武振丹(1998—),女,乌兰察布市商都县人,硕士研究生,主要研究方向为草原土壤利用与保护。E-mial:
为解析贝加尔针茅草甸草原土壤有机碳组分对长期氮素添加的响应,于2010年在内蒙古呼伦贝尔市鄂温克旗贝加尔针茅草甸草原设计氮素添加试验,设置8个氮处理,为0(N0)、15(N15)、30(N30)、50(N50)、100(N100)、150(N150)、200(N200)和300(N300)kg·hm–2 ·a–1(以N计),土壤样品于2019年8月采集,进行土壤有机碳及其组分的测定,探究氮素添加10年后土壤有机碳及其组分的变化与驱动因素。结果表明:(1)与对照相比,长期氮素添加下土壤有机碳(SOC)及土壤惰性碳(RP-C)含量无显著变化,土壤活性有机碳(LP-C)的含量增加,其中活性碳组分Ⅰ(LPⅠ-C)增加了0.48%~15.59%,活性碳组分Ⅱ(LPⅡ-C)增加了1.94%~8.41%,易氧化有机碳(EOC)含量无显著变化,可溶性有机碳(DOC)与微生物生物量碳(MBC)含量显著变化,且土壤碳组分整体在N30~N100处理变化敏感;(2)分析土壤有机碳对氮素添加的敏感指数(SI)可知,MBC对长期氮素添加响应更为敏感,可作为本区域有机碳变化的指示碳组分;(3)结构方程模型(SEM)结果显示,长期氮输入条件下土壤碳组分主要受植物生物量与土壤pH的共同调控。综上所述,氮素添加提高了贝加尔针茅草甸草原土壤活性碳组分含量,且土壤有机碳及其组分的变化主要受土壤pH与植物生物量共同调控。
This study aimed to analyze the response of soil carbon composition to long-term nitrogen addition in the
A nitrogen addition experiment was designed in the meadow steppe of Ewenke Banner, Hulunbuir City, Inner Mongolia in 2010, and 8 nitrogen treatments were set as 0 (N0), 15 (N15), 30 (N30), 50 (N50), 100 (N100), 150 (N150), 200 (N200) and 300 (N300) kg·hm–2·a–1 (calculated as N). Soil samples were collected in August 2019 and soil organic carbon and its fractions were measured to investigate the changes and drivers of soil organic carbon and its fractions after 10 years of nitrogen addition.
The results showed that: (1) Compared to the control, soil organic carbon (SOC) content and soil recalcitrant carbon (RP-C) did not change significantly under long-term nitrogen addition. The content of soil labile organic carbon (LP-C) increased, among which labile carbon fraction Ⅰ (LPⅠ-C) and Ⅱ (LPⅡ-C) increased by 0.48%-15.59% and 1.94%-8.41%, respectively. Soil easily oxidized organic carbon(EOC)did not respond, whereas the contents of dissolved organic carbon (DOC) and microbial biomass carbon (MBC) changed significantly. The overall soil carbon composition was more sensitive to N addition at the level of 30, 50 and 100 kg·hm–2 ·a–1; (2) The responses of sensitivity index (SI) of soil organic carbon to nitrogen addition showed that MBC was more sensitive to long-term nitrogen addition, which could be used as an indicator suggesting the changes in organic carbon component in the region; (3) Structural equation modeling (SEM) indicated that soil carbon fractions were regulated mainly by plant biomass and soil pH under long-term nitrogen conditions.
