土壤各组分呼吸区分方法研究进展

土壤呼吸分为自养型呼吸(根呼吸)和异养型呼吸(微生物和动物呼吸),区分各组分呼吸可了解在全球变化条件下土壤碳循环和碳平衡的动态。本文综述了3种主要区分自养呼吸和异养呼吸的方法:①组分法;②根去除术;③同位素法。其中同位素法对根和土壤的影响最小,是最可靠的一种方法;综合各方面考虑,根去除法是最切实可行的方法。     

三源区分土壤呼吸组分研究

三源区分土壤呼吸组分是指将土壤呼吸区分为纯根呼吸、根际微生物呼吸和土壤有机质呼吸3个部分。土壤有机质呼吸、纯根呼吸和根际微生物呼吸是3种不同的生物学过程,这3种呼吸对环境变化具有不同的响应机制。区分土壤呼吸中由根系引起的自养和异养呼吸组分的研究对定量评价陆地生态系统碳平衡具有重要的意义。论述了三源区分土壤呼吸组分的意义、方法和应用,分析了不同条件下土壤呼吸组分区分的研究结果。实验室纯根和根际微生物呼吸占根源呼吸比重约为45%和55%;野外条件下约为60%和40%。最后对本研究未来的发展方向进行了展望。     

Respiratory responses of higher plants to atmospheric CO2 enrichment

Although the respiratory response of native and agricultural plants to atmospheric CO₂ enrichment has been reported over the past 75 years, only recently have these effects emerged as prominent measures of plant and ecosystem response to the earth's changing climate. In this review we discuss this rapidly expanding field of study and propose that both increasing and decreasing rates of leaf and whole-plant respiration are likely to occur in response to rising CO₂ concentrations. While the stimulatory effects of CO₂ on respiration are consistent with our knowledge of leaf carbohydrate status and plant metabolism, we wish to emphasize the rather surprising short-term inhibition of leaf respiration by elevated CO₂ and the reported effects of long-term CO₂ exposure on growth and maintenance respiration. As is being found in many studies, it is easier to document the respiratory response of higher plants to elevated CO₂ than it is to assign a mechanistic basis for the observed effects. Despite this gap in our understanding of how respiration is affected by CO₂ enrichment, data are sufficient to suggest that changes in leaf and whole-plant respiration may be important considerations in the carbon dynamics of terrestrial ecosystems as global CO₂ continues to rise. Suggestions for future research that would enable these and other effects of CO₂ on respiration to be unravelled are presented.     

中国森林土壤呼吸模式

通过收集国内62个森林样地的土壤呼吸及相关因子数据,分析中国森林土壤呼吸模式.结果表明,中国森林土壤呼吸年通量与年均气温、年均降水量、年凋落物量和年地上净生产力均呈显著的线性正相关,土壤呼吸的Q10则与年均气温和年均降水量均呈显著的负相关.根系呼吸、枯枝落叶层呼吸与土壤呼吸间均呈显著线性正相关;土壤异养呼吸和枯枝落叶层呼吸与年凋落物量呈显著正相关;土壤异养呼吸与自养呼吸间呈显著的线性正相关.根系呼吸、枯枝落叶层呼吸、矿质土壤呼吸占土壤呼吸的比例均值分别为34.7%、20.2%和50.2%.矿质土壤呼吸所占比例与气温和降水量呈显著负相关,而异养呼吸所占比例则与降水量呈显著负相关.根系呼吸所占比例与根系呼吸之间呈渐近线关系(渐近值为45.9%).     

湖南会同林区毛竹林地的土壤呼吸

采用CID-301PS光合分析仪(配带土壤呼吸室),对湖南会同林区毛竹林地土壤呼吸进行测定,结果表明,毛竹林地土壤总呼吸速率、异养呼吸速率、自养呼吸速率及凋落物呼吸速率的年平均值分别为2.13、1.44、0.69μmolCO2·m-2·s-1和0.31μmolCO2·m-2·s-1,并呈现明显的季节变化规律和日变化规律,季节变化曲线呈单峰型,表现为1～7月份随着气温、地温的升高呈上升的趋势,在8月达年呼吸速率的最大值,分别达4.95、3.01、1.94μmolCO2·m-2·s-1和0.80 μmolCO2·m-2·s-1,此后随温度的降低而呈逐渐递减的趋势,直到翌年的1月份或2月份,分别为0.76、0.70、 0.06μmolCO2·m-2·s-1 和 0.05μmolCO2·m-2·s-1.日变化曲线图表现为单峰形态,一般也是随着温度的升高而加大,随着温度的降低而减小.6:00～14:00,随着土壤温度的升高而增加,一般在16:00～18:00出现最高峰,此后,一直递减,直到次日4:00～8:00.由此计算出毛竹林地土壤年释放CO2量为33.94 t·hm-2·a-1,其中,林地异养呼吸、自养呼吸和凋落物呼吸分别占总呼吸的59.5%、28.3%和12.2%.     

