Phenological niches and the future of invaded ecosystems with climate change
Wolkovich, E. M., & Cleland, E. E. (2014). Phenological niches and the future of invaded ecosystems with climate change. AoB Plants, 6, plu013. PDF.
Summary
Wolkovich & Cleland (2014) review how invasive plant phenology could create novel advantages with climate change. Invasive species are thought to establish and spread when competition from native species is low and extra resources (e.g., light, water, soil nutrients) are available. These times when native species competition is low could arise seasonally. For example, earlier green-up and later senescence relative to native communities have been observed in non-native plants. But, with climate change, this extended growing season could create a greater competitive advantage for invasive plants as conditions in the spring and fall become more conducive to plant growth. Additionally, earlier green-up in plants is correlated with 'weedier' traits, including smaller plants with smaller seeds and faster growth rates. Climate change is likely to favor species that can quickly take advantage of longer growing seasons by tracking temperature warming, a trait called 'phenological plasticity'. Several studies, including one long-term study near Boston, have observed high phenological plasticity in invasive plants. Therefore, invasive plants are poised to take advantage of the novel seasonal resources that climate change will provide.
Take home points
Invasive plants already tend to have longer growing seasons than native plants. Climate change will make these shoulder seasons more conducive to invasive plant growth.
Invasive plants tend to have higher phenological plasticity (i.e. their growth is more responsive to temperature) than native plants. Climate change will create an advantage for species that can green up earlier as temperature warms.
Management implications
Invasive plants are likely to be more responsive to climate than native species, and will advance their phenologies more quickly to track climate warming.
If invasive plants separate from native plants in terms of their green-up (earlier) and senescence (later), this could expand the seasonal windows of effective chemical or mechanical treatments.
Research Needs
It is unclear to me from this review how robust the supporting empirical evidence is for greater phenological plasticity amongst invasive plants as well as for a longer fall growing season. The number of studies cited is underwhelming. Are invasive plants more phenologically plastic than non-native plants? Would need to control for phylogeny. Does information about plasticity exist?
There is some interesting discussion in this paper of different climate drivers of phenology in temperate vs. semi-arid vs. grassland studies. Seems like geography matters a fair bit.
Keywords
Shifting Seasons; Competitiveness; Review; Invasive Plant; Risk Assessment