共查询到20条相似文献,搜索用时 15 毫秒
1.
工业革命以来,大气CO2浓度持续上升,升高的CO2浓度会改变植物光合产物积累、土壤碳库的碳输入和碳输出过程,进而通过影响有机碳组成和周转特征来调控土壤碳库动态变化。土壤碳库是陆地生态系统碳库的重要组成部分,其碳储量的微小变化都会对大气CO2浓度和气候变化产生巨大影响。但目前关于CO2浓度升高对土壤碳库动态和稳定性的影响还不清楚,很大程度上限制了预测陆地生态系统碳循环对气候变化的反馈。系统综述国内外大气CO2浓度升高对植被生产力、植被碳输入和土壤碳库影响的研究进展,旨在揭示土壤碳库物理、化学组成以及周转特征对CO2浓度升高的响应过程和机理,探讨CO2升高情境下土壤微生物特征对土壤碳库稳定性的影响和驱动机制,为深入理解全球变化下的土壤碳循环特征提供理论支撑。 相似文献
2.
城市小型景观水体CO2与CH4排放特征及影响因素 总被引:1,自引:0,他引:1
淡水生态系统被认为是大气温室气体排放的重要来源,尤其在人类活动影响下,其排放强度可能进一步增强。城市小型景观水体是城市生态系统的重要组成,具有面积小、数量大以及人类干扰强的特征,其温室气体排放特征及影响因素尚不清楚。选择重庆市大学城8个景观水体和周边2个自然水体为对象,于2019年1、4、7、10月,利用漂浮箱和顶空法分析了水体CO2与CH4的溶存浓度及排放通量,旨在揭示城市小型景观水体CO2与CH4排放强度、时空变异特征以及影响因素。结果表明,10个小型水体CO2、CH4的溶存浓度范围分别为10.75-116.25 μmol/L和0.09-3.61 μmol/L(均值分别为(47.6±29.3)μmol/L、(1.13±0.56)μmol/L),均为过饱和状态;漂浮箱法实测的8个景观水体CO2和CH4排放通量均值分别为(72.7±65.9)mmol m-2 d-1和(2.31±3.48)mmol m-2 d-1(顶空法估算值为(69.7±82.0)mmol m-2 d-1和(3.69±2.92)mmol m-2 d-1),是2个自然水体的3.5-6.1和2.0-4.5倍,呈较强的CO2、CH4排放源;居民区景观水体CO2和CH4排放略高于校园区,均显著高于对照的自然水体;CO2排放夏季最高,秋季次之,冬、春季最低,CH4呈夏季>秋季≈春季>冬季的季节模式,温度和水体初级生产共同影响CO2和CH4排放的季节模式;水生植物分布对景观水体CO2、CH4排放有显著影响,有植物分布的水域比无植物水域平均高1.97和2.94倍;漂浮箱法和顶空法测得气体通量线性关系较好,但顶空法测得CO2通量在春季明显偏低,而CH4则普遍偏高。相关分析表明,景观水体碳、氮浓度、pH值以及DO等对CO2排放具有较好的指示性,CH4排放通量主要与水体中碳、磷浓度有关。城市小型景观水体CO2、CH4排放通量远高于大部分已有自然水体的研究结果,呈一种较强的大气温室气体排放源,在区域淡水系统温室气体排放清单中具有重要贡献,未来研究中应给以更多关注。 相似文献
3.
