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1.
Yanghui He Xuhui Zhou Zhen Jia Lingyan Zhou Hongyang Chen Ruiqiang Liu Zhenggang Du Guiyao Zhou Junjiong Shao Junxia Ding Kelong Chen Iain P. Hartley 《Global Change Biology》2023,29(4):1178-1187
Multiple lines of existing evidence suggest that increasing CO2 emission from soils in response to rising temperature could accelerate global warming. However, in experimental studies, the initial positive response of soil heterotrophic respiration (RH) to warming often weakens over time (referred to apparent thermal acclimation). If the decreased RH is driven by thermal adaptation of soil microbial community, the potential for soil carbon (C) losses would be reduced substantially. In the meanwhile, the response could equally be caused by substrate depletion, and would then reflect the gradual loss of soil C. To address uncertainties regarding the causes of apparent thermal acclimation, we carried out sterilization and inoculation experiments using the soil samples from an alpine meadow with 6 years of warming and nitrogen (N) addition. We demonstrate that substrate depletion, rather than microbial adaptation, determined the response of RH to long-term warming. Furthermore, N addition appeared to alleviate the apparent acclimation of RH to warming. Our study provides strong empirical support for substrate availability being the cause of the apparent acclimation of soil microbial respiration to temperature. Thus, these mechanistic insights could facilitate efforts of biogeochemical modeling to accurately project soil C stocks in the future climate. 相似文献
2.
Mark A. Bradford Christian A. Davies Serita D. Frey Thomas R. Maddox Jerry M. Melillo Jacqueline E. Mohan James F. Reynolds Kathleen K. Treseder Matthew D. Wallenstein 《Ecology letters》2008,11(12):1316-1327
In the short‐term heterotrophic soil respiration is strongly and positively related to temperature. In the long‐term, its response to temperature is uncertain. One reason for this is because in field experiments increases in respiration due to warming are relatively short‐lived. The explanations proposed for this ephemeral response include depletion of fast‐cycling, soil carbon pools and thermal adaptation of microbial respiration. Using a > 15 year soil warming experiment in a mid‐latitude forest, we show that the apparent ‘acclimation’ of soil respiration at the ecosystem scale results from combined effects of reductions in soil carbon pools and microbial biomass, and thermal adaptation of microbial respiration. Mass‐specific respiration rates were lower when seasonal temperatures were higher, suggesting that rate reductions under experimental warming likely occurred through temperature‐induced changes in the microbial community. Our results imply that stimulatory effects of global temperature rise on soil respiration rates may be lower than currently predicted. 相似文献
3.
Microbial physiology and soil CO2 efflux after 9 years of soil warming in a temperate forest – no indications for thermal adaptations
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Andreas Schindlbacher Jörg Schnecker Mounir Takriti Werner Borken Wolfgang Wanek 《Global Change Biology》2015,21(11):4265-4277
Thermal adaptations of soil microorganisms could mitigate or facilitate global warming effects on soil organic matter (SOM) decomposition and soil CO2 efflux. We incubated soil from warmed and control subplots of a forest soil warming experiment to assess whether 9 years of soil warming affected the rates and the temperature sensitivity of the soil CO2 efflux, extracellular enzyme activities, microbial efficiency, and gross N mineralization. Mineral soil (0–10 cm depth) was incubated at temperatures ranging from 3 to 23 °C. No adaptations to long‐term warming were observed regarding the heterotrophic soil CO2 efflux (R10 warmed: 2.31 ± 0.15 μmol m?2 s?1, control: 2.34 ± 0.29 μmol m?2 s?1; Q10 warmed: 2.45 ± 0.06, control: 2.45 ± 0.04). Potential enzyme activities increased with incubation temperature, but the temperature sensitivity of the enzymes did not differ between the warmed and the control soils. The ratio of C : N acquiring enzyme activities was significantly higher in the warmed soil. Microbial biomass‐specific respiration rates increased with incubation temperature, but the rates and the temperature sensitivity (Q10 warmed: 2.54 ± 0.23, control 2.75 ± 0.17) did not differ between warmed and control soils. Microbial substrate use efficiency (SUE) declined with increasing incubation temperature in both, warmed and control, soils. SUE and its temperature sensitivity (Q10 warmed: 0.84 ± 0.03, control: 0.88 ± 0.01) did not differ between warmed and control soils either. Gross N mineralization was invariant to incubation temperature and was not affected by long‐term soil warming. Our results indicate that thermal adaptations of the microbial decomposer community are unlikely to occur in C‐rich calcareous temperate forest soils. 相似文献
4.
