Data from: Volcanic soils alleviate the allelopathic capacity of Empetrum nigrum in degraded tundra ecosystems

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 Vitrisol) on seed germination and root
elongation of the common grass species Festuca richardsonii in comparison
with Empetrum-associated 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 with 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.