351
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Tingey DT, Lee EH, Waschmann R, Johnson MG, Rygiewicz PT. Does soil CO2 efflux acclimatize to elevated temperature and CO2 during long-term treatment of Douglas-fir seedlings? THE NEW PHYTOLOGIST 2006; 170:107-18. [PMID: 16539608 DOI: 10.1111/j.1469-8137.2006.01646.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We investigated the effects of elevated soil temperature and atmospheric CO2 on soil CO2 efflux (SCE) during the third and fourth years of study. We hypothesized that elevated temperature would stimulate SCE, and elevated CO2 would also stimulate SCE with the stimulation being greater at higher temperatures. The study was conducted in sun-lit controlled-environment chambers using Douglas-fir (Pseudotsuga menziesii) seedlings grown in reconstructed litter-soil systems. We used a randomized design with two soil temperature and two atmospheric CO2 treatments. The SCE was measured every 4 wk for 18 months. Neither elevated temperature nor CO2 stimulated SCE. Elevated CO2 increased the temperature sensitivity of SCE. During the winter, the relationship between SCE and soil moisture was negative but it was positive during the summer. The seasonal patterns in SCE were associated with seasonal changes in photosynthesis and above-ground plant growth. SCE acclimatized in the high-temperature treatment, probably because of a loss of labile soil carbon. Elevated CO2 treatment increased the temperature sensitivity of SCE, probably through an increase in substrate availability.
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Affiliation(s)
- D T Tingey
- US Environmental Protection Agency, Western Ecology Division, 200 SW 35th Street, Corvallis, OR 97333, USA
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352
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Atkin OK, Bruhn D, Hurry VM, Tjoelker MG. The hot and the cold: unravelling the variable response of plant respiration to temperature. FUNCTIONAL PLANT BIOLOGY : FPB 2005; 32:87-105. [PMID: 32689114 DOI: 10.1071/fp03176] [Citation(s) in RCA: 220] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2003] [Accepted: 12/14/2004] [Indexed: 05/28/2023]
Abstract
When predicting the effects of climate change, global carbon circulation models that include a positive feedback effect of climate warming on the carbon cycle often assume that (1) plant respiration increases exponentially with temperature (with a constant Q10) and (2) that there is no acclimation of respiration to long-term changes in temperature. In this review, we show that these two assumptions are incorrect. While Q10 does not respond systematically to elevated atmospheric CO2 concentrations, other factors such as temperature, light, and water availability all have the potential to influence the temperature sensitivity of respiratory CO2 efflux. Roots and leaves can also differ in their Q10 values, as can upper and lower canopy leaves. The consequences of such variable Q10 values need to be fully explored in carbon modelling. Here, we consider the extent of variability in the degree of thermal acclimation of respiration, and discuss in detail the biochemical mechanisms underpinning this variability; the response of respiration to long-term changes in temperature is highly dependent on the effect of temperature on plant development, and on interactive effects of temperature and other abiotic factors (e.g. irradiance, drought and nutrient availability). Rather than acclimating to the daily mean temperature, recent studies suggest that other components of the daily temperature regime can be important (e.g. daily minimum and / or night temperature). In some cases, acclimation may simply reflect a passive response to changes in respiratory substrate availability, whereas in others acclimation may be critical in helping plants grow and survive at contrasting temperatures. We also consider the impact of acclimation on the balance between respiration and photosynthesis; although environmental factors such as water availability can alter the balance between these two processes, the available data suggests that temperature-mediated differences in dark leaf respiration are closely linked to concomitant differences in leaf photosynthesis. We conclude by highlighting the need for a greater process-based understanding of thermal acclimation of respiration if we are to successfully predict future ecosystem CO2 fluxes and potential feedbacks on atmospheric CO2 concentrations.
