Using indicators of land-use development intensity to assess the condition of coastal wetlands in Hawai‘i

• Published in: Landscape ecology 2014, Vol.29 (3), p.517-528
• Main Authors: Margriter, Sandra C, Bruland, Gregory L, Kudray, Gregory M, Lepczyk, Christopher A
• Format: Article
• Language: English
• Subjects: Biomedical and Life Sciences; Ecology; Environmental Management; forests; land use; Landscape Ecology; Landscape/Regional and Urban Planning; landscapes; Life Sciences; Nature Conservation; nutrient content; plant tissues; rapid methods; Research Article; soil water; surface water; Sustainable Development; water quality; watersheds; wetlands
• ISSN: 0921-2973; 1572-9761
• DOI: 10.1007/s10980-013-9985-7

Although wetland condition assessment procedures have been developed, validated, and calibrated in the continental United States, they have not yet been fully developed or field-tested for wetlands in Hawai‘i. In order to address the need for comprehensive assessment methods for Hawaiian coastal wetlands, our research compared three indicators of landscape condition (landscape development intensity, road density, and forest cover) with wetland condition as measured by rapid assessment methods (RAM) and detailed field data collected on soil and water quality. We predicted that wetlands located in the least developed landscapes would have more nutrient rich soils, yet lower nutrient levels in the surface water, and would receive the highest rapid assessment scores. The hypotheses of our study were generally supported. However, while the correlations between landscape variables and δ¹⁵N isotopes and CRAM scores were relatively strong, the correlations between the landscape indicators and the other Level II and III field indicators were not very strong. These results suggest that further calibration and refinement of metrics is needed in order to more accurately assess the condition of Hawaiian coastal wetlands. A more detailed land use map, in addition to more comprehensive assessments of wetland water quality and biotic integrity would likely improve the relationships between indicators of landscape condition and wetland condition. Nonetheless, our research demonstrated that landscape analysis at larger scales (1,000 m buffers and watersheds) could provide managers with valuable information on how regional stressors may be affecting wetland water quality (measured as δ¹⁵N in plant tissue) as well as overall wetland condition (RAM scores).