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We found the hybrid zone between Eucalyptus amygdalina and Eucalyptus risdonii to be a center of insect and fungal species richness and abundance. Of 40 taxa examined, 73% were significantly more abundant in the hybrid zone than in pure zones, 25% showed on significant differences, and 2% were most abundant on a pure host species. The average hybrid tree(More)
The goldenrod leaf beetle, Trirhabda canadensis, is known to respond to odors of host and non-host species in the laboratory. Here we report movements of T. canadensis in the field in response to volatile odors from monocultures and polycultures of host plants. Overall, beetles preferentially colonized plots with a higher density of host plants and lower(More)
Levels of insect attack and yields of leaf essential oils in Eucalyptus vary widely within and among species. We tested the hypotheses that 1) metabolic cost of oil detoxification increases with increasing oil yield, resulting in lower herbivore growth rates and, consequently, 2) in lower herbivore damage to plants. Distribution of insect damage, eggs,(More)
The photosynthetic response of Heteromeles arbutifolia, a California evergreen shrub, was measured in natural habitats representing both the climatic center of distribution and the southern warm arid extreme of this species. At all sites the seasonal carbon gain was limited primarily by available water, secondarily by photoperiod, and only slightly by(More)
Sawfly larvae of the subfamily Perginae have a diverticular pouch of the foregut in which they store an oily fluid that they regurgitate when attacked. The fluid, which is an effective deterrent to ants, birds, and mice, is essentially identical chromatographically to the oils of the Eucalyptus leaves on which the larvae feed. The significance of the(More)
Many long-lived plants are known to prolong dormancy in response to abiotic stresses such as drought. We are unaware, however, of any reports of plants prolonging dormancy in response to biotic stresses such as herbivory. We monitored 140 putative Solidago missouriensis clones (hereafter ÔclonesÕ) ‡ 13 years before, during and after intense defoliation by(More)
A field study was initiated to determine the patterns of water stress imposition and stomatal resistance to gas exchange in representative species of 2 evergreen sclerophyllous communities. In concurrent experiments plant water potential, temperature and vapor pressure gradient were varied to determine the relative importance of morphological and(More)