Nitrogen addition increases soil labile carbon content in
工业革命以来,化石燃料燃烧、施肥等人类活动使得我国大气氮沉降量迅速增加[
土壤碳库作为陆地生态系统中最大的有机碳库,其微小的变化就会对自然界的物质循环与能量流动产生巨大的影响[
贝加尔针茅草原(
试验区位于内蒙古呼伦贝尔市伊敏河镇贝加尔针茅草甸草原(48°27'N~48°35'N,119°35'E~119°41'E),海拔760~770 m,地势平坦,气候类型属于大陆性温带气候,年均气温–1.6℃,年均降水量348.8 mm,年蒸发量1 478.8 mm,降水主要集中于6—9月,年均无霜期为100 d左右(
试验区气象数据
Meteorological data of the study area
试验样地于2010年6月进行围封,开展模拟氮沉降试验,采用随机区组设计,8个施氮水平,换算为纯氮量依次为0、15、30、50、100、150、200和300 kg·hm–2·a–1(不包括大气氮沉降量),分别用N0、N15、N30、N50、N100、N150、N200和N300表示,每个处理设3个重复。小区面积8 m×8 m,小区间设2 m隔离带,重复间设5 m隔离带。2010年至今,每年6月和7月中旬分两次将氮肥等量施入样地,氮肥为NH4NO3。为了尽量避免氮肥的挥发,在试验中将氮肥溶于适量水中制成溶液,使用洒水壶将该溶液均匀喷洒至小区内,对照小区内喷洒等量水。
2019年8月中旬采集土壤样品,每个小区依照“S”形采集10个点的土样混合均匀,采样深度为0~10 cm。去除植物根系及其他土壤入侵物后,置于阴凉通风处风干,用于土壤基本理化性质、碳组分的测定。
凋落物和生物量于8月中下旬进行调查。每个试验小区放置1个1 m×1 m的样方,选择具有代表性的样方同时避免小区的边缘效应,采用收获法进行,将样方内植物分物种齐地面刈割后带回室内,凋落物则采集地上表面枯落的植物残体,最后在75℃烘箱烘至恒重后称量。
土壤理化及凋落物碳氮的测定[
土壤有机碳组分测定:采用H2SO4浸提法[
氮素添加处理的土壤活性有机碳敏感指数(sensitivity index,SI)计算公式[
采用单因素方差分析(One-way ANOVA)和邓肯(Duncan)法对不同处理进行差异显著性分析;利用R语言lavaan包建立结构方程模型,分析氮输入对土壤碳库的驱动途径。数据分析处理与作图使用Excel 2003、SigmaPlot 12.5,方差分析使用SPSS 19.0软件。
长期氮素添加下土壤有机碳(SOC)含量和RP-C含量与N0相比,各处理间差异均未达到显著水平(
长期氮素添加下土壤有机碳与惰性碳含量变化
Changes of soil organic carbon and recalcitrant carbon content under long-term nitrogen addition.
土壤活性碳组分对不同水平氮素添加的响应不同,由
长期氮素添加土壤活性碳组分含量变化
Changes of labile carbon fractions in soil with long-term nitrogen addition
土壤总活性有机碳占总有机碳的比例即为有机碳活性指数。由
长期氮素添加土壤有机碳指数变化
Changes of soil organic carbon index under long-term nitrogen addition
有机碳敏感度指数(SI)可指示土壤中对氮素添加措施反应较灵敏的有机碳组分。由
长期氮素添加活性碳组分敏感指数变化
Changes of sensitivity index of labile carbon fraction with long-term nitrogen addition
长期氮素添加对草甸草原土壤理化性质产生不同的影响。由
长期氮素添加土壤理化性质变化
Changes in soil physicochemical properties with long-term nitrogen addition
处理 |
pH | 土壤含水量①/(g·kg–1) | 全氮②/(g·kg–1) | 有效磷③/(mg·kg–1) | 速效钾④/(mg·kg–1) | 铵态氮⑤/(mg·kg–1) | 硝态氮⑥/(mg·kg–1) | 土壤碳氮比⑦ |
注:同列不同小写字母表示各处理有显著差异( |
||||||||
N0 | 7.13±0.16a | 33.64±1.12a | 2.60±0.02b | 9.21±1.05ab | 172.70±8.07a | 24.72±0.69e | 3.23±0.14e | 11.50±0.35b |
N15 | 6.60±0.03b | 27.19±1.58ab | 2.50±0.17b | 9.67±1.17a | 149.40±12.99a | 25.89±0.78e | 4.36±0.13e | 12.02±0.64b |
N30 | 6.62±0.06b | 28.14±0.53ab | 2.39±0.14b | 6.75±0.14ab | 148.82±11.34a | 32.33±1.26d | 4.45±0.04e | 12.43±0.85ab |
N50 | 6.67±0.09b | 29.11±1.86ab | 2.44±0.05b | 5.80±0.80b | 155.45±4.60a | 45.79±1.25b | 5.82±0.98e | 12.44±0.21ab |
