“Novel Network Connections for Seed Dispersal in Hawaii” by Dr. Jeffrey Foster

This project investigated seed dispersal by non-native birds in Hawaii based on SERDP’s focus on the recovery of ecological processes impacted by non-native invasive species in the Pacific Islands. The Hawaiian Islands are both the extinction and invasive species capitals of the world. The result has been that Hawaiian ecosystems fundamentally changed in form and became replete with a mix of introduced and native species. Most native Hawaiian plant species are bird-dispersed, yet no native avian dispersers remain in most Hawaiian ecosystems. Thus, ecosystem functioning will only be maintained by the handful of non-native vertebrate dispersers remaining. We found that introduced species, both birds and plants, quickly integrated into these novel networks. These species developed complex network structures with non-native plants playing a primary role in these communities making restoration of native ecosystems more challenging than previously thought. Moreover, Hawaiian seed dispersal networks were similar to other communities worldwide suggesting that interaction patterns among species may be highly conserved, regardless of species identity and environment. The proposed research provided the Department of Defense with the essential tools for managing and maintaining native plant communities in Hawaii and other Pacific Islands, while recognizing that non-native invasions provide substantial obstacles to conservation on military lands.
 

“Pollination Services in a Hawaiian Dry Forst Ecosystem Impacted by Invasive Predators” by Dr. Christina Liang

Non-native species can disrupt native ecosystem processes. Such impacts are particularly acute for oceanic islands which are well known for high endemism and unique biological diversity but are also particularly susceptible to species invasions. This project examined the effects of non-native invasive predators (NIPs) on pollination function and native plant reproduction in a tropical dryland ecosystem in Hawaii and supports SERDP’s effort to inform conservation actions driven by good stewardship principles and compliance with federal regulations. We combined field observation, experimental manipulation, and laboratory analysis to examine interactions between eight focal native plant species, insect pollinators (both native and non-native) and NIPs. Plant species included four endangered plant species and four common plant species, which together have a diversity of floral traits to maximize the potential diversity of insect pollinators that were attracted to our study plants overall. This presentation described our flower visitation observations, pollination experiments, predator diet analyses, and experimental removal of NIPs to assess pollination of plant species in the increasingly threatened tropical dry forest ecosystem.

Dr. Jeffrey Foster is an Associate Professor at Northern Arizona University in Flagstaff, Arizona. He works broadly across ecology and evolutionary biology, including research on birds, bats, and pathogens. Several of his primary field sites are in the Hawaiian Islands where he has worked since 1997 on seed dispersal, avian demography and disease. Dr. Foster has published more than 90 peer-reviewed papers and book chapters. He received a bachelor’s degree in biology from Northwestern University, Evanston, Illinois and a doctoral degree in ecology and evolutionary biology from the University of Illinois, Urbana-Champaign.

Dr. Christina Liang is a Research Ecologist with the United States Department of Agriculture Forest Service, Pacific Southwest Research Station in Hilo, Hawaii. Her current research integrates population, community, and landscape ecological and genetic-ecological approaches to expand knowledge of biotic responses to environmental conditions and changes, with applications for species-to-ecosystem conservation. Dr. Liang has served as a principal investigator on several projects investigating the ecology and conservation of endemic species and native ecosystems in Hawaii and California, particularly in response to environmental changes such as non-native invasive species, land management activities and changing climate conditions. She earned bachelor’s degrees in integrative biology and in conservation and resource studies from the University of California at Berkeley, a master’s degree in biology from the University of Michigan at Ann Arbor and a doctoral degree in ecology from the University of California at Davis.