Patrick N. McGovern 2022
Current Poplar and Willow culture focuses on clones that root well but don't re-generate from root suckers. Aspen trees have a natural tendency to grow new shoots from their root systems when the main stem has been removed or killed by fire. This capability allows an aspen clone to survive for generations and perhaps thousands of years.
We propose using aspens with some P. alba parentage and the capability to root from dormant cuttings. Options include planting large 1-0 8' rooted or unrooted poles, smaller 18" rooted stock or 14" dormant cuttings. Planting aspens at wider spacings then removing them after about 5-7 years or inter-planting with another compatible species (e.g. Larch) could later convert the site to aspens and not require replanting.
Below are proposed strategies that require additional testing of this approach:
STRATEGY 1: Three Stage Aspens - 40 Trees per acre with rooted or un-rooted stock grown from coppiced stools:
Stage 1: Establish Coppice Stool Beds: Cultured stump sprouts or "Coppiced stools" should produce 8'-10' pole stock (whips) and be harvested annually for re-planting. Plant stool beds using good rooting aspen clones in 2' x 6' rows in a fertile, irrigated and fenced in area. If fencing is not possible, consider coppicing the whips at 4' to 5' height and protect the lower stem as needed (see this 2 year old coppiced tall stool). Aspens will spread sucker shoots over time so you may need to have separate stool beds for each clone. Each stool should yield 5-7, 4' to 10' poles so plant enough stools for your planting needs. Harvest the poles in February when convenient. Bound them and bag the bottoms, store in cooler. It should also be possible to harvest stock in the early Spring before the buds flush for immediate planting. Healthy stools should produce abundant whips for 6+ years with higher quality cuttings and better rooting performance.
Another option may be to simply harvest a portion of the one year whips the year following the first harvest of the 5-7 year trees. This option may work best if the site is fertile, had sufficient water and not over browsed by deer/rodents.
Stage 2: Plant 18" Rooted Ministools, Unrooted dormant cuttings or 7' rooted stock:
18" "MiniStools" (MS) are 1-0 rooted stock, nursery grown from 8" cuttings with a 6" stem and roots pruned to 1" stubs with a 3.5” maximum root ball width, then stored in 3 gallon zip bags in a refrigerator at 30 F degrees. Ministools have exisiting roots providing higher survival, more vigorous growth and can be propagated with stems from the previous year's mini-stools, negating the need for expensive stool beds. See Mini-stool stock photo.
14" Dormant cuttings: are 14" long and at least 3/8" in diameter at the top end are also valid planting options. Be sure to use clones with proven ability to root well from dormant stem cuttings.
Plant Sometime in April/May depending upon local conditions and previous tests. You can plant some time after the frost leaves the ground to avoid storing stock in a cooler.
Soak the planting stock in water for about 24 hours before planting. If overnight is not possible then soaking for an hour or two is still worthwhile.
Plant 36 (35' apart) to 100 (21' apart) trees per acre. Document and plant at least 5 different clones in separate areas/rows to give them their own space and make it easier to identify their planting areas when they sucker.
Other planting options include planting 150 aspens to the acre, spaced 17' apart with alternate rows planted to Larch, then harvest the entire site at age 20 to 30 with the regenerated site converting to aspen.
Use a planting spade to open a 10" deep slice and insert the ministool or cutting tree then open another slit before the cutting and push the earth firmly towards the tree. The planted 18" stock should have a 4" stem above ground.
Protect the stems from damage: Note that the 5 foot tree shelters have worked well, but may harbor insects and promote a tall but slender stem. Also, consider using 1.5' or 3' stapled woven textile fabric (aka "sleeves") supported by 2 bamboo stakes. We prefer the 1.5' sleeves since they prevent deer over browsing the stems and may produce a branchy stem may be less desirable for deer rubbing. You may want to
How to produce and use white fabric tree sleeves:
1) 3' Woven textile fabric secured to 6' - 7' 1-0 rooted tree stock:
Purchase woven textile white fabric rolls in 3' lengths and secure with stainless steel office size staples to avoid toxic rust damage caused by standard steel staples when securing the sleeve to the stem.
Cut a - 3' x 12" white ground cover fabric strip. Fold lengthwise and staple the sides at right angles to the edge. Keep the lower 6"" staples tight and other staples 4" apart for ventilation. Consider pre-fabricating the sleeves off site and place over the planted stem whip on-site.
Place the sleeve over the whip with the stapled edge facing South allowing sprouts to grow if the stem is injured. Starting at the bottom, put 4 stainless steel staples on each side.
