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Influence of resource availability on Juniperus virginiana expansion in a forest–prairie ecotone
Ganguli, A., D. Engle, P. Mayer, AND L. Salo. Influence of resource availability on Juniperus virginiana expansion in a forest–prairie ecotone. Ecosphere. ESA Journals, 7(8):e01433, (2016).
Managing invasive species requires a clear understanding of the factors favoring invasion in various habitats. Eastern Redcedar (Juniperus virginiana) is an aggressively invasive tree species that displaces grasses in prairie and old-field ecosystems. This species was once controlled by fire. Today, this species grows in monocultures that reduces local biodiversity, consumes significant groundwater, and creates significant fire hazard and potential air pollution risk. This study demonstrated that tallgrass prairie is the most susceptible habitat type to invasion and identified soil type as the major limiting factor in Eastern Redcedar invasion. Thus, management of this species will likely be most effective when focusing on tall grass habitats and areas where soils are most favorable for redcedar growth.
Despite being native to the United States, Juniperus virginiana has rapidly expanded in prairie ecosystems bringing detrimental ecological effects and increased wildfire risk. We transplanted J. virginiana seedlings in three plant communities to investigate mechanisms driving J. virginiana expansion following removal of fire, the factor historically limiting range expansion of this fire-intolerant species. We evaluated J. virginiana seedling survival and seedling growth, two important phases in woody plant expansion, relative to two belowground resource factors, soil texture (including clay content, an index of plant available soil water) and plant available nitrogen (PAN), and an aboveground factor, photosynthetic active radiation (PAR). In three plant communities associated with an oak forest-tallgrass prairie ecotone, we transplanted two-year-old J. virginiana seedlings in a systematic grid design and measured J. virginiana seedling survival and growth 8, 20, and 30 months following transplant. We also measured soil texture, PAN, and PAR in 1-m2 quadrats centered on each transplanted seedling. We employed path analysis at two spatial scales (144 m2 and 2916 m2) to compare the role of resource factors in seedling growth and survival. Soil clay content emerged as the most important resource factor explaining much of the variation in J. virginiana seedling survival and seedling growth, suggesting that soil texture and other belowground factors modulate the rate of J. virginiana expansion within the oak forest-tallgrass prairie ecotone. Accurate prediction of range expansion by J. virginiana and subsequent management may be improved by identifying regions with soils most suitable for invasion.