DISTRIBUTION AND ABUNDANCE OF *CIBOTIUM*, *ANGIOPTERIS*, AND *SPHAEROPTERIS* TREE FERN SPECIES IN THE KO’OLAU MOUNTAINS ON O’AHU: IMPLICATIONS FOR CONSERVATION LAND MANAGEMENT IN THE CONTEXT OF WATERSHED PROTECTION
Kraft, Victoria C 1
1 University of Colorado, Geography & Environmental Studies
An outstanding problem in Hawai’i is invasive species of tree ferns that can outcompete native species, with unknown but potentially large consequences on ecosystem function. My research project involves ground survey observations of the three endemic Cibotium and non-native Angiopteris evecta and Sphaeropteris cooperi tree fern species in the Central and Southern Ko’olau Mountain Range on O’ahu, where Ko’olau Mountain Watershed Partnership (KMWP) manages for invasive species control and native forest preservation with focuses on water resources (Figures 1 & 2). Research objectives were to determine whether spatial patterns could be detected for each species, including density as a function of distance from source areas and elevation. Additionally, fill-based map results will be used to ground-truth KMWP aerial imagery. These objectives will immediately serve land managers for determining the most threatened native forest, and can be useful in the future as comparative data as we expect species distributions to change with changing climate conditions in the future. Vascular plants such as ferns play a significant role in the evolution of forest ecosystems, providing water and nutrient infiltration to the soil. The endemic tree ferns of the genus Cibotium(Cibotiaceae) are thought to be keystone species (Durand and Goldstein 2001), meaning they are ecologically important in the forests where they occur, in this instance, the sub canopy layer. The purpose of this survey fieldwork has been to overcome some of the current limitations existing in the study of Cibotiumdistribution and abundance on the Hawaiian Islands. Collaborative work with KMWP has potential for achieving strategies that meet watershed management goals and activities.
[Keywords: ferns and lycophytes, vascular plants, Cibotium, endemism, native species, Angiopteris evecta, Sphaeropteris cooperi, non-native alien species, naturalized taxa, invasive species, ground-truth, baseline data, conservation management, slope stability, soil moisture, habitat restoration, climate change, watershed protection]
Arcand, N. N. and T. A. Ranker. 2008. Conservation biology. Pp. 257–283 in T. A. Ranker and C. H. Haufler (eds), Biology and Evolution of Ferns and Lycophytes. Cambridge University Press, Cambridge.
Durand, L. Z., & Goldstein, G. (2001a). Growth, leaf characteristics, and spore production in native and invasive tree ferns in Hawaii. American Fern Journal, 91(1), 25-35.
"O'ahu Watershed Information Maps." State of Hawai'i Department of Land and Natural Resources. Web. 13 Mar. 2012.