灌丛化对林草交错带植物和土壤微生物的影响

doi:10.17521/cjpe.2022.0318

摘要/Abstract

摘要：

了解灌丛化对林草交错带内植物和土壤微生物的影响, 有助于提升对林草交错带内灌丛化的认识和管理。该研究在北京东灵山自然保护区的林草交错带内选择不同水平(轻度、中度和重度)的灌丛化样地, 通过样地法和高通量测序技术调查了灌丛化对植物多样性、土壤微生物多样性、植物个体特征和土壤养分的影响, 并进一步揭示了植物多样性、土壤微生物多样性、植物个体特征和土壤养分之间的相关关系, 旨在探究灌丛化对植物和土壤微生物的影响及其机制。结果如下: 1)灌丛化显著降低了植物的多样性, 但乔灌草三者的响应各不相同, 其中草本植物多样性下降最显著; 2)灌丛化显著提升了土壤真菌多样性; 3)灌丛化显著增加了灌木的高度和冠幅, 土壤全氮和有机碳含量随灌丛化水平增加而显著升高; 4)偏最小二乘法路径模型(PLS-PM)发现灌丛化对植物和土壤微生物造成直接影响, 植物个体特征和土壤养分并未对植物和土壤微生物的多样性造成直接影响。冗余分析进一步表明, 灌木高度对植物多样性变化的解释贡献最大, 影响土壤微生物多样性的主要因子为土壤全氮含量。与土壤细菌相比, 土壤真菌的多样性与植物多样性之间更具相关关系。

关键词: 灌丛化, 植物多样性, 土壤微生物多样性, 林草交错带, 东灵山自然保护区

Abstract:

Aims Understanding the effects of shrub encroachment on plant and soil microorganisms in the forest-grassland ecotone will help improve the understanding and management of shrub encroachment in the forest-grassland ecotone.

Methods In this study, different levels (light, moderate and heavy) of shrub encroachment were selected in the forest-grassland ecotone of Dongling Mountain Nature Reserve in Beijing, to explore the effects of shrub encroachment on plant diversity, soil microbial diversity, plant individual trait and soil nutrients by plot method and high-throughput sequencing technology. The correlation between plant diversity, soil microbial diversity, plant individual trait and soil nutrients were also developed in order to further explore the effects of shrub encroachment on plants and soil microorganisms and associated mechanisms.

Important findings Our results showed that: 1) Shrub encroachment significantly reduced the diversity of plants with the different responses of arbor, shrub and herb, among which the diversity index of herb plants decreased in the largest level. 2) Shrub encroachment significantly increased the diversity of soil fungal microorganisms. 3) Shrub encroachment significantly increased the height and crown width of shrubs, while soil total nitrogen and organic carbon contents increased significantly with the increasing shrub encroachment level. 4) The partial least squares path model (PLS-PM) revealed that shrub encroachment had a direct impact on plant and soil microorganisms, whereas plant individual trait and soil nutrients did not have a direct impact on them. The redundancy analysis (RDA) further showed that shrub height made great contribution to the interpretation of changes in plant diversity, and soil total nitrogen content was the main factor in affecting soil microbial diversity. There was a stronger correlation of soil fungal microbial diversity with plant diversity than its relationship with soil bacterial microbial.

Key words: shrub encroachment, plant diversity, soil microbial diversity, forest-grassland ecotone, Dongling Mountain Nature Reserve

张琦, 冯可, 常智慧, 何双辉, 徐维启. 灌丛化对林草交错带植物和土壤微生物的影响. 植物生态学报, 2023, 47(6): 770-781. DOI: 10.17521/cjpe.2022.0318

ZHANG Qi, FENG Ke, CHANG Zhi-Hui, HE Shuang-Hui, XU Wei-Qi. Effects of shrub encroachment on plant and soil microbial in the forest-grassland ecotone. Chinese Journal of Plant Ecology, 2023, 47(6): 770-781. DOI: 10.17521/cjpe.2022.0318

