Responses of soil microbes across an anthropogenic transition from desert steppe grassland to shrubland in eastern Ningxia

doi:10.11686/cyxb2020195

Abstract

Abstract:

This research investigated the impacts on soil microbes and their enzyme activities， of the anthropogenic transition process from desert steppe to shrubland vegetation. Four site categories： desert grassland （DG）， grassland edge （GE）， shrubland edge （SE） and shrubland （SL） in grassland-shrubland mosaic were selected to represent the transition process， and soil properties， microbial population counts， microbial biomass and enzyme activity in the 0-20 cm soil layer under vegetation patches （VP） and bare interspaces （BI） at each site were measured. It was found that soil moisture， soil organic carbon， total carbon， total nitrogen and total phosphorus decreased from 6.84%， 8.54 g·kg^-1， 22.67 g·kg^-1， 0.85 g·kg^-1， 0.32 g·kg^-1 in DG to 1.78%， 5.85 g·kg^-1， 6.63 g·kg^-1， 0.16 g·kg^-1， 0.23 g·kg^-1 in SL， respectively （P<0.05）， while pH was not significantly changed. Across the transition， bacteria numbers were lowest at GE and SE sites， and slightly lower in SL than DG. Fungi showed a “decrease-rise-decrease” trend， with slightly higher population numbers in SL than in DG. Actinomycete population numbers decreased significantly in SL， compared to DG. The amount of microbial biomass carbon and nitrogen decreased from 87.66 and 5.94 mg·kg^-1 in DG， to 9.94 and 1.85 mg·kg^-1 in SL， respectively （P<0.05）. The activities of catalase， alkaline phosphatase and sucrase showed a significant “decrease-rise-decrease” decline trend in the transition from DG to SL， and urease activity was significantly lower in DG than in SL （P<0.05）. The soil microbe characteristics and enzyme activities were significantly higher under VP than in BI （P<0.05）. Across the vegetation transition， soil moisture， total carbon and total nitrogen were positively correlated with soil microbe-related parameters （actinomycete numbers， soil microbial biomass carbon and nitrogen， and catalase， urease， alkaline phosphatase activities）（P<0.01）， and soil organic carbon and total phosphorus were significantly correlated with soil microbial biomass carbon and urease activity （P<0.05）， while pH was not significantly correlated with soil microbe-related parameters （P>0.05）. Actinomycete numbers， and the enzymatic activities of catalase， alkaline phosphatase and urease were positively correlated with microbial biomass carbon and nitrogen （P<0.01）. However， the numbers of bacteria and fungi and sucrase activities were not significantly correlated with microbial biomass carbon and nitrogen. Across the DG-SL ecological boundary transition （established nearly 30 years）， the indexes observed differed between DG and SL， with SL being significantly lower than DG in most cases， showing that the soil microbial activity of DG is significantly decreased after 30 years as shrubland.

Key words: desert steppe, shrubland, anthropogenic transition, soil microbial quantity, soil microbial biomass, soil microbial enzyme

Ji-xiong GU, Tian-dou GUO, Hong-mei WANG, Xue-ying LI, Dan-ni LIANG, Qing-lian YANG, Jin-yue GAO. Responses of soil microbes across an anthropogenic transition from desert steppe grassland to shrubland in eastern Ningxia[J]. Acta Prataculturae Sinica, 2021, 30(4): 46-57.

