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Restoration of native plant communities in a H awaiian dry lowland ecosystem dominated by the invasive grass M egathyrsus maximus
Author(s) -
Ammondt Selita A.,
Litton Creighton M.,
Ellsworth Lisa M.,
Leary James K.
Publication year - 2013
Publication title -
applied vegetation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.096
H-Index - 64
eISSN - 1654-109X
pISSN - 1402-2001
DOI - 10.1111/j.1654-109x.2012.01208.x
Subject(s) - native plant , biology , invasive species , introduced species , biomass (ecology) , restoration ecology , perennial plant , sowing , ecosystem , agronomy , groundcover , botany , ecology
Questions How does a highly degraded H awaiian tropical dry lowland ecosystem dominated by the non‐native invasive M egathyrsus maximus (guinea grass) respond to different restoration treatments (three native species outplanting treatments; four native broadcast seed treatments)? What effect do restoration treatments have on invasive and native species groundcover, biomass and physiological activity, and volumetric soil water content? Location Waianae K ai F orest R eserve, I sland of O ahu, H awaii, USA . Methods The invasive grass M . maximus was suppressed by initial mowing and pre‐ and post‐planting herbicide applications. Native species were added in three outplant and four broadcast seed treatments in a complete randomized block design. Native species and M . maximus growth and ecophysiology, and volumetric soil water content were quantified for 8 mo following treatment establishment. Results Native species outplant survival ranged from 38% to 67%. Cover of M . maximus was significantly reduced in all outplant treatments compared with control and treated control (mowing and herbicide without native species additions), but did not differ across outplant treatments. Of the native species, D odonaea viscosa biomass was higher than C ordia subcordata , while other native species did not differ. Maximum photosynthetic rates ( A max ) did not differ across species in J uly. However, in A ugust (drier period), M . maximus exhibited lower A max than all native species except T . populnea , indicating adaptive dormancy during drought. Broadcast seeding with native species was not an effective restoration treatment, as field germination ranged from 0.5% to 2.3%. Conclusions Ecological restoration of highly invaded H awaiian tropical dry lowland ecosystems can be mediated through aggressive invasive species suppression and native species outplanting. Recommendations for restoration include initial removal of invasive grasses, adaptive suppression of grasses post‐outplanting, and utilization of diverse native species assemblages that are ecophysiologically adapted to local conditions and competitive with M . maximus .