RESEARCH

 Home

horizontal rule

 

Research Overview

    The central theme of my research program has been to explore how spatial pattern affects ecological processes, ranging from individual dispersal and movement behavior to population and community responses to habitat loss and fragmentation.   My approach has been to integrate computer simulation modeling with experimental or field investigations, usually involving either birds or insects.   Much of my recent work has been founded on applications of neutral landscape models (1,2), which provide a means of developing general, spatially explicit theory of how landscape structure, and spatial pattern more generally, affects ecological processes.  

     A recurring theme in my research has been the emergence of critical threshold responses to landscape structure.   Landscape connectivity becomes disrupted abruptly at a critical level of habitat loss and fragmentation, which ultimately depends upon the dispersal abilities of the species (3-5).  Different species thus possess different perceptions of landscape structure.  Habitat fragments also become isolated at a critical level of habitat, when the interpatch distances on the landscape rapidly increase (lacunarity thresholds).  This has implications for the ability of organisms to locate or colonize suitable habitat on the landscape.  These lacunarity thresholds may thus precipitate dispersal thresholds, in which dispersal success dramatically declines past some critical level of habitat abundance (6).  Experimental work with insects suggests that the movement or search behavior of some species may exhibit threshold responses to patch structure (7). Species that differ in their demographic potentials, as a function of their dispersal and reproductive capabilities, may exhibit an extinction threshold, where the population suddenly crashes at some critical level of habitat abundance and fragmentation severity (8).  Landscape structure can mitigate extinction risk for some species by lowering the critical habitat threshold at which these populations go extinct.  Landscape structure (the amount and spatial arrangement of habitat) also affects the ability of landscapes to function as overall population sources or sinks, as was demonstrated for various types of Neotropical migratory songbirds (9).  Landscape thresholds may also disrupt predator-prey interactions and affect the ability of natural enemies to control pest outbreaks.  Such thresholds in species interactions have important implications for conservation biological control, especially if native predators are influenced more than exotic species by habitat loss and fragmentation (10).  Greater reliance may be placed in the future on introducing exotic species for the purpose of biocontrol as agroecosystems become increasingly more fragmented.  This is not without ecological, as well as economic, costs.   My current research addresses how landscape dynamics affect extinction risk for migratory songbirds (11-13), a group of conservation concern, and involves a regional assessment of population viability for grassland birds in particular, which have exhibited steeper population declines than any other avian group in North America (14-15).

Publications cited above:

1. With, K. A. 1997. The application of neutral landscape models in conservation biology. Conservation Biology 11: 1069-1080.
2. With, K. A., and A. W. King. 1997. The use and misuse of neutral landscape models in ecology. Oikos 79: 219-229.
3. With, K. A., and T. O. Crist. 1995. Critical thresholds in species' responses to landscape structure. Ecology 76: 2446-2459.
4. With, K. A., and T. O. Crist. 1996. Translating across scales: simulating species distributions as the aggregate response of individuals to heterogeneity. Ecological Modelling 93: 125-137.
5. With, K. A., R. H. Gardner, and M. G. Turner. 1997. Landscape connectivity and population distributions in heterogeneous environments. Oikos 78: 151-169.
6. With, K. A., and A. W. King. 1999. Dispersal success in fractal landscapes: a consequence of lacunarity thresholds. Landscape Ecology 14: 73-82.
7. With, K. A., S. J. Cadaret, and C. Davis. 1999. Movement responses to patch structure in experimental fractal landscapes. Ecology 80: 1340-1353.  

8. With, K. A., and A. W. King. 1999. Extinction thresholds for species in fractal landscapes. Conservation Biology 13: 314-326.  
9. With, K. A., and A. W. King. 2001. Analysis of landscape sources and sinks: the effect of spatial pattern on avian demography. Biological Conservation 100: 75-88.  
10. With, K. A., D. M. Pavuk, J. L. Worchuck, R. K. Oates, and J. L. Fisher.  2002.  Threshold effects of landscape structure on biological control in agroecosystemsEcological Applications 12:  52-65.
11. Schrott, G. R., K. A. With, and A. W. King.  2005a.  On the importance of landscape history for assessing extinction riskEcological Applications 15:  493-506.
12. Schrott, G. R., K. A. With, and A. W. King.  2005b.  Demographic limitations on the ability of habitat restoration to rescue declining populationsConservation Biology 191181-1193.  
13. With, K. A., G. R. Schrott, and A. W. King.  2006. 
The implications of metalandscape connectivity for population viability in migratory songbirdsLandscape Ecology 21: 157-167.
14.
With, K. A., A. W. King, and W. E. Jensen.  2008.  Remaining large grasslands may not be sufficient to prevent grassland bird declinesBiological Conservation 141: 3152-3167.
15. Rahmig, C. J., W. E. Jensen, and K. A. With.  2009.  Grassland bird responses to land management in the largest remaining tallgrass prairie Conservation Biology 23:
420-432.

