evergreen trees (Clark and Stromberg 1974) . 

 Both were observed in the study area. 



Caches of acorns buried by fox squirrels and 

 left may enhance dispersal. The multi-trunked 

 clustering of oak in the stand may reflect 

 this origin, or else it may reflect a 

 resprouting following disturbance like fire. 



G. POPULATION ECOLOGY 



COMPETITION: All three of the tree species 

 present in the Alzada Oaks stand: Ouercus 

 macrocarpa . Pinus ponderosa . and Juniperus 

 scopulorum require high light conditions 

 for establishment. The first two are climax 

 species at the site and do not develop a 

 closed canopy. The Juniperus scopulorum 

 is not a major community component, but in 

 segments of the population, its establishment 

 is centered around the base of Ouercus 

 macrocarpa . believed to reflect dispersal 

 by avian vectors that prefer the deciduous 

 tree for perch. Few examples were seen in 

 which the former had overgrown the latter. 



HERBIVORY: Leaves of Ouercus macrocarpa 

 are most vulnerable to herbivory after 

 they emerge and their concentration of 

 tannins and phenols are lowest. 



Defoliating insect activity was not noted, 

 but galls were common and leaf-mining 

 occasional. 



Disease warrants mention; heart rot 

 was present in the tree cored along the 

 Little Missouri River, and suspected in 

 the ridge slope trees. 



Tree vigor is low in the harsh Alzada Oak 

 setting, and the majority of trees have 

 dead limbs. However, Ouercus macrocarpa 

 is a rugged tree and almost no standing 

 dead trees are in the area. 



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