02581nas a2200217 4500008004100000245007000041210006900111300001100180490000700191520192800198653002802126653001702154653002302171653000902194653001802203653001802221653001802239100001702257700002302274856006602297 2014 eng d00aCessation of burning dries soils long-term in a tallgrass prairie0 aCessation of burning dries soils longterm in a tallgrass prairie a54 -650 v173 a
Soil moisture is a critical variable in grassland function, yet how fire regimes influence ecohydrology is poorly understood. By altering productivity, species composition, and litter accumulation, fire can indirectly increase or decrease soil water depletion on a range of time scales and depths in the soil profile. To better understand how fire influences soil moisture in grasslands, we analyzed 28 years of soil moisture data from two watersheds in a central North American grassland which differ in their long-term fire frequency. Across 28 years, cessation of prescribed burning initially led to wetter soils, likely as litter accumulated and both transpiration and evaporation were suppressed. Long-term, cessation of burning led to soils drying more, especially at depths greater than 75 cm. The long-term drying of deep soils is consistent with the increase in woody species in the infrequently burned grassland as woody species likely have a greater reliance on soil water from deeper soil layers compared to co-occurring herbaceous species. Despite the ecohydrological changes associated with the cessation of prescribed burning, watersheds with different burn regimes responded similarly to short-term variation in climate variation. In both watersheds, low precipitation and high temperatures led to drier soils with greater responses in soil moisture to climate variation later in the season than earlier. There is no current evidence that the cessation of burning in this ecosystem will qualitatively alter how evapotranspiration responds to climate variation, but the use of deeper soil water by woody plants has the potential for greater transpiration during dry times. In all, modeling the depth-specific responses of soil moisture and associated ecosystem processes to changes in burn regimes will likely require including responses of plant community composition over short and long time scales.
10acritical climate period10aecohydrology10aEvapotranspiration10afire10aKonza Prairie10asoil moisture10awoody species1 aCraine, J.M.1 aNippert, Jesse, B. uhttps://link.springer.com/article/10.1007%2Fs10021-013-9706-802260nas a2200121 4500008004100000245008000041210006900121490001500190520182200205100001602027700001702043856007802060 2014 eng d00aEcological consequences of shifting the timing of burning tallgrass prairie0 aEcological consequences of shifting the timing of burning tallgr0 v9: e1034233 aIn the Kansas Flint Hills, grassland burning is conducted during a relatively narrow window because management recommendations for the past 40 years have been to burn only in late spring. Widespread prescribed burning within this restricted time frame frequently creates smoke management issues downwind. A potential remedy for the concentrated smoke production in late spring is to expand burning to times earlier in the year. Yet, previous research suggested that burning in winter or early spring reduces plant productivity and cattle weight gain while increasing the proportion of undesirable plant species. In order to better understand the ecological consequences of burning at different times of the year, plant production and species abundance were measured for 20 years on ungrazed watersheds burned annually in autumn, winter, or spring. We found that there were no significant differences in total grass production among the burns on either upland or lowland topographic positions, although spring burned watersheds had higher grass culm production and lower forb biomass than autumn and winter burned watersheds. Burning in autumn or winter broadened the window of grass productivity response to precipitation, which reduces susceptibility to mid-season drought. Burning in autumn or winter also increased the phenological range of species by promoting cool-season graminoids without a concomitant decrease in warm-season grasses, potentially widening the seasonal window of high-quality forage. Incorporating autumn and winter burns into the overall portfolio of tallgrass prairie management should increase the flexibility in managing grasslands, promote biodiversity, and minimize air quality issues caused by en masse late-spring burning with little negative consequences for cattle production.
1 aTowne, E.G.1 aCraine, J.M. uhttps://journals.plos.org/plosone/article?id=10.1371/journal.pone.010342301891nas a2200157 4500008004100000245007400041210006900115300001500184490000700199520137200206100002101578700001701599700002301616700002001639856007401659 2014 eng d00aLack of eutrophication in a tallgrass prairie ecosystem over 27 years0 aLack of eutrophication in a tallgrass prairie ecosystem over 27 a1225 -12350 v953 aMany North American grasslands are receiving atmospheric nitrogen (N) deposition at rates above what are considered critical eutrophication thresholds. Yet, potential changes in grassland function due to anthropogenic N deposition are poorly resolved, especially considering that other dynamic factors such as land use and precipitation can also affect N availability. To better understand whether elevated N deposition has altered ecosystem structure or function in North American grasslands, we analyzed a 27-year record of ecophysiological, community, and ecosystem metrics for an annually burned Kansas tallgrass prairie. Over this time, despite increasing rates of N deposition that are within the range of critical loads for grasslands, there was no evidence of eutrophication. Plant N concentrations did not increase, soil moisture did not decline, forb diversity did not decline, and the relative abundance of dominant grasses did not shift toward more eutrophic species. Neither aboveground primary productivity nor N availability to plants increased. The fates of deposited N in grasslands are still uncertain, and could include management losses through burning and grazing. However, evidence from this grassland indicates that eutrophication of North American grassland ecosystems is not an inevitable consequence of current levels of N deposition.
