Research
My research has taken me to the Mediterranean ecosystem of California, an artificial rainforest in Arizona, the tropical rainforests of Costa Rica, hardwood forests in New Hampshire, the alpine of Colorado, and most recently the Sentenac Cienega in southern California. This work has examined the impact of global change on ecosystem processes and communities.
Upcoming: Characterizing vegetation communities and long-term changes at the Sentenac Cienega
The effect of shrub microhabitats on alpine plant community composition and function
Topography and structure-forming species (e.g. trees, shrubs) promote microhabitats, small-scale variations across a landscape. Shrub microhabitats are becoming more prevalent in alpine and arctic areas as warming temperatures lead to shrub encroachment.
I established plots across N- and S-facing aspects at Niwot Ridge, in the Front Range of CO, on the lee of shrubs and in open areas. I found that shrubs increased soil moisture early in the season, likely due to snow accumulation. Additionally, I found evidence for thermal amelioration by shrubs (lower daily temperature swings, lower maximum temperatures, lower mean temperatures, and higher minimum temperatures), suggesting the potential for shrubs to provide microrefugia under climate change.
In accordance with those findings, I expected that shrubs would foster less stress-tolerant species and I found this to be the case, regardless of aspect. This suggests that shrubs have a filtering effect on the community, providing optimal conditions for less stress-tolerant species.
Topography and structure-forming species (e.g. trees, shrubs) promote microhabitats, small-scale variations across a landscape. Shrub microhabitats are becoming more prevalent in alpine and arctic areas as warming temperatures lead to shrub encroachment.
I established plots across N- and S-facing aspects at Niwot Ridge, in the Front Range of CO, on the lee of shrubs and in open areas. I found that shrubs increased soil moisture early in the season, likely due to snow accumulation. Additionally, I found evidence for thermal amelioration by shrubs (lower daily temperature swings, lower maximum temperatures, lower mean temperatures, and higher minimum temperatures), suggesting the potential for shrubs to provide microrefugia under climate change.
In accordance with those findings, I expected that shrubs would foster less stress-tolerant species and I found this to be the case, regardless of aspect. This suggests that shrubs have a filtering effect on the community, providing optimal conditions for less stress-tolerant species.
The finding that shrubs provide conditions favorable for less stress-tolerant species suggests that shrubs could act as stepping stones for subalpine species. With warming, subalpine species, like the shrubs that I'm studying, are predicted to move uphill. This movement could be hastened by the presence of microhabitats that have suitable conditions in the present. I established plots across which I planted over 5,000 seeds of four subalpine species. Additionally, I removed neighbors in half of the plots to understand how subalpine establishment might be influenced by the existing alpine plant community. As luck would have it, only one of the four subalpine species had high enough germination rates for analysis. I found that that this species, Erigeron glacialis, had higher survival in shrub plots regardless of neighbor removal. This provides support for the notion that shrubs could act as stepping stones for subalpine establishment in the alpine.
Previous Work (see Publications)
- In addition to my shrub microclimate work, I have researched plant-microbial interactions at Niwot Rdige, CO. I studied the role of host plant phylogenetic distance in shaping the root endosphere and found that host plant relatedness was a stronger driver compared to soil properties. Additionally, I examined the potential for a mediating effect of the plant community on soil microbial response to simulated nitrogen deposition. We found that the soil microbial community responded directly to shifts in nitrogen availability rather than experiencing indirect effects via the plant community.
- As a collaboration with Dr. Elsa Cleland, I leveraged an existing experimental framework in the White Mountains near Bishop, CA, to examine the impact of warming and shrub encroachment on the decomposition rates of two native species, a shrub and a cushion plant. We found that warming and shrub encroachment decreased decomposition likely due to a decline in soil moisture and the presence of phenolics in the shrub litter, respectively.
- While working under the direction of Dr. Ruth Yanai in the Bartlett, Jeffers Brook, and Hubbard Brook Experimental Forests, I led the deployment of 960 tea bags as part of the TeaComposition initiative (an International Long Term Ecological Research study on global decomposition rates) established by Dr. Ika Djukic. The 12 month retrieval showed that litter quality was the key driver of decomposition.