2001-2015年青藏高原草地碳源/汇时空变化及其与气候因子的关系     

周夏飞  於方  曹国志  杨威杉  周颖 《水土保持研究》2019,(1):76-81

净生态系统生产力(NEP)是估算区域植被碳源/汇的重要指标。以青藏高原为研究区,基于光能利用率模型,利用遥感数据、气象数据和基础地理数据测算了2001—2015年草地生态系统净初级生产力(NPP),同时,应用土壤呼吸模型估算了逐月平均土壤呼吸量(Rs),进而估算青藏高原草地净生态系统生产力(NEP)。研究揭示了2001—2015年青藏高原草地生态系统NPP,NEP时空格局及其与气候因子的关系。结果表明:(1)2001—2015年,青藏高原草地生态系统整体表现为碳汇,平均净碳汇总量为1.82×1014 gC/a;(2)2001—2015年青藏高原草地生态系统NEP呈波动增加趋势,年平均值为120.8gC/(m2·a),年平均增长率为0.7gC/(m2·a);(3)研究区草地NPP与温度、降水相关性不显著,NEP与降水、温度均呈负相关。  相似文献   

小麦-玉米-大豆轮作下黑土农田土壤呼吸与碳平衡   总被引：6，自引：1，他引：5  

梁尧  韩晓增  乔云发  李禄军  尤孟阳 《中国生态农业学报》2012,20(4):395-401

农田生态系统是陆地生态系统的重要组成部分,探讨农田生态系统的土壤呼吸与碳平衡对于科学评价陆地生态系统在全球变化下的源汇效应具有重要意义。基于中国科学院海伦农业生态实验站的长期定位试验,对不同施肥处理下黑土小麦-玉米-大豆轮作体系2005—2007年的作物固碳量与土壤CO2排放通量进行了观测,并对该轮作体系下黑土农田生态系统的碳平衡状况进行了估算。结果表明:在小麦-玉米-大豆轮作体系中,作物固碳量的高低表现为:玉米>大豆>小麦,平均值分别为6 513 kg(C).hm-2、4 025 kg(C).hm-2和3 655kg(C).hm-2。从作物生长季土壤CO2排放总量来看,3种作物以大豆农田生态系统的土壤CO2排放总量最高,平均值达4 062 kg(C).hm-2;其次为玉米,为3 813 kg(C).hm-2;而小麦最低,为2 326 kg(C).hm-2。3种作物轮作下NEP(净生态系统生产力)均为正值,表明黑土农田土壤-作物系统为大气CO2的"汇",不同作物系统的碳汇强度表现为玉米>小麦>大豆,三者的平均值分别为3 215 kg(C).hm-2、1 643 kg(C).hm-2和512 kg(C).hm-2。长期均衡施用氮、磷、钾化肥或氮、磷、钾化肥配施有机肥后,小麦、玉米和大豆农田生态系统的固碳量和土壤CO2排放总量均明显增加,并在氮、磷、钾配施有机肥处理下达到最高。不同的施肥管理措施将改变土壤-植物系统作为大气CO2"汇"的程度,总体表现为化肥均衡施用下NEP值较高,而化肥与有机肥配施下农田生态系统的NEP值较低。  相似文献   