 

Research Projects

horizontal rule

 

Ecology of Infectious Disease:  Epidemic Waves, Landscape Heterogeneity, and Spatial Scale
Spatial structure and heterogeneity exist across a range of scales within agroecosystems, which may influence the spread of economically important plant pathogens, offering hope that widespread disease epidemics can be averted through the careful management of landscape structure and heterogeneity of agricultural systems.  We will study two model systems:  Wheat stripe rust (above left), caused by the fungus Pucinia striiformis, will be used to study the effects of landscape factors, focus size and spatial scale on the spread of disease in experimental fields.  At a broader continental scale, the spread of the newly introduced soybean rust pathogen (Phakosora pachyrhizi, above middle and right) will be related to landscape measures to determine how heterogeneity and the distribution of host species influences epidemic spread.  Finally, a simple epidemiological model will be coupled with neutral landscape models to develop general insights into how landscape abundance, spatial structure, and diversity of the host affect the spread of disease.  Issues of scale will be addressed by determining if the same relationships between landscape factors and epidemic spread are found across these two model systems which vary substantially in spatial scale.  If it is found that the effects of landscape structure and heterogeneity on disease spread are generally similar across spatial scales, then fine-scale experimental data may be useful for developing epidemiological models of disease spread at broad spatial scales.

This project is funded under the joint NIH-NSF Ecology of Infectious Disease Program.  The research team consists of Dr. Christopher C. Mundt (PI, Oregon State University), Dr. Karen Garrett (Department of Plant Pathology, KSU), Dr. James P. Stack (Department of Plant Pathology, KSU), Dr. Kimberly A. With, and Dr. Xiao-Bing Yang (Iowa State University). 
 

Publications featuring this research:
Margosian, M. L. K. A. Garrett, J. M. S. Hutchinson, and K. A. With. 2009. Connectivity of the American agricultural landscape: Assessing the national risk of disease and crop pest spread. BioScience 59: 141-151.
Skelsey, P., K. A. With, and K. A. Garrett.   Why dispersal should be maximized at intermediate scales of heterogeneityTheoretical Ecology: in press.

 

Ecosystem Thresholds and Alternate States in Great Plains Rivers and Streams:  Cascading Effects of Anthropogenic Hydrologic Disturbance

South Pawnee Fork near Larned.
Fragmentation of Kansas river networks is postulated to have affected the distribution of fishes throughout the Great Plains, leading to extirpation of native species from some rivers and the introduction and spread of exotic species in others, resulting in a strong shift in community composition that may compromise the biotic integrity and ecosystem function of these lotic ecosystems. We will utilize geomorphic, long-term (40-100 years) hydrologic, and land-use data to construct hydrologic models to describe and predict the occurrence and duration of stream flows. We will also quantify the spatiotemporal connectivity of stream networks in the Kansas portion of the Great Plains. We will analyze a substantial, georeferenced fish database, and additional data on unionid mussels derived from collections taken over the last century, and link alterations in species distributions to the changes in hydrology that have occurred, particularly in the last 40 years. The hydrologic models will also form the basis for developing a general fish dispersal model for deriving functionally based definitions of stream connectivity and for explaining and predicting species distributions within and among stream networks.

This project ran from 2005-2008 and was funded under the EPA-STAR "Understanding Ecological Thresholds in Aquatic Systems through Retrospective Analysis" Program.  The research team consists of Dr. Walter Dodds (PI, KSU Biology), Dr. Kimberly WithDr. Keith Gido (KSU Biology), and Dr. James Koelliker (KSU Biological and Agricultural Engineering).


 

Regional Assessment of Population Viability for Grassland Birds in Agricultural Grasslands

 

Landscape conversion resulting from agricultural intensification has been one of the most significant global changes of the past century, and is particularly evident in the Midwest where <2-4% of native grasslands remain.  Subsequently, grassland birds have exhibited steeper and more widespread declines than any other group of North American birds. The Flint Hills region of eastern Kansas and Oklahoma is the largest tallgrass prairie landscape left on the continent, and should thus be a population stronghold for grassland birds.  Much of the Flint Hills is managed for cattle production and agriculture,  however.  The objectives of the project were to 1) determine whether current range-management practices allow for sustainable grassland bird populations; 2) evaluate how the Conservation Reserve Program and other agricultural grasslands contribute to the conservation of grassland birds at a local scale throughout this region, 3) determine how different scenarios of land-use change (changes in range-management practices or enrollment in CRP, loss and fragmentation of remaining grassland habitat) will likely affect population viability of grassland birds in the future, 4) examine how the assessment of population status varies with the scale of analysis (from the local field scale to landscape and regional scales), and 5) evaluate whether it will be feasible to manage landscapes to reverse declining populations.  This research will thus contribute to the challenge of how to balance conservation with agricultural production in such human-dominated systems. It further fills a void in current regional approaches to the conservation of biodiversity (e.g., Gap Analysis Program) which assess only the co-occurrence of species (presence or absence), by evaluating whether regions with high species richness are actually capable of sustaining viable populations of those species.

