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Author: James Clark, Ph.D.

Oldest bald cypress

Oldest bald cypress

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.

Chris, Jordan, Maggie, Lane, Jim, and Tong with the ancient one
species interactions
The global distribution of tree seed production

The global distribution of tree seed production

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

National Science Foundation

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Science Daily

Ecology Letters: Fecundity increases two orders of magnitude from boreal forest to wet tropics

Ecology Letters: Fecundity increases two orders of magnitude from boreal forest to wet tropics

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.

Journe, V et al. 2022. Globally, tree fecundity exceeds productivity gradients. Ecology Letters, DOI: 10.1111/ele.14012, pdf: EcologyLetters2022.

Dr. Ruben Palacio

Dr. Ruben Palacio

Ruben defended his thesis today, entitled “Strengthening conservation of biodiversity at local and regional scales“. This highly successful analysis of conservation issues for the Columbian Andes has already generated important publications, including:

Hazzi NA, Moreno JS, Ortiz-Movliav C, Palacio RD. 2018. Biogeographic regions and events of isolation and diversification of the endemic biota of the tropical Andes. Proceedings of the National Academy of Sciences 115:7985–7990.

Palacio RD, Kattan GH, Pimm SL. 2020. Bird extirpations and community dynamics in an Andean cloud forest over 100 years of land‐use change. Conservation Biology 34:677–687.

Palacio RD, Negret PJ, Velásquez-Tibatá J, Jacobson AP. 2021. A data-driven geospatial workflow to map species distributions for conservation assessments. Diversity and Distributions 27:2559–2570.

Palacio RD, Valderrama-Ardila C, Kattan GH. 2016. Generalist species have a central role in a highly diverse plant-frugivore network. Biotropica 48:349–355.

Palacio RD, Vidal-Astudillo V, Cárdenas G, Luna-Solarte J. 2017. Aves del municipio de Santiago de Cali, Valle del Cauca, Colombia. Biota Colombiana 18:228–238.

Dr. Ruben Palacio, PhD Ecology
Lane and Maggie organize People and Nature

Lane and Maggie organize People and Nature

The 2022 People and Nature Symposium, organized by Lane Scher, Anita Simha, Jon Choi, Maggie Swift, Alex Loomis, and Brandie Quarles will take place on Saturday, April 09, 2022. A schedule will follow after abstracts have been selected for presentation; abstract submission will open in February 2022. Web link to register here.
Becky Tang: Student paper award from the Amer Statistical Assoc

Becky Tang: Student paper award from the Amer Statistical Assoc

Becky is recognized for her paper, “Modeling spatially biased citizen science effort through the eBird database” in Environmental and Ecological Statistics. This paper also received the Best Award from the Department of Statistical Science.

Tang, B., J. S. Clark, and A. E. Gelfand. 2021. Modeling spatially biased citizen science effort through the eBird database. Environmental and Ecological Statistics,

Chase Nunez evaluates climate change in central African forests

Chase Nunez evaluates climate change in central African forests

To evaluate the response of diverse Afrotropical forest communities we employ country-wide tree species inventories, remotely sensed climate data, and future climate predictions collected from 104 one-ha plots in the central African country of Gabon. We predict a 3–8% decrease in Afrotropical forest species richness by the end of the century, in contrast to the 30–50% loss of plant diversity predicted to occur with equivalent warming in the Neotropics… [more]

Winning and losing tree species under two climate change scenarios, accounting for dependence between species.

Nunez, C.L., J. R. Poulsen, L.J.T. White, V. Medjibe, and J. S. Clark. 2021. Distinct community-wide responses to forecasted climate change in Afrotropical forests. Frontiers in Ecology and Evolution, nunezFEVO,

Shubhi Sharma leads tree migration study in PNAS

Shubhi Sharma leads tree migration study in PNAS

Suitable habitats for forest trees may be shifting fast with recent climate change. Studies tracking the shift in suitable habitat for forests have been inconclusive, in part because responses in tree fecundity and seedling establishment can diverge. Analysis of both components at a continental scale reveals a poleward migration of northern species that is in progress now. Recruitment and fecundity both contribute to poleward spread in the West, while fecundity limits spread in the East, despite a fecundity hotspot in the Southeast. Fecundity limitation on population spread can confront conservation and management efforts with persistent disequilibrium between forest diversity and rapid climate change. [more]

NSOE coverage

University of California-Merced

The Source

Eureka Alert

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Sara Roberts on fisheries responses in Scientific Reports

Sara Roberts on fisheries responses in Scientific Reports

Sara Robert’s new paper shows how the community of fishes responding to environmental change: “Single species distribution models (SSDMs) are typically used to understand and predict the distribution and abundance of marine fish by fitting distribution models for each species independently to a combination of abiotic environmental variables.” [more]

Roberts, S.M., Halpin, P.N. & Clark, J.S. 2022. Jointly modeling marine species to inform the effects of environmental change on an ecological community in the Northwest Atlantic. Scientific Reports 12, 132.