节水条件下盐碱农田施用有机肥的固碳及其生态系统服务价值提升效应          下载免费PDF全文

胡敏  李越  吕轲彦  陈志君  熊云武  黄冠华 《农业工程学报》2023,39(18):92-101

针对中国黄河中上游河套灌区不合理灌溉和施肥造成的盐碱农田碳排放加剧和生态系统服务功能退化等问题，该研究以向日葵盐碱农田为研究对象，开展连续2 a的田间试验，探讨滴灌条件下有机肥施用对盐碱农田生态系统净碳收支和生态系统服务功能价值的影响。试验设置滴灌灌水下限及施肥模式2个因素。灌水下限设置2个水平（W1：土壤基质势阈值为−20 kPa，W2：土壤基质势阈值为−30 kPa），每个灌水下限下设置3种施肥模式（CK：纯施化肥，LBF：褐煤碳基有机肥4.5 t/hm²，SMF：羊粪堆肥5 t/hm²），采用完全随机区组设计。另设畦灌施加化肥处理作为对照（MCK）。对不同处理的生态系统净碳收支及其组成要素以及3种生态系统服务价值（农产品供给功能价值、积累有机质功能价值和气体调节价值）进行了对比分析。结果表明：相同施肥条件下，滴灌处理的土壤有机质含量、作物净初级生产力、籽粒碳输出和土壤碳排放高于畦灌处理，且这些指标的值均随土壤基质势升高而增加。相同灌溉条件下，施加有机肥处理可以显著提高土壤有机质含量、净初级生产力和籽粒碳输出并降低土壤碳排放。其中，滴灌灌水下限−20 kPa与褐煤碳基有机肥用量4.5 t/hm²（W1LBF）相结合的处理有效促进了作物生长，并获得了最高的净初级生产力以及较低的土壤碳排放量，最终获得了最高的生态系统碳汇能力。此外，净初级生产力、土壤有机质和土壤碳排放等指标的变化影响了生态系统服价值。与MCK处理相比，W1LBF处理能够显著提升农产品供给功能价值、积累有机质功能价值和气体调节价值，增幅分别为8004.20、923.9和2094.70元/hm²。综上所述，该研究发现在河套灌区向日葵盐碱农田中，采用滴灌−20 kPa灌水下限结合4.5 t/hm²褐煤碳基有机肥可以增加作物初级净生产力、提高盐碱农田系统的碳汇能力和生态系统服务功能价值。该研究可为干旱半干旱地区盐碱向日葵农田固碳减排和生态系统可持续发展提供科学依据。  相似文献   

草地和农田生态系统中黑土活性有机碳的特征   总被引：2，自引：0，他引：2  

梁尧  韩晓增  王凤菊  王凤仙 《土壤通报》2011,(4):864-871

为阐明植被覆盖与施肥管理综合作用下黑土活性有机碳的数量特征,探讨合理调控农田土壤质量的施肥模式。本试验以中国科学院海伦农业生态实验站长期定位试验为平台,对比和研究了草地与农田生态系统中不同施肥处理下土壤总有机碳、颗粒有机碳、微生物生物量碳、冷水提取有机碳以及热水提取有机碳数量上的差异及相互关系。结果表明:经过25年的自然恢复,草地生态系统中土壤有机碳及各活性有机碳的数量显著高于农田生态系统中的无肥处理(P<0.05)。农田生态系统中,化肥处理对农田土壤有机碳和活性有机碳的提高作用并不明显;经过长期化肥+有机肥处理后,农田土壤总有机碳与各活性组分的数量较无肥和化肥处理显著提高(P<0.05),除微生物生物量碳外,总有机碳与其他活性有机碳组分的数量均达到草地植被下的碳水平,土壤总有机碳及冷水和热水提取有机碳的含量与草地生态系统的差异不显著,颗粒有机碳含量比草地生态系统坛加43.7%。相关性分析表明,土壤有机碳总量、微生物生物量碳、冷水提取有机碳以及热水提取有机碳两两之间的相关性均达到显著或极显著水平。长期化肥与有机肥配施是提高黑土有机碳及其活性有机碳数量的有效措施。  相似文献   

吉林省长时间序列陆地生态系统NPP时空变化特征   总被引：1，自引：0，他引：1  

严俊霞  黄浩  高彦华  王甜甜  张莹 《水土保持学报》2021,35(5):172-180

植被净初级生产力(NPP)是陆地生态系统碳循环过程中的重要组成部分,也是评价碳源/汇的重要环节。基于2001—2019年MODIS地表反射率数据(MOD09A1)、气温和日照时间资料,利用光能利用率模型估算了吉林省陆地生态系统NPP,采用趋势分析、空间变异性分析等方法,分析了吉林省陆地生态系统NPP的时空变化特征及其与气候因子的相关性。结果表明:(1)2001—2019年,吉林省植被NPP年均值与总量均成波动上升趋势,辖区内植被NPP总量表现为森林农田草地。(2)2001—2019年NPP分布表现出明显的空间差异性,大部分区域NPP呈现增加趋势,总体变异性稳定,但西北部区域NPP空间变异程度较大,与该地区施行退耕还林和治理草地退化、沙化、盐碱化有一定关联,植被恢复明显。(3)吉林省植被NPP与年均气温、年降水量的相关性存在一定的地域差异性,研究区大部分区域与气温呈正相关关系,小部分区域与降水量呈现出正相关。  相似文献   