Yaoming Li Wangwang Lv Lili Jiang Lirong Zhang Shiping Wang Qi Wang Kai Xue Bowen Li Peipei Liu Huan Hong Wangmu Renzen A Wang Caiyun Luo Zhenhua Zhang Tsechoe Dorji Neslihan Ta Zhezhen Wang Huakun Zhou Yanfen Wang 《Global Change Biology》2019,25(10):3438-3449
Changes in labile carbon (LC) pools and microbial communities are the primary factors controlling soil heterotrophic respiration (Rh) in warming experiments. Warming is expected to initially increase Rh but studies show this increase may not be continuous or sustained. Specifically, LC and soil microbiome have been shown to contribute to the effect of extended warming on Rh. However, their relative contribution is unclear and this gap in knowledge causes considerable uncertainty in the prediction of carbon cycle feedbacks to climate change. In this study, we used a two‐step incubation approach to reveal the relative contribution of LC limitation and soil microbial community responses in attenuating the effect that extended warming has on Rh. Soil samples from three Tibetan ecosystems—an alpine meadow (AM), alpine steppe (AS), and desert steppe (DS)—were exposed to a temperature gradient of 5–25°C. After an initial incubation period, soils were processed in one of two methods: (a) soils were sterilized then inoculated with parent soil microbes to assess the LC limitation effects, while controlling for microbial community responses; or (b) soil microbes from the incubations were used to inoculate sterilized parent soils to assess the microbial community effects, while controlling for LC limitation. We found both LC limitation and microbial community responses led to significant declines in Rh by 37% and 30%, respectively, but their relative contributions were ecosystem specific. LC limitation alone caused a greater Rh decrease for DS soils than AMs or ASs. Our study demonstrates that soil carbon loss due to Rh in Tibetan alpine soils—especially in copiotrophic soils—will be weakened by microbial community responses under short‐term warming. 相似文献
5.
Pathways regulating decreased soil respiration with warming in a biocrust‐dominated dryland
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Pablo García‐Palacios Cristina Escolar Marina Dacal Manuel Delgado‐Baquerizo Beatriz Gozalo Victoria Ochoa Fernando T. Maestre 《Global Change Biology》2018,24(10):4645-4656
A positive soil carbon (C)‐climate feedback is embedded into the climatic models of the IPCC. However, recent global syntheses indicate that the temperature sensitivity of soil respiration (RS) in drylands, the largest biome on Earth, is actually lower in warmed than in control plots. Consequently, soil C losses with future warming are expected to be low compared with other biomes. Nevertheless, the empirical basis for these global extrapolations is still poor in drylands, due to the low number of field experiments testing the pathways behind the long‐term responses of soil respiration (RS) to warming. Importantly, global drylands are covered with biocrusts (communities formed by bryophytes, lichens, cyanobacteria, fungi, and bacteria), and thus, RS responses to warming may be driven by both autotrophic and heterotrophic pathways. Here, we evaluated the effects of 8‐year experimental warming on RS, and the different pathways involved, in a biocrust‐dominated dryland in southern Spain. We also assessed the overall impacts on soil organic C (SOC) accumulation over time. Across the years and biocrust cover levels, warming reduced RS by 0.30 μmol CO2 m?2 s?1 (95% CI = ?0.24 to 0.84), although the negative warming effects were only significant after 3 years of elevated temperatures in areas with low initial biocrust cover. We found support for different pathways regulating the warming‐induced reduction in RS at areas with low (microbial thermal acclimation via reduced soil mass‐specific respiration and β‐glucosidase enzymatic activity) vs. high (microbial thermal acclimation jointly with a reduction in autotrophic respiration from decreased lichen cover) initial biocrust cover. Our 8‐year experimental study shows a reduction in soil respiration with warming and highlights that biocrusts should be explicitly included in modeling efforts aimed to quantify the soil C–climate feedback in drylands. 相似文献
6.
