Emergence of a mid-season period of low floral resources in a montane meadow ecosystem associated with climate change
Article first published online: 16 MAR 2011
© 2011 The Authors. Journal of Ecology © 2011 British Ecological Society
Journal of Ecology
Volume 99, Issue 4, pages 905–913, July 2011
How to Cite
Aldridge, G., Inouye, D. W., Forrest, J. R. K., Barr, W. A. and Miller-Rushing, A. J. (2011), Emergence of a mid-season period of low floral resources in a montane meadow ecosystem associated with climate change. Journal of Ecology, 99: 905–913. doi: 10.1111/j.1365-2745.2011.01826.x
- Issue published online: 14 JUN 2011
- Article first published online: 16 MAR 2011
- Received 27 August 2010; accepted 11 February 2011 Handling Editor: Jonathan Newman
- climate change;
- cumulative flowering density;
- flower abundance;
- flowering phenology;
- plant–climate interactions;
- resource availability;
- Rocky Mountain Biological Laboratory
1. Shifts in the spatial and temporal patterns of flowering could affect the resources available to pollinators, and such shifts might become more common as climate change progresses.
2. As mid-summer temperatures have warmed, we found that a montane meadow ecosystem in the southern Rocky Mountains of the United States exhibits a trend toward a bimodal distribution of flower abundance, characterized by a mid-season reduction in total flower number, instead of a broad, unimodal flowering peak lasting most of the summer season.
3. We examined the shapes of community-level flowering curves in this system and found that the typical unimodal peak results from a pattern of complementary peaks in flowering among three distinct meadow types (dry, mesic and wet) within the larger ecosystem. However, high mid-summer temperatures were associated with divergent shifts in the flowering curves of these individual meadow types. Specifically, warmer summers appeared to cause increasing bimodality in mesic habitats, and a longer interval between early and late flowering peaks in wet and dry habitats.
4. Together, these habitat-specific shifts produced a longer mid-season valley in floral abundance across the larger ecosystem in warmer years. Because of these warming-induced changes in flowering patterns, and the significant increase in summer temperatures in our study area, there has been a trend toward non-normality of flowering curves over the period 1974–2009. This trend reflects increasing bimodality in total community-wide flowering.
5. The resulting longer periods of low flowering abundance in the middle of the summer season could negatively affect pollinators that are active throughout the season, and shifts in flowering peaks within habitats might create mismatches between floral resources and demand by pollinators with limited foraging ranges.
6. Synthesis. Early-season climate conditions are getting warmer and drier in the high altitudes of the southern Rocky Mountains. We present evidence that this climate change is disrupting flowering phenology within and among different moisture habitats in a sub-alpine meadow ecosystem, causing a mid-season decline in floral resources that might negatively affect mutualists, especially pollinators. Our findings suggest that climate change can have complex effects on phenology at small spatial scales, depending on patch-level habitat differences.