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Arbuscular mycorrhizal fungi and understory plant diversity in Wisconsin oak savannas.
Landis, Frank*,1, Givnish, Thomas1, Gargas, Andrea1, 1 University of Wisconsin-Madison, Madison, WI
ABSTRACT- Arbuscular mycorrhizal fungi (Glomeromycota, AMF) are ubiquitous in most terrestrial plant communities, and a number of researchers have shown that AMF can affect plant community structure and composition in different systems. Furthermore, glomalean fungi are obligate biotrophs, obtaining all their carbohydrates from their photosynthetic partners. Combining these facts creates an interesting question: How do AMF influence plant community composition and structure along steep light gradients? This situation exists in Wisconsin oak savannas, which are among the most species-rich and endangered plant communities in the upper Midwest. Scattered savanna oaks create steep light gradients over short distances, and recent research has shown that these light gradients, along with soil texture patterns, influence the distribution of understory plant species. Our study looks at the relationships between plant diversity, glomalean diversity and light, and soil N and P concentrations. One hundred eight 1-m2 plots were established in three remnant oak savannas in Wisconsin. Plant species and percent cover were tallied repeatedly, and soil cores were taken to determine the species of AMF present. Soil nutrient levels were measured, and hemispheric photography was used to estimate the light regime. Data were processed via NMS ordination and a simple structural equation model. The results show a positive correlation between AMF and plant species richness, and surprising interactions among the abiotic factors, AMF composition, and plant community composition.
Key words: community ecology, environmental gradients, arbuscular mycorrhizae, oak savanna