木麻黄人工林土壤呼吸测定方法的比较分析

以惠安滨海沙地木麻黄沿海防护林为研究对象,采用静态箱式法和LI-8100Automated Soilk CO2 Flux System 两种方法测定比较了木麻黄人工林土壤呼吸的日动态和季节动态.分析表明,静态法的测定结果是动态法的1.327倍,且测定结果不太稳定.两种方法的线性回归分析得出R2=0.8258,说明它们存在显著的线性关系,这两种方法的测定结果都有较高的可信度.     

亚热带常绿阔叶林根系呼吸及其与环境影响因子的关系

采用切断根系法,运用Li-6400光合呼吸测定仪对肖坑亚热带常绿阔叶林根系呼吸特性及其对土壤呼吸的贡献和季节动态变化进行了研究,并探讨了根系呼吸对土壤温度和含水量的响应。结果表明,中龄林根系呼吸速率年变化范围为0．412～1．970μmol／（M^2·s）,幼龄林为0．259—1．414μmol／（m^2·s）;幼龄林年平均根系呼吸速率（1．198μmolf（M^2·s））是中龄林的（0．937μmol／（m^2·s））1．13倍。中龄林和幼龄林根系呼吸速率及根系呼吸占土壤总呼吸的比例季节变化规律基本一致,1年中基本呈单峰曲线模式,高峰值出现在6月,之后逐渐下降至次年1月达最低值。幼龄林根系呼吸占土壤总呼吸的比例为31．79％～59．00％;而中龄林根系呼吸所占比例范围（23．50％-50．26％）较幼龄林小。中龄林和幼龄林根系呼吸速率与土壤5cm内温度相关性显著。中龄林根系呼吸对土壤温度的敏感程度大于幼龄林。在温度较低的情况下,土壤高含水量并没有促进根系的呼吸,但与土壤温度互作可能对林木根系呼吸产生较为显著的促进效果,这方面还需进一步研究。     

巨桉根系和根系土壤化感物质的研究

研究了以正己烷作溶剂,用超声浸提巨桉根系及其根系土壤,并用GC—MS检测其成分．用该法鉴定出根系含有烷烃、烯烃、芳香烃、醇、醛、酮、蒽醌、芳香酸酯、含N的萘杂环等9类29种有机成分;根系土壤含有烷烃、烯烃、芳香烃、醇、芳香酸酯、烯酸酯、内酯、氰等8类22种有机成分．证明了根系及其土壤中存在化感物质,表明了化感作用研究有一定的价值;根系和根系土壤中有17个相同化学成分,可推测土壤的这些化感成分可能来自巨桉的根系分泌物,但其作用机理有待进一步研究．     

复垦土壤气热条件对薄荷生长与根系呼吸的影响

为探究矿区煤矸石充填复垦土壤内部C、S等物质缓慢氧化产生的二氧化碳及热量对表土植物的影响,应用实验室模拟试验,分析复垦土壤底部加热与通CO_2气体对薄荷生长特征与根系呼吸的影响。试验底部加热温度分别设置为20℃、40℃、60℃,通气通量分别为1L/min、2L/min和3L/min,各梯度通气时间设置5min、10min。结果表明:不同程度通气对薄荷生理特征和根系呼吸的影响不同。底部通气5min/d时,随着通气浓度的增大,薄荷地上、地下生物量以及根系呼吸速率均呈上升趋势,叶面积指数呈先增后减趋势;底部通气10min/d时,叶面积指数呈下降趋势,地上、地下生物量以及根系呼吸速率均呈先增后减趋势。综合对比通气10min/d与5min/d,根系生物量与根系呼吸速率均有下降,下降率分别为17%、8%,叶面积指数与地上生物量略有增加,增长率分别为1%、9%;随着煤矸石底部加热温度由20℃升高至40℃,再升高至60℃的过程中,薄荷的叶面积指数、地上与地下生物量以及根系呼吸速率均表现出先上升后下降的趋势,在40℃时达到最大值。     

