A high-molecular-weight aspartyl proteinase complex, sensitive to pepstatin A was purified to near electrophoretic homogeneity from dry seeds ofjack pine (Pinus banksiana, Lamb.). Two partial activities, endo-and exo-proteinolytic, were associated with the complex, judged by the analysis of haemoglobin hydrolysis products. The high activity of this enzyme in dry jack pine seed suggests a possible function in early germination.

Two different pre-emergence treatments preventing radicle protrusion by limiting the extent of imbibition were tested on conifer seeds. Osmotic priming in solutions of polyethylene glycol (PEG) which prevented radicle protrusion during prolonged (3 weeks) treatment resulted in variable percentage germination, mean germination time, and coefficient of uniformity of germination among different seedlots when placed on water. All three germination parameters were either unchanged or inferior in seeds subjected to the various PEG concentrations, treatment temperatures and treatment durations when compared with prechilled controls. In contrast, white spruce and jack pine seeds invigorated at 30% moisture content and 15°C in Gore-Tex membrane tubes consistently germinated faster than prechilled control seeds when subsequently placed on water. Tube invigoration affected neither the ability of seeds to complete germination nor the uniformity of germination. The decrease in mean germination time as treatment duration progressed was always linear and plateaued at approximately 4 days after the tube-invigorated seeds were placed on water regardless of species or seedlot. On average, tube invigoration decreased white spruce mean germination time by 0.13±0.02, and black spruce by 0.23±0.03 day per day of invigoration for up to 20 days of treatment. Jack pine mean germination time decreased 0.2±0.04 day per day of invigoration for up to 14 days of treatment.

The threatened Kirtland's warbler Dendroica kirtlandii breeds in stands of young jack pine Pinus banksiana growing on well-drained soils in Michigan, USA. We summarize information documenting the range expansion of Kirtland's warbler due to increased habitat management in the core breeding range in the Lower Peninsula of Michigan during 1990–2000. We collected records and conducted searches for the species in Michigan's Upper Peninsula and Wisconsin over 1978–2000. During that time 25 males were found in Wisconsin and 90 males in the Upper Peninsula. We documented colonization of Michigan's Upper Peninsula by six ringed males from the Lower Peninsula of Michigan. Four ringed birds also moved back to the core breeding range, including two males that made two-way movements between the core breeding range and the Upper Peninsula. Thirty-seven females were observed with males from 1995 to 2000, all in Michigan. Nesting activities were noted for 25 pairs and at least nine nests fledged young. One male ringed as a fledgling returned to breed in two subsequent years. After a 19-year period of population stability, the Kirtland's warbler population increased four-fold during 1990–2000, most likely in response to a tripling in habitat area. This increase in sightings and documented breeding may be related to habitat availability in Michigan's Upper Peninsula and to saturation of habitat in the main breeding range. The increase in extra-limital records during 1995–1999 corresponds to the time when the population went from the minimum to the maximum projected population densities, and a decline in natural wildfire habitat was just offset by new managed habitat for the Kirtland's warbler.