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2022.0318

https://www.plant-ecology.com/CN/Y2023/V47/I6/770

图/表 7

表1 样地信息描述

Table 1 Information of sample plots

灌丛化程度(灌木盖度) Shrub encroachment degree (shrub cover)	草本层优势种 Herb layer dominant species	灌木层优势种 Shrub layer dominant species	乔木层优势种 Arbor layer dominant species
轻度 Light (18%)	披碱草 Elymus dahuricus 山野豌豆 Vicia amoena	沙棘 Hippophae rhamnoides 金露梅 Potentilla fruticosa	白桦 Betula platyphylla 黑桦 Betula dahurica
中度 Moderate (30%)	地榆 Sanguisorba officinalis 披碱草 Elymus dahuricus	沙棘 Hippophae rhamnoides 山刺玫 Rosa davurica	白桦 Betula platyphylla 落叶松 Larix gmelinii
重度 Heavy (48%)	披碱草 Elymus dahuricus 龙牙草 Agrimonia pilosa	沙棘 Hippophae rhamnoides 六道木 Abelia biflora	白桦 Betula platyphylla 落叶松 Larix gmelinii

图1 不同程度灌丛化下植物群落的多样性指数(平均值±标准误)。H, 重度灌丛化; L, 轻度灌丛化; M, 中度灌丛化。不同小写字母表示各样地间差异显著(p < 0.05)。

Fig. 1 Diversity index of plant communities under different degrees of shrub encroachment (mean ± SE). H, heavy shrub encroachment; L, light shrub encroachment; M, moderate shrub encroachment. Different lowercase letters indicate significant differences between plots (p < 0.05).

图2 不同程度灌丛化下微生物群落的多样性指数(平均值±标准误)。A, 真菌多样性指数。B, 细菌多样性指数。H, 重度灌丛化; L, 轻度灌丛化; M, 中度灌丛化。*, p < 0.05。

Fig. 2 Diversity index of soil microbial community under different degrees of shrub encroachment (mean ± SE). A, Fungal diversity index. B, Bacterial diversity index. H, heavy shrub encroachment; L, light shrub encroachment; M, moderate shrub encroachment. *, p < 0.05.

表2 不同程度灌丛化下植物个体特征和土壤养分差异(平均值±标准误)

Table 2 Individual plant characteristics and soil nutrient differences under different degrees of shrub encroachment (mean ± SE)

指标 Index	轻度 Light	中度 Moderate	重度 Heavy
灌木冠幅 Shrub crown width (cm)	108.50 ± 3.75^c	131.55 ± 5.86^b	218.20 ± 2.51^a
灌木高度 Shrub height (cm)	129.66 ± 2.94^c	170.29 ± 8.62^b	215.92 ± 4.88^a
乔木胸径 Arbor diameter at breast height (cm)	23.50 ± 4.64^a	24.22 ± 2.76^a	21.48 ± 1.19^a
乔木高度 Arbor height (cm)	550.43 ± 12.02^a	551.53 ± 16.99^a	560.83 ± 11.57^a
草本高度 Herb height (cm)	43.35 ± 1.22^a	40.60 ± 1.97^b	33.47 ± 2.76^b
土壤全氮含量 Soil total nitrogen content (%)	0.28 ± 0.04^c	0.40 ± 0.02^b	0.57 ± 0.06^a
土壤全磷含量 Soil total phosphorus content (%)	0.07 ± 0.004^a	0.07 ± 0.001^a	0.07 ± 0.006^a
土壤全钾含量 Soil total potassium content (%)	2.17 ± 0.09^a	2.23 ± 0.09^a	2.28 ± 0.11^a
土壤有机碳含量 Soil organic carbon content (%)	3.13 ± 0.33^c	4.79 ± 0.66^b	6.59 ± 0.61^a
土壤pH Soil pH	6.43 ± 0.02^a	6.52 ± 0.08^a	6.56 ± 0.1^a

图3 偏最小二乘法路径模型预测灌丛化对植物(A)和土壤微生物(B)多样性的影响。黑色实线代表显著正相关, 红色实线代表显著负相关, 红(黑)虚线代表无显著相关性, 箭头上数字代表路径系数。

Fig. 3 Partial least squares path models predict the effects of shrub encroachment on plant diversity (A) and soil microbial (B) diversity. The black solid line represents a significant positive correlation, the red solid line represents a significant negative correlation, the dashed line represents no significant correlation, the number on the arrow represents the path factor.

