Jill Bubier's Lab

Strategies for Understanding the Effects of Global Climate and Environmental Change on Northern Peatlands

The main objective of my research plan is to improve our understanding of feedbacks between peatland ecosystems and the atmosphere in response to global climate change and increasing atmospheric nitrogen deposition through a combination of research and educational activities with undergraduate women students at Mount Holyoke College and collaborations with peatland scientists in Canada, U.S. and Finland. I propose a Cascade Mentoring approach where students evolve from research assistants to full collaborators in furthering our understanding of three main topics: (1) the environmental controls on interannual and seasonal variability in CO2 and CH4 gas exchanges, (2) the different responses of a range of plant communities along hydrologic and nutrient gradients to climate variability, and (3) the influence of nitrogen deposition on carbon exchanges and vegetation community composition. I will build on a strong foundation of research and undergraduate student training accomplished during the last 5 years at a boreal bog and temperate fen to test hypotheses focused on two primary questions: How do changes in temperature and moisture availability on short-term (daily) and longer-term (seasonal and interannual) scales affect C cycling in different plant communities in bog v. fen ecosystems? How does atmospheric N deposition affect C cycling in northern peatlands?

The field component consists of measurements of carbon and nitrogen dynamics across wide ranges of plant community, hydrologic and nutrient gradients at a low boreal bog in Ottawa, Ontario (Mer Bleue Bog) and a temperate poor fen in southern New Hampshire (Sallie’s Fen). Comparing bog and fen, two of the most common peatland types in North America, is a unifying theme throughout this research program. Measurements include CO2 and CH4 gas exchange using manual and automatic chambers, plant production and decomposition experiments, a fertilization experiment to test the response of ecosystems to nitrogen and phosphorus additions, and monitoring plant community and environmental parameters. Preliminary data from the research thus far has raised intriquing questions that are the focus of this proposal. Undergraduate women students at Mount Holyoke College are an integral part of this research program.

The broader impacts of the plan include a Cascade Mentoring model, which trains students to become research collaborators by following the sequence of trainee during the first summer, mentor to new undergraduate research assistants in the second summer, and finally designers of scientific studies and authors of honors research theses leading to presentations at major scientific meetings and publication in peer-reviewed journals. Evaluation of student learning is a critical aspect of the process. The collaborations with scientists from major research universities in Canada and U.S. are also critical for training undergraduates, exposing them to vibrant research communities of graduate students, postdoctoral fellows and faculty, and improving our knowledge of the complexities of carbon cycling in northern peatlands through interdisciplinary research. I propose to foster collaborations with colleagues from University of Helsinki and University of Kuopio in Finland to exchange ideas on carbon and nutrient cycling in peatlands across the boreal and subarctic region, and to begin a new research and education program with a consortium of Finnish scientists on the effect of UV-B radiation and atmospheric ozone on CO2 and CH4 flux in peatlands. The plan also involves development and revision of core and advanced courses such as Environmental Science and Biogeochemistry of Northern Ecosystems. These courses are inquiry-based and involve student-directed research, hypothesis testing, data collection and analysis, and writing. With improvements to these courses with new laboratory components and equipment, I plan to build a strong foundation for students to participate in interdisciplinary research.

Lisa Brunie'06
Last summer I started working for Professor Bubier at Sallie's Fen in New Hampshire. I worked on measuring CO2 and CH4 emissions from the fen. I was also given the opportunity to become familiar with the LiCor 6400.which is used to investigate leaf level photosynthesis. This summer (2005) I will continue to work for Professor Bubier and will begin collecting data for my thesis at Mere Bleue Bog in Ottawa, Ontario, Canada. I am currently working on defining my thesis project but might be interested in using the 6400 again to compare the functioning of different plant species.