1 aMcLauchlan, K.K.1 aCraine, J.M.1 aNippert, Jesse, B.1 aOcheltree, T.W. uhttps://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/13-1068.102135nas a2200229 4500008004100000245008200041210006900123300001100192490000600203520145700209653002701666653001201693653002201705100001701727700002001744700002301764700001601787700001701803700001701820700001901837856004901856 2013 eng d00aGlobal diversity of drought tolerance and grassland climate-change resilience0 aGlobal diversity of drought tolerance and grassland climatechang a63 -670 v33 aDrought reduces plant productivity, induces widespread plant mortality and limits the geographic distribution of plant species1, 2, 3, 4, 5, 6, 7. As climates warm and precipitation patterns shift in the future8, 9, understanding the distribution of the diversity of plant drought tolerance is central to predicting future ecosystem function and resilience to climate change10, 11, 12. These questions are especially pressing for the world’s 11,000 grass species13, which dominate a large fraction of the terrestrial biosphere14, yet are poorly characterized with respect to responses to drought. Here, we show that physiological drought tolerance, which varied tenfold among 426 grass species, is well distributed both climatically and phylogenetically, suggesting most native grasslands are likely to contain a high diversity of drought tolerance. Consequently, local species may help maintain ecosystem functioning in response to changing drought regimes without requiring long-distance migrations of grass species. Furthermore, physiologically drought-tolerant species had higher rates of water and carbon dioxide exchange than intolerant species, indicating that severe droughts may generate legacies for ecosystem functioning. In all, our findings suggest that diverse grasslands throughout the globe have the potential to be resilient to drought in the face of climate change through the local expansion of drought-tolerant species.
10aClimate-change ecology10aDrought10aGrassland ecology1 aCraine, J.M.1 aOcheltree, T.W.1 aNippert, Jesse, B.1 aTowne, E.G.1 aSkibbe, A.M.1 aKembel, S.W.1 aFargione, J.E. uhttps://www.nature.com/articles/nclimate163401746nas a2200193 4500008004100000245007300041210006900114300001500183490000800198520114800206653002801354653001501382653001801397653001801415653002501433653001101458100001701469856006601486 2013 eng d00aThe importance of timing of precipitation for grassland productivity0 aimportance of timing of precipitation for grassland productivity a1085 -10890 v2133 aFuture climate change is likely to involve changes in the amount and intensity of precipitation, but also its timing during the year. To better understand how the timing of precipitation impacts plant productivity, a 27-year dataset on grass productivity for a mesic North American grassland was analyzed. Along with other climate parameters, the ability of the average date precipitation fell during different climate periods to explain grass productivity was tested. Across the 27 years, grass productivity was greater in years with more precipitation between April 15 and August 2. After accounting for differences in the total amount of precipitation during this time period, in years when precipitation between May 9 and August 27 fell later, measured grass productivity was less. Variation among years in precipitation timing was of similar importance as temperatures during critical climate periods and about 40 % of the importance of the total amount of precipitation. In all, although the mechanisms generating these responses are uncertain, precipitation timing within a growing season has substantial effects on productivity.
10acritical climate period10aGrasslands10aKonza Prairie10aPrecipitation10aPrimary productivity10aTiming1 aCraine, J.M. uhttps://link.springer.com/article/10.1007%2Fs11258-013-0236-402261nas a2200217 4500008004100000245007600041210006900117300001200186490000600198520162200204653002301826653001001849653001101859653001901870653001201889653001501901653001601916653001601932100001701948856007801965 2013 eng d00aLong-term climate sensitivity of grazer performance: a cross-site study0 aLongterm climate sensitivity of grazer performance a crosssite s a67065 -0 v83 aClimate change will affect grasslands in a number of ways, but the consequences of a warmer, drier world for grazers is uncertain. Predicting future grazer performance is complex since climate change affects both the quantity and quality of forage through a combination of processes that occur over a range of time scales. To better predict the consequences of climate change for grazer performance, a dataset was compiled of over a quarter million bison weights distributed across 22 US herds that span a large range of climates. Patterns of bison body mass among sites, age classes, and sexes were analyzed with respect to differences in geographic patterns of climate and interannual variation in climate. While short-term effects of climate variability are likely to depend on the magnitude and timing of precipitation during the year, grazers will be negatively affected by sustained hotter, drier conditions most likely associated with reductions in forage quality. Short-term, little effect of high temperatures on bison performance is observed, which suggests that the long-term effects of higher temperatures are likely to accrue over time as nitrogen availability in grasslands is reduced and forage quality declines. If relationships observed for bison are general for cattle, the economic consequences of higher temperatures due to decreased weight gain in US cattle could be on the order of US$1B per 1°C increase in temperature. Long-term monitoring of forage quality as well as native and domesticated grazer performance is recommended to better understand climate change effects on grazers.
10aAnimal performance10abison10aCattle10aClimate change10aGrasses10aGrasslands10aMeteorology10aWeight gain1 aCraine, J.M. uhttps://journals.plos.org/plosone/article?id=10.1371/journal.pone.006706501507nas a2200157 4500008004100000245007100041210006900112300001300181490000800194520099700202100001701199700001601216700001701232700002301249856007701272 2013 eng d00aPrecipitation timing and grazer performance in a tallgrass prairie0 aPrecipitation timing and grazer performance in a tallgrass prair a191 -1980 v1223 aChanges in precipitation amount and variability have the potential to alter the structure and function of grasslands, but we know little about how changes in the timing of precipitation might affect grasslands. Here, we analyze long-term records from a tallgrass prairie to show that shifts in the timing of precipitation during the growing season have little effect on primary productivity or grass reproduction, but can greatly affect grazer performance. While greater late-season precipitation increases the weight gain of adult and young bison, greater mid-season precipitation decreases their weight gain. In addition, calving rates are lower after years with greater mid-season precipitation and higher after years with greater late-season precipitation. As well-timed drought can actually increase grazer weight gain and reproduction, it will be necessary to generate predictions of within-season distribution of precipitation to successfully forecast future grazer performance.
