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A pathogen arriving on a host typically encounters a diverse community of microbes that can shape priority effects, other within-host interactions and infection outcomes. In plants, environmental nutrients can drive trade-offs between host growth and defence and can mediate interactions between co-infecting pathogens. Nutrients may thus alter the outcome of pathogen priority effects for the host, but this possibility has received little experimental investigation. To disentangle the relationship between nutrient availability and co-infection dynamics, we factorially manipulated the nutrient availability and order of arrival of two foliar fungal pathogens (Rhizoctonia solaniandColletotrichum cereale) on the grass tall fescue (Lolium arundinaceum) and tracked disease outcomes. Nutrient addition did not influence infection rates, infection severity or plant biomass.Colletotrichum cerealefacilitatedR. solani, increasing its infection rate regardless of their order of inoculation. Additionally, simultaneous andC. cereale-first inoculations decreased plant growth and—in plants that did not receive nutrient addition—increased leaf nitrogen concentrations compared to uninoculated plants. These effects were partially, but not completely, explained by the duration and severity of pathogen infections. This study highlights the importance of understanding the intricate associations between the order of pathogen arrival, host nutrient availability and host defence to better predict infection outcomes.
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Priority effects and ecological restoration
Priority effects refer to the order or timing of species arrival, including how species that arrive early at a site either positively or negatively affect establishment, growth, or reproduction of species that arrive later. Despite the clear implications of priority effects for ecological restoration, there have been no reviews of how and where priority effects have been studied and the extent to which findings can be applied to restoration. Here, we systematically review the literature on priority effects by (1) synthesizing information from papers that compared simultaneous and nonsimultaneous planting or sowing; (2) discussing the mechanisms through which priority effects operate, (3) considering how these mechanisms might be manipulated to achieve restoration goals; and (4) highlighting future research needed to improve the use of priority effects in restoration. In a term‐targeted search, we found 43 studies that experimentally manipulated the order of arrival of different species. Overall, these concluded that even small delays in arrival time, as opposed to simultaneous arrival of species, can promote differences in subsequent community composition as well as ecosystem functions. There were very few studies on the long‐term stability of these priority effects, and the majority were conducted in temperate grasslands. Our findings suggest that creating alternative vegetation states via priority treatments is a promising avenue for restoration. However, for the concept to be best operationalized for restoration, we need research in more ecosystems that are priorities for restoration, and treatments that are followed over extended time periods.
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- Award ID(s):
- 1757351
- PAR ID:
- 10454304
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Restoration Ecology
- Volume:
- 29
- Issue:
- 1
- ISSN:
- 1061-2971
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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