@article {KNZ001725, title = {Density dependence of herbivorous central stoneroller Campostoma anomalum in stream mesocosms}, journal = {Ecology of Freshwater Fishes}, volume = {26}, year = {2017}, pages = {313-321}, abstract = {

Herbivorous fish can have strong effects on stream ecosystem function by consuming primary producers and excreting limiting nutrients, but it is unclear whether they are resource limited. Thus, understanding factors regulating abundance of these fish might help predict ecosystem function. We used stream mesocosms to test whether populations of central stoneroller Campostoma anomalum exhibit density dependence across a range of typical densities and resource abundance found in Great Plains streams. We predicted that incrementally increasing stocking biomass from 3\·7 to 24\·9\ g\·m\−2 would reduce standing stocks of resources resulting in lower growth of stocked fish. Fish growth (over 41\ days) was compared to initial stocking biomass and primary production as well as standing stocks of algae and invertebrates using regression analysis. Mean growth of individuals was negatively associated with stocking biomass (math formula\ =\ 0\·55; P\ =\ 0\·02), as predicted. Contrary to our prediction, increases in fish biomass led to increased primary productivity (math formula\ =\ 0\·31, P\ =\ 0\·07), but resulted in no relationship among algal filament lengths (math formula\ =\ 0\·00; P\ =\ 0\·34), algal biomass (math formula\ =\ 0\·12; P\ =\ 0\·19) or invertebrate biomass (math formula\ =\ 0\·03; P\ =\ 0\·30). Thus, density dependence occurred without an apparent reduction in food resources. We hypothesised that stoneroller growth was possibly limited by competition for high-quality algae or invertebrates, or behavioural interactions causing interference competition.

}, keywords = {LTER-KNZ, Herbivory, Primary production, Resource limitation, stream fish}, doi = {10.1111/eff.12277}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/eff.12277}, author = {Pennock, C.A. and K. B. Gido} } @article {KNZ001758, title = {Grazing by bison is a stronger driver of plant ecohydrology in tallgrass prairie than fire history}, journal = {Plant and Soil}, volume = {411}, year = {2017}, pages = {423-436}, abstract = {

Background and Aims: Fire and grazing are important disturbances in grasslands, yet we know little about how they impact a variety of plant physiological processes such as plant ecohydrology. Here, we assessed the impact of fire history and grazing by Bison bison on the source of water uptake and niche overlap in common grassland species at the Konza Prairie Biological Station, a temperate mesic grassland located in northeastern Kansas, USA. Methods: We used the stable isotopic signature of soil and xylem water to evaluate water uptake in Andropogo n gerardii, Vernonia baldwinii, Amorpha canescens,and Rhus glabra within varying grazing (grazed, ungrazed), fire (0,1,2 or 3 years since last burn), topography (upland, lowland), and month (July, August) contrasts over 3 years (2013\–2015). Results: The presence of grazers, not fire history, altered water uptake patterns in these common grassland species. Particularly, grazing increased the proportion of shallow water utilized by A. gerardii and R. glabra, reducing niche overlap with other co-occurring species. However, these responses varied intra-annually and were often modulated by topography. Conclusions: These results suggest that grazing can alter aspects of grassland ecohydrology at small scales, which may extend to impact community and ecosystem processes at larger spatial scales.

}, keywords = {LTER-KNZ, fire, Herbivory, Mesic grassland, Niche overlap, Source water, Stable isotopes}, doi = {10.1007/s11104-016-3048-1}, url = {https://link.springer.com/article/10.1007\%2Fs11104-016-3048-1}, author = {O{\textquoteright}Keefe, K. and Jesse B. Nippert} } @article {KNZ001768, title = {High dissimilarity within a multiyear annual record of pollen assemblages from a North American tallgrass prairie}, journal = {Ecology and Evolution}, volume = {6}, year = {2016}, pages = {5273 - 5289}, abstract = {