David A. Lipson Russell K. Monson Steven K. Schmidt Michael N. Weintraub 《Biogeochemistry》2009,95(1):23-35
Soil microbial respiration is a critical component of the global carbon cycle, but it is uncertain how properties of microbes
affect this process. Previous studies have noted a thermodynamic trade-off between the rate and efficiency of growth in heterotrophic
organisms. Growth rate and yield determine the biomass-specific respiration rate of growing microbial populations, but these
traits have not previously been used to scale from microbial communities to ecosystems. Here we report seasonal variation
in microbial growth kinetics and temperature responses (Q10) in a coniferous forest soil, relate these properties to cultured and uncultured soil microbes, and model the effects of
shifting growth kinetics on soil heterotrophic respiration (Rh). Soil microbial communities from under-snow had higher growth rates and lower growth yields than the summer and fall communities
from exposed soils, causing higher biomass-specific respiration rates. Growth rate and yield were strongly negatively correlated.
Based on experiments using specific growth inhibitors, bacteria had higher growth rates and lower yields than fungi, overall,
suggesting a more important role for bacteria in determining Rh. The dominant bacteria from laboratory-incubated soil differed seasonally: faster-growing, cold-adapted Janthinobacterium species dominated in winter and slower-growing, mesophilic Burkholderia and Variovorax species dominated in summer. Modeled Rh was sensitive to microbial kinetics and Q10: a sixfold lower annual Rh resulted from using kinetic parameters from summer versus winter communities. Under the most realistic scenario using seasonally
changing communities, the model estimated Rh at 22.67 mol m−2 year−1, or 47.0% of annual total ecosystem respiration (Re) for this forest. 相似文献
7.
O. R. Anderson 《The Journal of eukaryotic microbiology》2014,61(1):11-16
Although tundra terrestrial ecology is significantly affected by global warming, we know relatively little about how eukaryotic microbial communities respond and how much microbial respiratory CO2 may be released due to available organic nutrient sources in the permafrost melt. Prior research has shown a strong positive correlation between bacteria and fungi in some Arctic locales; this research focused on the relationships of terrestrial bacteria and heterotrophic nanoflagellates. The densities and estimated C‐biomass of bacteria and heterotrophic nanoflagellates (a major occurring group of protozoa) were assessed in 14 samples obtained along a 10 km transect in northwest AK during the summer of 2012. Two samples were taken, one at the top and one near the base of seven hummocks along the transect. Densities (no./g soil) of bacteria varied from 2.7–16 × 109, and nanoflagellates 0.7–7.9 × 107. C‐biomass (μg/g soil) of bacteria varied from 358 to 2,114, and nanoflagellates 12–37. Additionally, the rate of respiration was analyzed in the laboratory for each soil sample. A linear relationship between soil respiration and bacterial densities was obtained (20 °C): Rs = 12.32 + 14.07 Bd (p ? 0.01); where Rs is soil respiration (nmol/min/g soil) and Bd = bacterial density (no. × 109/g soil). 相似文献
8.
Differential effects of warming and nitrogen fertilization on soil respiration and microbial dynamics in switchgrass croplands
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Jianwei Li Siyang Jian Jason P. de Koff Chad S. Lane Gangsheng Wang Melanie A. Mayes Dafeng Hui 《Global Change Biology Bioenergy》2018,10(8):565-576
The mechanistic understanding of warming and nitrogen (N) fertilization, alone or in combination, on microbially mediated decomposition is limited. In this study, soil samples were collected from previously harvested switchgrass (Panicum virgatum L.) plots that had been treated with high N fertilizer (HN: 67 kg N ha?1) and those that had received no N fertilizer (NN) over a 3‐year period. The samples were incubated for 180 days at 15 °C and 20 °C, during which heterotrophic respiration, δ13C of CO2, microbial biomass (MB), specific soil respiration rate (Rs: respiration per unit of microbial biomass), and exoenzyme activities were quantified at 10 different collections time. Employing switchgrass tissues (referred to as litter) with naturally abundant 13C allowed us to partition CO2 respiration derived from soil and amended litter. Cumulative soil respiration increased significantly by 16.4% and 4.2% under warming and N fertilization, respectively. Respiration derived from soil was elevated significantly with warming, while oxidase, the agent for recalcitrant soil substrate decomposition, was not significantly affected by warming. Warming, however, significantly enhanced MB and Rs indicating a decrease in microbial growth efficiency (MGE). On the contrary, respiration derived from amended litter was elevated with N fertilization, which was consistent with the significantly elevated hydrolase. N fertilization, however, had little effect on MB and Rs, suggesting little change in microbial physiology. Temperature and N fertilization showed minimal interactive effects likely due to little differences in soil N availability between NN and HN samples, which is partly attributable to switchgrass biomass N accumulation (equivalent to ~53% of fertilizer N). Overall, the differential individual effects of warming and N fertilization may be driven by physiological adaptation and stimulated exoenzyme kinetics, respectively. The study shed insights on distinct microbial acquisition of different substrates under global temperature increase and N enrichment. 相似文献
9.