N100 | 6.39±0.08b | 26.75±0.88ab | 2.51±0.14b | 9.93±2.41a | 172.70±9.29a | 50.40±1.15a | 13.36±0.54d | 12.93±0.96ab |
N150 | 5.86±0.07c | 23.39±2.68b | 2.78±0.05ab | 6.59±0.62ab | 174.02±13.07a | 36.33±1.01c | 40.48±0.74c | 15.62±2.34a |
N200 | 5.63±0.15c | 30.38± 3.28ab | 2.81±0.25ab | 7.06±0.58ab | 181.98±30.51a | 33.57±0.61cd | 52.27±0.98b | 11.65±1.62b |
N300 | 5.23±0.06d | 26.74±0.94ab | 3.33±0.42a | 7.67±0.73ab | 172.70±11.57a | 32.06±0.85d | 68.04±1.83a | 11.21±0.27b |
贝加尔针茅草原植被受长期氮素添加影响,其生物量发生显著变化(
长期氮素添加下植被生物量及凋落物性质变化
Changes in vegetation biomass and litter properties under long-term nitrogen addition
处理 |
地上生物量 |
地下生物量 |
凋落物碳 |
凋落物氮 |
凋落物碳氮比 |
N0 | 159.2±30.4c | 838.8±81.7d | 28.50±1.21c | 1.56±0.15ab | 18.84±2.11c |
N15 | 184.2±30.1bc | 929.5±39.2d | 30.74±0.12abc | 1.60±0.2ab | 20.18±2.74c |
N30 | 232.0±39.1ab | 866.2±64.97d | 33.63±0.94ab | 1.93±0.08a | 17.60±1.19c |
N50 | 237.6±14.6ab | 1 147.5±215.4c | 36.46±1.65a | 1.84±0.18a | 20.83±3.29c |
N100 | 243.8±28.1ab | 1 200.8±79.1c | 34.31±0.85ab | 1.90±0.07a | 18.04±0.32c |
N150 | 283.5±13.9a | 1 586.3±44.3b | 33.17±1.64abc | 1.36±0.08ab | 24.78±2.60ab |
N200 | 262.8±38.5a | 1 456.4±171.1b | 35.33±4.72ab | 1.08±0.10b | 27.75±3.80a |
N300 | 277.6±67.4a | 1 973.4±108.7a | 31.95±0.31abc | 1.38±0.21ab | 24.48±3.00ab |
结构方程模型(SEM)(
氮输入对土壤有机碳组分的作用途径(左:氮输入对土壤不同碳组分直接和间接影响;右:结构方程模型标准化总效应)
Effect of nitrogen input on soil organic carbon components(Left: The direct and indirect effects of nitrogen input on different soil carbon components; Right: The total effect of structural equation model standardization)
土壤碳循环作为陆地碳循环的重要组成部分,与陆地氮循环紧密耦合,土壤有机碳及其组分随着土壤中可利用氮的不断积累表现出不同的响应。本研究表明,不同水平的氮素添加下SOC与RP-C含量均未出现显著变化(
LPⅠ-C和LPⅡ-C在氮素添加下均有不同程度的增加,在N30和N100处理显著增加,且在N15~N50处理下土壤LPⅠ-C所占总活性碳的比例高于LPⅡ-C,在N100~N300处理下LPⅡ-C高于LPⅠ-C(
有机碳敏感指数可用来确定对不同氮素添加反应敏感的土壤碳组分,本研究结果表明土壤活性碳组分中的MBC对长期氮素添加的响应最为敏感(
贝加尔针茅草甸草原属于氮限制陆地生态系统,对氮素添加响应敏感[
草甸草原生态系统土壤碳氮循环紧密耦合,氮的持续输入对土壤有机碳的固存与分解产生影响,目前基于氮输入对环境因子的改变,提出“共代谢”与“养分挖掘”两种机制[
长期的氮素添加对贝加尔针茅草甸草原土壤有机碳及RP-C含量无显著影响,但对土壤碳组分含量的影响有所不同。LP-C在N30和N100处理显著增加,EOC无显著变化,MBC与DOC随氮素添加显著变化,拐点分别出现在N30与N100处理,说明相比于其他处理,土壤活性有机碳组分在N30~N100处理响应敏感;且通过SI指数可知,MBC对长期氮素添加响应更为敏感,能够有效反映长期氮素添加对贝加尔针茅草原土壤碳的影响,可作为本区域有机碳变化的指示碳组分。此外,长期氮素添加通过提高植被生物量与降低土壤pH对土壤有机碳及其组分产生正负效应,二者相互作用,共同调控着贝加尔针茅草甸草原土壤有机碳及其组分的含量变化。
Wen Z, Xu W, Li Q, et al. Changes of nitrogen deposition in China from 1980 to 2018. Environment International[J], 2020, 144: 106022.
