The role of biotic factors during plant establishment in novel communities assessed with an agent-based simulation model
Authored by Katrin M Meyer, Janina Radny
Date Published: 2018
DOI: 10.7717/peerj.5342
Sponsors:
German Research Foundation (Deutsche Forschungsgemeinschaft, DFG)
Platforms:
NetLogo
Model Documentation:
ODD
Flow charts
Mathematical description
Model Code URLs:
https://www-ncbi-nlm-nih-gov.ezproxy1.lib.asu.edu/pmc/articles/PMC6087422/bin/peerj-06-5342-s003.nlogo
Abstract
Background. Establishment success of non-native species is not only
influenced by environmental conditions, but also by interactions with
local competitors and enemies. The magnitude of these biotic
interactions is mediated by species traits that reflect competitive
strength or defence mechanisms. Our aim was to investigate the
importance of species traits for successful establishment of non-native
species in a native community exhibiting biotic resistance in the form
of competition and herbivory.
Methods. We developed a trait-based, individual-based simulation model
tracking the survival of non-native plants in a native community. In the
model, non-native plants are characterized by high or low values of
competition and defence traits. Model scenarios included variation of
initial number of non-natives, intensity of competitive interaction,
density of herbivores and density as well as mixture of the native
community.
Results. Traits related to competition had a much greater impact on
survival of non-native species than traits related to defence. Survival
rates of strong competitors never fell below 50\% while survival of weak
competitors averaged at about 10\%. Weak competitors were also much more
susceptible to competitive pressures such as community density,
composition and competition intensity. Strong competitors responded
negatively to changes in competition intensity, but hardly to
composition or density of the native community. High initial numbers of
non-native individuals decreased survival rate of strong competitors,
but increased the survival rate of weak competitors. Survival under
herbivore attack was only slightly higher for plants with high defensive
ability than for those with low defensive ability. Surprisingly, though,
herbivory increased survival of species classified as weak competitors.
Discussion. High survival rates of strong non-native competitors relate
to a higher probability of successful establishment than for weak
competitors. However, the reduced survival of strong competitors at high
initial numbers indicates a self-thinning effect, probably mediated by a
strongly competitive milieu. For weak competitors, our model emphasizes
positive effects of high propagule pressure known from field studies.
General effects of herbivory or defence abilities on survival were not
supported by our model. However, the positive effect of herbivory on
survival of weak competitors indicated side effects of herbivory, such
as weakening resident competitors. This might play an important role for
establishment of non-natives in a new community.
Tags
Agent-based model
Competition
Individual-based model
ecology
Climate-change
Trophic interactions
Biotic interactions
Species distribution
Asymmetric competition
Invasive plant
Herbivory
Grassland
Range
shifts
Insect herbivores
Invasion biology
Non-native species
Local
establishment
Range shift
Trait-based model
Enemy release