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Summer Research Project 2020

  • Title: The Future of Harvard Forest: Seedling Demography and CO2 Enrichment Experiment
  • Group Project Leader: Sydne Record
  • Mentors: Paige Kouba; Sydne Record
  • Collaborators: Andrew Latimer
  • Project Description:

    Please note: This project will work in collaboration as a group project with other projects listed under "The Future of Harvard Forest"

    Over-arching Intellectual Theme
    Seedlings are often neglected in forest studies, in part because most seedlings do not survive to become adult trees. However, seedlings have the advantage of being amenable to manipulative experiments, and their recruitment and survival are a key determinant of forest regeneration after disturbances. The four students involved in this project will gain a familiarity with Northeastern forest species and learn experimental protocols for tree demography, ecophysiological, and biogeochemical studies. Students will also be encouraged to link their findings to theory within the ecological literature. We seek five students to work on three specific sub-projects and except students to spend some time collaborating within the sub-projects to gain exposure to different methodologies.

    Demography and CO2 Enrichment Experiment Project
    Simulating future climate change in a forest ecosystem is difficult due to the large sizes and long lifespans of trees. Seedlings, however, are amenable to manipulative treatments and measurement, and represent a critical bottleneck for determining future forest composition. This sub-project encompasses an observational demographic study and a manipulative experiment. The seedling demography project is part of an ongoing long-term study of tagged tree seedlings in the ForestGEO ( plot on Prospect Hill. The manipulative experiment is a new study this year in which we will conduct a miniature version of a free-air CO2 enrichment (FACE) experiment, growing tree seedlings in a controlled environment with elevated CO2 and varying degrees of water stress. Our focal species for the experiment are white pine, Eastern hemlock, red oak, and red maple (all species that also occur in the ForestGEO plot); data collected may include stomatal conductance, chlorophyll fluorescence, mid-day leaf water potential, and total biomass. Two students will work on this sub-project with roughly 50% of their time allotted to the observational study and 50% of their time allotted to the manipulative experiment. Sydne Record and Paige Kouba will co-mentor the students on this project.

    A typical week for these students will involve about 75% fieldwork, and 25% data entry and statistical analyses. Fieldwork for the observational demographic study will involve hiking to the ForestGEO plot, crouching to take seedling measurements, and helping to transport soil samples for sub-project two. This project will involve long (8 hour) days in the forest in hot, humid weather with lots of biting insects. Fieldwork for the manipulative experiment will involve spending time collecting measurements in the lath house, where it may get quite warm. We may also need to take measurements late at night or in the early morning. Students should be able to lift ~30 lbs. (e.g. flats of seedlings) and solve problems creatively. Students will meet with a mentor at least three times per week. They will use R statistical software to analyze the data they collect and will present these analyses at Harvard Forest’s end-of-summer research symposium. Students are encouraged to ask and pursue independent research questions of their own (which could be the basis for a senior thesis or other undergraduate research paper).

    General requirements for all overall project:
    1. Participate in field studies, including ~8 hours per field day crouching in a forest environment to measure seedlings with biting insects and hot, humid conditions.
    2. Hike with scientific gear (30-45 lb. pack) in rough, forested terrain.
    3. Willingness to work in a collaborative team of students and mentors.
    4. Have or develop a basic understanding of R for graphical and statistical analysis.
    5. Think critically about theoretical issues in forest demographics and ecophysiology and link them to field work and data analyses.
    6. Ask questions about everything from procedures to theoretical implications of our research.

  • Readings:

    Brodribb, T.J., Carriqui, M., Delzon, S., & Lucani, C. (2017). Optical measurement of stem xylem vulnerability. Plant Physiology 174, 2054-2061.

    Choat, B., Brodribb, T.J., Brodersen, C.R., Duursma, R.A., Lopez, R., & Medlyn, B.E. (2018). Triggers of tree mortality under drought. Nature, 558, 531-539.

    Kavanagh, K. L., Bond, B. J., Aitken, S. N., Gartner, B. L., & Knowe, S. (1999). Shoot and root vulnerability to xylem cavitation in four populations of Douglas-fir seedlings. Tree Physiology, 19(1), 31–37. doi: 10.1093/treephys/19.1.31

    Merow, C., Dahlgren, J.P., Metcalf, C.J.E., Childs, D.Z., Evans, M.E.K., Jongejans, E., Record, S., Rees, M., Salguero-Gomez, R., & McMahon, S. (2014). Advancing population ecology with integral projection models: a practical guide. Methods in Ecology and Evolution 5(2), 99-110.

    Messerli, J., Bertrand, A., Bourassa, J., Bélanger, G., Castonguay, Y., Tremblay, G., . . . Seguin, P. (2015). Performance of Low-Cost Open-Top Chambers to Study Long-Term Effects of Carbon Dioxide and Climate under Field Conditions. Agronomy Journal, 107(3), 916. doi:10.2134/agronj14.0571

    Miglietta, F., Hoosbeek, M. R., Foot, J., Gignon, F., Hassinen, A., Heijmans, M., . . . Wallén, B. (2001). Spatial and temporal performance of the MiniFACE (Free Air CO2 Enrichment) system on bog ecosystems in northern and central Europe. Environmental Monitoring and Assessment, 66, 107-127.

    Okada, M., Lieffering, M., Nakamura, H., Yoshimoto, M., Kim, H. Y., & Kobayashi, K. (2001). Free-air CO2 enrichment (FACE) using pure CO2 injection: System description. New Phytologist, 150(2), 251-260. doi:10.1046/j.1469-8137.2001.00097.x

    Pepin, S., & Körner, C. (2002). Web-FACE: A new canopy free-air CO2 enrichment system for tall trees in mature forests. Oecologia, 133(1), 1-9. doi:10.1007/s00442-002-1008-3

    Record, S., Kobe, R.K., Vriesendorp, C.F., & Finley, A.O. (2016). Seedling survival responses to conspecific density, soil nutrients, and irradiance vary with age in a tropical forest. Ecology 97(9), 2406-2415.

  • Research Category: Physiological Ecology, Population Dynamics, and Species Interactions, Large Experiments and Permanent Plot Studies, Group Projects