Daniel D. Uliassi

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Constraints on nitrogen fixation are the ultimate causes of N limitation of primary production, but hypotheses concerning limitations to N2 fixation remain largely untested in natural terrestrial ecosystems. We examined limitations to N2 fixation by thinleaf alder (Alnus tenuifolia) in two stages of primary forest succession on the Tanana River floodplain(More)
If environmental stress provides conditions under which positive relationships between plant species richness and productivity become apparent, then species that seem functionally redundant under constant conditions may add to community functioning under variable conditions. Using naturally co-occurring mosses and liverworts, we constructed bryophyte(More)
Several Alnus species are commonly found growing along rivers and lakes. Alnus forms root nodules with N2-fixing Frankia. We used plant bioassays to detect presence of infective Frankia in river and lake sediments from northern Sweden and Alaska. Silty river water and superficial river and lake sediments from all sites contained infective and effective(More)
In interior Alaskan boreal forests two species of alder, Alnus tenuifolia and Alnus crispa, represent keystone species in floodplain and upland landscapes, respectively, due to the ability of these plants to form symbiotic associations with the nitrogen-fixing actinomycete, Frankia. It is believed that as much as 70% of the nitrogen (N) accumulated during(More)
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