Grassland vegetation varies in composition across North America and has been historically influenced by multiple biotic and abiotic drivers, including fire, herbivory, and topography. Yet, the amount of temporal and spatial variability exhibited among grassland pollen assemblages, and the influence of these biotic and abiotic drivers on pollen assemblage composition and diversity has been relatively understudied. Here, we examine 4 years of modern pollen assemblages collected from a series of 28 traps at the Konza Prairie Long-Term Ecological Research Area in the Flint Hills of Kansas, with the aim of evaluating the influence of these drivers, as well as quantifying the amount of spatial and temporal variability in the pollen signatures of the tallgrass prairie biome. We include all terrestrial pollen taxa in our analyses while calculating four summative metrics of pollen diversity and composition \– beta-diversity, Shannon index, nonarboreal pollen percentage, and Ambrosia:Artemisia \– and find different roles of fire, herbivory, and topography variables in relation to these pollen metrics. In addition, we find significant annual differences in the means of three of these metrics, particularly the year 2013 which experienced high precipitation relative to the other 3 years of data. To quantify spatial and temporal dissimilarity among the samples over the 4-year study, we calculate pairwise squared-chord distances (SCD). The SCD values indicate higher compositional dissimilarity across the traps (0.38 mean) among all years than within a single trap from year to year (0.31 mean), suggesting that grassland vegetation can have different pollen signatures across finely sampled space and time, and emphasizing the need for additional long-term annual monitoring of grassland pollen.

}, keywords = {LTER-KNZ, fire, grassland, Great Plains, Herbivory, Pollen, Tauber traps}, doi = {10.1002/ece3.2259}, url = {https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.2259}, author = {Commerford, J.L. and McLauchlan, K.K. and Minckley, T.A.} } @article {KNZ001695, title = {Belowground bud bank response to grazing under severe, short-term drought}, journal = {Oecologia}, volume = {178}, year = {2015}, pages = {795-806}, abstract = {

While the effects of drought and grazing are often studied separately, these disturbances co-occur in grasslands worldwide and interactively influence population, community, and ecosystem processes. The effects of drought and grazing on the belowground bud bank may dictate the trajectory of community recovery because new shoots arise from belowground buds after disturbance in perennial grasslands. We therefore investigated the separate and interactive effects of severe drought and grazing on the belowground bud bank and aboveground vegetation in the tallgrass prairie of northeast Kansas, USA. Contrary to our expectations, we observed changes in community structure and declines in species richness both above and below ground in response to drought and grazing. We also hypothesized that drought would reduce bud bank density of all taxonomic groups, but found that grass bud and shoot densities remained constant across all drought and grazing treatment combinations. While sedge and forb bud and shoot densities were reduced by drought, only sedge bud density declined to a greater extent when grazed under drought conditions. Live rhizome biomass did not vary by treatment and was highly correlated with bud bank density, suggesting that bud demography is tightly linked to the production and senescence of rhizomes. Despite the effects of drought and grazing on aboveground net primary productivity and community structure, our work suggests that grasses stabilize tallgrass prairie plant communities because their rhizomes and associated buds persist through co-occurring disturbances.

}, keywords = {LTER-KNZ, Climate change, Ecological stability, Herbivory, tallgrass prairie, water stress}, doi = {10.1007/s00442-015-3249-y}, url = {https://link.springer.com/article/10.1007\%2Fs00442-015-3249-y}, author = {VanderWeide, B.L. and D.C. Hartnett} } @article {KNZ001549, title = {Coping with herbivory at the juvenile stage: Responses to defoliation and browsing in the African savanna tree Colophospermum mopane}, journal = {Journal of Tropical Ecology}, volume = {28}, year = {2012}, pages = {161 -169}, abstract = {

Responses of plants to herbivory are dependent on the type of damage and the ontogenetic stage of the plant. We compared the effects of stem pruning and defoliation on seedlings of Colophospermum mopane, an ecologically important tree species widely distributed in southern Africa. The growth of 160 greenhouse-grown juveniles were measured for 6-mo after germination and then 6-mo after treatments including 50\% defoliation, 100\% defoliation, 50\% stem pruning and controls. Pruning resulted in 30\% reductions in total leaf area, height and biomass. Partial defoliation resulted in 30\% reductions in total leaf area and plant biomass. However, complete defoliation resulted in a 30\% increase in biomass production, a doubling in leaf and lateral branch number, a 45\% reduction in leaf size, and no change in total leaf area. Thus, completely defoliated seedlings showed greater performance than those that were only partially defoliated, indicating that C. mopane has become adapted to the chronic and severe defoliation inflicted by Imbrasia belina caterpillars. Comparison of our results with other studies indicates that C. mopane seedlings are less herbivory-tolerant than adults and that pruning has more negative effects than defoliation. Thus, seedling browsers may constrain recruitment in C. mopane, influencing its population dynamics and abundance.

