Volcanic soils alleviate the allelopathic capacity of Empetrum nigrum in
degraded tundra ecosystems
Abstract
Land degradation due to unsustainable land use is of major concern
worldwide and recovery is often slow. A potential mechanism behind slow
recovery of degraded ecosystems is the retarding impacts of allelopathic
plant species on the establishment of species that might facilitate the
recovery process. However, the strength of the retarding impact may
depend on soil type. In this study, we investigated the potential role
of an abundant, evergreen and allelopathic dwarf shrub, Empetrum nigrum,
in trapping tundra ecosystems in a degraded state in Iceland after
centuries of unsustainable land use. We first run a series of bioassays
to assess the potential allelopathic legacy effects of the
Empetrum-associated volcanic soils (Andosol and Vitrosol) on seed
germination and root elongation of the common grass species Festuca
richardsonii in comparison with non-volcanic Histosol and Podzol soil
types. Then we assessed the Empetrum leaf-soil interactions for all soil
types using leaves from a degraded site in Iceland. We found no
potential allelopathic legacy effects of Empetrum associated volcanic
soils, whereas the non-volcanic soils negatively impacted Festuca root
elongation. Empetrum leaves alone affected both seed germination and
root elongation. These effects were strongly alleviated by the volcanic
soils, but not by the non-volcanic soils. We conclude that abundant
allelopathic plant species may significantly contribute to trapping
tundra ecosystems in a degraded state, but the strength of this trapping
mechanism depends on the soil environment .