Large-scale phenological shifts, or timing of key life events, have been observed across many ecosystems and are consistent with changes expected with climate change. With annual temperature increases of roughly 0.2 degrees C, advancement in the timing of budburst and flowering have been widely observed. Earlier budburst and therefore longer growing seasons may have significant implications for carbon storage. Previous research has shown that increases of only one day in growing season have significantly increased forest net ecosystem productivity (NEP). However, the relationship between earlier budburst and NEP is not well established. Kellen’s research will examine the connection between phenological events at the species levels and phenological timing at the stand scale.

In contrast with the more evident relationship among increased temperature, earlier onset of budburst, and increased NEP, the connections between phenology and local, boundary-layer meteorology are much less understood. Leaf-out has been correlated with a wide variety of meteorological components including temperature, vapor pressure, and relative humidity. Kellen’s research will use precise phenological and meteorological observations to develop climate-biosphere models and determine the effects of phenological shifts on the climate-biosphere linkage so these findings can be incorporated into climate models.

Changes in timing of autumnal senescence have also been widely observed, although changes are more variable between ecosystems and more poorly understood than budburst events. Delayed leaf abscission may cause incomplete resorbtion of nutrients to storage organs as well as less N.

1. Have shifts in the timing of spring phenology occurred at Wauseon, OH in comparison to legacy data sets from the 1880's-1913? 2. How will shifts in both spring and autumn phenology impact carbon storage dynamics in northern forest ecosystems with the shift from aspen and birch dominated canopies to more heterogeneous oak and maple forests? 3. How will shifts in timing of leaf fall impact nutrient resorption dynamics? 4. What are key meteorological drivers of phenological events?

Plants respond to herbivory by evolving and inducing defenses against herbivores. Though plant defenses have been studied extensively, indirect defenses have neither been incorporated into theories of plant defense, nor investigated alongside direct defenses. Volatile organic chemicals (VOCs) are gases which can be emitted by vegetation. They play an important role in biosphere-atmosphere dynamics as well as in community interactions. VOCs have been shown to contribute to indirect plant defense against herbivores by attracting predators and parasitoids (higher trophic levels) to their herbivore hosts; however, the adaptive role of these plant signals in defense has not yet been shown convincingly. Genetic and environmental variables, as well as community context, can influence plant VOC emission. For my dissertation work, I intend to implement field and greenhouse experiments in order to gauge the relative roles of genetic variation, environmental factors, atmospheric processes, community context, geographic variation, and herbivory in influencing plant VOC emission; integrate plant VOC emission into current models of plant defense theory; and determine whether VOC emission evolved as an adaptive response to herbivore damage.

In the early 1970s the University of Michigan Biological Station initiated a series of research projects concerning the quality of the lakes in Northern Michigan under the support of the National Science Foundation through the Research Applied to National Needs (RANN) program. Dr. John Gannon joined the Biological Station's staff in 1972 and directed this program for six years. This research had significant impacts on water quality management of lakes throughout Northern Michigan. The Biological Station continued to receive grants for water quality research for several years after the RANN program had terminated.

Bird species richness and diversity in response to selective forest species modification were studied at two plots in Pellston, Emmet County, Michigan.  In one plot, three deciduous tree species were girdled to accelerate forest succession, significantly altering canopy cover and tree species composition within the plot.  The girdling of the tree species significantly reduced canopy cover of aspen and white birch compared to the reference plot.  Though the total number of birds counted per plot did not differ significantly, coniferous gleaners were significantly more common at the treatment plot and relative abundance of two species that forage primarily in deciduous trees, American Redstart and Red-eyed Vireo, differed between the treatment and control plots.  Reduced abundance of American Redstarts in the treatment plot may be related to loss of birch, a favored foraging substrate of this species, while the increased abundance of Red-eyed Vireo, a generalist in terms of tree use as a foraging substrate, in the treatment plot may reflect density compensation as a result of lower numbers of American Redstarts.