伊犁河谷农田生态系统生产力水平对碳源汇的影响   总被引：1，自引：0，他引：1  

郝维维  苏丽丽  徐文修  王娜  赵国军  李亚杰 《水土保持通报》2016,36(5):288-293

[目的]分析伊犁河谷农田生态系统碳源汇的变化趋势及农田生态系统碳源汇的影响因素,为农业产业结构调整和农业生产固碳减排提供科学依据。[方法]以2004—2013年伊犁河谷农作物产量、播种面积、农业投入等相关统计数据为依据,采用碳转化系数的方法对伊犁河谷农田生态系统主要碳源汇进行测算。[结果](1)近10a来,伊犁河谷农田生态系统碳吸收总量由2004年的2.32×106 t升到2013年的4.48×106 t,平均增长率为7.57%,单位播种面积碳吸收量也由2004年的7.54t/hm2上升到2013年9.27t/hm2,提高了0.23倍。碳吸收量与水稻、小麦、玉米、蔬菜总产量呈极显著相关与胡麻总产量呈显著负相关。(2)碳排放总量由2004年的2.24×105 t增加到2013年的4.02×105t,10a间增加了0.80倍。对农田生态系统碳排放总量贡献最大的因素为柴油和化肥投入。(3)近10a间,净碳吸收总量由2004年的2.10×106 t增至2013年的4.07×106 t,单位播种面积净碳吸收量由2004年的6.81t/hm2上升至2013年的8.44t/hm2,年均增速2.41%。[结论]在伊犁河谷农业生产的高投入、高产出的模式下,其农田生态系统表现为碳汇系统。  相似文献   

土地利用/覆被变化对鄂尔多斯市草地生态系统净初级生产力的影响   总被引：1，自引：1，他引：0  

黄露  周伟  李浩然  周富春  杨晗 《水土保持通报》2018,38(4):46-52,59

[目的]探究土地利用/覆被变化对鄂尔多斯市草地生态系统净初级生产力(NPP)的影响,为该区退牧还草措施的高效实施和草地资源的合理管理提供理论依据。[方法]基于多源遥感影像数据、多期土地利用/覆被数据和气象数据等,运用光能利用率模型(CASA),模拟鄂尔多斯市草地生态系统净初级生产力(NPP),并进行分析和探讨。[结果](1)鄂尔多斯地区草地NPP总量在2001年(5 700.16Tg)到2015年(7 634.61Tg)间增加了1 934.46Tg;空间分布上存在明显的地域差异性。(2)该市2001—2015年耕地面积持续减少;15a间,林地面积增加了4 593km~2;草地净减少量为786.38km~2,其中草地与未利用地之间的相互转化最大,有大量耕地、林地转变为草地,面积达到376.5km~2。(3)该市2001—2015年草地类型未发生变化地区NPP增长量为1 999.42Tg;草地转为其他土地类型共引起草地NPP减少量为303.98Tg,其中转为耕地、林地和未利用地导致其NPP减少量分别为35.08,69.81和118.28Tg;其他土地类型转化为草地导致NPP的总增加量达128.96Tg,其中由耕地、林地、水域、未利用地转化带来的草地NPP增量分别为36.30,31.39,17.58,151.38Tg。[结论]土地利用/覆被对草地NPP影响较大,耕地和林地向草地的转化、未利用地的重新利用使得草地碳汇总量增加。草地向未利用地、水域、城乡工矿居民用地的转化使得草地生态系统碳汇能力减弱。  相似文献   

