农田N_2O排放机制及影响因素研究

指出了土壤产生N2O主要机理是硝化和反硝化作用,土壤的物理化学性质以及农田管理措施等因素对N2O的产生和排放有显著影响。重点阐述了农田N2O的排放机制,并分析了土壤质地、pH值、温度、含水量、肥料类型、施肥方式以及作物和耕作制度等对农田土壤产生和排放N2O的影响。     

农田N_2O排放研究进展

指出了N2O作为土壤硝化及反硝化作用的中间产物,其排放受到土壤理化性状、气候因素及农田措施等因素的影响,在概述农田土壤N2O排放机制及影响因素的同时,系统总结了国内外其观测所采用的方法,并提出了相应的减排对策,以期为控制农田土壤N2O排放、发展低碳农业提供参考依据。     

降水减少对红锥和马尾松温室气体排放的影响

为了揭示降水变化对森林土壤CO2、N2O、CH4通量的影响,本研究以南亚热带红锥和马尾松人工林为研究对象,设置穿透雨减少50%和不减雨(对照),2013—2015年开展野外降水控制实验,结果表明:穿透雨减少仅导致红锥雨季土壤CO2排放通量比对照显著增加了39.1%,而对红锥全年和旱季土壤CO2排放通量、以及红锥全年、旱季和雨季土壤N2O排放和CH4吸收通量均无影响。对马尾松而言,穿透雨减少对其全年、旱季和雨季土壤CO2排放、N2O排放和CH4吸收通量的影响均不显著。另外红锥土壤温室气体排放通量大于马尾松,在减雨处理下更加明显。相关分析表明,红锥和马尾松土壤CO2排放通量与5 cm土壤温度呈指数正相关,与5 cm土壤温、湿度呈二元线性正相关;红锥和马尾松土壤N2O排放通量与5 cm土壤温、湿度的线性关系不显著;红锥土壤CH4吸收通量与5 cm土壤湿度和5 cm土壤温、湿度呈显著的线性负相关,而马尾松土壤CH4吸收通量与5 cm土壤温、湿度的线性关系不显著。总之,短期降水减少可能导致红锥雨季土壤CO2排放显著增加,然而不会改变马尾松土壤CO2、N2O和CH4通量。未来降水减少可能扩大红锥和马尾松土壤温室气体排放通量的差异。     

北京低山区两种人工林土壤中N2O排放通量的研究

N2 O是一种重要的温室气体 ,其主要的排放源是土壤。本研究采用静态封闭箱式技术在 1997～1998年对北京西山低山区元宝枫和油松人工林地土壤中N2 O的排放通量进行了原位测定。研究结果表明该地区森林土壤为大气N2 O气体的一个重要的源 ,年平均排放通量为 3 16 μg·m- 2 h- 1 ,变动范围为 - 1 2～ 7 92μg·m- 2 h- 1 。林地土壤N2 O的排放有较明显的季节变化趋势 ;夏季最高 ,春秋季次之 ,冬季最低甚至出现负值。排放通量的大小主要决定于土壤温度、土壤湿度及测定时前 5d内降水量等因子。研究还表明N2 O的排放通量有一定的日变化趋势 ;6 :0 0出现最低点 ,9:0 0和 18:0 0出现最高点     

外源氮输入下纳帕海沼泽湿地N_2O排放特征的初步研究

该文选取滇西北纳帕海沼泽湿地常见植物茭草(Zizania caduciflora)和水葱(Scirpus validus)群落湿地为研究对象,通过培养试验,研究了温度变化和植物生长与N2O排放通量的关系,及3个不同氮输入水平[0、20、40g/m2]下茭草和水葱群落湿地N2O的排放特征。结果表明:在培养过程中,适量的氮输入促进了湿地N2O的排放,但是过高的氮输入对湿地N2O的排放产生了一定的抑制作用。茭草和水葱群落湿地在各氮处理水平下的N2O排放速率随培养时间的变化显著相似(p<0.05)。茭草和水葱群落湿地在不同氮输入水平下的N2O损失量均明显高于对照,且茭草群落湿地各氮处理水平下的N2O损失量均高于水葱群落湿地。说明茭草群落湿地对氮素释放和转移能力强于水葱群落湿地。湿地N2O的排放与温度变化和植物的生物量增长都存在相关性(p<0.05)。但湿地N2O的排放受许多环境因素的综合影响,是一个复杂的过程,氮输入对N2O排放的影响机理需进一步研究。     

