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Summer Research Project 2019

• Title: Seasons to Years: Wood Formation in Trees
• Group Project Leader: Tim Rademacher
• Mentors: Tim Rademacher
• Collaborators: David Basler; Andrew Richardson
• Project Description:

  Trees, like all plants, eat sunlight and transform air and water into sugar. Most of that sugar goes into metabolism and short-lived structures such as fine roots and leaves. However, trees also produce wood, which persists aboveground for decades to centuries. That wood, concentrated in the trunk, makes trees stand tall, structure ecosystems, produce fuel and fiber, and sequester vast quantities of carbon. How much wood a tree forms in a given year is a function of abiotic (soil, climate) and biotic (age, species, competition from neighbors) factors.
  
  Seasons: How trees use and loose carbon (1 student)
  Temperate forests cover 6% of the global terrestrial surface, yet they take up 13% of the total amount of carbon absorbed by vegetation every year. Projections of future uptake of carbon are consistently increasing, because rising atmospheric CO2 concentrations are expected to boost photosynthesis. One important, yet understudied aspect of the carbon cycle is what happens to this additionally fixed carbon in trees. The additional carbon is often assumed to simply increase wood production, based on the assumption that wood production is currently limited by carbon availability. However, there is ample evidence that wood production is more often than not constrained by other factors. To better understand how temperate forest trees use and loose carbon, we use experimental chilling and strangling treatments to influence the carbon availability within the stem of mature trees and monitor the effects on key processes such as wood production and respiration.
  
  The student working on this project will primarily help with tree physiological measurements, including stem respiration, photosynthesis, leaf transpiration, and water potential measurements (30% of their time). They would also assist with building and monitoring the experimental setup, as well as entering, analyzing and visualizing data. Programming skills, particularly in the computing language R, would be useful, but are not required. Similar projects in the past have involved lots of field work with early mornings as well as all-night measurements, including everything that comes with it, such as carrying heavy objects, bugs, poison ivy, ticks, and the typical extremes of New England summer weather.
  

• Readings:

  Allen, C.D., A.K. Macalady, H. Chenchouni, D. Bachelet, N. McDowell, M. Vennetier, T. Kitzberger, A. Rigling, D.D. Breshears, E.T. Hogg and P. Gonzalez. 2010. A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests. Forest ecology and management, 259(4), 660-684.
  
  Andreu, L., Gutiérrez, E., Macias, M., Ribas, M., Bosch, O. and Camarero, J.J., 2007. Climate increases regional tree‐growth variability in Iberian pine forests. Global Change Biology, 13(4), pp.804-815.
  
  Belmecheri, S., Maxwell, R.S., Taylor, A.H., Davis, K.J., Freeman, K.H. and Munger, W.J., 2014. Tree-ring δ 13C tracks flux tower ecosystem productivity estimates in a NE temperate forest. Environmental Research Letters, 9(7), p.074011.

• Research Category: Physiological Ecology, Population Dynamics, and Species Interactions, Ecological Informatics and Modelling