The fertile island effect collapses under extreme overgrazing: evidence from a shrub-encroached grassland

  • Yurong Cai
  • Yuchun YanEmail author
  • Dawei Xu
  • Xingliang Xu
  • Chu Wang
  • Xu Wang
  • Jinqiang Chen
  • Xiaoping Xin
  • David J Eldridge
Regular Article


Background and aims

Woody plant encroachment is a phenomenon of global concern in drylands due to demonstrated reductions in livestock carrying capacity. However, shrubs are known to contribute to the development of patches of enhanced fertility that might offset any negative effects of increasing grazing. We measured soil physical and chemical characteristics within shrub and open patches across a gradient in livestock grazing to explore how the relative effect of shrubs might change with increasing grazing-induced disturbance.


Soil carbon, nitrogen phosphorus and bulk density were measured within 92 shrub patches and their paired interspaces at five sites ranging from long-grazed to long-ungrazed in a semiarid grassland encroached by the N-fixing shrub Caragana microphylla. We used a combination of linear and structural equation modelling to test whether shrubs might buffer any negative effects of overgrazing on soils.


Shrub soils were more porous, and had more organic carbon, nitrogen and phosphorus than interspace soils. Within both microsites, however, soil bulk density increased, and soil organic carbon and nutrients declined, with increasing grazing intensity. Grazing reduced interspace plant cover and height and exacerbated the negative effects of bulk density on soil carbon, whereas shrubs had the opposite effect. The relative importance of shrubs for soil carbon and nutrients increased with increasing grazing intensity but collapsed under extreme overgrazing.


These findings highlight the effect of grazing in promoting shrub dominance, which can also prevent grassland degradation. However, any positive effects of grazing collapsed when sites were severely overgrazed.


Fertile patch Overgrazing Shrub Soil nutrients Temperate grassland 



This study was funded by the National Natural Science Foundation of China (41671044), the National Key Research and Development Program of China (2016YFC0500603), a National Non-profit Institute Research Grant of CAAS (938-1), the International S & T Cooperation Project of China (2017YFE0104500), and the Special Funding for the Modern Agricultural Technology System of the Chinese Ministry of Agriculture.

Author’s contribution

Y. Y. designed the experiment; Y.C., Y.Y., D.X., C.W., and X.W. conducted the field work. Y.C., Y.Y. and D.J.E. performed the data analyses and wrote the manuscript, and all authors provided comments on the manuscript and the revisions and approved the final version.

Supplementary material

11104_2020_4426_MOESM1_ESM.docx (127 kb)
ESM 1 (DOCX 127 kb)


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Copyright information

© Springer Nature Switzerland AG 2020

Authors and Affiliations

  • Yurong Cai
    • 1
  • Yuchun Yan
    • 1
    Email author
  • Dawei Xu
    • 1
  • Xingliang Xu
    • 2
  • Chu Wang
    • 1
  • Xu Wang
    • 1
  • Jinqiang Chen
    • 1
  • Xiaoping Xin
    • 1
  • David J Eldridge
    • 3
  1. 1.Institute of Agricultural Resources and Regional PlanningChinese Academy of Agricultural SciencesBeijingChina
  2. 2.Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources ResearchChinese Academy SciencesBeijingChina
  3. 3.Centre for Ecosystem Science, School of Biological, Earth and Environmental SciencesUniversity of New South WalesSydneyAustralia

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