1
|
Hawkins HJ, Cargill RIM, Van Nuland ME, Hagen SC, Field KJ, Sheldrake M, Soudzilovskaia NA, Kiers ET. Mycorrhizal mycelium as a global carbon pool. Curr Biol 2023; 33:R560-R573. [PMID: 37279689 DOI: 10.1016/j.cub.2023.02.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
For more than 400 million years, mycorrhizal fungi and plants have formed partnerships that are crucial to the emergence and functioning of global ecosystems. The importance of these symbiotic fungi for plant nutrition is well established. However, the role of mycorrhizal fungi in transporting carbon into soil systems on a global scale remains under-explored. This is surprising given that ∼75% of terrestrial carbon is stored belowground and mycorrhizal fungi are stationed at a key entry point of carbon into soil food webs. Here, we analyze nearly 200 datasets to provide the first global quantitative estimates of carbon allocation from plants to the mycelium of mycorrhizal fungi. We estimate that global plant communities allocate 3.93 Gt CO2e per year to arbuscular mycorrhizal fungi, 9.07 Gt CO2e per year to ectomycorrhizal fungi, and 0.12 Gt CO2e per year to ericoid mycorrhizal fungi. Based on this estimate, 13.12 Gt of CO2e fixed by terrestrial plants is, at least temporarily, allocated to the underground mycelium of mycorrhizal fungi per year, equating to ∼36% of current annual CO2 emissions from fossil fuels. We explore the mechanisms by which mycorrhizal fungi affect soil carbon pools and identify approaches to increase our understanding of global carbon fluxes via plant-fungal pathways. Our estimates, although based on the best available evidence, are imperfect and should be interpreted with caution. Nonetheless, our estimations are conservative, and we argue that this work confirms the significant contribution made by mycorrhizal associations to global carbon dynamics. Our findings should motivate their inclusion both within global climate and carbon cycling models, and within conservation policy and practice.
Collapse
Affiliation(s)
- Heidi-Jayne Hawkins
- Department of Biological Sciences, University of Cape Town, Cape Town 7701, South Africa; Conservation International, Forrest House, Belmont Park, Cape Town 7700, South Africa.
| | - Rachael I M Cargill
- Amsterdam Institute for Life and Environment, Vrije Universiteit, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands; AMOLF, Science Park 102, Amsterdam, The Netherlands
| | - Michael E Van Nuland
- Amsterdam Institute for Life and Environment, Vrije Universiteit, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands; Society for the Protection of Underground Networks, SPUN, 3500 South DuPont Highway, Dover, DE 19901, USA
| | | | - Katie J Field
- Plants, Photosynthesis and Soil, School of Biosciences, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Merlin Sheldrake
- Amsterdam Institute for Life and Environment, Vrije Universiteit, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands; Society for the Protection of Underground Networks, SPUN, 3500 South DuPont Highway, Dover, DE 19901, USA
| | | | - E Toby Kiers
- Amsterdam Institute for Life and Environment, Vrije Universiteit, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands; Society for the Protection of Underground Networks, SPUN, 3500 South DuPont Highway, Dover, DE 19901, USA
| |
Collapse
|
2
|
Tisdale RH, Zentella R, Burkey KO. Impact of elevated ozone on yield and carbon-nitrogen content in soybean cultivar 'Jake'. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 306:110855. [PMID: 33775362 DOI: 10.1016/j.plantsci.2021.110855] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 02/07/2021] [Accepted: 02/14/2021] [Indexed: 06/12/2023]
Abstract
Tropospheric ozone (O3) is a pollutant that leads to significant global yield loss in soybean [Glycine max (L.) Merr.]. To ensure soybean productivity in areas of rising O3, it is important to identify tolerant genotypes. This work describes the response of the high-yielding soybean cultivar 'Jake' to elevated O3 concentrations. 'Jake' was treated with either low O3 [charcoal-filtered (CF) air, 12 h mean: 20 ppb] or with O3-enriched air (12 h mean: 87 ppb) over the course of the entire growing season. In contrast to the absence of O3-induced leaf injury under low O3, elevated O3 caused severe leaf injury and decreased stomatal conductance and photosynthesis. Although elevated O3 reduced total leaf area, leaf number, and plant height at different developmental stages, above-ground and root biomass remained unchanged. Analyzing carbon and nitrogen content, we found that elevated O3 altered allocation of both elements, which ultimately led to a 15 % yield loss by decreasing seed size but not seed number. We concluded that cultivar 'Jake' possesses developmental strength to tolerate chronic O3 conditions, attributes that make it suitable breeding material for the generation of new O3 tolerant lines.