影响土壤N_2O排放和CH_4吸收的主控因素的研究(英文)

本文于2000年7月,在实验室模拟条件下,以长白山阔叶红松林鲜土壤为对象,采用正交试验设计法对土壤进行培养实验,研究了影响土壤N2O排放和CH4吸收的主要因素。考察了温度、水分、pH值、NH4+及NO3-五因素对森林土壤N2O排放和CH4吸收的影响。实验结果显示:在本试验设计的因素、水平条件下,N2O排放速率、CH4吸收速率二者均与土壤pH值和温度这两个因素呈显著正相关。并且N2O排放速率与CH4吸收速率间呈显著线性正相关关。     

阔叶红松林土壤CO2,N2O排放和CH4吸收的研究

为研究凋落物对CO2,N2O排放和CH4吸收的影响,从2002年9月3日到2003年10月30日,采用静态密闭箱技术对长白山阔叶红松林两种类型土壤生态系统的CO2,N2O和CH4的通量进行测定。两种土壤类型分别为表层有凋落物覆盖和没有凋落物覆盖。研究结果表明,凋落物对CO2,N2O和CH4通量有显著性影响(P<0.05)。有凋落物样地的CO2,N2O和CH4通量的日变化趋势和无凋落物样地中三种气体的日变化趋势相似,且CO2,N2O和CH4的日通量峰值都出现在18:00。有凋落物样地的CO2,N2O和CH4通量的季节变化趋势和无凋落物样地中三种气体的季节变化趋势也相似,但在一年之中,CO2和CH4的峰值出现在六月,N2O的峰值却出现在八月。研究结果还表明有凋落物样地CO2,N2O的日排放通量和年均排放通量明显大于无凋落物样地中两种气体的排放通量,但有凋落物样地的CH4日吸收通量和年均排放通量却小于无凋落物样地的CH4吸收通量。     

小兴安岭落叶松沼泽林土壤CO2,N2O和CH4的排放规律

采用静态箱-气相色谱法,研究小兴安岭兴安落叶松-油桦-修氏苔草沼泽林、兴安落叶松-油桦-笃斯越橘-藓类沼泽林和兴安落叶松-狭叶杜香-中位泥炭藓沼泽林生长季节土壤温室气体(CO2,N2O和CH4)排放通量的季节变化规律、季节排放量及其主控因素.结果表明:1)3种落叶松沼泽林土壤CO:排放通量均呈现夏季高(651.4～823.6 mg·m-2h-1)春秋季低(233.3～310.0 mg·m-2h-1)的单峰型季节变化,N2O排放通量(0.010～0.049,0.012～0.020和0.010～0.080 mg·m-2h-1)分别呈现夏季>春季>秋季,春季>夏季>秋季和秋季>春季>夏季的变化规律,CH4排放通量(-0.083～0.037,-0.122～0.078和-0.05～0.026 mg·m-2h-1)分别呈现春秋季排放、夏季吸收,春季排放、夏秋季吸收和春夏季排放、秋季吸收的交替式季节变化;2)表层土壤(0～30cm)温度是土壤CO2排放的主要影响因素,低水位与较高表层土壤温度是N2O排放的主要影响因素,水位是CH.排放的主要影响因素,高水位时土壤排放CH4,低水位时土壤吸收CH4;3)3种落叶松沼泽林土壤在生长季节均为CO2排放源(20.8～25.2 t·hm-2),且夏季为强排放源、春秋季为弱排放源,3者均为N2O排放源(0.192～1.128kg·hm-2),兴安落叶松-油桦-修氏苔草沼泽林为强排放源,另2者为弱排放源,兴安落叶松-油桦-修氏苔草沼泽林和兴安落叶松-油桦-笃斯越橘-藓类沼泽林土壤为CH4强吸收汇(1.152～1.200 kg·hm-2),兴安落叶松-狭叶杜香-中位泥炭藓沼泽林土壤为CH4弱排放源(0.168 kg·hm-2);4)兴安落叶松-油桦-修氏苔草沼泽林土壤温室气体CO2排放强度最高(25.4 t·hm-2),另2者相对较低(20.8～21.2 t·hm-2),但均以CO2排放占绝对优势地位(99.63%～99.93%),N2O和CH4排放占次要地位(0.19%～0.92%和0.02%～0.10%).     

