Shifting Limitations to Restoration across Dryland Ecosystems in Hawai?i

Hawaiian dryland ecosystems are important for global biodiversity conservation and contain numerous species threatened with extinction. Over the past century, wildfire frequency size have increased dramatically because of invasion by fire-promoting non-native invasive species, greatly threatening these ecosystems. Native restoration is a tool that can disrupt cycle fire in lowland dry forest communities, but prescriptions not been studied systematically other plant communities. We examined three communities (a high-productivity Diospyros sandwicensis Metrosideros polymorpha (HP), moderate-productivity Myoporum sandwicense Sophora chrysophylla forest/woodland (MP), low-productivity Dodonaea viscosa shrubland (LP)), using community-assembly framework to understand abiotic biotic constraints establishment growth each community. Because active methods often needed, at both high low levels productivity, we also treatments outcomes across sites, which spanned gradient rainfall substrate age. At site, used same factorial field experiment factors: habitat quality (high or low), weed control (yes no), addition (none, seeding, outplanting). Outplants (cohort 1) seeds were added winter 2009–2010, outplants again March 2011 2). Dispersal limitation was apparent LP HP observed MP had, overall, greater native diversity abundance. Outplant survival high-quality habitats likely due reduced stress. Invasive found abundance certain types microsites suggesting shade topography be plan weed-control activities. Overall, improved high- less so moderately productive site. Weed removal outplanting effective could increase Active lower priority invaded, capability maintain ecosystem state.