Impact of human activities on soil respiration: A review

Soil respiration is one of the primary fluxes of carbon between soils and the atmosphere.It is produced by rhizosphere respiration and soil microbial respiration.Soil respiration is not only affected by environmental factors,but also changes with the hu-man-induced disturbances of ecosystems.Land-use,the measures of land management,the pollution of soil,and so on can affect soil respiration and change the soil efflux.According to some research,the authors summed up their impacts on soil respiration by human activities through land-use changes and land-management measures among agroecosystem,grassland ecosystem,and for-est ecosystem.The results showed that (1) when adding fertilization to farmland,the soil respiration will increase;(2) fenced land can decrease soil respiration,while soil respiration in the grazed land at a grassland ecosystem will decline with the increasing of grazing intensity;(3) with grassland fertilization;farmland cultivation;fire,fertilization,and cutting of forest,conflicting results were found in the changes of soil respiration.Perhaps plant species,site condition,and measurement season can lead to different results on soil respiration.     

碳同位素在草地生态系统碳循环中的应用与展望

草地生态系统在全球碳循环研究中占有重要地位,目前,碳同位素技术已经被广泛地应用于草地生态系统碳循环研究中。本文阐述了碳同位素在草地土壤有机碳的来源、光合作用产物碳在草地生态系统中的分配、草地土壤有机质的周转及草地土壤呼吸研究方面的应用,重点论述了碳同位素在土壤呼吸方面的应用。应用碳同位素对土壤呼吸进行区分的方法主要包括13C自然丰度法、脉冲标记法、同位素稀释法、模拟根际沉积物法、14CO2动态模型法、根系分泌物洗涤法等。碳同位素技术对草地土壤和根干扰很小,方法相对成熟,为深入研究草地生态系统碳循环提供了巨大潜力。在我国,应用碳同位素方法研究草地生态系统碳循环在土壤有机碳的来源、分配及周转和土壤呼吸区分等方面有进一步研究的必要,也有进一步研究的发展空间。     

沙漠人工植被区土壤呼吸初探

2003年9月底,在沙坡头铁路北面的1956年、1964年、1981年和1987年始植的人工植被区和流动沙丘的迎风坡,分别在阴天、晴天和雨后用CI301SR测定土壤呼吸速率,结果表明:土壤呼吸速率在各样地间、日期间和互作均达到极显著水平;尤其是雨后样地间的差异非常明显。1956年始植、1964年始植、1981年始植、1987年始植样地和流沙不同天气状况下的平均土壤呼吸速率分别为-0.1537μmol·s^-1·m^-2、-0.0995μmol·s^-1·m^-2、-0.0583μmol·s^-1·m^-2、-0.0754μmol·s^-1·m^-2和-0.0336μmol·s^-1·m^-2;阴天、晴天和雨后不同样地的平均土壤呼吸速率分别为-0.0342μmol·s^-1·m^-2、-0.0778μmol·s^-1·m^-2和-0.1403μmol·s^-1·m^-2。在沙漠人工植被区,影响土壤呼吸的主要因子是水分,其次是温度与植物群落类型和发育阶段。     

镉对石莼光合作用和呼吸作用及叶绿素含量的影响

实验表明 ,用含不同浓度镉 (0、5、10、15、2 0、2 5、30× 10 -6)的海水培养石莼 1～ 8d,石莼的光合作用、呼吸作用、叶绿素含量受到了明显的影响。 5× 10 -6的镉培养 3d,光合速率和叶绿素含量明显下降 ;培养时间越长 ,下降幅度越大。低浓度的镉 (5～ 10× 10 -6)对呼吸有促进作用 ,出现了“伤呼吸”;高浓度的镉 (>10× 10 -6)对呼吸有明显抑制作用 ,培养 5d后石莼开始死亡。     

陆面模式中土壤呼吸的研究概况

土壤呼吸是陆地植被吸收的CO2返回大气的基本途径,土壤呼吸速度轻微变化也会引起大气中CO2浓度的明显改变,进而影响气候变化。陆面过程模式中更好地描述土壤呼吸过程对于预测未来气候变化是至关重要的。对于土壤呼吸的模拟研究,介绍了经验模型和以过程为基础的机理模型,以及国内外陆面过程模式中土壤呼吸的研究情况,并讨论了土壤呼吸模式中需要改进的问题。       

