Krissa Skogen, Ph.D.
Teaching and Research Affiliations
Adjunct Professor, Biological Sciences, Northwestern University
Selected Professional Associations
Because plants face a multitude of threats, using a combination of scientific methodologies is often necessary to identify the causes and consequences of population and species decline. A synthetic approach allows for a more complete understanding of how anthropogenic activities may negatively impact sensitive species — including endangered, threatened, and endemic plant species. My research combines a variety of different scientific approaches to answer broad-scale conservation questions to ultimately guide policy and management decisions. In particular, my research integrates data on population genetics, demography, reproductive biology, and threats imposed by anthropogenic activities, including nitrogen deposition and habitat fragmentation.
Long-Distance Pollinator Movement – Oenothera harringtonii
This project investigates pollination, reproduction, and gene flow in the Colorado Springs evening primrose (Oenothera harringtonii, Onagraceae), a species endemic to southeastern Colorado. The flowers of Oenothera harringtonii open soon after sunset and are pollinated primarily by hawkmoths. Hawkmoths can travel up to 20 miles in just one night, and may therefore contribute significantly to long-distance gene flow among populations. These moths feed on the nectar of Oenothera flowers, which they locate by the strong fragrance produced by the flowers. This species is found in an increasingly fragmented landscape; however, little is known of the impacts that fragmentation and light pollution may have on the community of pollinators upon which it relies for reproduction and long-term population persistence. Studying populations in both fragmented/developed and unfragmented areas will allow me to determine the extent to which habitat fragmentation and light pollution may be negatively impacting both hawkmoth populations as well as populations of Oenothera harringtonii. A combination of field, greenhouse, and molecular tools are being used to understand which pollinators visit flowers, to what they are attracted (floral scent, size, nectar sugar concentration, etc.), whether plants are successfully reproducing (demographic data, hand pollinations), and to examine patterns of gene flow (microsatellite markers).
Conservation and Restoration in Changing Environments – Colorado Plateau
Together with Drs. Jeremie Fant and Dan Larkin, I am investigating plant genetic, demographic, and community dynamics in intact and restored habitats designed to guide effective and efficient restoration in the western United States. This is a region with great need for research to help guide restoration practices and policies, as demonstrated by the Great Basin Native Plant Initiative and the Colorado Plateau Native Plant Initiative. These initiatives, comprising governmental, academic and private agencies and institutions, focus on developing an adequate supply of appropriate native plant materials to facilitate the enhancement, recovery, and/or restoration of landscapes throughout the region, as well as on developing scientifically rigorous methodologies that ensure successful establishment and persistence of restored native plant habitats.
In the summer of 2010, two teams of students assessed plant and pollinator communities and phenological changes over a six-week flowering period in and around Springdale, Utah, and Montrose, Colorado, working with the Bureau of Land Management and the National Park Service (Zion National Park) to provide a baseline data for use in future projects.
Understanding Causes and Consequences of Species Decline – Desmodium cuspidatum
My previous research on the perennial legume, Desmodium cuspidatum (large-bracted tick-trefoil, Fabaceae), explored whether nitrogen deposition (acid rain) may contribute to the decline of a nitrogen-fixing plant species. This species has experienced a dramatic decline in the northeastern portion of its range in the last 30 years, from approximately 28 populations in the mid-1970s to just nine populations as of 2007. However, populations elsewhere in the species range have not declined. Interestingly, the pattern of decline in Desmodium cuspidatum is consistent with the pattern of nitrogen deposition in the United States: the highest, for the longest period of time, in the northeast. Studies of demography and reproductive biology revealed that extremely low reproductive success and recruitment (birth) rates might be limiting population growth. Furthermore, patterns of genetic diversity suggest that current populations harbor high levels of genetic diversity but might be threatened in the future if gene flow is restricted among existing populations.
Kelly Ksiazek (Northwestern University, Ph.D. expected 2016)
Matthew Rhodes (Northwestern University, M. S. expected 2013)
Rebecca Barak (Northwestern University, M. S. expected 2012) Species interactions between native forbs and invasive cheatgrass (Bromus tectorum L.) in the Colorado Plateau.
Ricardo Rivera (Northwestern University, M. S. expected 2012) Quantitative genetics in a fragmented landscape, a study of heritable floral traits in Oenothera harringtonii (Onagraceae)
Emily Booth (Northwestern University, M. S. 2011) Potential effects of climate change on Penstemon palmeri at Zion National Park, Utah, U.S.A.
Melissa Gray (Northwestern University, M. S. 2011) The effects of floral density manipulation on the pollination and reproductive success of Penstemon pachyphyllus.
Evan Hilpman (Colorado College, B.A., 2010—senior thesis co-advisor)
Genetic analysis of a Colorado endemic threatened by anthropogenic landscape alteration: Oenothera harringtonii (Onagraceae)
Logan Senack (University of Connecticutt, B.S., 2008—senior thesis co-advisor)
Seed size, germination, and the effects of herbivory in rare and common Desmodium species
(† indicates student author)
Ksiazek†, K., J. Fant and K. Skogen. 2012. An assessment of pollen limitation on Chicago green roofs. Landscape and Urban Planning. 107(4):401-408.
Skogen, K., E. Hilpman†, S. Todd†, and J. Fant. 2012. Microsatellite primers in Oenothera haringtonii (Onagraceae), and annual endemic to the shortgrass prairie of Colorado. American Journal of Botany Primer Notes and Protocols in the Plant Sciences. 99(8):e313-6.