1 aCraine, J.M.1 aTowne, E.G.1 aTolleson, D.1 aNippert, Jesse, B. uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/j.1600-0706.2012.20400.x02086nas a2200229 4500008004100000245010700041210006900148300001300217490000800230520136700238653002301605653001601628653001501644653001301659653001801672653002401690100001701714700001601731700002001747700002301767856006601790 2012 eng d00aCommunity traitscape of foliar nitrogen isotopes reveals N availabiity patterns in a tallgrass prairie0 aCommunity traitscape of foliar nitrogen isotopes reveals N avail a395 -4030 v3563 aBackground and aims Nutrients are important determinants of community assembly, yet the roles they play in structuring plant communities are still poorly understood. One inferential approach to understanding how environmental factors structure plant communities is examining the distribution of key functional traits among species of a community—a community traitscape. Methods To better understand how nitrogen (N) and water availability structure grasslands, we measured N concentrations and isotope ratios for 366 herbaceous species in a mesic N-limited temperate grassland, Konza Prairie. We also compared foliar N concentrations and N isotopes between Konza species and a global dataset. Results Species that had either high foliar N concentrations or high δ15NL were not necessarily more or less abundant on the landscape nor more or less likely to be found in uplands, grazed areas, or burned areas. Apparently there are unique hot spots of high N availability at Konza and the typical non-Fabaceae Konza species occupies sites with greater N availability than found globally. Conclusions Although nascent, the Konza traitscapes suggest that plant diversity in nutrient-limited communities might be strongly dependent on high-nutrient availability sites that enable high-fertility species to persist in a matrix of low nutrient availability.
10aCommunity assembly10adisturbance10aGrasslands10aIsotopes10aKonza Prairie10aResource limitation1 aCraine, J.M.1 aTowne, E.G.1 aOcheltree, T.W.1 aNippert, Jesse, B. uhttps://link.springer.com/article/10.1007%2Fs11104-012-1141-701807nas a2200157 4500008004100000245006900041210006900110300001300179490000800192520129700200100001701497700002001514700001601534700001701550856008201567 2012 eng d00aFlowering phenology as a functional trait in a tallgrass prairie0 aFlowering phenology as a functional trait in a tallgrass prairie a673 -6820 v1933 a•The timing of flowering is a critical component of the ecology of plants and has the potential to structure plant communities. Yet, we know little about how the timing of flowering relates to other functional traits, species abundance, and average environmental conditions. •Here, we assessed first flowering dates (FFDs) in a North American tallgrass prairie (Konza Prairie) for 431 herbaceous species and compared them with a series of other functional traits, environmental metrics, and species abundance across ecological contrasts. •The pattern of FFDs among the species of the Konza grassland was shaped by local climate, can be linked to resource use by species, and patterns of species abundance across the landscape. Peak FFD for the community occurred when soils were typically both warm and wet, while relatively few species began flowering when soils tended to be the driest. Compared with late-flowering species, species that flowered early had lower leaf tissue density and were more abundant on uplands than lowlands. •Flowering phenology can contribute to the structuring of grassland communities, but was largely independent of most functional traits. Therefore, selection for flowering phenology may be independent of general resource strategies.
1 aCraine, J.M.1 aWolkovich, E.M.1 aTowne, E.G.1 aKembel, S.W. uhttps://nph.onlinelibrary.wiley.com/doi/full/10.1111/j.1469-8137.2011.03953.x02554nas a2200145 4500008004100000245006300041210006300104300001500167490000700182520209800189100001402287700001702301700001602318856007402334 2012 eng d00aMaternal allocation and offspring characteristics in Bison0 aMaternal allocation and offspring characteristics in Bison a1628 -16390 v223 aParental allocation strategies are of profound interest in life history because they directly impact offspring fitness and therefore are highly valuable for understanding population dynamics and informing management decisions. Yet, numerous questions about reproductive allocation patterns for wild populations of large mammals remain unanswered because of the challenges for measuring allocation in the wild. Using a nine-year longitudinal data set on life-history traits of mother–calf bison pairs, we identified sources of variation in relative maternal allocation (calf mass ratio on mother mass) and assessed the occurrence of reproductive costs associated with differential maternal allocation. We found that heavy mothers provided a lower allocation but still produced heavier calves than light mothers. Older females produced lighter calves and tended to decrease allocation as they aged, supporting the occurrence of reproductive senescence. Mothers that had produced a calf the previous year produced lighter calves and allocated less than mothers that did not lactate the previous year, revealing reproductive costs. However, greater maternal allocation did not reduce the probability of breeding in successive years, and the amount of allocation provided by a mother was positively correlated among the offspring she produced, illustrating individual heterogeneity. Although life-history studies are usually classified as either supporting costs of reproduction or individual quality, our study demonstrates that these contrasting evolutionary forces can shape variation within a single trait. Our work illustrates that many processes can coevolve within a population, emphasizing the need to integrate multiple concepts to better understand the evolution of life-history traits. With regard to management of bison herds, if the goal of culling programs is to select for animals with the best performance, this research suggests that managers should account for the condition and previous reproductive status of mothers when taking culling decisions on juvenile bison.