Niche shifts from adults to fecundity to regeneration for North American Forests

Niche shifts from adults to fecundity to regeneration for North American Forests

Tree distribution and abundance depend not only on climate, but also on habitat variables, such as soils and drainage, and on competition beneath a shaded canopy. Using conditional models to compare the communities represented by joint fecundity and recruitment responses we expose a reorganization across life stages that will contribute to the next generation of forests. Tree fecundity is regulated by temperature to a greater degree than other life-history stages. Recruitment rates are most sensitivity to interactions between climate and habitat variables. Communities reorganized from adults to fecundity, but there is a re-coalescence of community types as seedling recruitment partially reverts to community structure similar to that of adults…[more]

Joint sensitivity taken over all species for adult abundances, conditional recruits (left y-axis with black color), and fecundity (right y-axis in green). Sensitivity is shown as a fraction of the total variance explained for each variable. Posterior medians are show with 95% credible intervals (whiskers).
Map of community assemblages (A) and reorganization as an alluvial diagram (B). Community clustering in (A) is based on adult tree response matrix. (B) Shifts in assemblages across the three demographic stages (adult, fecundity, and conditional recruits) in eighty-seven species.

Qiu, T., S. Shubhi, C. W. Woodall, and J.S. Clark. 2021. Niche shifts from trees to fecundity to recruitment that determine species response to climate change. Frontiers in Ecology and Evolution 9, 863., DOI10.3389/fevo.2021.719141.

Make Our Planet Great Again seminar series

Make Our Planet Great Again seminar series

Mondays, 12 eastern/6 Paris:

the Paris Agreement on Climate Change demands ”an effective and progressive response to the urgent threat of climate change on the basis of the best available scientific knowledge‘’. Unequivocal evidence suggests that recent global climate change is caused by human activities and leads to global warming, sea level rise, ocean deoxygenation and acidification, water shortage, crop and biodiversity loss, increased frequency and severity of storm events, as well as other local to global repercussions (Intergovernmental Panel on Climate Change). Signatories of the Paris agreement have therefore pledged to hold “the increase in the global average temperature to well below 2°C above pre-industrial levels”, “recognizing that this would significantly reduce the risks and impacts of climate change”.

The “Make Our Planet Great Again” program is a French – German initiative to foster climate change research and to support the implementation of the Paris Agreement. Within the “Make Our Planet Great Again” program, researchers from all over the world work together to improve Earth system observations, to detect impacts and suggest strategies to mitigate and adapt to Climate change and to find new solutions for the necessary Energy transition from fossil fuels to renewable resources.

The Make Our Planet Great Again seminar series takes place on Mondays from 16:00 to 17:00 Paris/Berlin time. The seminar series is an open event at which the Make Our Planet Great Again Laureates will inform about the latest developments in their research area.

Please join us by registering for this open seminar series at:

You will find further information about the upcoming seminar topics in attached document.

Tong Qiu leads global study on tree senescence in PNAS

Tong Qiu leads global study on tree senescence in PNAS

Contrary to expectation, this study shows that seed production eventually declines with tree size and age. A global analysis finds that fecundity decline in large trees is pervasive, consistent with physiological decline, thus providing new evidence for tree senescence. Read more

Carpinus betulus shows changes in architecture that occur with aging (SE France, photo Jim Clark)

See coverage in:

PNAS Research Highlights

The Scientist

le Figaro, 23 August

Duke Daily


National Science Foundation

Tong Qiu, Marie-Claire Aravena, Robert Andrus, Davide Ascoli, Yves Bergeron, Roberta Berretti, Michal Bogdziewicz, Thomas Boivin, Raul Bonal, Thomas Caignard, Rafael Calama, J. Julio Camarero, Connie J. Clark, Benoit Courbaud, Sylvain Delzon, Sergio Donoso Calderon, William Farfan-Rios, Catherine A. Gehring, Gregory S. Gilbert, Cathryn H. Greenberg, Qinfeng Guo, Janneke Hille Ris Lambers, Kazuhiko Hoshizaki, Ines Ibanez, Valentin Journé, Christopher L. Kilner, Richard K. Kobe, Walter D. Koenig, Georges Kunstler, Jalene M. LaMontagne, Mateusz Ledwon, James A. Lutz, Renzo Motta, Jonathan A. Myers, Thomas A. Nagel, Chase L. Nuñez, Ian S. Pearse, Łukasz Piechnik, John R. Poulsen, Renata Poulton-Kamakura, Miranda D. Redmond, Chantal D. Reid, Kyle C. Rodman, C. Lane Scher, Harald Schmidt Van Marle, Barbara Seget, Shubhi Sharma, Miles Silman, Jennifer J. Swenson, Margaret Swift, Maria Uriarte, Giorgio Vacchiano, Thomas T. Veblen, Amy V. Whipple, Thomas G. Whitham, Andreas P. Wion, S. Joseph Wright, Kai Zhu, Jess K. Zimmerman, Magdalena Żywiec, and James S. Clark. 2021. Is there tree senescence? The fecundity evidence. Proceedings of the National Academy of Sciences 118 (34) e2106130118; DOI: 10.1073/pnas.2106130118. pdf

(Duke and Grenoble INRAE contributors in bold font)