Gu F X, Huang M, Zhang Y D, et al. Modeling the temporal-spatial patterns of atmospheric nitrogen deposition in China during 1961—2010[J]. Acta Ecologica Sinica, 2016, 36(12): 3591—3600.
顾峰雪, 黄玫, 张远东, 等. 1961—2010年中国区域氮沉降时空格局模拟研究[J]. 生态学报, 2016, 36(12): 3591—3600.
Wim D V. Impacts of nitrogen emissions on ecosystems and human health: A mini review[J]. Current Opinion in Environmental Science & Health
Zhu J X, Chen Z, Wang Q F, et al. Potential transition in the effects of atmospheric nitrogen deposition in China[J]. Environmental Pollution, 2020, 258: 113739.
Qiu Q Y, Bender S F, Mgelwa A S, et al. Arbuscular mycorrhizal fungi mitigate soil nitrogen and phosphorus losses: A meta-analysis[J]. Science of the Total Environment, 2021, 807: 150857.
Xu Z W, Ren H Y, Li M H, et al. Environmental changes drive the temporal stability of semi-arid natural grasslands through altering species asynchrony[J]. Journal of Ecology, 2015, 103(5): 1308—1316.
Schulte-Uebbing L, de Vries W. Global-scale impacts of nitrogen deposition on tree carbon sequestration in tropical, temperate, and boreal forests: A meta-analysis[J]. Global Change Biology, 2018, 24(2): 416—431.
Li F Q. Effects of crops and fertilization on soil aggregate size distribution and microbial communities and microbiological mechanisms in soil aggregate formation[D]. Nanjing: Nanjing Agricultural University, 2018.
李凤巧. 作物及施肥对土壤团聚体和微生物种群的影响及团聚体形成的微生物学机制研究[D]. 南京: 南京农业大学, 2018.
Perring M P, Bernhardt-Rӧmermann M, Baeten L, et al. Global environmental change effects on plant community composition trajectories depend upon management legacies[J]. Global Change Biology, 2018, 24(4): 1722—1740.
Xu C H, Xu X, Ju C H, et al. Long-term amplified responses of soil organic carbon to nitrogen addition worldwide[J]. Global Change Biology, 2021, 27(6): 1170—1180.
Li J H, Zhang R, Cheng B H, et al. Effects of nitrogen and phosphorus additions on decomposition and accumulation of soil organic carbon in alpine meadows on the Tibetan Plateau[J]. Land Degradation & Development, 2020, 32(3): 1467—1477.
Xu J H, Gao L, Sun Y, et al. Distribution of mineral-bonded organic carbon and black carbon in forest soils of Great Xing'an Mountains, China and carbon sequestration potential of the soils[J]. Acta Pedologica Sinica, 2018, 55(1): 236—246.