图4 不同灌丛化水平下植物个体特征和土壤养分对植物多样性(A)和微生物多样性(B)的冗余分析(RDA)。A-B, 乔木胸径; A-H, 乔木高度; H-H, 草本株高; S-H, 灌木高度; SOC, 土壤有机碳含量; S-W, 灌木冠幅; TK, 全钾含量; TN, 全氮含量; TP, 全磷含量。H, 重度灌丛化水平; L, 轻度灌丛化水平; M, 中度灌丛化水平; 其后的数字1、2、3代表不同灌丛化水平下的样方编号。B, 细菌; F, 真菌。

Fig. 4 Redundant analysis (RDA) of plant individual characteristics and soil nutrient to plant diversity (A) and microbial diversity (B) at different shrub encroachment levels. A-B, arbor diameter at breast height; A-H, arbor height; H-H, herb height; S-H, shrub height; SOC, soil organic carbon content; S-W, shrub crown width; TK, total potassium content; TN, total nitrogen content; TP, total phosphorus content. H, heavy shrub encroachment level; L, light shrub encroachment level; M, moderate shrub encroachment level; 1, 2, 3 after H, L, M represent sample plot number at different shrub encroachment levels. B, bacterial; F, fungal.

表3 植物多样性与微生物多样性相关性分析

Table 3 Correlation analysis between soil microbial diversity indices and plant diversity indices

微生物多样性指数 Microbial diversity index	植物多样性指数 Plant diversity index
微生物多样性指数 Microbial diversity index	辛普森指数 Simpson index	香农维纳指数 Shannon-Wiener index	Pielou均匀度指数 Pielou evenness index	Margalef丰富度指数 Margalef richness index
真菌香农维纳指数 Fungal Shannon-Wiener index	-0.70^*	-0.74^*	0.40	-0.71^*
真菌辛普森指数 Fungal Simpson index	-0.71^*	-0.74^*	0.42	-0.69^*
真菌Pielou均匀度指数 Fungal Pielou evenness index	0.63	-0.68^*	0.35	0.65
真菌Chao1指数 Fungal Chao1 index	-0.76^*	-0.78^*	0.53	-0.71^*
细菌香农维纳指数 Bacteria Shannon-Wiener index	0.48	0.53	0.01	0.62
细菌辛普森指数 Bacteria Simpson index	0.34	0.38	0.04	0.47
细菌Pielou均匀度指数 Bacteria Pielou evenness index	0.36	0.40	0.04	0.47
细菌Chao1丰富度指数 Bacteria Chao1 index	0.63	-0.70^*	0.07	-0.80^*

