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Two field experiments were performed to determine if reproductive allocation in 3- to 4-year-old Artemisia tridentata ssp. vaseyana (Rydb.) Beetle, mountain big sagebrush, was affected by spatial dispersion pattern and by small additions of water and/or nitrogen fertilizer In the spatial dispersion study, most measures of reproductive allocation were higher for plants growing singly compared to plants growing in clumps of four shrubs. Total achene biomass and the ratio of total reproductive biomass production/vegetative biomass production (a measure of reproductive effort) for 1984 were much higher for plants growing in a regular pattern In the water and nitrogen fertilizer study, addition of water and fertilizer...
Age and size data on over 2200 trees were used to reconstruct developmental.patterns and regeneration dynamics of four successional and two climax stands of subalpine forests in the Colorado Front Range. The dominant tree species of these forests are Engelmann spruce (Picea engelmannii), subalpine fir (Abies lasiocarpa), limber pine (Pinusflexilis), and lodgepole pine (Pinus contorta). Due to relatively weak relationships between age and size for all four species, patterns of stand development could not have been reliably inferred from size data alone. Following wildfire on the most xeric sites, limber pine is the principal pioneer species and dominates seedling establishment for 50 to 100 or more years. At most...
The seasonality of Glomus fasciculatum associated with Bouteloua gracilis and Pascopyrum smithii was contrasted in the field, as well as the effects of this vesicular-arbuscular mycorrhizal (VAM) fungus on physiological parameters of these grasses in the greenhouse Arbuscule formation was earlier in P smithii, which has C3 photophysiology, than in the C1 B gracilis Soil spore densities were highest in fall samples of both grasses Both grasses exhibited lower stomatal resistance and increased photosynthesis with VAM formation, but these changes were 36% greater for B gracilis B gracilis has a greater percentage of VAM infection than P smithii in the field, but % of the root length infected in the two grasses was...