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Polley HW, Derner JD, Jackson RB, Wilsey BJ, Fay PA. Impacts of climate change drivers on C4 grassland productivity: scaling driver effects through the plant community. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3415-3424. [PMID: 24501178 DOI: 10.1093/jxb/eru009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Climate change drivers affect plant community productivity via three pathways: (i) direct effects of drivers on plants; (ii) the response of species abundances to drivers (community response); and (iii) the feedback effect of community change on productivity (community effect). The contribution of each pathway to driver-productivity relationships depends on functional traits of dominant species. We used data from three experiments in Texas, USA, to assess the role of community dynamics in the aboveground net primary productivity (ANPP) response of C4 grasslands to two climate drivers applied singly: atmospheric CO2 enrichment and augmented summer precipitation. The ANPP-driver response differed among experiments because community responses and effects differed. ANPP increased by 80-120g m(-2) per 100 μl l(-1) rise in CO2 in separate experiments with pasture and tallgrass prairie assemblages. Augmenting ambient precipitation by 128mm during one summer month each year increased ANPP more in native than in exotic communities in a third experiment. The community effect accounted for 21-38% of the ANPP CO2 response in the prairie experiment but little of the response in the pasture experiment. The community response to CO2 was linked to species traits associated with greater soil water from reduced transpiration (e.g. greater height). Community effects on the ANPP CO2 response and the greater ANPP response of native than exotic communities to augmented precipitation depended on species differences in transpiration efficiency. These results indicate that feedbacks from community change influenced ANPP-driver responses. However, the species traits that regulated community effects on ANPP differed from the traits that determined how communities responded to drivers.
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Martin LM, Polley HW, Daneshgar PP, Harris MA, Wilsey BJ. Biodiversity, photosynthetic mode, and ecosystem services differ between native and novel ecosystems. Oecologia 2014; 175:687-97. [DOI: 10.1007/s00442-014-2911-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 10/28/2013] [Indexed: 11/25/2022]
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Gross K, Cardinale BJ, Fox JW, Gonzalez A, Loreau M, Wayne Polley H, Reich PB, van Ruijven J. Species Richness and the Temporal Stability of Biomass Production: A New Analysis of Recent Biodiversity Experiments. Am Nat 2014; 183:1-12. [DOI: 10.1086/673915] [Citation(s) in RCA: 254] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Wilsey BJ, Daneshgar PP, Hofmockel K, Polley HW. Invaded grassland communities have altered stability-maintenance mechanisms but equal stability compared to native communities. Ecol Lett 2013; 17:92-100. [DOI: 10.1111/ele.12213] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 08/14/2013] [Accepted: 10/07/2013] [Indexed: 11/28/2022]
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Briske DD, Bestelmeyer BT, Brown JR, Fuhlendorf SD, Wayne Polley H. The Savory Method Can Not Green Deserts or Reverse Climate Change. ACTA ACUST UNITED AC 2013. [DOI: 10.2111/rangelands-d-13-00044.1] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Rico C, Pittermann J, Polley HW, Aspinwall MJ, Fay PA. The effect of subambient to elevated atmospheric CO₂ concentration on vascular function in Helianthus annuus: implications for plant response to climate change. THE NEW PHYTOLOGIST 2013; 199:956-965. [PMID: 23731256 DOI: 10.1111/nph.12339] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Accepted: 04/16/2013] [Indexed: 06/02/2023]
Abstract
Plant gas exchange is regulated by stomata, which coordinate leaf-level water loss with xylem transport. Stomatal opening responds to internal concentrations of CO₂ in the leaf, but changing CO₂ can also lead to changes in stomatal density that influence transpiration. Given that stomatal conductance increases under subambient concentrations of CO₂ and, conversely, that plants lose less water at elevated concentrations, can downstream effects of atmospheric CO₂ be observed in xylem tissue? We approached this problem by evaluating leaf stomatal density, xylem transport, xylem anatomy and resistance to cavitation in Helianthus annuus plants grown under three CO₂ regimes ranging from pre-industrial to elevated concentrations. Xylem transport, conduit size and stomatal density all increased at 290 ppm relative to ambient and elevated CO₂ concentrations. The shoots of the 290-ppm-grown plants were most vulnerable to cavitation, whereas xylem cavitation resistance did not differ in 390- and 480-ppm-grown plants. Our data indicate that, even as an indirect driver of water loss, CO₂ can affect xylem structure and water transport by coupling stomatal and xylem hydraulic functions during plant development. This plastic response has implications for plant water use under variable concentrations of CO₂, as well as the evolution of efficient xylem transport.
