Filters: Tags: nitrogen availability (X)
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Past studies of plant?microbe interactions in the alpine nitrogen cycle have revealed a seasonal separation of N use, with plants absorbing N primarily during the summer months and microbes immobilizing N primarily during the autumn months. On the basis of these studies, it has been concluded that competition for N between plants and microbes is minimized along this seasonal gradient. In this study, we examined more deeply the links between microbial population dynamics and plant N availability in an alpine dry meadow. We conducted a year-round ?eld study and per formed experiments on isolated soil microorganisms. Based on previous work in this ecosystem, we hypothesized that microbial biomass would decline before...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Ecology,
Kobresia myosuroides,
N uptake,
alpine tundra,
microbial population dynamics,
The mechanisms responsible for soil-N-mediated species replacement of native perennial grasses by the invasive annual grasses cheatgrass (Bromus tectorum L.) and medusahead (Taeniatherum caput-medusae [L.] Nevski) on rangelands are not completely understood. In addition, the contributions of distinct forms of inorganic N (i.e., NH4+ and NO3-) to these shifts in species composition are currently unclear. Consequently, we conducted a greenhouse experiment to test 2 hypotheses: 1) that low N availability reduces growth (root and shoot) and N allocation of invasive annual seedlings more than native perennial species, and 2) that seedling growth and N allocation of invasive annual grasses is more responsive than native...
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