Does the different photosynthetic pathway of plants affect soil respiration in a subtropical wetland?

Plants with different photosynthetic pathways could produce different amounts and types of root exudates and debris which may affect soil respiration rates. Therefore, wetland vegetation succession between plants with different photosynthetic pathways may ultimately influence the wetland carbon budget. The middle and lower reaches of the Yangtze River has the largest floodplain wetland group in China. Tian'e Zhou wetland reserve (29°48'N, 112°33′E) is located in Shishou city, Hubei province and covers about 77.5 square kilometers. Hemathria altissima (C4) was found gradually being replaced by Carex argyi (C3) for several years in this place. An in situ experiment was conducted in Tian'e Zhou wetland to determine the change of soil respiration as the succession proceeds. Soil respiration, substrate‐induced respiration, and bacterial respiration of the C4 species was greater than those of the C3 species, but below‐ground biomass and fungal respiration of the C4 species was less than that of the C3 species. There were no significant differences in above‐ground biomass between the two species. Due to the higher photosynthesis capability, higher soil respiration and lower total plant biomass, we inferred that the C4 species, H. altissima, may transport more photosynthate below‐ground as a substrate for respiration. The photosynthetic pathway of plants might therefore play an important role in regulating soil respiration. As C. argyi replaces H. altissima, the larger plant biomass and lower soil respiration would indicate that the wetland in this area could fix more carbon in the soil than before.     

土壤微生物与根系呼吸作用影响因子分析

土壤呼吸作用作为陆地生态系统碳循环的重要组成部分,是当前碳循环研究中的热点问题.对于土壤呼吸作用主要组成部分土壤微生物呼吸作用和根系呼吸作用影响因子的研究,有助于准确地评估全球碳收支.本文从气候、土壤、植被及地表覆被物、大气CO₂浓度、人为干扰等方面综述了土壤微生物呼吸作用和根系呼吸作用的主导影响因子,指出这些影响因子不仅直接或间接地影响土壤微生物呼吸作用和根系呼吸作用,而且它们之间相互作用、相互影响,且各影响因子的地位和作用会随时空尺度变化发生相应改变.在此基础上,论文提出了未来土壤呼吸作用的研究重点.     

马尾松林土壤呼吸组分对不同营林措施的响应

针对不同营林措施(对照、除灌、采伐1(15%)、采伐2(70%)后的三峡库区马尾松飞播林,采用LI-8100对其土壤呼吸组分的呼吸速率和土壤温度、湿度进行为期1年的连续观测分析表明,不同营林措施对土壤呼吸组分的影响不同。1)观测期内,各营林措施下凋落物层呼吸速率差异并不显著,对照、除灌、采伐1、采伐2的根呼吸速率均值分别为:1.00、0.83、0.86、1.11μmolCO_2m~(-2)s~(-1);采伐处理下矿质土壤呼吸显著高于对照和除灌(P0.05);2)与对照相比,营林措施并未显著改变凋落物呼吸对于土壤总呼吸的贡献率(18.78%-23.70%),但降低了根呼吸的贡献率,其中以采伐1最为显著(P0.05);除灌的矿质土壤呼吸贡献率(37.00%)与对照(38.32%)相近,而采伐1(45.63%)和采伐2(43.07%)均显著增加了矿质土壤呼吸的贡献率,矿质土壤呼吸的变化是造成采伐措施下土壤呼吸变化的主要土壤呼吸组分;3)营林后仅采伐2措施下土壤温湿度显著高于对照,土壤温湿度双因子模型较单因子模型能更好的解释土壤呼吸组分变化,但仅能解释其部分变化(4.6%-59.3%),仍需对营林后其他相关因子进行深入的综合研究。     