Skogen, K., K. H. Holsinger, and Z. G. Cardon. 2011. Nitrogen deposition and the decline of a regionally threatened legume, Desmodium cuspidatum. Oecologia.165(1):261-269.
Skogen, K., L. Senack†, and K. Holsinger. 2010. Dormancy, small seed size and low germination rates contribute to low recruitment in Desmodium cuspidatum(Fabaceae). Journal of the Torrey Botanical Society. 137(4):355-365.
Tienes, M., K. Skogen, P. Vitt and K. Havens. 2010. Optimal monitoring of rare plant populations - Report for the USDA Forest Service.
Johnson-Groh, C., C.Riedel, L. Schoessler and K. Skogen. 2002. Belowground distribution and abundance of Botrychium gametophytes and juvenile sporophytes. American Fern Journal 92(2):80-92.
(oral presentations unless otherwise noted; * indicates presenting author)
Skogen, K.*, J. Fant and R. Raguso. 2012. Vagrant pollinators and fragrant plants - geographic structure in floral scent despite hawkmoth-mediated gene flow linking isloated populations. Ecological Society of America, Portland, OR.
Rivera, R.*, K. Skogen, and J. Fant. 2012. Quantitative genetics in a fragmented landscape, a study of heritabletraits in Oenothera harringtonii. Ecological Society of America, Portland, OR.
Barak, B.*, K. Skogen, and J. Fant. 2012. Assessing competitive potential of native forbs from cheatgrass-dominated habitats. Ecological Society of America, Portland, OR.
Skogen, K*, R. Raguso, J. Fant, E. Hilpman*, S. Kelso, and Q. Roberts. 2010. Fragmented fragrances: habitat modification, population structure and reproductive ecology in a rare prairie endemic, Oenothera harringtonii. Botanical Society of America, Snowbird, Utah.
Skogen, K.* and K. Havens. 2008. Demand for botanists on federal lands: Partnerships between botanic gardens and land management agencies. Botanical Society of America, Vancouver, British Columbia.
Skogen, K.* 2007. Does atmospheric nitrogen deposition contribute to the decline of a native nitrogen-fixing species, Desmodium cuspidatum? Botanical Society of America, Chicago, Ill.
Skogen, K.* 2006. Atmospheric nitrogen deposition and the decline of a nitrogen-fixing plant species. Environmental Protection Agency Science to Achieve Results Conference, Washington, D.C. Poster presentation.
Skogen, K.* and K. Holsinger. 2006. Does size matter? Genetic diversity in declining and secure populations of Desmodium cuspidatum. Botanical Society of America, Chico, Calif.
Holsinger, K.*, and K. Skogen. 2005. Plant genetic consequences of pollinator declines. National Research Council Workshop on the Status of Pollinators in North America. National Academy of Sciences, Washington, D.C.
Skogen, K.* 2005. Demography and reproductive biology of threatened populations of Desmodium cuspidatum (Fabaceae). Botanical Society of America, Austin, Tex.
Skogen, K.* 2003. Exploring causes of decline in the large-bracted tick-trefoil, Desmodium cuspidatum, (Fabaceae). 2003 National Science Foundation/New England Wildflower Society Fellowship in Conservation Biology Symposium, New England Wildflower Society, Framingham, Mass. Oral and poster presentations.
Skogen, K.* 2003. Exploring causes of decline in rare plant species. Northeast Ecology and Evolution Conference, Rutgers University, New Brunswick, N.J.
Research in the Skogen Lab combines a variety of different scientific approaches to answer broad-scale conservation questions to ultimately guide policy and management decisions. In particular, the research that my students and I conduct integrates data on demography, pollination biology, reproductive biology, population genetics, and threats imposed by anthropogenic activities, including nitrogen deposition, habitat fragmentation, and climate change. This website provides information on research conducted by myself and my students, as well as news, photos, and videos of current and previous research.
CARICE – Conservation and Restoration in Changing Environments
In the arid environments of the western States, more than one third of the habitat in the region has been degraded by invasive species and changes in fire regimes. There is a great need to learn more about how to effectively restore these ecosystems. Some of the questions our research comprises include 1) What are the ecosystems services most at risk from climate change and/or invasive species? 2) What are “appropriate” sources of plant material to use in restoration, i.e., how far can seed be moved without having negative effects on restoration outcomes? 3) What are the best management practices to meet restoration goals? and 4) How can ecosystem functions in these degraded areas be restored in the face of a changing environment? This website provides information about o-going projects that I am working on together with Jeremie Fant, Dan Larkin, Emily Yates, and Andrea Kramer and Northwestern University graduate students.
Conservation and Land Management Internship Program
The CLM Internship Program provides a unique internship experience to college graduates in which interns learn new skills, experience real-world land management and conservation, and develop connections that can lead to future employment. Each year, between 70 and 85 interns are hired to work closely with federal biologists in the Bureau of Land Management, National Park Service, USDA Forest Service, and other federal agencies. The CLM program invests in young people and builds on their enthusiasm and capacity to make a substantial contribution to protecting the environment. The majority of internships focus on projects in botany or wildlife-related fields, or combinations that have involved monitoring or assessing threatened and endangered species. Interns have also worked in fire ecology, fisheries, livestock utilization, and native plant materials. Most recently, internships have involved native seed collecting that will contribute to seed banks or restoration activities. For more information and to apply for an internship, please visit the CLM website. To learn about projects that current and previous interns have participated in, please visit the CLM Blog at www.blog.clminternship.org.