Collapse
Affiliation(s)
- Ripley H Tisdale
- U.S. Department of Agriculture, Agricultural Research Service, Plant Science Research Unit, Raleigh, 27607 NC, USA; Department of Crop and Soil Sciences, North Carolina State University, Raleigh, 27695 NC, USA.
| | - Rodolfo Zentella
- U.S. Department of Agriculture, Agricultural Research Service, Plant Science Research Unit, Raleigh, 27607 NC, USA; Department of Crop and Soil Sciences, North Carolina State University, Raleigh, 27695 NC, USA
| | - Kent O Burkey
- U.S. Department of Agriculture, Agricultural Research Service, Plant Science Research Unit, Raleigh, 27607 NC, USA; Department of Crop and Soil Sciences, North Carolina State University, Raleigh, 27695 NC, USA
| |
Collapse
|
3
|
Kong D, Fridley JD. Does plant biomass partitioning reflect energetic investments in carbon and nutrient foraging? Funct Ecol 2019. [DOI: 10.1111/1365-2435.13392] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Deliang Kong
- Liaoning Key Laboratory for Biological Invasions and Global Change Shenyang Agricultural University Shenyang China
| | | |
Collapse
|
4
|
Epron D, Bahn M, Derrien D, Lattanzi FA, Pumpanen J, Gessler A, Högberg P, Maillard P, Dannoura M, Gérant D, Buchmann N. Pulse-labelling trees to study carbon allocation dynamics: a review of methods, current knowledge and future prospects. TREE PHYSIOLOGY 2012; 32:776-98. [PMID: 22700544 DOI: 10.1093/treephys/tps057] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Pulse-labelling of trees with stable or radioactive carbon (C) isotopes offers the unique opportunity to trace the fate of labelled CO(2) into the tree and its release to the soil and the atmosphere. Thus, pulse-labelling enables the quantification of C partitioning in forests and the assessment of the role of partitioning in tree growth, resource acquisition and C sequestration. However, this is associated with challenges as regards the choice of a tracer, the methods of tracing labelled C in tree and soil compartments and the quantitative analysis of C dynamics. Based on data from 47 studies, the rate of transfer differs between broadleaved and coniferous species and decreases as temperature and soil water content decrease. Labelled C is rapidly transferred belowground-within a few days or less-and this transfer is slowed down by drought. Half-lives of labelled C in phloem sap (transfer pool) and in mature leaves (source organs) are short, while those of sink organs (growing tissues, seasonal storage) are longer. (13)C measurements in respiratory efflux at high temporal resolution provide the best estimate of the mean residence times of C in respiratory substrate pools, and the best basis for compartmental modelling. Seasonal C dynamics and allocation patterns indicate that sink strength variations are important drivers for C fluxes. We propose a conceptual model for temperate and boreal trees, which considers the use of recently assimilated C versus stored C. We recommend best practices for designing and analysing pulse-labelling experiments, and identify several topics which we consider of prime importance for future research on C allocation in trees: (i) whole-tree C source-sink relations, (ii) C allocation to secondary metabolism, (iii) responses to environmental change, (iv) effects of seasonality versus phenology in and across biomes, and (v) carbon-nitrogen interactions. Substantial progress is expected from emerging technologies, but the largest challenge remains to carry out in situ whole-tree labelling experiments on mature trees to improve our understanding of the environmental and physiological controls on C allocation.