We examined the possibility that microbial adaptation to temperature could affect rates of CO2, N2O and CH4 release from soils. Laboratory incubations were used to determine the functional relationship between temperature and CO2, N2O and CH4 fluxes for five soils collected across an elevational range in Hawaii. Initial rates of CO2 production and net N mineralization increased exponentially from 15 °C to 55 °C; initial rates of CH4 and N2O release were more complex. No optimum temperature (in which rates decline at higher and lower temperatures) was apparent for any of the gases, but respiration declined with time at higher temperatures, suggesting rapid depletion of readily available substrate. Mean Q10S for respiration varied from 1.4 to 2.0, a typical range for tropical soils. The functional relationship between CO2 production and temperature was consistent among all five soils, despite the substantial differences in mean annual temperature, soils, and land-use among the sites. Temperature responses of N2O and CH4 fluxes did not follow simple Q10 relationships suggesting that temperature functions developed for CO2 release from heterotrophic respiration cannot be simply extrapolated. Expanding this study to tropical heterotrophic respiration, the flux is more sensitive to changes in Q10 than to changes in temperature on a per unit basis: the partial derivative with respect to temperature is 2.4 Gt C ·° C?1 with respect to Q10, it is 3.5 Gt C · Q10 unit?1. Therefore, what appears to be minor variability might still produce substantial uncertainty in regional estimates of gas exchange. 相似文献
10.
Panagiotis Dalias Jonathan M. Anderson Pierre Bottner Marie‐Madeleine Coûteaux 《Global Change Biology》2001,7(2):181-192
14C‐labelled straw was mixed with soils collected from seven coniferous forests located on a climatic gradient in Western Europe ranging from boreal to Mediterranean conditions. The soils were incubated in the laboratory at 4°, 10°, 16°, 23° and 30 °C with constant moisture over 550 days. The temperature coefficient (Q10) for straw carbon mineralization decreased with increasing incubation temperatures. This was a characteristic of all the soils with a difference of two Q10 units between the 4–10° and the 23? 30 °C temperature ranges. It was also found that the magnitude of the temperature response function was related to the period of soil incubation. Initial temperature responses of microbial communities were different to those shown after a long period of laboratory incubation and may have reflected shifts in microbial species composition in response to changes in the temperature regime. The rapid exhaustion of the labile fractions of the decomposing material at higher temperatures could also lead to underestimation of the temperature sensitivity of soils unless estimated for carbon pools of similar qualities. Finally, the thermal optima for the organic soil horizons (Of and Oh) were lower than 30 °C even after 550 days of incubation. It was concluded that these responses could not be attributed to microbial physiological adaptations, but rather to the rates at which recalcitrant microbial secondary products were formed at higher temperatures. The implication of these variable temperature responses of soil materials is discussed in relation to modelling potential effects of global warming. 相似文献
11.