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Affiliation(s)
- Owen K Atkin
- Department of Biology (Area 2), The University of York, PO Box 373, York YO10 5YW, UK. Corresponding author. Email
| | - Dan Bruhn
- Cooperative Research Centre for Green House Accounting, Ecosystem Dynamics Group, Research School of Biological Sciences, Australian National University, Canberra, ACT 0200, Australia
| | - Vaughan M Hurry
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, 901 87 Umeå, Sweden
| | - Mark G Tjoelker
- Department of Forest Science, Texas A & M University, 2135 TAMU, College Station, TX 77843-2135, USA
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353
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354
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Dong Y, Qi Y, Liu J, Geng Y, Manfred D, Yang X, Liu L. Variation characteristics of soil respiration fluxes in four types of grassland communities under different precipitation intensity. ACTA ACUST UNITED AC 2005. [DOI: 10.1007/bf02897484] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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355
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356
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Biasi C, Rusalimova O, Meyer H, Kaiser C, Wanek W, Barsukov P, Junger H, Richter A. Temperature-dependent shift from labile to recalcitrant carbon sources of arctic heterotrophs. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2005; 19:1401-8. [PMID: 15880633 DOI: 10.1002/rcm.1911] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Soils of high latitudes store approximately one-third of the global soil carbon pool. Decomposition of soil organic matter (SOM) is expected to increase in response to global warming, which is most pronounced in northern latitudes. It is, however, unclear if microorganisms are able to utilize more stable, recalcitrant C pools, when labile soil carbon pools will be depleted due to increasing temperatures. Here we report on an incubation experiment with intact soil cores of a frost-boil tundra ecosystem at three different temperatures (2 degrees C, 12 degrees C and 24 degrees C). In order to assess which fractions of the SOM are available for decomposition at various temperatures, we analyzed the isotopic signature of respired CO2 and of different SOM fractions. The delta13C values of CO2 respired were negatively correlated with temperature, indicating the utilization of SOM fractions that were depleted in 13C at higher temperatures. Chemical fractionation of SOM showed that the water-soluble fraction (presumably the most easily available substrates for microbial respiration) was most enriched in 13C, while the acid-insoluble pool (recalcitrant substrates) was most depleted in 13C. Our results therefore suggest that, at higher temperatures, recalcitrant compounds are preferentially respired by arctic microbes. When the isotopic signatures of respired CO2 of soils which had been incubated at 24 degrees C were measured at 12 degrees C, the delta13C values shifted to values found in soils incubated at 12 degrees C, indicating the reversible use of more easily available substrates. Analysis of phospholipid fatty acid profiles showed significant differences in microbial community structure at various incubation temperatures indicating that microorganisms with preference for more recalcitrant compounds establish as temperatures increase. In summary our results demonstrate that a large portion of tundra SOM is potentially mineralizable.
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Affiliation(s)
- Christina Biasi
- Institute of Ecology and Conservation Biology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
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357
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Knorr W, Prentice IC, House JI, Holland EA. Long-term sensitivity of soil carbon turnover to warming. Nature 2005; 433:298-301. [PMID: 15662420 DOI: 10.1038/nature03226] [Citation(s) in RCA: 280] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2004] [Accepted: 11/24/2004] [Indexed: 11/08/2022]
Abstract
The sensitivity of soil carbon to warming is a major uncertainty in projections of carbon dioxide concentration and climate. Experimental studies overwhelmingly indicate increased soil organic carbon (SOC) decomposition at higher temperatures, resulting in increased carbon dioxide emissions from soils. However, recent findings have been cited as evidence against increased soil carbon emissions in a warmer world. In soil warming experiments, the initially increased carbon dioxide efflux returns to pre-warming rates within one to three years, and apparent carbon pool turnover times are insensitive to temperature. It has already been suggested that the apparent lack of temperature dependence could be an artefact due to neglecting the extreme heterogeneity of soil carbon, but no explicit model has yet been presented that can reconcile all the above findings. Here we present a simple three-pool model that partitions SOC into components with different intrinsic turnover rates. Using this model, we show that the results of all the soil-warming experiments are compatible with long-term temperature sensitivity of SOC turnover: they can be explained by rapid depletion of labile SOC combined with the negligible response of non-labile SOC on experimental timescales. Furthermore, we present evidence that non-labile SOC is more sensitive to temperature than labile SOC, implying that the long-term positive feedback of soil decomposition in a warming world may be even stronger than predicted by global models.
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Affiliation(s)
- W Knorr
- Max Planck Institute for Biogeochemistry, PO Box 100164, D-07701 Jena, Germany.