土壤呼吸对温度的敏感性研究综述

土壤呼吸对温度变化的响应已成为生态学研究的重要内容之一。根据近年来国内外最新的研究资料,综合介绍了土壤呼吸对温度敏感性方面的研究现状与成果,分析和探讨存在的问题。温度是影响土壤呼吸的重要因子,土壤呼吸与温度之间相关关系密切,但土壤呼吸对温度变化的响应与机制仍不确定。模拟土壤呼吸对温度的敏感性模型有多种且在不断完善,但简单的Q10经验模型仍被普遍使用。土壤呼吸各来源对温度的敏感性贡献仍不明确。因此在今后的研究中,应规范统一土壤呼吸和温度的测定方法,明确各因子对土壤呼吸的影响,土壤呼吸的时空异质性,土壤呼吸各组分对土壤呼吸的贡献以及各组分对温度的敏感性。     

黄土区直根系作物地土壤分离生长季动态*

目的为黄土高原土壤侵蚀控制提供科学依据。方法运用变坡试验水槽的实验方法,研究了黄土高原地区典型直根系作物大豆和马铃薯在生长季土壤分离过程的季节变化及潜在影响因素。结果 1在作物生长季,直根系作物大豆地和马铃薯地的土壤分离能力具有明显的季节变化(P0.05),并表现出了相似的季节变化模式;2两种作物地土壤分离能力的季节变化主要受到农事活动、土壤硬化、水稳性团聚体和作物根系生长的影响;3两种作物地土壤分离能力的季节变化可以用水流剪切力、土壤粘结力和作物根系密度很好地模拟(R20.64,NSE0.63)。结论黄土区直根系作物地土壤分离过程具有明显季节变化,该变化主要是由农事活动、土壤粘结力和作物根系密度季节变化影响所致。     

土壤中有机质含量测定方法研究

通过对土壤中有机质含量测定方法要点消解温度、消解时间、试液酸度的研究,得出在测定土壤中有机质含量时,试样消解温度、试样消解时间、试样消解酸度对试样测定结果影响较大,影响顺序为试样消解温度试样消解时间试样消解酸度;若消解温度控制在170～180℃、试样酸度约为9.2 mol/L、消解时间≥5 min时,试样中的有机碳将全部被氧化,测定结果稳定可靠.     

土壤中邻苯二甲酸酯的净化分离方法研究

确定了土壤中邻苯二甲酸酯的高效液相色谱分析方法。用石油醚／丙酮（Ｖ／Ｖ∶３／１）超声萃取土壤样品，微型硅胶柱净化预分离，浓硫酸纯化，最后用高效液相色谱紫外检测器检测土壤中的邻苯二甲酸酯，土壤中邻苯二甲酸酯的添加回收率在８８５％～１０５０％之间，检测极限在８～１３ｎｇ／ｇ之间     

薇甘菊入侵对土壤微生物生物量和土壤呼吸的影响

在野外实验样地中选取了薇甘菊入侵程度不同的4个样地,测定了土壤理化因子、土壤微生物生物量(C、N、P)以及土壤基础呼吸和基质诱导呼吸等指标的变化.结果表明,薇甘菊入侵后土壤微生物生物量(C、N、P)显著增加,土壤呼吸加快,土壤代谢熵(qCO2)下降,改善了入侵地土壤的养分供应状况,这可能是薇甘菊入侵成功的一个重要原因.     

不同林龄木麻黄人工林的土壤呼吸比较分析

以惠安县木麻黄沿海防护林作为研究对象,对不同林龄木麻黄纯林进行土壤呼吸比较研究.结果表明:总呼吸速率大小相近,在2.62-4.02μmolm-2·s-1左右:五个样地的异养呼吸速率平均值分别为2.05、2.70、2.90、2.01和2.20μmolm-2·d-1,幼林和中林的异养呼吸略大于成熟林,土壤异养呼吸在不同林龄之间差异不显著.     