1 aHamel, S.1 aCraine, J.M.1 aTowne, E.G. uhttps://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/11-2181.102143nas a2200145 4500008004100000245009000041210006900131300001500200490000700215520164500222100001701867700002001884700001601904856007701920 2012 eng d00aThe roles of shifting and filtering in generating community-level flowering phenology0 aroles of shifting and filtering in generating communitylevel flo a1033 -10380 v353 aPlant phenologies are key components of community assembly and ecosystem function, yet we know little about how phenological patterns differ among ecosystems. Community-level phenological patterns may be driven by the filtering of species into communities based on their phenology or by intraspecific responses to local conditions that shift when species flower. To understand the relative roles of filtering and shifting on community-level phenological patterns we compared patterns of first flowering dates (FFD) for herbaceous species at Konza Prairie, KS, USA with those from the colder Fargo, ND, USA area and from Chinnor, England, which has a less continental climate. Comparing patterns of FFD supports that Konza's flowering patterns are potentially influenced both by filtering species that flower early in the growing season and by phenological shifting. Konza species flowering dates were earlier in the spring and later in the fall compared to Fargo, but were not shifted compared to Chinnor, which had a unique suite of early-flowering species. In all, comparing flowering phenology among three sites reveals that intraspecific responses to climate can generate phenological shifts that compress or stretch community-level phenological patterns, while novel niches in phenological space can also alter community-level patterns. Community flowering patterns related to climate suggest that climatic warming has the potential to further distribute flowering of the Konza flora over a longer period, but also could further open it to introductions of non-native species that have evolved to flower early in the season.
1 aCraine, J.M.1 aWolkovich, E.M.1 aTowne, E.G. uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/j.1600-0587.2012.07625.x02482nas a2200229 4500008004100000245009500041210006900136300001300205490000800218520174900226653002401975653001301999653002002012653001702032653003902049653002202088100002302110700001602133700002002149700001702169856006602186 2012 eng d00aRoot characteristics of C-4 grasses limit reliance on deep soil water in tallgrass prairie0 aRoot characteristics of C4 grasses limit reliance on deep soil w a385 -3940 v3553 aBackground C4 grass species in the mesic tallgrass prairie of central North America can exhibit both high root production and deep rooting in the soil profile (>2 m). Differences in root growth and the types of roots produced vary according to local environmental gradients and management practices. The production of deep roots in tallgrass prairie has been historically presumed as a mechanism for water uptake when surface soils are dry. Methods We examined changes in root biomass, total root length, root width, and theoretical hydraulic conductivity using roots collected from deep soil cores in upland and lowland topographic positions in grazed and ungrazed watersheds of the Konza Prairie Biological Station in north-eastern Kansas, USA. Results Root biomass, total root length, and theoretical hydraulic conductivity were highest in roots found in the top 20 cm of the soil profile, and then declined exponentially with increasing soil depth. Compared to grazed areas, ungrazed locations had more root biomass and total root length of roots in the most superficial soil layers. No differences in rooting profiles were present among topographic contrasts. Theoretical hydraulic conductivity of axial root xylem did not vary by topographic position or grazing contrasts, and declines in conductivity by depth were driven by changes in the number of vessels per stele, rather than changes in vessel size. Conclusions Irrespective of differences by grazing treatment or topographic position, significant reductions in root biomass, total root length, and theoretical hydraulic conductivity of grass roots at soil depths greater than 1 m suggest deep roots in this grassland have limited functional significance for water uptake.
10aAndropogon gerardii10aC4 grass10aMesic grassland10aRoot biomass10aTheoretical hydraulic conductivity10aTotal root length1 aNippert, Jesse, B.1 aWieme, R.A.1 aOcheltree, T.W.1 aCraine, J.M. uhttps://link.springer.com/article/10.1007%2Fs11104-011-1112-401558nas a2200181 4500008004100000245006500041210006100106300001500167490000800182520099700190100001701187700002301204700001701227700001701244700002101261700001701282856007701299 2012 eng d00aThe timing of climate variability and grassland productivity0 atiming of climate variability and grassland productivity a3401 -34050 v1093 aChanges in precipitation amount and variability have the potential to alter the structure and function of grasslands, but we know little about how changes in the timing of precipitation might affect grasslands. Here, we analyze long-term records from a tallgrass prairie to show that shifts in the timing of precipitation during the growing season have little effect on primary productivity or grass reproduction, but can greatly affect grazer performance. While greater late-season precipitation increases the weight gain of adult and young bison, greater mid-season precipitation decreases their weight gain. In addition, calving rates are lower after years with greater mid-season precipitation and higher after years with greater late-season precipitation. As well-timed drought can actually increase grazer weight gain and reproduction, it will be necessary to generate predictions of within-season distribution of precipitation to successfully forecast future grazer performance.