The project ran from 2003-2007 and was funded under the USDA CSREES-NRI Managed Ecosystems Program.  The research team consisted of Dr. Kimberly With (PI), Dr. William Jensen (Postdoctoral Research Associate, Kansas State University), and Dr. Anthony King (Environmental Sciences Division, Oak Ridge National Laboratory).  
 

Publications featuring this research:
10. Klug, P. E., J. Fill, and K. A. With.  2011.  Spatial ecology of eastern yellow-bellied racer (Coluber constrictor flaviventris) and Great Plains rat snake (Pantherophis emoryi) in a contiguous tallgrass-prairie landscapeHerpetologica 67: 428-439.
9. Klug, P. E., S. L. Jackrel, and K. A. With.  2010.  Linking snake habitat use to nest predation risk in grassland birds: the dangers of shrub coverOecologia 162:803-813.
8. Klug, P. E.  2009. 
  Interactions between grassland birds and their snake predators:  the potential for conservation conflicts in tallgrass prairiePh.D. Dissertation.  Kansas State University, Manhattan, Kansas.
7.
Long, A. M., W. E. Jensen, and K. A. With. 2009. Orientation of Grasshopper Sparrow and Eastern Meadowlark nests in relation to wind direction. Condor 111: 395-399.
6. Rahmig, C. J., W. E. Jensen, and K. A. With.  2009.  Grassland bird responses to land management in the largest remaining tallgrass prairie Conservation Biology 23:
420-432. 
5. With, K. A., A. W. King, and W. E. Jensen.  2008.  Remaining large grasslands may not be sufficient to prevent grassland bird declinesBiological Conservation 141: 3152-3167.
4. Frey, C. M., W. E. Jensen, and K. A. With. 2008. Topographic patterns of nest placement and habitat quality for grassland birds in the Flint Hills.  American Midland Naturalist 160: 220-234.
3. With, K. A.  2007.  A regional assessment of agricultural land use on grassland birds.  NRI Research Highlights, No. 1.  United States Department of Agriculture, Cooperative State Research, Education and Extension Service, National Research Initiative, Washington, D.C.
2. Frey, C. M.  2006. 
Topographic variation in habitat quality and settlement patterns of grassland passerines in the Flint Hills.  M.S. Thesis.  Kansas State University, Manhattan, Kansas.
1. Jung, C. R. I.  2006. 
Variation in the suitability of grassland management regimes for nesting grassland birds in the Flint Hills.  M.S. Thesis.  Kansas State University, Manhattan, Kansas.

Research in the news:
Disappearing Birds (CJ Online: Birds Declining in Flint Hills) (Topeka Capital-Journal, 22 March 2009)
Grassland Birds in Flint Hills Region of Kansas, Oklahoma Face Population Decline in Spite of Large Habitat Area (K-State News Release, 3 March 2009)


 
Assessment of Extinction Risk in Dynamic Landscapes

Landscapes are being transformed faster than ever before in human history, which requires that extinction risk be assessed in a dynamic landscape context. This research will contribute to a general understanding of how chronic habitat loss and fragmentation affect extinction risk for migratory songbirds, a group of conservation concern. This analysis will identify critical levels of disturbance, and the specific components of the disturbance regime, that drive sensitive species to extinction on landscapes. Of particular interest will be the occurrence of extinction thresholds, where small changes in landscape structure can have unexpected consequences for population persistence. The life-history traits that predispose species to be sensitive to particular forms of disturbance architecture will be identified by this approach. The combination of landscape and life-history traits will provide simple criteria that can be used by resource managers in a screening-level assessment of extinction risk. The analysis of extinction risk in dynamic landscapes will also permit an assessment of whether habitat restoration or other landscape management can reduce extinction risks or reverse population decline, and the magnitude of landscape change that might be required.

This project ran 2001-2004 and was funded under the EPA-STAR Wildlife Risk Assessment Program.  The research team consisted of Dr. Kimberly With (PI),  Dr. Gregory Schrott (Postdoctoral Research Associate, Kansas State University), and Dr. Anthony King (Environmental Sciences Division, Oak Ridge National Laboratory). 