Thesis: Plant Response to Fertilization at a Cool Temperate Peatland
ABSTRACT

   Peatlands are nutrient-limited ecosystems. Human activities are causing an increase in nitrogen (N) deposition, which may lead to fertilization of bogs and alter vascular plant densities and biomass. N deposition affects ecosystem function, and potentially alters the system’s ability to sequester carbon. In the summer of 2005 we measured this effect in an ombrotrophic bog, Mer Bleue, near Ottawa, Canada with a fertilization experiment established in 2000.
   We measured leaf-level CO2 exchange with a LI-6400 portable photosynthesis system. We used these data to calculate the maximum rate of photosynthetic capacity (Vmax) between the high fertilization (20NPK, 20 times the ambient summer N deposition, or 6.4 g N m-2 as NH4NO3, and 6.3 g P m-2, 5.0 g K m-2 as KH2PO4) treatment plots and control plots. We quantified above ground vascular plant biomass through non-destructive measurements of stem height and stem number within the 0.6 x 0.6m quadrat where we measured net ecosystem CO2 exchange. We destructively measured shrub biomass, number of leaves, leaf size, number of stems, C: N ratio of the leaves, and stem length for clipped plant samples collected from outside the CO2 measurement quadrats. We also measured leaf area index, the mass of litter and litter cover with in the 0.6x 0.6m quadrats.
   After five years of nutrient addition, above ground biomass of shrubs significantly increased between the control and high fertilization plots (20NPK). This pattern is perhaps explained by the increase in both stem length and leaf area with the fertilizer addition. A decrease in C: N ratio suggests that plants in the fertilizer treatments are taking up the added nutrients. However, an important difference was found in the leaf level photosynthesis data, which showed a significant decrease in Vmax between the control and the high fertilization treatment. These results have important implications for the ecosystem response to environmental changes. The increase in biomass and litter production of vascular plants will have effects on carbon storage as a result of the decomposability of this matter. The increase in biomass may be offset by decreases in leaf-level photosynthesis, potentially altering the carbon uptake within the system.

Gareth Crosby'05 has been working with advisor Jill Bubier for the past two summers on climate change research at Mere Bleue Bog in Ottawa Canada. With data taken from the past two summers she is working on a thesis on peatland vegetation patterns in response to water table gradient changes and the implications of climatic change on methane emissions. It has been found that some species actually aid in methane release from bogs. Since methane is an important greenhouse gas, a loss of a certain type of vegetation could have an important impact on methane accumulation in the atmosphere.

Bubier, J., T. Moore, and G. Crosby*. 2006. Fine-scale vegetation distribution in a cool temperate peatland. Can. J. Bot., 84, 910-923. [Full text]

Claire Treat'05
    This year, I am looking at the environmental controls on interannual and seasonal variability of methane emissions from the fen. I’m trying to pin down more concrete trends both between different seasons and during the growing season, trends by vegetation types, and also trends in relationships with net ecosystem exchange and its components, photosynthesis and respiration.
       Claire with Dr. Jill Bubier (MHC) and Dr. Ruth Varner (University of New Hampshire) presented "Variations in Methane Emissions and Net Ecosystem Exchange in a Temperate Peatland, 2000-2004" in Washington, DC in 2004 meeting, for the Research and Discover Program, at NASA-Goddard Space Flight
Center.
      Abstract: Global climate change has the potential to greatly affect carbon storage in peatlands, which store about 30% of the pool of global soil carbon. Increasing temperature may cause peatlands to function either as a sink or a source of C to the atmosphere. Whether the ecosystem will store or lose carbon is uncertain: climate change may lead to increased plant productivity and C storage, while it could also lead to increased respiration and C loss as both CO2 and methane. This ecosystem dynamic can be measured by net ecosystem CO2 exchange (NEE), which is the sum of two components: photosynthesis and respiration. This study examined the seasonal and interannual variations in NEE and methane emissions and possible links between the two processes in an attempt to determine the environmental controls responsible for the variations. This past summer, we collected and used NEE, methane fluxes, water table level, and meteorological data from the summer (1 May-31 August) for 2000-04, we were able to determine seasonal and interannual patterns for NEE, photosynthesis, respiration, and methane emissions. We observed that photosynthesis and respiration values become larger as the summer progressed. Methane fluxes also became greater in magnitude and variability due to higher peat temperatures and episodic events as the season progressed. Additionally, methane emissions had a positive relationship with photosynthesis and respiration, suggesting that plants exert control over methane emissions and that similar environmental factors control both respiration and methane production.

