青藏高原高寒草甸不同退化阶段植物氮利用速率变化

doi:10.11686/cyxb2024103

摘要/Abstract

摘要：

氮（N）是植物生长繁殖的必需元素，以多种形式存在于生态系统中。高寒草甸位置特殊，气候严酷，土壤有效氮匮乏。过度放牧引起草甸发生退化演替，土壤速效养分流失严重，导致植物的氮素利用模式发生改变。以青海省黄南州泽库县高寒草甸为研究对象，选取轻度、中度、重度退化、侵蚀、严重侵蚀以及黑土滩6个退化阶段，利用稳定性同位素¹⁵N示踪的方法量化小嵩草对铵态氮（NH₄⁺-N）和硝态氮（NO₃^--N）^{吸收速率沿不同退化阶段的变化，以及草甸退化后期多度较高物种：小嵩草、橐吾、香薷对无机氮利用的差异。结果表明：沿退化序列，小嵩草对总无机氮的吸收速率呈波动下降趋势，其中对NH₄⁺-N的吸收速率同总无机氮的吸收速率变化趋势一致，对NO₃^--N的吸收速率呈波动上升趋势。除侵蚀和黑土滩阶段外，小嵩草对NH₄⁺-N的吸收速率均为地下器官显著高于地上器官；除重度退化和黑土滩阶段外，其他阶段小嵩草对NO₃^--N的吸收速率均为地下器官显著高于地上器官。退化后期，小嵩草在嵩草占优势斑块和杂草占优势斑块中对NO₃^--N吸收方式无显著差异，而其在杂草占优势的斑块中对NH₄⁺-N的吸收速率显著高于嵩草占优势的斑块。杂草斑块中的优势植物橐吾和香薷对NH₄⁺-N和NO₃^--N吸收方式差异显著，橐吾对NH₄⁺-N的吸收速率显著高于NO₃^--N，而香薷对二者的吸收速率无显著差异。综上，在高寒草甸不同退化阶段，植物物种采用不同的无机氮获取策略适应土壤养分状况，维持自身生存。深入认识草地不同退化阶段植物对土壤无机氮素的吸收利用能够深入理解物种共存机制，进而指导退化草地的合理恢复。}

关键词: 高寒草甸, 退化序列, 无机氮的不同化学形态, 氮吸收速率, ¹⁵N示踪技术

Abstract:

Nitrogen （N） is an essential element for plant growth and reproduction， and it exists in various chemical forms in soils. The location of alpine meadows on the Tibetan Plateau is unique， where the climate is severe with low temperature. The low temperature restricts decomposition of soil organic matter and leads to scare available N in the soil， which further limits plant growth. Moreover， overgrazing causes grassland degradation and succession， resulting in severe loss of available nutrients in soil and changes in the N use patterns of plants. In this study， a ¹⁵N labeling experiment was conducted in an alpine meadow in Zeku County， Qinghai Province to trace plant utilization of ammonium nitrogen （NH₄⁺-N） and nitrate nitrogen （NO₃^--N） in plant communities exhibiting different degradation stages. Six degradation stages， including lightly， moderately， and severely degraded grasslands， and eroded， severely eroded grasslands， and bare black soil， were selected based on prior knowledge on plant community succession during the degradation of the alpine meadows. The uptake rates of NH₄⁺-N and NO₃^--N by the dominant sedge species Kobresia pygmaea were measured in the six degradation stages. Additionally， we also quantified the uptake rates of NH₄⁺-N and NO₃^--N by forb species Ligularia sibirica and Elsholtzia ciliata， the dominant species in patches in the later degradation stages. The results showed that along the degradation stages， the uptake rate of total inorganic nitrogen by K. pygmaea showed a fluctuating downward trend. The uptake rate of ammonium nitrogen was consistent with the trend of total inorganic nitrogen uptake rate， while the uptake rate of nitrate nitrogen showed a fluctuating upward trend. Except for the erosion and bare black soil stages， the uptake rate of ammonium nitrogen by K. pygmaea is significantly higher in underground organs than in aboveground organs. Except for the severe degradation and bare black soil stages， the uptake rate of nitrate nitrogen by K. pygmaea in underground organs was significantly higher than that in aboveground organs in all other stages. In the later stage of degradation， there was no significant difference in the uptake mode of nitrate nitrogen between patches dominated by K. pygmaea or patches dominated by forb species. However， the uptake rate of ammonium nitrogen was significantly higher in the patches dominated by the forb species than in the patches dominated by K. pygmaea. In patches， the dominant forb species， L. sibirica and E. ciliata， have significant differences in the uptake of ammonium and nitrate nitrogen. L. sibirica has a significantly higher uptake rate of NH₄⁺-N than NO₃^--N， while E. ciliata has no significant difference in the uptake rate of the two inorganic N forms. In summary， at different stages of degradation in the alpine meadow， plant species adopt different inorganic nitrogen acquisition strategies to adapt to soil nutrient conditions， by which maintains plant species coexistence. A deeper understanding of the absorption and utilization of soil inorganic nitrogen by plants at different stages of grassland degradation can provide insight into the mechanisms of species coexistence and guide the restoration of degraded grasslands.