长期施肥下红壤旱地土壤CO2排放及碳平衡特征   总被引：2，自引：0，他引：2  

黄晶  李冬初  刘淑军  刘宏斌  王伯仁 《植物营养与肥料学报》2012,18(3):602-610

在国家肥力网红壤旱地长期定位试验地上,采用静态箱/气相色谱法测定土壤CO2排放速率,同时利用根去除法区分根系对土壤呼吸的贡献,通过计算净生态系统生产力（NEP）,判断长期不同施肥下红壤旱地农田碳汇强度。结果表明,小麦、玉米生长季各处理的土壤和土体呼吸速率随着作物生长、温度升高均呈现明显的季节变化规律;玉米生长季土壤和土体累积呼吸量大于小麦生长季,小麦、玉米生长季均以NPKM处理土壤和土体呼吸累积呼吸量最大,且显著高于其它处理（P0.05）,NP和NPK处理次之,CK和NK处理最小（P0.05）;小麦、玉米生长季各处理根际呼吸占土壤呼吸的比例分别为7.6 %～17.4 %、4.7%～16.6 %,均以NPKM处理根际呼吸贡献率最大;小麦季NPKM处理、玉米季CK和NPKM处理的NEP值为负,是大气CO2的汇,且NPKM处理的净初级生产力与土壤呼吸的比值（NPP/Rs）最大,其它处理NEP值均为正,是大气CO2的源。有机无机肥配施（NPKM）相比其它处理具有较强的碳汇功能,是红壤旱地比较合理的施肥措施。  相似文献   

基于ZGS和TW模型的长江流域植被NPP时空演变特征   总被引：1，自引：1，他引：0  

徐勇  周清华  窦世卿  郭振东  吴杰峰  郑志威 《水土保持通报》2022,42(1):225-232

[目的]研究长江流域陆地植被生态系统初级净生产力(NPP)的时空演变特征,为政府部门建立和调整生态功能恢复项目提供参考。[方法]以长江流域为研究区,基于2000—2019年的降水和气温数据,采用周广胜—张新时模型(ZGS)和Thornthwaite Memorial (TM)模型估算NPP,并进一步利用皮尔逊相关分析、一元线性回归分析、Mann-Kendall显著性检验等,对比分析长江流域陆地植被生态系统NPP时空演变特征。[结果](1)基于上述两个模型模拟得到的长江流域NPP时空演变趋势基本一致,相关系数R为0.982,呈现显著正相关关系;(2)2000—2019年长江流域陆地植被生态系统实际NPP与潜在NPP均呈上升趋势,上升速率分别为6.85,2.74 g/(m~2·a)。(3)长江流域实际NPP和潜在NPP在空间上呈东南高西北低的分布格局,低值区域主要分布在草地生态系统;高值区域大部分分布在森林生态系统和农田生态系统。(4)2000—2019年长江流域实际NPP与潜在NPP呈上升趋势的面积分别占研究区总面积的80.65%和84.81%,主要分布在云南、青海、西藏、四川北部及浙江...  相似文献   

土地利用变化与长期施肥对黑土有机碳密度的影响   总被引：4，自引：2，他引：4  

尤孟阳  李海波  韩晓增 《水土保持学报》2010,24(2)

土壤管理方式影响土壤碳库储量,进而影响土壤的源汇功能。该研究通过测定草地(GL)、裸地(BL)、农田无肥(NF)、化肥(NP)和化肥配施有机肥(NPM)处理的有机碳含量和土壤容重,估算了不同土地利用和施肥管理方式下的土壤有机碳密度的变化及农田的固碳潜力。结果表明,土壤有机碳含量表层最高而且变化较大,向下逐渐降低且变化较小。对于不同植被覆盖的3个处理,草地0-20cm土层土壤有机碳含量比裸地和无肥分别高出20.6%和16.4%。对于不同施肥管理方式,化肥有机肥配施土壤有机碳含量比无肥和化肥分别高出25.4%和15.5%,所有处理有机碳含量在160-200cm土层没有显著差异。0-40cm土层及0-100cm土体有机碳密度的变化趋势是NPMGLNPNFBL;40cm以下有机碳储量无规律性变化,表现出较大的变异性,这可能与土壤本身的空间异质性有关。草地100cm土体有机碳储量比裸地和无肥分别增加6.8%和5.7%,裸地和无肥无显著差异;化肥加有机肥100cm土体有机碳储量比化肥和无肥分别增加10.4%和5.9%。经估算,松嫩平原黑土区0-100cm土体有机碳库储量约为1.35Pg,农田有机培肥后碳库储量可达到0.96Pg,其固碳潜力约为0.05Pg。0-100cm土体有机碳密度与0-20cm土层有机碳含量及有机碳密度呈极显著正相关(r=0.99;r=0.97,P0.01),表明土壤表层有机碳含量及密度对0-100cm土壤有机碳库具有决定作用。  相似文献   