1 aCraine, J.M.1 aNippert, Jesse, B.1 aElmore, A.J.1 aSkibbe, A.M.1 aHutchinson, S.L.1 aBrunsell, N. uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/j.1600-0706.2012.20400.x02524nas a2200253 4500008004100000245009600041210006900137300001500206490000800221520175800229653001701987653001902004653002202023653001502045653001802060100001702078700002302095700001602118700001502134700001702149700001702166700002102183856006602204 2011 eng d00aFunctional consequences of climate-change induced plant species loss in a tallgrass prairie0 aFunctional consequences of climatechange induced plant species l a1109 -11170 v1653 aFuture climate change is likely to reduce the floristic diversity of grasslands. Yet the potential consequences of climate-induced plant species losses for the functioning of these ecosystems are poorly understood. We investigated how climate change might alter the functional composition of grasslands for Konza Prairie, a diverse tallgrass prairie in central North America. With species-specific climate envelopes, we show that a reduction in mean annual precipitation would preferentially remove species that are more abundant in the more productive lowland positions at Konza. As such, decreases in precipitation could reduce productivity not only by reducing water availability but by also removing species that inhabit the most productive areas and respond the most to climate variability. In support of this prediction, data on species abundance at Konza over 16 years show that species that are more abundant in lowlands than uplands are preferentially reduced in years with low precipitation. Climate change is likely to also preferentially remove species from particular functional groups and clades. For example, warming is forecast to preferentially remove perennials over annuals as well as Cyperaceae species. Despite these predictions, climate change is unlikely to unilaterally alter the functional composition of the tallgrass prairie flora, as many functional traits such as physiological drought tolerance and maximum photosynthetic rates showed little relationship with climate envelope parameters. In all, although climatic drying would indirectly alter grassland productivity through species loss patterns, the insurance afforded by biodiversity to ecosystem function is likely to be sustained in the face of climate change.
10abiogeography10aClimate change10aFunctional traits10aGrasslands10aKonza Prairie1 aCraine, J.M.1 aNippert, Jesse, B.1 aTowne, E.G.1 aTucker, S.1 aKembel, S.W.1 aSkibbe, A.M.1 aMcLauchlan, K.K. uhttps://link.springer.com/article/10.1007%2Fs00442-011-1938-801952nas a2200205 4500008004100000245010400041210006900145300001300214490000700227520132900234653001201563653001001575653001701585653001101602653001201613100002101625700001701646700001701663856006601680 2011 eng d00aInterannual variability of pollen productivity and transport in mid-North America from 1997 to 20090 aInterannual variability of pollen productivity and transport in a181 -1890 v273 aUnderstanding the causes of interannual variability in atmospheric pollen concentration is an important but elusive goal for public health and environmental change. We analyzed long-term daily records of pollen counts from urban Kansas City, Missouri, USA collected from 1997 to 2009 for three pollen groups: Ambrosia, Poaceae, and a third group which is mostly composed of arboreal pollen types. The annual pollen index varied from 8,368 to 80,822 over the thirteen-year period. Although Ambrosia pollen is often thought to be associated with droughts and disturbance, years with high Ambrosia pollen were associated with high summer precipitation to the south of Kansas City. Years with high Poaceae pollen were associated with high spring precipitation to the south of the city. In support of the southern influence to Kansas City pollen, Ambrosia and Poaceae pollen mostly arrived on southern winds. In contrast to the other two pollen groups, the arboreal pollen was most associated with growing season precipitation to the east of Kansas City, although it was still highest on days with southern winds. Based on the correlations with climate, the severity of an upcoming allergy season may be predicted with early-season precipitation data, while short-term severity can be forecast from local weather patterns.
10aclimate10agrass10aGreat Plains10aPollen10aRagweed1 aMcLauchlan, K.K.1 aBarnes, C.S.1 aCraine, J.M. uhttps://link.springer.com/article/10.1007%2Fs10453-010-9186-702128nas a2200145 4500008004100000245008100041210006900122300000900191490000600200520164100206100001701847700001701864700002301881856007801904 2011 eng d00aPhysiological drought tolerance and the structuring of tallgrass assemblages0 aPhysiological drought tolerance and the structuring of tallgrass a48 -0 v23 aDrought is a defining characteristic of many grasslands worldwide. Yet we have little understanding of how drought structures grassland communities and the degree to which physiological drought tolerance advantages plants in grasslands. We characterized physiological drought tolerance (Ψcrit) for a large number of species in a mesic grassland community (Konza Prairie, KS, USA). We then examined the relationships between Ψcrit and a number of other key functional traits, and tested whether physiological tolerance of drought underlay success across a number of ecological contrasts—topographic position, burn frequency, and grazing—with 17 years of abundance data. Physiological drought tolerance of Konza species covered almost the full range known to plants globally. Consistently, physiologically drought-tolerant species had thin roots, while associations with other traits were inconsistent across functional groups. In this mesic grassland, physiological drought tolerance appears to increase the abundance of plants in xeric uplands, but does not in the mesic lowlands. Physiological drought tolerance did not alter species responses to changes in burning or grazing. In contrast to Ψcrit, species with high root tissue density were more abundant in uplands and lowlands than species with low root tissue density largely irrespective of grazing or burning regimes. In all, drought appears to have a limited role in structuring the Konza plant community. As such, more severe or frequent droughts in the region would likely restructure the Konza plant community in ways that are currently not observable.
