Lobelia inflata L. is a weedy species that may be abundant in disturbed forest sites. Temperature and light requirements for germination were determined at 12-h daily thermoperiods of 15:6, 20:10, 25:15, 30:15, and 35:20 °C for seeds exhumed after 0–28 months (September 1987 to February 1990) of burial in soil at near-natural temperatures. At maturity in autumn 1987, 2–15% of the seeds germinated after 15 days incubation at the five thermoperiods in light but 0% germinated in darkness. By January 1988, 68–100% of the seeds germinated in light at all thermoperiods except 15:6 °C. Germination at 20:10, 25:15, and 30:15 °C did not decrease to below 60% during the remainder of the study, and germination at 35:20 °C was less than 60% only four times. Germination at 15:6 °C was erratic with peaks in spring 1988, and in spring to early summer and autumn 1989. Regardless of the season in which seeds were exhumed, they did not germinate in darkness. In a laboratory study, stratification at 5 °C broke dormancy but did not substitute for the light requirement. Seeds of L. inflata have the potential to form long-lived seed banks, and buried seeds can germinate at any time during the growing season if exposed to light. Key words: seed dormancy, seed germination, buried seeds, Lobelia inflata, stratification.
The composition and diversity of natural regeneration of tree species in gaps under different intensities of forest disturbance