Key words: alpine meadow, degradation sequence, different chemical forms of inorganic nitrogen, nitrogen uptake rate, ¹⁵N tracing

霍佳娟, 宋明华. 青藏高原高寒草甸不同退化阶段植物氮利用速率变化[J]. 草业学报, 2025, 34(2): 16-26.

Jia-juan HUO, Ming-hua SONG. Changes in nitrogen uptake rate of plant species in different degradation stages of an alpine meadow on the Qinghai-Tibet Plateau[J]. Acta Prataculturae Sinica, 2025, 34(2): 16-26.

图/表 7

表1 不同植被斑块氮含量

Table 1 Nitrogen content of different vegetation patches

群落植被类型 Community vegetation type	总氮含量 Total nitrogen content （g·kg^-1）	铵态氮含量 NH₄⁺-N content （mg·kg^-1）	硝态氮含量 NO₃^--N content （mg·kg^-1）
轻度退化小嵩草占优势群落Light degraded K. pygmaea dominant community	4.95	17.12	1.40
中度退化小嵩草占优势群落Moderate degraded K. pygmaea dominant community	7.77	13.75	2.90
重度退化杂草斑块Severe degraded forb patch	6.78	21.19	1.51
重度退化小嵩草斑块Severe degraded K. pygmaea patch	5.96	20.97	1.19
侵蚀杂草斑块Erode degraded forb patch	3.87	21.23	2.83
侵蚀小嵩草斑块Erode degraded K. pygmaea patch	5.42	18.34	2.19
严重侵蚀杂草斑块Severe erosion forb patch	5.09	22.33	1.57
严重侵蚀小嵩草斑块Severe erosion K. pygmaea patch	5.42	23.34	1.55
黑土滩杂草斑块Bare forb patch	3.80	14.45	2.34
黑土滩小嵩草斑块Bare K. pygmaea patch	3.69	11.35	1.94

表2 高寒草甸退化序列划分标准

Table 2 Division principle of degradation sequence of alpine meadow

退化序列Degenerate sequence	划分标准Division principle
轻度退化Light degraded	植被覆盖约80%，伴随些许鼠洞。Vegetation coverage is approximately 80%，with the presence of a small number of rodent burrows.
中度退化Moderate degraded	植被覆盖度大于60%，鼠洞增加，草皮未开裂。Vegetation coverage exceeds 60%，with an increase in rodent burrows and the turf remaining uncracked.
重度退化Severe degraded	植被覆盖度达50%，草皮开裂，斑块显现。Vegetation coverage reaches 50%， with turf cracking and patches becoming apparent.
侵蚀Erode degraded	裸地和斑块增加，开裂程度大于5 cm。Bare ground and patches increase， with crack width exceeding 5 cm.
严重侵蚀Severe erosion	裸地面积增加，大于植被斑块面积，开裂加深。Bare ground area increases， surpassing the area of vegetation patches， with deepening cracks.
黑土滩Bare	杂草和裸地面积占主要，伴随少数或没有嵩草秃斑，植物物种单一。Dominated by weeds and bare ground， minimal tall grass， and low species diversity.

图1 不同形态氮素总吸收速率沿退化演替进程变化LD：轻度退化 Light degraded； ZD：中度退化 Moderate degraded； ZHD：重度退化 Severe degraded； QS：侵蚀 Erode degraded； YQ：严重侵蚀 Severe erosion； HT：黑土滩 Bare. 不同小写字母表示不同退化阶段间差异显著（P<0.05）。Different lowercase letters indicate significant differences among different stages of degradation. 下同 The same below.

Fig.1 The total uptake rate of different forms of nitrogen changed along the degradation succession process

图2 各演替阶段不同形态氮素地上地下吸收速率对比不同小写字母代表同一退化阶段下地上部分与地下部分差异显著（P<0.05）。Different lowercase letters represent significant differences between aboveground and underground under the same succession stage （P<0.05）.