Carbon and nitrogen contents and greenhouse gas fluxes of the Eurasian steppe soils with different land-use histories located in the Arkaim museum reserve of South Ural,Russia     

Hirohiko Nagano  Soh Sugihara  Miwa Matsushima  Susumu Okitsu  Valentina E. Prikhodko  Elena Manakhova 《Soil Science and Plant Nutrition》2013,59(2):238-244

The effects of different land-use histories on contents of soil carbon (C) and nitrogen (N) and fluxes of greenhouse gases [carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O)] measured using the closed chamber method were investigated in the Arkaim museum reserve located in the South Ural of Russia. A natural forest site (NF) and two grassland sites that had different land-use histories (CL: cropland until 1991; PST: pasture until 1991; both sites have been fallow for 18 years) were selected for soil sampling and gas flux measurements. The vegetation in NF was mainly Betula pendula Roth. with steppe cherry and grassy cover. Perennial grasses (Stipa spp., Festuca spp. and others) have been planted in CL and PST since 1991 to establish reserve mode, and the projective cover of these plants were?>?90% in both sites in 2009. Soil samples were taken from the A horizon in the three sites, and additionally samples of the O horizon were taken from NF. The contents of soil C and N [total C, total N, soluble organic C, soluble N and microbial biomass C (MBC)] in the O horizon of NF were the largest among all investigated soils (p?p?2 fluxes (i.e., CO₂ efflux) in all three investigated sites were observed. The CO₂ efflux in NF was significantly larger than in CL and PST (129, 30 and 25?mg C m^?2 hour^?1, respectively, p?2 efflux between CL and PST. There were no significant differences in the fluxes of CH₄ and N₂O among NF, CL and PST (p?>?0.05). Our current research indicated that, in soils of the Eurasian steppe zone of Russia, total C, total N and MBC were affected not only by current land-use (i.e., fallow grassland vs. natural forest) but also by past (until 18 years ago) land-use.  相似文献   

不同管理措施对滨海盐渍农田土壤CO₂排放及碳平衡的影响   总被引：1，自引：0，他引：1  

米迎宾  杨劲松  姚荣江  余世鹏 《土壤》2016,48(3):546-552

为探讨不同管理措施对滨海盐渍农田碳平衡的影响,本文通过玉米–小麦轮作试验,研究农田土壤的CO_2释放规律,及其农田碳收支状况。试验设计6个处理:1常规对照(CK);2有机肥常量(OF);3氮肥增施(NF);4秸秆还田(S);5有机肥加秸秆(OF+S);6免耕(NT)。研究表明,秸秆还田和有机肥的施用增加了土壤呼吸的强度,而免耕处理的CO_2平均释放量最低,不同处理下土壤呼吸总体表现为OF+SSOMNFCKNT。各处理土壤有机碳含量随着作物的收获逐渐升高,其中OF与NT增加最多,而增施氮肥处理并没有显著提高土壤的有机碳水平。各处理间的有机碳含量没有显著性差异。在两季作物种植结束后,各处理的碳输入均高于碳输出,均为碳净输入,表现出较强的碳汇特征。秸秆还田和单施有机肥的碳净输入均显著高于对照,可有效减缓因农田土壤CO_2排放而造成的全球气候变化问题。  相似文献   

不同培肥模式下闽东茶园水土及其氮磷流失特征     

王利民  林新坚  黄东风  李卫华  范平 《水土保持通报》2015,35(4):69-72,78

[目的]研究不同培肥模式对闽东茶园水土及其氮磷流失的影响,为该区茶园水土流失评价及防控提供科学依据。[方法]通过径流小区试验,设置6个处理:全量化肥(NPK),半量化肥+半量有机肥(1/2NPKOM),全量有机肥(OM),全量化肥+豆科绿肥(NPKL),半量化肥+半量有机肥+豆科绿肥(1/2NPKOM+L)和不施肥(CK)。[结果]不同培肥处理下径流流失量的大小顺序为:OM1/2NPKOMCKNPKL1/2NPKOM+LNPK,泥沙流失量表现为:OM1/2NPKOMNPKLCKNPK1/2NPKOM+L;OM处理中径流携带的全氮、可溶性氮、硝态氮、铵态氮、全磷、可溶性磷等氮磷组分的流失量均较高,而1/2NPKOM+L中这些氮磷组分流失量则相对较低,且泥沙结合态的全氮、全磷流失量在各处理中也有类似的变化规律。[结论]1/2NPKOM+L处理在减控茶园水土及其氮磷流失方面具有良好的保土保肥效果。  相似文献   