Kyungjin Min Kate Buckeridge Susan E. Ziegler Kate A. Edwards Samik Bagchi Sharon A. Billings 《Global Change Biology》2019,25(5):1793-1807
Accurate representation of temperature sensitivity (Q10) of soil microbial activity across time is critical for projecting soil CO2 efflux. As microorganisms mediate soil carbon (C) loss via exo‐enzyme activity and respiration, we explore temperature sensitivities of microbial exo‐enzyme activity and respiratory CO2 loss across time and assess mechanisms associated with these potential changes in microbial temperature responses. We collected soils along a latitudinal boreal forest transect with different temperature regimes (long‐term timescale) and exposed these soils to laboratory temperature manipulations at 5, 15, and 25°C for 84 days (short‐term timescale). We quantified temperature sensitivity of microbial activity per g soil and per g microbial biomass at days 9, 34, 55, and 84, and determined bacterial and fungal community structure before the incubation and at days 9 and 84. All biomass‐specific rates exhibited temperature sensitivities resistant to change across short‐ and long‐term timescales (mean Q10 = 2.77 ± 0.25, 2.63 ± 0.26, 1.78 ± 0.26, 2.27 ± 0.25, 3.28 ± 0.44, 2.89 ± 0.55 for β‐glucosidase, N‐acetyl‐β‐d ‐glucosaminidase, leucine amino peptidase, acid phosphatase, cellobiohydrolase, and CO2 efflux, respectively). In contrast, temperature sensitivity of soil mass‐specific rates exhibited either resilience (the Q10 value changed and returned to the original value over time) or resistance to change. Regardless of the microbial flux responses, bacterial and fungal community structure was susceptible to change with temperature, significantly differing with short‐ and long‐term exposure to different temperature regimes. Our results highlight that temperature responses of microbial resource allocation to exo‐enzyme production and associated respiratory CO2 loss per unit biomass can remain invariant across time, and thus, that vulnerability of soil organic C stocks to rising temperatures may persist in the long term. Furthermore, resistant temperature sensitivities of biomass‐specific rates in spite of different community structures imply decoupling of community constituents and the temperature responses of soil microbial activities. 相似文献
12.
Effects of temperature,soil substrate,and microbial community on carbon mineralization across three climatically contrasting forest sites
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Zuoxin Tang Xiaolu Sun Zhongkui Luo Nianpeng He Osbert Jianxin Sun 《Ecology and evolution》2018,8(2):879-891
How biotic and abiotic factors influence soil carbon (C) mineralization rate (RS) has recently emerged as one of the focal interests in ecological studies. To determine the relative effects of temperature, soil substrate and microbial community on Rs, we conducted a laboratory experiment involving reciprocal microbial inoculations of three zonal forest soils, and measured RS over a 61‐day period at three temperatures (5, 15, and 25°C). Results show that both Rs and the cumulative emission of C (Rcum), normalized to per unit soil organic C (SOC), were significantly affected by incubation temperature, soil substrate, microbial inoculum treatment, and their interactions (p < .05). Overall, the incubation temperature had the strongest effect on the RS; at given temperatures, soil substrate, microbial inoculum treatment, and their interaction all significantly affected both Rs (p < .001) and Rcum (p ≤ .01), but the effect of soil substrate was much stronger than others. There was no consistent pattern of thermal adaptation in microbial decomposition of SOC in the reciprocal inoculations. Moreover, when different sources of microbial inocula were introduced to the same soil substrate, the microbial community structure converged with incubation without altering the overall soil enzyme activities; when different types of soil substrate were inoculated with the same sources of microbial inocula, both the microbial community structure and soil enzyme activities diverged. Overall, temperature plays a predominant role in affecting Rs and Rcum, while soil substrate determines the mineralizable SOC under given conditions. The role of microbial community in driving SOC mineralization is weaker than that of climate and soil substrate, because soil microbial community is both affected, and adapts to, climatic factors and soil matrix. 相似文献
13.
Soils are the largest store of carbon in the biosphere and cool‐cold climate ecosystems are notable for their carbon‐rich soils. Characterizing effects of future climates on soil‐stored C is critical to elucidating feedbacks to changes in the atmospheric pool of CO2. Subalpine vegetation in south‐eastern Australia is characterized by changes over short distances (scales of tens to hundreds of metres) in community phenotype (woodland, shrubland, grassland) and in species composition. Despite common geology and only slight changes in landscape position, we measured striking differences in a range of soil properties and rates of respiration among three of the most common vegetation communities in subalpine Australian ecosystems. Rates of heterotrophic respiration in bulk soil were fastest in the woodland community with a shrub understorey, slowest in the grassland, and intermediate in woodland with grass understorey. Respiration rates in surface soils were 2.3 times those at depth in soils from woodland with shrub understorey. Surface soil respiration in woodlands with grass understorey and in grasslands was about 3.5 times that at greater depth. Both Arrhenius and simple exponential models fitted the data well. Temperature sensitivity (Q10) varied and depended on the model used as well as community type and soil depth – highlighting difficulties associated with calculating and interpreting Q10. Distributions of communities in these subalpine areas are dynamic and respond over relatively short time‐frames (decades) to changes in fire regime and, possibly, to changes in climate. Shifts in boundaries among communities and possible changes in species composition as a result of both direct and indirect (e.g. via fire regime) climatic effects will significantly alter rates of respiration through plant‐mediated changes in soil chemistry. Models of future carbon cycles need to take into account changes in soil chemistry and rates of respiration driven by changes in vegetation as well as those that are temperature‐ and moisture‐driven. 相似文献
14.