Fig.2 Comparison of aboveground and underground uptake rates of different forms of inorganic nitrogen with different succession stages

图3 退化演替进程中植物相对氮形态偏好不同小写字母代表不同退化阶段下各指标间差异显著（P<0.05）。Different lowercase letters represent significant differences among different degradation stages （P<0.05）.

Fig.3 Relative N form preference of plant with the process of degradation succession

图4 不同类型斑块小嵩草氮吸收速率对比不同小写字母代表同一退化阶段不同斑块间差异显著（P<0.05）。Different lowercase letters represent significant differences between different patchs under the same degradation stage （P<0.05）.

Fig.4 Comparison of nitrogen uptake rate of K. pygmaea under different types of patches

图5 退化后期优势杂草氮吸收速率对比图a， b中不同小写字母表示不同氮素形式间差异显著（P<0.05）。图c， d中不同小写字母表示同一氮素形式不同部位间差异显著（P<0.05）。In figure a and b， different lowercase letters indicate significant differences between different nitrogen forms （P<0.05）. In figure c and d， different lowercase letters indicate significant differences between different positions of the same nitrogen form （P<0.05）.

Fig.5 Comparison of nitrogen uptake rate of dominant species in the later stage of degradation

参考文献 28

1	Zhang S H， Zhang Y， Ma X Y， et al. Mechanisms underlying loss of plant biodiversity by atmospheric nitrogen deposition in grassland. Acta Ecologica Sinica， 2022， 42（4）： 1252-1261.
	张世虎，张悦，马晓玉，等. 大气氮沉降影响草地植物物种多样性机制研究综述. 生态学报， 2022， 42（4）： 1252-1261.
2	Zhang Y X， Yao T， Wang G J， et al. Characteristics of vegetation and soil inorganic nitrogen concentrations under different disturbed habitats in a weak alpine ecosystem. Acta Prataculturae Sinica， 2014， 23（4）： 245-252.
	张玉霞，姚拓，王国基，等. 高寒生态脆弱区不同扰动生境草地植被及土壤无机氮变化特征. 草业学报， 2014， 23（4）： 245-252.
3	Wang W Y， Ma Y G， Xu J， et al. The uptake diversity of soil nitrogen nutrients by main plant species in Kobresia humilis alpine meadow on the Qinghai-Tibet Plateau. Science China， Earth Science， 2012， 42（8）： 1264-1272.
	王文颖，马永贵，徐进，等.高寒矮嵩草（Kobresia humilis）草甸植物吸收土壤氮素的多元化途径研究. 中国科学：地球科学， 2012， 42（8）： 1264-1272.
4	Wang W Y， Zhou H K， Yang L， et al. The uptake strategy of soil nitrogen nutrients by different plant species in alpine Kobresia tibetica meadow on the Qinghai-Tibet Plateau. Journal of Natural Resources， 2014， 29（2）： 249-255.
	王文颖，周华坤，杨莉，等.高寒藏嵩草（Kobresia tibetica）草甸植物对土壤氮素利用的多元化特征. 自然资源学报， 2014，29（2）： 249-255.
5	Andrews M， Raven J A， Lea P J. Do plants need nitrate？ The mechanisms by which nitrogen form affects plants. Annals of Applied Biology， 2013， 163（2）： 174-199.
6	Raab T K， Monson L. Soil amino acid utilization among species of the cyperaceae： plant and soil processes. Ecology， 1999， 80（7）： 2408-2419.
7	Wang C H， Xing X R， Han X G. Advances in study of factors affecting soil N mineralization in grassland ecosystems. Chinese Journal of Applied Ecology， 2004（11）： 2184-2188.
	王常慧，邢雪荣，韩兴国. 草地生态系统中土壤氮素矿化影响因素的研究进展. 应用生态学报， 2004（11）： 2184-2188.
8	Rennenberg H， Dannenmann M， Gessler A， et al. Nitrogen balance in forest soils： nutritional limitation of plants under climate change stresses. Plant Biology， 2010， 11（S1）： 4-23.
9	Cao Y Z. The effects of simulated desertification on dominant plant species growth and nutrient uptake in Horqin grassland. Shenyang： Shenyang University， 2020.
	曹彦卓. 模拟沙化对科尔沁草地优势植物生长及养分吸收的影响. 沈阳：沈阳大学， 2020.
10	Xu L H， Yao B Q， Wang W Y， et al. Nitrogen absorption and distribution characteristics in different organs of the main plants in Kobresia humilis meadow. Acta Botanica Boreali-Occidentalia Sinica， 2018， 38（5）： 957-966.
	徐隆华，姚步青，王文颖，等. 矮嵩草草甸主要植物不同器官对氮素的吸收及分配特征研究. 西北植物学报， 2018， 38（5）： 957-966.
11	Du Y， Guo X， Geng Z， et al. Effect of grazing intensity on soil and plant δ¹⁵N of an alpine meadow. Polish Journal of Environmental Studies， 2017， 26（3）： 1071-1075.