春玉米-晚稻与早稻-晚稻种植模式碳足迹比较 总被引:2,自引:0,他引:2
量化作物生产的碳足迹有助于为农业生态系统温室气体减排提供理论依据。利用生命周期法研究了我国南方地区稻田春玉米-晚稻水旱轮作种植模式和早稻-晚稻连作种植模式下粮食生产的碳足迹,并定量分析粮食生产过程中各种碳排放源的相对贡献。结果表明,与早稻-晚稻的连作模式相比,春玉米-晚稻轮作模式的单位面积碳排放降低了6724 kg CO2-eq/hm2,单位产量的碳足迹降低了0.56 kg CO2-eq/kg。春玉米比早稻少排放6228 kg CO2-eq/hm2;与早稻-晚稻模式中晚稻碳排放相比,春玉米-晚稻轮作模式晚稻碳排放降低了497 kg CO2-eq/hm2。早稻-晚稻种植模式的碳足迹主要来源于甲烷(CH4),其碳排放为9776 kg CO2-eq/hm2(54.8%),氮肥生产和施用的碳排放为2871 kg CO2-eq/hm2(16.1%),灌溉电力消耗的碳排放2849 kg CO2-eq/hm2(16.0%)。春玉米-晚稻轮作模式的碳足迹主要来源于CH4的碳排放4442 kg CO2-eq/hm2(39.9%),氮肥生产和施用的碳排放2871 kg CO2-eq/hm2(25.8%),灌溉电力消耗的碳排放1508 kg CO2-eq/hm2(13.6%)。该模式中晚稻的碳足迹组成情况与春玉米-晚稻模式的碳足迹相似。但是,对于春玉米而言,其碳足迹主要来源氮肥生产和施用的碳排放1436 CO2-eq/hm2(50.1%),氧化亚氮(N2O)的碳排放为579 kg CO2-eq/hm2(20.2%),CH4的碳排放为378 CO2-eq/hm2(13.2%)。同时,相比于早稻-晚稻中晚稻的产量(6333 kg/hm2),春玉米-晚稻轮作模式下的晚稻产量(7270 kg/hm2)提高了14.8%。因此,引入春玉米-晚稻轮作模式有利于提升稻田生产力,降低稻田连作系统碳排放和碳足迹。 相似文献
4.
不同恢复方式下大兴安岭重度火烧迹地林地土壤温室气体通量 总被引:3,自引:3,他引:0
为研究大兴安岭重度火烧迹地在不同恢复方式下林地土壤CO2、CH4和N2O排放特征及其影响因素,采用静态箱/气相色谱法,在2017年生长季(6月-9月)对3种恢复方式(人工更新、天然更新和人工促进天然更新)林地土壤温室气体CO2、CH4、N2O通量进行了原位观测。研究结果表明:(1)3种恢复方式林地土壤在生长季均为大气CO2、N2O的源,CH4的汇;生长季林地土壤CO2排放通量大小关系为人工促进天然更新((634.40±246.52)mg m-2 h-1) > 人工更新((603.63±213.22)mg m-2 h-1) > 天然更新((575.81±244.12)mg m-2 h-1),3种恢复方式间无显著差异;人工更新林地土壤CH4吸收通量显著高于人工促进天然更新;天然更新林地土壤N2O排放通量显著高于其他两种恢复方式。(2)土壤温度是影响3种恢复方式林地土壤温室气体通量的关键因素;土壤水分仅对人工更新林地土壤N2O通量有极显著影响(P < 0.01);3种恢复方式林地土壤CO2通量与大气湿度具有极显著的响应(P < 0.01);土壤pH仅与天然更新林地土壤CO2通量显著相关(P < 0.05);土壤全氮含量仅与人工促进天然更新林地土壤CH4通量显著相关(P < 0.05)。(3)基于100年尺度,由3种温室气体计算全球增温潜势得出,人工促进天然更新(1.83×104 kg CO2/hm2) > 人工更新(1.74×104 kg CO2/hm2) > 天然更新(1.67×104 kg CO2/hm2)。(4)阿木尔地区林地土壤年生长季CO2和N2O排放量为8.85×106 t和1.88×102 t,CH4吸收量为1.05×103 t。 相似文献
5.
Combined effects of atmospheric CO<Subscript>2</Subscript> and N availability on the belowground carbon and nitrogen dynamics of aspen mesocosms 总被引:1,自引:0,他引:1
It is uncertain whether elevated atmospheric CO2 will increase C storage in terrestrial ecosystems without concomitant increases in plant access to N. Elevated CO2 may alter microbial activities that regulate soil N availability by changing the amount or composition of organic substrates
produced by roots. Our objective was to determine the potential for elevated CO2 to change N availability in an experimental plant-soil system by affecting the acquisition of root-derived C by soil microbes.