青藏高原东缘亚高山针叶林人工恢复过程中的土壤呼吸特征

采用动态密闭气室红外CO₂分析法,对青藏高原东缘云杉人工林的土壤呼吸进行连续定位测定,并用挖壕沟法区分土壤自养呼吸和异养呼吸.结果表明:4种云杉林的土壤呼吸速率与土壤5 cm层温度有显著的正指数关系,与土壤含水量的相关性不显著.4种云杉林土壤呼吸年通量在792.08～1070.20 g C·m^-2·a^-1,大小依次为：天然云杉林＞22年生云杉人工林＞65年生云杉人工林＞35年生云杉人工林,随着人工林的恢复呈先降低后升高的趋势.在森林恢复过程中,人工云杉土壤自养和异养呼吸年通量均先减少后增加, 在253.36～357.05 g C·m^-2·a^-1和538.69～703.82 g C·m^-2·a^-1范围变化.22年生、35年生、65年生云杉人工林和天然云杉林非生长季 （2007-11-2008-03）和生长季（2008-04-2008-10）的Q₁₀值分别为：4.59、6.54、4.77、3.18和4.17、4.66、3.11、2.74.除22年生云杉人工林,Q₁₀值随云杉林的恢复更新而逐渐降低, 且非生长季节Q₁₀值均明显高于生长季节.     

Pyrobaculum calidifontis sp. nov., a novel hyperthermophilic archaeon that grows in atmospheric air

A novel, facultatively aerobic, heterotrophic hyperthermophilic archaeon was isolated from a terrestrial hot spring in the Philippines. Cells of the new isolate, strain VA1, were rod-shaped with a length of 1.5 to 10 microm and a width of 0.5 to 1.0 microm. Isolate VA1 grew optimally at 90 to 95 degrees C and pH 7.0 in atmospheric air. Oxygen served as a final electron acceptor under aerobic growth conditions, and vigorous shaking of the medium significantly enhanced growth. Elemental sulfur inhibited cell growth under aerobic growth conditions, whereas thiosulfate stimulated cell growth. Under anaerobic growth conditions, nitrate served as a final electron acceptor, but nitrite or sulfur-containing compounds such as elemental sulfur, thiosulfate, sulfate and sulfite could not act as final electron acceptors. The G+C content of the genomic DNA was 51 mol%. Phylogenetic analysis based on 16S rRNA sequences indicated that strain VA1 exhibited close relationships to species of the genus Pyrobaculum. A DNA-DNA hybridization study revealed a low level of similarity (< or = 18%) between strain VA1 and previously described members of the genus Pyrobaculum. Physiological characteristics also indicated that strain VA1 was distinct from these Pyrobaculum species. Our results indicate that isolate VA1 represents a novel species, named Pyrobaculum calidifontis.     

小兴安岭4种原始红松林群落类型生长季土壤呼吸特征

为阐明小兴安岭地带性植被原始红松林土壤呼吸各组分的碳排放速率及其对土壤水热变化的响应规律,采用挖壕法和红外气体分析法测定土壤表面CO2通量(Rs),确定4种原始红松林群落类型生长季的土壤总呼吸(Rt)中土壤微生物呼吸(Rh),根系呼吸(Rr)和凋落物呼吸(Rl)的贡献量动态变化及其影响因子。结果表明:生长季内,4种原始红松林群落类型的Rt、Rh、Rr具有明显的季节性变化,7-9月份较高,6月份和10月份较低。Rh对Rt的贡献量最高,平均在58.8%;Rr对Rt的贡献量次之,平均为26.5%;Rl对Rt的贡献量相对较小,平均为12.5%。生长季土壤呼吸速率与5cm深土壤温度相关性极显著(P0.01)。Rr和Rh的Q10值分别为2.88和2.23。表明根呼吸对土壤温度的敏感性高于微生物呼吸。生长季平均土壤呼吸速率的依次为:椴树红松林(6.38μmol·m-·2s-1)云冷杉红松林(6.32μmol·m-·2s-1)枫桦红松林(5.95μmol·m-·2s-1)蒙古栎红松林(2.86μmol·m-·2s-1)。4种原始叶红松林群落类型间的Rh和Rr也存在一定差异。     

Growing season ecosystem respirations and associated component fluxes in two alpine meadows on the Tibetan Plateau