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358
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Hashimoto H, Nemani RR, White MA, Jolly WM, Piper SC, Keeling CD, Myneni RB, Running SW. El Niño-Southern Oscillation-induced variability in terrestrial carbon cycling. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2004jd004959] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Hirofumi Hashimoto
- Graduate School of Agricultural and Life Sciences; University of Tokyo; Tokyo Japan
| | | | - Michael A. White
- Department of Aquatic, Watershed, and Earth Resources; Utah State University; Logan Utah USA
| | - William M. Jolly
- Numerical Terradynamic Simulation Group (NTSG), School of Forestry; University of Montana; Missoula Montana USA
| | - Steve C. Piper
- Scripps Institution of Oceanography; La Jolla California USA
| | | | - Ranga B. Myneni
- Department of Geography; Boston University; Boston Massachusetts USA
| | - Steven W. Running
- Numerical Terradynamic Simulation Group (NTSG), School of Forestry; University of Montana; Missoula Montana USA
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359
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Smith DL, Johnson L. VEGETATION-MEDIATED CHANGES IN MICROCLIMATE REDUCE SOIL RESPIRATION AS WOODLANDS EXPAND INTO GRASSLANDS. Ecology 2004. [DOI: 10.1890/03-0576] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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360
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Ekblad A, Boström B, Holm A, Comstedt D. Forest soil respiration rate and ?13C is regulated by recent above ground weather conditions. Oecologia 2004; 143:136-42. [PMID: 15578226 DOI: 10.1007/s00442-004-1776-z] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2004] [Accepted: 11/06/2004] [Indexed: 11/27/2022]
Abstract
Soil respiration, a key component of the global carbon cycle, is a major source of uncertainty when estimating terrestrial carbon budgets at ecosystem and higher levels. Rates of soil and root respiration are assumed to be dependent on soil temperature and soil moisture yet these factors often barely explain half the seasonal variation in soil respiration. We here found that soil moisture (range 16.5-27.6% of dry weight) and soil temperature (range 8-17.5 degrees C) together explained 55% of the variance (cross-validated explained variance; Q2) in soil respiration rate (range 1.0-3.4 micromol C m(-2) s(-1)) in a Norway spruce (Picea abies) forest. We hypothesised that this was due to that the two components of soil respiration, root respiration and decomposition, are governed by different factors. We therefore applied PLS (partial least squares regression) multivariate modelling in which we, together with below ground temperature and soil moisture, used the recent above ground air temperature and air humidity (vapour pressure deficit, VPD) conditions as x-variables. We found that air temperature and VPD data collected 1-4 days before respiration measurements explained 86% of the seasonal variation in the rate of soil respiration. The addition of soil moisture and soil temperature to the PLS-models increased the Q2 to 93%. delta13C analysis of soil respiration supported the hypotheses that there was a fast flux of photosynthates to root respiration and a dependence on recent above ground weather conditions. Taken together, our results suggest that shoot activities the preceding 1-6 days influence, to a large degree, the rate of root and soil respiration. We propose this above ground influence on soil respiration to be proportionally largest in the middle of the growing season and in situations when there is large day-to-day shifts in the above ground weather conditions. During such conditions soil temperature may not exert the major control on root respiration.
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Affiliation(s)
- Alf Ekblad
- Department of Natural Sciences, Orebro University, 701 82 Orebro, Sweden.
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361
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Klein JA, Harte J, Zhao XQ. Experimental warming causes large and rapid species loss, dampened by simulated grazing, on the Tibetan Plateau. Ecol Lett 2004. [DOI: 10.1111/j.1461-0248.2004.00677.x] [Citation(s) in RCA: 383] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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362
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He J, Wang Z, Fang J. Issues and prospects of belowground ecology with special reference to global climate change. ACTA ACUST UNITED AC 2004. [DOI: 10.1007/bf03184277] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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363
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Lange OL, Green TGA. Lichens show that fungi can acclimate their respiration to seasonal changes in temperature. Oecologia 2004; 142:11-9. [PMID: 15322904 DOI: 10.1007/s00442-004-1697-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2004] [Accepted: 07/21/2004] [Indexed: 10/26/2022]
Abstract
Five species of lichens, the majority members of a soil-crust community ( Cladonia convoluta, Diploschistes muscorum, Fulgensia fulgens, Lecanora muralis, Squamarina lentigera) showed seasonal changes of temperature sensitivity of their dark respiration (DR) to such an extent that several substantially met the definition of full acclimation, i.e. near identical DR under different nocturnal temperature conditions during the course of the year. C. convoluta, for example, had maximal DR at 5 degrees C of -0.42, -1.11 and -0.09 nmol CO(2) g(-1) s(-1) in autumn, winter, and summer, respectively, a tenfold range. However, at the mean night temperatures for the same three seasons, 9.7 degrees C, 4.2 degrees C and 13.6 degrees C, maximal DR were almost identical at -1.11, -0.93, and -1.45 nmol CO(2) g(-1) s(-1). The information was extracted from measurements using automatic cuvettes that continuously recorded a sample lichen's gas exchange every 30 min under near-natural conditions. The longest period (for L. muralis) covered 15 months and 22,000 data sets whilst, for the other species studied, data blocks were available throughout the calendar year. The acclimation of DR means that maximal net carbon fixation rates remain substantially similar throughout the year and are not depressed by increased carbon loss by respiration in warmer seasons. This is especially important for lichens because of their normally high rate of DR compared to net photosynthesis. We suggest that lichens, especially soil-crust species, could be a suitable model for fungi generally, a group of organisms for which little is known about temperature acclimation because of the great difficulty in separating the organism from its growth medium. Fungi, whether saprophytic, symbiotic or parasitic, including soil lichens, are important components of soil ecosystems and contribute much of the respired CO(2) from these systems. Temperature acclimation by fungi would mean that expected increases in carbon losses caused by global climate warming from soil ecosystems might not be as extensive as first thought. This would ameliorate this positive feedback loop present in some climate models and might substantially lower the predicted warming.