We grew Populus tremuloides (trembling aspen) cuttings for 2 years under two levels of atmospheric CO2 (36.7 and 71.5 Pa) and at two levels of soil N (210 and 970 μg N g–1). Ambient and twice-ambient CO2 concentrations were applied using open-top chambers, and soil N availability was manipulated by mixing soils differing in
organic N content. From June to October of the second growing season, we measured midday rates of soil respiration. In August,
we pulse-labeled plants with 14CO2 and measured soil 14CO2 respiration and the 14C contents of plants, soils, and microorganisms after a 6-day chase period. In conjunction with the August radio-labeling
and again in October, we used 15N pool dilution techniques to measure in situ rates of gross N mineralization, N immobilization by microbes, and plant N uptake.
At both levels of soil N availability, elevated CO2 significantly increased whole-plant and root biomass, and marginally increased whole-plant N capital. Significant increases
in soil respiration were closely linked to increases in root biomass under elevated CO2. CO2 enrichment had no significant effect on the allometric distribution of biomass or 14C among plant components, total 14C allocation belowground, or cumulative (6-day) 14CO2 soil respiration. Elevated CO2 significantly increased microbial 14C contents, indicating greater availability of microbial substrates derived from roots. The near doubling of microbial 14C contents at elevated CO2 was a relatively small quantitative change in the belowground C cycle of our experimental system, but represents an ecologically
significant effect on the dynamics of microbial growth. Rates of plant N uptake during both 6-day periods in August and October
were significantly greater at elevated CO2, and were closely related to fine-root biomass. Gross N mineralization was not affected by elevated CO2. Despite significantly greater rates of N immobilization under elevated CO2, standing pools of microbial N were not affected by elevated CO2, suggesting that N was cycling through microbes more rapidly. Our results contained elements of both positive and negative
feedback hypotheses, and may be most relevant to young, aggrading ecosystems, where soil resources are not yet fully exploited
by plant roots. If the turnover of microbial N increases, higher rates of N immobilization may not decrease N availability
to plants under elevated CO2.
Received: 12 February 1999 / Accepted: 2 March 2000 相似文献
6.
鸟氨酸脱羧酶活性微量测定法 总被引:1,自引:0,他引:1
本文采用一种简单,微量反应系统,根据 14C-鸟氨酸释放的 14CO2量测定鸟氨酸脱羧酶(ODC)的活性,酶反应在置于液闪计数瓶内的玻璃小管中进行,释放的 14CO2被瓶内滤纸片上的海胺吸收。实验结果表明,加酸释放 14CO2后30分钟 14CO2吸收已达最大值,且吸收量与释放量成正比,酶反应测定证明 14CO2释放速度在40分钟内保持恒定。ODC活性与酶浓度呈线性关系,此方法不仅用于ODC活性测定,而且亦可用于其他脱羧酶活性的测定。 相似文献
7.
为了更好理解若尔盖高原不同微生境下沼泽湿地生态系统CO2排放通量的变化特征,以若尔盖高原湿地自然保护区为研究对象,2013和2014年生长季期间,采用了静态箱和快速温室气体法原位观测了3种湿地5种微生境下沼泽湿地CO2排放通量时空变化规律。结果表明:长期淹水微地貌草丘区湿地(PHK)和洼地区湿地(PHW) CO2排放通量变化范围分别为38.99-1731.74 mg m-2 h-1和46.69-335.22 mg m-2 h-1,季节性淹水区微地貌草丘区湿地(SHK)和洼地区湿地(SHW) CO2排放通量变化范围分别为193.90-2575.60 mg m-2 h-1和49.93-1467.45 mg m-2 h-1,而两者过渡区的无淹水区沼泽湿地(Lawn) CO2排放通量变化范围194.20-898.75 mg m-2 h-1。相关性分析表明5种微地貌区沼泽湿地CO2排放通量季节性变化与不同深度土壤温度均存在显著正相关,与水位存在显著负相关(PHW、SHW、SHK、Lawn)或不相关(PHK),并且水位和温度(5 cm)共同解释了CO2排放通量季节性变化的87%。3种湿地5种微生境下沼泽湿地CO2排放通量存在空间变化规律,主要受水位影响,但植物也影响沼泽湿地CO2排放通量空间变化规律,并且表明沼泽湿地CO2排放通量与水位平均值存在显著负相关。 相似文献
8.
