The loss and fragmentation of habitat is a primary cause of species extinction and loss of biodiversity. However, there are few studies of the long-term effects of a direct experiment in which habitat has been fragmented at the large spatial scales that typify the effects of land use on the landscape; such experiments provide direct tests of the mechanisms that are thought to make species more or less tolerant of habitat fragmentation. Short-term responses to experimental habitat fragmentation are more commonly documented, but these may be transient and so may not predict fates of species in the longer term. How many species that initially decline eventually go extinct? Do species that do not respond initially to habitat fragmentation go extinct in the longer term? This project will answer these questions in the Wog Wog fragmentation experiment (Australia), the longest running large-scale fragmentation experiment in temperate forest. Existing data from the first five years of the experiment will be combined with a matching series of new data to be collected now, 23-26 years after fragmentation, to determine whether the initial transient dynamics of beetle species predict their fates in the long term and to test which characteristics predict vulnerability or robustness to environmental habitat change.
Habitat loss and fragmentation continue at an accelerating rate and account for most biodiversity loss. Understanding their roles as drivers of extinction is of increasing importance to conservation and land management. The long-running, large-scale Wog Wog experiment provides a unique opportunity to understand why and how species go extinct, and which species are most at risk. A technician, a graduate student, and six undergraduates will receive interdisciplinary training in biology and mathematics through participation in this project, and outreach materials will be developed for high school students.
A. Summary aims This grant was to resurrect the Wog Wog habitat fragmentation experiment in Australia to examine long term trends in extinction of beetles in relation to their short term responses and traits. Now spanning 27 years, the Wog Wog experiment is the longest running fragmentation experiment in temperate forest. Experiments provide the strongest inferential framework in which to understand the dynamics of populations, communities, and ecosystems in response to habitat fragmentation. Experiments of large spatial and long temporal scale are rare and difficult but are needed to disentangle the different factors contributing to ecological change in fragmented landscapes, which include many unknown historical factors in non-experimental systems. Frequently, experimental studies have documented the decline of species towards extinction immediately following fragmentation. However, many existing studies have not gone beyond short term, possibly transient, dynamics to determine the fate of declining species in the longer term. Our aim was to test whether the long term fate of hundreds of beetle species in the Wog Wog experiment can be predicted from existing short term data (up to 5 years post fragmentation) together with data on species traits collected from specimens or the literature, such as dispersal ability and body size. B. Results and accomplishments: intellectual merit The Wog Wog experiment is one of just a handful of long-term, large scale habitat fragmentation experiments globally. The scientific value of these experiments is increasingly recognized as many of them enter their third and fourth decades. Basic questions about extinction still plague the field of ecology, and the fragmentation experiments continue to provide the best setting to study extinction experimentally, outside of micro/mesocosms and the laboratory. Therefore, bringing the Wog Wog experiment out of retirement, in collaboration with CSIRO, has been a major achievement of this grant. To this end we have: 1) gained access to the experiment, 2) recovered and curated a range of historic data, including abiotic data, vertebrates, invertebrates, and plants, 3) exactly reestablished all 188 historic sampling sites, and added environmental sensors at each site, 4) collected four years of invertebrate data (three seasons per year, 12 sample occasions in total), 5) processed sorted and identified the speciose beetle fauna to species and matched beetle species with an historic reference collection for 410 species (13,012 individuals) for the first two years of data collected. This project was structured around two overarching questions: Question 1: Do the short-term dynamics of beetle species through 5 years post experimental fragmentation predict their long term dynamics (24-25 years post fragmentation)? Yes and no. One group of species that was declining in the short term has continued to decline with some species now extinct in fragments, another group declined and then leveled off so that populations became lower but stable in fragments. Another group recovered in fragments. As more data are added, we will have greater power to report on these findings. Question 2: In the absence of "detailed" population dynamics data, do traits of species that predict short-term dynamics also predict long term dynamics? Traits that predicted species declines in response to fragmentation short term – natural rarity and isolation– predict fragment level extinctions in the long term. These results are based on only two years of data and should become clearer as more data are added. C. Results and accomplishments: broader impacts The project has been successful in undergraduate training. 1) Early in the project, a talented REU student created a 12 minute film about the Wog Wog experiment (vimeo.com/21249067). Both PIs teach eight weeks of Introductory Biology every spring to ~1300 students, collectively. A homework assignment based around the Wog Wog experiment has been used successfully over four years so far, and will continue to be used. 2) Five undergraduates have traveled to the field site in Australia to assist with the seasonal field sampling, and interact with the research group at CSIRO in Canberra. These trips are always transformative - all are pursuing careers in science. One student is a first generation college student. 3) We have employed 18 undergraduates who have been given substantial responsibility and received at least a year of research experience in the laboratory. 4) Finally, four PhD thesis projects and two post doctoral projects are based on the Wog Wog experiment as a direct outcome of this grant. D. Research products We have spent considerable effort to track down historic datasets and specimens. Many datasets were in paper workbooks or obsolete digital formats and we are continuing to curate these into modern informatics formats. New datasets include beetles and ants from two years of pitfall sampling so far, habitat surveys, environmental data from dataloggers, canopy photographs, site georeferences, tree productivity, lizard morphometrics, soil chemistry, soil nutrient status, and soil fungal and bacterial metagenomics. Many manuscripts are submitted or in preparation.