Vidya Suseela Richard T. Conant Matthew D. Wallenstein Jeffrey S. Dukes 《Global Change Biology》2012,18(1):336-348
Microbial decomposition of soil organic matter produces a major flux of CO2 from terrestrial ecosystems and can act as a feedback to climate change. Although climate‐carbon models suggest that warming will accelerate the release of CO2 from soils, the magnitude of this feedback is uncertain, mostly due to uncertainty in the temperature sensitivity of soil organic matter decomposition. We examined how warming and altered precipitation affected the rate and temperature sensitivity of heterotrophic respiration (Rh) at the Boston‐Area Climate Experiment, in Massachusetts, USA. We measured Rh inside deep collars that excluded plant roots and litter inputs. In this mesic ecosystem, Rh responded strongly to precipitation. Drought reduced Rh, both annually and during the growing season. Warming increased Rh only in early spring. During the summer, when Rh was highest, we found evidence of threshold, hysteretic responses to soil moisture: Rh decreased sharply when volumetric soil moisture dropped below ~15% or exceeded ~26%, but Rh increased more gradually when soil moisture rose from the lower threshold. The effect of climate treatments on the temperature sensitivity of Rh depended on the season. Apparent Q10 decreased with high warming (~3.5 °C) in spring and fall. Presumably due to limiting soil moisture, warming and precipitation treatments did not affect apparent Q10 in summer. Drought decreased apparent Q10 in fall compared to ambient and wet precipitation treatments. To our knowledge, this is the first field study to examine the response of Rh and its temperature sensitivity to the combined effects of warming and altered precipitation. Our results highlight the complex responses of Rh to soil moisture, and to our knowledge identify for the first time the seasonal variation in the temperature sensitivity of microbial respiration in the field. We emphasize the importance of adequately simulating responses such as these when modeling trajectories of soil carbon stocks under climate change scenarios. 相似文献
15.
Carbon limitation of soil respiration under winter snowpacks: potential feedbacks between growing season and winter carbon fluxes 总被引:9,自引:0,他引:9
A reduction in the length of the snow‐covered season in response to a warming of high‐latitude and high‐elevation ecosystems may increase soil carbon availability both through increased litter fall following longer growing seasons and by allowing early winter soil frosts that lyse plant and microbial cells. To evaluate how an increase in labile carbon during winter may affect ecosystem carbon balance we investigated the relationship between carbon availability and winter CO2 fluxes at several locations in the Colorado Rockies. Landscape‐scale surveys of winter CO2 fluxes from sites with different soil carbon content indicated that winter CO2 fluxes were positively related to carbon availability and experimental additions of glucose to soil confirmed that CO2 fluxes from snow‐covered soil at temperatures between 0 and ?3°C were carbon limited. Glucose added to snow‐covered soil increased CO2 fluxes by 52–160% relative to control sites within 24 h and remained 62–70% higher after 30 days. Concurrently a shift in the δ13C values of emitted CO2 toward the glucose value indicated preferential utilization of the added carbon confirming the presence of active heterotrophic respiration in soils at temperatures below 0°C. The sensitivity of these winter fluxes to substrate availability, coupled with predicted changes in winter snow cover, suggests that feedbacks between growing season carbon uptake and winter heterotrophic activity may have unforeseen consequences for carbon and nutrient cycling in northern forests. For example, published winter CO2 fluxes indicate that on average 50% of growing season carbon uptake currently is respired during the winter; changes in winter CO2 flux in response to climate change have the potential to reduce substantially the net carbon sink in these ecosystems. 相似文献
16.