Witjaksono Bruce A. Schaffer Angel M. Colls Richard E. Litz Pamela A. Moon 《In vitro cellular & developmental biology. Plant》1999,35(3):238-244
Summary The proliferation and survival of avocado nodal cultures of juvenile origin were affected by the form and concentration of
nitrogen. Optimum growth was achieved on modified Murashige and Skoog medium containing 67% KNO3 and 33% NH4NO3 with total N of 40 mM supplemented with 100 mg l−1
myo-inositol, 1 mg l−1 thiamine HCl, 30 g l−1 sucrose, and 4.44 μM BA with a 16-h photoperiod (120–150 μmol m−2 s−1). Proliferating shoots and plantlets were photosynthetically active. Better shoot growth and accumulation of higher biomass
occurred in a CO2-enriched environment than under ambient CO2 conditions. CO2 assimilation efficiency, however, was higher under the latter conditions than in a CO2-enhanced environment, e.g., 31±7 and 17±2 μmol CO2 m−2 s−1, respectively. The net CO2 assimilation rates of in vitro grown plantlets were comparable to those of seedlings ex vitro. 相似文献
9.
谷氨酸脱羧酶放射测量法的改良及应用 总被引:2,自引:0,他引:2
用NaOH代替苯乙胺作为14CO2的吸附剂,改进谷氨酸脱羧酶(GAD)活性的放射测定方法,结果发现NaOH为吸附剂组内变异系数为9.6%, 以苯乙胺为吸附剂组内变异系数为31.9%;以NaOH为吸附剂72 h后测量其放射活性仍稳定不变,以苯乙胺为吸附剂者1 h后放射性活性即下降47%,6 h后已降低至本底水平;14CO2重吸收实验亦证明以苯乙胺为吸附剂吸附的14CO2 6 h内已有80%以上重新被NaOH吸附;以NaOH作为吸附剂测定GAD的活性,在0.39~17.8 mg脑组织样品范围内GAD量与14CO2生成量之间有线性关系.NaOH代替苯乙胺作为14CO2的吸附剂测定GAD的活性其灵敏度提高1.66倍.用此方法测定组织和细胞内GAD活性证明其具有良好的重复性和稳定性,值得推广应用. 相似文献
10.
为了解重庆市中梁山岩溶槽谷区隧道建设对土壤CO2浓度变化特征的影响,于2017年12月1日至2018年11月25日对中梁山岩溶槽谷区的隧道影响区和非隧道影响区典型的白蜡树林(FC)和于2017年3月22日-2018年1月18日对耕地(CU)、灌丛(SH)、竹林(BA)下土壤CO2浓度及其相关的环境因子进行研究,探讨了隧道影响和非隧道影响的岩溶区土壤CO2浓度变化规律及其影响因子。研究表明:隧道影响区(A区)土壤CO2浓度低于非隧道影响区(B区),A区A-CU、A-SH、A-BA和A-FC土壤CO2浓度的平均值分别为4479.26、6053.10、8152.70 mg/m3和17162.47 mg/m3,B区B-CU、B-SH、B-BA和B-FC分别为6244.67、6647.01、9422.94 mg/m3和18396.09 mg/m3。但隧道影响区和非隧道影响区的土壤CO2浓度具有相同的垂直和季节变化趋势,在垂直方向上,土壤CO2浓度随土壤深度的增加而增加,在季节变化上,雨季(夏季和秋季)土壤CO2浓度大于旱季(冬季和春季)。经相关分析发现土壤温度是影响土壤CO2浓度变化的主控因子,土壤CO2浓度随土壤温度的升高而升高,降水较多时土壤含水率过高,会抑制土壤CO2的生产,同时,土壤理化性质也对土壤CO2浓度具有一定的影响。隧道影响区土壤CO2浓度的变化受外界环境变化的影响大。 相似文献
11.