Figures/Tables 6

References 48

1	D"Odorico P， Okin G S， Bestelmeyer B T. A synthetic review of feedbacks and drivers of shrub encroachment in arid grasslands. Ecohydrology， 2012， 5（5）： 520-530.
2	Sala O E， Maestre F T， Gibson D. Grass-woodland transitions： Determinants and consequences for ecosystem functioning and provisioning of services. Journal of Ecology， 2014， 102（6）： 1357-1362.
3	Naito A T， Cairns D M. Patterns and processes of global shrub expansion. Progress in Physical Geography， 2011， 35（4）： 423-442.
4	Knapp A K， Briggs J M， Collins S L， et al. Shrub encroachment in North American grasslands： Shifts in growth form dominance rapidly alters control of ecosystem carbon inputs. Global Change Biology， 2008， 14（3）： 615-623.
5	Robinson T P， Klinken R D V， Metternicht G. Spatial and temporal rates and patterns of mesquite （Prosopis species） invasion in Western Australia. Journal of Arid Environments， 2008， 72（3）： 175-188.
6	Eldridge D J， Bowker M A， Maestre F T， et al. Impacts of shrub encroachment on ecosystem structure and functioning： Towards a global synthesis. Ecology Letters， 2011， 14（7）： 709-722.
7	Zhou L H， Shen H H， Chen L Y， et al. Species richness and composition of shrub-encroached grasslands in relation to environmental factors in Northern China. Journal of Plant Ecology， 2017， 12（1）： 56-66.
8	Xie G X， Luo W C， Zhao W Z. The influence of sand source and shrub on the form of shrub sand in desert steppe. Chinese Journal of Deserts， 2015， 35（3）： 573-581.
	谢国勋，罗维成，赵文智. 荒漠草原带沙源及灌丛对灌丛沙堆形态的影响. 中国沙漠， 2015， 35（3）： 573-581.
9	Zhao Y N， Du Y Y， Ma Y P， et al. Soil organic carbon dynamics and prediction of their spatial changes in response to anthropogenically introduced shrub encroachment in desert steppe of Eastern Ningxia， China. Chinese Journal of Applied Ecology， 2019， 30（6）： 1927-1935.
	赵亚楠，杜艳艳，马彦平，等. 宁夏东部荒漠草原灌丛引入过程中土壤有机碳变化及其空间格局预测. 应用生态学报， 2019， 30（6）： 1927-1935.
10	Wei N， Zhao L P， Tan S T， et al. Research progress of grassland shrub. Ecological Science， 2019， 38（6）： 208-216.
	魏楠，赵凌平，谭世图，等. 草地灌丛化研究进展. 生态科学， 2019， 38（6）： 208-216.
11	Gherardi L A， Sala O E. Enhanced precipitation variability decreases grass- and increases shrub-productivity. Proceedings of the National Academy of Sciences， 2015， 112（41）： 201506433.
12	Fuhrman J A. Microbial community structure and its functional implications. Nature， 2009， 459（7244）： 193-199.
13	Chen X， Li W M， Liu Q. Research and analysis of soil microorganism at home and abroad in the past 30 years based on bibliometrics. Acta Pedologica Sinica， 2020， 839（6）： 1-14.
	陈香，李卫民，刘勤. 基于文献计量的近30年国内外土壤微生物研究分析. 土壤学报， 2020， 839（6）： 1-14.
14	Fan Z Z， Wang X， Wang C， et al. Effect of nitrogen and phosphorus addition on soil enzyme activities： A meta-analysis. Journal of Applied Ecology， 2018， 29（4）： 1266-1272.
15	Nicolitch O， Colin Y， Turpault M P， et al. Soil type determines the distribution of nutrient mobilizing bacterial communities in the rhizosphere of beech trees. Soil Biology and Biochemistry， 2016， 103： 429-445.
16	Zheng T T， Chao L， Xie H T， et al. Rhizosphere effects on soil microbial community structure and enzyme activity in a successional subtropical forest. FEMS Microbiology Ecology， 2019， 95（5）： 1-9.
17	Li H， Zhang J， Hu H， et al. Shift in soil microbial communities with shrub encroachment in Inner Mongolia grasslands， China. European Journal of Soil Biology， 2017， 79： 40-47.
18	Wei Y L， Cao W X， Li J H， et al. PLFA analysis of soil microbial community structure in different grazing and enclosed alpine shrub grassland. Journal of Ecology， 2018， 38（13）： 4897-4908.
	韦应莉，曹文侠，李建宏，等. 不同放牧与围封高寒灌丛草地土壤微生物群落结构PLFA分析. 生态学报， 2018， 38（13）： 4897-4908.
19	Bao S D. Analysis of chemical soil （the third edtion）. Beijing： China Agricultural Publishing Press， 2000.
	鲍士旦. 土壤农化分析（第三版）. 北京：中国农业出版社， 2000.
20	Xu G H. Handbook of soil microbial analysis methods. Beijing： Agricultural Publishing Press， 1986.
	许光辉. 土壤微生物分析方法手册. 北京：农业出版社， 1986.
21	Guan S Y. Soil enzyme and its research method. Beijing： Agricultural Publishing Press， 1986.
	关松荫. 土壤酶及其研究法. 北京：农业出版社， 1986.
22	Vance E D， Brookes P C， Jenkinson D S. An extraction method for measuring soil microbial biomass C. Soil Biology & Biochemistry， 1987， 19（6）： 703-707.
23	Gonzalez-Polo M， Austin A T. Spatial heterogeneity provides organic matter refuges for soil microbial activity in the Patagonian steppe， Argentina. Soil Biology and Biochemistry， 2009， 41（6）： 1348-1351.
24	Marusenko Y， Huber D P， Hall S J. Fungi mediate nitrous oxide production but not ammonia oxidation in aridland soils of the southwestern US. Soil Biology and Biochemistry， 2013， 63： 24-36.
