Skip to Main Content
Remote analysis of biological invasion and the impact of enemy releaseAuthor(s): James R. Kellner; Gregory P. Asner; Kealoha M. Kinney; Scott R. Loarie; David E. Knapp; Ty Kennedy-Bowdoin; Erin J. Questad; Susan Cordell; Jarrod M. Thaxton
Source: Ecological Applications 21(6): 2094-2104
Publication Series: Scientific Journal (JRNL)
View PDF (439.98 KB)
DescriptionEscape from natural enemies is a widely held generalization for the success of exotic plants. We conducted a large-scale experiment in Hawaii (USA) to quantify impacts of ungulate removal on plant growth and performance, and to test whether elimination of an exotic generalist herbivore facilitated exotic success. Assessment of impacted and control sites before and after ungulate exclusion using airborne imaging spectroscopy and LiDAR, time series satellite observations, and ground-based field studies over nine years indicated that removal of generalist herbivores facilitated exotic success, but the abundance of native species was unchanged. Vegetation cover <1 m in height increased in ungulate-free areas from 48.7% ± 1.5% to 74.3% ± 1.8% over 8.4 years, corresponding to an annualized growth rate of λ = 1.05 ± 0.01 yr−1 (median ± SD). Most of the change was attributable to exotic plant species, which increased from 24.4% ± 1.4% to 49.1% ± 2.0%, (λ = 1.08 ± 0.01 yr−1). Native plants experienced no significant change in cover (23.0% ± 1.3% to 24.2% ± 1.8%, λ = 1.01 ± 0.01 yr−1). Time series of satellite phenology were indistinguishable between the treatment and a 3.0-km2 control site for four years prior to ungulate removal, but they diverged immediately following exclusion of ungulates. Comparison of monthly EVI means before and after ungulate exclusion and between the managed and control areas indicates that EVI strongly increased in the managed area after ungulate exclusion. Field studies and airborne analyses show that the dominant invader was Senecio madagascariensis, an invasive annual forb that increased from <0.01% to 14.7% fractional cover in ungulate-free areas (λ = 1.89 ± 0.34 yr−1), but which was nearly absent from the control site. A combination of canopy LAI, water, and fractional cover were expressed in satellite EVI time series and indicate that the invaded region maintained greenness during drought conditions. These findings demonstrate that enemy release from generalist herbivores can facilitate exotic success and suggest a plausible mechanism by which invasion occurred. They also show how novel remote-sensing technology can be integrated with conservation and management to help address exotic plant invasions.
- You may send email to firstname.lastname@example.org to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationKellner, James R.; Asner, Gregory P.; Kinney, Kealoha M.; Loarie, Scott R.; Knapp, David E.; Kennedy-Bowdoin, Ty; Questad, Erin J.; Cordell, Susan; Thaxton, Jarrod M. 2011. Remote analysis of biological invasion and the impact of enemy release. Ecological Applications 21(6): 2094-2104. doi:10.1890/10-0859.1
Keywordsexotic, functional trait, Hawaii, imaging spectroscopy, invasive species, LiDAR, MODIS, remote sensing, resource-use efficiency, tropical dry forest
- Host range of Secusio extensa (Lepidoptera: Arctiidae), and potential for biological control of Senecio madagascariensis (Asteraceae)
- Assessing the effectiveness of seeding and fertilization treatments for reducing erosion potential following severe wildfires
- Effects of post-harvest treatments on high-elevation forests in the North Cascade Range, Washington.
XML: View XML