草甸草原是青藏高原的重要植被类型, 与其他植被类型相比, 其碳交换过程和驱动机理的研究仍较薄弱。利用青海湖东北岸草甸草原的涡度相关系统观测的连续数据(2010年7月1日–2011年6月30日), 分析了草甸草原CO2通量特征及其驱动因子。结果表明: 草甸草原净生态系统CO2交换量(NEE)在植物生长季的5–9月, 其日变化主要受控于光合光量子通量密度(PPFD); 而非生长季(10月21日–4月19日)和生长季初(4月下旬)、末期(10月中上旬) NEE的日变化主要受气温(Ta)的影响。CO2
日最大吸收值和释放值分别出现在7月1日(11.37 g CO2·m–2·d–1)和10月21日(4.04 g CO2·m–2·d–1)。逐日NEE主要受控于Ta, 两者关系可用指数线性(explinear)方程表示(R2 = 0.54, p < 0.01)。叶面积指数(LAI)和增强型植被指数(EVI)对逐日NEE的影响表现为渐近饱和型, LAI和Ta交互作用明显(p < 0.05), EVI的主效应强烈(p < 0.001)。生态系统的呼吸熵(Q10)为2.42, 总呼吸(Reco)约占总初级生产力(GPP)的74%。生长季适度的昼夜温差(<14.8 ℃)有利于系统的碳蓄积。研究时段该草甸草原作为碳汇从大气吸收271.31 g CO2· m–2。 相似文献
12.
五种模型分别运用于紫茉莉的光合—光响应及CO2响应曲线的拟合,研究其光合效率参数的变化,探讨紫茉莉光合—光响应及CO2响应的最适模型。结果表明:(1)紫茉莉的光合—光响应及CO2响应改进指数模型拟合R2均为0.999,拟合效果优于非直角双曲线、直角双曲线和直角双曲线修正模型。其饱和光强和最大净光合速率分别为797.299和7.879 μmolCO2·m-2·s-1,饱和CO2浓度和最大光合能力分别为1 264.447和16.783 μmol CO2·m-2·s-1,均与实测值最接近;(2)五个模型拟合和预测的均方误差(MSE)、平均绝对误差(MAE),都是改进指数模型小于其他模型。改进指数模型为紫茉莉光合—光响应及CO2响应曲线的最佳模型,实验结果可为紫茉莉的生理生态应用研究提供参考。 相似文献
13.
改进指数模型对紫茉莉光合-光响应及CO2响应适用性研究 总被引:1,自引:0,他引:1
五种模型分别运用于紫茉莉的光合—光响应及CO2响应曲线的拟合,研究其光合效率参数的变化,探讨紫茉莉光合—光响应及CO2响应的最适模型。结果表明:(1)紫茉莉的光合—光响应及CO2响应改进指数模型拟合R2均为0.999,拟合效果优于非直角双曲线、直角双曲线和直角双曲线修正模型。其饱和光强和最大净光合速率分别为797.299和7.879 μmolCO2·m-2·s-1,饱和CO2浓度和最大光合能力分别为1 264.447和16.783 μmol CO2·m-2·s-1,均与实测值最接近;(2)五个模型拟合和预测的均方误差(MSE)、平均绝对误差(MAE),都是改进指数模型小于其他模型。改进指数模型为紫茉莉光合—光响应及CO2响应曲线的最佳模型,实验结果可为紫茉莉的生理生态应用研究提供参考。 相似文献
14.
