02569nas a2200265 4500008004100000245012600041210006900167300001100236490000600247520170500253653002301958653003601981653002002017653002102037653002602058653002302084653002402107653001702131653002202148100001702170700001602187700001502203700001602218856006902234 2015 eng d00aThe effects of genotype richness and genomic dissimilarity of Andropogon gerardii on invasion resistance and productivity0 aeffects of genotype richness and genomic dissimilarity of Androp a61 -710 v83 a

Background: The genetic diversity within populations has been shown to affect ecosystem functions, including productivity and invasion resistance. To date most experiments have focused on manipulation of genotypic richness and have ignored other measures of genetic diversity. Aims: In the present study we aimed to establish whether manipulated genotypic richness and genomic dissimilarity of Andropogon gerardii affect productivity and invasion resistance. Methods: We created experimental mesocosms with three levels of genotypic richness: one-, three-, and nine-genotypes. In the three-genotype treatment, we manipulated a range of genomic dissimilarity values (genetic relatedness among individuals). At the end of one growing season we measured above-ground, below-ground and total biomass of the mesocosms, and invasion resistance to Andropogon bladhii. Results: Overall, we found no significant effect of genotypic richness on any measure of ecosystem function, although there tended to be more root biomass (due to complementarity) and invasive seedling biomass with higher levels of genotypic richness. Within the three-genotype treatment we found a significant positive relationship between genomic dissimilarity and above-ground biomass, which was caused by a selection effect. We also found a positive relationship between genomic dissimilarity and biomass of A. bladhii. Conclusions: Using these two measures of genetic diversity we detected differences in the strength and mechanism of positive diversity effects within the same experiment, demonstrating the value of manipulating multiple measures of diversity when performing biodiversity–ecosystem function experiments.

10aAndropogon bladhii10abiodiversity ecosystem function10acomplementarity10adominant species10agenomic dissimilarity10agenotypic richness10ainvasion resistance10aproductivity10atallgrass prairie1 aAvolio, M.L.1 aChang, C.C.1 aWeis, J.J.1 aSmith, M.D. uhttps://www.tandfonline.com/doi/abs/10.1080/17550874.2013.86699001969nas a2200193 4500008004100000245008300041210006900124300001300193490000800206520136600214653001901580653002101599653002001620653001901640653001701659100001701676700001601693856006601709 2014 eng d00aContrasting sensitivities of two dominant C4 grasses to heat waves and drought0 aContrasting sensitivities of two dominant C4 grasses to heat wav a721 -7310 v2153 a

Heat waves and droughts are predicted to increase in frequency and intensity with climate change. However, we lack a mechanistic understanding of the independent and interactive effects of severe heat and water stress for most ecosystems. In a mesic tallgrass prairie ecosystem, we used a factorial experimental approach to assess ecophysiological and productivity responses of two dominant C4 grasses, Andropogon gerardii and Sorghastrum nutans, to a season-long drought and a mid-summer heat wave at four intensities. We hypothesized that drought would have greater impacts than heat waves, that combined effects would be greater than either factor alone, and that the dominant grasses would differ in their responses to heat and water heat stress. We detected significant reductions in photosynthesis, leaf water potential, and productivity with drought but few direct responses to the heat waves. Surprisingly, there was no additive effect of heat and water stress on any plant response. However, S. nutans was more sensitive than A. gerardii to drought. In this grassland, water stress will likely dominate photosynthetic and productivity responses caused by discrete drought and heat wave events, rather than direct or additive effects of heat stress, with differential sensitivity in these grasses altering future ecosystem structure and function.

