CHAMPAIGN, Ill. – The role of the U.S. Army Engineer Research and Development Center (ERDC), Construction Engineering Research Laboratory (CERL), Threatened and Endangered Species (TES) program is to identify and understand areas of targeted endangered species management and conservation.
Why is this important? The presence of TES on military lands can result in military training restrictions, but effective management and conservation has the potential to substantially deconflict military training and endangered species mandates. In many cases, this presents a win-win scenario where endangered species thrive on installations while military operations maintain flexibility.
The Department of Defense (DoD) is responsible for over 30 million acres of land, and the DoD simultaneously balances military training requirements with careful stewardship of the nation’s ecosystems. This balancing act is particularly apparent on the Hawaiian Islands, where there are 11 military installations representing all services. Installation personnel in these locations are tasked with managing over 100 federally listed endangered species.
One of the CERL TES team’s research projects in Oahu, Hawaii, has uncovered the double-edged sword of non-native species for ecosystem functioning. Non-native species are often maligned for their negative impacts on ecosystems, but in Hawaii, where most native birds are extinct, non-native birds partially serve the roles of native species in seed dispersal of plants. However, non-native birds are also much more likely to disperse invasive plants than native plants, contributing to invasive plant spread.
The TES team’s most startling finding is that – although they documented over 4,000 interactions between plants and birds – they did not document a single interaction between a native bird and a native fruit. All interactions included at least one non-native partner. The majority of woody plants in Hawaii, including numerous endangered species that the U.S. Army manages, are adapted for seed dispersal by birds, but nearly all native frugivorous (fruit-eating) birds are extinct in Hawaii. The researchers’ work indicates that seed dispersal on Oahu is nearly entirely dependent on non-native birds.
Unfortunately, the team also found that non-native bird species, being much smaller than native bird communities, may only partially fill the role of native species. Research indicates that non-native birds are not dispersing large-seeded plant species, which has profound repercussions for the spread of invasive species and the conservation of native species.
The research initially started as a Strategic Environmental Research and Development Program project to examine the role of invasive species on seed dispersal in Hawaii. The project grew when the CERL team and their research partners realized that they could use the robust dataset compiled on seed dispersal to examine and evaluate ecological network structure and stability.
Consequently, the researchers received additional funding to explore seed dispersal networks through examination of the mechanistic underpinnings of interactions. This research led to analyses of network mechanisms, structure and robustness that have been detailed in numerous scientific publications, including in Proceedings of the National Academy of Sciences of the United States of America.
The CERL team’s research lays the groundwork for the inclusion of seed dispersal in endangered plant management in Hawaii. Seed dispersal is required for many plant species to successfully germinate, but little was known before these projects about seed dispersal mechanisms and limitations for dozens of Hawaii endangered plants. The results provide critical information on which plants are being dispersed, the birds dispersing them and the plants that will require further human intervention — e.g., hand sowing. This is particularly important because many of the endangered plant species the team studies are found exclusively or predominantly on military installations, highlighting the importance of effective Army land management for maintaining biodiversity.
All of these projects are linked under the Hawaii VINE (Vertebrate Introductions and Novel Ecosystems) project, in collaboration with Drs. Jeferson Vizentin-Bugoni (ERDC-CERL), J. Patrick Kelley (University of Wyoming), Jason Gleditsch (University of Illinois), Jeffrey Foster (Northern Arizona University), Donald Drake (University of Hawaii - Manoa), Amy Hruska (University of Hawaii - Manoa), Rebecca Wilcox (University of Wyoming), Samuel Case (University of Wyoming) and Corey Tarwater (University of Wyoming). To learn more about this research, visit https://m.facebook.com/hawaii.vine.project/.
For more information about the research in Oahu, HI., please visit the link: http://www.uwyo.edu/uw/news/2021/01/uw-researchers-find-nonnative-species-in-oahu-play-greater-role-in-seed-dispersal-networks.html