Factors Controlling Species Richness in Alpine Plant Communities: An Assessment of the Importance of Stress and Disturbance

• Published in: Arctic, antarctic, and alpine research antarctic, and alpine research, 2002-11, Vol.34 (4), p.398-407
• Main Authors: Kammer, Peter M., Möhl, Adrian
• Format: Article
• Language: English
• Subjects: Acid soils; Alpine grasslands; Alpine plants; Communities; Grassland soils; Humus; Plants; Species; Talus slopes; Vegetation
• ISSN: 1523-0430; 1938-4246
• DOI: 10.1080/15230430.2002.12003510

This study explores whether the high variability of vascular plant diversity among alpine plant communities can be explained by stress and/or disturbance intensities. Species numbers of 14 alpine plant communities were sampled in the Swiss Alps. To quantify the intensity of 13 stress and 6 disturbance factors potentially controlling plant life in these communities, a survey was conducted by asking numerous specialists in alpine vegetation to assess the importance of the different factors for each community. The estimated values were combined in stress- and disturbance-indices which were compared with diversity according to the Intermediate Stress Hypothesis, the Intermediate Disturbance Hypothesis, and the Dynamic Equilibrium Model, respectively. Each of these theories explained a part of the variability in the species richness, but only the Dynamic Equilibrium Model provided a complete and consistent explanation. The last model suggests that community species richness within the alpine life zone is generally controlled by stress intensity. Disturbance and competition seem to play a secondary role by fine-tuning diversity in specific communities. As diversity is primarily limited by stress, a moderation of temperature-related stress factors, as a result of global warming, may cause a shift of the equilibrium between stress, disturbance, and competition in alpine ecosystems.