10aClimate change10aClimate extremes10aMesic grassland10aphotosynthesis10aproductivity1 aHoover, D.L.1 aSmith, M.D. uhttps://link.springer.com/article/10.1007%2Fs11258-014-0345-802898nas a2200205 4500008004100000245011700041210006900158300001300227490000600240520226200246653001402508653001402522653001702536653001102553653001702564100001902581700001602600700002002616856005602636 2014 eng d00aGeographic variation in growth and phenology of two dominant Central US grasses: Consequences for climate change0 aGeographic variation in growth and phenology of two dominant Cen a211 -2210 v73 a

Aims The rate of climate change may exceed many plant species’ migration rates, particularly for long-lived perennial species that dominate most ecosystems. If bioclimatic envelopes shift more rapidly than dominant species can migrate, individuals located peripheral to biomes or in adjacent biomes may become a significant source of traits for future dominant populations (DPs). Thus, traits of individuals from peripheral populations (PPs) may affect future ecosystem functioning more than those of today’s DPs. Methods We assessed key traits of individuals collected from populations that currently dominate two central US grasslands, the shortgrass steppe (Bouteloua gracilis) and the tallgrass prairie (Andropogon gerardii). We compared these to individuals from PPs in a reciprocal-transplant common garden experiment with gardens at the Shortgrass Steppe Long Term Ecological Research site in Colorado and the Konza Prairie Biological Station Long Term Ecological Research site in Kansas. DPs and PPs were subjected to high and reduced water availability in common gardens located in each biome. Traits measured included the following: individual plant biomass, reproductive allocation, specific leaf area (SLA) and plant–water relations. We focused on the climate-change relevant comparisons of traits from PPs versus DPs expressed under the climate of DPs. Important Findings PPs of B. gracilis differed from DPs primarily in phenological traits. Under a semiarid shortgrass steppe climate, PPs initiated flowering later in the season, produced fewer reproductive tillers and were more sensitive to water stress. Biomass differences between populations were minimal. For A. gerardii, biomass in PPs was 50% lower than in DPs under the mesic tallgrass prairie climate and reproductive tillers were considerably smaller, despite higher SLA in PPs. Biomass of PPs was less sensitive to water stress, however. From these results, we conclude that key traits of PPs differed from DPs in both grassland types, but potential effects on reproductive phenology were greater for the bioclimatic shift in which a mesic biome becomes arid, whereas aboveground productivity may be affected more when a semiarid biome becomes more mesic.

10agrassland10aphenology10aproductivity10atraits10awater stress1 aGiuliani, A.L.1 aKelly, E.F.1 aKnapp, Alan, K. uhttps://academic.oup.com/jpe/article/7/3/211/90574602994nas a2200229 4500008004100000245009000041210006900131300001300200490000600213520223900219653002402458653002602482653002402508653004302532653002202575653004002597653001702637653002202654100001602676700001602692856005602708 2013 eng d00aGenotypic diversity of a dominant C4 grass across a long-term fire frequency gradient0 aGenotypic diversity of a dominant C4 grass across a longterm fir a448 -4580 v63 a

Aims and Methods Diversity-disturbance research has focused on community diversity, but disturbance frequency could impact diversity within species as well, with important consequences for community diversity and ecosystem function. We examined patterns of genetic diversity of a dominant grass species, Andropogon gerardii, in native North American tallgrass prairie sites located in eastern Kansas that have been subjected to a gradient of fire frequency treatments (burned every 1, 2, 4 or 20 years) since the 1970s. In addition, we were able to assess the relationships between genetic diversity of A. gerardii, species diversity and productivity across this range of fire frequencies. Important Findings We found no significant relationships between genetic diversity of A. gerardii at the local scale (1 m2 plot level) and disturbance frequency (burned 2 to 32 times over a 38-year period). However, at the site level (i.e. across all plots sampled within a site, ~100 m2) there were differences in genotype richness and composition, as well as genomic dissimilarity among individuals of A. gerardii. Genotype richness was greatest for the site burned at an intermediate (4-year) frequency and lowest for the infrequently (20-year) burned site. In addition, genotypes found in the frequently burned sites were more similar from each other than expected by random chance than those found in the infrequently burned sites. Genotype composition of A. gerardii was not significantly different between the frequently burned sites (annual vs. 2 year) but did differ between frequently burned and infrequently burned sites (1 and 2 year vs. 4 and 20 year, etc.). Together, these results suggest site-level ecological sorting of genotypes in intact prairie across a broad gradient of disturbance frequencies, likely driven by alterations in environmental conditions. Frequent fire promotes the abundance of dominant grass species, reduces plant community diversity and impacts ecosystem processes such as productivity. Our study suggests that genetic diversity within dominant grass species also may be affected by disturbance frequency, which could have important implications for how species are able to respond to disturbance.

