REGENERATION

Cones and Seeds

The high elevation white pines are very slow to mature from a seedling to a cone and seed producing mature tree. The time for these pines to mature from a seedling to a cone - producing tree can be 20 - 50 years; other pines can produce seed in less than 10 years from seedling establishment.

Once a tree reaches maturity it can produce seed for as long as it lives providing the environmental conditions are suitable. The amount and regularity of seed produced varies greatly among species and even among trees of the same species.

The nutritious seeds produced by these pines are an important food source for a variety of wildlife including, bears, squirrels, rodents, birds and others. The Clark 's nutcracker has an important and mutuality beneficial relationship with some of the high elevation pines; the nutcrackers contribute to seed dispersal and benefit from eating the seed. The birds bury the seeds in caches and those that aren't retrieved and eaten sometimes germinate and form tree clusters.

Pollen and seed cone length and color

Species	Pollen Cone Length (mm)	Pollen Cone Color	Seed Cone Length (cm)	Seed Cone Color
Foxtail pine Pinus balfouriana	6 - 10	Red	6 - 9	Purple, aging red - brown
Great Basin bristlecone pine Pinus longeava	7 - 10	Purple - red	6 - 9.5	Purple, aging red - brown
Limber pine Pinus flexilis	15	Pale red or yellow	7 - 15	Straw
Rocky Mountain bristlecone pine Pinus aristata	10	Bluish to red	6 - 11	Purple to brown
Whitebark pine Pinus albicaulis	10 - 15	Scarlet	4 - 8	Dull gray to black purple

Cone Length - 59

Seed length, color, wing length and dispersal

Species	Seed Length (mm)	Seed Color	Seed Wing Length (mm)	Primary Seed Dispersal
Foxtail pine Pinus balfouriana	10	Pale brown, mottled with dark red	10 - 12	Wind
Great Basin bristlecone pine Pinus longeava	5 - 8	Pale brown, mottled with dark red	10 - 12	Wind and Clark 's nutcrackers (suggested but not proven)
Limber pine Pinus flexilis	10 - 15	Brown, at times mottled darker	Nearly wingless	Clark 's nutcrackers, pinyon jays and small mammals
Rocky Mountain bristlecone pine Pinus aristata	5 - 6	Gray brown to near black	10 - 13	Wind and Clark 's nutcrackers
Whitebark pine Pinus albicaulis	7 - 11	Chestnut brown	Wingless	Clark 's nutcrackers

Table sources: Seed length, color and seed wing length - 59 Seed dispersal - 31, 44, 61 - 70

Seedling establishment

Most high elevation white pines reproduce from seed. Vegetative reproduction is infrequent; whitebark pine does occasionally propagate by layering.

The best seedling establishment condition for these pines occurs on disturbed sites. Historically, these pines have thrived in many locations because of their ability to regenerate in openings created by fire and resist many native insects and diseases.

Successful seedling establishment requires the coincidence of seed production and dispersal, suitable ground conditions for germination and favorable weather conditions for seedling growth. The specific requirements for reproduction vary by species and occur infrequently and episodically.

Conditions for seedling establishment and time to maturity

Species	Seedling Establishment conditions	Time to Maturity (seed production) (yrs)
Foxtail pine Pinus balfouriana	Best establishment occurs during warm, wet winters with cool summer temperatures	20 - 50
Great Basin bristlecone pine Pinus longeava	Establishment is a rare, favorable condition to germination and growth is infrequent.	not available
Limber pine Pinus flexilis	Varies	20 - 40
Rocky Mountain bristlecone pine Pinus aristata	Best establishment occurs on open and bare mineral soil after a disturbance like fire.	10 - 40
Whitebark pine Pinus albicaulis	Emergence is best on burned or other exposed mineral soils; Occasional layering may occur especially in krummholz	20 - 30

Table sources: Seed Production - 36, 78, 80, 81, 82 Seedling Establishment - 11, 27, 60, 78, 79, 81

Referred Literature: 85