Altitudinal variation in ecological strategies across plant communities of different vegetation types

Grime's CSR (competition-stress-ruderality) theory has found widespread use in modern ecology for the analysis of vegetation worldwide. This study aimed to verify if vegetation behavior predicted by this theory coincided with field observations along a highly pronounced altitudinal gradient and to determine if this behavior is the same for different vegetation types. We studied the 275 plots of different vegetation types in the Northern and Subpolar Urals (Russia). Based on the community-weighted mean approach, we allocated the CSR status of each plot. Then, we used generalized additive models and linear modeling to find relationships between CSR statuses, vegetation types and altitude. The plant communities were characterized by a predominance of species with competitor (C) and stress-tolerant (S) strategies and a small share of ruderal (R) species. According to the decrease in the share of competitors and the increase of stress-tolerators, the vegetation types were ranked as follows: forest (C: 47, S: 44), meadow (C: 47, S: 37), bush (C: 44, S: 46), mire (C: 42, S: 49) and mountain tundra (C: 35, S: 58). The different vegetation types showed different responses to elevation changes in the CSR terms. Meadows, bushes and mountain tundra showed the most corresponding behavior with Grime's CSR theory predictions: a significant decrease of the C scores and an increase of S component (4-5% for every 100 m increase in elevation). Finally, forests and mires did not show notable changes in the CSR status.