Weller, Stephen G. , Cabin, Robert , Lorence, David H , Perlman, Steven , Wood, Kenneth R. , Flynn, Timothy , Sakai, Ann K. .
Alternative states in an endangered, diverse mesic forest in Hawaii: interactions between ungulate removal and alien plant invasions, and the potential for habitat restoration.
Restoration of native ecosystems by natural successional processes after removal of perturbations may not be feasible for most systems. Controlling major ecological threats such as non-native ungulates is often a critical first step towards restoring native communities but past degradation, interactions with alien species, and abiotic features may create conditions requiring additional intervention to ensure effective conservation of these remnant ecosystems. The highly threatened, diverse mesic forest of Mahanaloa Gulch, located on western Kauai in the Hawaiian Islands, is characterized by high endemism, with 18 federally-listed endangered species, 14 of which are endemic to Kauai. Fenced plots in Mahanaloa Gulch were monitored from 1998 to 2005 to determine the effects of ungulate removal on native and alien plant species. Relative to unfenced control plots, germination of seedlings and frequency of understory species of both native and alien species increased in the fenced plots. Density of both native and alien canopy and understory species declined more in unfenced than fenced plots, but density of native species declined more than alien species density in both fenced and unfenced plots. In fenced plots, the frequency of larger alien woody species and cover of an alien, mat-forming fern species increased over time, indicating that fencing may encourage alien species that could interfere with regeneration of native species. Conservation of native Hawaiian forests will require both ungulate exclusion and additional management such as removal of alien plant species with especially detrimental effects on native species. Proactive restoration programs will be essential for native species without natural sources of propagules. As the effects of invasive species continue to escalate, continental ecosystems lacking high endemism may also require intense manipulation to preserve biodiversity.
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1 - University of California Irvine, Department of Ecology & Evolutionary Biology, 321 Steinhaus Hall, Irvine, California, 92697-2525, USA
2 - Brevard College, Brevard, North Carolina, 28712, U.S.A.
3 - National Tropical Botanical Garden, 3530 Papalina Road, Kalaheo, Kauai, Hawaii, 96741, USA
4 - National Tropical Botanical Garden, 3530 Papalina Road, Kalaheo, Kauai, Hawaii, 96741, USA
alien plant species
diverse mesic forest
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Alpine B/Snowbird Center
Date: Tuesday, July 28th, 2009
Time: 11:15 AM