Effects of Different Restoration Models on Soil Carbon and Nitrogen Stoichiometry in Junzhaigou Earthquake-stricken Landslides

XIAN Ting; DONG Tingfa; DENG Dongzhou; PAN Hongli; DIAO Yuanbin; LIU Yuping

doi:10.12172/202011080001

Volume 42 Issue 1

Feb. 2021

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Xian T, Dong T F, Deng D Z, et al. Effects of different restoration models on soil carbon and nitrogen stoichiometry in Junzhaigou earthquake-stricken landslides[J]. Journal of Sichuan Forestry Science and Technology, 2021, 42(1): 11−15 doi: 10.12172/202011080001

Citation:

Effects of Different Restoration Models on Soil Carbon and Nitrogen Stoichiometry in Junzhaigou Earthquake-stricken Landslides

doi: 10.12172/202011080001

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1.
College of Life Sciences, China West Normal University, Nanchong 637002, China
2.
Sichuan Key Laboratory of Ecological Restoration and Conservation for Forest and Wetland, Sichuan Academy of Forestry, Chengdu 610081, China

Corresponding author: dongzhoud@163.com
Received Date: 2020-11-08
Available Online: 2021-01-13
Publish Date: 2021-02-04

Abstract

According to the comparison of soil carbon and nitrogen stoichiometry characteristics between natural restoration after earthquake (NR), artificial restoration after earthquake (AR) and natural vegetation without earthquake (CK) in Jiuzhaigou country, it could provide theoretical basis for rapid restoration of landslide damaged by Jiuzhaigou earthquake. The results showed that: (1) Compared with the soil without earthquake damage, the contents of soil organic carbon (SOC), total nitrogen (TN), available nitrogen (AN) in landslides with earthquake-damaged vegetation were lower than that on CK, but the pH value and C/N were higher. (2) The total vegetation coverage, SOC, TN and AN contents under artificial restoration were higher than those under natural restoration. (3) SOC was positively correlated with TN or AN, but negatively correlated with pH or C/N. These short-term results indicated that artificial restoration was better for vegetation recovery of earthquake-stricken landslides than natural restoration. In addition, it is suggested that nitrogen-fixing plants should be planted in the future vegetation restoration.
- Carbon and nitrogen stoichiometry;
- Vegetation restoration;
- Jizhaigou;
- Landslide

