The survival of newly germinated seed depends on its ability to tolerate such factors. First year survival rates are generally low in forest tree species. An established seedling is a seedling that is able to survive and then grow and compete upon its site. Species are typically prolific seed produces with seeds adapted for long-distance dispersal. Germination and growth are rapid allowing the species to quickly occupy the site.
Pioneers are shade-intolerant species.
Species are moderately shade-tolerant and are able to survive in the understory until a gap in the canopy occurs enabling them to occupy the newly formed gap through rapid growth. They are able to gradually reach the overstory as overstory trees die or small gaps are formed. F. Vegetative Reproduction Vegetative reproduction allows pioneer species to quickly re-occupy a disturbed site, taking advantage of established root systems, as well as expand the extent of occupation of a site through clonal development. Vegetative reproduction also allows species to survive under extreme environmental conditions when sexual reproduction is suppressed. Basal sprouts - birch 2.