}, keywords = {LTER-KNZ, Botswana, browsing, defoliation, Herbivory, Plant{\textendash}herbivore interactions, savanna, seedlings, tree recruitment}, doi = {http://dx.doi.org/10.1017/S0266467412000028 }, url = {https://www.cambridge.org/core/journals/journal-of-tropical-ecology/article/coping-with-herbivory-at-the-juvenile-stage-responses-to-defoliation-and-stem-browsing-in-the-african-savanna-tree-colophospermum-mopane/5B519E0F1B9BD889D4905FD311257D9A}, author = {D.C. Hartnett and Ott, J.P. and Sebes, K. and Ditlhogo, M.} } @article {KNZ001363, title = {Differential responses to defoliation frequency in Little Bluestem (Schizachyrium scoparium) in tallgrass prairie: Implications for herbivory tolerance and avoidance}, journal = {Plant Ecology}, volume = {212}, year = {2011}, pages = {1275 -1285}, abstract = {

Plant responses to herbivory are complex. In grasses, relative growth rate (RGR), seed, and vegetative reproduction, resource allocation, and architecture vary differentially and often nonlinearly with grazing intensity. High grazing tolerance may be achieved through compensatory photosynthesis and leaf growth, or through demographic mechanisms such as activation of a belowground dormant bud bank. This study assessed the relationship between grazing frequency and responses of Schizachyrium scoparium (little bluestem) in a tallgrass prairie, and examined the roles of tiller growth, reproduction, and bud (meristem) populations in its persistence under grazing. Genets were subjected to varying simulated grazing frequencies for a period of 2 years. Strong differential responses were observed among plant traits. RGR, biomass, and flowering showed strong nonlinear reductions in response to increasing clipping frequency, with no evidence of threshold effects. However, meristem density was unaffected, and plants maintained a large bud bank across all clipping treatments. Tiller natality decreased initially, but increased with \>4 clippings, suggesting that declines in tiller RGR are partially offset by increasing tiller natality, and that variation in genet size is driven more by demography than by variation in individual tiller growth. Increased grazing frequency also resulted in differential activation of buds at different positions (emerging within vs. outside the subtending leaf sheath), explaining the shift to a more prostrate growth form observed in many caespitose grasses under persistent grazing. Thus, although this grass species lacks the capacity for compensatory foliage re-growth, the maintenance of a large dormant bud bank and the differential activation of buds in different positions contribute to its grazing tolerance and avoidance, respectively, and its long-term persistence in grazed grasslands.