25	Ladwig L M， Sinsabaugh R L， Collins S L， et al. Soil enzyme responses to varying rainfall regimes in Chihuahuan Desert soils. Ecosphere， 2015， 6（3）： 1-10.
26	Wainwright J， Parsons A J， Abrahams A D. Plot-scale studies of vegetation， overland flow and erosion interactions： Case studies from Arizona and New Mexico. Hydrological Processes， 2000， 14（16/17）： 2921-2943.
27	Xu Z J， Luo M， Wang W X， et al. Diversity analysis of nitrogen fixing bacteria and nitrogenase gene nifH in 3 typical desert shrubs. Chinese Journal of Deserts， 2014， 34（2）： 472-480.
	徐正金，罗明，王卫霞，等. 3种典型荒漠灌木内生固氮菌及固氮酶基因nifH多样性分析. 中国沙漠， 2014， 34（2）： 472-480.
28	Li M， Yao Q Z， Wei J， et al. Progress in the study of hyphomycetes. Journal of Edible Fungi， 2018， 25（3）： 86-95.
	李敏，姚庆智，魏杰，等. 丝膜菌属真菌研究进展. 食用菌学报， 2018， 25（3）： 86-95.
29	Wang F， Tolgor B A U. Progress in the study of soil fungal diversity. Bacteriological Study， 2014， 12（3）： 178-186.
	王芳，图力古尔. 土壤真菌多样性研究进展. 菌物研究， 2014， 12（3）： 178-186.
30	Bates S T， Garcia-Pichel F. A culture-independent study of free-living fungi in biological soil crusts of the Colorado Plateau： Their diversity and relative contribution to microbial biomass. Environmental Microbiology， 2009， 11（1）： 56-67.
31	Heijden M G A V D， Bardgett R D， Straalen N M V. The unseen majority： Soil microbes as drivers of plant diversity and productivity in terrestrial ecosystems. Ecology Letters， 2008， 11（3）： 296-310.
32	Mueller R C， JayneBelnap， Kuske Cheryl R. Soil bacterial and fungal community responses to nitrogen addition across soil depth and microhabitat in an arid shrubland. Frontiers in Microbiology， 2015， 6： 891.
33	Yan N， Marschner P， Cao W， et al. Influence of salinity and water content on soil microorganisms. International Soil & Water Conservation Research， 2015， 3（4）： 316-323.
34	Wang J S. Effect of litter on microbial community of Songnen grassland under the background of nitrogen deposition. Changchun： Northeast Normal University， 2018.
	王金双. 氮沉降背景下枯落物对松嫩草地微生物群落的作用. 长春：东北师范大学， 2018.
35	Xiang X， Gibbons S M， Li H， et al. Shrub encroachment is associated with changes in soil bacterial community composition in a temperate grassland ecosystem. Plant & Soil， 2018， 425（1）： 1-13.
36	Smith S D， Huxman T E， Zitzer S F. Elevated CO₂ increases productivity and invasive species success in an arid ecosystem. Nature， 2000， 408： 79-82.
37	Turpin-Jelfs T， Michaelides K， Biederman J A， et al. Soil nitrogen response to shrub encroachment in a degrading semi-arid grassland. Biogeosciences， 2019， 16（2）： 369-381.
38	Collins C G， Carey C J， Aronson E L， et al. Direct and indirect effects of native range expansion on soil microbial community structure and function. Journal of Ecology， 2016， 104（5）： 1271-1283.
39	Liao J D， Boutton T W. Soil microbial biomass response to woody plant invasion of grassland. Soil Biology & Biochemistry， 2008， 40（5）： 1207-1216.
40	Pointing S B， Belnap J. Microbial colonization and controls in dryland systems. Nature Reviews Microbiology， 2012， 10（8）： 551-562.
41	Collins S L， Belnap J， Grimm N B， et al. A multiscale， hierachical model of pulse dynamics in arid land ecosystems. Annual Review of Ecology Evolution & Systematics， 2013， 45（1）： 397-419.
42	Li Y L， Chen J， Cui J Y， et al. Nutrient resorption in Caragana microphylla along a chronosequence of plantations： Implications for desertified land restoration in North China. Ecological Engineering， 2013， 53： 299-305.
43	Li X Y， Zhang S Y， Peng H Y， et al. Soil water and temperature dynamics in shrub-encroached grasslands and climatic implications： Results from Inner Mongolia steppe ecosystem of North China. Agricultural & Forest Meteorology， 2013（171/172）： 20-30.
44	Parizek B， Rostagno C M， Sottini R. Soil erosion as affected by shrub encroachment in Northeastern Patagonia. Journal of Range Management， 2002， 55（1）： 43-48.
45	Moorhead D L， Sinsabaugh R L. Simulated patterns of litter decay predict patterns of extracellular enzyme activities. Applied Soil Ecology， 2000， 14（1）： 71-79.
46	Mikutta R， Kleber M， Torn M S， et al. Stabilization of soil organic matter： Association with minerals or chemical recalcitrance. Biogeochemistry， 2006， 77（1）： 25-56.
47	Moorhead D L， Lashermes G， Sinsabaugh R L. A theoretical model of C- and N-acquiring exoenzyme activities， which balances microbial demands during decomposition. Soil Biology and Biochemistry， 2012， 53： 133-141.
48	Vargas R， Collins S L， Thomey M L， et al. Precipitation variability and fire influence the temporal dynamics of soil CO₂ efflux in an arid grassland. Global Change Biology， 2012， 18（4）： 1401-1411.