References

[1]	贺金生,韩兴国. 生态化学计量学: 探索从个体到生态系统的统一化理论[J]. 植物生态学报,2010,34(1):2−6. doi: 10.3773/j.issn.1005-264x.2010.01.002
[2]	王绍强,于贵瑞. 生态系统碳氮磷元素的生态化学计量学特征[J]. 生态学报,2008,28(8):3937−3947. doi: 10.3321/j.issn:1000-0933.2008.08.054
[3]	张佳慧,王兴昌,王传宽. 帽儿山温带森林演替初期土壤碳、氮、磷计量特征的变化[J]. 应用生态学报,2016,27(10):3189−3195.
[4]	Xiong X, Zhang H, Deng Q, et al. Soil organic carbon turnover following forest restoration in south China: Evidence from stable carbon isotopes[J]. Forest Ecology and Management, 2020, 462: 117988. doi: 10.1016/j.foreco.2020.117988
[5]	Myers N, Mittermeier RA, Mittermeier CG, et al. Biodiversity hotspots for conservation priorities[J]. Nature, 2000, 403(6772): 853−858. doi: 10.1038/35002501
[6]	Lin W-T, Lin C-Y, Chou W-C. Assessment of vegetation recovery and soil erosion at landslides caused by a catastrophic earthquake: a case study in Central Taiwan[J]. Ecological Engineering, 2006, 28(1): 79−89. doi: 10.1016/j.ecoleng.2006.04.005
[7]	曾剑峰,罗鹏,牟成香,等. 岷山地震带山地坡面的植被演替[J]. 应用与环境生物学报,2014,20(1):1−7.
[8]	Ma H, Wang Y, Yue H, Zhong B. The threshold between natural recovery and the need for artificial restoration in degraded lands in Fujian Province, China[J]. Environmental Monitoring and Assessment, 2013, 185(10): 8639−8648. doi: 10.1007/s10661-013-3200-9
[9]	庞学勇,包维楷,江元明,等. 九寨沟和黄龙自然保护区原始林与次生林土壤物理性质比较[J]. 应用与环境生物学报,2009,15(6):768−773.
[10]	鲍士旦. 土壤农化分析[M]. 北京: 中国农业出版社, 2000.
[11]	Bing HJ, Wu YH, Zhou J, et al. Stoichiometric variation of carbon, nitrogen, and phosphorus in soils and its implication for nutrient limitation in alpine ecosystem of Eastern Tibetan Plateau[J]. Journal of Soils and Sediments, 2016, 16: 405−416. doi: 10.1007/s11368-015-1200-9
[12]	吴聪,王金牛,卢涛,等. 汶川地震对龙门山地区山地土壤理化性质的影响[J]. 应用与环境生物学报,2012,18(6):911−916.
[13]	Cookson WR, Abaye DA, Marschner P, et al. The contribution of soil organic matter fractions to carbon and nitrogen mineralization and microbial community size and structure[J]. Soil Biology and Biochemistry, 2005, 37(9): 1726−1737. doi: 10.1016/j.soilbio.2005.02.007
[14]	Zuo X, Zhao X, Zhao H, et al. Spatial heterogeneity of soil properties and vegetation–soil relationships following vegetation restoration of mobile dunes in Horqin Sandy Land, Northern China[J]. Plant and Soil, 2009, 318(1−2): 153−167. doi: 10.1007/s11104-008-9826-7
[15]	Hobbie SE, Gough L. Foliar and soil nutrients in tundra on glacial landscapes of contrasting ages in northern[J]. Oecologia, 2016, 131(3): 453−462.
[16]	Don A, Schumacher J, Scherer-Lorenzen M. Spatial and vertical variation of soil carbon at two grassland sites-implications for measuring soil carbon stocks[J]. Geoderma, 2007, 141(3−4): 272−282. doi: 10.1016/j.geoderma.2007.06.003
[17]	Tian HQ, Chen GS, Zhang C, et al. Pattern and variation of C: N: P ratios in China’s soils: A synthesis of observational data[J]. Biogeochemistry, 2010, 98: 139−151. doi: 10.1007/s10533-009-9382-0
[18]	Zhou W, Han G, Liu M, et al. Effects of soil pH and texture on soil carbon and nitrogen in soil profiles under different land uses in Mun River Basin, Northeast Thailand[J]. PeerJ, 2019, 7: e7880. doi: 10.7717/peerj.7880
[19]	Kemmitt SJ, Wright D, Goulding KW, et al. pH regulation of carbon and nitrogen dynamics in two agricultural soils[J]. Soil Biology and Biochemistry, 2006, 38(5): 898−911. doi: 10.1016/j.soilbio.2005.08.006
[20]	魏强,凌雷,柴春山,等. 甘肃兴隆山森林演替过程中的土壤理化性质[J]. 生态学报,2012,32(15):4700−4713.

