Regeneration Mechanisms
Mechanisms of Regeneration
• Some species are capable of more than one
• Sexual
• Vegetative
Seed• All species have to have this
capability• May be uncommon• Small seed• Large seed• When dissemination?• How disseminated?
Stump Sprouts• Well established root system• Large store of carbohydrates• Young and vigorous stronger than old• Most angiosperms
– bigleaf maple– red alder
Root Suckers
• Can use root system for short period• Stored carbohydrates• Often soil temperature dependent• Some angiosperms
– aspen
Layering
• Pieces of stem form adventitious roots and shoots
• Some angiosperms and some conifers– vine maple– black and balsam popular– red cedar
USDA Forest Service
Underground stems
• Non-trees– Ferns
hay-scented fern (Dennstaedtia punctilobula )
Steve Horsley, USDA Forest Service, Bugwood.org
Buried Seed• Some seed stays alive in the duff for
many years (or decades)
– cherry– Rubus (salmonberry)
Advance Regeneration• Some species can remain alive in the
understory for long periods• May periodically die back to the root
collar• Must be quite shade tolerant• Angiosperms and conifers
– true firs– hemlock?– red cedar?– salal
1915
1930
Relationship With Disturbances
• Competitive ability is directly impacted by disturbance
• This information can be used in silvicultural planning
Intensity
• Less intense favors sprouting and advance regeneration
• Mid intensity favors layering, underground stems and perhaps buried seed
• Most intense favors seeding
Frequency
• Long intervals favor advance regeneration and sometimes seed
• Short intervals favor sprouting
Scale
• Seed may not be able to travel full distance of large scale disturbances
– “generation and a half”
Examples• Wind – advance regeneration, perhaps
seed on windthrow mounds• Cool fire – sprouting• Hot fire – root suckering, seed, buried
seed• Avalanches – advance regeneration,
sprouting
Examples• Light cutting – advance regeneration
• Heavy cutting – sprouting, seed of all types
• Machinery has effect
Site Prep
• Changes disturbance regime