…”

Multi‐dimensionality as a path forward in plant‐soil feedback research

“…We propose that future PSF studies should strive for a higher level of resolution regarding which components of the soil communities influence plants and vice versa within PSF experiments. For starters, the field needs to thoroughly evaluate to what degree inoculation approaches are successful at establishing intended soil communities (Howard et al, 2017). Further, we propose that more groups of taxa need to be considered as drivers of PSF responses (e.g.…”

“…The great variation observed in how different species and genetic lineages vary in their feedbacks with soil biota has increasingly led researchers to question the role of phylogeny (e.g. in 't Zandt et al., 2021). These could arise if the pool of species used in the experiment share a certain degree of co‐evolution with pathogenic or mutualistic soil biota (Wandrag et al., 2020): closely related plant species often show morphological and chemical resemblance which may shape plant interactions with soil biota.…”

Dynamic plant–soil microbe interactions: the neglected effect of soil conditioning time

“…Chung et al ., 2019; in 't Zandt et al. , 2021), it should be possible to more properly place experimental results in a natural context to better predict how soil microbes influence plant community assembly.…”