为研究枯落物输入变化对云南松(Pinus yunnanensis)林地CO2释放的影响。本研究于2018年3月至2020年2月,应用枯落物添加和去除实验(DIRT),设置对照(CK)、双倍枯落物(DL)、去除枯落物(NL)、去除有机层和A层(O/A-Less)、去除根系(NR)和无输入(NI)6个处理水平,采用Li-6400便携式光合作用测量仪及TRIME-PICO 64/32土壤温度水分测定仪对不同处理样地每月的CO2通量(Rs)、土壤温度和土壤水分(15cm)进行了测定。结果表明:(1)不同处理样地CO2通量均呈现出明显的月变化,7至8月最高,1至4月最低,平均值表现为Rs (DL)=8.10 μmol m-2 s-1 > Rs (CK)=6.27 μmol m-2 s-1 > Rs (NL)=5.44 μmol m-2 s-1 > Rs (NR)=4.46 μmol m-2 s-1 > Rs (O/A-Less)=3.86 μmol m-2 s-1 > Rs (NI)=2.94 μmol m-2 s-1。(2)与CK相比,DL样地CO2通量升高了29.12%,而去除地上枯落物和地下根系样地CO2通量显著降低,CO2通量平均变幅分别为α(NR)=-28.85%,α(NI)=-53.14%,α(O/A-Less)=-38.46%,α(NL)=-13.29%。(3)不同处理土壤水分和土壤温度均存在显著的月变化(P<0.01),NL和O/A-Less的土壤水分显著低于CK,而其余处理与CK间无显著差异(P>0.05);不同处理间土壤温度表现为NR和NI均显著高于CK,其余处理与CK间无显著差异(P>0.05)。(4)不同处理样地CO2通量与土壤温度呈显著指数相关(P<0.01),与土壤水分在NI和O/A-Less处理中无显著相关(P>0.05);与CK相比,NI、O/A-Less和NL处理的Q10增加,而NR和DL处理的Q10则降低;不同处理林地CO2通量与土壤水热因子双因素模型能更好的解释林地CO2通量的变化。本研究表明枯落物不同处理通过改变土壤碳输入和土壤环境因子从而影响生态系统碳排放,研究结果可为未来气候变化和人为干扰下云南松林的碳循环提供基础数据。 相似文献
15.
碳捕集与封存(Carbon Capture and Storage,CCS)是应对全球气候变化、实现煤炭清洁利用的有效手段之一,但是地质封存的CO2存在泄漏的风险,可能对农田生态系统产生重大威胁,影响我国粮食安全。根系生长是地上部和地下部相互作用、相互促进的统一过程,其形态特征对作物生产力有显著影响,但CCS泄漏对植物根系的影响评估尚不多见。本文以玉米为研究对象,采用盆栽底部通入CO2的方法模拟不同CO2泄漏情景,研究CK(0 g m-2 d-1)和G1000(1000 g m-2 d-1)和G2000(2000 g m-2 d-1)三种泄漏情景下CO2对玉米根系形态的影响。结果表明:CO2泄漏对玉米根系形态有明显的影响,随着泄漏量的增大总根长从40290.81 cm减少至21448.18 cm,减少46.77%,其中细根大幅减少;CO2泄漏造成玉米明显减产,最大减产率达26.64%;玉米的地上部生物量较地下部生物量对CO2泄漏更加敏感。综合来看,随着CO2泄漏量增大,对玉米根的生长、地上部生物量、地下部生物量以及产量有显著的抑制作用。作物根系形态对封存CO2泄漏的响应可为CCS泄漏监测和生态修复提供系统科学依据。 相似文献
16.
为研究不同CO2浓度升高和氮肥水平对水稻叶绿素荧光特性的影响,利用由开顶式气室(OTC)组成的CO2浓度自动调控平台开展田间试验。以粳稻9108为试验材料,CO2浓度设置CK(对照,环境大气CO2浓度)、C1(CO2浓度比CK增加160 μmol/mol)和C2(CO2浓度比CK增加200 μmol/mol)3个水平;氮肥设置低氮(N1:10 g/m2)、中氮(N2:20 g/m2)和高氮(N3:30 g/m2)3个水平。结果表明,在低氮条件下,与CK相比,C1处理使拔节期的Fo上升4.8%(P=0.031);C2处理使拔节期的Fo上升6.3%(P=0.015),Fv/Fm下降4.8%(P=0.003),使孕穗期的Fo上升12.7%(P=0.039),Fv/Fo下降18.2%(P=0.039)。在高氮条件下,与CK相比,C2处理使灌浆期的Fm、Fv和Fv/Fm分别下降3.6%(P=0.039)、4.9%(P=0.013)和1.3%(P=0.039)。在中氮条件下,与CK相比,C1和C2处理的影响不明显。在整个生育期内,CO2浓度升高与施氮处理交互作用对水稻叶绿素荧光特性的影响未到达显著水平。研究表明,大气CO2浓度升高使水稻叶片光系统Ⅱ受损,抑制其电子传递能力、电子受体QA氧化还原情况、最大光化学效率和潜在活性,通过适量施氮可以有效地缓解其负面效应。 相似文献
17.