12	Babel W， Biermann T， Coners H， et al. Pasture degradation modifies the water and carbon cycles of the Tibetan highlands. Copernicus Publications， 2014， 11（23）： 6633-6656.
13	Wang C T， Long R J， Wang Q L， et al. Changes in plant diversity， biomass and soil C， in alpine meadows at different degradation stages in the headwater region of Three Rivers， China. Land Degradation & Development， 2009， 20（2）： 187-198.
14	Cui S， Meng F， Suonan J， et al. Responses of phenology and seed production of annual Koenigia islandica to warming in a desertified alpine meadow. Agricultural and Forest Meteorology， 2017， 247： 376-384.
15	Harrison K A， Bardgett B R D. Preferences for different nitrogen forms by coexisting plant species and soil microbes. Ecology， 2007， 88（4）： 989-999.
16	Nordin A， Schmidt I K， Schmidt G R， et al. Nitrogen uptake by arctic soil microbes and plants in relation to soil nitrogen supply. Ecology， 2004， 85（4）： 955-962.
17	Chapin F S， Moilanen L， Kielland K. Preferential use of organic nitrogen for growth by a non-mycorrhizal arctic sedge. Nature， 1993， 361（6408）： 150-153.
18	Pang Z， Jiang L， Wang S， et al. Differential response to warming of the uptake of nitrogen by plant species in non-degraded and degraded alpine grasslands. Journal of Soils and Sediments， 2019， 19（5）： 2212-2221.
19	Zhou C L， Li Y K， Cao G M， et al. Carbon and nitrogen stable isotopes technology in the researches on alpine meadow ecosystem in Qinghai-Tibet Plateau： Progress and prospect. Chinese Journal of Applied Ecology， 2020， 31（10）： 3568-3578.
	周春丽，李以康，曹广民，等. 碳氮稳定同位素技术在青藏高原高寒草甸生态系统研究中的应用：进展与展望. 应用生态学报， 2020， 31（10）： 3568-3578.
20	Kang Q. The study on soil nitrogen dynamics and the uptake of alpine plant species to soil resolved nitrogen in alpine grassland. Xining： Qinghai Normal University， 2016.
	康清. 高寒草地土壤氮素及高寒牧草对土壤氮素吸收特征研究. 西宁：青海师范大学， 2016.
21	Wei Q. The effects of fertilizer and water additions on main plants n absorption and utilization stand in Kobresia humilis meadow based on ¹⁵N isotope labeled. Xining： Qinghai Normal University， 2014.
	魏晴. 利用δ¹⁵N同位素示踪技术研究矮嵩草草甸主要植物种氮素吸收利用对水肥添加的响应. 西宁：青海师范大学， 2014.
22	Ma Y S， Lang B N， Li Q Y， et al. Study on rehabilitating and rebuilding technologies for degenerated alpine meadow in the Changjiang and Yellow river source region. Practacultural Science， 2002， 19（9）： 1-5.
	马玉寿，郎百宁，李青云，等. 江河源区高寒草甸退化草地恢复与重建技术研究. 草业科学， 2002， 19（9）： 1-5.
23	Liu M， Adl S， Cui X， et al. In situ methods of plant-microbial interactions for nitrogen in rhizosphere. Rhizosphere， 2020， 13： 100186.
24	Paul D， Skrzypek G， Fórizs I. Normalization of measured stable isotopic compositions to isotope reference scales-A review. Rapid Communications in Mass Spectrometry Rcm， 2007， 21（18）： 3006-3014.
25	Fang Y T， Mo J M， Per G， et al. Nitrogen transformations in forest soils and its responses to atmospheric nitrogen deposition： A review. Acta Ecologica Sinica， 2004， 24（7）： 1523-1531.
	方运霆，莫江明， Per Gundersen，等. 森林土壤氮素转换及其对氮沉降的响应. 生态学报， 2004， 24（7）： 1523-1531.
26	Raab T K， Lipson D A， Monson R K. Non-mycorrhizal uptake of amino acids by roots of the alpine sedge Kobresia myosuroides： Implications for the alpine nitrogen cycle. Oecologia， 1996， 108（3）： 488-494.
27	Ashton I W， Miller A E， Bowman W D， et al. Niche complementarity due to plasticity in resource use： Plant partitioning of chemical N forms. Ecology， 2010， 91（11）： 3252-3260.
28	Liang D F， Jiang H Y， Li H L. Effeets of Ligularia virgaurea on litter decomposition and nitrogen release in alpine meadow. Chinese Journal of Ecology， 2022， 41（5）： 895-902.
	梁德飞，蒋宏宇，李宏林. 黄帚橐吾对高寒草甸凋落物分解及氮释放的影响. 生态学杂志， 2022， 41（5）： 895-902.

