Mechanisms of Primary Succession Following Deglaciation at Glacier Bay, Alaska

• Published in: Ecological Monographs
• Main Authors: Chapin, F. Stuart, Walker, Lawrence R., Fastie, Christopher L., Sharman, Lewis C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1994
• Subjects: Glacier Bay; glacier; Alaska
• Online Access: http://dx.doi.org/10.2307/2937039; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2307%2F2937039; https://onlinelibrary.wiley.com/doi/pdf/10.2307/2937039; https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.2307/2937039

In primary succession following deglaciation at Glacier Bay, Alaska, we tested the hypothesis that the major effect of initial nitrogen—fixing colonizers is to facilitate establishment of late—successional dominants and that other possible causes of successional change (e.g., life history factors governing seed rain and competitive interactions among species) need not be invoked. Environment changed dramatically through the first 200 yr of succession. Soil organic matter increased 10—fold in the upper mineral soil with corresponding increases in soil moisture, total nitrogen (N), and capacity to support plant growth and declines in bulk density, pH, and total phosphorus (P). Plant growth in pioneer soils tended to be simultaneously limited by both N and P, as well as by unknown factors (perhaps lack of mycorrhizae), whereas only P limited growth in older soils. Light availability to seedlings declined through succession. Early—successional species (Epilobium latifolium, Dryas drummondii) had smaller seeds, younger age at first reproduction, shorter life—span, and shorter height at maturity than did mid—successional (alder, Alnus sinuata) and late—successional species (sitka spruce, Picea sitchensis). Seed rain of alder and spruce was negligible in the pioneer stage, increased prior to the stage in which a species was dominant, and was greatest in the stage in which a species dominated. Vegetation in each successional stage inhibited germination and initial establishment of sown alder and spruce seeds (except a tendency of the "black—crust") algal/microbial community in the pioneer stage to enhance survivorship). Removal of the surface litter layer generally enhanced germination and survivorship, particularly of alder. Comparisons of germination in the greenhouse and the field indicated that climatic or indirect vegetation effects (e.g., differential seed predation) and allelopathy also reduced germination and establishment in vegetated communities. Naturally occurring spruce seedlings grew most rapidly in the ...