Combining datasets helps identify biodiversity threats–if we can account for their different observation biases. eBird is a citizen science project with variable geographic coverage and observer effort. The Breeding Bird Survey (BBS) is a structured survey repeated each year. Together, they offer a massive resource on bird distribution and abundance. To combine them, we have to account for variation in habitat, time of day, observer effort and expertise (many eBirders are novices), and even the tendency of different species to be observed together.
The differences can be substantial. BBS observers count more species per observation effort, especially species that are common and detected by sound. eBirders count more “popular” and wetland species. Species typically identified by sound are reported more at sunrise than late morning. This knowledge of their biases is now being used to synthesize data from both sources.
Scher, C.L. and J.S. Clark. 2023. Species traits and observer behaviors that bias data assimilation and how to accommodate them.Ecological Applications, in press.
Small mammal abundance in NEON: Arielle Parsons’ paper in Mammalogy
Reliable estimates of small mammal abundances are important for understanding community interactions. While capture–recapture estimates of absolute abundance are preferred, indices of abundance continue to be widely used. Calibrating with absolute abundance can improve these indices, but their reliability across years, sites, or species is unclear. We used the US National Ecological Observatory Network capture–recapture data for 63 small mammal species over 46 sites from 2013 to 2019… [more]
Monitoring small mammal abundance using NEON data: are calibrated indices useful?
Understanding how communities respond to environmental change is frustrated by the fact that both species interactions and movement affect biodiversity in unseen ways. Tang et al. show that combined effects of species interactions and movement can be estimated for eBird data. [more]
Tang, B., J.S. Clark, P.P. Marra, and A.E. Gelfand. 2022. Modeling community dynamics through environmental effects, species interactions and movement. Journal of Agricultural Biological and Environmental Statistics, https://doi:10.1007/s13253-022-00520-3.
This workshop will be centered around ecological research and entails (1) an overview lecture by Dr Katti about the tenets of decoloniality in research, (2) jigsaw-style breakout sessions to discuss how these tenets connect to individual research, and (3) a final discussion and debrief. Breakfast, coffee, and snacks will be provided. Contact firstname.lastname@example.org for any questions or concerns.
Evaluate the science of biodiversity and climate change, including changes happening now, in the past, and what we can expect in the future. The issues are focused by three contrasting case studies, including the field trip to Kruger National Park, South Africa, during spring break. Topics include woodland diebacks, intensifying drought, increased wildfire, insect and pathogen outbreaks, and poleward migrations of populations. We take a food-web approach, considering how species interactions respond dynamically to global change. Class activities include lectures, working group collaborations, class discussions, and the field trip. Analytical tools used to quantify change include data manipulation in R, including data sets collected during the course. Examples include population size and growth, regression, GLMs, and species distribution modeling. Prerequisites: statistics.
Bill Schlesinger and Bev Law wrote and gathered consensus for a letter to USFS and BLM as part of their planning for the executive order on conservation of old-growth forests. Their op-ed on The Hill is here.
A new collaboration to understand forest regeneration and climate change will be led by Jim Clark, in collaboration with University of California Merced, University of California Berkeley, University of Michigan, and the North Carolina Museum of Natural History. The award will involve sampling seed production and wildlife populations across the continental US.
The sustainability of North American forests depends on seed production by trees and the seedlings that must establish the next generation. For most of North America, neither the amounts of seed that are produced, nor how much of that seed survives to become future forests is known. Planning for climate change requires this knowledge to anticipate tree species migrations and its impacts on the birds and mammals that depend on forests for habitat and food. This study combines continental scale tree fecundity estimates with a new generation of monitoring and synthesis methods for integrating tree fecundity, seedling success, and its impacts on animal consumers. The study will quantify current trends across the continent, the changes in forests that are happening now, and the habitat changes that are causing them. [more]
Stages critical to the conservation of forest communities with climate and habitat change, including tree fecundity (F), seed consumers (C), seed dispersers (D), and seedling browsers (B)
Predictive steady-state abundance for each species group across observed gradients of ambient (left) and augmented (right) N deposition (zero centred ± two standard deviations) in global change plots. Points show simulated equilibrium abundances (100 at each value of ×).