河口感潮沼泽是全球重要的蓝碳生态系统,具有很强的固碳能力。碳收支研究是量化生态系统碳源/汇过程及固碳规模的基础。本研究运用透明箱和不同遮光率布遮盖+红外气体分析仪/气相色谱相结合的方法,模拟不同光照条件,测定闽江河口鳝鱼滩半咸水芦苇沼泽和短叶茳芏沼泽的瞬时净生态系统二氧化碳(CO2)交换量(net ecosystem exchange,NEE)、生态系统呼吸(ecosystem respiration,ER)以及甲烷(CH4)排放通量,并通过对总光合吸收量(gross ecosystem exchange,GEE)与光合有效辐射的拟合以及ER与气温的拟合,外推2个沼泽生态系统CO2气体在月、年尺度上的NEE和ER,评估其年固碳量。2个沼泽生态系统的NEE和ER均具有明显的季节变化,春夏秋季为大气中CO2的汇,而冬季则转化为大气中CO2的源,芦苇沼泽年尺度固碳能力显著高于短叶茳芏沼泽。芦苇沼泽与短叶茳芏沼泽CH4排放通量差异不显著。综合考虑CH4排放,闽江河口鳝鱼滩半咸水芦苇沼泽、短叶茳芏沼泽生态系统年固碳量分别为(5371.52±336.97) g CO2-eq/m2和(2730.32±503.67) g CO2-eq/m2。研究表明:闽江河口半咸水沼泽湿地在年尺度上是一个较强的碳汇,在缓解全球变暖方面发挥着重要的角色。 相似文献
18.
Effects of elevated atmospheric CO2 on soil enzyme activities at different nitrogen application treatments
下载免费PDF全文
![点击此处可从《农业工程》网站下载免费的PDF全文](/ch/ext_images/free.gif)
It has been predicted that elevated atmospheric CO2 will increase enzyme activity as a result of CO2-induced carbon entering the soil. The objective of this study was to investigate the effects of elevated atmospheric CO2 on soil enzyme activities under a rice/wheat rotation. This experiment was conducted in Wuxi, Jiangsu, China as part of the China FACE (Free Air Carbon Dioxide Enrichment) Project. Two atmospheric CO2 concentrations (580±60) and (380±40) μmol·mol-1) and three N application treatments (low-150, normal-250 and high-350 kg N·hm-2) were included. Soil samples (0-10 cm) were collected for analysis of β-glucosidase, invertase, urease, acid phosphates and β-glucosaminidase activities. The results revealed that with elevated atmospheric CO2 β-glucosidase activity significantly decreased (P < 0.05) at low N application rates; had no significant effect with a normal N application rate; and significantly increased (P < 0.05) with a high N application rate. For urease activity, at low and normal N application rates (but not high N application rate), elevated atmospheric CO2 significantly increased (P < 0.05) it. With acid phosphatase elevated atmospheric CO2 only had significant higher effects (P < 0.05) at high N application rates. Under different CO2 concentration, effects of N fertilization are also different. Soil β-glucosidase activity at ambient CO2 concentration decreased with N fertilization, while it increased at elevated CO2 concentration. In addition, invertase and acid phosphatase activities at elevated CO2 concentration, significantly increased (P < 0.05) with N treatments, but there was no effect with the ambient CO2 concentration. For urease activity, at ambient CO2 concentration, N fertilization increased it significantly (P < 0.05), whereas at elevated CO2 concentration it was not significant. Additionally, with β-glucosaminidase activity, there were no significant effects from N application. In general, then, elevated atmospheric CO2 increased soil enzyme activity, which may be attributed to the following two factors: (1) elevated atmospheric CO2 led to more plant biomass in the soil, which in turn stimulated soil microbial biomass and activity; and (2) elevated atmospheric CO2 increased plant photosynthesis, thereby increasing plant-derived soil enzymes. 相似文献
19.
