My current research combines newly-collected data with long-term bee abundance and climate data to examine the drivers and potential consequences of pollinator and plant community variation across space and time. In particular, I make used of long-term bee abundance data from the Sevilleta Long-Term Ecological Research (SEV-LTER) Program, building off of work begun by Dr. Karen Wright in 2002, to examine the following topics:
Trait-mediated effects of climate change on bees, and their consequences for plants Recent studies have documented large declines in terrestrial arthropod biodiversity, some of which may be induced by climate change. Trait-based studies could advance much-needed understanding of both the causes and consequences of these declines. My work combines a novel set of bee trait measurements with SEV-LTER bee abundance and climate data to build generalizable predictions about how bee assemblages and their pollination services will respond to climate change. At the bee population level, I am examining which physiological, morphological, or behavioral traits predict bee population sensitivity to changes in climate mean and variability. Then, at the community level, I am considering how bee traits related to climate sensitivity and pollination have changed over time in concert with climate change, with the goal of predicting pollination services under future climate scenarios.
Plant phenology, bee phenology, and climate change Climate change could bring about phenological mismatches between plants and pollinators, with detrimental effects on their populations. However, we still lack evidence of the extent to which such mismatches are likely to occur. As part of a collaborative effort with researchers from the University of New Mexico and the University of California, Riverside, I am using SEV-LTER data to consider whether the phenological overlap of bees and their host plants has changed over time, and to assess the potential for climate change-induced phenological mismatches between bees and plants.
Predicting the consequences of climate-induced ecosystem state transitions for bee assemblages and their seasonality Drylands worldwide are experiencing ecosystem state transitions, the expansion of some ecosystem types at the expense of others. To better understand how future ecosystem state transitions may influence bees, we compared bee assemblages and their seasonality among sites that represent three dryland ecosystem types (and two ecotones) of the southwestern U.S. Our work, published here, found that bee abundance, composition, and diversity differed among ecosystem types, indicating that future state transitions could alter bee assemblage composition in our system. We also found strong seasonal bee species turnover, suggesting that bee phenological shifts may accompany state transitions. Predicting the consequences of global change for bee assemblages thus requires accounting for variation both within years and among ecosystems.
Previous Projects My previous research, conducted at the Rocky Mountain Biological Laboratory, examined how plant-fungal interactions may structure ecological communities and respond to climate change.
Plant-fungal interactions and climate change Altitudinal gradient studies and warming experiments can both increase understanding of climate change effects on species interactions, but few studies have used both together to improve predictions. We examined whether plant-fungal symbioses responded similarly to altitude and 23 years of experimental warming. Leaf-associated fungi were more sensitive to climate and experimental warming than root-associated fungi, suggesting greater potential susceptibility to climate change, and fungal responses to warming differed among host plants. Fungi had divergent responses to elevation versus warming, suggesting that altitude does not always serve as an adequate proxy for warming effects on fungal symbionts of plants. This work, published here, was part of a broader NSF-funded project examining the potential for climate change to disrupt plant-fungal interactions.
Plant-fungal interactions and plant coexistence How do plant-microbe interactions influence plant species coexistence? Using observational and experimental approaches, we explored whether the presence of a fungal endophyte (genus Epichloë) may enable the coexistence of two congeneric grass species by shifting the niche of its partner plant, marsh bluegrass (Poa leptocoma) relative to a closely related but Epichloë-free grass species, nodding bluegrass (Poa reflexa). Our results, published here, indicated that the two grasses were less likely to co-occur than expected by chance, with P. leptocoma growing in wetter microsites than P. reflexa. Epichloë presence constrained the germination and early survival of P. leptocoma to wetter microsites, but benefited host plant growth. Differential effects of endophyte symbiosis on different host life history stages may thus contribute to niche partitioning between the two grasses, potentially facilitating their coexistence. A subsequent greenhouse experiment tested whether endophyte symbiosis promotes host fitness under flooded conditions, and was published here.