Are ground beetle populations decreasing? It depends on where you look and what species you look at. A recent paper in Global Ecology and Biology, Habitat–trait interactions that control response to climate change: North American ground beetles, explores the connections between climate change, habitat types, and ground beetle traits. The study could help researchers model which ground beetle species may be at risk and the habitats needing protection to preserve them.
in Global Change Biology: Fish community dynamics with climate change
Understanding biodiversity change is complicated by the fact that populations respond to climate and other species both through change in abundance and movement. Thirty years of fisheries data from the Gulf of Maine show that the mechanisms driving biomass trends vary across space, time, and species… [more]
Dynamics in the Gulf of Maine. (a) Prior and posterior food webs. Arrow width and color denote magnitude and direction of relationship, respectively. (b) Contributions to dynamics, averaged across strata. Density-independent and density-dependent growth correspond to environment–species and species–species interactions, respectively. (c) Phase planes examining haddock and cod biomass under environmental conditions in the years 1989 and 2000. Yellow points are estimated fixed points, and shaded area denotes range of observed biomass.
Tang, B., Roberts, S. M., Clark, J. S., & Gelfand, A. E. (2023). Mechanistic modeling of climate effects on redistribution and population growth in a community of fish species. Global Change Biology, 29, 6399–6414. https://doi.org/10.1111/gcb.16963
Assistant and Associate Professor positions, Terrestrial Ecology
The Nicholas School of the Environment invites applications for two tenure-track positions in Terrestrial Ecology, one at the Assistant Professor level and one at either the Assistant or Associate Professor levels. The successful candidates will contribute to an expanding focus on global environmental change as part of the Duke Climate Commitment and participate in the University Program in Ecology. We seek applicants who will establish widely recognized, externally funded research programs. Both positions are encouraged to capitalize on Duke’s traditional strengths in areas such as biodiversity, biogeochemistry, ecophysiology, forest ecology, tropical ecology, species interactions, watersheds, statistical science, and/or theory. Research on both plants and animals is encouraged as are technical frontiers in modeling, geo-spatial methods, experimental networks, and/or remote sensing. Combinations of broad-scale studies and site-based research that could use the Duke Forest and Marine Lab are welcome. The position will be based on Duke University’s main campus in Durham, North Carolina. The successful applicant will contribute to teaching, advising and service activities in the University and the applicant’s professional field. Teaching will be part of the Environment PhD, the professional Master of Environmental Management (MEM) and Master of Forestry (MF) , and undergraduate programs.
Duke University and The Nicholas School of the Environment are strongly committed to advancing inclusive excellence throughout our research, teaching, and service activities. A diverse faculty – defined broadly as representing a wide range of identities, lived experiences, and perspectives – is a prerequisite for excellence and is essential to driving innovation within our scholarly community. To achieve these goals, it is essential that all members of the community feel valued and welcome, that the contributions of all individuals are respected, and that all voices are heard. All members of our community are expected to uphold these values, and we seek to hire faculty who are passionate about increasing the participation and success of individuals from all different backgrounds and communities.
Interested candidates should submit the following by 20 October 2023: a cover letter (with contact information); three publications; a curriculum vitae; a three-page research statement that includes a description of past research accomplishments, plans for future research, and their experience and approach to mentoring and supporting a diverse and inclusive research environment; a one to two-page statement describing their teaching philosophy, previous experiences, future plans for teaching, and experience and approach to fostering an inclusive learning and mentoring environment for their students; and three reference letters.
Duke University is an Affirmative Action/Equal Opportunity Employer committed to providing employment opportunity without regard to an individual’s age, color, disability, gender, gender expression, gender identity, genetic information, national origin, race, religion, sex, sexual orientation, or veteran status.
on NPR: Poison ivy thriving with climate change and CO2
Elevated CO2 in Duke’s Free-Air CO2 Experiment (FACE) stimulated growth of woody plants, but none like poison ivy. Not only did it grow fast; it also increased toxicity. The interview includes PhD student Jackie Mohan and collaborator William Schlesinger on our studies of poison ivy growth in response to high CO2. The study showing this effect is here:
Mohan, J. E., L. H. Ziska, R. B. Thomas, R. C. Sicher, K. George, J. S. Clark, W. H. Schlesinger. 2006. Biomass and toxicity responses of poison ivy (Toxicodendron radicans) to elevated atmospheric CO2. Proceedings of the National Academy of Sciences. 103 (24): 9086.
Welcome to new PhD student Kira Meyer and technicians Emily Bolander, Gina Givens, and Jon Ley. Kira comes from the University of Bayreuth and is interested in savanna ecology. Emily, Gina, and Jon are with us from Boulder, Tallahassee, and Chapel Hill respectively, all interested in biodiversity and climate change.