From 30 June to 24 September in 2003 ecosystem respiration （Re） in two alpine meadows on the Tibetan Plateau were measured using static chamber- and gas chromatography- （GC） based techniques. Simultaneously, plant removal treatments were set to partition Re into plant autotrophic respiration （Ra） and microbial heterotrophic respiration （Rh）. Results indicated that Re had clear diurnal and seasonal variation patterns in both of the meadows. The seasonal variability of Re at both meadow sites was caused mainly by changes in Ra, rather than Rh. Moreover, atthe Kobresia humilis meadow site （K_site）, Ra and Rh accounted for 54% and 46% of Re, respectively. While at the Potentilla fruticosa scrub meadow （P_site）, the counterparts accounted for 61% and 39%, respectively. T test showed that there was significant difference in Re rates between the two meadows （t = 2.387, P = 0.022）. However, no significant difference was found in Rh rates, whereas a significant difference was observed in Ra rates between the two meadows. Thus, the difference in Re rate between the two meadows was mainly attributed to plant autotrophic respirations. During the growing season, the two meadows showed relatively low Q10 values, suggesting that Re, especially Rh was not sensitive to temperature variation in the growing season. Additionally, Re and Rh at the K_site, as well as Rh at the Psite was negatively correlated with soil moisture, indicating that soil moisture would also play an important role in respirations.     

土壤-玉米系统中土壤呼吸强度及各组分贡献

用特殊设计的气体采集箱法对玉米生长期间潮土呼吸强度进行了测定。结果表明,施用150kgNhm^-2的裸地土壤CO2累积排放量是294g C m^-2,约为种植玉米土壤的一半。用根去除法测得的玉米对土壤呼吸的贡献率,苗期小于20％,拔节到收获期波动在30％-70％之间,全生长期平均为46％。玉米生长期间因土壤有机碳分解而释放出的CO2总量为2．94MgChm^-2,大约是0—40cm土层中土壤有机碳总储存量的8％,因此需要输入7．35Mghm^-2的碳含量40％的作物残留物才能平衡土壤中有机碳的损失,约为玉米收获时残留于土壤中根量的一倍,但与残留根量及玉米生长期间根系分泌到土壤的有机物量的总和相当,因此土壤中有机碳总体处于平衡状态。在玉米生长期间,施用氮肥可使土壤CO2排放量降低10％。土壤排放CO2主要受土壤温度的影响,温度效应Q10为1．90-2．88。     

Differential responses of auto‐ and heterotrophic soil respiration to water and nitrogen addition in a semiarid temperate steppe

Evaluating how autotrophic (SR_A), heterotrophic (SR_H) and total soil respiration (SR_TOT) respond differently to changes of environmental factors is critical to get an understanding of ecosystem carbon (C) cycling and its feedback processes to climate change. A field experiment was conducted to examine the responses of SR_A and SR_H to water and nitrogen (N) addition in a temperate steppe in northern China during two hydrologically contrasting growing seasons. Water addition stimulated SR_A and SR_H in both years, and their increases were significantly greater in a dry year (2007) than in a wet year (2006). N addition increased SR_A in 2006 but not in 2007, while it decreased SR_H in both years, leading to a positive response of SR_TOT in 2006 but a negative one in 2007. The different responses of SR_A and SR_H indicate that it will be uncertain to predict soil C storage if SR_TOT is used instead of SR_H to estimate variations in soil C storage. Overall, N addition is likely to enhance soil C storage, while the impacts of water addition are determined by its relative effects on carbon input (plant growth) and SR_H. Antecedent water conditions played an important role in controlling responses of SR_A, SR_H and the consequent SR_TOT to water and N addition. Our findings highlight the predominance of hydrological conditions in regulating the responses of C cycling to global change in the semiarid temperate steppe of northern China.     