参考文献 43

[1]	An QQ, Qiao WY, Li WJ, Chang XF (2021). Effect of shrub encroachment on grassland community structure and above-ground biomass on the Loess Plateau. Acta Botanica Boreali-Occidentalia Sinica, 41, 664-671.
	[安琪琪, 乔文英, 李维军, 常小峰 (2021). 灌丛化对黄土高原草地植物群落结构和地上生物量的影响. 西北植物学报, 41, 664-671.]
[2]	Bardgett RD, Manning P, Morriën E, de Vries FT (2013). Hierarchical responses of plant-soil interactions to climate change: consequences for the global carbon cycle. Journal of Ecology, 101, 334-343. DOI URL
[3]	Chen LY, Li H, Zhang PJ, Zhao X, Zhou LH, Liu TY, Hu HF, Bai YF, Shen HH, Fang JY (2015). Climate and native grassland vegetation as drivers of the community structures of shrub-encroached grasslands in Inner Mongolia, China. Landscape Ecology, 30, 1627-1641. DOI URL
[4]	Claesson MJ, O’Sullivan O, Wang Q, Nikkilä J, Marchesi JR, Smidt H, de Vos WM, Ross RP, O’Toole PW (2009). Comparative analysis of pyrosequencing and a phylogenetic microarray for exploring microbial community structures in the human distal intestine. PLoS ONE, 4, e6669. DOI: 10.1371/journal.pone.0006669. DOI
[5]	Devine AP, McDonald RA, Quaife T, MacLean IMD (2017). Determinants of woody encroachment and cover in African savannas. Oecologia, 183, 939-951. DOI PMID
[6]	Dong K, Ding XF, Hao G, Wang JL, Zhao NX, Gao YB (2021). Effects of enclosure period on population structure of Caragana microphylla and interspecific associations in the Inner Mongolia shrub-encroached grasslands. Acta Ecologica Sinica, 41, 5775-5781.
	[董轲, 丁新峰, 郝广, 王金龙, 赵念席, 高玉葆 (2021). 围封年限对内蒙古灌丛化草原小叶锦鸡儿灌丛结构及群落种间关联的影响. 生态学报, 41, 5775-5781.]
[7]	Eldridge DJ, Bowker MA, Maestre FT, Roger E, Reynolds JF, Whitford WG (2011). Impacts of shrub encroachment on ecosystem structure and functioning: towards a global synthesis. Ecology Letters, 14, 709-722. DOI PMID
[8]	Guan LJ, Mei XF, Zhang YY, Han L, Li QF, Ma CC (2016). Spatiotemporal distribution of soil moisture content and fertility of Caragana stenophylla shrub nabkhas in different habitats. Arid Zone Research, 33, 253-259.
	[关林婧, 梅续芳, 张媛媛, 韩磊, 李清芳, 马成仓 (2016). 狭叶锦鸡儿灌丛沙堆土壤水分和肥力的时空分布. 干旱区研究, 33, 253-259.]
[9]	Hannula SE, Kielak AM, Steinauer K, Huberty M, Jongen R, de Long JR, Long D, Heinen R, Bezemer TM (2019). Time after time: temporal variation in the effects of grass and forb species on soil bacterial and fungal communities. mBio, 10, e02635-19. DOI: 10.1128/mBio.02635-19. DOI
[10]	Horn HS (1974). The ecology of secondary succession. Annual Review of Ecology and Systematics, 5, 25-37. DOI URL
[11]	Hu JF, Xu MS, Tian WB, Zhou WP, Shi QR, Zhou LL, Zhao YT, Zhu DN, Cheng JY, Song YJ, Yan ER (2016). Community structure for main forests in Mount Putuo, Zhejiang Province. Journal of Zhejiang A&F University, 33, 768-777.
	[胡军飞, 许洺山, 田文斌, 周伟平, 史青茹, 周刘丽, 赵延涛, 朱丹妮, 程浚洋, 宋彦君, 阎恩荣 (2016). 浙江普陀山主要林型群落结构特征分析. 浙江农林大学学报, 33, 768-777.]
[12]	Jia GM, Liu BR, Wang G, Zhang BL (2010). The microbial biomass and activity in soil with shrub (Caragana korshinskii K.) plantation in the semi-arid Loess Plateau in China. European Journal of Soil Biology, 46, 6-10. DOI URL
[13]	Jones RT, Robeson MS, Lauber CL, Hamady M, Knight R, Fierer N (2009). A comprehensive survey of soil acidobacterial diversity using pyrosequencing and clone library analyses. The ISME Journal, 3, 442-453. DOI
[14]	Kivlin SN, Hawkes CV (2016). Tree species, spatial heterogeneity, and seasonality drive soil fungal abundance, richness, and composition in neotropical rainforests. Environmental Microbiology, 18, 4662-4673. DOI PMID
[15]	Knapp AK, Briggs JM, Collins SL, Archer SR, Bret-Harte MS, Ewers BE, Peters DP, Young DR, Shaver GR, Pendall E, Cleary MB (2008). Shrub encroachment in North American grasslands: shifts in growth form dominance rapidly alters control of ecosystem carbon inputs. Global Change Biology, 14, 615-623. DOI URL