The Research Center on Alpine Ecosystems (CREA Mont Blanc) has announced that the citizen science MASTIF study will become part of its phenology monitoring in France. Founded in 1996 and based in Chamonix, CREA Mont-Blanc has specialized in the study of natural mountain environments. For over 20 years, CREA Mont-Blanc has been combining high quality ecological research with communication and education initiatives. CREA Mont-Blanc is a pioneer and leader of citizen science in France and maintains a strong commitment to participatory science, aiming not only to encourage the understanding of ecology, but also to directly involve the public in innovative scientific research.
Qiu, T., …, and J. S. Clark. Masting is uncommon in trees that depend on mutualist dispersers in the context of global climate and fertility gradients. Nature Plants (2023). https://doi.org/10.1038/s41477-023-01446-5
Erratic seed crops may help trees confound their seed predators, but what does it do to the seed dispersers that trees need to insure successful germination?
Erratic fruit production, or “masting”, may be a strategy trees use to defend their seeds from the many mammals, birds, and insects that consume them. High carbohydrate, fat, and protein content makes seeds, fruits, and nuts among the highest quality plant foods in nature. The provisions needed to give seedlings a head start after germination place them at risk from seed predators. The lean years between large seed crops could keep seed predators at low levels—too low to wipe out a big seed crop that comes along at long intervals. The relatively rare big crop year can be the time to escape.
Sweet acorn oak (Quercus rotundifolia) crops in Andalucia fluctuate from year to year. They are an important resource for mammals and birds.
But there is a problem with this explanation for masting. The same tree species that attract seed predators may also depend on mammals and birds to disperse their seeds. These friends are so valuable that many tree species pack their fruits and nuts with extra resources and advertise them with colorful displays, all to attract their important mutualist dispersers.
Here is the conundrum. Wouldn’t the unreliable seed production that thwarts a tree’s enemies have the same negative impacts on their disperser friends? If masting effectively guards against enemies (it does), then perhaps the species that rely most heavily on disperser species must forego this defensive option.
An analysis of seed production in hundreds of tree species across five continents shows this mixed benefit of masting. Using the Masting Inference and Forecasting (MASTIF) network, our lab showed the relationship between masting behavior and mutualist dispersers. The tree species that depend most on vertebrate dispersers are the ones that avoid masting. In the temperate forests of the North America and Eurasia, oaks and firs are prolific mast species. Pines and spruces also mast, but to a lesser degree. Hickories and walnuts still less. Chestnut and the fleshy fruits of black gum, holly, hack- and sugarberry, persimmon, juniper, yew, and pawpaw, hardly at all—they are “reliable” resources.
The masting firs, pines, and spruce fall prey to birds and many rodents in the canopy and when they reach the forest floor. In the tree, conifers can defend their seeds in woody, resin coated cones, many of which are armed with spines—they are a mess to handle. Once on the forest floor the exposed seeds are rapidly depleted by rodents. With few mutualist dispersers, they are prime candidates for masting.
At the opposite extreme, rich, colorful fruits avoid wild fluctuations—they depend on their animal dispersers. There is still plenty of year-to-year variation, because a large expensive fruit is sensitive to moisture stress. A good two-week drought in mid-summer will see many trees abandoning much of their fruit crop—early abortion. This includes not only fleshy fruits like persimmon, hackberry (including nettle tree in Europe), and black gum. Acorns and hickory nuts also have high moisture content; they too will abort many partially developed seeds to trim the resource demand. Still, a string of years with suitable climate conditions can see reliable crops in many of these species, one after another.
The oaks are exceptional. Nutrient- and moisture-laden acorns are a target for many consumers. Still their size and moisture requirements place them at the mercy of dispersers that could “plant” them quickly. Escaping predators on the forest floor is not enough—unless rains persist through early germination, they risk desiccation. The new five-continent study in Nature Plants does not explain how trees mast. It does show that an effective strategy for enemies can be modified where it may inflict damage on mutualist friends.
Qiu, T., …, and J. S. Clark. Masting is uncommon in trees that depend on mutualist dispersers in the context of global climate and fertility gradients. Nature Plants (2023). https://doi.org/10.1038/s41477-023-01446-5
The working group Unravelling the role of intraspecific variability in tree species coexistence in tropical forests is meeting in Montpelier this week. The project organized by Ghislain Vieilledent and Isabelle Maréchaux answered the joint call for the SYNERGY CESAB-sDIV on “Coexistence and stability in high diversity communities”. Discussions, modeling, writing…
Benoit, Georges, Jim, Camille, Adam, Isabelle, Ghislain, Adam’s mom on Pic St Loupe
Climate change is shifting weather patterns and landscapes, and forcing animals to adapt in ways that may not be sustainable. Maggie and Lane discuss their research as part of the Climate Commitment at Duke University. Megaherbivores and birds here.