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沈阳化工大学材料科学与工程学院沈阳 110142

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土壤养分作为陆地植物养分的主要来源，除了养分含量之外，养分间的平衡关系也是调控植物生长和分布的关键因子之一^[1]。生态化学计量学通过比较元素间的比例关系，为探究生态系统结构和功能的提供新的角度和方法^[2]。由于土壤碳(C)、氮(N)是植物演替早期最主要的元素，因而碳氮化学计量特征是影响陆地植被生态系统的演化与恢复关键因素之一^[3-4]。

九寨沟自然保护区作为世界自然遗产，是中国第一个以保护自然风景为主的自然保护区，也是全球生物多样性保护热点地区^[5]。2017年8月的7.0级地震导致了该地大量的土壤流失和植被摧毁等一系列生态环境问题。如何恢复受损的生态系统对其生物多样性的保护及生态旅游至关重要。地震所造成的滑坡体上植被的恢复为认识植被演替的调控因子提供了较好的模式^[6-7]。植被恢复主要通过自然恢复和人工恢复。一般而言，人工恢复模式因恢复时间快、景观效果好而受到欢迎，而在生物多样性保护和稳定性方面的价值却遭到了怀疑^[8]。因此，通过比较自然恢复和人工恢复下土壤碳氮化学计量特征的差异，探讨不同植被恢复方式对植被恢复的影响机理，以期为该地植被快速恢复提供理论依据。

1. 材料与研究方法

1.1. 研究地自然概况

九寨沟自然保护区位于四川省阿坝州九寨沟县(东经：100°30′—104°27′，北纬: 30°35′—34°19′)。地处青藏高原、川西高原、山地向四川盆地过渡地带。自然植被主要是上世纪60年代砍伐后的次生林，主要有云杉（Picea asperata）、红桦（Betula albosinensis）、槭树（Acer spp.）、花楸（Sorbus aucuparia）、高山柳（Salix cupularis）等。林下土壤为暗棕壤。年均气温7.1 ℃，最高温度30.3 ℃，最低温度−17 ℃，年降雨量696.6~957.5 mm，积雪期从10月至次年4月^[9]。地震后人工恢复2018年3月，方式为石笼挡土墙+铺草垫。

1.2. 样品采集及指标测定

选取了保护区的核心区域五花海和长海沟区域，海拔约3000 m。在震滑体及其附近的自然坡体为研究对象，依据样点具有典型性和代表性的原则，共选取了4个自然恢复、4个人工恢复及5个邻近对照坡体样点，每个样点1个10 m×10 m的样方估计植被的总盖度。坡度约为40°。自然植被、震后自然恢复、震后人工修复的土壤平均厚度分别约为20 cm、0.2 cm和1.0 cm。在每个坡体样方内按“S”形采样法采取土壤样品。取样深度为0~10 cm。采样前除去地表植被，分别装入密封样品袋中，统一编号并带回实验室，经自然风干，去除石块、根系等杂物后研磨过筛，供测定各项土壤指标。

土壤pH值的测量采用水浸提电位法，有机碳含量测定采用重铬酸钾氧化−外加热法，土壤全氮含量测定采用凯氏定氮法，可利用性氮含量测定采用碱解扩散法^[10]。

1.3. 数据分析

运用单因素方差分析检验植被总盖度、土壤pH、养分含量及其化学计量特征在不同植被恢复方式之间的差异(LSD检验)。Pearson检验(双尾)检验性状之间的相关性。数据分析在SPSS 22.0 (IBM, USA)下进行。

3. 讨论

调查发现，在震后两年多后，自然恢复的坡体上的一些零星的草本和灌木的先锋物种总盖度约占未受损植被盖度的15%，而震后进行的人工恢复的坡体上约占未受损植被盖度的40%。这短期的调查结果显示尽管九寨沟地震受损植被能进行一定程度的自然恢复，但人工的恢复措施大大提高了植被的盖度。土壤作为影响植被特征的核心因子^[11]。本研究发现受损坡体的土壤碳氮养分显著低于未受损植被的土壤，这与先前的一些结果一致^[12]。这主要是因为强烈地震导致的山体滑坡使得表层土壤流失。九寨沟地区本身土层就薄弱，尤其是一些坡度大于40°的坡体，地震后表层土壤消失，基本上形成了石漠化的土壤。这直接影响了土壤的理化特征。受损植被的土壤有机碳、总氮、可利用氮均小于未受损植被，且这些指标在自然恢复的土壤下最低。因为土壤有机碳主要来源于凋落物，一旦土壤有机碳缺乏，土壤微生物对氮素的矿化能力减弱，从而使土壤氮的含量不高^[13]。总体上来看，不同恢复方式下土壤养分结果与植被盖度的结果一致，这进一步证实了土壤养分与植被的紧密关系^[14]。

