Food web efficiency in desert streams

With a dedicated group and a lot of field work, we quantified food web efficiency (fish production/gross primary production) in nine desert streams. Food web efficiency was negatively related to light, water temperature, and variation in streamflow, but was unrelated to gross primary production. These patterns in part confirm previous results from mesocosms, but add understanding of the role of disturbance by scouring floods.

Baruch, E. M., T. K. Harms, A. Ruhi, M. Lu, L. Gaines‐Sewell, and J. L. Sabo. 2023. Food web efficiency in desert streams. Limnology and Oceanography. https://doi.org/10.1002/lno.12305

Coupled carbon & nitrogen cycles: Soil C suppresses nitrification

A continental-scale synthesis of nitrogen mineralization and nitrification assays from sites in the Long-Term Ecological Research Network, including our previous work from boreal and Arctic sites, confirmed a role of soil organic carbon in nitrogen dynamics. Soils containing high concentration of organic carbon, including the boreal forest and arctic tundra, support lower rates of nitrification relative to mineralization than sites with less carbon.

Gill, A. L., R. M. Grinder, C. R. See, F. S. Chapin, L. C. DeLancey, M. C. Fisk, P. M. Groffman, T. Harms, S. E. Hobbie, J. D. Knoepp, J. M. H. Knops, M. Mack, P. B. Reich, and A. D. Keiser. 2023. Soil carbon availability decouples net nitrogen mineralization and net nitrification across United States Long Term Ecological Research sites. Biogeochemistry.

On the future of ecological synthesis

A large working group organized by the National Center for Ecological Analysis and Synthesis recently summarized priorities for synthesis in ecology. Priorities include addressing social inequities in ecological processes and increasing data access, understanding coupled human-natural systems, tackling the enormous theoretical challenges of scale and scaling, addressing resilience of complex systems, and increasing our ability to predict the outcomes of ecological processes.

Halpern, B. S., C. Boettiger, M. C. Dietze, J. A. Gephart, P. Gonzalez, N. B. Grimm, P. M. Groffman, J. Gurevitch, S. E. Hobbie, K. J. Komatsu, K. J. Kroeker, H. J. Lahr, D. M. Lodge, C. J. Lortie, J. S. S. Lowndes, F. Micheli, H. P. Possingham, M. H. Ruckelshaus, C. Scarborough, C. L. Wood, G. C. Wu, & >100 others, including T.K. Harms. 2023. Priorities for synthesis research in ecology and environmental science. Ecosphere 14. https://doi.org/10.1002/ecs2.4342

Celebrating the contributions of Dr. Nancy Grimm to hydrologic sciences

Our invited synthesis of Dr. Nancy Grimm’s contributions to hydrology is now available. What a joy to work with a group of Grimm’s mentees to reflect on an innovative career spanning desert streams & catchments, cities, and urban resilience.

McPhillips, L., M. Berbés-Blázquez, R. Hale, T. K. Harms, V. Bisht, L. Caughman, S. M. Clinton, E. Cook, X. Dong, J. Edmonds, S. Gergel, R. Gómez, K. Hopkins, D. M. Iwaniec, Y. Kim, A. Kuhn, L. Larson, D. B. Lewis, E. Martí, M. Palta, W. John Roach, and L. Ye. 2023. Learning from arid and urban aquatic ecosystems to inform more sustainable and resilient futures. Journal of Hydrology 616:128841.

Recruiting post-doc in hydro-biogeochemistry data synthesis

The Harms lab is recruiting a post-doctoral researcher with expertise and interests in biogeochemistry, hydrology, and data synthesis. The researcher will join a collaborative team funded by the NASA ABoVE program to decrease uncertainty in estimates of high-latitude C balance by incorporating lateral fluxes and landscape change. The post-doctoral researcher will lead synthesis of data describing spatial and temporal patterns in riverine fluxes of water, carbon, and nitrogen in permafrost-influenced regions of Alaska and northern Canada. The researcher will apply statistical approaches for time series to quantify long-term trends and shorter-term temporal patterns in river discharge and chemistry as a function of climate, landscape attributes, and permafrost thaw.

Expected start date is by Jan 2023. Remote work is possible. Prospective applicants should contact Dr. Harms (tamara.harms@alaska.edu) by Oct 20 with a CV, a cover letter describing research interests and experience, and the names and contact information for three references.

Cumulative biogeochemical activity of river networks scales non-linearly with watershed area

Using theoretical river networks, we found that cumulative biogeochemical processing scales superlinearly (i.e., power function with a positive scaling exponent) as a function of watershed area. Biogeochemical activity occurs primarily in the streambed and streambed area increases suplerinearly with watershed area. This finding highlights a major role of large rivers in contributing to the function of river networks in the Earth system.

Recruiting undergraduate researchers for summer 2022

Summer Research Experience for Undergraduates (REU) at the Bonanza Creek Long-Term Ecological Research Program, Fairbanks, Alaska

The Bonanza Creek (BNZ) Long-Term Ecological Research Program (https://www.lter.uaf.edu/) is recruiting undergraduate students to contribute to ecological research in the boreal forest, summer 2022. The BNZ program studies responses of boreal ecosystems to fire, permafrost thaw, and changing climate. Students will complete independent research projects related to one of the following topics:

1) disease ecology and genetics of aspen canker

2) nutrient cycling in streams draining fire and thawing permafrost

3) microbial genomics of coupled mercury and carbon cycling

4) carbon dynamics in boreal streams

5) greenhouse gas production in thawing permafrost

Students will gain training in laboratory procedures, field work, research design, and data analysis. REU students will participate in weekly professional development seminars and will present their research in a symposium at the end of the program. The 10-week program will include a stipend, housing allowance, travel to Alaska, and research funds.

Applicants must be current undergraduate students (graduating Fall 2022 or later). To apply, submit a cover letter, CV or resume, and contact information for two professional references as a single pdf titled with your last name to uaf-arctic-lab@alaska.edu by March 20. Your cover letter should include:

-description of your interests in ecological research

-list of relevant coursework in science and math/statistics

-your educational and career objectives

-your expectations for a successful summer research experience

-identify at least one of the five research topics described above that you are interested in pursuing

Widespread potential for denitrification activity in the boreal forest

New paper led by Melanie Burnett describes potential rates of denitrification and nitrous oxide production in soils and sediments of Interior Alaska. Riparian soils harbored greatest capacity for denitrification, followed by streams and upland soils. Thermokarst lakes typically supported little potential denitrification. Gaseous loss of nitrogen requires integration into the high-latitude nitrogen cycle.