Globally, plant‐soil feedbacks are weak predictors of plant abundance

Abstract

Plant‐soil feedbacks (PSFs) have been shown to strongly affect plant performance under controlled conditions, and PSFs are thought to have far reaching consequences for plant population dynamics and the structuring of plant communities. However, thus far the relationship between PSF and plant species abundance in the field is not consistent. Here, we synthesize PSF experiments from tropical forests to semiarid grasslands, and test for a positive relationship between plant abundance in the field and PSFs estimated from controlled bioassays. We meta‐analyzed results from 22 PSF experiments and found an overall positive correlation (0.12 ≤ truer¯ ≤ 0.32) between plant abundance in the field and PSFs across plant functional types (herbaceous and woody plants) but also variation by plant functional type. Thus, our analysis provides quantitative support that plant abundance has a general albeit weak positive relationship with PSFs across ecosystems. Overall, our results suggest that harmful soil biota tend to accumulate around and disproportionately impact species that are rare. However, data for the herbaceous species, which are most common in the literature, had no significant abundance‐PSFs relationship. Therefore, we conclude that further work is needed within and across biomes, succession stages and plant types, both under controlled and field conditions, while separating PSF effects from other drivers (e.g., herbivory, competition, disturbance) of plant abundance to tease apart the role of soil biota in causing patterns of plant rarity versus commonness.

Placing plant-soil feedbacks in the context of plant community growth

“…Because most PSF research continues to be performed on plant monocultures in greenhouse conditions, the extent to which PSFs affect plant communities in the field remains unclear (Crawford et al, 2019;Forero et al, 2019;Ke & Wan, 2020;Reinhart et al 2021). Our factorial experiment provided unusually comprehensive information about PSFs in the field.…”

“…3) while sub-dominant species demonstrated large positive and large negative PSF. This perspective may help explain why PSFs often show weak correlations with landscape abundance (Reinhart et al 2021, but see Mangan et al 2010;Kulmatiski et al 2017).…”

“…Yet, most PSF research has been performed using plant monocultures in greenhouse conditions Forero et al 2019). Recent work suggests that these greenhouse experiments provide little insight into plant growth in field communities (Forero et al 2019;Reinhart et al 2021). There remains, therefore, a need to better understand the role of PSF in plant communities in the field (Kulmatiski and Kardol 2008;Lekberg et al 2018).…”

Moderate plant–soil feedbacks have small effects on the biodiversity–productivity relationship: A field experiment

“…Yet, most PSF research has been performed using plant monocultures in greenhouse conditions (Forero et al., 2019 ; Kulmatiski et al., 2008 ). Recent work suggests that these greenhouse experiments provide little insight into plant growth in field communities (Forero et al., 2019 ; Reinhart et al., 2021 ). There remains, therefore, a need to better understand the role of PSF in plant communities in the field (Kulmatiski & Kardol, 2008 ; Lekberg et al, 2018 ).…”

“…Further, most PSF research has measured PSFs without explicitly testing the role of the PSFs in plant mixtures (Ke & Wan, 2020 ; Kulmatiski et al., 2012 ; van der Putten et al., 2013 ). As a result, it is not known whether PSFs affect species coexistence or community productivity or whether PSFs are overwhelmed by other factors related to plant growth such as competitive interactions, herbivory, or intrinsic growth rates (Heinze & Joshi, 2018 ; Kulmatiski et al., 2011 ; Lekberg et al, 2018 ; Reinhart et al., 2021 ).…”