Xuexia Yuan Xiangui Lin Haiyan Chu Rui Yin Huayong Zhang Junli Hu Jianguo Zhu 《生态学报》2006,26(1):48-53
It has been predicted that elevated atmospheric CO2 will increase enzyme activity as a result of CO2-induced carbon entering the soil. The objective of this study was to investigate the effects of elevated atmospheric CO2 on soil enzyme activities under a rice/wheat rotation. This experiment was conducted in Wuxi, Jiangsu, China as part of the China FACE (Free Air Carbon Dioxide Enrichment) Project. Two atmospheric CO2 concentrations (580±60) and (380±40) μmol·mol-1) and three N application treatments (low-150, normal-250 and high-350 kg N·hm-2) were included. Soil samples (0-10 cm) were collected for analysis of β-glucosidase, invertase, urease, acid phosphates and β-glucosaminidase activities. The results revealed that with elevated atmospheric CO2 β-glucosidase activity significantly decreased (P < 0.05) at low N application rates; had no significant effect with a normal N application rate; and significantly increased (P < 0.05) with a high N application rate. For urease activity, at low and normal N application rates (but not high N application rate), elevated atmospheric CO2 significantly increased (P < 0.05) it. With acid phosphatase elevated atmospheric CO2 only had significant higher effects (P < 0.05) at high N application rates. Under different CO2 concentration, effects of N fertilization are also different. Soil β-glucosidase activity at ambient CO2 concentration decreased with N fertilization, while it increased at elevated CO2 concentration. In addition, invertase and acid phosphatase activities at elevated CO2 concentration, significantly increased (P < 0.05) with N treatments, but there was no effect with the ambient CO2 concentration. For urease activity, at ambient CO2 concentration, N fertilization increased it significantly (P < 0.05), whereas at elevated CO2 concentration it was not significant. Additionally, with β-glucosaminidase activity, there were no significant effects from N application. In general, then, elevated atmospheric CO2 increased soil enzyme activity, which may be attributed to the following two factors: (1) elevated atmospheric CO2 led to more plant biomass in the soil, which in turn stimulated soil microbial biomass and activity; and (2) elevated atmospheric CO2 increased plant photosynthesis, thereby increasing plant-derived soil enzymes. 相似文献
20.
杉木人工林不同深度土壤CO2通量 总被引:3,自引:0,他引:3
土壤CO2通量具有明显的时间和空间变异性。土壤温度和含水量是影响土壤CO2通量的重要因素,同时,不同深度的土壤CO2通量对温度和含水量变化的响应差异较大,因此,研究土壤CO2通量和影响因素随土壤深度的变化,对于准确评估土壤碳排放具有重要意义。选择福建三明杉木人工林(Cunninghamia lanceolata)作为研究对象,利用非散射红外CO2浓度探头和Li-8100开路式土壤碳通量系统,并使用Fick扩散法计算了0-60cm深度土壤CO2的通量,结果表明:(1)5种扩散模型计算的表层(5cm)CO2通量与Li-8100测量结果均具有显著相关性(P<0.01),Moldrup气体扩散模型计算结果较好。(2)土壤CO2浓度随深度的增加而升高,但60cm深度以下土壤CO2浓度开始降低;不同深度土壤CO2浓度的日变化均呈现单峰型;0-60cm土壤CO2通量日通量均值变化范围为0.54-2.17μmol m-2 s-1;(3)指数拟合分析显示,5、10cm和60cm深度处土壤CO2通量与温度具有显著相关性,Q10值分别为1.35、2.01和4.95。不同深度土壤含水量与CO2通量的相关性不显著。 相似文献