UH Hilo Center for Maunakea Stewardship - Research Library

Changes in Mauna Kea Dry Forest Structure 2000-2014

Author:
Brinck, Kevin, Banko, Paul C.
Title:
Changes in Mauna Kea Dry Forest Structure 2000-2014
Periodical:
Hawaii Cooperative Studies Unit Technical Report
Year:
2014
Pages:
16
Subject:
Palila Birds habitat Mamane Sophora chrysophylla Mauna Kea volcano
Summary:
Changes in the structure of the subalpine vegetation of Palila Critical Habitat on the southwestern slope of Mauna Kea Volcano, Hawaii, were analyzed using 12 metrics of change in mamane (Sophora chrysophylla) and naio (Myoporum sandwicense) trees surveyed on plots in 2000 and 2014. These two dominant species were analyzed separately, and changes in their structure indicated changes in the forest’s health. There was a significant in crease in mamane minimum crown height (indicating a higher ungulate “browse line”), canopy area , canopy volume, percentage of trees with ungulate damage, and percentage of dead trees. No significant changes were observed in mamane maximum crown height, proportion of plots with trees, sapling density, proportion of plots with saplings, or the height distribution of trees. The only significant positive change was for māmane tree density. Significantly negative changes were observed for naio minimum crown height, tree height, canopy area, canopy volume, and percentage of dead trees. No significant changes were observed in naio tree density, proportion of plots with trees, proportion of plots with saplings, or percentage of trees with ungulate damage. Significantly positive changes were observed in naio sapling density and the height distribution of trees. There was also a significant increase in the proportion of māmane vs. naio trees in the survey area. The survey methods did not allow us to distinguish among potential factors driving these changes for metrics other than the percentage of trees with ungulate damage. Continued ungulate browsing and prolonged drought are likely the factors contributing most to the observed changes in vegetation, but tree disease or insect infestation of mamane, or naio, and competition from alien grasses and other weeds could also be causing or exacerbating the impacts to the forest. Although mamane tree density has increased since 2000, this study also demonstrates that efforts by managers to remove sheep (Ovis spp.) from Palila Critical Habitat have not overcome the ability of sheep to continue to damage mamane trees and impede restoration of the vegetation
URL:
http://hdl.handle.net/10790/2610
Date:
September 2014
Collection:
Monographs