Havran, J. Christopher , Brown, K.J. , Ballard, H. E. .
Habitat characterization of the Hawaiian Violets: Comparison of Violet habitats on Kauai, Oahu, Molokai, Maui, and Lanai.
The Hawaiian Violets (Viola, Violaceae) are a monophyletic lineage of nine species that have undergone an adaptive radiation into four habitat regimes across the Hawaiian archipelago: dry forest, mesic forest, cloud forest, and montane bog. Violet species growing in analogous habitats on different islands converge in growth form and leaf morphology, but very little is known about conservation of quantifiable ecological parameters in habitats occupied by morphologically similar species, or the extent to which these parameters overlap across habitats occupied by different species. From June 2003 to February 2007, the microhabitat parameters (canopy openness, air temperature, relative humidity, Volumetric Water Content (VWC), and soil nutrients) of Violet habitats on Kauai, Oahu, Molokai, Maui, and Lanai were measured and analyzed through Discriminate Analysis, MANOVA, and One-Way ANOVA followed by a Tukey-Kramer Multiple Comparisons Test. Multivariate analysis of edaphic and climate factors separate the habitats into two groups: middle-elevation (dry forests and mesic forests) and high-elevation (cloud forest and montane bog). Middle-elevation habitats have significantly lower levels of organic carbon (7% vs. 50% OC) and higher pH than high-elevation habitats. High-elevation habitats (cloud forest and montane bog) are found in close proximity, and their inclusive species grow within meters of one another. Despite their proximity, the cloud forest and montane bog are separated by a gradient of VWC (50-60% VWC in cloud forests vs 80-100% in bogs). Ecologically-analogous high-elevation habitats on different islands possess similar ranges of VWC, temperature, and canopy openness but differ significantly in soil nutrients (pH, %N, Mg, and P). The differences in soil nutrient values on different islands are explained by the chronosequence, and agree with earlier comparative studies of the Hawaiian Islands. This study lays the groundwork for future studies of the convergence of physiological and genetic mechanisms under similar habitat regimes in the Hawaiian archipelago.
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1 - Ohio University, Department of Environmental and Plant Biology, Porter 315, Athens, OH, 45701, U.S.A.
2 - Ohio University, Department of Environmental & Plant Biology, Porter Hall, Richland Avenue, Athens, Ohio, 45701-2979, USA
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM