Restoration of native plant communities in a Hawaiian dry lowland ecosystem dominated by the invasive grass Megathyrsus maximus.
A study was conducted to evaluate the response of a highly degraded Hawaiian tropical dry lowland ecosystem dominated by the non-native invasive Megathyrsus maximus [Panicum maximum] (guinea grass) to different restoration treatments (3 native species outplanting treatments and 4 native broadcast seed treatments) and to determine the effect of restoration treatments on invasive and native species groundcover, biomass and physiological activity, and volumetric soil water content. 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, Dodonaea viscosa biomass was higher than Cordia subcordata, while other native species did not differ. Maximum photosynthetic rates (Amax) did not differ across species in July. However, in August (drier period), M. maximus exhibited lower Amax 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%.