10aAndropogon gerardii10adisturbance frequency10agenetic relatedness10agenetic-species diversity relationship10agenotype richness10aintermediate disturbance hypothesis10aproductivity10atallgrass prairie1 aChang, C.C.1 aSmith, M.D. uhttps://academic.oup.com/jpe/article/6/6/448/98097703012nas a2200265 4500008004100000245011300041210006900154300000900223490000600232520219900238653001802437653002402455653001402479653002202493653002102515653002802536653001702564653001502581653001602596653002302612653001402635100001702649700002002666856006002686 2013 eng d00aSeed source has variable effects on species, communities, and ecosystem properties in grassland restorations0 aSeed source has variable effects on species communities and ecos a93 -0 v43 aResearch to date regarding the relative advantages of local versus non-local sources of plantmaterial for restoration has produced equivocal results. This research has typically focused on theperformance of individual species at individual locations and without addressing higher order communityand ecosystem properties. We investigated the effects of seed source (local, non-local, and mixed-sourcetreatments) on species, community, and ecosystem properties under a range of environmental conditionsusing reciprocal common gardens at locations in three states (Nebraska, Kansas, and Oklahoma). In orderto mimic the restoration of grassland vegetation under realistic conditions where multiple species interactwith one another during establishment, we seeded twelve species together between December, 2009 andJanuary, 2010, and assessed responses in 2010, 2011, and 2012. Both common garden location and seedsource affected the establishment of individual species (measured as species-specific biomass), butresponses were not consistent among species. No seed source had a consistent advantage across all sites oracross all species. In a few cases, the local source was most productive for a particular species at onelocation, but no species showed a consistent local advantage across locations or years. Rather, in two out ofthree species that exhibited a local advantage at one location, the same source was also the most productiveat a non-local site. Community structure and species richness differed among locations in all years, butsource did not significantly affect seeded species richness, and source only affected community structure in2011. Despite source effects on individual species and community structure, seed source had no significanteffects on the combined productivity of seeded species. These results do not support the targeted use oflocal sources when the establishment of sown species and primary productivity are restoration objectives.Using mixed-source species mixtures may increase chances of restoration success, given the idiosyncrasy ofindividual species’ responses among locations and potential site-specific environmental changes likely tooccur in the future.10acommon garden10acommunity structure10adispersal10agenetic diversity10alocal adaptation10amanaged relocationplant10aproductivity10aprovenance10arestoration10aseed transfer zone10atallgrass1 aCarter, D.L.1 aBlair, John, M. uhttp://www.esajournals.org/doi/pdf/10.1890/ES13-00090.101961nas a2200265 4500008004100000245010500041210006900146300001500215490000800230520116100238653001801399653001601417653001401433653002201447653001701469100001401486700001601500700001801516700001601534700002401550700001901574700001901593700001701612856006601629 2012 eng d00aIncorporating clonal growth form clarifies the role of plant height in response to nitrogen addition0 aIncorporating clonal growth form clarifies the role of plant hei a1053 -10620 v1693 a

Nutrient addition to grasslands consistently causes species richness declines and productivity increases. Competition, particularly for light, is often assumed to produce this result. Using a long-term dataset from North American herbaceous plant communities, we tested whether height and clonal growth form together predict responses to fertilization because neither trait alone predicted species loss in a previous analysis. Species with a tall-runner growth form commonly increased in relative abundance in response to added nitrogen, while short species and those with a tall-clumped clonal growth form often decreased. The ability to increase in size via vegetative spread across space, while simultaneously occupying the canopy, conferred competitive advantage, although typically only the abundance of a single species within each height-clonal growth form significantly responded to fertilization in each experiment. Classifying species on the basis of two traits (height and clonal growth form) increases our ability to predict species responses to fertilization compared to either trait alone in predominantly herbaceous plant communities.

