Small-scale vegetation patterns are frequently the results of plant-plant interactions such as facilitation and competition. Facilitation should be particularly pronounced when both abiotic and biotic stresses are high, but few studies were conducted in such habitats. In heavily-grazed pastures on the eastern Tibetan Plateau, an area with both high abiotic stress and strong biotic disturbance, we made releves of herb species both beneath and outside canopies of three shrub species (Spiraea alpina, Sibiraea angustata and Potentilla fruticosa) differing in palatability and canopy structure. Herb species richness (S). pooled cover (PC) of all species, number of flowering species (FS) and number of inflorescences of all species (IN) were greater outside than beneath the shrub canopies. Evenness (J). in contrast, was smaller outside, while Shannon’s diversity index (H) was the same. Differences in S and J between plots beneath and outside the shrub canopies were greater in the case of P. fruticosa than in the cases of S. angustata and S. alpina. but differences in PC, FS or IN did not depend on the shrub species. Among the common species (frequency ≥6), 47–85% were equally frequent beneath and outside the shrubs, 13–39% were more frequent outside and 3–13% were more frequent beneath the shrubs. For the rarest species (frequency < 6), however, more species occurred beneath than outside the shrubs. The ordination diagram showed a clear separation between the releves outside and beneath the shrubs and a gradient from P. fruticosa via S. alpina to S. angustata. accompanied by a distinct decrease in the extent of the difference between the vegetation beneath and outside the shrub canopies. In conclusion, the three shrub species facilitated some species in the herb layer and each shrub species had a specific impact, related to its canopy structure and palatability but also to the grazing pressure, which was greater around the P. fruticosa shrubs than around S. alpina and S. angustata.
Armas, C. and F.I. Pugnaire. 2005. Plant interactions govern population dynamics in a semi-arid plant community. J. Ecol. 93:978–989.
Arredondo-Núñez, A., E.I. Badano and R.O. Bustamante. 2009. How beneficial are nurse plants? A meta-analysis of the effects of cushion plants on high-Andean plant communities. Community Ecol. 10:1–6.
Bakker, E.S., H. Olff, C. Vandenberghe, K. De Maeyer, R. Smit, J.M. Gleichman and F.W.M. Vera. 2004. Ecological anachronisms in the recruitment of temperate light-demanding tree species in wooded pastures. J. App. Ecol. 41:571–582.
Begon, M., C.R. Townsend and J.L. Harper. 2006. Ecology: from Individuals to Ecosystems, 4th edn. Blackwell, Oxford.
Belsky, A.J. 1994. Influences of trees on savanna productivity: Tests of shade, nutrients, and tree-grass competition. Ecology 75:922– 932.
Bertness, M.D. and R.M. Callaway. 1994. Positive interactions in communities. Trends Ecol. Evol. 9:191–193.
Bossuyt, B., B. de Fré and M. Hoffmann. 2005. Abundance and flowering success patterns in a short-term grazed grassland: early evidence of facilitation. J. Ecol. 93:1104–1114.
Callaway, R.M. 1992. Effect of shrubs on recruitment of Quercus douglasii and Quercus lobata in California. Ecology 73:2118– 2128.
Callaway, R.M. 2007. Positive Interactions and Interdependence in Plant Communities. Springer, Dordrecht.
Callaway, R.M., R.W. Brooker, P. Choler, Z. Kikvidze, C.J. Lortie, R. Michalet, L. Paolini, F.I. Pugnaire, B. Newingham, E.T. Aschehoug, C. Armas, D. Kikodze and B.J. Cook. 2002. Positive interactions among alpine plants increase with stress. Nature 417:844–848.
Callaway, R.M., D. Kikodze, M. Chiboshvili and L. Khetsuriana. 2005. Unpalatable plants protect neighbors from grazing and increase plant community diversity. Ecology 86:1856–1862.
Callaway, R.M. and L.R. Walker. 1997. Competition and facilitation: a synthetic approach to interactions in plant communities. Ecology 78:1958–1965.
Cipriotti, P.A. and M.R. Aguiar. 2005. Interspecific competition interacts with the spatial distribution of a palatable grass to reduce its recruitment. Rangeland Ecol. Manage. 58:393–399.
Facelli, J.M. and A.M. Temby. 2002. Multiple effects of shrubs on annual plant communities in arid lands of South Australia. Austral. Ecol. 27:422–432.
Gómez-Aparicio, L., F. Valladares, R. Zamora and J.L.Quero. 2005. Response of tree seedlings to the abiotic heterogeneity gener-ated by nurse shrubs: an experimental approach at different scales. Ecography 28:757–768.
Kent, M. and P. Coker. 1992. Vegetation Description and Analysis. Belhaven, London.
Klanderud, K. and Ø. Totland. 2004. Habitat dependent nurse effects of the dwarf-shrub Dryas octopetala on alpine and arctic plant community structure. Ecoscience 11:410–420.
