____________________________________ Brown, James K.; Smith, Jane Kapler, eds. 2000. Wildland fire in ecosystems: effects of fire on flora. Gen. Tech. Rep. RMRS-GTR-42-vol. 2. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 257 p. This state-of-knowledge review about the effects of fire on flora and fuels can assist land managers with ecosystem and fire management planning and in their efforts to inform others about the ecological role of fire. Chapter topics include fire regime classification, autecological effects of fire, fire regime characteristics and postfire plant community developments in ecosystems throughout the United States and Canada, global climate change, ecological principles of fire regimes, and practical considerations for managing fire in an ecosytem context.

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Wildland fire in ecosystems: effects of fire on flora

In this review, we focus on the biotic parameters that are crucial to an understanding of the recruitment dynamics of North American boreal tree species following natural (fire, budworm infestation, windthrow) or human-induced (clearcut, partial cut) disturbances. The parameters we emphasize are (i) the production of seeds and asexual stems (both of which, we argue, are a function of basal area density), (ii) the dispersal of seeds by wind (or the dispersion of asexual stems) as a function of distance from source, (iii) dormant seed bank capacity, (iv) organic layer depth as a determinant of germinant mortality and asexual bud response, and (v) shade tolerance as a partial arbiter of the density of advanced regeneration. Having identified the gaps in our knowledge, we conclude by suggesting a short-term research agenda whose completion would lead to the parameterized functions that would constitute the recruitment subroutine in a landscape-scale forest dynamics simulator.

https://www.nrs.fs.fed.us/pubs/jrnl/1999/nc_1999_Greene_001.pdf

A review of the regeneration dynamics of North American boreal forest tree species

By analyzing 296 published and unpublished data sets describing annual variation in seed output by 144 species of woody plants, this article addresses the following questions. Do plant species naturally fall into distinct groups corresponding to masting and nonmasting habits? Do plant populations generally exhibit significant bimodality in annual seed output? Are there significant relationships between annual variability in seed production and pollination and seed dispersal modes, as predicted from economy of scale considerations? We failed to identify distinct groups of species with contrasting levels of annual variability in seed output but did find evidence that most polycarpic woody plants seem to adhere to alternating supra-annual schedules consisting of either high or low reproduction years. Seed production was weakly more variable among wind-pollinated taxa than animal-pollinated ones. Plants dispersed by mutualistic frugivores were less variable than those dispersed by either inanimate means or animals that predominantly behave as seed predators. We conclude that there are no objective reasons to perpetuate the concept of mast fruiting in the ecological literature as a shorthand to designate a distinct biological phenomenon. Associations between supra-annual variability in seed output and pollination and seed dispersal methods suggest the existence of important reproductive correlates that demand further investigation.

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Annual variability in seed production by woody plants and the masting concept: reassessment of principles and relationship to pollination and seed dispersal.

Interactions among processes controlling successional change

The pattern of primary succession on the floodplain of the Tanana River in interior Alaska resulted largely from interactions between stochastic events and life history traits of the dom? inant species. Seed rain by willow {Salix alaxensis), alder {Alnus tenuifolia), poplar {Populus balsam- iferd), and spruce {Picea glauca) varied substantially among years but was highest in the successional stage dominated by that species. Some seeds of each species arrived in all stages, and seedlings of all species were initially present in early successional sites. The copious, wind-dispersed seeds and rapid seedling growth rates of willow and poplar resulted in their abundant establishment on early succes? sional vegetated-silt bars. Heavier alder and spruce seeds were less widely distributed, yet rapid growth rates of alder resulted in dense alder thickets within 20 yr of silt bar formation. We found no evidence of buried seed of the four study species. Sown seeds of willow, alder, and poplar established only in early successional vegetated-silt and willow sites. Spruce established in these same sites and in alder sites. Spruce was the only species that naturally colonized mid and late successional sites. Removal ofthe litter and forest floor enabled all species to germinate in all sites. Flooding resulted in substantial mortality of seedlings in early successional sites. A combination of short life span, herbivory by hares, and shade intolerance eliminated willow from mid-successional alder-dominated sites. Thereafter differences in longevity explained successional change from alder to poplar to spruce. Facilitative interactions among species did not appear essential to explain changes in species composition in this primary successional sequence.

R. H. Parkerson

Papers

Case history of an excellent white spruce cone and seed crop in interior Alaska: cone and seed production, germination, and seedling survival.