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Improving methods to evaluate the impacts of plant invasions: lessons from 40 years of research.

Stricker KB, Hagan D, Flory SL - AoB Plants (2015)

Bottom Line: Different methods provide information at diverse spatial and temporal scales with varying levels of reliability.Most of the studies were temporally and spatially restricted with 51 % of studies lasting <1 year and almost half of all studies conducted in plots or mesocosms <1 m(2).To more effectively quantify invasion impacts, we argue that longer-term experimental research and more studies that use predictive modelling and evaluate impacts of invasions on ecosystem processes and fauna are needed.

View Article: PubMed Central - PubMed

Affiliation: Agronomy Department, University of Florida, Gainesville, FL 32611, USA.

No MeSH data available.


Examples of experimental methods to evaluate invasion impacts: (A) removal by hand, (B) treatment with prescribed fire, (C) addition of an invasive plant in a common garden and (D) addition of an invasive species in outdoor mesocosms under multiple shade treatments. All photos S.L. Flory.
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PLV028F1: Examples of experimental methods to evaluate invasion impacts: (A) removal by hand, (B) treatment with prescribed fire, (C) addition of an invasive plant in a common garden and (D) addition of an invasive species in outdoor mesocosms under multiple shade treatments. All photos S.L. Flory.

Mentions: Studies that use experimental approaches to evaluate the impacts of plant invasions include experimental removal (Fig. 1A and B) or addition (Fig. 1C and D) of the target species. Experimental removal studies indirectly indicate plant invasion impacts by evaluating how the community responds once the invasive species has been removed (e.g. Alvarez and Cushman 2002; Gratton and Denno 2005; Flory and Clay 2009; Spellman and Wurtz 2011). Removal of invasive plants can be accomplished with mechanical (pulling, mowing, string trimming, Fig. 1A) or chemical (pre- or post-emergent herbicide) treatments, biological control agents or by prescribed burning (Fig. 1B). The advantage of removal studies is that by experimentally removing the invasive plant it is relatively straightforward to interpret differences among invaded and experimentally treated plots. In addition, there are fewer ethical considerations than with experimental addition studies. However, although it may be possible to remove the invasive plant itself, there may be lasting (i.e. legacy) effects of the invasion on soil chemistry or microbial communities (Marchante et al. 2009), the response of the native community may be delayed, native species may respond to the disturbance caused by the removal of invasive plants, or other invasive plant species might colonize the site (Mack and Lonsdale 2002; Ogden and Rejmánek 2005; Mau-Crimmins 2007). Furthermore, the method used to remove the invasive plant may influence the native community response. For example, application of a grass-specific herbicide effectively removed an invasive grass and allowed native forbs and trees to return, whereas hand-weeding inhibited tree and fern recovery (Flory and Clay 2009). Given the potential difficulty in interpreting responses to experimental removal treatments, it was recently recommended to simultaneously establish plots where the invader is removed and at the same time to remove natives from uninvaded plots (Kumschick et al. 2015). Coupled with observations of invaded and uninvaded areas, such a design would allow for evaluation of possible disturbance effects associated with the removal treatments and inform the success of restoration efforts.Figure 1.


Improving methods to evaluate the impacts of plant invasions: lessons from 40 years of research.

Stricker KB, Hagan D, Flory SL - AoB Plants (2015)

Examples of experimental methods to evaluate invasion impacts: (A) removal by hand, (B) treatment with prescribed fire, (C) addition of an invasive plant in a common garden and (D) addition of an invasive species in outdoor mesocosms under multiple shade treatments. All photos S.L. Flory.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4418169&req=5

PLV028F1: Examples of experimental methods to evaluate invasion impacts: (A) removal by hand, (B) treatment with prescribed fire, (C) addition of an invasive plant in a common garden and (D) addition of an invasive species in outdoor mesocosms under multiple shade treatments. All photos S.L. Flory.
Mentions: Studies that use experimental approaches to evaluate the impacts of plant invasions include experimental removal (Fig. 1A and B) or addition (Fig. 1C and D) of the target species. Experimental removal studies indirectly indicate plant invasion impacts by evaluating how the community responds once the invasive species has been removed (e.g. Alvarez and Cushman 2002; Gratton and Denno 2005; Flory and Clay 2009; Spellman and Wurtz 2011). Removal of invasive plants can be accomplished with mechanical (pulling, mowing, string trimming, Fig. 1A) or chemical (pre- or post-emergent herbicide) treatments, biological control agents or by prescribed burning (Fig. 1B). The advantage of removal studies is that by experimentally removing the invasive plant it is relatively straightforward to interpret differences among invaded and experimentally treated plots. In addition, there are fewer ethical considerations than with experimental addition studies. However, although it may be possible to remove the invasive plant itself, there may be lasting (i.e. legacy) effects of the invasion on soil chemistry or microbial communities (Marchante et al. 2009), the response of the native community may be delayed, native species may respond to the disturbance caused by the removal of invasive plants, or other invasive plant species might colonize the site (Mack and Lonsdale 2002; Ogden and Rejmánek 2005; Mau-Crimmins 2007). Furthermore, the method used to remove the invasive plant may influence the native community response. For example, application of a grass-specific herbicide effectively removed an invasive grass and allowed native forbs and trees to return, whereas hand-weeding inhibited tree and fern recovery (Flory and Clay 2009). Given the potential difficulty in interpreting responses to experimental removal treatments, it was recently recommended to simultaneously establish plots where the invader is removed and at the same time to remove natives from uninvaded plots (Kumschick et al. 2015). Coupled with observations of invaded and uninvaded areas, such a design would allow for evaluation of possible disturbance effects associated with the removal treatments and inform the success of restoration efforts.Figure 1.

Bottom Line: Different methods provide information at diverse spatial and temporal scales with varying levels of reliability.Most of the studies were temporally and spatially restricted with 51 % of studies lasting <1 year and almost half of all studies conducted in plots or mesocosms <1 m(2).To more effectively quantify invasion impacts, we argue that longer-term experimental research and more studies that use predictive modelling and evaluate impacts of invasions on ecosystem processes and fauna are needed.

View Article: PubMed Central - PubMed

Affiliation: Agronomy Department, University of Florida, Gainesville, FL 32611, USA.

No MeSH data available.