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Polley HW, Isbell FI, Wilsey BJ. Plant functional traits improve diversity-based predictions of temporal stability of grassland productivity. OIKOS 2013. [DOI: 10.1111/j.1600-0706.2013.00338.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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de Mazancourt C, Isbell F, Larocque A, Berendse F, De Luca E, Grace JB, Haegeman B, Wayne Polley H, Roscher C, Schmid B, Tilman D, van Ruijven J, Weigelt A, Wilsey BJ, Loreau M. Predicting ecosystem stability from community composition and biodiversity. Ecol Lett 2013; 16:617-25. [PMID: 23438189 DOI: 10.1111/ele.12088] [Citation(s) in RCA: 213] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 11/08/2012] [Accepted: 01/15/2013] [Indexed: 11/30/2022]
Abstract
As biodiversity is declining at an unprecedented rate, an important current scientific challenge is to understand and predict the consequences of biodiversity loss. Here, we develop a theory that predicts the temporal variability of community biomass from the properties of individual component species in monoculture. Our theory shows that biodiversity stabilises ecosystems through three main mechanisms: (1) asynchrony in species' responses to environmental fluctuations, (2) reduced demographic stochasticity due to overyielding in species mixtures and (3) reduced observation error (including spatial and sampling variability). Parameterised with empirical data from four long-term grassland biodiversity experiments, our prediction explained 22-75% of the observed variability, and captured much of the effect of species richness. Richness stabilised communities mainly by increasing community biomass and reducing the strength of demographic stochasticity. Our approach calls for a re-evaluation of the mechanisms explaining the effects of biodiversity on ecosystem stability.
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Polley HW, Jin VL, Fay PA. Feedback from plant species change amplifies CO2 enhancement of grassland productivity. GLOBAL CHANGE BIOLOGY 2012; 18:2813-2823. [PMID: 24501059 DOI: 10.1111/j.1365-2486.2012.02735.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 04/20/2012] [Indexed: 06/03/2023]
Abstract
Dynamic global vegetation models simulate feedbacks of vegetation change on ecosystem processes, but direct, experimental evidence for feedbacks that result from atmospheric CO2 enrichment is rare. We hypothesized that feedbacks from species change would amplify the initial CO2 stimulation of aboveground net primary productivity (ANPP) of tallgrass prairie communities. Communities of perennial forb and C4 grass species were grown for 5 years along a field CO2 gradient (250-500 μL L(-1) ) in central Texas USA on each of three soil types, including upland and lowland clay soils and a sandy soil. CO2 enrichment increased community ANPP by 0-117% among years and soils and increased the contribution of the tallgrass species Sorghastrum nutans (Indian grass) to community ANPP on each of the three soil types. CO2 -induced changes in ANPP and Sorghastrum abundance were linked. The slope of ANPP-CO2 regressions increased between initial and final years on the two clay soils because of a positive feedback from the increase in Sorghastrum fraction. This feedback accounted for 30-60% of the CO2 -mediated increase in ANPP on the upland and lowland clay soils during the final 3 years and 1 year of the experiment, respectively. By contrast, species change had little influence on the ANPP-CO2 response on the sandy soil, possibly because Sorghastrum increased largely at the expense of a functionally similar C4 grass species. By favoring a mesic C4 tall grass, CO2 enrichment approximately doubled the initial enhancement of community ANPP on two clay soils. The CO2 -stimulation of grassland productivity may be significantly underestimated if feedbacks from plant community change are not considered.
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Wilsey BJ, Daneshgar PP, Polley HW. Biodiversity, phenology and temporal niche differences between native- and novel exotic-dominated grasslands. PERSPECTIVES IN PLANT ECOLOGY, EVOLUTION AND SYSTEMATICS 2011; 13:265-276. [PMID: 0 DOI: 10.1016/j.ppees.2011.07.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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Kelley AM, Fay PA, Polley HW, Gill RA, Jackson RB. Atmospheric CO2and soil extracellular enzyme activity: a meta-analysis and CO2gradient experiment. Ecosphere 2011. [DOI: 10.1890/es11-00117.1] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Manzoni S, Katul G, Fay PA, Polley HW, Porporato A. Modeling the vegetation–atmosphere carbon dioxide and water vapor interactions along a controlled CO2 gradient. Ecol Modell 2011. [DOI: 10.1016/j.ecolmodel.2010.10.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Polley HW, Phillips RL, Frank AB, Bradford JA, Sims PL, Morgan JA, Kiniry JR. Variability in Light-Use Efficiency for Gross Primary Productivity on Great Plains Grasslands. Ecosystems 2010. [DOI: 10.1007/s10021-010-9389-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Wilsey BJ, Teaschner TB, Daneshgar PP, Isbell FI, Polley HW. Biodiversity maintenance mechanisms differ between native and novel exotic-dominated communities. Ecol Lett 2009; 12:432-42. [PMID: 19379137 DOI: 10.1111/j.1461-0248.2009.01298.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In many systems, native communities are being replaced by novel exotic-dominated ones. We experimentally compared species diversity decline between nine-species grassland communities under field conditions to test whether diversity maintenance mechanisms differed between communities containing all exotic or all native species using a pool of 40 species. Aboveground biomass was greater in exotic than native plots, and this difference was larger in mixtures than in monocultures. Species diversity declined more in exotic than native communities and declines were explained by different mechanisms. In exotic communities, overyielding species had high biomass in monoculture and diversity declined linearly as this selection effect increased. In native communities, however, overyielding species had low biomass in monoculture and there was no relationship between the selection effect and diversity decline. This suggests that, for this system, yielding behaviour is fundamentally different between presumably co-evolved natives and coevolutionarily naive exotic species, and that native-exotic status is important to consider.