Carbon Dioxide Emission from Black Soil as Influenced by Land‐Use Change and Long‐Term Fertilization     

《Communications in Soil Science and Plant Analysis》2012,43(7-8):1350-1368

Land‐use change and soil management play a vital role in influencing losses of soil carbon (C) by respiration. The aim of this experiment was to examine the impact of natural vegetation restoration and long‐term fertilization on the seasonal pattern of soil respiration and cumulative carbon dioxide (CO₂) emission from a black soil of northeast China. Soil respiration rate fluctuated greatly during the growing season in grassland (GL), ranging from 278 to 1030 mg CO₂ m^?2 h^?1 with an average of 606 mg CO₂ m^?2 h^?1. By contrast, soil CO₂ emission did not change in bareland (BL) as much as in GL. For cropland (CL), including three treatments [CK (no fertilizer application), nitrogen, phosphorus and potassium application (NPK), and NPK together with organic manure (OM)], soil CO₂ emission gradually increased with the growth of maize after seedling with an increasing order of CK < NPM < OM, reaching a maximum on 17 August and declining thereafter. A highly significant exponential correlation was observed between soil temperature and soil CO₂ emission for GL during the late growing season (from 3 August to 28 September) with Q₁₀ = 2.46, which accounted for approximately 75% of emission variability. However, no correlation was found between the two parameters for BL and CL. Seasonal CO₂ emission from rhizosphere soil changed in line with the overall soil respiration, which averaged 184, 407, and 584 mg CO₂ m^?2 h^?1, with peaks at 614, 1260, and 1770 mg CO₂ m^?2 h^?1 for CK, NPK, and OM, respectively. SOM‐derived CO₂ emission of root free‐soil, including basal soil respiration and plant residue–derived microbial decomposition, averaged 132, 132, and 136 mg CO₂ m^?2 h^?1, respectively, showing no difference for the three CL treatments. Cumulative soil CO₂ emissions decreased in the order OM > GL > NPK > CK > BL. The cumulative rhizosphere‐derived CO₂ emissions during the growing season of maize in cropland accounted for about 67, 74, and 80% of the overall CO₂ emissions for CK, NPK, and OM, respectively. Cumulative CO₂ emissions were found to significantly correlate with SOC stocks (r = 0.92, n = 5, P < 0.05) as well as with SOC concentration (r = 0.97, n = 5, P < 0.01). We concluded that natural vegetation restoration and long‐term application of organic manure substantially increased C sequestration into soil rather than C losses for the black soil. These results are of great significance to properly manage black soil as a large C pool in northeast China.  相似文献   

Evaluation of the soil carbon budget under different upland cropping systems in central Hokkaido,Japan     

《Soil Science and Plant Nutrition》2013,59(4):650-661

Abstract

To evaluate the carbon budget in soils under different cropping systems, the carbon dioxide (CO₂) flux from soils was measured in a total of 11 upland crop fields within a small watershed in central Hokkaido over the no snow cover months for 3 years. The CO₂ flux was measured using a closed chamber method at bare plots established in each field to estimate soil organic matter decomposition. Temporal variation in instantaneous soil CO₂ fluxes within the sites was mainly controlled by soil temperature and moisture. Annual mean CO₂ fluxes and cumulative CO₂ emissions had no significant relationship with soil temperature and moisture (P > 0.2). However, there was a significant quadratic relationship between annual mean CO₂ flux or cumulative CO₂ emission and soil clay plus silt content (%) (R² = 0.72～0.74, P < 0.0003). According to this relationship, the optimum condition for soil CO₂ emission is at a clay plus silt content of 63%. The cumulative CO₂ emission during the no snow cover season within each year varied from 1,159 to 7,349 kg C ha^?1 at the different sites. The amount of crop residue carbon retained in the soils following a cropping season was not enough to offset the CO₂ emission from soil organic matter decomposition at all sites. As a consequence, the calculation of the soil carbon budget (i.e. the difference between the carbon added as crop residues and compost and the carbon lost as CO₂ from organic matter decomposition) ranged from –7,349 to –785 kg C ha^?1, except for a wheat site where a positive value of 4,901 kg C ha^?1 was observed because of a large input of organic carbon with compost. The negative values of the soil carbon budget indicate that these cropping systems were net sources of atmospheric CO₂.  相似文献   