The western Antarctic Peninsula is an extreme low temperature environment that is warming rapidly due to global change. Little is known, however, on the temperature sensitivity of growth of microbial communities in Antarctic soils and in the surrounding oceanic waters. This is the first study that directly compares temperature adaptation of adjacent marine and terrestrial bacteria in a polar environment. The bacterial communities in the ocean were adapted to lower temperatures than those from nearby soil, with cardinal temperatures for growth in the ocean being the lowest so far reported for microbial communities. This was reflected in lower minimum (Tmin) and optimum temperatures (Topt) for growth in water (?17 and +20°C, respectively) than in soil (?11 and +27°C), with lower sensitivity to changes in temperature (Q10; 0–10°C interval) in Antarctic water (2.7) than in soil (3.9). This is likely due to the more stable low temperature conditions of Antarctic waters than soils, and the fact that maximum in situ temperatures in water are lower than in soils, at least in summer. Importantly, the thermally stable environment of Antarctic marine water makes it feasible to create a single temperature response curve for bacterial communities. This would thus allow for calculations of temperature‐corrected growth rates, and thereby quantifying the influence of factors other than temperature on observed growth rates, as well as predicting the effects of future temperature increases on Antarctic marine bacteria. 相似文献
17.
Site and temporal variation of soil respiration in European beech, Norway spruce, and Scots pine forests 总被引:15,自引:0,他引:15
WERNER BORKEN‡ YI-JUN XU† ERIC A. DAVIDSON‡ FRIEDRICH BEESE 《Global Change Biology》2002,8(12):1205-1216
Global warming and changes in rainfall amount and distribution may affect soil respiration as a major carbon flux between the biosphere and the atmosphere. The objectives of this study were to investigate the site to site and interannual variation in soil respiration of six temperate forest sites. Soil respiration was measured using closed chambers over 2 years under mature beech, spruce and pine stands at both Solling and Unterlüß, Germany, which have distinct climates and soils. Cumulative annual CO2 fluxes varied from 4.9 to 5.4 Mg C ha?1 yr?1 at Solling with silty soils and from 4.0 to 5.9 Mg C ha?1 yr?1 at Unterlüß with sandy soils. With one exception soil respiration rates were not significantly different among the six forest sites (site to site variation) and between the years within the same forest site (interannual variation). Only the respiration rate in the spruce stand at Unterlüß was significant lower than the beech stand at Unterlüß in both years. Soil respiration rates of the sandy sites at Unterlüß were limited by soil moisture during the rather dry and warm summer 1999 while soil respiration at the silty Solling site tended to increase. We found a threshold of ?80 kPa at 10 cm depth below which soil respiration decreased with increasing drought. Subsequent wetting of sandy soils revealed high CO2 effluxes in the stands at Unterlüß. However, dry periods were infrequent, and our results suggest that temporal variation in soil moisture generally had little effect on annual soil respiration rates. Soil temperature at 5 cm and 10 cm depth explained 83% of the temporal variation in soil respiration using the Arrhenius function. The correlations were weaker using temperature at 0 cm (r2 = 0.63) and 2.5 cm depth (r2 = 0.81). Mean Q10 values for the range from 5 to 15 °C increased asymptotically with soil depth from 1.87 at 0 cm to 3.46 at 10 cm depth, indicating a large uncertainty in the prediction of the temperature dependency of soil respiration. Comparing the fitted Arrhenius curves for same tree species from Solling and Unterlüß revealed higher soil respiration rates for the stands at Solling than in the respective stands at Unterlüß at the same temperature. A significant positive correlation across all sites between predicted soil respiration rates at 10 °C and total phosphorus content and C‐to‐N ratio of the upper mineral soil indicate a possible effect of nutrients on soil respiration. 相似文献
18.
Andrew T. Nottingham Erland Bth Stephanie Reischke Norma Salinas Patrick Meir 《Global Change Biology》2019,25(3):827-838
Terrestrial biogeochemical feedbacks to the climate are strongly modulated by the temperature response of soil microorganisms. Tropical forests, in particular, exert a major influence on global climate because they are the most productive terrestrial ecosystem. We used an elevation gradient across tropical forest in the Andes (a gradient of 20°C mean annual temperature, MAT), to test whether soil bacterial and fungal community growth responses are adapted to long‐term temperature differences. We evaluated the temperature dependency of soil bacterial and fungal growth using the leucine‐ and acetate‐incorporation methods, respectively, and determined indices for the temperature response of growth: Q10 (temperature sensitivity over a given 10oC range) and Tmin (the minimum temperature for growth). For both bacterial and fungal communities, increased MAT (decreased elevation) resulted in increases in Q10 and Tmin of growth. Across a MAT range from 6°C to 26°C, the Q10 and Tmin varied for bacterial growth (Q10–20 = 2.4 to 3.5; Tmin = ?8°C to ?1.5°C) and fungal growth (Q10–20 = 2.6 to 3.6; Tmin = ?6°C to ?1°C). Thus, bacteria and fungi did not differ significantly in their growth temperature responses with changes in MAT. Our findings indicate that across natural temperature gradients, each increase in MAT by 1°C results in increases in Tmin of microbial growth by approximately 0.3°C and Q10–20 by 0.05, consistent with long‐term temperature adaptation of soil microbial communities. A 2°C warming would increase microbial activity across a MAT gradient of 6°C to 26°C by 28% to 15%, respectively, and temperature adaptation of microbial communities would further increase activity by 1.2% to 0.3%. The impact of warming on microbial activity, and the related impact on soil carbon cycling, is thus greater in regions with lower MAT. These results can be used to predict future changes in the temperature response of microbial activity over different levels of warming and over large temperature ranges, extending to tropical regions. 相似文献
19.