徐嘉晖, 高雷, 孙颖, 等. 大兴安岭森林土壤矿物结合态有机碳与黑碳的分布及土壤固碳潜力[J]. 土壤学报, 2018, 55(1): 236—246.
Tan Z X, Lal R, Izaurralde C, et al. Blochemically protected soil organic carbon at the north appalachina experimental watershed[J]. Soil Science, 2004, 169(6): 423—433.
Wiesmeier M, Urbanski L, Hobley E, et al. Soil organic carbon storage as a key function of soils - A review of drivers and indicators at various scales[J]. Geoderma, 2019, 333: 149—162.
Gong G R, Zhu C C, Yang L L, et al. Effects of nitrogen addition on above-and belowground litter decomposition and nutrient dynamics in the litter-soil continuum in the temperate steppe of Inner Mongolia, China[J]. Journal of Arid Environments, 2020, 172: 104036.
Zhao W Y G, Hong M, De H S, et al. Effects of long-term different nitrogen addition levels on plant community structure[J]. Acta Botanica Boreali-Occidentalia Sinica, 2020, 40(1): 141—149.
赵乌英嘎, 红梅, 德海山, 等. 长期不同施氮水平对草原植物群落结构的影响[J]. 西北植物学报, 2020, 40(1): 141—149.
Wu Z D, Hong M, Ma S F, et al. Effects of long-term nutrient addition on meso-micro soil arthropod communities in a
武振丹, 红梅, 马尚飞, 等. 长期养分添加对贝加尔针茅草原中小型土壤节肢动物群落的影响[J]. 应用与环境生物学报, 2022, 28(6): 1534—1541.
Bao S D. Soil and agricultural chemistry analysis[M]. Beijing: China Agriculture Press, 2000.
鲍士旦. 土壤农化分析[M]. 北京: 中国农业出版社, 2000.
Wu C J, Guo J F, Xu E L, et al. Effects of logging residue on composition of soil carbon and activity of related enzymes in soil of a young Chinese fir plantation as affected by residue handling mode[J]. Acta Pedologica Sinica, 2019, 56(6): 1504—1513.
吴传敬, 郭剑芬, 许恩兰, 等. 采伐残余物不同处理方式对杉木幼林土壤有机碳组分和相关酶活性的影响[J]. 土壤学报, 2019, 56(6): 1504—1513.
Wang X, Zhong Z K, Wang J Y, et al. Responses of soil carbon pool of abandoned grassland on the Loess Plateau to two-years warming and increased precipitation[J]. Acta Pedologica Sinica, 2023, 60(2): 523—534.
王兴, 钟泽坤, 王佳懿, 等. 黄土高原撂荒草地土壤碳库对两年增温增雨的响应[J]. 土壤学报, 2023, 60(2): 523—534.
Chen T, Hao X H, Du L J, et al. Effects of long-term fertilization on paddy soil organic carbon mineralization[J]. Chinese Journal of Applied Ecology, 2008, 19(7): 1494—1500.
陈涛, 郝晓晖, 杜丽君, 等. 长期施肥对水稻土土壤有机碳矿化的影响[J]. 应用生态学报, 2008, 19(7): 1494—1500.
Riggs C E, Hobbie S E, Bach E M, et al. Nitrogen addition changes grassland soil organic matter decomposition[J]. Biogeochemistry, 2015, 125(2): 203—219.
Jilling A, Keiluweit M, Gutknecht J L M, et al. Priming mechanisms providing plants and microbes access to mineral-associated organic matter[J]. Soil Biology and Biochemistry, 2021, 158: 108265.
Ma S F, Hong M, Zhao B Y N M L, et al. Effects of simulated nitrogen deposition on meso-micro soil fauna communities in meadow steppe[J]. Soils, 2021, 53(4): 755—763.