样地 Sample site	经纬度 Latitude and longitude	pH	容重 Soil bulk (g·cm^-3)	灌木盖度 Shrub coverage (%)	草本盖度 Herbage coverage (%)	物种数 Species number	优势植物 Dominant plant species
荒漠草地 Desert grassland	107°16′24″ E 37°46′31″ N	8.35	1.39	0	70	25	蒙古冰草，短花针茅，猪毛蒿，牛枝子A. mongolicum, S. breviflora, A. scoparia, L. potaninii
草地边缘 Grassland edge	107°16′08″ E 37°46′32″ N	8.19	1.32	6	67	19	牛枝子，远志，乳浆大戟，草木樨状黄芪L. potaninii, Polygala tenuifolia, Euphorbia esula, Astragalus melilotoides
灌丛边缘 Shrubland edge	107°17′43″ E 37°43′59″ N	8.34	1.43	23	48	16	柠条，短花针茅，远志，叉枝鸭葱C. korshinskii, S. breviflora, P. tenuifolia, Scorzoneradivaricata
灌丛地 Shrubland	107°17′52″ E 37°44′55″ N	8.39	1.57	50	13	16	柠条，猪毛蒿，狗尾草，地锦C. korshinskii, A. scoparia, Setaria viridis, Euphorbia humifusa

样地 Sample site	经纬度 Latitude and longitude	pH	容重 Soil bulk (g·cm^-3)	灌木盖度 Shrub coverage (%)	草本盖度 Herbage coverage (%)	物种数 Species number	优势植物 Dominant plant species
荒漠草地 Desert grassland	107°16′24″ E 37°46′31″ N	8.35	1.39	0	70	25	蒙古冰草，短花针茅，猪毛蒿，牛枝子A. mongolicum, S. breviflora, A. scoparia, L. potaninii
草地边缘 Grassland edge	107°16′08″ E 37°46′32″ N	8.19	1.32	6	67	19	牛枝子，远志，乳浆大戟，草木樨状黄芪L. potaninii, Polygala tenuifolia, Euphorbia esula, Astragalus melilotoides
灌丛边缘 Shrubland edge	107°17′43″ E 37°43′59″ N	8.34	1.43	23	48	16	柠条，短花针茅，远志，叉枝鸭葱C. korshinskii, S. breviflora, P. tenuifolia, Scorzoneradivaricata
灌丛地 Shrubland	107°17′52″ E 37°44′55″ N	8.39	1.57	50	13	16	柠条，猪毛蒿，狗尾草，地锦C. korshinskii, A. scoparia, Setaria viridis, Euphorbia humifusa