Klanderud, K. and Ø. Totland. 2005. The relative importance of neighbours and abiotic environmental conditions for population dynamic parametersof two alpine plant species. J. Ecol. 93:493– 501.
Maestre, F.T., F. Valladares and J.F. Reynolds. 2005. Is the change of plant-plant interactions with abiotic stress predictable? A meta-analysis of field results in arid environments. J. Ecol. 93:748–757.
Meng, H.J., A.H. Pan and Z.Q. Chang. 2003. Analysis of feeding value of several forage shrubs inQilian Mountain. J. Gansu Forest Sci. Tech. 28:11–14.
del Moral, R.1983. Competition as acontrol mechanismin subalpine meadows. Am. J. Bot. 70:232–245.
Oesterheld, M. and M. Oyarzábal. 2004. Grass-to-grass protection from grazing in a semi-arid steppe. Facilitation, competition, and mass effect. Oikos 107:576–582.
Olff, H., F.W.M. Vera, J. Bokdam, E.S. Bakker, J.M. Gleichman, K. de Maeyer and R. Smit. 1999. Shifting mosaics in grazed woodlands driven by the alternation of plant facilitation and competition. Plant Biol. 1:127–137.
Olofsson, J. 2004. Positive and negative plant-plant interactions in two contrasting arctic-alpine plant communities. Arct. Antarct. Alp. Res. 36:464–467.
Rebollo, S., D.G. Milchunas, I. Noy-Meir and P.L.Chapman. 2002. The role of a spiny plant refuge in structuring grazed shortgrass steppe plant communities. Oikos 98:53–64.
Rousset, O. and J. Lepart. 2000. Positive and negative interactions at different life stages of a colonizing species (Quercus humilis). J. Ecol. 88:401–412.
Scheiner, S.M. and J. Gurevitch (eds.) 2001. Design and Analysis of Ecological Experiments, 2nd edn. Oxford University Press, Oxford.
Schütz, M., A.C. Risch, E. Leuzinger, B. Krüsi and G. Achermann. 2003. Impact of herbivory by red deer (Cervus elaphus L.) on patterns and processes in subalpine grasslands in the Swiss National Park. Forest Ecol. Manage. 181:177–188.
Smit, C., M. Gusberti and H. Müller-Schärer. 2006. Safe for saplings; safe for seeds? Forest Ecol. Manage. 237:471–477.
Smit, C., C. Vandenberghe, J. den Ouden and H. Müller-Schärer. 2007. Nurse plants, tree saplings and grazing pressure: changes in facilitation along a biotic environmental gradient. Oecologia 152: 265–273.
Song, M.H., Y.Q Tian, X.L. Xu, Q.W. Hu and H. Ouyang. 2006. Interactions between root and shoot competition among four plant species in an alpine meadow on the Tibetan Plateau. Acta Oecol. 29:214–220.
Tielbörger,K. and R. Kadmon. 2000. Indirect effectsin adesert plant community: is competition among annuals more intense under shrub canopies? Plant Ecol. 150:53–63.
Verdú, M. and P. García-Fayos. 1996. Nucleation processes in a Mediterranean bird-dispersed plant. Funct. Ecol. 10:275–280.
Wang, Q., W.K. Bao, Z.L. Yan, T. Kumpula, A. Colpaert and A. Manderscheid. 2002. Basic types and characteristics ofthe west-ern Zoige Meadows and their changes in recent decades. Chin. J. App. Environ. Biol. 8:133–141.
Wildi, O. and Orlóci, L. 1996. Numerical Exploration of Community Patterns: A Guide to the Use of MULVA-5. 2nd edn. SPB Academic Publishing, Amsterdam.
Wu,N. 1998. The community types and biomass of Sibiraea angus-tata scrub and their relationship with environmental factors in Northwestern Sichuan. Acta Bot. Sin. 40:860–870.
Wu Z. Y. and Chen X. Q. 2004. Flora of China. Science Press, Beijing.
Yan, Y., YY. Zeng, J.H. Zhang, J.G. Zhang and X.H. Zhong. 2005. Diversity of plant species of alpine grassland in Nakchu of Tibet, China. J. Wuhan Univ. 10:659–664.
Yu, F.H., B. Krüsi, M. Schütz, J. Schneller and O.Wildi. 2006. Is vegetation beneath Carex sempervirens tussocks highly specific or an image of the surrounding vegetation? J. Veg. Sci. 17:477– 486.
Zhou, G.J. and H. Li. 2003. Research on the reasons for desertification and countering measures on Zoige Grasslands. J. Sichuan Grassl. 1:35–36.
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Li, P.X., Krüsi, B.O., Li, S.L. et al. Facilitation associated with three contrasting shrub species in heavily grazed pastures on the eastern Tibetan Plateau. COMMUNITY ECOLOGY 12, 1–8 (2011). https://doi.org/10.1556/ComEc.12.2011.1.1
- High-altitude pasture
- Potentilla fruticosa
- Shrub-herb interaction
- Sibiraea angustata
- Spiraea alpina