Collapse
Affiliation(s)
- Daniel Epron
- Université de Lorraine, UMR 1137, Ecologie et Ecophysiologie Forestières, Faculté des Sciences, F-54500 Vandoeuvre-les-Nancy, France.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Corrêa A, Gurevitch J, Martins-Loução MA, Cruz C. C allocation to the fungus is not a cost to the plant in ectomycorrhizae. OIKOS 2011. [DOI: 10.1111/j.1600-0706.2011.19406.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
6
|
Nikolova PS, Andersen CP, Blaschke H, Matyssek R, Häberle KH. Belowground effects of enhanced tropospheric ozone and drought in a beech/spruce forest (Fagus sylvatica L./Picea abies [L.] Karst). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2010; 158:1071-1078. [PMID: 19682778 DOI: 10.1016/j.envpol.2009.07.036] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Accepted: 07/26/2009] [Indexed: 05/28/2023]
Abstract
The effects of experimentally elevated O(3) on soil respiration rates, standing fine-root biomass, fine-root production and delta(13)C signature of newly produced fine roots were investigated in an adult European beech/Norway spruce forest in Germany during two subsequent years with contrasting rainfall patterns. During humid 2002, soil respiration rate was enhanced under elevated O(3) under beech and spruce, and was related to O(3)-stimulated fine-root production only in beech. During dry 2003, the stimulating effect of O(3) on soil respiration rate vanished under spruce, which was correlated with decreased fine-root production in spruce under drought, irrespective of the O(3) regime. delta(13)C signature of newly formed fine-roots was consistent with the differing g(s) of beech and spruce, and indicated stomatal limitation by O(3) in beech and by drought in spruce. Our study showed that drought can override the stimulating O(3) effects on fine-root dynamics and soil respiration in mature beech and spruce forests.
Collapse
Affiliation(s)
- Petia S Nikolova
- Technische Universität München, Weihenstephan Center of Life and Food Sciences, Freising, Germany.
| | | | | | | | | |
Collapse
|
7
|
Mainiero R, Kazda M, Häberle KH, Nikolova PS, Matyssek R. Fine root dynamics of mature European beech (Fagus sylvatica L.) as influenced by elevated ozone concentrations. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2009; 157:2638-2644. [PMID: 19515468 DOI: 10.1016/j.envpol.2009.05.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Revised: 04/20/2009] [Accepted: 05/03/2009] [Indexed: 05/27/2023]
Abstract
Fine root dynamics (diameter < 1 mm) in mature Fagus sylvatica, with the canopies exposed to ambient or twice-ambient ozone concentrations, were investigated throughout 2004. The focus was on the seasonal timing and extent of fine root dynamics (growth, mortality) in relation to the soil environment (water content, temperature). Under ambient ozone concentrations, a significant relationship was found between fine root turnover and soil environmental changes indicating accelerated fine root turnover under favourable soil conditions. In contrast, under elevated ozone, this relationship vanished as the result of an altered temporal pattern of fine root growth. Fine root survival and turnover rate did not differ significantly between the different ozone regimes, although a delay in current-year fine root shedding was found under the elevated ozone concentrations. The data indicate that increasing tropospheric ozone levels can alter the timing of fine root turnover in mature F. sylvatica but do not affect the turnover rate.
Collapse
Affiliation(s)
- Raphael Mainiero
- Department for Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
| | | | | | | | | |
Collapse
|
8
|
Koch N, Andersen CP, Raidl S, Agerer R, Matyssek R, Grams TE. Temperature-respiration relationships differ in mycorrhizal and non-mycorrhizal root systems of Picea abies (L.) Karst. PLANT BIOLOGY (STUTTGART, GERMANY) 2007; 9:545-9. [PMID: 17301933 DOI: 10.1055/s-2006-955946] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Root respiration has been shown to increase with temperature, but less is known about how this relationship is affected by the fungal partner in mycorrhizal root systems. In order to test respiratory temperature dependence, in particular Q (10) of mycorrhizal and non-mycorrhizal root systems, seedlings of PICEA ABIES (L.) Karst. (Norway spruce) were inoculated with the ectomycorrhizal fungus PILODERMA CROCEUM (Eriksson and Hjortstam, SR430; synonym: PILODERMA FALLAX: [Libert] Stalpers) and planted in soil respiration cuvettes (mycocosms). Temperature dependence of hyphal respiration in sterile cultures was determined and compared with respiration of mycorrhizal roots. Respiration rates of mycorrhizal and non-mycorrhizal root systems as well as sterile cultures were sensitive to temperature. Q (10) of mycorrhizal root systems of 3.0 +/- 0.1 was significantly higher than that of non-mycorrhizal systems (2.5 +/- 0.2). Q (10) of P. CROCEUM in sterile cultures (older than 2 months) was similar to that of mycorrhizal root systems, suggesting that mycorrhizae may have a large influence on the temperature sensitivity of roots in spite of their small biomass. Our results stress the importance of considering mycorrhization when modeling the temperature sensitivity of spruce roots.