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Affiliation(s)
- Otto L Lange
- Julius-von-Sachs-Institut für Biowissenschaften der Universität Würzburg, Lehrstuhl für Botanik II, Julius-von-Sachs-Platz 3, 97084 Würzburg, Germany.
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364
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Dunne JA, Saleska SR, Fischer ML, Harte J. INTEGRATING EXPERIMENTAL AND GRADIENT METHODS IN ECOLOGICAL CLIMATE CHANGE RESEARCH. Ecology 2004. [DOI: 10.1890/03-8003] [Citation(s) in RCA: 203] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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365
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Biosphere dynamics: Challenges for Earth system models. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/150gm21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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366
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Euskirchen ES, Chen J, Gustafson EJ, Ma S. Soil Respiration at Dominant Patch Types within a Managed Northern Wisconsin Landscape. Ecosystems 2003. [DOI: 10.1007/pl00021505] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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367
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Atkin OK, Tjoelker MG. Thermal acclimation and the dynamic response of plant respiration to temperature. TRENDS IN PLANT SCIENCE 2003; 8:343-51. [PMID: 12878019 DOI: 10.1016/s1360-1385(03)00136-5] [Citation(s) in RCA: 538] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Temperature-mediated changes in plant respiration (R) are now accepted as an important component of the biosphere's response to global climate change. Here we discuss the underlying mechanisms responsible for the dynamic response of plant respiration to short and long-term temperature changes. The Q(10) is often assumed to be 2.0 (i.e. R doubles per 10 degrees C rise in temperature); however, the Q(10) is not constant (e.g. it declines near-linearly with increasing temperature). The temperature dependence of Q(10) is linked to shifts in the control exerted by maximum enzyme activity at low temperature and substrate limitations at high temperature. In the long term, acclimation of R to temperature is common, in effect reducing the temperature sensitivity of R to changes in thermal environment, with the temperature during plant development setting the maximal thermal acclimation of R.
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Affiliation(s)
- Owen K Atkin
- Department of Biology, The University of York, PO Box 373, York YO10 5YW, UK.
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368
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Enquist BJ, Economo EP, Huxman TE, Allen AP, Ignace DD, Gillooly JF. Scaling metabolism from organisms to ecosystems. Nature 2003; 423:639-42. [PMID: 12789338 DOI: 10.1038/nature01671] [Citation(s) in RCA: 315] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2002] [Accepted: 03/20/2003] [Indexed: 11/08/2022]
Abstract
Understanding energy and material fluxes through ecosystems is central to many questions in global change biology and ecology. Ecosystem respiration is a critical component of the carbon cycle and might be important in regulating biosphere response to global climate change. Here we derive a general model of ecosystem respiration based on the kinetics of metabolic reactions and the scaling of resource use by individual organisms. The model predicts that fluxes of CO2 and energy are invariant of ecosystem biomass, but are strongly influenced by temperature, variation in cellular metabolism and rates of supply of limiting resources (water and/or nutrients). Variation in ecosystem respiration within sites, as calculated from a network of CO2 flux towers, provides robust support for the model's predictions. However, data indicate that variation in annual flux between sites is not strongly dependent on average site temperature or latitude. This presents an interesting paradox with regard to the expected temperature dependence. Nevertheless, our model provides a basis for quantitatively understanding energy and material flux between the atmosphere and biosphere.
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Affiliation(s)
- Brian J Enquist
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA.
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369
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Staddon PL, Ramsey CB, Ostle N, Ineson P, Fitter AH. Rapid turnover of hyphae of mycorrhizal fungi determined by AMS microanalysis of 14C. Science 2003; 300:1138-40. [PMID: 12750519 DOI: 10.1126/science.1084269] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Processes in the soil remain among the least well-characterized components of the carbon cycle. Arbuscular mycorrhizal (AM) fungi are ubiquitous root symbionts in many terrestrial ecosystems and account for a large fraction of photosynthate in a wide range of ecosystems; they therefore play a key role in the terrestrial carbon cycle. A large part of the fungal mycelium is outside the root (the extraradical mycelium, ERM) and, because of the dispersed growth pattern and the small diameter of the hyphae (<5 micrometers), exceptionally difficult to study quantitatively. Critically, the longevity of these fine hyphae has never been measured, although it is assumed to be short. To quantify carbon turnover in these hyphae, we exposed mycorrhizal plants to fossil ("carbon-14-dead") carbon dioxide and collected samples of ERM hyphae (up to 116 micrograms) over the following 29 days. Analyses of their carbon-14 content by accelerator mass spectrometry (AMS) showed that most ERM hyphae of AM fungi live, on average, 5 to 6 days. This high turnover rate reveals a large and rapid mycorrhizal pathway of carbon in the soil carbon cycle.