马尚飞, 红梅, 赵巴音那木拉, 等. 模拟氮沉降对草甸草原中小型土壤节肢动物群落的影响[J]. 土壤, 2021, 53(4): 755—763.
Keiluweit M, Bougoure J J, Nico S P, et al. Mineral protection of soil carbon counteracted by root exudates[J]. Nature Climate Change, 2015, 5(6): 588—595.
Wang X, Wang M, Tao Y M, et al. Beneficial effects of nitrogen deposition on carbon and nitrogen accumulation in grasses over other species in Inner Mongolian grasslands[J]. Global Ecology and Conservation, 2021, 26: e01507.
Shen T Y. Nitrogen and phosphorus inputs affect phusical protection and chemical stability of soil organic carbon in an alpine meadow on the Qinghai-Tibet Plateau[D]. Nanjing: Nanjing Agricultural University, 2018.
沈酊宇. 氮磷添加对青藏高原高寒草甸土壤有机碳物理保护和化学稳定性的影响[D]. 南京: 南京农业大学, 2018.
Liu X Q. Effects of drought and nitrogen deposition on soil properties of typical steppe in Inner Mongolia[D]. Huhhot: Inner Mongolia University, 2021.
刘星霁. 干旱与氮沉降对内蒙古典型草原土壤特性的影响[D]. 呼和浩特: 内蒙古大学, 2021.
Liang C, Zhu X F. The soil microbial carbon pump as a new concept for terrestrial carbon sequestration[J]. Science China(Earth Sciences), 2021. 64(4): 545—558.
Liang C, Schimel J P, Jastrow J D. The importance of anabolism in microbial control over soil carbon storage[J]. Nature Microbiology, 2017, 2: 17105.
Yue K X, Gong J R, Yu S Y, et al. Effects of litter quality and soil enzyme activity on litter decomposition rate in typical grassland subject to nitrogen addition[J]. Acta Prataculturae Sinica, 2020, 29(6): 71—82.
岳可欣, 龚吉蕊, 于上媛, 等. 氮添加下典型草原凋落物质量和土壤酶活性对凋落物分解速率的影响[J]. 草业学报, 2020, 29(6): 71—82.
Zhang M Y. Effect of nitrogen and litter addition on soil organic carbon pool components in Minjiang River estuary wetland[D]. Fuzhou: Fujian Normal University, 2019.
张美颖. 氮和枯落物添加对闽江河口湿地土壤有机碳库组分的影响[D]. 福州: 福建师范大学, 2019.
Sparling G P. Ratio of microbial biomass carbon to soil organic carbon as a sensitive indicator of changes in soil organic matter[J]. Australian Journal of Soil Research, 1992, 30: 195—207.
He P, Li Y, Jiang M J, et al. Effects of 14-year continuous nitrogen addition on soil carbon and nitrogen composition and physical structure at different depths in a typical temperate steppe[J]. Acta Ecologica Sinica, 2021, 41(5): 1808—1823.
贺佩, 李悦, 江明兢, 等. 连续氮添加14年对温带典型草原土壤碳氮组分及物理结构的影响[J]. 生态学报, 2021, 41(5): 1808—1823.
Carney K M, Hungate B A, Drake B G, et al. Altered soil microbial community at elevated CO2 leads to loss of soil carbon[J]. Proceedings of the National Academy of Sciences of the United States of America, 2007, 104(12): 4990—4995.
Ye C L, Chen D M, Hall J S, et al. Reconciling multiple impacts of nitrogen enrichment on soil carbon: Plant, microbial and geochemical controls[J]. Ecology Letters, 2018, 21(8): 1162—1173.
Tushar C S, Guido I, Riccardo S, et al. Linking organic matter chemistry with soil aggregate stability: Insight from 13C NMR spectroscopy[J]. Soil Biology and Biochemistry, 2018, 117: 175—184.
Chen R R, Senbayram M, Blagodatsky S, et al. Soil C and N availability determine the priming effect: Microbial N mining and stoichiometric decomposition theories[J]. Global Chang Biology, 2014, 20: 2356—2367.