Publications featuring this research:
5. With, K. A., G. R. Schrott, and A. W. King.  2006.  The implications of metalandscape connectivity for population viability in migratory songbirdsLandscape Ecology 21: 157-167.
4. With, K. A.  2005. 
Case study:  Assessing extinction risk in migratory songbirds:  the need for landscape-based demographic models.  Pp. 449-453 in Principles of Conservation Biology, 3rd edition (M. J. Groom, G. K. Meffe, C. R. Carroll, and contributors).  Sinauer, Sunderland, MA.
3. Schrott, G. R., K. A. With, and A. W. King.  2005b.  Demographic limitations on the ability of habitat restoration to rescue declining populationsConservation Biology 191181-1193.  
2. Schrott, G. R., K. A. With, and A. W. King.  2005a.  On the importance of landscape history for assessing extinction riskEcological Applications 15:  493-506.
1. With, K. A.  2004.  Metapopulation dynamics:  perspectives from landscape ecology.  Pp. 23-44 in Metapopulation Dynamics:  Ecology, Genetics, and Evolution of Metapopulations (I. Hanski and O. E. Gaggiotti, editors).  Academic Press, San Diego, CA. 

Research in the news:
Kansas State University News Release (27 May 2005)
Will Songbirds Find a Home on the Range? (K-State Perspectives, June 2002)

 

Effect of Habitat Fragmentation on Biodiversity and Species Interactions--Experimental Landscape Ecology
 

An Experimental Model Landscape System (EMLS), inspired by neutral landscape models, was established in the field to assess how habitat  connectivity affects species interactions (predator-prey and host-parasitoid relationships) and the structure and dynamics of terrestrial arthropod communities that naturally colonized clover habitat in this agroecosystem.  This research is being done in collaboration with Dr. Daniel Pavuk of the Department of Biological Sciences at Bowling Green State University, and was supported by the National Science Foundation.  This funding and supplemental grants from the NSF Research Experience for Undergraduates Program also enabled the participation of more than a dozen students in ecological research. 

The first publication (With et al. 2002) to emerge from this project reports on how thresholds in landscape structure (lacunarity thresholds) affect the ability of natural enemies to track the distribution of insect pests (biocontrol thresholds).  Landscape thresholds precipitate similar thresholds in the distribution of aphid populations, which become isolated (fragmented) when clover habitat falls below 20%.  An exotic coccinellid (Harmonia axyridis) that was introduced specifically for the biocontrol of pea aphids was able to track this threshold in the distribution of its aphid prey, but an indigenous coccinellid (Coleomegilla maculata) was unable to do so.   An analysis of movement responses to patch structure at different scales revealed that the biocontrol agent was much more mobile, exhibiting a greater propensity to move within and between landscape plots, than the indigenous coccinellid.  The native predator was thus more sensitive to habitat fragmentation and was unable to track aphid distributions when they became scarce and patchily distributed (i.e., <20% habitat).   If native predators are generally more sensitive to habitat fragmentation than exotic species, our study suggests that we may become increasingly dependent upon the introduction of exotic biocontrol agents that are better able to track pest populations below the biocontrol threshold as agroecosystems become progressively more fragmented.   This will obviously incur great ecological, as well as economic, costs.  In addition to economic thresholds, there are also ecological thresholds that must be surmounted for successful biocontrol.  

Landscape ecology is defined as the study of how spatial pattern affects ecological process.  Thus, this project also demonstrates how landscape ecology can profitably be applied at finer spatial scales to test hypotheses regarding how landscape structure affects predator movement responses to prey distributions, species interactions, and community dynamics.
 

Aerial view of the 4-ha Experimental Model Landscape System (EMLS) located north of the Bowling Green State  University campus in Ohio.  Each plot is a 16 x 16-m"landscape" in which red clover (Trifolium pratense) has been seeded in a specified fractal pattern to produce complex habitat distributions across a range of fragmentation severity.  Plots represent a replicated series of habitat abundance (10,20,40,50,60 and 80% clover) and fragmentation (H = 0.0, fragmented vs. H = 1.0, clumped).  White area within plots is compacted soil, which contrasts with the darker soil between plots that was plowed just prior to taking this photo.

Publications featuring this research:
With, K. A., and D. M. Pavuk.  2012.  Direct versus indirect effects of habitat fragmentation on community patterns in experimental landscapes. Oecologia 170: 517-528.
With, K. A., and D. M. Pavuk.  2011.  Habitat area trumps fragmentation effects on arthropods in an experimental landscape system. Landscape Ecology 26: 1035-1048.
With, K. A., D. M. Pavuk, J. L. Worchuck, R. K. Oates, and J. L. Fisher.  2002.  Threshold effects of landscape structure on biological control in agroecosystemsEcological Applications 12:  52-65. 

horizontal rule