Trends in Ecology and Evolution has Spotlight articles that highlight important new papers. Greenspoon et al. in PNAS offer an ambitious effort to estimate global mammal abundance. This overview adds context. In terms of biomass, white-tailed deer come out on top…
Clark, J.S., 2023. The most abundant mammals on Earth. Trends in Ecology & Evolution, ISSN 0169-5347, https://doi.org/10.1016/j.tree.2023.05.001. New estimates of global mammal abundance that use relationships between traits, estimates of range size, and International Union for Conservation of Nature’s (IUCN’s) Red List categories to predict the biomass of thousands of species have been developed by Greenspoon et al. This approach and some of the challenges that contribute to these estimates are summarized here.
Kickoff NSF grant at Smithsonian Environmental Research Center
Collaborators met this week at SERC to finalize data collection plans for the growing season. The study to understand forest regeneration and climate change involves PIs Jim Clark (Duke), Ines Ibanez (U Michigan), Roland Kays (NCSU), Emily Moran (UC Merced), and Miranda Redmond (UC Berkeley). Upcoming field work includes seed production, forest recruitment, and wildlife populations across the continental US. Missing from photos are Roland (holding camera) and Miranda (virtual).
Join us next Tuesday, Lane will present her public PhD seminar entitled:
“The effects of global change on avian biodiversity”
3:30 pm, April 18
Field Auditorium
Reception follows on Grainger Hall roof. If you can’t join in person, Zoom here.
Avian communities have declined dramatically over the last several decades. I discuss how massive data, much of it crowd-sourced, can be used to understand and anticipate declines. Beginning with a comparison of two widely-used bird monitoring datasets, I identify and quantify biases in reporting rates. Next, I use the data to understand how winter climate and food availability influence bird movements and distributions. Finally, I demonstrate a novel modeling framework that expands the utility of joint species distribution models and apply it to the dynamics of a brood parasite and its host species.
Jared Lazarus from University Communications came by to interview lab manager Jordan Luongo and Sam Sutton. Jordan coordinates data collections across four continents, including field work, site negotiations, and contractors. Sam works with the team of students, postdocs, and technicians that travels North America for field sampling and processing samples in the lab.
Rare antelope declines with climate change in African savanna
Maggie’s work is quantifying how the combinations of climate and fire are influencing megaherbivores in Kruger National Park. Early results were presented last week at the Savanna Science Network Meeting. [link]
Climate response positive (red) or negative (blue) depends on habitat. Climate–habitat interactions at a NEON site near Vancouver, WA with LIDAR canopy height for 30 m plots. Symbol color is abundance change (increasing red, decreasing blue) for Pterostichus pensylvanicus from the historical baseline under climate change to 2100.
As one of the most diverse and economically important families on Earth, ground beetles are a key barometer of climate change. The effects of climate change must depend on species traits like body size, diet, and flight, and their differences in habitat requirements, but we do not yet know how. Our analysis shows that ground beetle community reorganization is governed by climate–habitat interactions (CHI), and much of the response can be explained by trait syndromes. The fact that habitat mediates warming impacts has immediate application to critical habitat designation for conservation.
The broad diversity of ground-beetle traits control their responses to climate change. Included here are runners (a, b, c, g), burrowers (f), flyers (a, b, d, e), predators (a, b, c, f, g), and herbivores (d, e).
Qiu, T., Bell, A. J., Swenson, J. J., & Clark, J. S. (2023). Habitat–trait interactions that control response to climate change: North American ground beetles (Carabidae). Global Ecology and Biogeography, 00, 1– 15. https://doi.org/10.1111/geb.13670
Masting Inference and Forecasting (MASTIF) aims to understand forest recovery, through the production of seed and seedling recruitment. Duke Professor James Clark talks about the effects of climate change on seed production in forests and his team’s research on quantifying those seedlings for the next generation’s forests. Featured are Lane and Maggie in the field and Jordan and Sam in the lab.
Large-fruit bushwillow with pod surrounded by four wings for wind dispersal even on the ground. Important browse for savanna megaherbivores .
African savanna ecology: ENV323/623 meets big animals
ENV323/623 is in Kruger National Park this week studying biodiversity and climate change. Only in the last 10,000 years have humans interacted with biodiversity in the absence of megafauna. This week students embedded with trophic diversity intact. The student blog is here.
Contributors are Francesca Chiappetta, Yikai Jing, Grace Tregidgo, Yu Hai, Jacob Carnes, Xuening Tang, Eliza Carter, Erel Amit, Bryan Graybill, Yuntian Bi, Natalie von Turkovich, Ross Fly, Matt Morris, Meech Carter, Nat Blackford, Elise Boos, Marisa Fajardo, Chloe Ochocki, Sara Haas, Sasha Iturralde, and Miao Hu