The contribution of root respiration to soil CO2 efflux in Puccinellia tenuiflora dominated community in a semi-arid meadow steppe

Rising atmospheric CO2 and temperature are altering ecosystem carbon cycling. Grasslands play an important role in regional climate change and global carbon cycle. Below-ground processes play a key role in the grassland carbon cycle because they regulate …     

A new estimate of global soil respiration from 1970 to 2008

Soil respiration(Rs)is one of the key processes that underline our understanding of carbon cycle in terrestrial ecosystems.Great uncertainty remains in the previous global Rs estimates with a difference of 70 Pg C a 1between the highest and lowest estimates.Thus,the present study aimed to estimate the global annual Rs and investigate the interannual and spatial variability in global annual Rs using a semi-mechanistic,empirically-based model which included climatic factors(temperature and precipitation)and topsoil(0–20 cm)organic carbon storage.About 657 published studies of annual Rs from 147 measurement sites were included in this meta-analysis.The global data sets from 1970 to 2008 on climate,surface air temperature,and soil properties were collected.The Monte Carlo method was used to propagate the simulation errors to global Rs.The results indicated that the mean annual global Rs was 94.4 Pg C a 1,increasing at roughly 0.04 Pg C a 1(~0.04%a 1)from 1970 to 2008.The Rs rate increased from colder,drier and less soil carbon-rich regions to warmer,moister and more carbon-rich regions.Highest Rs rates appeared in the tropical forest,while the lowest ones were in polar and desert regions.The annual Rs correlated directly with global temperature anomalies,suggesting that the interannual variability in temperature was responsible for the interannual variations in predicted global Rs.The global Rs increased from high-latitude zones to low-latitude zones.Further studies are recommended to explore the relationship between soil respiration and vegetation characters.     

Quantifying tidal contribution to submarine groundwater discharges: A review

Submarine groundwater discharges (SGD), consisting of groundwater flow from both terrestrial and marine origins, is an important source of nutrients, contaminants, and other chemicals to the coastal waters, and has significant impacts and implications on coastal environment and ecology. This paper reviews the recent advances in quantifying the tide-induced SGD in various beach aquifers around the world by means of mathematical modeling, laboratory experiments, and field observations or their combinations. Numerous studies have shown that (1) the order of magnitude of SGD around the world estimated by radium isotope tracers typically ranges from 102 to 103m3d-1m-1 of the shoreline, (2) SGD is mainly of marine origin, i.e. the re-circulated seawater across the aquifer-sea interface, and (3) tide is one of the major forces driving seawater-groundwater circulation. The order of magnitude of the tidal contributions to SGD from beach aquifers reported in the literature is only 10m3d-1m-1 length of shoreline, at least one order of magnitude smaller than the total SGD estimated by radium isotope tracers. This is obviously in contradiction with (3). The possible reasons for this contradiction may include (1) underestimation of the shoreline length due to neglecting many headlands, bays and banks of tidal rivers, and (2) negligence of the seawater-groundwater exchange from the seabed ranging from the nearshore areas to the continental shelf. Further research is needed to understand more about the contradiction.     

Overestimation of global soil heterotrophic respiration

Soil heterotrophic respiration (Rh) is the flux of CO2 that microbes and soil fauna release to the atmosphere by extracting the energy of organic molecules that...     

蚯蚓活动对高羊茅修复土壤芘污染的强化作用

为了探讨土壤动物在植物修复多环芳烃类有机污染物过程中的作用,采用盆栽试验法,对比研究了蚯蚓(Pheretimasp.)活动对高羊茅(Festuca arundinacea)修复土壤芘污染的影响效应.在72d的试验期间,蚯蚓活动促进了芘污染土壤(20.24～321.42mg.kg-1)中高羊茅的生长,其根冠比明显增大.试验结束时,种植高羊茅的土壤中芘的去除率高达55.89%～82.01%,其平均去除率(69.91%)比无蚯蚓活动的土壤-植物(高羊茅)系统(60.06%)提高9.85%,比无植物对照组(18.24%)提高50.67%.各种生物、非生物修复因子中,植物-微生物交互作用(plant-icrobial interaction)对芘去除的贡献率(44.08%)最为突出,比无蚯蚓活动时(37.54%)提高6.53%.说明蚯蚓活动可强化土壤-植物系统对土壤芘污染的修复作用.     