Treat*, C., J. Bubier, R. Varner and P. Crill. 2007. Time scale dependence of environmental and plant-mediated controls on CH4 flux in a temperate fen. Journal of Geophysical Research-Biogeosciences,112, G01014,1-9, doi:10.1029/2006JG000210. [Full text]

Kathryn McKain'05 has been working with thesis advisor: Dr. Steve Wofsy (Harvard University), MHC advisor: Dr. Jill Bubier, Mount Holyoke College and project mentor: Elizabeth Hammond-Pyle (Harvard University) on "Carbon Accumulation at the Harvard Forest: A Comparison of Measurement Methods and an Investigation of Spatial and Temporal Trends".
Although an abundance of data about local forest carbon cycling dynamics exists from the Prospect Hill tract, the relevance of this data depends on our ability to scale individual sites to the larger forested region. From 2000-2002, the Big Foot Project monitored an array of ecological measurement plots centered on the EMS tower over a 25 km2 area with the purpose of linking the ground-based measurements to Landsat ETM+ data and validating MODLand science products. The continued monitoring of the Big Foot plots by the Wofsy research group will provide a valuable opportunity to increase the scale of the Wofsy group’s area of study. However, an initial comparison of the Big Foot and Wofsy plots revealed that while the Wofsy plots yielded an average of 108 ± 33 MgC/ha as of 2002, the Big Foot plots yielded an average of 73± 26 MgC/ha. This discrepancy could have resulted from the different measurement methods employed by the two groups, or may reflect true spatial differences in forest composition. Whereas the Wofsy group uses fixed-radius plots, the Big Foot project used a prism method and variable-radius plots. A resurvey of the Big Foot plots using both fixed and variable radius plots has allowed for an additional comparison of the two methods. Preliminary results reveal that both methods yield equivalent biomass figures, numbers which also correspond with that calculated from the Prospect Hill tract, but not with that of the original Big Foot survey. Further investigation of the 2004 Big Foot data, including the incorporation of mortality and recruitment, will allow for the better use of existing data and thus for regional extrapolation.

Articles in refereed journals
Larmola, T., Alm, J., Juutinen, S., Koppisch, D., Augustin, J., Martikainen, P.J. & Silvola, J. 2006. Spatial patterns of litter decomposition in the littoral zone of boreal lakes. Freshwater Biology 51, 2252–2264.

Kortelainen, P., Rantakari, M., Huttunen, J.T., Mattsson, T., Alm, J., Juutinen, S., Larmola, T., Silvola, J. & Martikainen, P.J. 2006. Sediment respiration and lake trophic state important predictors for the large CO2 evasion from small boreal lakes. Global Change Biology 12, 1554–1567.

Juutinen, S., Alm, J., Larmola, T., Saarnio, S., Martikainen, P.J. & Silvola, J. 2004.
Stand-specific diurnal dynamics of CH4 fluxes in boreal lakes: Patterns and
controls. Journal of Geophysical Research 109 (D19313), doi:10.1029/2004JD004782.

Larmola, T., Alm, J., Juutinen, S., Huttunen, J.T., Martikainen, P.J. & Silvola, J. 2004. The contribution of vegetated littoral zone to winter fluxes of carbon dioxide and methane from boreal lakes. Journal of Geophysical Research 199 (D19102), doi:10.1029/2004JD004875.

Larmola, T., Alm, J., Juutinen, S., Saarnio, S., Martikainen, P.J. & Silvola, J. 2004. Floods can cause large interannual differences in littoral net ecosystem productivity. Limnology and Oceanography 49: 1896–1906.

Juutinen, S., Alm, J., Larmola, T., Huttunen, J.T., Morero, M., Martikainen, P.J. & Silvola, J. 2003. Major implication of the littoral zone for methane release from boreal lakes. Global Biogeochemical Cycles 17(4), 117, doi:10.1029/2003GB002105.

Juutinen S, Alm J, Larmola T, Huttunen J, Morero M, Saarnio S , Martikainen PJ & Silvola J. 2003. Methane (CH4) release from littoral wetlands of boreal lakes during an extended flooding period. Global Change Biology. 9 (3), 413–424.

Juutinen, S., Larmola, T., Remus, R., Mirus, E., Merbach, W., Silvola, J. & Augustin, J. 2003. The contribution of Phragmites australis litter to methane (CH4) emission in planted and non-planted fen microcosms. Biology and Fertility of Soils 38:10-14. Doi:10.1007/s00374-003-0618-1.

Larmola, T., Alm, J., Juutinen, S., Martikainen, P.J. & Silvola, J. 2003. Ecosystem CO2 exchange and plant biomass in the littoral zone of a boreal lake. Freshwater Biology 48:1295–1310.