Collapse
Affiliation(s)
- N Koch
- Department of Ecology, Ecophysiology of Plants, Technische Universität München, Am Hochanger 13, 85354 Freising, Germany.
| | | | | | | | | | | |
Collapse
|
9
|
Kanerva T, Regina K, Rämö K, Ojanperä K, Manninen S. Fluxes of N2O, CH4 and CO2 in a meadow ecosystem exposed to elevated ozone and carbon dioxide for three years. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2007; 145:818-28. [PMID: 16890333 DOI: 10.1016/j.envpol.2006.03.055] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Revised: 03/27/2006] [Accepted: 03/30/2006] [Indexed: 05/11/2023]
Abstract
Open-top chambers (OTCs) were used to evaluate the effects of moderately elevated O3 (40-50 ppb) and CO2 (+100 ppm) and their combination on N2O, CH4 and CO2 fluxes from ground-planted meadow mesocosms. Bimonthly measurements in 2002-2004 showed that the daily fluxes of N2O, CH4 and CO2 reacted mainly to elevated O3, while the fluxes of CO2 also responded to elevated CO2. However, the fluxes did not show any marked response when elevated O3 and CO2 were combined. N2O and CO2 emissions were best explained by soil water content and air and soil temperatures, and they were not clearly associated with potential nitrification and denitrification. Our results suggest that the increasing O3 and/or CO2 concentrations may affect the N2O, CH4 and CO2 fluxes from the soil, but longer study periods are needed to verify the actual consequences of climate change for greenhouse gas emissions.
Collapse
Affiliation(s)
- Teri Kanerva
- Department of Biological and Environmental Sciences, University of Helsinki, P.O. Box 27, 00014 Helsinki, Finland.
| | | | | | | | | |
Collapse
|
10
|
Ranford J, Reiling K. Ozone induced leaf loss and decreased leaf production of European Holly (Ilex aquifolium L.) over multiple seasons. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2007; 145:355-64. [PMID: 16713048 DOI: 10.1016/j.envpol.2006.02.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Revised: 02/21/2006] [Accepted: 02/25/2006] [Indexed: 05/09/2023]
Abstract
European Holly (Ilex aquifolium L.) was used to study the impact of one short (28 day) ozone fumigation episode on leaf production, leaf loss and stomatal conductance (g(s)), in order to explore potential longer term effects over 3 growing seasons. Young I. aquifolium plants received an episode of either charcoal-filtered air or charcoal-filtered air with 70 nl l(-1) O(3) added for 7 h d(-1) over a 28 day period from June 15th 1996, then placed into ambient environment, Stoke-on-Trent, U.K. Data were collected per leaf cohort over the next three growing seasons. Ozone exposure significantly increased leaf loss and stomatal conductance and reduced leaf production over all subsequent seasons. Impact of the initial ozone stress was still detected in leaves that had no direct experimental ozone exposure. This study has shown the potential of ozone to introduce long-term phenological perturbations into ecosystems by influencing productivity over a number of seasons.
Collapse
Affiliation(s)
- Jonathan Ranford
- Applied Sciences, Faculty of Health and Sciences, Staffordshire University, College Road, Stoke-on-Trent, Staffordshire ST4 2DE, UK.
| | | |
Collapse
|
11
|
Lipp CC, Andersen CP. Role of carbohydrate supply in white and brown root respiration of ponderosa pine. THE NEW PHYTOLOGIST 2003; 160:523-531. [PMID: 33873659 DOI: 10.1046/j.1469-8137.2003.00914.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
• Respiration of intact ponderosa pine (Pinus ponderosa) fine roots (< 2.5 mm) was measured to determine the role of recently fixed carbohydrate in maintaining root metabolism of growing white (WR) and recently suberized brown roots (BR). • The CO2 efflux and O2 uptake of individual roots were followed continuously over 24 h after carbohydrate supply was altered by exposing shoots to light/dark treatments and by root excision. • In situ respiration of individual WR and BR averaged 86.0 ± 2.6 and 21.1 ± 1.5 mol CO2 g-1 h-1 , respectively. Growth respiration was estimated to be approximately two-thirds the rate of WR respiration. Attached WR and BR respiration did not decline significantly over 24 h under continuous light. The WR respiration significantly decreased during a dark period. All roots maintained relatively constant respiration rates for at least 6 h after excision. Respiratory quotient (RQ; CO2 : O2 ) was not different between attached (0.84 ± 0.014) and detached (0.85 ± 0.017) roots. CO2 environment of the cuvette did not influence WR or BR respiration. • The WR appear to be more sensitive to supply of current photosynthate than BR. Shoot light environment needs to be considered when measuring root and soil CO2 efflux.