1 aTucker, S.S.1 aCraine, J.M.1 aNippert, Jesse, B. uhttps://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/ES11-00023.101647nas a2200205 4500008004100000245011300041210006900154300001300223490000700236520095200243653001401195653002601209653001801235653002401253653002801277653001201305100001701317700002001334856008701354 2011 eng d00aSoil moisture controls on temperature sensitivity of soil organic carbon decomposition for a mesic grassland0 aSoil moisture controls on temperature sensitivity of soil organi a455 -4570 v433 aWe examined relationships between soil moisture and the temperature sensitivity of decomposition of labile soil organic carbon at a central North American grassland. For soils collected from shallow, xeric uplands, temperature sensitivity was greatest at intermediate soil moisture. For soils collected from the deeper, mesic lowlands, temperature sensitivity increased with increasing soil moisture. For example, lowland soils incubated at 75% WHC exhibited an apparent activation energy (Ea) that was 15 kJ mol−1 greater than soils incubated at 30% WHC, the equivalent of a Q10 of 2.8 vs. 2.3. Although further research is still needed to understand why moisture–temperature sensitivity relationships would differ between topographic positions, the magnitude of the soil moisture effect is large enough to alter soil C budgets and should be considered explicitly when predicting ecosystem responses to global change scenarios.
10agrassland10aMicrobial respiration10asoil moisture10aSoil organic carbon10aTemperature sensitivity10aWarming1 aCraine, J.M.1 aGelderman, T.M. uhttps://www.sciencedirect.com/science/article/abs/pii/S0038071710003949?via%3Dihub02015nas a2200157 4500008004100000245004900041210004900090300001500139490000700154520155200161100001701713700001701730700001601747700001701763856007701780 2010 eng d00aClimate change and cattle nutritional stress0 aClimate change and cattle nutritional stress a2901 -29110 v163 aOwing to the complex interactions among climate, plants, cattle grazing, and land management practices, the impacts of climate change on cattle have been hard to predict. Predicting future grassland ecosystem functioning relies on understanding how changes in climate alter the quantity of forage produced, but also forage quality. Plant protein, which is a function of plant nitrogen concentrations, and digestible energy limit the performance of herbivores when in short supply; moreover, deficiencies can be expensive to mitigate. To better understand how changes in temperature and precipitation would affect forage protein and energy availability, we analyzed over 21 000 measurements of cattle fecal chemistry acquired over 14 years in the continental US. Our analysis of patterns in forage quality among ecologically defined regions revealed that increasing temperature and declining precipitation decreased dietary crude protein and digestible organic matter for regions with continental climates. Within regions, quality also declined with increased temperature; however, the effects of precipitation were mixed. Any future increases in precipitation would be unlikely to compensate for the declines in forage quality that accompany projected temperature increases. As a result, cattle are likely to experience greater nutritional stress in the future. If these geographic patterns hold as a proxy for future climates, agriculture will require increased supplemental feeds or the consequence will be a decrease in livestock growth.
1 aCraine, J.M.1 aElmore, A.J.1 aOlson, K.C.1 aTolleson, D. uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2009.02060.x02131nas a2200145 4500008004100000245009200041210006900133300001500202490000700217520163100224100001701855700001601872700002301888856007401911 2010 eng d00aClimate controls on grass culm production over a quarter century in a tallgrass prairie0 aClimate controls on grass culm production over a quarter century a2132 -21400 v913 aThe flowering of grasses is a process critical to plant population dynamics and genetics, herbivore performance, and human health. To better understand the climate factors governing grass flowering, we analyzed the patterns of culm production over 25 years for three perennial tallgrass prairie species at Konza Prairie in Kansas, USA. The three species (Andropogon gerardii, Sorghastrum nutans, and Schizachyrium scoparium) all utilize the C4 photosynthetic pathway and were measured annually at the same locations for the past 25 years in an annually burned watershed. Culm production of all three species increased with higher growing-season soil moisture and precipitation but differed in their responses to water availability at different times during the growing season. Relative to Andropogon, Sorghastrum responded more to precipitation early in the growing season, and Schizachyrium responded more to precipitation late in the growing season. Flowering by each species also revealed a threshold relationship with late-season soil moisture at ~1 m depth, which likely is a proxy for season-long water balance. Although flowering can be influenced by conditions antecedent to the current growing season, neither soil moisture nor precipitation during the previous year influenced flowering over the 25-year period. Flowering culm production averaged 9% and 7% of total graminoid aboveground net primary production (ANPP) in the uplands and lowlands, respectively. Interannual variation in ANPP correlated only with Sorghastrum flowering, suggesting a predominant role of the species in ANPP responses to climate.