[1]	和阳一丹, 陈昌明, 黄晓霞, 施国美, 和克俭. 川西高寒草甸植物功能属性与环境因子的关系研究[J]. 草业学报, 2024, 33(9): 28-39.
[2]	谭湘蛟, 董逵才, 张华, 唐川川, 杨燕. 积雪增加对青藏高原高寒草甸土壤磷有效性的影响[J]. 草业学报, 2024, 33(7): 205-214.
[3]	秦瑞敏, 程思佳, 马丽, 张中华, 魏晶晶, 苏洪烨, 史正晨, 常涛, 胡雪, 阿的哈则, 袁访, 李珊, 周华坤. 围封和施肥对高寒草甸群落特征和植被碳氮库的影响[J]. 草业学报, 2024, 33(4): 1-11.
[4]	油志远, 马淑娟, 王长庭, 丁路明, 宋小艳, 尹高飞, 毛军. 川滇高原高寒草甸生态系统不同功能群植物分布格局的MaxEnt模型预测[J]. 草业学报, 2024, 33(3): 1-12.
[5]	马源, 王晓丽, 马玉寿, 张德罡. 高寒草甸退化程度对优势物种根际土壤真菌群落和生态网络的影响[J]. 草业学报, 2024, 33(2): 125-137.
[6]	冯娅斯, 蒋文婷, 刘益宏, 王燕, 李渊, 陈有超, 蔡延江. 翻耕和植物残体覆盖对“黑土滩”型退化草地土壤氧化亚氮排放的影响[J]. 草业学报, 2024, 33(11): 15-29.
[7]	李林芝, 张德罡, 马源, 罗珠珠, 林栋, 海龙, 白兰鸽. 不同退化程度高寒草甸土壤团聚体养分及生态化学计量特征研究[J]. 草业学报, 2023, 32(8): 48-60.
[8]	廖小琴, 王长庭, 刘丹, 唐国, 毛军. 氮磷配施对高寒草甸植物根系特征的影响[J]. 草业学报, 2023, 32(7): 160-174.
[9]	路欣, 祁娟, 师尚礼, 车美美, 李霞, 独双双, 赛宁刚, 贾燕伟. 阔叶类草抑制剂与氮素配施对高寒草甸土壤特性的影响[J]. 草业学报, 2023, 32(7): 38-48.
[10]	刘彩凤, 段媛媛, 王玲玲, 王乙茉, 郭正刚. 高原鼠兔干扰对高寒草甸植物物种多样性与土壤生态化学计量比间关系的影响[J]. 草业学报, 2023, 32(6): 157-166.
[11]	孙玉, 杨永胜, 何琦, 王军邦, 张秀娟, 李慧婷, 徐兴良, 周华坤, 张宇恒. 三江源高寒草甸水源涵养功能及土壤理化性质对退化程度的响应[J]. 草业学报, 2023, 32(6): 16-29.
[12]	周娟娟, 刘云飞, 王敬龙, 魏巍. 短期养分添加对西藏沼泽化高寒草甸地上生物量、植物多样性和功能性状的影响[J]. 草业学报, 2023, 32(11): 17-29.
[13]	游郭虹, 刘丹, 王艳丽, 王长庭. 高寒草甸植物叶片生态化学计量特征对长期氮肥添加的响应[J]. 草业学报, 2022, 31(9): 50-62.
[14]	张玉琢, 杨志贵, 于红妍, 张强, 杨淑霞, 赵婷, 许画画, 孟宝平, 吕燕燕. 基于STARFM的草地地上生物量遥感估测研究——以甘肃省夏河县桑科草原为例[J]. 草业学报, 2022, 31(6): 23-34.
[15]	李洋, 王毅, 韩国栋, 孙建, 汪亚峰. 青藏高原高寒草地土壤微生物量碳氮含量特征及其控制要素[J]. 草业学报, 2022, 31(6): 50-60.