Collapse
Affiliation(s)
- Cynthia C Lipp
- Dynamac Corporation 200 SW 35th Street, Corvallis, OR 97333 USA
| | - Christian P Andersen
- Western Ecology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, 200 SW 35th Street, Corvallis, OR, 97333 USA
| |
Collapse
|
12
|
Laurence JA, Andersen CP. Ozone and natural systems: understanding exposure, response, and risk. ENVIRONMENT INTERNATIONAL 2003; 29:155-160. [PMID: 12676203 DOI: 10.1016/s0160-4120(02)00158-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Research aimed at understanding the response of plants to ozone has been conducted for over four decades but little of it has addressed intact natural systems. Even so, there is sufficient scientific information at this time to support air quality standards that will protect natural terrestrial ecosystems from ozone. What is unknown is the risk associated with continued exposure of natural systems, including both above- and below-ground components, in combination with other stresses including changing temperature and precipitation, elevated carbon dioxide, pests and pathogens, invasive species, and other activities that may fragment the landscape. Research to support an assessment of the ecological risk associated with ozone as it exists, in a milieu of stresses, must include endpoints beyond those addressed in the past, primarily productivity and species composition. To estimate the risk to society of ozone impacts on natural systems, endpoints such as the integrity of soil food webs, the quantity and quality of water supplied from terrestrial ecosystems, wildlife and recreational values, and the transfer and fate of carbon, nutrients, and water within the systems must be quantified. Not only will this research provide the basis for a sound estimate of risk, but also it will improve our understanding of fundamental ecosystem processes.
Collapse
Affiliation(s)
- John A Laurence
- Boyce Thompson Institute for Plant Research, Cornell University, 14853, Ithaca, NY, USA.
| | | |
Collapse
|
13
|
Andersen CP. Source-sink balance and carbon allocation below ground in plants exposed to ozone. THE NEW PHYTOLOGIST 2003; 157:213-228. [PMID: 33873636 DOI: 10.1046/j.1469-8137.2003.00674.x] [Citation(s) in RCA: 216] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The role of tropospheric ozone in altering plant growth and development has been the subject of thousands of publications over the last several decades. Still, there is limited understanding regarding the possible effects of ozone on soil processes. In this review, the effects of ozone are discussed using the flow of carbon from the atmosphere, through the plant to soils, and back to the atmosphere as a framework. A conceptual model based on carbohydrate signaling is used to illustrate physiological changes in response to ozone, and to discuss possible feedbacks that may occur. Despite past emphasis on above-ground effects, ozone has the potential to alter below-ground processes and hence ecosystem characteristics in ways that are not currently being considered. Contents Summary 213 I. Introduction 213 II. Source-sink model: carbohydrate signaling 214 III. Effect of ozone on above-ground sources and sinks 216 IV. Decreased allocation below ground 218 V. Carbon flux to soils 220 VI. Soil food web 223 VII. Summary, conclusions and future research 223 Acknowledgements 223 References 223.