排水造林对泥炭沼泽湿地碳循环的影响

湿地在全球气候变化中扮演着重要作用,当湿地排水后,地表水位下降,湿地土壤有氧层增加,CO2排放速率增加,CH4排放速率减少,进而影响全球温室气体的浓度。本文综述了国内外有关湿地排水对土壤CO2、CH4、N2O温室气体和土壤碳储量影响的研究进展,指出了应加强研究的方向,可为湿地恢复和碳管理的研究提供参考。     

‘灿烂’蓝莓测土配方施肥研究

蓝莓对土壤pH值的特殊要求以及对部分肥料的敏感,限制了某些肥料在生产中的使用,为了探讨氮、磷、钾在蓝莓生长发育过程中的作用和影响,以8年生的‘灿烂’(Brightwell)为材料,采用“3414”进行施肥处理,结果表明:配方施肥能有效提高土壤中的水解氮、有效磷、速效钾含量;施用酸性肥料,可以降低土壤pH值;最佳施肥组合(N∶P∶K)配比是2∶1∶1,施肥方案为:N20~24g/株,P2O510~12g/株,K2O10~12g/株(折合N80~96kg/hm2,P2O540~48kg/hm^2,K2O40~48kg/hm2)。     

Effects of soil moisture and temperature on CH4 oxidation and N2O emission of forest soil

IntroductionMethane (CH4) and Nitrous oxide (NZO) are tWoimportant greenhouse gases that also play an important role in photochemical reactions in atmosphere.The global warming potential of CH4 and NZO areestimated tO be about 62 and 290 times that of carbon dioxide respeCtively. The concentration of thesegases have been increasing rapidly since the start ofthe industrial age, currently at rate of about 1% and0.25% per year respeCtively (Lelieveld et al. 1993),and 70%-90% of these gases …     

蓝桉造林施肥对林地土壤肥力影响的监测结果

为了解蓝桉人工林地土壤肥力的变化情况，进行了蓝桉施肥和造林后的林地土壤肥力监测和分析。经对设于保山市辛街３种施肥处理的蓝桉人工林地，进行为期两年（１９９３、１９９４年）的土壤１１项化学性状监测得出：土壤的有效Ｎ、Ｐ、Ｋ的含量随林地的施肥而增加；造林两年后，土壤的ｐＨ（Ｈ２Ｏ）、ｐＨ（ＫＣｌ），有机酸，全氮，有效Ｎ、Ｐ、Ｋ，水解酸，交换性Ｃａ（＋＋）、Ｍｇ（＋＋）的指标均低于造林前。     

An alternative modelling approach to predict emissions of N<Subscript>2</Subscript>O and NO from forest soils