1 aCraine, J.M.1 aTowne, E.G.1 aNippert, Jesse, B. uhttps://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/09-1242.102295nas a2200205 4500008004100000245015700041210006900198300001300267490000800280520160800288653001201896653002201908653001501930653001201945653001801957653001501975100001701990700001602007856006602023 2010 eng d00aHigh leaf tissue density grassland species consistently more abundant across topographic and disturbance contrasts in a North American tallgrass prairie0 aHigh leaf tissue density grassland species consistently more abu a193 -2030 v3373 aUnderstanding the coupling between plant functional traits and abundance provides insight into the often hidden forces that structure plant communities. To better understand the coupling between leaf traits and abundance of grassland species in a mesic North American grassland, we measured specific leaf area (SLA) and its two components, tissue density and thickness for 125 grassland species. Plants with high tissue density were more abundant over a 17-year period across a range of environments: uplands, grazed and ungrazed watersheds, and frequently and infrequently burned watersheds. The consistent relationships between leaf tissue density and abundance across ecological contrasts imply that belowground resource availability constrains community composition independent of grazing and burning regimes. Leaf tissue density did not explain species abundance in lowlands, where belowground resources are the highest. Neither did it explain the differential abundance of species between grazing or fire frequency contrasts, suggesting that changes in burning or grazing select for species based on other traits. Relative to leaf tissue density, SLA was a poor predictor of abundance, reinforcing a long-observed—but often ignored—call that measurements of SLA need to be coupled with thickness measurements in order to effectively predict the performance of species. More generally, future research needs to investigate which belowground resources control community composition in the grassland and whether the importance of water or nutrients change with burning and grazing.
10aburning10aFunctional traits10aGrasslands10aGrazing10aKonza Prairie10atopography1 aCraine, J.M.1 aTowne, E.G. uhttps://link.springer.com/article/10.1007%2Fs11104-010-0515-y01691nas a2200193 4500008004100000245008200041210006900123300001100192490000800203520110700211653001701318653001501335653001301350653001501363653001801378100001701396700001801413856006601431 2010 eng d00aPlant nitrogen and phosphorus limitation in 98 North American grassland soils0 aPlant nitrogen and phosphorus limitation in 98 North American gr a73 -840 v3343 aThe availability of nutrients is a critical determinant of ecological dynamics in grasslands, but the relationships between soil resource availability and nutrient limitation across ecosystems are not clear. To better understand how soil nutrient availability determines nutrient limitation in vegetation, we grew the same species of grass (Schizachyrium scoparium) in 98 North American grassland soils and fertilized them factorially with nitrogen (N) and phosphorus (P). On average adding N, P, and the two nutrients together increased biomass relative to unfertilized plants by 81%, 22%, and 131%, respectively. Plants grown on low-P soils were not primarily limited by P. Instead, these plants were colimited by N and P, while plants grown on high-P soils were primarily limited by N and only secondarily limited by P. Limitation was not predicted by total soil N. The preponderance of colimitation between N and P on low-P soils suggests that low P availability alters the N cycle to constrain supplies to plants such that N and P are made available in proportion to their demand by plants.
10aColimitation10aGrasslands10anitrogen10aPhosphorus10astoichiometry1 aCraine, J.M.1 aJackson, R.D. uhttps://link.springer.com/article/10.1007%2Fs11104-009-0237-102026nas a2200169 4500008004100000245011800041210006900159300001500228490000800243520142900251100002101680700001901701700001701720700002001737700001701757856008201774 2010 eng d00aThirteen decades of foliar isotopes indicate declining nitrogen availability in central North American grasslands0 aThirteen decades of foliar isotopes indicate declining nitrogen a1135 -11450 v1873 a•Humans are increasing both the deposition of reactive nitrogen (N) and concentrations of atmospheric CO2 on Earth, but the combined effects on terrestrial ecosystems are not clear. In the absence of historical records, it is difficult to know if N availability is currently increasing or decreasing on regional scales. •To determine the nature and timing of past changes in grassland ecosystem dynamics, we measured the composition of stable carbon (C) and N isotopes in leaf tissue from 545 herbarium specimens of 24 vascular plant species collected in Kansas, USA from 1876 to 2008. We also parameterized a simple model of the terrestrial N cycle coupled with a stable isotope simulator to constrain processes consistent with observed patterns. •A prolonged decline in foliar N concentrations began in 1926, while a prolonged decline in foliar δ15N values began in 1940. Changes in the difference between foliar and atmospheric C isotopes reveal slightly increased photosynthetic water use efficiency since 1876. •The declines in foliar N concentrations and foliar δ15N suggest declining N availability in these grasslands during the 20th century despite decades of anthropogenic N deposition. Our results are consistent with progressive-nitrogen-limitation-type hypotheses where declines in N availability are driven by increased ecosystem N storage as a result of increased atmospheric CO2.
1 aMcLauchlan, K.K.1 aFerguson, C.J.1 aWilson, I.E.1 aOcheltree, T.W.1 aCraine, J.M. uhttps://nph.onlinelibrary.wiley.com/doi/full/10.1111/j.1469-8137.2010.03322.x01962nas a2200169 4500008004100000245009300041210006900134300001300203490000600216520143000222653002001652653002201672100001701694700001501711700002101726856004501747 2010 eng d00aWidespread coupling between the rate and temperature sensitivity of organic matter decay0 aWidespread coupling between the rate and temperature sensitivity a854 -8570 v33 aMicrobial breakdown of soil organic matter influences the potential for terrestrial ecosystems to sequester carbon, and the amount of carbon dioxide released to the atmosphere1, 2, 3, 4. Predicting the sensitivity of microbial decomposition to temperature change is therefore critical to predicting future atmospheric carbon dioxide concentrations and feedbacks to anthropogenic warming5. According to enzyme kinetics, the more biogeochemically recalcitrant the organic matter, the greater the temperature sensitivity of microbial respiration6, 7, 8. Here, we measured the temperature sensitivity of microbial respiration in soils from 28 sites in North America, ranging from Alaska to Puerto Rico, to test the generality of this principle. We show that the lower the rate of respiration at a reference temperature of 20 °C—and thus the more biogeochemically recalcitrant the organic matter—the greater the temperature sensitivity of soil respiration. We compiled our findings with those from other studies, encapsulating a range of environments, and show that this relationship holds across multiple scales and soil types. Although physico-chemical protection of soil organic matter and substrate availability will also influence the temperature sensitivity of decomposition, we suggest that biogeochemically recalcitrant organic matter will respond the most sensitively to anticipated warming.
