@article {KNZ001490, title = {Invasive warm-season grasses reduce mycorrhizal root colonization and biomass production of native prairie grasses}, journal = {Mycorrhiza}, volume = {22}, year = {2012}, pages = {327 -336}, abstract = {

Soil organisms play important roles in regulating ecosystem-level processes and the association of arbuscular mycorrhizal (AM) fungi with a plant species can be a central force shaping plant species\’ ecology. Understanding how mycorrhizal associations are affected by plant invasions may be a critical aspect of the conservation and restoration of native ecosystems. We examined the competitive ability of old world bluestem, a non-native grass (Caucasian bluestem [Bothriochloa bladhii]), and the influence of B. bladhii competition on AM root colonization of native warm-season prairie grasses (Andropogon gerardii or Schizachyrium scoparium), using a substitutive design greenhouse competition experiment. Competition by the non-native resulted in significantly reduced biomass production and AM colonization of the native grasses. To assess plant\–soil feedbacks of B. bladhii and Bothriochloa ischaemum, we conducted a second greenhouse study which examined soil alterations indirectly by assessing biomass production and AM colonization of native warm-season grasses planted into soil collected beneath Bothriochloa spp. This study was conducted using soil from four replicate prairie sites throughout Kansas and Oklahoma, USA. Our results indicate that a major mechanism in plant growth suppression following invasion by Bothriochloa spp. is the alteration in soil microbial communities. Plant growth was tightly correlated with AM root colonization demonstrating that mycorrhizae play an important role in the invasion of these systems by Bothriochloa spp. and indicating that the restoration of native AM fungal communities may be a fundamental consideration for the successful establishment of native grasses into invaded sites.

}, keywords = {LTER-KNZ, Arbuscular mycorrhizas, Big bluestemm, Bothriochloa bladhii, Bothriochloa ischaemum, Little bluestem, Old world bluestems, plant{\textendash}soil feedback, tallgrass prairie, Warm-season grasses}, doi = {10.1007/s00572-011-0407-x}, url = {https://link.springer.com/article/10.1007\%2Fs00572-011-0407-x}, author = {G.T. Wilson and Hickman, K.R. and Williamson, M.M.} } @mastersthesis {KNZ001394, title = {Controls on bud activation and tiller initiation in tallgrass prairie: The effect of light and nitrogen}, volume = {MS Thesis}, year = {2010}, pages = {1 -52}, school = {Oklahoma State University}, type = {M.S. Thesis}, address = {Stillwater, OK}, abstract = {

Chapter 1: Perennial grass populations in tallgrass prairie ecosystems are maintained primarily through vegetative outgrowth from their belowground bud banks. Resources in these ecosystems that have been found to limit plant productivity include nitrogen and light. I tested the Tomlinson and O\&$\#$39;Connor (2004) theory, on the interactions of two environmental cues, nitrogen and light quantity, and the roles they have on bud outgrowth and tiller initiation in six perennial grass species in two functional groups (C 3 and C 4 photosynthetic pathways). I hypothesized that (1) an interaction between nitrogen and light availability regulated bud activation and tiller emergence in the two functional groups (C 3 species and C 4 species), (2) nitrogen would have the largest effect on the activation of buds, and (3) responses to the two environmental cues would differ between the two functional groups. Environmental growth chambers were used to conduct all studies, plants received one of three NH 4 NO 3 amendments or water (control), and were placed in a light treatment chamber or a dark (control) chamber. Strong interactions between nitrogen and light influenced bud outgrowth in the C c species, but not in the C 4 species. When I assessed the impacts of nitrogen as a key cue in tiller initiation in all six species, C 3 species responded favorably to N, while C 4 species did not. These results indicate that another abiotic environmental cue may be influencing the C 4 species. The results of this study suggest that environmental cues such as these that impact belowground bud bank dynamics in the tallgrass prairie have to potential to significantly impact grassland dynamics in response to current and future global changes. Chapter 2: Three species of C 3 grasses and three species of C 4 grasses were studied to test a proposed theory (Tomlinson and O\&$\#$39;Connor 2004), to determine the role that light spectral quality (R:FR) and light quantity have on belowground bud outgrowth. I hypothesized that (1) R:FR will be an important cue in the regulation of bud bank dynamics, (2) reductions in light quantity due to litter accumulation will significantly reduce bud outgrowth, and (3) the response to the two factors will not be consistent across the two functional groups. Environmental growth chambers were used to conduct all study treatments. Plants were placed in chambers under one of three light treatments: light, reduced R:FR, or a full dark (control). To assess the effects of light availability under natural conditions, litter was used to reduce light availability in the C 4 species. Light spectral quality and quantity elicited species-specific responses in both of the functional groups. A suppression in bud outgrowth in response to R:FR reductions were observed in four of the six species. Alterations to light quantity due to litter accumulation did not reduce bud outgrowth, but a reduction in R:FR did, suggesting that light spectral quality is a more important regulator of bud dormancy and outgrowth than light intensity. Surprisingly, the response to light spectral quality and quantity were consistent across both functional groups. As we continue to seek answers to enhance rangeland quality, assessing how environmental cues are interacting may be a stronger predictor of how rangelands will respond to current and future global changes, than assessing the cues individually.

}, keywords = {LTER-KNZ}, url = {http://hdl.handle.net/11244/9577}, author = {Williamson, M.M.} } @article {KNZ001223, title = {Topsin-M: the new benomyl for mycorrhizal-suppression experiments}, journal = {Mycologia}, volume = {100}, year = {2008}, pages = {548 -554}, abstract = {

The fungicide benomyl was the most commonly used biocide for both field and greenhouse experiments in which arbuscular mycorrhizal fungal (AMF) suppression is desired. Unfortunately benomyl is no longer manufactured and therefore is not available for experimental use and no fungicide has been proposed as a successful alternative for experimentally suppressing mycorrhizal fungi. In this study we examined the potential for the fungicide Topsin M\® (topsin) to suppress mycorrhizal symbiosis in both field and greenhouse experiments. Topsin reduced AMF colonization of the obligately mycotrophic, warm-season grass Andropogon gerardii with a large and significant reduction in plant biomass production. Topsin reduced AMF colonization of the facultatively mycotrophic, cool-season grass Pascopyron smithii but did not significantly reduce biomass production. Fertilization with nitrogen and phosphorus was able to compensate for reductions in biomass due to the application of fungicide because biomass production of plants that received topsin fungicide was not significantly different from fertilized controls not receiving topsin. While we are not advocating that topsin fungicide is a universal mechanism for mycorrhizal-suppressed controls, in systems where benomyl was found to be successful topsin appears to be a useful, available and successful alternative.

}, keywords = {LTER-KNZ}, doi = {10.3852/08-024R}, url = {https://www.tandfonline.com/doi/abs/10.3852/08-024R?journalCode=umyc20}, author = {G.T. Wilson and Williamson, M.M.} }