项目 Item	土壤有机碳 SOC	全碳 TC	全氮 TN	全磷 TP	酸碱度 pH	细菌 Bacteria	真菌 Fungus
土壤水分SM	0.651**	0.911**	0.845**	0.595**	-0.225	0.014	-0.276
土壤有机碳SOC		0.607**	0.538**	0.542**	0.107	-0.156	-0.145
全碳TC			0.794**	0.656**	-0.228	-0.043	-0.272
全氮TN				0.505*	0.022	0.252	-0.008
全磷TP					0.008	-0.018	-0.098
酸碱度pH						0.308	0.338
细菌Bacteria							0.278
项目 Item	放线菌 Actinomycetes	SMB_C	SMB_N	过氧化氢酶 Catalase	脲酶 Urease	蔗糖酶 Sucrase	碱性磷酸酶 Alkaline phosphatase
土壤水分SM	0.511*	0.810**	0.725**	0.581**	0.565**	-0.022	0.686**
土壤有机碳SOC	0.183	0.514*	0.336	0.304	0.453*	-0.028	0.325
全碳TC	0.551**	0.773**	0.722**	0.549**	0.630**	-0.015	0.610**
全氮TN	0.702**	0.956**	0.835**	0.723**	0.795**	0.274	0.842**
全磷TP	0.399	0.483*	0.363	0.375	0.572**	0.006	0.317
酸碱度pH	0.267	0.113	-0.112	0.070	0.073	0.158	-0.062
细菌Bacteria	0.469*	0.330	0.155	-0.007	0.153	0.098	0.247
真菌Fungus	0.172	0.081	0.120	0.348	0.159	0.765**	0.306
放线菌Actinomycetes		0.878**	0.653**	0.765**	0.671**	0.323	0.684**
SMB_C			0.814**	0.846**	0.799**	0.284	0.892**
SMB_N				0.754**	0.666**	0.431*	0.733**
过氧化氢酶Catalase					0.719**	0.439*	0.800**
脲酶Urease						0.275	0.696**

项目 Item	土壤有机碳 SOC	全碳 TC	全氮 TN	全磷 TP	酸碱度 pH	细菌 Bacteria	真菌 Fungus
土壤水分SM	0.651**	0.911**	0.845**	0.595**	-0.225	0.014	-0.276
土壤有机碳SOC		0.607**	0.538**	0.542**	0.107	-0.156	-0.145
全碳TC			0.794**	0.656**	-0.228	-0.043	-0.272
全氮TN				0.505*	0.022	0.252	-0.008
全磷TP					0.008	-0.018	-0.098
酸碱度pH						0.308	0.338
细菌Bacteria							0.278
项目 Item	放线菌 Actinomycetes	SMB_C	SMB_N	过氧化氢酶 Catalase	脲酶 Urease	蔗糖酶 Sucrase	碱性磷酸酶 Alkaline phosphatase
土壤水分SM	0.511*	0.810**	0.725**	0.581**	0.565**	-0.022	0.686**
土壤有机碳SOC	0.183	0.514*	0.336	0.304	0.453*	-0.028	0.325
全碳TC	0.551**	0.773**	0.722**	0.549**	0.630**	-0.015	0.610**
全氮TN	0.702**	0.956**	0.835**	0.723**	0.795**	0.274	0.842**
全磷TP	0.399	0.483*	0.363	0.375	0.572**	0.006	0.317
酸碱度pH	0.267	0.113	-0.112	0.070	0.073	0.158	-0.062
细菌Bacteria	0.469*	0.330	0.155	-0.007	0.153	0.098	0.247
真菌Fungus	0.172	0.081	0.120	0.348	0.159	0.765**	0.306
放线菌Actinomycetes		0.878**	0.653**	0.765**	0.671**	0.323	0.684**
SMB_C			0.814**	0.846**	0.799**	0.284	0.892**
SMB_N				0.754**	0.666**	0.431*	0.733**
过氧化氢酶Catalase					0.719**	0.439*	0.800**
脲酶Urease						0.275	0.696**