Collapse
Affiliation(s)
- Christian P Andersen
- Western Ecology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, 200 SW 35th St, Corvallis, Oregon 97333, USA
| |
Collapse
|
14
|
|
15
|
Kytöviita MM, Le Thiec D, Dizengremel P. Elevated CO2 and ozone reduce nitrogen acquisition by Pinus halepensis from its mycorrhizal symbiont. PHYSIOLOGIA PLANTARUM 2001; 111:305-312. [PMID: 11240914 DOI: 10.1034/j.1399-3054.2001.1110307.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The effects of 700 µmol mol-1 CO2 and 200 nmol mol-1 ozone on photosynthesis in Pinus halepensis seedlings and on N translocation from its mycorrhizal symbiont, Paxillus involutus, were studied under nutrient-poor conditions. After 79 days of exposure, ozone reduced and elevated CO2 increased net assimilation rate. However, the effect was dependent on daily accumulated exposure. No statistically significant differences in total plant mass accumulation were observed, although ozone-treated plants tended to be smaller. Changes in atmospheric gas concentrations induced changes in allocation of resources: under elevated ozone, shoots showed high priority over roots and had significantly elevated N concentrations. As a result of different shoot N concentration and net carbon assimilation rates, photosynthetic N use efficiency was significantly increased under elevated CO2 and decreased under ozone. The differences in photosynthesis were mirrored in the growth of the fungus in symbiosis with the pine seedlings. However, exposure to CO2 and ozone both reduced the symbiosis-mediated N uptake. The results suggest an increased carbon cost of symbiosis-mediated N uptake under elevated CO2, while under ozone, plant N acquisition is preferentially shifted towards increased root uptake.
Collapse
Affiliation(s)
- Minna-Maarit Kytöviita
- Department of Biology, Oulu University, PL 3000, FIN-90401 Oulu, Finland; Laboratoire de Biologie Forestière, Associé INRA, Université Henri Poincaré-Nancy I, BP 239, F-54506 Vandoeuvre-lès-Nancy, France; INRA-Centre de Recherches Forestières, Unité Ecophysiologie Forestière-Laboratoire de Pollution Atmosphérique, F-54280 Champenoux, France
| | | | | |
Collapse
|
16
|
Olszyk DM, Johnson MG, Phillips DL, Seidler RJ, Tingey DT, Watrud LS. Interactive effects of CO2 and O3 on a ponderosa pine plant/litter/soil mesocosm. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2001; 115:447-462. [PMID: 11789925 DOI: 10.1016/s0269-7491(01)00234-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
To study individual and combined impacts of two important atmospheric trace gases, CO2 and O3, on C and N cycling in forest ecosystems; a multi-year experiment using a small-scale ponderosa pine (Pinus ponderosa Laws.) seedling/soil/litter system was initiated in April 1998. The experiment was conducted in outdoor, sun-lit chambers where aboveground and belowground ecological processes could be studied in detail. This paper describes the approach and methodology used, and presents preliminary data for the first two growing seasons. CO2 treatments were ambient and elevated (ambient + 280 ppm). O3 treatments were elevated (hourly averages to 159 ppb, cumulative exposure > 60 ppb O3, SUM 06 approximately 10.37 ppm h), and a low control level (nearly all hourly averages <40 ppb. SUM 06 approximately 0.07 ppm h). Significant (P < 0.05) individual and interactive effects occurred with elevated CO2 and elevated O3. Elevated CO2 increased needle-level net photosynthetic rates over both seasons. Following the first season, the highest photosynthetic rates were for trees which had previously received elevated O3 in addition to elevated CO2. Elevated CO2 increased seedling stem diameters, with the greatest increase at low O3. Elevated CO2 decreased current year needle % N in the summer. For 1-year-old needles measured in the fall there was a decrease in % N with elevated CO2 at low O3, but an increase in % N with elevated CO2 at elevated O3. Nitrogen fixation (measured by acetylene reduction) was low in ponderosa pine litter and there were no significant CO2 or O3 effects. Neither elevated CO2 nor elevated O3 affected standing root biomass or root length density. Elevated O3 decreased the % N in coarse-fine (1-2 mm diameter) but not in fine (< 1 mm diameter) roots. Both elevated CO2 and elevated O3 tended to increase the number of fungal colony forming units (CFUs) in the AC soil horizon, and elevated O3 tended to decrease bacterial CFUs in the C soil horizon. Thus, after two growing seasons we showed interactive effects of O3 and CO2 in combination, in addition to responses to CO2 or O3 alone for a ponderosa pine plant/litter/soil system.