Emissions of N₂O from forest soils in Europe are an important source of global greenhouse gas emissions. However, influencing the emission rates by forest management is difficult because the relations and feedbacks between forest and soils are complex. Process-based models covering both vegetation and soil biogeochemical processes are frequently used to analyse emission patterns. Particularly, the simulation of soil C and N turnover processes driving N₂O production, consumption and emission from forest soils requires highly specific input data which renders their regional application difficult since at this scale, soil conditions are often not well understood. Therefore, a soil C and N model (DecoNit) has been developed which describes biogeochemical processes with a simplified structure compared to existing carbon/nitrogen models that nevertheless follows the basic physical and chemical laws involved and which allows to simulate N trace gas emissions. The DecoNit model was previously calibrated using an extensive dataset on decomposition rates of incubated plant materials, microbial dynamics and nitrification. The DecoNit model has now been embedded in a modular simulation environment (MoBiLE) where it is combined with soil water balance and forest process sub-modules. Here, we present the evaluation of MoBiLE-DecoNit with emission data of N₂O and NO from forest soils of 15 European sites and compare simulation results with a previous study in which a more complex model (PnET-N-DNDC) was used. Evaluation criteria were as follows: (1) precision of modelled annual average emission rates; (2) coherence of modelled and measured annual average and daily emissions; (3) a dynamic representation of emission rates that correspond with the observed variance of fluxes. The results show that MoBiLE-DecoNit captures average annual emission rates more precisely than the more complex model PnET-N-DNDC. Also the structural underestimation of N trace gas fluxes from forest soils was resolved. Moreover, we present evidence that the new modelling approach is also somewhat more adequate for describing inter-daily emission dynamics. The combined MoBiLE-DecoNit is therefore thought to be a promising approach to simulate forest development and greenhouse gas balances on site and regional scales.     

土壤水分胁迫对树木N2O排放速率的影响

采用封闭罩-气相色谱法观测研究了干旱胁迫对长白山阔叶红松林的几种优势树种-红松(Pinus koraiensis)、水曲柳(Fraxinus mandshurica)、胡桃楸(Juglans mandshurica)、椴树(Tilia amurensis)和蒙古栎(Quercus mongolica)叶片N2O排放。并同步测定5种树木叶片净光合速率、呼吸速率和气孔导度。结果表明：土壤水分胁迫明显降低树木叶片气孔导度、净光合速率和N2O排放速率，叶片气孔是树木N2O排放的主要通道。树木N2O排放以白天为主，在相同的水分条件下，不同的苗木有不同的N2O排放速率，同种苗木的N2O排放随干旱胁迫的加重而减少，在受到不同干旱胁迫时，针叶树红松N2O的排放速率降至正常水分条件下的34.43％和100．6％、阔叶树种N2O排放平均降至31．93％和86.35％。不同干旱胁迫的红松、水曲柳、胡逃楸、椴树和蒙古栎幼树叶片N2O排放速率为34．43、14．44、33．02、16.48和32．33ngN2O．g^-1DW．h^-1。图1表1参12。     

Factors controlling N_2O and CH_4 fluxes in mixed broad-leaved/Korean pine forest of Changbai Mountain, China

IntroductionTheincreasinggreenhousegasconcentrationshavereceivedmuchattention.TwoofthesegasesthatscientistsareveryconcernedaboutareN2oandCH`,becauseoftheirrapidincreaseandtheirim-portantchemistryintheatmosphere(Bouwman199o).ThemoIecuIegIobalwarmingpotentialofN2OandCH4areabout58and2o6timesthanthatofCO2.Inaddition,atmosphericconcentrationsofN2OandCH`areincreasingatahnualratesofo.25%ando.9%respectively(HoughtonetaI1992).Forestecosystemhasbeenknownasanimportantterres-trialecosystemattheasp…     

氮沉降对森林土壤碳动态过程的影响

本文综述了国内外关于森林土壤碳动态过程对氮沉降响应机制的研究进展,概述了大气氮沉降对土壤碳释放及其影响因子的作用机制,从土壤生物学特性、凋落物动态、土壤碳释放等方面揭示大气氮沉降对土壤碳平衡过程影响机制和机理,探讨了森林土壤碳动态过程对氮沉降响应的不确定性因素,并指出未来该领域研究重点。     

