Plant Ecology

, Volume 218, Issue 7, pp 843–854

A dominant dwarf shrub increases diversity of herbaceous plant communities in a Trans-Himalayan rangeland

  • Siddharth Bharath Iyengar
  • Sumanta Bagchi
  • Deepak Barua
  • Charudutt Mishra
  • Mahesh Sankaran


Plant communities are structured by both competition and facilitation. The interplay between the two interactions can vary depending on environmental factors, nature of stress, and plant traits. However, whether positive or negative interactions dominate in regions of high biotic and abiotic stress remains unclear. We studied herbaceous plant communities associated with a dwarf shrub Caragana versicolor in semi-arid, high altitude Trans-Himalayan rangelands of Spiti, India. We surveyed 120 pairs of plots (within and outside shrub canopies) across four watersheds differing in altitude, aspect, and dominant herbivores. Herbaceous communities within shrub canopies had 25% higher species richness, but similar abundance when compared to communities outside the canopy, with the shrub edge having higher diversity than the centre of the canopy. Grasses and erect forbs showed positive associations with the shrub, while prostrate plants occurred at much lower abundance within the canopy. Rare species showed stronger positive associations with Caragana than abundant species. Experimental removal of herbaceous vegetation from within shrub canopies led to 42% increase in flowering in Caragana, indicating a cost to the host shrubs. Our study indicates a robust pattern of a dwarf shrub facilitating local community diversity across this alpine landscape, increasing diversity at the plot level, facilitating rare species, and yet incurring a cost to hosts from the presence of herbaceous plants. Given these large influences of this shrub on the vegetation of these high altitude rangelands, we suggest that the shrub microhabitat be explicitly considered in any analyses of ecosystem health in such rangelands.


Facilitation Alpine Dwarf shrub Altitude Community diversity Grassland Nurse plant 

Supplementary material

11258_2017_734_MOESM1_ESM.pdf (2.4 mb)
Supplementary material 1 (PDF 2423 kb)

Copyright information

© Springer Science+Business Media Dordrecht 2017

Authors and Affiliations

  1. 1.Department of BiologyIndian Institute of Science Education and ResearchPuneIndia
  2. 2.Department of Ecology, Evolution and BehaviorUniversity of MinnesotaSt. PaulUSA
  3. 3.Centre for Ecological SciencesIndian Institute of ScienceBangaloreIndia
  4. 4.Nature Conservation FoundationMysoreIndia
  5. 5.Snow Leopard TrustSeattleUSA
  6. 6.National Centre for Biological SciencesTata Institute of Fundamental ResearchBangaloreIndia
  7. 7.School of BiologyUniversity of LeedsLeedsUK

Personalised recommendations