Collapse
Affiliation(s)
- D M Olszyk
- US Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Corvallis, OR 97333, USA.
| | | | | | | | | | | |
Collapse
|
17
|
McCrady JK, Andersen CP. The effect of ozone on below-ground carbon allocation in wheat. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2000; 107:465-472. [PMID: 15092992 DOI: 10.1016/s0269-7491(99)00122-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/1998] [Accepted: 05/13/1999] [Indexed: 05/24/2023]
Abstract
Short-term (14)CO(2) pulse and chase experiments were conducted in order to investigate the effect of ozone on below-ground carbon allocation in spring wheat seedlings (Triticum aestivum L. 'ANZA'). Wheat seedlings were grown in a sand-hydroponic system and exposed to either high ozone (38-40 ppm-h) or low ozone (23-31 ppm-h) for 21 days in a series of replicated experiments. Following the ozone exposures, the plants were pulsed with (14)CO(2) and allocation of (14)C-labeled photosynthate was measured in the plant and growth media. Soluble root exudates were measured, without disturbing the plant roots, 24 h after the (14)CO(2) pulse. Shoot biomass was reduced by 17% for the high ozone and 9% for the low ozone exposures, relative to control treatments. Root biomass was reduced by 9% for the high ozone exposures, but was not significantly different than the controls for the low ozone. The amount of (14)C activity in the shoot and root tissue 24 h after the (14)CO(2) pulse, normalized to tissue weight, total (14)CO(2) uptake, or the total (14)C retention in each plant, was not affected by either high or low ozone exposures. The amount of (14)C activity measured in the growth media solution surrounding the roots increased 9% for the high ozone exposures, and after normalizing to root size or root (14)C activity, the growth media solution (14)C activity increased 29 and 40%, respectively. Total respiration of (14)CO(2) from the ozone-treated plants decreased, but the decrease was not statistically significant. Our results suggest that soluble root exudation of (14)C activity to the surrounding rhizosphere increases in response to ozone. Increased root exudation to the rhizosphere in response to ozone is contrary to reports of decreased carbon allocation below ground and suggests that rhizosphere microbial activity may be initially stimulated by plant exposure to ozone.
Collapse
Affiliation(s)
- J K McCrady
- US EPA Environmental Research Laboratory, 200 SW 35th Street, Corvallis, OR 97333, USA.
| | | |
Collapse
|
18
|
Cairney JW, Meharg AA. Influences of anthropogenic pollution on mycorrhizal fungal communities. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 1999; 106:169-182. [PMID: 15093044 DOI: 10.1016/s0269-7491(99)00081-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/1998] [Accepted: 03/18/1999] [Indexed: 05/24/2023]
Abstract
Mycorrhizal fungi form complex communities in the root systems of most plant species and are thought to be important in terrestrial ecosystem sustainability. We have reviewed the literature relating to the influence of the major forms of anthropogenic pollution on the structure and dynamics of mycorrhizal fungal communities. All forms of pollution have been reported to alter the structure of below-ground communities of mycorrhizal fungi to some degree, although the extent to which such changes will be sustained in the longer term is at present not clear. The major limitation to predicting the consequences of pollution-mediated changes in mycorrhizal fungal communities to terrestrial habitats is our limited understanding of the functional significance of mycorrhizal fungal diversity. While this is identified as a priority area for future research, it is suggested that, in the absence of such data, an understanding of pollution-mediated changes in mycorrhizal mycelial systems in soil may provide useful indicators for sustainability of mycorrhizal systems.
Collapse
Affiliation(s)
- J W Cairney
- Mycorrhiza Research Group, School of Science, University of Western Sydney (Nepean), PO Box 10, Kingswood, NSW 2747, Australia.
| | | |
Collapse
|
19
|
Andersen CP, Rygiewicz PT. Understanding plant-soil relationships using controlled environment facilities. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1999; 24:309-318. [PMID: 11542539 DOI: 10.1016/s0273-1177(99)00484-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Although soil is a component of terrestrial ecosystems, it is comprised of a complex web of interacting organisms, and therefore can be considered itself as an ecosystem. Soil microflora and fauna derive energy from plants and plant residues and serve important functions in maintaining soil physical and chemical properties, thereby affecting net primary productivity (NPP), and in the case of contained environments, the quality of the life support system. We have been using 3 controlled-environment facilities (CEF's) that incorporate different levels of soil biological complexity and environmental control, and differ in their resemblance to natural ecosystems, to study relationships among plant physiology, soil ecology, fluxes of minerals and nutrients, and overall ecosystem function. The simplest system utilizes growth chambers and specialized root chambers with organic-less media to study the physiology of plant-mycorrhizal associations. A second system incorporates natural soil in open-top chambers to study soil bacterial and fungal population response to stress. The most complex CEF incorporates reconstructed soil profiles in a "constructed" ecosystem, enabling close examination of the soil foodweb. Our results show that closed ecosystem research is important for understanding mechanisms of response to ecosystem stresses. In addition, responses observed at one level of biological complexity may not allow prediction of response at a different level of biological complexity. In closed life support systems, incorporating soil foodwebs will require less artificial manipulation to maintain system stability and sustainability.