农田改为农林(草)复合系统对红壤CO₂和N₂O排放的影响   总被引：1，自引：0，他引：1  

郭忠录  郑珉娇  丁树文  李朝霞  蔡崇法 《中国生态农业学报》2012,20(9):1191-1196

以鄂南玉米地、紫穗槐/玉米地、香根草/玉米地、紫穗槐林地、香根草草地与撂荒地6种土地利用类型为研究对象,利用静态箱法,对夏玉米生长期间土壤CO2和N2O通量及影响因子进行了测定,研究我国北亚热带丘陵红壤区农田改变为林(草)地和农林(草)复合系统后土壤CO2和N2O排放特征。研究结果表明:(1)土地利用方式改变后,撂荒地土壤CO2排放量明显低于其他5种土地利用类型,但紫穗槐/玉米地、单作玉米地、香根草/玉米地、紫穗槐林地、香根草草地5种土地利用类型之间土壤CO2排放量差异不显著。(2)玉米生长期间,6种不同土地利用方式下,土壤N2O排放总量从高到低依次为紫穗槐/玉米地(508 g·hm-2·a-1)、紫穗槐林地(470 g·hm-2·a-1)、撂荒地(390 g·hm-2·a-1)、香根草/玉米地(373 g·hm-2·a-1)、香根草草地(372 g·hm-2·a-1)、单作玉米地(285 g·hm-2·a-1)。(3)土壤CO2通量与土壤有机碳、土壤微生物生物量碳和土壤含水量无显著相关关系;土壤N2O通量与土壤氮素净矿化率呈显著线性相关,但与土壤无机氮和土壤含水量无显著相关关系。农田改变为农林(草)复合系统可能潜在地增加土壤CO2和N2O排放;农田改变为林(草)地可能潜在地减少土壤CO2排放,增加土壤N2O排放。  相似文献   

Greenhouse gas flux from cropland and restored wetlands in the Prairie Pothole Region     

Robert A. Gleason  Brian A. Tangen  Ned H. Euliss Jr. 《Soil biology & biochemistry》2009,41(12):2501-3389

It has been well documented that restored wetlands in the Prairie Pothole Region of North America do store carbon. However, the net benefit of carbon sequestration in wetlands in terms of a reduction in global warming forcing has often been questioned because of potentially greater emissions of greenhouse gases (GHGs) such as nitrous oxide (N₂O) and methane (CH₄). We compared gas emissions (N₂O, CH₄, carbon dioxide [CO₂]) and soil moisture and temperature from eight cropland and eight restored grassland wetlands in the Prairie Pothole Region from May to October, 2003, to better understand the atmospheric carbon mitigation potential of restored wetlands. Results show that carbon dioxide contributed the most (90%) to net-GHG flux, followed by CH₄ (9%) and N₂O (1%). Fluxes of N₂O, CH₄, CO₂, and their combined global warming potential (CO₂ equivalents) did not significantly differ between cropland and grassland wetlands. The seasonal pattern in flux was similar in cropland and grassland wetlands with peak emissions of N₂O and CH₄ occurring when soil water-filled pore space (WFPS) was 40-60% and >60%, respectively; negative CH₄ fluxes were observed when WFPS approached 40%. Negative CH₄ fluxes from grassland wetlands occurred earlier in the season and were more pronounced than those from cropland sites because WFPS declined more rapidly in grassland wetlands; this decline was likely due to higher infiltration and evapotranspiration rates associated with grasslands. Our results suggest that restoring cropland wetlands does not result in greater emissions of N₂O and CH₄, and therefore would not offset potential soil carbon sequestration. These findings, however, are limited to a small sample of seasonal wetlands with relatively short hydroperiods. A more comprehensive assessment of the GHG mitigation potential of restored wetlands should include a diversity of wetland types and land-use practices and consider the impact of variable climatic cycles that affect wetland hydrology.  相似文献   