10aClonal growth10aCompetition10agrassland10aNitrogen addition10aproductivity1 aGough, L.1 aGross, K.L.1 aCleland, E.E.1 aClark, C.M.1 aCollins, Scott., L.1 aFargione, J.E.1 aPennings, S.C.1 aSuding, K.N. uhttps://link.springer.com/article/10.1007%2Fs00442-012-2264-502567nas a2200229 4500008004100000245010800041210006900149300001300218490000800231520185700239653002502096653001502121653001402136653001502150653001902165653001702184653002002201100002102221700001702242700001902259856005902278 2008 eng d00aEffects of experimental cowbird removals on brood parasitism and nest predation in a grassland songbird0 aEffects of experimental cowbird removals on brood parasitism and a820 -8300 v1253 a

Brood parasitism and predation are two factors that limit seasonal fecundity in grassland songbirds. We removed Brown-headed Cowbirds (Molothrus ater) in a switchback experiment to examine the effects of brood parasitism and nest predation on the productivity of Dickcissels (Spiza americana). Nesting Dickcissels were monitored at four study plots in northeast Kansas in a two-year study. Brown-headed Cowbirds were captured with drop-in traps at two removal plots, two unmanipulated plots were reference plots, and treatments were reversed between years. To evaluate the effect of Brown-headed Cowbird removals, we compared the percentage of nests parasitized, rates of multiple parasitism, clutch size, daily nest survival rates, and overall productivity per nest between removal and reference plots. Removals of Brown-headed Cowbirds successfully reduced the probability of parasitism and rates of multiple parasitism, but only in one of two years. Brown-headed Cowbirds did not appear to contribute to nest losses, given that few nests were abandoned because of cowbird activity and that the probabilities of nest parasitism and nest survival declined simultaneously over the breeding season. Overall, nest productivity showed no difference between treatments in either year, despite reduced rates of parasitism at removal plots in 2004. High rates of nest predation minimized the potential benefits of Brown-headed Cowbird removals for increasing productivity of Dickcissels. Our results demonstrate that removals can reduce parasitism levels but that the success of removal programs may vary annually, particularly in regions where Brown-headed Cowbirds and nest predators are abundant. Management actions that minimize parasitism and predation by modifying habitat structure may provide better alternatives to programs based on removals.

10abrown-headed cowbird10aDickcissel10afecundity10amanagement10aMolothrus ater10aproductivity10aSpiza americana1 aSandercock, B.K.1 aHewett, E.L.1 aKosciuch, K.L. uhttps://academic.oup.com/auk/article/125/4/820/514820601254nas a2200157 4500008004100000245006600041210006600107300001300173490000800186520075000194653001000944653001200954653001700966100001900983856009401002 1985 eng d00aMaximization of primary and secondary productivity by grazers0 aMaximization of primary and secondary productivity by grazers a559 -5640 v1263 a

Not only have consumers coevolved with their food resources, but they have coevolved with them as these resources have been modified by other herbivores and detritivores. Current theory states that most plants respond to herbivory by producing chemical that adversely affect the growth or survivorship of the herbivores. Certain consumers, however, may exhibit positive growth responses when these changes in plant chemistry occur. Increased growth is predicted whenever herbivory increases the quality of the food resource via plant stress or when it removes chemicals having a negative effect on the palatability or assimilation of the resource. I suggest that these positive responses are more widespread than is currently acknowledged

10agraze10aprimary10aproductivity1 aSeastedt, T.R. uhttp://lter.konza.ksu.edu/content/maximization-primary-and-secondary-productivity-grazers