Spatio-temporal aspects of exotic species invasion in an old-field successional system
Kathryn A. Yurkonis
Species distributions through space often change through time as a result of changes in
the local abiotic and biotic environments. However, the processes by which species can
rapidly expand their local distributions are not well characterized. Invasions can occur as
a front through a community or in a guerilla fashion where species spread from multiple
invasion points. This study looks at the distribution and follows invasion of two exotic
invasive species into an old-field successional community. This study follows the
distribution of Lonicera japonica, a woody vine, and Rosa multiflora, a shrub, during a
10-year window in a successional community. Both species reproduce vegetatively and
are considered animal dispersed. Species distributions were analyzed at two scales: in
each of four adjacent 100 x 100m fields that varied in abandonment conditions and across
all four fields. Data analyzed included three collection dates from 1972 to 1982 at fiveyear intervals. This period generally marks the transition from an open to closed canopy
system. Exploratory analyses on the species distributions included geostatistical analyses
and areal data analysis in R. Generally, these two species appear to follow a guerilla
pattern of invasion.