Invasive Autumn Olive Species Studied with GIS

header-nac09A STUDY OF ELAEAGANS UMBELLATA DISPERSAL BASED ON THE AGES AND RELATIVE LOCATIONS OF INDIVIDUALS IN A STAND

Mame Redwood, Derek Evans , Chris Evans, David J. Gibson.

Presented at the 36th Natural Areas Conference, “Living on the Edge: Why Natural Areas Matter”, Vancouver, Washington, USA, September 15-18, 2009.

This study examines the spread of the invasive species Elaeagans umbellata (Autumn Olive) based on the ages and relative locations of 76 individuals in a 2.95 hectacre stand. All individuals of E. umbellata in the stand were mapped using GPS in a 20 meter grid with locations subsequently mapped using ESRI ArcGIS. The locations of younger individuals were compared to locations of older individuals to examine dispersal routes and test the null hypotheses that age was homogenous across the stand. The age and diameter of each individual was recorded to allow investigation of the age-to-diameter ratio. Analysis of the ages and diameters showed no consistent age: diameter ratio. Analysis of the relative ages of nearest neighbors indicated a non-random age-class structure (χdf=9 = 56.38, p < 0.0001). Individuals aged 1-4 years most often had 5-9 year old neighbors. Individuals aged 5-9 most often had neighbors of the same age. Individuals aged 10-14 most often had neighbors aged 15+, and individuals aged 15+ most often had neighbors aged 9-14. A map presenting the ages and relative locations of individuals showed a cluster of older individuals which appear to be the founder plants during colonization of the stand.