[16]	Lett MS, Knapp AK (2005). Woody plant encroachment and removal in mesic grassland: production and composition responses of herbaceous vegetation. The American Midland Naturalist, 153, 217-231. DOI URL
[17]	Li F, Pan P, Ning JK, Lai GZ, Ouyang XZ, Xu H, Guo LL, Wu ZR, Yi ZB (2016). Effect of stand spatial structure on understory vegetation diversity of aerial seeding Pinus massoniana plantations. Journal of Northeast Forestry University, 44(11), 31-35.
	[黎芳, 潘萍, 宁金魁, 赖国桢, 欧阳勋志, 徐辉, 郭丽玲, 吴自荣, 易祖滨 (2016). 飞播马尾松林林分空间结构对林下植被多样性的影响. 东北林业大学学报, 44(11), 31-35.]
[18]	Li H, Zhang J, Hu H, Chen LY, Zhu YK, Shen HH, Fang JY (2017). Shift in soil microbial communities with shrub encroachment in Inner Mongolia grasslands, China. European Journal of Soil Biology, 79, 40-47. DOI URL
[19]	Li ZH, Li ZF, Zhang L, Gao XW, Yang HF, Zhang WJ, Wang XJ (2022). Effect of shrub encroachment process on vegetation and soil of desert steppe. Journal of West China Forestry Science, 51(1), 36-41.
	[李梓豪, 李卓凡, 张雷, 高孝威, 杨海峰, 张文军, 王晓江 (2022). 灌丛化过程对荒漠草原植被与土壤的影响. 西部林业科学, 2022, 51(1), 36-41.]
[20]	Ma J, Zhang XJ (2018). Study on arbor-shrub-herb biodiversity of coniferous and broad-leaved mixed forest of Pinus koraiensis. Forest Inventory and Planning, 43(5), 56-59.
	[马菁, 张学俭 (2018). 红松针阔混交林乔灌草生物多样性研究. 林业调查规划, 43(5), 56-59.]
[21]	Mazía N, Moyano J, Perez L, Aguiar S, Garibaldi LA, Schlichter T (2016). The sign and magnitude of tree-grass interaction along a global environmental gradient. Global Ecology and Biogeography, 25, 1510-1519. DOI URL
[22]	Naito AT, Cairns DM (2011). Patterns and processes of global shrub expansion. Progress in Physical Geography, 35, 423-442.
[23]	Pacala SW, Hurtt GC, Baker D, Peylin P, Houghton RA, Birdsey RA, Heath L, Sundquist ET, Stallard RF, Ciais P, Moorcroft P, Caspersen JP, Shevliakova E, Moore E, Kohlmaier G, et al. (2001). Consistent land- and atmosphere-based US carbon sink estimates. Science, 292, 2316-2320.
[24]	Pan XX (2019). The Characteristics of Soil Microbial Structure and Diversity on Nitraria tangutorum Nebkhas of Different Development Stages in Desert Steppe. Master degree dissertation, Ningxia University, Yinchuan.
	[潘笑笑 (2019). 荒漠草原白刺灌丛堆不同演化阶段土壤微生物群落结构及多样性特征研究. 硕士学位论文. 宁夏大学, 银川.]
[25]	Polley HW, Mayeux HS, Johnson HB, Mayeux HS (1994). Atmospheric CO2, soil water, and shrub/grass ratios on rangelands. Ecology, 75, 976-988. DOI URL
[26]	Prober SM, Leff JW, Bates ST, Borer ET, Firn J, Harpole WS, Lind EM, Seabloom EW, Adler PB, Bakker JD, Cleland EE, Decrappeo NM, Delorenze E, Hagenah N, Hautier Y, et al. (2015). Plant diversity predicts beta but not alpha diversity of soil microbes across grasslands worldwide. Ecology Letters, 18, 85-95. DOI PMID
[27]	Qi XX, Zhang SY, Lin F, Zhang LL, Yang DL, Huangfu CH, Wang H (2019). Effect of Flaveria bidentis invasion on plant community and soil microbial community of different invaded soil. Acta Ecologica Sinica, 39, 8472-8482.
	[祁小旭, 张思宇, 林峰, 张玲玲, 杨殿林, 皇甫超河, 王慧 (2019). 黄顶菊对不同入侵地植物群落及土壤微生物群落的影响. 生态学报, 39, 8472-8482.]
[28]	Qin JH, Wang Q, Sun H, Wu YZ, Yi ZX (2012). Review on alpine treeline ecotone and its responses to the global climate change. Journal of Zhejiang Forestry Science and Technology, 32(1), 63-70.
	[秦纪洪, 王琴, 孙辉, 武艳镯, 易之煦 (2012). 高山树线交错带及其对全球气候变化的响应研究进展. 浙江林业科技, 32(1), 63-70.]
[29]	Ratajczak Z, Nippert JB, Collins SL (2012). Woody encroachment decreases diversity across North American grasslands and savannas. Ecology, 93, 697-703. PMID