Collapse
Affiliation(s)
- C P Andersen
- USEPA National Health and Environmental Effects Research Laboratory, Western Ecology Division, Corvallis, OR 97333, USA.
| | | |
Collapse
|
20
|
Scagel CF, Andersen CP. Seasonal changes in root and soil respiration of ozone-exposed ponderosa pine (Pinus ponderosa) grown in different substrates. THE NEW PHYTOLOGIST 1997; 136:627-643. [PMID: 33863111 DOI: 10.1046/j.1469-8137.1997.00779.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Exposure to ozone (O3 ) has been shown to decrease the allocation of carbon to tree roots. Decreased allocation of carbon to roots might disrupt root metabolism and rhizosphere organisms. The effects of soil type and shoot O3 exposure on below-ground respiration and soil microbial populations were investigated using container-grown ponderosa pine (Pinus ponderosa Laws.) growing in a low-nutrient soil, or a fertilizer-amended organic potting media, and exposed to one of three levels of O3 for two growing seasons in open-top exposure chambers. A closed system, designed to measure below-ground respiratory activity (CO2 production, O2 consumption and RQ-Respiration Quotient; (CO2 :02 ) of plants growing in pots, was used monthly to monitor below-ground respiration of 3-yr-old ponderosa pine. Although seasonal differences were detected, CO2 production (μmol h-1 g-1 total root d. wt), O2 consumption (μmol h-1 g-1 total root d. wt) and RQ (CO2 :O2 ) increased with increasing O3 exposure level. Seasonal patterns showed increased respiration rates during periods of rapid root growth in spring and early fall. Respiration quotient tended to decrease during known periods of active root growth in control seedlings, but a similar response was not observed in O3 -treated seedlings. Responses to O3 were greatest in the soil-grown plants, which had a lower fertility level than media-grown plants. Although root d. wt was decreased, root: shoot ratios did not change in response to O3 . Soil-grown plants had higher root-shoot ratios than media-grown plants, reflecting the lower fertility of the soil. Plant exposure to O3 was found to affect both active and total populations of soil organisms. In both organic potting media and in soil, biomass of active soil fungi, and the ratio of active-fungal to active-bacterial biomass increased with increasing plant exposure to O3 . The effect of O3 on total fungal and bacterial biomass was not linear: at low O3 levels, total fungal and bacterial biomass increased; at the high O3 level, total fungal and bacterial biomass decreased compared with those of controls. Our results show that O3 exposure to shoots significantly disrupts CO2 production and O2 consumption of soil and roots of ponderosa pine seedlings. Below-ground respiratory differences were thought to be a result of changes in respiratory substrates, carbon refixation within the plant and soil microbial activity. Ozone also changes below-ground RQ, suggesting that O3 substantially disrupts root metabolism and interactions with rhizosphere organisms. Ozone exposure of ponderosa pine grown in different soil types can disrupt below-ground respiration and influence populations of soil organisms without alteration of biomass partitioning between above- and below-ground plant components. Collectively, the effect of O3 on the below-ground system is of concern since it is likely that these changes are accompanied by a change in the ability of root systems to acquire nutrient and water resources and possibly to synthesize amino acids and proteins necessary for normal plant function.
Collapse
Affiliation(s)
- C F Scagel
- Man Tech Environmental Research Services Corporation, 200 S.W. 35th Street, Corvallis, OR, USA
| | - C P Andersen
- U.S.E.P.A. National Health and Environmental Effects Research Laboratory, Western Ecology Division, 200 S.W. 35th Street, Corvallis, OR 97333, USA
| |
Collapse
|