Chicago Botanic Garden

Plant Science — OUR SCIENTISTS

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Krissa Skogen, Ph.D.

Conservation Scientist
Manager, Conservation and Land Management Internship Program

Ph.D., University of Connecticut, 2008 


phone (847) 835-6919

 

Research Interests

  • Reproductive and pollination biology
  • Demography
  • Population genetics
  • Large-scale anthropogenic threats to biodiversity
  • Understanding the causes and consequences of plant population and species decline


Statement

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.

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.

Currently, I am working on a project investigating 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. Of special concern is the increased visibility of hawkmoths by their predators due to light pollution in developed areas. 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).

The results of this project will help identify the consequences of habitat fragmentation for this endemic species and may provide a better understanding of the potential impacts on similarly threatened species. Results of this work will also have direct relevance to managment of Oenothera harringtonii populations, which are state-imperiled. Oenothera harringtonii is one of 30 plants in the middle Arkansas River Valley that are the focus of current conservation attention. Because Oenothera harringtonii is an annual, it will respond rapidly to changes in habitat quality and will serve as an indicator species for other endangered plants in this region. Therefore, the results of this project may influence land use decisions in the middle Arkansas River Valley of Colorado and may provide a model for efforts to mitigate the effects of land use change on pollinators and the plants on which they depend. Lastly, because Oenothera harringtonii depends on hawkmoths for reproduction, this work will determine the extent to which nocturnal pollinators face a unique set of threats.

Publications

Skogen, K., K. H. Holsinger, and Z. G. Cardon. In review. Nitrogen deposition and the decline of a regionally threatened legume, Desmodium cuspidatum. Ecology.

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.

Guest Lectures and Seminars

Evening primroses, pollinators and practicality. July 2008. NSF Research Experience for Undergraduates Seminar, Chicago Botanic Garden.

Declining Desmodium: Multiple approaches to solving a unique conservation problem. February 2008.
Biology Departmental Seminar, Central Connecticut State University, New Britain, Conn.

Using scientific data to inform plant conservation decisions. February 2008. Guest Lecturer, Biology 327, Vascular Plants. Instructor: T. Mione. Central Connecticut State University, New Britain, Conn.


Selected Published Abstracts

(Oral presentations unless otherwise noted; * indicates presenting author.)

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.

Bradford, K.*, S. Liarakos, K. Skogen, A. Tietmeyer, P. Vitt, and K. Havens. 2001. Comparing the ability of two PCR-based techniques, RAPD and ISSR, to detect low levels of genetic diversity. 2001 Midwestern Plant Conservation Conference, Chicago Botanic Garden, Glencoe, Ill. Poster presentation.

Tietmeyer, A.*, K. Skogen*, K. Bradford, J. Taylor*, and P. Vitt. 2000. Using demographic and genetic indicators to investigate the effects of woodland restoration on the threatened Viola conspersa. Sixth Annual Janet Meakin Poor Research Symposium: 2001 Midwestern Plant Conservation Conference, Chicago Botanic Garden, Glencoe, Ill. Poster presentation.

Johnson-Groh, C.L., L. Schoessler*, C. Riedel, and K. Skogen. 2000. Underground distribution and abundance of Botrychium gametophytes and juvenile sporophytes. Symposium: Biology and Conservation of the Ophioglossaceae — A Tribute to Warren "Herb" Wagner. Botanical Society of America, Portland, Ore.

Johnson-Groh, C.L., L. Schoessler*, C. Riedel, and K. Skogen.* 1999. Underground distribution and abundance of Botrychium gametophytes and juvenile sporophytes. National Sigma Xi Annual Meeting, Minneapolis, Minn. Poster presentation.

Johnson-Groh, C.L., L. Schoessler*, C. Riedel and K. Skogen.* 1999. Underground distribution and abundance of Botrychium gametophytes and juvenile sporophytes. International Botanical Congress, St. Louis, Mo. Poster presentation.