}, keywords = {LTER-KNZ, bud banks, Compensation, demography, Grasses, Grazing, Herbivory}, doi = {10.1007/s11258-011-9904-4}, url = {https://link.springer.com/article/10.1007\%2Fs11258-011-9904-4}, author = {N{\textquoteright}Guessan, M. and D.C. Hartnett} } @article {KNZ001105, title = {Effects of prairie vole runways on tallgrass prairie}, journal = {Transactions of the Kansas Academy of Science}, volume = {110}, year = {2007}, pages = {100 -106}, abstract = {Disturbances by large mammals influence plant populations and ecosystem processes. In contrast, impacts on ecosystem processes at local scales by small herbivorous rodents are relatively unknown. To examine effects of the runways of prairie voles (Microtus ochrogaster) on soil nitrogen, we collected soil cores from under runways, along the runway edges and at 0.25 and 2 m away from runways. Plant samples (both current and previous year{\textquoteright}s growth) were clipped from microsites at edges of runways and at 0.25 and 2 m away from runways. Concentrations of soil nitrate were highest along runway edges and lowest 2 m away, whereas those of ammonium were highest 0.25 m away from runways and lowest under runways and along runway edges. Biomass of plants from previous growth (litter) was higher along edges of runways than at 0.25 and 2 m from runway edges. In contrast to differences in soil nitrate and ammonium concentrations and in litter biomass among microsites, carbon: nitrogen (C:N) ratios of big bluestem and live plant biomass were similar among the three microsites. Our data suggest that prairie voles do affect nutrient dynamics and plant litter at a local scale in tallgrass prairie.}, keywords = {LTER-KNZ, C:N ratios, Herbivory, Microtus ochrogaster, nitrogen dynamics, plant biomass, plant-animal interaction, prairie vole, runways}, doi = {10.1660/0022-8443(2007)110[100:EOPVRO]2.0.CO;2}, author = {Ross, B.E. and Reed, A.W. and Rehmeier, R.L. and Kaufman, G.A. and D.W. Kaufman} } @article {KNZ001002, title = {Branching responses in Silphium integrifolium (Asteraceae) following mechanical or gall damage to apical meristems and neighbor removal}, journal = {American Journal of Botany}, volume = {92}, year = {2005}, pages = {954 -959}, abstract = {Branching in plants increases plant access to light and provides pathways for regrowth following damage or loss of the apical meristem. We conducted two experiments in an eastern Kansas tallgrass prairie to determine how apical meristem loss (by clipping), apical meristem damage (by insect galling), and increased light availability affected growth, reproduction, and branching in Silphium integrifolium (Asteraceae). The first experiment compared clipping with galling. Clipping increased axillary shoot numbers, while galling increased axillary shoot lengths, reflecting different allocation responses among damage types and inhibition of branching by galls. However, total capitulum production was less in all gall/clip treatments than in intact shoots. The second experiment compared clipping with mowing the surrounding vegetation to increase light availability. Mowing increased total leaf, total capitulum, and axillary shoot length and axillary capitulum production in clipped and unclipped plants and in large vs. small shoots. The presence of the neighboring canopy, not of an intact apical meristem, was therefore the stronger limitation on leaf and capitulum production. These experiments suggest that damage and light competition affected both branching frequency and the partitioning of resources among shoots, branches, and leaves. Because Silphium{\textquoteright}s growth form is widespread, similar responses may occur in other grassland forbs.}, keywords = {LTER-KNZ, Antistrophus silphii, apical dominance, Asteraceae, branching competition, galls, Herbivory, Konza Prairie}, doi = {10.3732/ajb.92.6.954}, author = {Fay, P.A. and Throop, H.L.} } @article {KNZ003, title = {A comparison of the trophic ecology of crayfish (Orconectes nais (Faxon) and Orconectes neglectus (Faxon)) and central stonerollers (Compostoma anomalum (Rafinesque)): omnivory in a tallgrass prairie stream}, journal = {Hydrobiologia}, volume = {462}, year = {2001}, pages = {131 -144}, abstract = {Omnivorous fish, such as the central stoneroller minnow (Campostoma anomalum(Rafinesque)), and crayfish often play important roles in the trophic dynamics of streams. The trophic role of these two omnivores has not been compared within a system even though they both consume algae, detritus and invertebrates and often co-occur in streams in the Midwestern United States. Natural abundance of 15N and 13C isotopes and a whole stream 15N-labeled ammonium chloride release were used to compare the trophic ecology of the central stoneroller minnow (Campostoma anomalum (Rafinesque)) and two species of crayfish (Orconectes neglectus (Faxon) and Orconectes nais (Faxon)) in a tallgrass prairie stream. The δ15N and δ13C values of Orconectes spp. were more similar to coarse benthic organic matter (CBOM) and filamentous green algae than to invertebrates, fine benthic organic matter (FBOM), and periphyton. Values for δ15N and δ13C in C. anomalum were more similar to grazer and collector invertebrates and filamentous green algae than to FBOM and periphyton. Results from a 15N tracer release also indicated a portion of algae and/or invertebrates were a component of nitrogen assimilated in Orconectes spp. and C. anomalum diets. Gut contents of C. anomalum were also analyzed. In contrast to stable isotope data, amorphous detritus was a significant component of C. anomalum guts, followed by diatoms and filamentous green algae. A significant percentage of invertebrate material was found in C. anomalum guts sampled in the spring. Experiments were conducted in artificial streams to determine if Orconectes spp. and C. anomalum could reduce epilithic algal biomass in small streams. Algal biomass on clay tile substrata was decreased relative to controls in artificial stream channels containing O. neglectus (3.4 fold, p=0.0002), C. anomalum (2.1 fold, p=0.0012), and both species combined (3.0 fold, p=0.0003). Results indicate that Orconectes spp. are functioning more as algal and detrital processors than as predators in Kings Creek. Isotope and gut content data show that C. anomalum includes invertebrates as well as algae and detritus in its diet. Both species have the potential to affect algal biomass and are important omnivores in the stream food web.}, keywords = {LTER-KNZ, food webs, gut analysis, Herbivory, omnivory, Stable isotopes}, doi = {10.1023/A:1013182100150}, author = {Evans-White, M.A. and W. K. Dodds and Gray, L. and Fritz, K.M.} }