Effects of the degree of alpine meadow degradation on the rhizosphere soil fungal community and the ecological network of dominant species

doi:10.11686/cyxb2023106

Abstract

Abstract:

Changes in the diversity and stability of the rhizosphere fungi community can reveal the adaptive mechanisms of microorganisms to degraded ecosystems. The aim of this study was to clarify the influence of changes in dominant species on the diversity and stability of rhizosphere fungal communities. Samples were collected from alpine meadows on the eastern edge of the Qinghai-Tibetan Plateau with four different degrees of degradation （non-degraded grassland， lightly degraded grassland， moderately degraded grassland， and severely degraded grassland）. A combination of ITS rRNA gene sequencing technology， FUNGuild prediction， and molecular ecological network modeling methods was used to analyze the effects of alpine meadow degradation on rhizosphere fungal structure， functional groups， and molecular ecological networks. The results showed that the degree of grassland degradation significantly affected the Beta diversity， but not the Alpha diversity of rhizosphere soil fungi. The degree of degradation only affected the relative abundance of taxa， and had no effect on the dominant fungal communities. The dominant fungal populations in the rhizosphere soils of grasslands with different degrees of degradation were Basidiomycota， Mortierella， and Ascomycota. Linear discriminant analysis Effect Size （LEfSe） identified 29 biomarkers， most of which corresponded to Basidiomycota and Ascomycota. There was a major shift of rhizosphere fungal communities from symbiotic to saprophytic nutrient types with increasing severity of grassland degradation. The network analysis showed that there was a negative correlation between the number of operational taxonomic units （OTUs） of the rhizosphere fungal community and the degree of degradation of the grassland. Combined with data of the network topology parameters， these findings indicate that increasing severity of grassland degradation leads to a looser and more unstable rhizosphere fungal structure. In conclusion， alpine meadow degradation significantly changed the composition， structure， and functional types of rhizosphere fungal communities， especially those of dominant species， and reduced the stability and complexity of fungal communities. These results provide a scientific basis for further research on the adaptive responses of rhizosphere microbe communities to degradation of alpine meadows.

Key words: alpine meadow, meadow degradation, dominant species, rhizosphere soil fungal communities, molecular ecological networks

Yuan MA, Xiao-li WANG, Yu-shou MA, De-gang ZHANG. Effects of the degree of alpine meadow degradation on the rhizosphere soil fungal community and the ecological network of dominant species[J]. Acta Prataculturae Sinica, 2024, 33(2): 125-137.

Figures/Tables 10

References 38

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样地 Plot	海拔 Altitude （m）	纬度 Latitude	经度 Longitude	优势物种 Dominant plant species	盖度 Coverage （%）	高度 Height （cm）	地上生物量 Above-ground biomass （g·m^-2）
未退化草地 ND	3008.3	37°13′05″N	102°44′11″E	珠芽蓼P.viviparum、垂穗披碱草 E.dahuricus、线叶嵩草K.capillifolia	98~100	20.87	403.31
轻度退化草地 LD	2940.0	37°11′58″ N	102°46′17″E	线叶嵩草K.capillifolia、矮生嵩草 K.humilus、扁蓿豆M.ruthenicus	82~85	18.62	364.18
中度退化草地 MD	2869.8	37°11′42″N	102°47′01″E	矮生嵩草K.humilus、线叶嵩草 K.capillifolia、扁蓿豆M.ruthenicus	70~78	17.38	245.42
重度退化草地 SD	2893.6	37°12′05″N	102°45′59″E	乳白香青A.lactea、矮生嵩草K.humilus、垂穗披碱草E.dahuricus	32~38	2.16	99.05

样地 Plot	海拔 Altitude （m）	纬度 Latitude	经度 Longitude	优势物种 Dominant plant species	盖度 Coverage （%）	高度 Height （cm）	地上生物量 Above-ground biomass （g·m^-2）
未退化草地 ND	3008.3	37°13′05″N	102°44′11″E	珠芽蓼P.viviparum、垂穗披碱草 E.dahuricus、线叶嵩草K.capillifolia	98~100	20.87	403.31
轻度退化草地 LD	2940.0	37°11′58″ N	102°46′17″E	线叶嵩草K.capillifolia、矮生嵩草 K.humilus、扁蓿豆M.ruthenicus	82~85	18.62	364.18
中度退化草地 MD	2869.8	37°11′42″N	102°47′01″E	矮生嵩草K.humilus、线叶嵩草 K.capillifolia、扁蓿豆M.ruthenicus	70~78	17.38	245.42
重度退化草地 SD	2893.6	37°12′05″N	102°45′59″E	乳白香青A.lactea、矮生嵩草K.humilus、垂穗披碱草E.dahuricus	32~38	2.16	99.05

样品编号 Sample number	Observed_species指数 OTUs	香农-威纳指数 Shannon-Weiner index	辛普森指数 Simpson index	Chao1指数 Chao1 index	ACE指数 ACE index	覆盖度 Coverage （%）
ND	1121.17±43.70a	6.77±0.20a	0.95±0.01a	1219.75±44.90a	1230.37±44.90a	99.72±0.12a
LD	1147.00±87.50a	6.75±0.63a	0.92±0.02a	1284.89±53.80a	1296.45±52.30a	99.68±0.11a
MD	1068.50±44.20a	6.53±0.18a	0.97±0.01a	1171.07±44.50a	1176.99±43.20a	99.73±0.09a
SD	1063.33±28.10a	6.51±0.17a	0.96±0.01a	1167.33±30.40a	1175.14±30.90a	99.74±0.15a

样品编号 Sample number	Observed_species指数 OTUs	香农-威纳指数 Shannon-Weiner index	辛普森指数 Simpson index	Chao1指数 Chao1 index	ACE指数 ACE index	覆盖度 Coverage （%）
ND	1121.17±43.70a	6.77±0.20a	0.95±0.01a	1219.75±44.90a	1230.37±44.90a	99.72±0.12a
LD	1147.00±87.50a	6.75±0.63a	0.92±0.02a	1284.89±53.80a	1296.45±52.30a	99.68±0.11a
MD	1068.50±44.20a	6.53±0.18a	0.97±0.01a	1171.07±44.50a	1176.99±43.20a	99.73±0.09a
SD	1063.33±28.10a	6.51±0.17a	0.96±0.01a	1167.33±30.40a	1175.14±30.90a	99.74±0.15a

网络 Networks	项目 Item	样地 Plot
网络 Networks	项目 Item	ND	LD	MD	SD
分子生态网络 Molecular ecological networks	总节点Total nodes	839	1219	971	768
	总边Total edges	6901	12929	8445	5985
	幂律系数 R² of power-law	0.712	0.806	0.760	0.728
	负相关边比例 Negative edges percentage （%）	54.31	62.19	69.37	73.92
	连通性Connectedness	0.693	0.859	0.783	0.742
	平均度Average degree	17.39	21.21	16.45	13.63
	平均路径长度Average path length	3.365	3.517	3.844	3.969
	平均聚集系数Average clustering coefficient	0.143	0.146	0.141	0.139
	模块化指数 Modularity	0.366	0.405	0.341	0.329
	介数中心性Centralization of betweenness	0.021	0.036	0.051	0.084
随机网络 Random network	平均路径长度Average path length	2.914±0.012	2.851±0.010	2.929±0.013	3.047±0.015
	平均聚集系数Average clustering coefficient	0.086±0.005	0.088±0.003	0.084±0.004	0.076±0.004
	模块性Modularity	0.176±0.002	0.151±0.002	0.169±0.002	0.197±0.003