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Isbell FI, Polley HW, Wilsey BJ. Biodiversity, productivity and the temporal stability of productivity: patterns and processes. Ecol Lett 2009; 12:443-51. [PMID: 19379138 DOI: 10.1111/j.1461-0248.2009.01299.x] [Citation(s) in RCA: 198] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Theory predicts that the temporal stability of productivity, measured as the ratio of the mean to the standard deviation of community biomass, increases with species richness and evenness. We used experimental species mixtures of grassland plants to test this hypothesis and identified the mechanisms involved. Additionally, we tested whether biodiversity, productivity and temporal stability were similarly influenced by particular types of species interactions. We found that productivity was less variable among years in plots planted with more species. Temporal stability did not depend on whether the species were planted equally abundant (high evenness) or not (realistically low evenness). Greater richness increased temporal stability by increasing overyielding, asynchrony of species fluctuations and statistical averaging. Species interactions that favoured unproductive species increased both biodiversity and temporal stability. Species interactions that resulted in niche partitioning or facilitation increased both productivity and temporal stability. Thus, species interactions can promote biodiversity and ecosystem services.
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Isbell FI, Polley HW, Wilsey BJ. Species interaction mechanisms maintain grassland plant species diversity. Ecology 2009; 90:1821-30. [DOI: 10.1890/08-0514.1] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Wayne Polley H, Wilsey BJ, Derner JD. Dominant species constrain effects of species diversity on temporal variability in biomass production of tallgrass prairie. OIKOS 2007. [DOI: 10.1111/j.2007.0030-1299.16080.x] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Wayne Polley H, Wilsey BJ, Tischler CR. Species abundances influence the net biodiversity effect in mixtures of two plant species. Basic Appl Ecol 2007. [DOI: 10.1016/j.baae.2006.02.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Wilsey BJ, Polley HW. Aboveground productivity and root–shoot allocation differ between native and introduced grass species. Oecologia 2006; 150:300-9. [PMID: 16927104 DOI: 10.1007/s00442-006-0515-z] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Accepted: 07/13/2006] [Indexed: 11/26/2022]
Abstract
Plant species in grasslands are often separated into groups (C(4) and C(3) grasses, and forbs) with presumed links to ecosystem functioning. Each of these in turn can be separated into native and introduced (i.e., exotic) species. Although numerous studies have compared plant traits between the traditional groups of grasses and forbs, fewer have compared native versus introduced species. Introduced grass species, which were often introduced to prevent erosion or to improve grazing opportunities, have become common or even dominant species in grasslands. By virtue of their abundances, introduced species may alter ecosystems if they differ from natives in growth and allocation patterns. Introduced grasses were probably selected nonrandomly from the source population for forage (aboveground) productivity. Based on this expectation, aboveground production is predicted to be greater and root mass fraction to be smaller in introduced than native species. We compared root and shoot distribution and tissue quality between introduced and native C(4) grass species in the Blackland Prairie region of Central Texas, USA, and then compared differences to the more well-studied divergence between C(4) grasses and forbs. Comparisons were made in experimental monocultures planted with equal-sized transplants on a common soil type and at the same density. Aboveground productivity and C:N ratios were higher, on average, in native grasses than in native forbs, as expected. Native and introduced grasses had comparable amounts of shallow root biomass and tissue C:N ratios. However, aboveground productivity and total N were lower and deep root biomass and root mass fraction were greater in native than introduced grasses. These differences in average biomass distribution and N could be important to ecosystems in cases where native and introduced grasses have been exchanged. Our results indicate that native-introduced status may be important when interpreting species effects on grassland processes like productivity and plant N accumulation.