Maggie collaborated using gjamTime to understand dynamic species interactions in response to climate change. Density-dependent shifts in competitive interactions drove long-term changes in abundance of species-groups under global change while counteracting environmental drivers limited the growth response of the dominant species through density-independent mechanisms. Furthermore, competitive interactions shifted with the environment, primarily with nitrogen and drove non-linear abundance responses across environmental gradients [more]
Collins, C.G., Elmendorf, S.C., Smith, J.G., Shoemaker, L., Szojka, M., Swift, M., and K. N. Suding. 2022. Global change re-structures alpine plant communities through interacting abiotic and biotic effects Ecology Letters, 25, 1813-1826. https://doi.org/10.1111/ele.14060
New research finds that North Atlantic right whales with severe injuries are more likely to die than those with minor ones, making entanglements the leading cause of serious injury and mortality in the critically endangered species. The research underscores the urgent need for changes to the fishing industry as the species, with an estimated population of less than 350 individuals, faces extinction. The study, published in Conservation Science and Practice, also found that sub-lethal effects on reproductive success are more pronounced than previously recognized. Read more…
(Left) Female right whale “Bayla” last seen in good health with no fishing gear on Feb. 23, 2010. (Middle) Sighted with attached gear and severe injuries on Dec. 25, 2010, and (right) found dead Feb. 1, 2011 after an unsuccessful disentanglement effort. She was 2 years old. CREDIT: Florida Fish and Wildlife Conservation Commission, taken under NOAA research permits #594-1759 and #932-1905/MA009526
This summer, there are five people working with Renata’s urban tree-health study, two in Chicago and three in Durham. The three Durham technicians are Chloe Schueller, Maggio Laquidara, and Lucie Ciccone. They will each examine different aspects tree health across the city of Durham and the Duke campus. Topics include impacts of maintenance on tree health, urban bird habitats, and the social and political factors that influence tree health in cities. Renata’s site includes bios.
Lorenzo Maggio Laquidara, technicianChloe Schueller, Technician
POLONEZ BIS is co-funded by the European Commission and the Polish National Science Centre under the Marie Skłodowska-Curie COFUND grant. In three calls to be announced in 2021 and 2022 the programme will recruit 120 experienced researchers from all over the world. They will move to Poland for 24 months to conduct their basic research in public or private institutions of their choice. Valentin will be collaborating with Michal Bodgziewicz and Jim Clark on masting dynamics.
Tong will start at Penn State University in October 2022. Meanwhile, he’ll complete projects here are Duke focused on remote sensing, tree fecundity, and ground beetle ecology. His highly productive postdoc years include the publications listed here.
Some of us trekked down the Black River to trees aged by Dave Stahle at > 2600 yr. Led by Don of Mahanaim Adventures, we entered the ancient stand from upstream. Continuing drought in the Southeast left us to portage the swamp interior. Many large trees have snapped in this hurricane-battered watershed, but blowdowns within the cypress groves are rare. Knees emerge from a tangle of roots that appears to anchor the entire stand against windthrow.
Overcup oak (Quercus lyrata) is the most abundant oak along the riverCarolina ash (Fraxinus caroliniana) is a dominant understory tree within the cypress swampChris, Jordan, Maggie, Lane, Jim, and Tong with the ancient onespecies interactions
A forest’s ability to regenerate after devastating wildfires, droughts and other disturbances depends largely on seed production. Findings from two new studies led by Duke University and INRAE (France’s l’institut national de recherche pour l’agriculture, l’alimentation et l’environnement) researchers could boost recovery efforts by providing foresters with new guidance on which trees species produce more seeds and how their productivity varies from place to place. [more]
Regeneration of forests devastated by multi-year drought and fire depend on a vastly diminished seed supply. a) Seed production is limited to unburned landscape fragments in the Sierra Nevada mixed conifer zone following 2020 burns. b) Total reproduction includes not only seeds, but also defenses, including wood, spines, and resin flow in conifer cones; examples from the heavily burned Sierra Nevada and Coast ranges include Calocedrus decurrens, Pinus albicaulis, P. contorta, P. coulteri, P. flexilis, P. lambertiana, P. monophylla, P. monticola, P. ponderosa, P. radiata, P. sabiniana, Pseudotsuga menzesii, Sequoiadendron giganteum, and Tsuga mertensiana. Photo credits: James S. Clark and Jordan Luongo.
“Limits to Reproduction and Seed Size-Number Trade-offs That Shape Forest Dominance and Future Recovery,” Tong Qiu, James S. Clark et al. Nature Communications, May 2, 2022. DOI: 10.1038/s41467-022-30037-9
“Globally, Tree Fecundity Exceeds Productivity Gradients,” Valentin Journé, James S. Clark, et al. Ecology Letters, April 23, 2022. DOI: 10.1111/ele.14012
Online this week in Ecology Letters: In MASTIF, the discovery of a 250-fold increase in seed abundance from cold-dry to warm-wet climates, driven primarily by a 100-fold increase in seed production for a given tree size. This 100-fold gradient in seeds per tree size is amplified to a 250-fold gradient by the predominance of larger trees in the wet tropics. The modest (threefold) increase in net primary production (NPP) across the same climate gradient cannot explain the magnitudes of these trends. The increase in seeds per tree can arise from adaptive evolution driven by intense species interactions or from the direct effects of a warm, moist climate on tree fecundity. Either way, the massive differences in seed supply ramify through food webs potentially explaining a disproportionate role for species interactions in the wet tropics.
NPP shows a 3-fold increase from boreal to wet tropics, while seeds per tree basal area (ISP) increases 100-fold, and seeds per forest area (CSP) increases 250-fold.