Impact of land-use types on soil nitrogen net mineralization in the sandstorm and water source area of Beijing,China   总被引：1，自引：0，他引：1  

Lilin Yang  Fusuo Zhang  Qiang Gao  Renzhao Mao  Xiaojing Liu 《CATENA》2010

Changes of land-use type (LUT) can affect soil nutrient pools and cycling processes that relate long-term sustainability of ecosystem, and can also affect atmospheric CO₂ concentrations and global warming through soil respiration. We conducted a comparative study to determine NH₄⁺ and NO₃⁻ concentrations in soil profiles (0–200 cm) and examined the net nitrogen (N) mineralization and net nitrification in soil surface (0–20 cm) of adjacent naturally regenerated secondary forests (NSF), man-made forests (MMF), grasslands and cropland soils from the windy arid and semi-arid Hebei plateau, the sandstorm and water source area of Beijing, China. Cropland and grassland soils showed significantly higher inorganic N concentrations than forest soils. NO₃⁻-N accounted for 50–90% of inorganic N in cropland and grassland soils, while NH₄⁺-N was the main form of inorganic N in NSF and MMF soils. Average net N-mineralization rates (mg kg⁻¹ d⁻¹) were much higher in native ecosystems (1.51 for NSF soils and 1.24 for grassland soils) than in human disturbed LUT (0.15 for cropland soils and 0.85 for MMF soils). Net ammonification was low in all the LUT while net nitrification was the major process of net N mineralization. For more insight in urea transformation, the increase in NH₄⁺ and, NO₃⁻ concentrations as well as C mineralization after urea addition was analyzed on whole soils. Urea application stimulated the net soil C mineralization and urea transformation pattern was consistent with net soil N mineralization, except that the rate was slightly slower. Land-use conversion from NSF to MMF, or from grassland to cropland decreased soil net N mineralization, but increased net nitrification after 40 years or 70 years, respectively. The observed higher rates of net nitrification suggested that land-use conversions in the Hebei plateau might lead to N losses in the form of nitrate.  相似文献   

长期施肥对浙江稻田土壤团聚体及其有机碳分布的影响   总被引：20，自引：0，他引：20  

毛霞丽  陆扣萍  何丽芝  宋照亮  徐祖祥  杨文叶  徐进  王海龙 《土壤学报》2015,52(4):828-838

以浙江省稻田长期定位试验站为依托,研究长期不同施肥措施对土壤团聚体及其有机碳分布的影响。研究结果表明,与不施肥对照(CK)相比,栏肥与化肥配施(NPKOM)、单施栏肥(OM)、秸秆与化肥配施(NPKRS)和单施秸秆(RS)处理均显著提高了2 mm和2~0.25 mm水稳定性大团聚体的含量和团聚体平均重量直径(p0.05),强化了团聚体对土壤有机碳的物理保护作用。此外,长期有机无机配施(NPKOM和NPKRS)处理显著提高了各个粒级团聚体中有机碳含量,并且显著增加水稳定性大团聚体有机碳的贡献率,而长期单施化肥和单施秸秆处理并未有效增加土壤总有机碳含量。不同施肥处理下,2~0.25 mm粒级团聚体有机碳占土壤总有机碳的34.2%~48.6%,是土壤有机碳的主要载体。利用傅立叶变换红外光谱(FT-IR)技术对2~0.25 mm和0.053 mm团聚体进行结构表征,发现长期单施有机肥或者有机无机配施下芳香族C较CK提高29.9%~45.2%,较NPK处理提高22.3%~36.6%,提高了土壤有机碳的芳构化。在有机碳积累方面,施用有机肥,尤其是栏肥与化肥配施,同时强化了团聚体对有机碳的物理保护以及促进了化学抗性有机碳组分的积累,是加强稻田土壤有机碳库积累的合理施肥模式。  相似文献