Joshua Halman (BS-UVM ‘01, MS-NR ’07, PhD-NR ’13) spent a decade studying forest and tree health in the University of Vermont Rubenstein School. As a forest health specialist since February 2015 with the Vermont Department of Forests, Parks and Recreation, he applies his research expertise to the state’s forest monitoring projects.
“In addition to learning about tree physiology and forest health, my time at UVM helped me develop skills in study design and effective communication,” shares Josh. “I routinely use all of these skills in various arrangements on a daily basis, whether explaining tree health concerns to a landowner or helping create a protocol for emerald ash borer detection.”
At the Vermont Department of Forests, Parks and Recreation office in Essex Junction, VT, Josh manages several different projects. He could be fielding shade-tree inquiries from landowners one day, developing sampling protocols for insect surveys another day, or assessing fall foliage progression yet another day.
His major duties include coordinating spring and fall forest phenology monitoring efforts, coordinating the state’s Forest Inventory and Analysis (FIA) program, developing surveys in high-risk areas for invasive insects, managing and analyzing forest health data, and providing educational outreach in forest health to the public.
In particular, the state’s phenology project tracks progression of important seasonal changes in forest trees. With sugar maple, in particular, over the last 25 years, the Department has monitored different stages of bud development in the spring and expression of fall color and leaf drop in the fall.
“This has allowed us to generate a long-term record that not only indicates whether or not the timing of spring and fall events is changing, but also allows us to identify changes in growing season length,” explains Josh. “In the context of a changing climate, this is obviously an important dataset for studying regional patterns. Indeed, we have found peak fall color is occurring later over the 25-year sampling period, and the growing season is becoming longer as well.”
Research roots
Josh’s graduate research evolved out of a long-time collaboration between the Rubenstein School and the USDA Forest Service Northern Research Station. His advisor, Paul Schaberg, Forest Service scientist and adjunct faculty member in the Rubenstein School, and Gary Hawley, Rubenstein School research associate, served as mentors and colleagues. Josh acknowledges Paul and Gary, for their direct impact on his education and career path.
“In addition to the myriad research projects and experiences they provided, they also stressed the importance of becoming a compelling communicator,” he states. “Over the years, they impressed upon me that even the most groundbreaking study means relatively little if the findings and context can’t be conveyed to others. I think about this often now because of the variety of audiences I speak with, and it is one of the more important lessons I learned at UVM.”
His master’s research took him to Hubbard Brook Experimental Forest in New Hampshire where he examined the physiological response of red spruce trees to long-term calcium fertilization. Decades of calcium additions to an entire watershed have brought forest soils back to pre-pollution levels of calcium, which was largely leached out as a result of chronic acid deposition.
The research team analyzed needles from spruce trees on the calcium-addition watershed and discovered greater concentrations of sugars that contribute to cold tolerance and higher antioxidant activity compared to foliage from the unfertilized reference watershed.
“In short,” sums up Josh, “trees growing in soils with pre-pollution levels of calcium were better equipped to deal with the stresses of winter conditions.”
As a doctoral student, Josh continued to examine the influence of calcium-availability on the response of forest trees to stresses.
He explored the capacity of paper birch trees in Vermont to recover from ice-storm damage. Birches growing on soils with higher calcium levels were able to rebuild their crowns, he determined, and they accrued greater diameter growth following ice storm breakage than did trees on soils with lower calcium levels.
Returning to Hubbard Brook, Josh and his colleagues turned their attention to the influence of calcium and aluminum additions on sugar maple and American beech. Josh found that sugar maple roots, shoots, and foliage were significantly more stressed by addition of aluminum (a toxic element to plants that is mobilized by acid deposition) than by calcium additions or control conditions. Calcium additions favored growth of mid-canopy sugar maple trees to out-grow beech, while additions of aluminum resulted in greater growth of beech over maple.
“This response suggests that American beech – a species thought to be aluminum tolerant – was able to capitalize on aluminum-stressed sugar maple,” notes Josh. “Beech actually produced its highest growth rate on aluminum-addition sites compared to other treatments.”
Josh lives in Jericho with his wife Lindsey, a teacher at Essex Middle School, and their daughter Aila. When not in the woods (and sometimes even then!), Josh is always on the look-out for new places to fly fish. He plays mandolin with a number of local acts and enjoys hiking and cross-country skiing with his family.