Andreas Schindlbacher Sophie Zechmeister-Boltenstern Barbara Kitzler Robert Jandl 《Plant and Soil》2008,303(1-2):323-330
We warmed the top soil of a mature coniferous forest stand by means of heating cables on control and trenched plots within
24 h by 10°C at 1 cm soil depth (9°C at 5 cm depth) and measured the effect on the autotrophic (RA) and heterotrophic (RH) component of total soil CO2 efflux (RS). The short time frame of warming enabled us to exclude confounding fluctuations in soil moisture and carbon (C) flow from
the canopy. The results of the field study were backed up by a lab soil incubation experiment. During the first 12 h of warming,
RA strongly responded to soil warming; The Q
10 values were 5.61 and 6.29 for 1 and 5 cm soil depth temperature. The Q
10 values for RA were almost twice as high as the Q
10 values of RH (3.04 and 3.53). Q
10 values above 5 are above reasonable plant physiological values for root respiration. We see interactions of roots, mycorrhizae
and heterotrophic microbes, combined with fast substrate supply to the rhizosphere as an explanation for the high short-term
temperature response of RA. When calculated over the whole duration (24 h) of the field soil-warming experiment, temperature sensitivities of RA and RH were similar (no significant difference at P < 0.05); Q
10 values were 3.16 and 3.96 for RA and 2.94 and 3.35 for RH calculated with soil temperatures at 1 and 5 cm soil depth, respectively. Laboratory incubation showed that different soil
moisture contents of trenched and control plots affected rates of RH, but did not affect the temperature sensitivity of RH. We conclude that a single parameter is sufficient to describe the temperature sensitivity of RS in soil C models which operate on larger temporal and spatial scales. The strong short-term response of RA may be of relevance in soils suspected to experience increasingly strong diurnal temperature variations. 相似文献
20.
Topographic and climatic controls on soil respiration in six temperate mixed-hardwood forest slopes, Korea 总被引:16,自引:0,他引:16
Sinkyu Kang † Sueyoung Doh Dongsun. Lee Dowon. Lee Virginia L. Jin‡ John S. Kimball§ 《Global Change Biology》2003,9(10):1427-1437
To better understand the effects of local topography and climate on soil respiration, we conducted field measurements and soil incubation experiments to investigate various factors influencing spatial and temporal variations in soil respiration for six mixed‐hardwood forest slopes in the midst of the Korean Peninsula. Soil respiration and soil water content (SWC) were significantly greater (P=0.09 and 0.003, respectively) on north‐facing slopes compared to south‐facing slopes, while soil temperature was not significantly different between slopes (P>0.5). At all sites, soil temperature was the primary factor driving temporal variations in soil respiration (r2=0.84–0.96) followed by SWC, which accounted for 30% of soil respiration spatial and temporal variability. Results from both field measurements and incubation experiments indicate that variations in soil respiration due to aspect can be explained by a convex‐shaped function relating SWC to normalized soil respiration rates. Annual soil respiration estimates (1070–1246 g C m?2 yr?1) were not closely related to mean annual air temperatures among sites from different climate regimes. When soils from each site were incubated at similar temperatures in a laboratory, respiration rates for mineral soils from wetter and cooler sites were significantly higher than those for the drier and warmer sites (n=4, P<0.01). Our results indicate that the application of standard temperature‐based Q10 models to estimate soil respiration rates for larger geographic areas covering different aspects or climatic regimes are not adequate unless other factors, such as SWC and total soil nitrogen, are considered in addition to soil temperature. 相似文献