土壤呼吸组分分离技术研究进展

分离土壤呼吸组分是理解陆地生态系统碳循环的重要步骤,研究农田生态系统土壤呼吸组分的呼吸过程和机理对促进农业温室气体减排和碳汇增加、气候变化适应、保障粮食安全以及推动农业可持续发展都具有积极意义。本文综述了近年来土壤呼吸组分分离的理论依据、主要技术及分类,系统比较了现有技术优势、劣势和应用领域,并总结了土壤呼吸组分分离技术在国内外农田生态系统中的应用情况。由于多数分离技术在森林生态系统的相关研究中发展而来,它们在农田生态系统的应用十分有限,目前应用以同位素法、根分离法和回归法为主。由于土壤呼吸理论划分和分离方法的差异,不同研究结果之间往往难以比较。分离技术的发展有赖于土壤呼吸源分离理论的进一步发展,未来土壤呼吸组分分离研究的主要方向在于：（1）利用现有观测技术促进组分集成分析法和根分离法在农田生态系统中的应用,强化土壤呼吸组分和环境因子的同步观测,准确评估农田碳收支;（2）利用定位观测数据开展大尺度模型研究,改进和重构现有全球碳模型的碳氮过程,并在其中考虑重要的土壤呼吸过程;（3）利用FACE试验评估气候变化对土壤呼吸组分的影响和土壤-植物碳循环的适应机制;（4）分析呼吸组分与植物-土壤-养分的交互作用,评估农田管理措施的综合影响。     

Plants at high altitude exhibit higher component of alternative respiration

Total respiration, capacities of cytochrome (CytR) and alternative respiration (AR) were studied in two varieties of barley (Horedum vulgare) and wheat (Triticum aestivum) each and one variety of pea (Pisum sativum) at low (Palampur; 1300 m) and high altitudes (Kibber; 4200 m). Similar studies were carried out in naturally growing Rumex nepalensis and Trifoilum repenses at Palampur, Palchan (2250 m) and Marhi (3250 m). All the plants species exhibited lower CytR but significantly higher AR capacity at high altitude (HA) (72-1117% higher) as compared to those at low altitude (LA). Glycolytic product, pyruvate and tricarboxylic acid cycle intermediate, citrate increased with increase in altitude. While the role of these metabolites in relation to HA biology is discussed, significantly higher AR at HA is proposed to be an adaptive mechanism against the metabolic perturbations wherein it might act to lower reactive oxygen species and also provides metabolic homeostasis to plants under the environment of HA.     

南方型杨树人工林土壤呼吸及其组分分析

采用开沟隔离法,利用LI-8100型土壤呼吸测定系统,对15年生的南方型杨树(Populus deltoides)人工林土壤呼吸进行了研究,并试图区分根系呼吸和土壤微生物呼吸。结果表明,开沟隔离处理后的10个月内,由于土壤中被截断根系具有自养呼吸和分解作用,土壤呼吸中的根系呼吸与微生物呼吸尚难以区分。尽管如此,研究表明15年生杨树人工林的土壤总呼吸通量为9.74 tC.hm-.2a-1,其中,枯枝落叶等土壤表层凋落物分解所释放的碳通量是2.63 tC.hm-.2a-1,占总量的27.0%;林木根系呼吸与土壤微生物呼吸通量的和为7.11 tC.hm-.2a-1,占总量的73.0%。土壤各组分呼吸速率与10 cm深处的土壤温度之间存在着显著的指数函数关系。不同直径的杨树根系被截断后的活力变化有所不同,根系越粗,存活时间越长。     

Effects of cyanide, salicylhydroxamic acid, and temperature on respiration and germination of spores of the fern Sphaeropteris cooperi

During the first 96 h of culture, germinating spores of the fern Sphaeropteris cooperi (F. v. Muell.) Tryon showed a gradual rise in respiratory activity to a maximum of about 6.5 μl 0₂ h⁻¹ mg⁻¹ dry wt. This was followed by a transitory decline in rate, concluded by a second respiratory rise preceding the emergence of the rhizoid after 192 h of culture. Oxygen uptake during the first 120 h of germination was insensitive to 1 m M potassium cyanide (KCN) but was inhibited by 1 m M salicylhydroxamic acid (SHAM); however, beyond this time cyanide showed increasing inhibitory effectiveness whereas SHAM became less effective. Regardless of time of application, KCN had no effect on germination. Maximum inhibition of germination by SHAM was achieved if applied up to 120 h after culture initiation, after which spores became insensitive to SHAM. Heat treatment (50°C for 90 min) during the cyanide-resistant phase of respiration (0 h–120 h) induced cyanide-sensitive respiration and completely inhibited spore germination. Elevated temperatures had little effect if applied during the cyanide-sensitive phase (beyond 120 h). Temperature inhibited spores regained their ability to germinate if maintained in culture until the cyanide-resistant pathway was restored and then subjected to a second photoinductive light treatment. These results suggest the presence and possible involvement of the cyanide-resistant, alternative respiratory pathway during germination of Sphaeropteris cooperi spores.