ARTHROPOD COMMUNITIES IN THE CROWNS OF THE NATURAL AND PLANTED STANDS OF PINUS RADIATA (MONTEREY PINE) IN CALIFORNIA

Abstract

One hundred and ten species of insects together with unidentified spiders and pseudoscorpions were collected in foliage samples of Pinus radiata taken from the three natural mainland populations and two planted populations in California. The diversity of the arthropod community in the crowns of P. radiata D.Don was low with 76% of the total number of individuals accounted for by five species groups and 88% by 11 species groups. Spiders were the most abundant species group, comprising 33% of the total number of individuals. The most abundant insect groups were Homoptera, Hemiptera and Coleoptera, respectively. The natural stands supported more species at higher population levels than the planted stands which supported only two species at very high population levels and the rest at low levels. The arthropod communities at the borders of the natural stands were more diverse than at the centers of the stands. The degree of similarity between the natural stands seemed to reflect their geographic distribution; Ano Nuevo and Monterey were most alike and the differences between Ano Nuevo and Cambria were greater than those between Monterey and Cambria. Differences in insect communities within and between the natural and planted stands are discussed in detail.