Influence of herbivory and abiotic factors on the distribution of tall forbs along a productivity gradient: a transplantation experiment

In arctic‐alpine areas tall herb vegetation is restricted to sites with high productivity. At higher elevation, low prostate forbs and narrow‐leaved graminoids dominate the vegetation in sites with a protecting snow cover during winter. In this study, I test whether herbivory or abiotic factors prevent tall forbs from growing at higher altitudes. Vegetation blocks from a tall herb meadow were transplanted to herbivore exclosures and open plots in a low‐productive snowbed and a productive tall herb meadow. The tall forbs performed equally well in the exclosures on the low‐productive snowbed as in the tall herb meadow, but decreased in the open plots on the low‐productive snowbed. Thus, even if abiotic factors are ultimately causing many of the vegetation patterns observed in arctic‐alpine plant communities, herbivory appears to be the main proximate factor responsible for the decreasing abundance of tall forbs along gradients of decreasing productivity in arctic‐alpine areas.