Data from: Functional traits associated with the establishment of introduced Phytophthora spp. in Swedish forests

1. Invasive forest pathogens of the genus Phytophthora are threatening
ecosystems globally. Phytophthora species are mainly introduced by humans
importing infected nursery stock. However, due to the presence of
environmental filters, not all introduced Phytophthoras manage to
establish and spread. Some Phytophthoras’ ability to overcome these
filters may be linked to functional traits. In Northern Europe, the
increasing number of reports calls for a better understanding of the
invasion process to prevent future outbreaks. 2. We hypothesized that the
incidence of invasive Phytophthoras in urban locations would be higher
than in remote forests, that there would be a decrease of species richness
along the invasion process because of environmental filtering, and that
there would be a functional shift among Phytophthora communities between
stages of invasion. We compared the species composition of 96 plots from
16 rivers running through areas that constitute a gradient of human
influence. We also compared the species composition and functional
diversity of Phytophthora communities in 8 nurseries and 14 forests,
including anthropogenic and natural forests. Phytophthoras were isolated
from river water, soil, and/or plant tissue. Cultures were identified
based on the Internal Transcribed Spacer (ITS) region. 3. Three
Phytophthoras were detected in all environments (P. cactorum, P.
plurivora, and P. cambivora). Their incidence was higher in urban
locations than in remote forests, supporting the role of human activity as
a driver of invasion. Most of the Phytophthoras detected in forests were
detected in nurseries. The Phytophthora community in nurseries was richer
and more diverse than in forests, pointing to environmental filtering
affecting the establishment. Phytophthora communities in nurseries and
forests differed in their functional divergence. Traits associated with
establishment were the ability to form asexual survival structures and
lower cardinal temperatures for growth. 4. Synthesis and applications. Our
findings support the view that human activities act as drivers of
Phytophthora invasions, and suggest that Phytophthoras that are able to
form asexual structures are more likely to establish in northern Europe.
The results increase the capacity to predict the establishment of
Phytophthora species in Sweden and expand our understanding of the
invasion process of forest pathogens.15-Nov-2017