土壤化学计量特征作为养分限制的预测性指标^[15]。C∶N是土壤氮素矿化能力的标志，与土壤有机碳分解速率呈反比^[16]。本研究发现土壤C∶N均值为34.61，远高于中国陆地土壤C∶N均值（11.9±0.1）^[17]。同时C∶N在不同恢复方式下差异极大（从17.32到56.61），其中受损未恢复下的值最高，而未受损植被下的值最低。这主要的原因是震后的氮含量降低得比碳含量多。同时更高的C∶N暗示了该地有机碳分解慢，且氮比碳更为匮缺^[16]。众多研究表明，土壤养分及化学计量特征之间存在相关性^[11]^[3]。同时本研究中发现pH值与C/N呈现正相关，与土壤碳氮含量呈现负相关，这与Zhou等^[18]在其他地方的结果一致。这表明pH值适度的降低有利于凋落物的分解（通过提高土壤微生物的活性）和碳氮的积累^[19]。有机碳是土壤养分的重要来源，这也解释了其与全氮、可利用氮呈现显著的正相关关系，这反映了土壤碳氮之间的平衡与耦合机制^[20]，同时也说明了有机质在促进养分循环方面起着重要作用^[19]。

综上所述，本研究通过比较不同恢复方式土壤碳氮化学计量特征的差异，短期的结果显示人工恢复措施与自然恢复对九寨沟震后土壤碳氮含量及其化学计量特征差异明显。人工恢复下有机碳、总氮、可利用氮含量显著高于自然恢复，这些结果与植被盖度的结果一致。相比碳而言，氮对于该地的植被早期恢复的限制更大。建议在今后地恢复措施中应该多考虑固氮植物，以便更快速的恢复。当然，需要更大尺度（包括时间和其他养分）的研究来进一步验证这些结论。

Reference (20)

