Biomass Allocation in Leaf Litter and Resource Re-uptake in Fire-Adapted Deciduous Species in Southern Dry and Dry Mesic Forests in Southern Wisconsin
Samuel Anderson, Department of Botany, UW–Madison
Advisor: Kate McCulloh
Many of the ecosystems of southern Wisconsin evolved with the regular disturbance of fire, including prairies, oak savannas, and dry forests. Of the tree species present in these ecosystems, many are adapted to fire through traits like thicker bark, such as Quercus macrocarpa, Quercus velutina, and Carya ovata, especially when compared to fire sensitive species such as Acer negundo, Acer saccharum, and Prunus serotina. Being deciduous, these species all shed their leaves on an annual basis, but their contributions to the leaf litter and its flammability can either promote or impede fire occurrence and intensity. We are interested in studying how deciduous species present in southern Wisconsin reallocate resources from foliage as they shed their leaves and whether fire adapted species allocate more biomass and resources to shedding leaves as a means of creating a more robust fuel source as a means of promoting fire disturbance to increase their fitness.
Monitoring cold hardiness of woody perennial plants
Al Kovaleski, Department of Horticulture, UW–Madison
Cold hardiness of buds is a trait that varies throughout the dormant period (fall through spring), largely in response to weather patterns in any given year. Warmer winters can therefore lead to plants not fully realizing their maximum cold hardiness. During generally warm years, quick drops in temperature caused by shifts of the polar vortex can result in bud mortality and subsequent death of plants. To learn more about how plants are adapted to local climate, bud cold hardiness for several plant species will be measured throughout the dormant period for several years. We expect that the maximum cold hardiness will be observed in years with steady decreases in temperature during the fall and early winter. Different species will have different cold hardiness, and learning about the size of their safety margin (how much more cold hardy they are compared to minimum temperatures experienced) can help understand adaptation.
Do invasive plants provide similar seasonal effects on small mammals through seed predation?
Mark Fuka, Department of Integrative Biology, UW–Madison
Advisor: John Orrock
Invasive plants can modify ecosystem structure and biodiversity worldwide. Changes in habitat structure from the presence of invasive plants can in turn affect rodent granivory. Small mammals are able to use the vegetative cover provided by invasive plants as a refuge from predators, leading to increases in granivory within invaded habitat. Common buckthorn is an invasive woody shrub that competes with native understory vegetation. Buckthorn has a unique leaf phenology that allows it to retain its leaves late into fall and begin to leaf early in the spring. Rodents can exploit this phenology and consume high amounts of seeds late into the year within invaded habitats. While previous research has focused on fall granivory, we lack an understanding of potential rodent foraging differences during spring. Here, we propose to use a seed removal experiment within the Arboretum in both the fall and spring to examine seasonal differences in rodent granivory.
Luciann Heeg, Department of Botany, Emeritus, UW–Madison
Advisor: Ken Keefover-Ring
Chemotypes (chemical phenotypes) are determined by secondary compounds plants produce to defend against herbivores and/or to attract pollinators. Chemotypes may vary between individuals within a species. Monarda fistulosa and Thymus vulgaris, two Lamiaceae species, share five chemotypes despite life histories and geographic separation on two continents. I will investigate if these shared chemotypes are due to convergent evolution or common ancestry; I will analyze the enzymes responsible for synthesizing the main terpene in each chemotype. Leaf glandular trichomes – terpene production centers – will be isolated and processed for RNA extraction to make cDNA libraries that will be sequenced. T. vulgaris follows an epistatic cascade of chemotype dominance, and I will explore if this persists in M. fistulosa by controlled crosses between chemotypes by hand pollination in a common garden, and progeny analysis. Feeding trials with generalist and specialist herbivores will measure insect performance and survival to expose differential responses to chemotypes.
Variation in plant defense
Joseph Cammarano, Entomology and Nematology Department, University of Florida
Advisor: Phil Hahn
Intraspecific variation in floral phenotypes is a well-documented phenomenon across and within plant populations, and geographic variation has even been associated with entirely different pollinator guilds within species. Notable limitations in many of the current studies of this phenomenon, include disentangling the roles of phenotypic plasticity and non-pollinator species such as herbivores in mediating these variations. Defense against herbivory is another trait that may vary within species, and which may compromise attraction to pollinators, leading to evolutionary tradeoffs. The resource availability hypothesis posits that tradeoffs between defense against herbivory and plant growth occur across resource gradients between species, with defense being favored in low-resource environments and growth in high-resource environments, but does not address possible tradeoffs between defense and attraction of pollinators and does not necessarily address trends within species. We are addressing these ideas with common beebalm (Monarda fistulosa), a chemically defended entomophilous plant with a wide geographic range in North America, including both arid and mesic habitats.
Lost City Invasive Shrub Management
Tim Kuhman, Edgewood College
Brad Herrick and Christy Lowney, UW–Madison Arboretum
Invasive species are prevalent in southern Wisconsin. Landowners and managers allocate a lot of resources (time and money) into controlling invasive species. By studying management practices, including forestry mowing, forestry mowing followed by prescribed fire, hand clearing, and hand clearing followed by prescribed fire, we will be able to assess the efficacy of these management techniques for controlling woody invasive shrubs and allowing native herbaceous species to establish.