[30]	Soliveres S, Maestre FT, Eldridge DJ, Delgado-Baquerizo M, Quero JL, Bowker MA, Gallardo A (2014). Plant diversity and ecosystem multifunctionality peak at intermediate levels of woody cover in global drylands. Global Ecology and Biogeography, 23, 1408-1416. PMID
[31]	Trollope WSW, Hobson FO, Danckwerts JE, Van N (1989). Encroachment and control of undesirable plants//Danckwerts JE, Teague WR. Veld Management in the Eastern Cape. Dept of Agriculture and Water Supply, Pretoria, South Africa. 73-89.
[32]	van Auken OW (2009). Causes and consequences of woody plant encroachment into western North American grasslands. Journal of Environmental Management, 90, 2931-2942. DOI PMID
[33]	Wang N, Pan XC, Wang CK, Bai SB (2020). Effects of simulated acid rain on soil fungi diversity in the transition zone of moso bamboo and broadleaf forest. Environment Science, 41, 2476-2484.
	[王楠, 潘小承, 王传宽, 白尚斌 (2020). 模拟酸雨对毛竹阔叶林过渡带土壤真菌结构及其多样性的影响. 环境科学, 41, 2476-2484.]
[34]	Wang SX, Wang XA, Li GQ, Guo H, Zhu ZH (2010). Species diversity and environmental interpretation in the process of community succession in the Ziwu Mountain of Shaanxi Province. Acta Ecologica Sinica, 30, 1638-1647.
	[王世雄, 王孝安, 李国庆, 郭华, 朱志红 (2010). 陕西子午岭植物群落演替过程中物种多样性变化与环境解释. 生态学报, 30, 1638-1647.]
[35]	Wang XD, Liu HQ (2012). Dynamics change of Betula ermanii population related to shrub and grass on treeline of northern slope of Changbai Mountains. Acta Ecologica Sinica, 32, 3077-3086. DOI URL
	[王晓东, 刘惠清 (2012). 长白山北坡林线灌木草本植物与岳桦的动态关系. 生态学报, 32, 3077-3086.]
[36]	Wei N, Zhao LP, Tan ST, Zhao FR (2019). Research progress on shrub encroachment in grasslands. Ecological Science, 38, 208-216.
	[魏楠, 赵凌平, 谭世图, 赵芙蓉 (2019). 草地灌丛化研究进展. 生态科学, 38, 208-216.]
[37]	Yin X, Li DM, Li Y, Wang P, Liu SY, Gao YH (2022). Effects of shrub encroachment on soil hydraulic properties in alpine meadow. Journal of Soil and Water Conservation, 36, 121-129.
	[尹霞, 李冬梅, 李易, 王平, 刘淑英, 高永恒 (2022). 灌丛化对高寒草甸土壤水力性质的影响. 水土保持学报, 36, 121-129.]
[38]	You GY, Liu B, Zou CX, Li HD, McKenzie S, He YQ, Gao JX, Jia X, Arain MA, Wang S, Wang Zhi, Xia X, Xu WG (2021). Sensitivity of vegetation dynamics to climate variability in a forest-steppe transition ecozone, north- eastern Inner Mongolia, China. Ecological Indicators, 120, 106833. DOI: 10.1016/j.ecolind.2020.106833. DOI
[39]	Zhang AL, Zhao JN, Hong J, Yang DL (2018). Characteristics and interaction of soil nematodes and microbial communities in Stipa grandis grassland. Acta Agrestia Sinica, 26(1), 77-84.
	[张爱林, 赵建宁, 洪杰, 杨殿林 (2018). 贝加尔针茅草原土壤线虫与微生物群落特征及其相互作用. 草地学报, 26(1), 77-84.] DOI
[40]	Zhang DXY, Yan YC, Zhang JM, Liu Y, Gao SY, Cai YR, Wang C, Zhu N (2021). Study on plant community characteristics of shrubby grassland in Inner Mongolia. Bulletin of Surveying and Mapping, (S2), 206-209.
	[张戴新月, 闫玉春, 张敬敏, 刘扬, 高思岩, 蔡育蓉, 王储, 珠娜 (2021). 内蒙古灌丛化草原植物群落特征研究. 测绘通报, (S2), 206-209.]
[41]	Zhang X, Wang LL, Liu YH, Wen T, Cui YC, Jiang X, Zhang ZY, Huo D, Li D (2016). Correlation on plant diversity indices and soil physical and chemical indicators of karst natural forest, southern Guizhou Province, China. Acta Ecologica Sinica, 36, 3609-3620.
	[张喜, 王莉莉, 刘延惠, 文弢, 崔迎春, 姜霞, 张佐玉, 霍达, 李丹 (2016). 喀斯特天然林植物多样性指数和土壤理化指标的相关性. 生态学报, 36, 3609-3620.]
[42]	Zhao LP, Liang FH, Wei N, Tan ST, Zhao FR, Li YX (2020). Influences of shrub Caragana brachypoda expansion on vegetation and soil in typical steppe on Loess Plateau. Chinese Journal of Grassland, 42(2), 169-174.
	[赵凌平, 梁方晖, 魏楠, 谭世图, 赵芙蓉, 李元晓 (2020). 短脚锦鸡儿扩张对典型草原植被与土壤的影响. 中国草地学报, 42(2), 169-174.]
[43]	Zhou LH, Shen HH, Chen LY, Li H, Zhang PJ Zhao X, Liu TY, Liu SS, Xing AJ, Hu HF, Fang JY (2019). Species richness and composition of shrub-encroached grasslands in relation to environmental factors in northern China. Journal of Plant Ecology, 12, 56-66. DOI URL