[1]	贺金生,韩兴国. 生态化学计量学: 探索从个体到生态系统的统一化理论[J]. 植物生态学报,2010,34(1):2−6.
[2]	王绍强,于贵瑞. 生态系统碳氮磷元素的生态化学计量学特征[J]. 生态学报,2008,28(8):3937−3947.
[3]	张佳慧,王兴昌,王传宽. 帽儿山温带森林演替初期土壤碳、氮、磷计量特征的变化[J]. 应用生态学报,2016,27(10):3189−3195.
[4]	Xiong X, Zhang H, Deng Q, et al. Soil organic carbon turnover following forest restoration in south China: Evidence from stable carbon isotopes[J]. Forest Ecology and Management, 2020, 462: 117988.
[5]	Myers N, Mittermeier RA, Mittermeier CG, et al. Biodiversity hotspots for conservation priorities[J]. Nature, 2000, 403(6772): 853−858.
[6]	Lin W-T, Lin C-Y, Chou W-C. Assessment of vegetation recovery and soil erosion at landslides caused by a catastrophic earthquake: a case study in Central Taiwan[J]. Ecological Engineering, 2006, 28(1): 79−89.
[7]	曾剑峰,罗鹏,牟成香,等. 岷山地震带山地坡面的植被演替[J]. 应用与环境生物学报,2014,20(1):1−7.
[8]	Ma H, Wang Y, Yue H, Zhong B. The threshold between natural recovery and the need for artificial restoration in degraded lands in Fujian Province, China[J]. Environmental Monitoring and Assessment, 2013, 185(10): 8639−8648.
[9]	庞学勇,包维楷,江元明,等. 九寨沟和黄龙自然保护区原始林与次生林土壤物理性质比较[J]. 应用与环境生物学报,2009,15(6):768−773.
[10]	鲍士旦. 土壤农化分析[M]. 北京: 中国农业出版社, 2000.
[11]	Bing HJ, Wu YH, Zhou J, et al. Stoichiometric variation of carbon, nitrogen, and phosphorus in soils and its implication for nutrient limitation in alpine ecosystem of Eastern Tibetan Plateau[J]. Journal of Soils and Sediments, 2016, 16: 405−416.
[12]	吴聪,王金牛,卢涛,等. 汶川地震对龙门山地区山地土壤理化性质的影响[J]. 应用与环境生物学报,2012,18(6):911−916.
[13]	Cookson WR, Abaye DA, Marschner P, et al. The contribution of soil organic matter fractions to carbon and nitrogen mineralization and microbial community size and structure[J]. Soil Biology and Biochemistry, 2005, 37(9): 1726−1737.
[14]	Zuo X, Zhao X, Zhao H, et al. Spatial heterogeneity of soil properties and vegetation–soil relationships following vegetation restoration of mobile dunes in Horqin Sandy Land, Northern China[J]. Plant and Soil, 2009, 318(1−2): 153−167.
[15]	Hobbie SE, Gough L. Foliar and soil nutrients in tundra on glacial landscapes of contrasting ages in northern[J]. Oecologia, 2016, 131(3): 453−462.
[16]	Don A, Schumacher J, Scherer-Lorenzen M. Spatial and vertical variation of soil carbon at two grassland sites-implications for measuring soil carbon stocks[J]. Geoderma, 2007, 141(3−4): 272−282.
[17]	Tian HQ, Chen GS, Zhang C, et al. Pattern and variation of C: N: P ratios in China’s soils: A synthesis of observational data[J]. Biogeochemistry, 2010, 98: 139−151.
[18]	Zhou W, Han G, Liu M, et al. Effects of soil pH and texture on soil carbon and nitrogen in soil profiles under different land uses in Mun River Basin, Northeast Thailand[J]. PeerJ, 2019, 7: e7880.
[19]	Kemmitt SJ, Wright D, Goulding KW, et al. pH regulation of carbon and nitrogen dynamics in two agricultural soils[J]. Soil Biology and Biochemistry, 2006, 38(5): 898−911.
[20]	魏强,凌雷,柴春山,等. 甘肃兴隆山森林演替过程中的土壤理化性质[J]. 生态学报,2012,32(15):4700−4713.

指标	恢复方式	均值	标准差	最大值	最小值	变异系数/%
pH值	CK	7.06	0.53	5.83	7.99	7.47
	NR	8.09	0.37	6.98	8.57	4.60
	AR	7.58	0.61	6.52	8.39	8.00
有机碳/%	CK	23.55	6.71	11.90	37.35	28.50
	NR	8.73	2.66	4.65	15.00	30.51
	AR	14.70	5.07	10.25	26.86	34.50
总氮/%	CK	1.36	0.36	0.75	1.95	26.42
	NR	0.20	0.14	0.08	0.60	68.89
	AR	0.65	0.35	0.18	1.12	53.61
碳氮比	CK	17.32	2.30	12.16	21.84	13.28
	NR	56.61	26.67	15.57	100.00	47.11
	AR	29.96	17.05	12.27	67.61	56.93
碱解性氮	CK	590.17	156.38	193.40	889.15	26.50
/mg·kg⁻¹	NR	168.89	81.23	43.86	394.81	48.10
	AR	337.58	130.57	87.64	523.00	38.68

	pH值	Soil organic carbon	Total nitrogen	C/N
Soil organic carbon	−0.713***
Total nitrogen	−0.784***	0.916***
C/N	0.701***	−0.526***	−0.727***
Available nitrogen	−0.772***	0.896***	0.958***	−0.688***
***表示相关度达到极显著水平（P<0.001）