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Wayne Polley H, J. Wilsey B, D. Derner J, B. Johnson H, Sanabria J. Early-successional plants regulate grassland productivity and species composition: a removal experiment. OIKOS 2006. [DOI: 10.1111/j.2006.0030-1299.14267.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Gill RA, Anderson LJ, Polley HW, Johnson HB, Jackson RB. Potential nitrogen constraints on soil carbon sequestration under low and elevated atmospheric CO2. Ecology 2006. [PMID: 16634295 DOI: 10.2307/20068908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The interaction between nitrogen cycling and carbon sequestration is critical in predicting the consequences of anthropogenic increases in atmospheric CO2 (hereafter, Ca). The progressive N limitation (PNL) theory predicts that carbon sequestration in plants and soils with rising Ca may be constrained by the availability of nitrogen in many ecosystems. Here we report on the interaction between C and N dynamics during a four-year field experiment in which an intact C3/C4 grassland was exposed to a gradient in Ca from 200 to 560 micromol/mol. There were strong species effects on decomposition dynamics, with C loss positively correlated and N mineralization negatively correlated with Ca for litter of the C3 forb Solanum dimidiatum, whereas decomposition of litter from the C4 grass Bothriochloa ischaemum was unresponsive to Ca. Both soil microbial biomass and soil respiration rates exhibited a nonlinear response to Ca, reaching a maximum at approximately 440 micromol/mol Ca. We found a general movement of N out of soil organic matter and into aboveground plant biomass with increased Ca. Within soils we found evidence of C loss from recalcitrant soil C fractions with narrow C:N ratios to more labile soil fractions with broader C:N ratios, potentially due to decreases in N availability. The observed reallocation of N from soil to plants over the last three years of the experiment supports the PNL theory that reductions in N availability with rising Ca could initially be overcome by a transfer of N from low C:N ratio fractions to those with higher C:N ratios. Although the transfer of N allowed plant production to increase with increasing Ca, there was no net soil C sequestration at elevated Ca, presumably because relatively stable C is being decomposed to meet microbial and plant N requirements. Ultimately, if the C gained by increased plant production is rapidly lost through decomposition, the shift in N from older soil organic matter to rapidly decomposing plant tissue may limit net C sequestration with increased plant production.
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Gill RA, Anderson LJ, Polley HW, Johnson HB, Jackson RB. POTENTIAL NITROGEN CONSTRAINTS ON SOIL CARBON SEQUESTRATION UNDER LOW AND ELEVATED ATMOSPHERIC CO2. Ecology 2006; 87:41-52. [PMID: 16634295 DOI: 10.1890/04-1696] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The interaction between nitrogen cycling and carbon sequestration is critical in predicting the consequences of anthropogenic increases in atmospheric CO2 (hereafter, Ca). The progressive N limitation (PNL) theory predicts that carbon sequestration in plants and soils with rising Ca may be constrained by the availability of nitrogen in many ecosystems. Here we report on the interaction between C and N dynamics during a four-year field experiment in which an intact C3/C4 grassland was exposed to a gradient in Ca from 200 to 560 micromol/mol. There were strong species effects on decomposition dynamics, with C loss positively correlated and N mineralization negatively correlated with Ca for litter of the C3 forb Solanum dimidiatum, whereas decomposition of litter from the C4 grass Bothriochloa ischaemum was unresponsive to Ca. Both soil microbial biomass and soil respiration rates exhibited a nonlinear response to Ca, reaching a maximum at approximately 440 micromol/mol Ca. We found a general movement of N out of soil organic matter and into aboveground plant biomass with increased Ca. Within soils we found evidence of C loss from recalcitrant soil C fractions with narrow C:N ratios to more labile soil fractions with broader C:N ratios, potentially due to decreases in N availability. The observed reallocation of N from soil to plants over the last three years of the experiment supports the PNL theory that reductions in N availability with rising Ca could initially be overcome by a transfer of N from low C:N ratio fractions to those with higher C:N ratios. Although the transfer of N allowed plant production to increase with increasing Ca, there was no net soil C sequestration at elevated Ca, presumably because relatively stable C is being decomposed to meet microbial and plant N requirements. Ultimately, if the C gained by increased plant production is rapidly lost through decomposition, the shift in N from older soil organic matter to rapidly decomposing plant tissue may limit net C sequestration with increased plant production.
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Polley HW, Derner JD, Wilsey BJ. Patterns of Plant Species Diversity in Remnant and Restored Tallgrass Prairies. Restor Ecol 2005. [DOI: 10.1111/j.1526-100x.2005.00060.x] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Derner JD, Schuman GE, Jawson M, Shafer SR, Morgan JA, Polley HW, Runion GB, Prior SA, Torbert HA, Rogers HH, Bunce J, Ziska L, White JW, Franzluebbers AJ, Reeder JD, Venterea RT, Harper LA. USDA-ARS Global Change Research on Rangelands and Pasturelands. ACTA ACUST UNITED AC 2005. [DOI: 10.2111/1551-501x(2005)27[36:ugcror]2.0.co;2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Wilsey BJ, Polley HW. REALISTICALLY LOW SPECIES EVENNESS DOES NOT ALTER GRASSLAND SPECIES-RICHNESS–PRODUCTIVITY RELATIONSHIPS. Ecology 2004. [DOI: 10.1890/04-0245] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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