Sowing requests for hardwood species have increased in recent years. This is associated with a growing recognition of the value of hardwoods for short rotations, biodiversity, wildlife habitat, riparian area management, their contribution to nutrient cycling, utility for sites difficult to manage for conifers, conifer nurse crops, and their resilience to root rots.
Paper Birch (Ep)
Establishment of planted paper birch seedlings is influenced by a number of limiting factors including brush competition, excessively dry conditions, sunscald, and animal browsing. Because of the difficulties of initial establishment it is desirable to plant stocky seedlings with a vigorous root system and buds along most of the stem. The presence of leaves on the lower stem is important for preventing sunscald damage. Pruning in the nursery is not recommended.
Plate 37 shows birch seedlings in greenhouse production. PSB 515A 1+0 stock type has so far proven to be acceptable to date for both spring and summer plants. The PSB 415D appears to be suitable for summer plant, but is not recommended for spring plant as seedlings become too crowded in the blocks during the longer nursery growing cycle. Smaller container sizes and bareroot stock are not recommended for paper birch.
Detailed information about all aspects of paper birch management is provided in the Paper birch manager's handbook for British Columbia, FRDA Report (1997).
Plate 37. Birch seedlings growing in styroblocks at the Ministry of Forests, Kalamalka Research Station, Vernon. Photo credit: Andrea Eastham.
Black Cottonwood (Ac)
Initial establishment of cottonwood is strongly influenced by brush competition, drought, late spring and early fall frosts, animal browsing, and foliage diseases.
Stock type selection is influenced by the combined consideration of management regime and limiting factors. Unrooted cuttings are a common stock type for intensive poplar farming. Cuttings are typically 40 to 50 cm in length, planted up to 30 cm deep. Genetically superior hybrids play an important role in poplar farming.
For fill planting of poplar farm plantations, or planting on less intensively managed plantations, large unrooted whips from 100 to 250 cm are often used. These larger whips develop leaves above the competing vegetation, but are prone to "planting shock" in the first growing season as the root system establishes.
Unrooted cuttings obtained from managed stool beds tend to be significantly more vigorous than cuttings obtained from wild stock.
Cottonwood can also be established successfully from stock grown in large styroblock containers (515A, 615A) from seed, or from cuttings rooted in the block. Experience gained by the Kalamalka Research Station suggests that the PSB 515A may be the optimal container size for black cottonwood rooted cuttings. PSB 412A or 415D appear optimum for stock types grown from seed (Plate 38).
Plate 38. Black cottonwood PSB 412A 1+0 seedling. Photo credit: Clare Kooistra.
Planting should occur a few weeks before bud burst. Microsite selection should avoid both dry and inundated microsites and ensure full light conditions. Cottonwood is very shade intolerant and will succumb quickly to overtopping vegetation.
Stored cuttings and plug stock are frozen for overwinter storage. One to two weeks prior to planting, storage of whips or cuttings in black plastic bags at 2 to 5°C is recommended to improve moisture content and promote initiation of root primordia.
Detailed information about all aspects of cottonwood management is provided in the Black cottonwood and balsam poplar manager's handbook for British Columbia, FRDA Report 250 (1996).
Red Alder (Dr)
Establishment of red alder is strongly influenced by a number of limiting factors including brush competition, excessively wet or dry conditions, late spring and early fall frosts, sunscald, animal browsing, and insect damage. Because of the difficulties of initial establishment, it is desirable to plant stocky seedlings with a vigorous root system and buds along most of the stem. The presence of leaves on the lower stem is important for preventing sunscald damage.
Considerations of nursery cultivation influence stock type selection. Growing red alder in high density nursery beds leads to etoliation (tall spindly stock), increased watering requirements, which may result in foliage diseases (e.g., botrytis), and reduced branch and bud development on the lower stem.
It is anticipated that preferred stock types will become clear as nursery managers and silviculturists gain more experience with this species. The PSB 412A and PSB 415D may prove to be an acceptable stock type when limiting factors are not severe. For sites with high brush potential or animal browsing pressure, the extra expense of a 512A or 615A may be warranted. However, results to date from planting in B.C. suggest that plug transplant (05+05 PBR 410) stock will provide consistently better survival and early growth than container stock.
Planting precautions for red alder include the following:
Due to the limited experience with red alder plantation establishment in B.C., the current stock types have not been rated with respect to ability to overcome limiting factors.
Detailed information about all aspects of red alder management is provided in the Red alder manager's handbook for British Columbia, FRDA Report 240 (1996).
Trembling Aspen (At)
Small amounts of aspen have been grown in the past few years. Aspen is best propagated from seed since it does not root well from cuttings. Seed should be collected and sown in the same year because it quickly loses viability.
Aspen grows rapidly in the nursery, developing large amounts of foliar mass. PSB 415D is recommended as a container size.