10aBiogeochemistry10aMicrobial ecology1 aCraine, J.M.1 aFierer, N.1 aMcLauchlan, K.K. uhttps://www.nature.com/articles/ngeo100902011nas a2200157 4500008004100000245009000041210006900131300001300200490000700213520148500220100001701705700001601722700001901738700001901757856007701776 2009 eng d00aConsequences of climate variability for the performance of bison in tallgrass prairie0 aConsequences of climate variability for the performance of bison a772 -7790 v153 aClimate variability is a major structuring factor in grassland ecosystems, yet there is great uncertainty in how changes in precipitation affect grazing herbivores. We determined how interannual variation in the timing and magnitude of precipitation affected the weight gain of free-roaming bison in their first and second year. Bison weights were analyzed for 14 years for Konza Prairie, Kansas, and 12 years for Tallgrass Prairie Preserve, Oklahoma. Greater late-summer precipitation increased bison weight gain. For every 100 mm precipitation, weight gain increased 6.4–15.3 kg depending on age classes and site. In contrast, greater midsummer precipitation decreased weight gain. For every additional 100 mm precipitation, weight decreased 9.7–17.3 kg depending on age class and site. The decreased weight gain of bison with greater midsummer precipitation was associated with increased grass stem production during the period for each of three dominant grasses at Konza Prairie. Although greater stem production increases the quantity of aboveground biomass, it should decrease the overall nutritional quality of biomass to grazers, which would reduce weight gain. With offsetting effects of mid- and late-summer precipitation on weight gain, these results show that predicting the effects of climate change on grazers must incorporate both the timing and magnitude of changes in precipitation and their effects on both the quantity and quality of biomass.
1 aCraine, J.M.1 aTowne, E.G.1 aJoern, Anthony1 aHamilton, R.G. uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2008.01769.x01428nas a2200217 4500008004100000245009400041210006900135300001300204490000700217520072800224653001400952653002600966653002400992653002801016653001201044100001701056700001401073700002101087700001501108856008701123 2009 eng d00aLandscape-level variation in temperature sensitivity of soil organic carbon decomposition0 aLandscapelevel variation in temperature sensitivity of soil orga a373 -3750 v423 aWe examined landscape-level variation in temperature sensitivity of labile SOC across 71 sites at a central North American grassland. The observed range in activation energy of decomposition (Ea), an index of temperature sensitivity, was as great at the landscape scale as has been observed at the continental scale. Ea was lower for soils with more labile C, consistent with the ‘Carbon quality-temperature’ hypothesis. Soil pH explained 67% of the variation in Ea. Although there are strong environmental correlates with the Ea of SOC decomposition at landscape scales, the amount of variation within landscapes could confound regional- to global-scale predictions of the response of soil C to warming.
10agrassland10aMicrobial respiration10aSoil organic carbon10aTemperature sensitivity10aWarming1 aCraine, J.M.1 aSpurr, R.1 aMcLauchlan, K.K.1 aFierer, N. uhttps://www.sciencedirect.com/science/article/abs/pii/S0038071709004015?via%3Dihub01885nas a2200169 4500008004100000245009300041210006900134300001100203490000700214520129200221100001701513700001401530700001501544700001901559700001801578856011901596 2005 eng d00aEnvironmental constraints on a global relationship among leaf and root traits of grasses0 aEnvironmental constraints on a global relationship among leaf an a12 -190 v863 aUncertainties regarding the relationships between leaf and root traits have impeded an integrated understanding of plant evolution and the efficient parameterization of ecosystem models. We measured key root and leaf traits of grasses from 77 sites in four grassland regions of the world (New Zealand, Australia, South Africa, North America). Within each region, the relationships among leaf traits paralleled those among root traits. Plants with low root or leaf N concentrations had roots or leaves with high tissue density, high lignin concentrations, low amount of mass that was soluble in a neutral detergent solution, large diameter/thickness, and were less enriched in 15N. Yet, whether comparing plants within a region or among all four regions, there was little relationship between root traits and leaf traits, except for a positive relationship between root and leaf N concentration and between root and leaf δ15N. At the global scale, factors such as soil freezing and the type of nutrient limitation appear to determine relationships among leaves and roots. C4 grasses not only had lower leaf N concentrations than C3 grasses but also lower root N concentrations. When compared at the same root N concentration, C4 grasses had greater leaf N concentrations than C3 grasses.1 aCraine, J.M.1 aLee, W.G.1 aBond, W.J.1 aWillians, R.J.1 aJohnson, L.C. uhttp://lter.konza.ksu.edu/content/environmental-constraints-global-relationship-among-leaf-and-root-traits-grasses