UV-B和NO对玉米幼苗根系呼吸作用的影响

通过对玉米幼苗根系生物量、NO释放量、呼吸作用的分析测定,发现UV-B辐射能够促进根系生物量,却明显地抑制玉米幼苗根系NO的释放、交替呼吸途径活性和细胞色素呼吸途径活性,因而降低了根系的总呼吸量.NO尽管对交替呼吸运行量有抑制作用,但能够明显地促进玉米幼苗根系交替呼吸容量、细胞色素呼吸途径的呼吸容量和运行量以及总呼吸,这可能与玉米幼苗根系相对缺氧时,与根系组织中植物球蛋白协同NO对活性氧(ROS)的生成、清除和转化以及刺激通气组织的形成、供氧条件的改善有关.     

西双版纳热带森林碳循环中土壤呼吸对次生演替的响应

【目的】探明热带森林次生演替过程中土壤呼吸速率的季节变化及其主要调控因素,分析土壤微生物生物量碳及理化性质对土壤呼吸速率时间动态的影响,为精确评估热带森林恢复对土壤碳库变化的影响提供参考。【方法】采用LI-6400-09便携式土壤呼吸测定仪对西双版纳热带森林演替前期的白背桐(Mallotus paniculatus)群落与演替后期的高檐蒲桃(Syzygium oblatum)群落土壤呼吸速率进行连续定位观测,结合相关分析和主成分分析,探讨热带森林演替过程中土壤微生物生物量碳、容重、pH及碳氮库各组分含量变化对土壤呼吸速率的影响。【结果】研究区白背桐与高檐蒲桃群落土壤呼吸具有明显的单峰型季节变化特征,最大值出现在湿季(6月),其中高檐蒲桃群落土壤呼吸速率[3.80~6.19 μmol/(m²·s)]显著高于白背桐群落[2.40~4.35 μmol/(m²·s)],但恢复前期土壤呼吸变幅(1.81倍)显著高于恢复后期(1.63倍);土壤呼吸速率随土壤温度和水分季节变化呈非线性显著或极显著增加的趋势(P<0.01或P<0.05),其中,高檐蒲桃群落温度、水分对土壤呼吸的解释率分别为49.00%~65.30%、2.96%~53.00%,显著高于白背桐群落的6.40%~49.10%、2.48%~43.70%;两群落土壤呼吸速率均与碳库(总碳、土壤微生物生物量碳)及氮库(硝态氮、全氮、铵态氮)含量显著或极显著正相关(P<0.01或0.05),并与pH呈极显著负相关 (P<0.01);土壤易氧化碳、硝态氮、含水量对土壤呼吸变化的贡献最大,而土壤温度、土壤微生物生物量碳、全氮、铵态氮及水解氮的影响次之。【结论】西双版纳热带森林次生演替显著促进了土壤呼吸,土壤呼吸时间动态主要受土壤微气候(如含水量)及土壤碳库(如易氧化碳)、氮库(如硝态氮)组分含量所调控。     

Experimental study on soil respiration of temperate grassland in China

Understanding of CO2 source and sink characteristics of terrestrial ecosystem is one of the most critical prob-lems at present, but till now, most studies concerning the natural terrestrial ecosystem carbon cycle are concentrated on the forest ecosystem. Not enough attention is paid to the natural grassland, especially to the temperate natural grassland, whose area is almost equal to that of tropical forest in the world. Little is known about the role of the grassland, which takes about 25% of…     

Acclimatization of soil respiration to warming in a tall grass prairie.

The latest report by the Intergovernmental Panel on Climate Change (IPCC) predicts a 1.4-5.8 degrees C average increase in the global surface temperature over the period 1990 to 2100 (ref. 1). These estimates of future warming are greater than earlier projections, which is partly due to incorporation of a positive feedback. This feedback results from further release of greenhouse gases from terrestrial ecosystems in response to climatic warming. The feedback mechanism is usually based on the assumption that observed sensitivity of soil respiration to temperature under current climate conditions would hold in a warmer climate. However, this assumption has not been carefully examined. We have therefore conducted an experiment in a tall grass prairie ecosystem in the US Great Plains to study the response of soil respiration (the sum of root and heterotrophic respiration) to artificial warming of about 2 degrees C. Our observations indicate that the temperature sensitivity of soil respiration decreases--or acclimatizes--under warming and that the acclimatization is greater at high temperatures. This acclimatization of soil respiration to warming may therefore weaken the positive feedback between the terrestrial carbon cycle and climate.