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Abstract Historically high cattle stocking rates and extreme drought contribute to the degradation of rangelands in southwestern United States. To mitigate erosion and provide forage for cattle in this region, land managers seededEragrostis lehmannianaNees (Lehmann lovegrass), a warm‐season perennial grass from South Africa in the 1930s. Although valuable for cattle forage,E. lehmannianais a strong competitor, responds well to ecological disturbance, and has become invasive. The purpose of this study was to quantify the plant–soil feedbacks (PSF) ofE. lehmannianaon itself and on nativeBouteloua eriopoda(black grama) under different soil moisture, soil fertility, and plant competition conditions. We conducted a two‐phase PSF greenhouse study, incorporating fertiliser and watering treatments, and a replacement series competition study. PSF and competition were evaluated using biomass log–response ratio and relative yield, respectively. Further, we developed a new method to quantitatively evaluate the impacts of treatments on competition within the replacement series study. PSF were mostly neutral or positive for bothB. eriopodaandE. lehmanniana, andE.lehmannianainoculum did not create negative PSF. Inoculation withE. lehmannianaand subsequent fertilisation resulted in the strongest PSF; a positive PSF onB. eriopodaunder both drought and normal watering. Within the competition study, fertiliser addition was the most influential factor, often resulting inE. lehmannianaoutcompetingB. eriopoda. This research helps elucidateE. lehmannianainteractions with nativeB. eriopoda, suggesting that inE. lehmannianainvaded areas, legacy effects should not hinderB. eriopodarestoration. Finally, our new method for analysing replacement series competition experiments can help elucidate treatment effects in future studies.
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Invasive plant benefits a native plant through plant-soil feedback but remains the superior competitor
Plant soil feedback (PSF) occurs when a plant modifies soil biotic properties and those changes in turn influence plant growth, survival or reproduction. These feedback effects are not well understood as mechanisms for invasive plant species. Eragrostis lehmanniana is an invasive species that has extensively colonized the southwest US. To address how PSFs may affect E. lehmanniana invasion and native Bouteloua gracilis growth, soil inoculant from four sites of known invasion age at the Appleton-Whittell Audubon Research Ranch in Sonoita, AZ were used in a PSF greenhouse study, incorporating a replacement series design. The purpose of this research was to evaluate PSF conspecific and heterospecific effects and competition outcomes between the invasive E. lehmanniana and a native forage grass, Bouteloua gracilis . Eragrostis lehmanniana PSFs were beneficial to B. gracilis if developed in previously invaded soil. Plant-soil feedback contributed to competitive suppression of B. gracilis only in the highest ratio of E. lehmanniana to B. gracilis . Plant-soil feedback did not provide an advantage to E. lehmanniana in competitive interactions with B. gracilis at low competition levels but were advantageous to E. lehmanniana at the highest competition ratio, indicating a possible density-dependent effect. Despite being beneficial to B. gracilis under many conditions, E. lehmanniana was the superior competitor.
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- PAR ID:
- 10298482
- Date Published:
- Journal Name:
- NeoBiota
- Volume:
- 64
- ISSN:
- 1619-0033
- Page Range / eLocation ID:
- 119 to 136
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.3897/neobiota.64.57746