磷添加对南亚热带森林土壤有机碳氮矿化影响的培养实验研究

采用室内培养的方法,分析了磷添加对南亚热带鼎湖山马尾松林（PMF）、针阔叶混交林（PBMF）和季风常绿阔叶林（MEBF）土壤（0～10cm）CO小CH4排放／吸收和有机氮矿化的影响。结果表明：28周的培养,100mg磷添加处理土壤C—CO2累积排放量依次为PMF、PBMF和MEBF对照的82．4％、84．4％和102．8％,2000mg磷处理土壤依次为其对照的107．2％、101．2％和109．1％;100mg磷处理土壤CH4累积排放量依次为其对照的69．9％、102．7％和66．3％,2000mg磷处理土壤依次为其对照的-57．4％、25．3％和22．4％,其中,磷在处理初期较一致的提高土壤CO2和CH4排放,磷对土壤有机碳矿化的影响与森林的土壤状况有关,添加的磷浓度越高,其促进作用越强。1周的培养,100mg磷处理土壤有效氮净矿化量依次比PMF、PBMF和MEBF对照少37．06％、39．60％和28．62％,2000mg磷处理土壤依次比其对照少70．97％、84．14％和187．97％,100mg磷处理土壤硝态氮净矿化量依次比其对照少48．06％、40．45％和28．03％,2000mg磷处理土壤依次比其对照少254．09％、115．32％和238．50％,磷显著的抑制土壤有机氮的矿化和硝化。结果建议,在研究P对土壤有机碳氮矿化过程时应充分考虑土壤对P的吸附作用。     

森林土壤酶活性对氮沉降的响应

近年来,大气氮沉降日益增加,已对森林生态系统产生了不可忽视的影响,而土壤酶活性反映了土壤肥力及土壤环境质量,因而可以用来评价氮沉降对森林土壤造成的影响。关于氮沉降对森林生态系统酶活性的影响已开展了一系列的研究,然而尚缺少系统总结。文中从森林土壤酶种类和林分类型角度总结了氮沉降对土壤酶活性的影响,并从氮沉降水平、氮种类形态、氮沉降与环境的交互作用等方面探讨了土壤酶活性对氮沉降的响应机制,提出未来研究热点是氮沉降对不同类型的森林土壤酶影响、不同森林类型土壤酶的氮沉降临界值、氮沉降对土壤酶活性影响的长期定位研究以及氮沉降与CO₂浓度、温度、降雨、磷添加的交互作用对土壤酶活性影响,以期为未来森林土壤管理提供参考。     

Short-term effects of nitrogen deposition on soil respiration components in two alpine coniferous forests,southeastern Tibetan Plateau

Nitrogen (N) deposition to alpine forest ecosystems is increasing gradually, yet previous studies have seldom reported the effects of N inputs on soil CO2 flux in these ecosystems. Evaluating the effects of soil respiration on N addition is of great significance for understanding soil carbon (C) budgets along N gradients in forest ecosystems. In this study, four levels of N (0, 50, 100, 150 kg N ha^-1 a^-1) were added to soil in a Picea baifouriana and an Abies georgei natural forest on the Tibetan Plateau to investigate the effect of the N inputs on soil respiration. N addition stimulated total soil respiration (Rt) and its components including heterotrophic respiration (Rh) and autotrophic respiration (Ra);however, the promoted effects declined with an increase in N application in two coniferous forests. Soil respiration rate was a little greater in the spruce forest (1.05 μmol CO2 m^-2 s^-1) than that in the fir forest (0.97 μmol CO2 m^-2 s^-1). A repeated measures ANOVA indicated that N fertilization had significant effects on Rt and its components in the spruce forest and Rt in the fir forest, but had no obvious effect on Rh or Ra in the fir forest. Rt and its components had significant exponential relationships with soil temperature in both forests. N addition also increased temperature sensitivity (Q10) of Rt and its components in the two coniferous forests, but the promotion declined as N in put increased. Important, soil moisture had great effects on Rt and its components in the spruce forest (P<0.05), but no obvious impacts were observed in the fir forest (P>0.05). Following N fertilization, Ra was significantly and positively related to fine root biomass, while Rh was related to soil enzymatic activities in both forests. The mechanisms underlying the effect of simulated N deposition on soil respiration and its components in this study may help in forecasting C cycling in alpine forests under future levels of reactive N deposition.