Huttunen, J.T., Juutinen, S., Alm, J., Larmola, T., Hammar, T., Silvola, J. & Martikainen, P.J. 2003. Nitrous oxide flux to the atmosphere from the littoral zone of a boreal lake. Journal of Geophysical Research 108, doi:10.1029/2003JD002989.

Huttunen, J.T., Alm, J., Liikanen, A., Juutinen, S., Larmola, T., Hammar, T., Silvola, J. & Martikainen, P.J.. 2003. Fluxes of methane, carbon dioxide and nitrous oxide in boreal lakes and potential anthropogenic effects on the aquatic greenhouse gas emissions. Chemosphere 52: 609–621.

Juutinen, S., Alm, J., Martikainen, P.J. and Silvola, J. 2001. Effects of spring flood and water level draw-down on methane dynamics in the littoral zone of boreal lakes. Freshwater Biology 46:855–869.

Richert, M., Saarnio, S., Juutinen, S., Silvola, J., Augustin, J. and Merbach, W. 2000. Distribution of assimilated carbon in the system Phragmites australis-waterlogged peat soil after carbon-14 pulse labelling. Biology and Fertility of Soils 32:1–7.

Other Scientific Publications
Putkinen, A., Juottonen, H., Juutinen, S., Tuittila, E.-S., Fritze, H. & Yrjälä, K. 2006. Active Archaea and methane production in southern and northern boreal mire sediments. Pro Terra 29: 82–83.

Martikainen, P.J., Alm, J., Huttunen, J.T., Hyppönen, N., Jauhiainen, J., Juutinen, S., Koponen, H., Kortelainen, P., Larmola, T., Liikanen, A., Maljanen, M., Nykänen, H., Pekkarinen, N., Repo, M., Saari, A., Shurpali, N., Silvennoinen, H., Silvola, J., & Vasander, H. 2006. Greenhouse gas dynamics of terrestrial and aquatic environments: Pristine ecosystems and land-use effects, 375–381. In Kulmala, M., Lindroth, A. & Ruuskanen, T. (Eds.), Proceedings of BACCI, NECC and FCoE activities 2005. Report Series of in Aerosol Science N:o 81B, Aerosolitutkimusseura ry, Helsinki.

Juutinen, S., Alm, J., Larmola, T., Huttunen, J.T., Martikainen, P.J. & Silvola, J. 2003. Lakes and climate change; implications for CH4 emissions from littoral zone, 120–122. In Honkanen, J.O. & Koponen, P.S. (Eds.), Proceedings of Sixth Finnish Conference of Environmental Sciences. University of Joensuu, May 8–9, 2003. Finnish Society of Environmental Sciences.

Larmola, T.,Alm, J., Juutinen, S., Huttunen, J.T., Martikainen, P.J. & Silvola, J. 2003. Contribution of the littoral carbon dioxide dynamics to carbon fluxes of a boreal lake, 152–154. In Honkanen, J.O. & Koponen, P.S. (Eds.), Proceedings of Sixth Finnish Conference of Environmental Sciences. University of Joensuu, May 8–9, 2003. Finnish Society of Environmental Sciences.

Huttunen, J., Alm, J., Juutinen, S., Silvola, J. and Martikainen, P.J. 2000. Greenhouse gas fluxes in a boreal agricultural landscape. In. Pietola, L. (ed.) Soil Science in the Service of Mankind – Extended Abstracts of the 1st Finnish Soil Science Conference, Helsinki 21–22 November 2000. Pro Terra 4. University of Helsinki, 131–133.

Alm, J., Juutinen, S., Saarnio, S., Silvola, J., Nykänen, H. & Martikainen, P.J. 1996. Temporal and spatial variations in CH4 emissions of flooded meadows and vegetated hydrolittoral, 71–76. In: Laiho R, Laine J & Vasander H (eds.) Proc. of the Int. Workshop on "Northern Peatlands in Global Climatic Change", Hyytiälä, Finland 8-11. October, 1995. Publications of the Academy of Finland 1/96. VAPK.

Scientific monographs
Juutinen, S. 2004. Methane fluxes and their environmental controls in the littoral zone of boreal lakes. University of Joensuu, PhD Dissertations in Biology. No: 25. 110 p. Summary of Ph.D thesis, http://www.joensuu.fi/biologia/phd/juutinen.pdf