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Affiliation(s)
- Philip L Staddon
- Department of Biology, University of York, Post Office Box 373, York YO10 5YW, UK.
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370
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Knapp AK, Fay PA, Blair JM, Collins SL, Smith MD, Carlisle JD, Harper CW, Danner BT, Lett MS, McCarron JK. Rainfall variability, carbon cycling, and plant species diversity in a mesic grassland. Science 2002; 298:2202-5. [PMID: 12481139 DOI: 10.1126/science.1076347] [Citation(s) in RCA: 395] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Ecosystem responses to increased variability in rainfall, a prediction of general circulation models, were assessed in native grassland by reducing storm frequency and increasing rainfall quantity per storm during a 4-year experiment. More extreme rainfall patterns, without concurrent changes in total rainfall quantity, increased temporal variability in soil moisture and plant species diversity. However, carbon cycling processes such as soil CO2 flux, CO2 uptake by the dominant grasses, and aboveground net primary productivity (ANPP) were reduced, and ANPP was more responsive to soil moisture variability than to mean soil water content. Our results show that projected increases in rainfall variability can rapidly alter key carbon cycling processes and plant community composition, independent of changes in total precipitation.
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Affiliation(s)
- Alan K Knapp
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA.
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371
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Melillo JM, Steudler PA, Aber JD, Newkirk K, Lux H, Bowles FP, Catricala C, Magill A, Ahrens T, Morrisseau S. Soil warming and carbon-cycle feedbacks to the climate system. Science 2002; 298:2173-6. [PMID: 12481133 DOI: 10.1126/science.1074153] [Citation(s) in RCA: 426] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In a decade-long soil warming experiment in a mid-latitude hardwood forest, we documented changes in soil carbon and nitrogen cycling in order to investigate the consequences of these changes for the climate system. Here we show that whereas soil warming accelerates soil organic matter decay and carbon dioxide fluxes to the atmosphere, this response is small and short-lived for a mid-latitude forest, because of the limited size of the labile soil carbon pool. We also show that warming increases the availability of mineral nitrogen to plants. Because plant growth in many mid-latitude forests is nitrogen-limited, warming has the potential to indirectly stimulate enough carbon storage in plants to at least compensate for the carbon losses from soils. Our results challenge assumptions made in some climate models that lead to projections of large long-term releases of soil carbon in response to warming of forest ecosystems.
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Affiliation(s)
- J M Melillo
- The Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
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372
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Wan S, Yuan T, Bowdish S, Wallace L, Russell SD, Luo Y. Response of an allergenic species, Ambrosia psilostachya (Asteraceae), to experimental warming and clipping: implications for public health. AMERICAN JOURNAL OF BOTANY 2002; 89:1843-1846. [PMID: 21665612 DOI: 10.3732/ajb.89.11.1843] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We examined the responses of an allergenic species, western ragweed (Ambrosia psilostachya DC.), to experimental warming and clipping. The experiment was conducted in a tallgrass prairie in Oklahoma, USA, between 1999 and 2001. Warming increased ragweed stems by 88% when not clipped and 46% when clipped. Clipping increased ragweed stems by 75% and 36% in the control and warmed plots, respectively. In 2001, warming resulted in a 105% increase in ragweed aboveground biomass (AGB), and the ratio of ragweed AGB to total AGB increased by 79%. Dry mass per ragweed stem in the warmed plots was 37% and 38% greater than that in the control plots in 2000 and 2001, respectively. Although warming caused no difference in pollen production per stem, total pollen production increased by 84% (P < 0.05) because there were more ragweed stems. Experimental warming significantly increased pollen diameter from 21.2 μm in the control plots to 23.9 μm in the warmed plots (a 13% increase). The results from our experiment suggest that global warming could aggravate allergic hazards and thereby jeopardize public health.
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Affiliation(s)
- Shiqiang Wan
- Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma 73019-0245 USA
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373
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374
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Pearson H. Little heat on the prairie. Nature 2001. [DOI: 10.1038/news011011-11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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