阿塔卡马海沟表层水颗粒有机碳与微生物群落呼吸作用的时空变化研究

海沟是全球大洋体系的重要组成部分。研究这一极端环境的生物地球化学循环过程有助于我们进一步理解海洋的物质循环。前期研究发现,海沟表层水体的初级生产力(NPP)对海沟沉积物埋藏的有机碳性质具有重要影响,但是,颗粒有机碳(POC)在沉降过程中被微生物呼吸和降解的过程尚不清楚。因此,本研究利用2018年春"太阳号"阿塔卡马海沟(Atacama Trench)国际联合航次SO261所采集的表层水样品,测试其中POC浓度、C/N、δ¹³C、δ¹⁵N等参数,并结合0.2—0.8、0.8—3.0、>3.0μm三种粒径微生物群落呼吸(microbial community respiration,MCR)速率测试,探究其日变化模式及不同站位的空间变化模式,进而衡量微生物对POC的呼吸降解作用。结果表明,该海域表层水中对POC降解占主导作用的微生物类群粒径为0.8—3.0μm;24 h时间序列实验表明MCR随时间呈现"M"型曲线的双峰变化模式,且和C/N、δ¹³C、δ¹⁵N等参数变化趋势吻合,表明同一站位的呼吸速...     

青岛奥帆基地海域漂浮浒苔光合生理特点研究

研究了青岛奥帆基地海域漂浮浒苔Enteromorpha prolifera （Muell）J.Ag.色素组成及含量、光合放氧及呼吸耗氧速率、P／R（净光合放氧速率／净呼吸耗氧速率）、抗氰呼吸等各项生理指标。结果表明,该海域漂浮浒苔的各项生理指标都在正常范围内,且有抗氰呼吸的存在,生长状况良好。     

Diurnal Variations of Hydrochemistry in a Travertine-depositing Stream at Baishuitai, Yunnan, SW China

Diurnal variations of hydrochemistry were monitored at a spring and two pools in a travertine-depositing stream at Baishuitai, Yunnan, SW China. Water temperature, pH and specific conductivity were measured in intervals of 5 and 30 min for periods of 1 to 2 days. From these data the concentrations of Ca²⁺, HCO₃⁻, calcite saturation index, and CO₂ partial pressure were derived. The measurements in the spring of the stream did not show any diurnal variations in the chemical composition of the water. Diurnal variations, however, were observed in the water of the two travertine pools downstream. In one of them, a rise in temperature (thus more CO₂ degassing) during day time and consumption of CO₂ due to photosynthesis of submerged aquatic plants accelerated deposition of calcite, whereas in the other pool, where aquatic plants flourished and grew out of the water (so photosynthesis was taking place in the atmosphere), the authors suggest that temperature-dependent root respiration underwater took place, which dominated until noon. Consequently, due to the release of CO₂ by the root respiration into water, which dominated CO₂ production by degassing induced by temperature increase, the increased dissolution of calcite was observed. This is the first time anywhere at least in China that the effect of root respiration on diurnal hydrochemical variations has been observed. The finding has implications for sampling strategy within travertine-depositing streams and other similar environments with stagnant water bodies such as estuaries, lakes, reservoirs, pools and wetlands, where aquatic plants may flourish and grow out of water.     

三江平原典型土地利用类型土壤呼吸强度 对温度的敏感性

采用实验室恒温培养方法对三江平原3种不同土地利用类型开发后的沼泽土和草甸土进行了温度敏感性研究。研究结果表明,在5℃、15℃、25℃和35℃ 4种不同温度条件下,各土壤类型的土壤呼吸速率均随温度的升高而增大。在同一温度条件下,3种土壤呼吸强度由弱到强依次是：草甸土-旱地<草甸土-水田<沼泽土-人工林。指数模型和乘幂模型均可以较好地描述沼泽土和草甸土土壤呼吸与温度之间的关系,土壤呼吸强度随温度的升高呈指数或乘幂上升。3种土壤的Q10值呈现出随温度升高而降低的趋势,表明土壤呼吸在较低温度下的温度敏感性更高。对未添加植物残体的纯土壤组和添加了植物残体的对照组进行对比研究,发现添加植物残体后土壤呼吸强度大大增强,因此野外实际的土壤呼吸强度要比通常室内实验中去除植物残体后所测定的土壤呼吸强度更高。