Ecological Research

, Volume 26, Issue 3, pp 595–603 | Cite as

Effect of Stipa tenacissima L. on the structure of plant co-occurrence networks in a semi-arid community

  • Hugo Saiz
  • Concepción L. Alados
Original Article


Network approaches can increase our understanding of both changes in ecosystems and the role that individual species play in such changes. In ecology, networks have been applied mainly to the study of food webs and mutualistic interactions, with few studies on plant communities. This study used a network approach to examine a semi-arid plant community along a Stipa tenacissima abundance gradient at two locations in SE Spain: (1) an open shrub land where S. tenacissima is a highly competitive species, and (2) an alpha steppe where S. tenacissima forms the end stable successional community. In alpha steppe, the influence of slope was also examined. We detected that S. tenacissima influenced the network structuring process, and that network organization changed along the gradient. In open shrub land, when S. tenacissima became abundant, it dominated the community and other species disappeared. This resulted in a reduction of the number of links that S. tenacissima established. At the alpha-steppe, S. tenacissima coexists with other species, developing more links as it becomes more abundant. On gentle slope zones of alpha steppe, S. tenacissima is more competitive and becomes dominant for high abundance values, reducing its links with other species. The organization of networks varied similarly in both locations. When plant species reduce their abundance and number, links are more heterogeneously distributed in networks. This leads to a concentration of most of the links around a few species, particularly S. tenacissima, which is the most abundant in this case. We conclude that, in order to study plant communities, it is convenient to consider the properties of individual components together with the interaction between them.


Ecological network Spatial network Plants association Stipa tenacissima Semi-arid environment Cabo de Gata-Níjar Natural Park Spain 



The research was made possible by the financial support of CEBCE project Ref. CGL 2008-0065 of the Spanish Ministerio de Ciencia e Innovación. H.S. was supported by a grant JAEPre from the Consejo Superior de Investigaciones Científicas (CSIC). We thank Bruce MacWhirter for critically reading and providing helpful suggestions on the manuscript, and Ángel de Frutos, Yamir Moreno, Yolanda Pueyo and two anonymous referees for their helpful suggestions.

Supplementary material

11284_2011_818_MOESM1_ESM.doc (102 kb)
Supplementary material 1 (DOC 101 kb)


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Copyright information

© The Ecological Society of Japan 2011

Authors and Affiliations

  1. 1.Pyrenean Institute of Ecology (CSIC)ZaragozaSpain

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