The role of plant–soil feedbacks in driving native-species recovery

Abstract

The impacts of exotic plants on soil nutrient cycling are often hypothesized to reinforce their dominance, but this mechanism is rarely tested, especially in relation to other ecological factors. In this manuscript we evaluate the influence of biogeochemically mediated plant-soil feedbacks on native shrub recovery in an invaded island ecosystem. The introduction of exotic grasses and grazing to Santa Cruz Island, California, USA, converted native shrublands (dominated by Artemisia californica and Eriogonum arborescens) into exotic-dominated grasslands (dominated by Avena barbata) over a century ago, altering nutrient-cycling regimes. To test the hypothesis that exotic grass impacts on soils alter reestablishment of native plants, we implemented a field-based soil transplant experiment in three years that varied widely in rainfall. Our results showed that growth of Avena and Artemisia seedlings was greater on soils influenced by their heterospecific competitor. Theory suggests that the resulting plant-soil feedback should facilitate the recovery of Artemisia in grasslands, although four years of monitoring showed no such recovery, despite ample seed rain. By contrast, we found that species effects on soils lead to weak to negligible feedbacks for Eriogonum arborescens, yet this shrub readily colonized the grasslands. Thus, plant-soil feedbacks quantified under natural climate and competitive conditions did not match native-plant recovery patterns. We also found that feedbacks changed with climate and competition regimes, and that these latter factors generally had stronger effects on seedling growth than species effects on soils. We conclude that even when plant-soil feedbacks influence the balance between native and exotic species, their influence may be small relative to other ecological processes.

Weak conspecific feedbacks and exotic dominance in a species-rich savannah

“…The strength of this effect will ultimately depend on the relative importance of other limiting factors that can influence abundance and persistence, such as competition, dispersal limitation and herbivory [2,13]. All of these factors have been shown to constrain native plant performance in this system [58 -61], such that the net strength of the conspecific feedbacks could be relatively weak.…”

The Role of Plants in the Effects of Global Change on Nutrient Availability and Stoichiometry in the Plant-Soil System

“…Invasion can further interact with other drivers of global change such as N deposition, as discussed above. Moreover, some studies have reported that the effects of plant invasion on soil facilitate further invasion by the initial invasive species or by other species (Allison and Vitousek, 2004;Sharma and Raghubanshi, 2009), although not all studies provide clear results on this topic (Yelenik and Levine, 2011). Thus, alien success in nutrient-rich soils is related to higher growth rates, low C-N and C-P ratios, fast plasticity in resource acquisition capacity and high reproductive investment; in nutrient-poor soils, high invasive success is related to conservative use of resources including nutrients.…”

Below‐ground opportunities in vegetation science

“…Invasion success has also been considered in the light of plant-soil feedbacks (Packer & Clay 2000;Klironomos 2002;Bever et al 2010;Yelenik & Levine 2011;Suding et al 2013). The potential complexity of these feedbacks is shown in the case of the invasive nitrogen (N)-fixing tree Robinia pseudoacacia L. (Callaway et al 2011).…”