Current Research Projects
Phenological Drivers of Herbivore Abundance
We have monitored arthropod abundance in ten Ligusticum populations for the last seven years. From these data, we can see that yearly variation in the abundance of aphids (Aphis helianthi) is not a function of any of the usual suspects: host plant phenology or abundance, temperature or precipitation. Instead, years of greater aphid abundance are associated with later snowmelt dates. When the snow melts earlier or later from a site, many factors could change that would effect aphid abundance. One possible driver of the snowmelt-aphid relationship are predators known as lygus bugs. These hemipterans achieve their peak abundances in years with earlier snowmelt dates. When snowmelt comes later, soils around the host plant will stay moist. This moisture likely effects plant physiology and perhaps phloem sap quality for aphids. A recently funded grant (2017) will allow us to experimentally test for these mechanisms. The funding will also allow us to replicate the elevation gradient in the ten monitoring populations to ten new sites.
We have monitored arthropod abundance in ten Ligusticum populations for the last seven years. From these data, we can see that yearly variation in the abundance of aphids (Aphis helianthi) is not a function of any of the usual suspects: host plant phenology or abundance, temperature or precipitation. Instead, years of greater aphid abundance are associated with later snowmelt dates. When the snow melts earlier or later from a site, many factors could change that would effect aphid abundance. One possible driver of the snowmelt-aphid relationship are predators known as lygus bugs. These hemipterans achieve their peak abundances in years with earlier snowmelt dates. When snowmelt comes later, soils around the host plant will stay moist. This moisture likely effects plant physiology and perhaps phloem sap quality for aphids. A recently funded grant (2017) will allow us to experimentally test for these mechanisms. The funding will also allow us to replicate the elevation gradient in the ten monitoring populations to ten new sites.
Ecological Determinants of Medicinal Activity
Humans depend on medicinal plants. Many people still rely on traditional herbal medicine and pharmaceutical drug discovery also uses the compounds found in nature. Plant defense theory predicts that plants in the shade will be better defended than plants in higher light environments. Since plant defense compounds are frequently responsible for medicinal activity, this suggests that plants in the shade will be a richer source for the bioactive compounds used in herbal medicine and drug discovery. Our previous work has shown that extracts of Ligusticum from the shaded aspen understory have greater antibacterial activity than extracts from plants in open meadows. We are currently collaborating with analytical chemists from the UCCS Department of Chemistry to apply a quantitative HPLC method to assess this variation. We will be looking for variation in three important secondary compounds with light environment.
Humans depend on medicinal plants. Many people still rely on traditional herbal medicine and pharmaceutical drug discovery also uses the compounds found in nature. Plant defense theory predicts that plants in the shade will be better defended than plants in higher light environments. Since plant defense compounds are frequently responsible for medicinal activity, this suggests that plants in the shade will be a richer source for the bioactive compounds used in herbal medicine and drug discovery. Our previous work has shown that extracts of Ligusticum from the shaded aspen understory have greater antibacterial activity than extracts from plants in open meadows. We are currently collaborating with analytical chemists from the UCCS Department of Chemistry to apply a quantitative HPLC method to assess this variation. We will be looking for variation in three important secondary compounds with light environment.
Community-Level Effects of Forest Disturbance Events
Many areas around the world have experienced large-scale forest disturbance events. In Colorado, we have the impacts of sudden aspen decline (SAD), beetle kill of spruce or pine and fires. These events alter many abiotic factors in the forest understory, with likely consequences for plants and the herbivores that consume those plants. I am interested in how changes in light and temperature could influence the herbivore community in the understory of large dieback events.
Many areas around the world have experienced large-scale forest disturbance events. In Colorado, we have the impacts of sudden aspen decline (SAD), beetle kill of spruce or pine and fires. These events alter many abiotic factors in the forest understory, with likely consequences for plants and the herbivores that consume those plants. I am interested in how changes in light and temperature could influence the herbivore community in the understory of large dieback events.