[1]	Zhong-chao SUN, Tian-dou GUO, Lu YU, Yan-ping MA, Ya-nan ZHAO, Xue-ying LI, Hong-mei WANG. Changes in soil particle size distribution and fractal characteristics across an anthropogenic transition from desert steppe grassland to shrubland in eastern Ningxia [J]. Acta Prataculturae Sinica, 2021, 30(4): 34-45.
[2]	Zhong-ju MENG, Yan-jie CHEN, Si-qin BAO. Characteristics of community patches under three grazing modes in Sunite Desert-steppe [J]. Acta Prataculturae Sinica, 2021, 30(4): 13-23.
[3]	Mei XIONG, Ji-rong QIAO, Yang YANG, Feng ZHANG, Jia-hua ZHENG, Jian-xin WU, Meng-li ZHAO. Stocking rate effects on stoichiometric characteristics of the steppe grassland pioneer species Stipabreviflora and its underlying soil [J]. Acta Prataculturae Sinica, 2021, 30(2): 212-219.
[4]	Jing-jing ZHANG, Zun-chi LIU, Chuang YAN, Yun-xia WANG, Kai LIU, Xin-rong SHI, Zhi-you YUAN. Effects of soil pH on soil carbon， nitrogen， and phosphorus ecological stoichiometry in three types of steppe [J]. Acta Prataculturae Sinica, 2021, 30(2): 69-81.
[5]	LI Jing, HONG Mei, YAN Jin, ZHANG Yu-chen, LIANG Zhi-wei, YE He, GAO Hai-yan, ZHAO Bayinnamula. The response of vegetation community structure and biomass in Stipa breviflora desert steppe to water and nitrogen [J]. Acta Prataculturae Sinica, 2020, 29(9): 38-48.
[6]	WAN Fang, MENG Zhong-ju, DANG Xiao-hong, WANG Rui-dong, ZHANG Hui-min. C, N and P ecological stoichiometry characteristics of a Stipa species plant-soil system subject to grazing exclusion in a desert steppe [J]. Acta Prataculturae Sinica, 2020, 29(9): 49-55.
[7]	BAO Gen-sheng, SONG Mei-ling, WANG Yu-qin, YIN Ya-li, WANG Hong-sheng. Effects of grazing exclosure and herbicide on soil physical-chemical properties and microbial biomass of Stellera chamaejasme patches in degraded grassland [J]. Acta Prataculturae Sinica, 2020, 29(9): 63-72.
[8]	SUN Shi-xian, DING Yong, LI Xia-zi, WU Xin-hong, YAN Zhi-jian, YIN Qiang, LI Jin-zhuo. Effects of seasonal regulation of grazing intensity on soil erosion in desert steppe grassland [J]. Acta Prataculturae Sinica, 2020, 29(7): 23-29.
[9]	XU Ai-yun, XU Dong-mei, CAO Bing, LIU Jin-long, YU-Shuang, GUO Yan-ju, MA Xiao-jing. Spatial distribution patterns and interspecific relationships of Agropyron mongolicum populations in different desert steppe communities in Ningxia [J]. Acta Prataculturae Sinica, 2020, 29(3): 171-178.
[10]	ZHANG Jian-jun, DANG Yi, ZHAO Gang, WANG Lei, FAN Ting-lu, LI Shang-zhong, LEI Kang-ning. Effect of no-tillage with film and stubble residues on soil nutrients, microbial populations and enzyme activity in dryland maize fields [J]. Acta Prataculturae Sinica, 2020, 29(2): 123-133.
[11]	Zhan-jun WANG, Kun MA, Hui-zhen CUI, Guang-wen LI, Hong-qian YU, Qi JIANG. Correlations between arbuscular mycorrhizal fungi and distribution of main grassland types in Ningxia [J]. Acta Prataculturae Sinica, 2020, 29(12): 150-160.
[12]	Hai-tao CHANG, Ren-tao LIU, Wei CHEN, An-ning ZHANG, Xiao-an ZUO. Distribution of ground-active arthropod community structure after introduction of Caragana korshinskii into Reaumuria soongorica shrubland on the Urat desert steppe， Inner Mongolia [J]. Acta Prataculturae Sinica, 2020, 29(12): 188-197.
[13]	WANG Lei, SONG Nai-ping, CHEN Lin, YANG Xin-guo, WANG Xing. Increase in soil coarse sand content and decrease in soil nutrient levels accompany the transformation of perennial communities to annual communities in desert grassland [J]. Acta Prataculturae Sinica, 2020, 29(11): 183-189.
[14]	HOU Shuai-jun, WANG Ying-xin. Summer grazing of red deer effects on plant diversity of alpine grassland on Qilian Mountain [J]. Acta Prataculturae Sinica, 2020, 29(10): 206-210.
[15]	CHANG Hai-tao, ZHAO Juan, LIU Jia-nan, LIU Ren-tao, LUO Ya-xi, ZHANG Jing. Changes in soil physico-chemical properties and related fractal features during conversion of cropland into agroforestry and grassland: A case study of desertified steppe in Ningxia [J]. Acta Prataculturae Sinica, 2019, 28(7): 14-25.