REDUCED MYCORRHIZAE ON JUNIPERUS-MONOSPERMA WITH MISTLETOE - THE INFLUENCE OF ENVIRONMENTAL-STRESS AND TREE GENDER ON A PLANT PARASITE AND A PLANT-FUNGAL MUTUALISM

被引:75
|
作者
GEHRING, CA
WHITHAM, TG
机构
[1] Department of Biological Sciences, Northern Arizona University, Flagstaff, 86011, AZ
关键词
DIOECY; ENVIRONMENTAL STRESS; PARASITIC MISTLETOE; MUTUALIST; MYCORRHIZAL FUNGI;
D O I
10.1007/BF00317231
中图分类号
Q14 [生态学(生物生态学)];
学科分类号
071012 ; 0713 ;
摘要
We examined how an important plant mutualist (fungal mycorrhizae) interacted with a common tree parasite, a xylem-tapping mistletoe (Phoradendron juniperinum Engelm.) growing on one-seeded juniper (Juniperus monosperma Engelm.). We also examined how host tree gender and environmental stress might be involved in this interaction. Four major patterns were observed. First, the mycorrhizal levels of trees of both sexes were negatively correlated with mistletoe density. In comparisons of heavily and lightly infested trees at the stressful site, high mistletoe levels were associated with 27% less mycorrhizae on male trees and 38% less mycorrhizae on the roots of female trees. Second, the reduction of mycorrhizae on trees with high mistletoe levels was slightly but significantly greater for female trees than male trees. These results are consistent with the hypothesis that severe mistletoe infestation suppresses mycorrhizae and that this suppression is more severe in female trees because of their greater energetic investment in reproduction. Third, female junipers growing in the stressful ash and cinder fields averaged three-fold higher levels of mistletoe infestation than male trees. Fourth, no differences in mistletoe infestation were observed between male and female trees growing in the more favorable soils. Comparisons with other systems suggest that both mistletoes and herbivores have similar interactions with mycorrhizae.
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页码:298 / 303
页数:6
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