Seasonal priority effects: implications for invasion and restoration in a semi-arid system

Wainwright, Claire E., Wolkovich, Elizabeth M. and Cleland, Elsa E. (2012) Seasonal priority effects: implications for invasion and restoration in a semi-arid system. Journal of Applied Ecology, 49 1: 234-241. doi:10.1111/j.1365-2664.2011.02088.x

Author Wainwright, Claire E.
Wolkovich, Elizabeth M.
Cleland, Elsa E.
Title Seasonal priority effects: implications for invasion and restoration in a semi-arid system
Journal name Journal of Applied Ecology   Check publisher's open access policy
ISSN 0021-8901
Publication date 2012-02
Sub-type Article (original research)
DOI 10.1111/j.1365-2664.2011.02088.x
Open Access Status Not yet assessed
Volume 49
Issue 1
Start page 234
End page 241
Total pages 8
Place of publication Oxford, United Kingdom
Publisher Wiley-Blackwell Publishing
Language eng
Formatted abstract
1. The timing of seasonal activity (i.e. phenology) may play an important role in plant invasions. In ecosystems characterized by seasonal rainfall, early-active exotic species may pre-empt resources and attain competitive dominance via a seasonal ‘priority advantage’. Exotic annual grasses in California are often active earlier than native species, potentially because they possess greater germination plasticity. While these problematic invaders may usually benefit from having early phenology, their flexible germination cues might be manipulated as a restoration strategy to germinate seeds far in advance of favourable growing conditions, leading to a ‘priority disadvantage’.

2. We manipulated the start of the growing season in an invaded California coastal sage scrub community characterized by a Mediterranean-type climate to (i) identify whether early-season phenology confers a performance advantage and (ii) test whether rainfall timing could be manipulated to favour native species. We compared the performance of seeded native and exotic focal species under ambient rainfall timing (winter rains) vs. with a pre-growing season (late-summer) watering event.

3. Under ambient rainfall timing, exotic annual grasses and forbs germinated earlier and reached higher levels of abundance than native species, consistent with a seasonal priority advantage. Many exotic annual grasses germinated with pre-season watering, but none survived until the onset of natural rains. Observations suggest that early-germinating seedlings suffered mortality via herbivory. The watering pulse thus depleted the exotic seedbank, fewer exotic individuals germinated with winter rains, and exotic species attained lower abundance than under the natural rainfall timing.

4. Native species, whether annual or perennial, did not germinate with the pre-season watering pulse, suggesting they may have more constrained germination cues than the exotic species.

5. Synthesis and applications. Our results suggest that phenology is an important factor influencing invasion success, and that this could be manipulated to favour native species. Manipulation of the start of the growing season, for example through a pre-growing season watering event, could be a successful restoration strategy for native species in some ecosystems.
Keyword Community assembly
Community ecology
Ecological restoration
Exotic annual grass
Invasive species
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biological Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 33 times in Thomson Reuters Web of Science Article | Citations
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Created: Mon, 17 Aug 2015, 14:08:23 EST by Claire Wainwright on behalf of School of Biological Sciences