Small-scale spatial repulsion between the global invader tree Ligustrum lucidum and the native tree Jodina rhombifolia in a temperate neotropical forest
摘要
Invasive trees strongly affect the structure of plant and animal communities and are among the most conspicuous and damaging invasive species. Biotic resistance by native plants against invaders can result in a spatial repulsion. Ligustrum lucidum W.T.Aiton has been widely recognized as a global invasive tree, that massively invades temperate neotropical forests in Argentina. Jodina rhombifolia (Hook. and Arn.) Reissek has been reported as a resistant native tree. We hypothesized that L. lucidum and J. rhombifolia exhibit a negative small-scale spatial relationship but no such spatial pattern is expected between J. rhombifolia and other native trees. In an invaded forest stand we determined the density of different size categories of L. lucidum at increasing distances from stems of J. rhombifolia. The density of other native trees was also estimated. The effect of the distance from J. rhombifolia on the density was estimated by generalized linear models and by simulations.The density of L. lucidum increased about 10 times in a short distance (0–10 m) in all size classes, showing a spatial pattern extremely unlikely under random processes that is independent of competition with native trees. The spatial trend of other native tree density was opposed to that of L. lucidum. The causes of the apparent spatial repulsion between L. lucidum and J. rhombifolia are not known, but chemical interactions could be likely candidates to explain such a pattern. Clumps of J. rhombifolia could help to preserve the structure of native forest at small spatial scale in the invaded forest.