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Photosynthetic and Respiratory Acclimation to Experimental Warming for Four SpeCies in a tallgrass prairie Ecosystem

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Journal of Integrative Plant Biology 2007年第3期49卷 270-281页

作者： Xuhui Zhou Xiaozhong Liu Linda L. Wallace Yiqi Luo Department of Botany and Microbiology University of Oklahoma Norman Oklahoma 73019 USA

Global temperature has been Increased by 0.6 ℃ over the past century and is predicted to Increase by 1.4-5.8 ℃ by the end of this century. It is unclear what impacts global warming will have on tallgrass species. In the present study, we examined leaf net photosynthetic rate （P.） and leaf respiration rate in darkness （Rd） of Aster erlcoldes （L.） Nesom, Ambrosia psllostachya DC., Helianthus mollis Lam., and Sorghastrum nutans （L.） Nash In response to experimental warming in a tallgrass prairie ecosystem of the Great Plains, USA, in the autumn （fall） of 2000 and through 2001. Warming has been Implemented with infrared heaters since 21 November 1999. The P. increased significantly In spring, decreased in early fall, and did not change in summer and late fall in the four species under warming compared with control. The Rd of the four species increased significantly until mid-summer and then did not change under warming. Measured temperature-response curves of P. showed that warming Increased the optimum temperature of P. （Topt） by 2.32 and 4.59 ℃ for H. mollis and S. nutans, respectively, in August, whereas there were no changes in May and September, and A. ericoldes and A. psllostachya also showed no changes in any of the 3 months. However, P. at optimum temperature （Popt） showed downregulation in September and no regulation in May and August for all four species. The temperature-response curves of Rd Illustrate that the temperature sensitivity of Rd, Q10, was lower in the warmed plots compared with the control plots, except for A. ericoides in August, whereas there were no changes In May and September for all four species. The results of the present study indicate that photosynthetic and respiratory acclimation varies with species and among seasons, occurring In the mid-growing season and not in the early and late growing seasons.

关键词： acclimation Ambrosia psilostachya climatic warming photosynthesis respiration Sorghastrum nutans tallgrass prairie temperature

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Tornado effects on damage,resprouting and spatial heterogeneity in the Cross Timbers ecotone of Oklahoma,USA

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Journal of Plant Ecology 2010年第3期3卷 157-163页

作者： Randall W.Myster Michael P.Malahy Biology Department Oklahoma State UniversityOklahoma CityOK 73107USA Botany Department Oklahoma State UniversityStillwaterOK 74078USA

Aims In order to better understand how tornados structure the ecotone between eastern deciduous forest and tallgrass prairie,we sampled trees in a recent tornado blowdown area and in the adjacent undisturbed *** are part of the Cross Timbers ecotone of Osage County,Northeastern Oklahoma,*** We set up a 1-ha square plot in each area and sampled all tree stems at least 50 cm tall where stems were identified to species and measured for size and spatial location in both *** the stems in the blowdown plot,we also scored damage and *** then used the spatial location data to compute the spatial heterogeneity and degree of clumping in both *** Findings Significant clumping was observed in the control forest at the small spatial scale of 1–8 m and at the medium spatial scale of 30–36 *** blowdown area:showed domination by post oak(Quercus stellata)with small stems,branch damage and stem resprouting above 1 m most common;had no trees that either lost their leaves without branch or stem damage or lived without some sort of resprouting,had a significant negative correlation between damage and resprouting and clumped only at small spatial scales for stems of medium size,for stems with branch damage and for stems that resprouted at or below 1 m *** conclude that in addition to largely eliminating a forest’s spatial heterogeneity,tornados may also structure this ecotone by increasing tree persistence through resprouting。

关键词： eastern deciduous forest landscape patches O-ring analysis post oak tallgrass prairie

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Genotypic diversity of a dominant C_(4) grass across a long-term fire frequency gradient

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Journal of Plant Ecology 2013年第6期6卷 448-458页

作者： Cynthia C.Chang Melinda D.Smith Department of Ecology and Evolutionary Biology Yale UniversityNew HavenCT 06511USA Department of Biology University of WashingtonSeattleWA 98195USA Department of Biology Colorado State UniversityFort CollinsCO 80523USA

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 *** 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 *** addition,we were able to assess the relationships between genetic diversity of ***,species diversity and productivity across this range of fire *** Findings We found no significant relationships between genetic diversity of *** at the local scale(1 m^(2) plot level)and disturbance frequency(burned 2 to 32 times over a 38-year period).However,at the site level(*** all plots sampled within a site,~100 m^(2))there were differences in genotype richness and composition,as well as genomic dissimilarity among individuals of *** richness was greatest for the site burned at an intermediate(4-year)frequency and lowest for the infrequently(20-year)burned *** 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 *** composition of *** 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 *** fire promotes the abundance of dominant grass species,reduces plant community diversity and impacts ecosystem processes such as *** study suggests that

关键词： Andropogon gerardii disturbance frequency genetic relatedness genetic-species diversity relationship genotype richness intermediate disturbance hypothesis productivity tallgrass prairie

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