2) 1.5' or 3' White fabric tree sleeve secured to 2 4' bamboo stakes for 18" ministools or dormant cuttings:
Materials:
Estimated per unit material cost in 2021: 1.5' shelter ~ $.5 each
White fabric with 4' bamboo stake sleeve process:
Cut Fabric Sleeves: Cut a - 3' x 12" white fabric strip. Fold lengthwise and apply 3 staples at right angles to the edge. Space staples 1" apart for the bottom 8" then place sets of 3 close staples every 4" and at the top. This secures the bottom 8" for herbicide/rodent protection while the upper 4" staple sets allow for ventilation.
This can also be adapted to a half sized 1.5' tall fabric tree tube length, but using the same 4' stakes.
Staple 2 - 4' stakes to the inside of the sleeve 90 degrees from the stapled edge using 4 1/4" JT21 staples per stake. The stake ends should protrude 7" below the sleeve, which will be inserted into the ground. Consider pruning the first year trees down to 2" tall around July 1st to promote bushy growth to reduce deer over-browsing and buck rubbing impact as deer prefer to rub branch-less stems.
Plant the 14" ministools or dormant cuttings 10" deep then place sleeve assembly over the planting with the stapled edge facing South allowing sprouts to grow outside if the stem is injured.
See video: Open4st Low Cost Tree Shelter.
See Photos: 2022-DeerProof-WhiteTextileSleeves
Weed Control Options:
Spray glyphosate on the weeds around each tree when they are growing vigorously. Be careful not to over-saturate or penetrate any protective covering on the stem. The ideal date is around May 15 in Grand Rapids, Michigan when the Quack grass is about 10" tall and later in June and/or August as needed. Note that periods of drought will affect the efficacy of weed control. Each tree should have about a 6' diameter of weed free area. Re-treat with glysophate mid-summer and for 2 years as needed.
Stage 3: Harvest or thin trees:
Cut the wide spaced aspen trees in late Fall/Winter after about 5-7 years to fully stock the site to aspens.
Biomass harvesting systems like the Biobaler could be used to thin sucker stands for biomass and release higher value trees for veneer or lumber markets.
For more information see: Intermediate Treatments and How to Manage Aspens.
STRATEGY 2: Three Stage 'Deer Proof' Aspens via 8' Rooted stock:
1st stage - Start 8" dormant cuttings 3/8" or greater in diameter in a nursery to attain at least 8' tall, preferably in one growing season. Plant the cuttings 6" to 8" apart in rows 3' apart. Ideally, the stock should be 1/2" at 4' tall to be resistant to deer snapping them with their teeth. This is referred to "Deer Proof" stock. They will be pruned back to a total length of 6.5' (roots and shoot) and replanted into the field trial the following Spring. Grow enough material in the nursery to process as cuttings for the next year to avoid growing dedicated stool beds. The second and third steps are the same as Strategy 1 above. Field planting these large trees by stapling one 4' bamboo stake to the stapled 3' fabric, then plant the tree 12" deep, drape the stem with the sleeved/stake combo with pre-loaded tension against the tree stem that serves as another stake. See photos: 2023-Post4.1-polePlanting.
Sample No-Till Upland Planting Scenario:
Obtain soil tests to understand the site fertility and soil texture. Also dig several 2'-3' pilot holes with a 6" auger to assess the soil structure. Consider consulting your local extension office for recommendations.
Consider planting several small edge test plots (e.g. 4-8 trees per plot) with different clones one or two years in advance of a larger planting. This should help you understand weed, pest and animal issues before any larger scale effort.
Use 18" 1-0 dormant rooted ministools with at least 6 different clones or varieties.
Plant aspens on 40' centers to be harvested in 5-7 years then 20 every years, or plant 150 aspens per acre intermixed with another species (e.g. Hybrid Larch) to be converted to aspen and re-harvested every 20 years.
Aerate each tree planting area with a garden fork, plant the ministools 10" deep with a Jim-Gem KBC Bar then add 1 cup of peat moss or coconut coir before covering the roots and firming the soil.
Protect the trees with an 18" fabric tree shelter (see above) or an 18" plastic tree tube supported by 2 4' bamboo stakes.
Spray glyphosate on the competing vegetation when they are growing vigorously. Be careful not to spray herbicide onto the aspen stems. The ideal date is around May 15 in Grand Rapids, Michigan when the Quack grass is about 10" tall and later in June and/or August as needed. Note that periods of drought will affect the efficacy of weed control. Each tree should have about a 6' diameter weed free area. Re-treat with glyphosate mid-summer and for 2 years as needed.
Cut back the trees to 2' tall during mid-Summer (e.g. July 15th in Grand Rapids, Michigan). This should promote a multi-branched tree to discourage buck rubs on a smooth main stem and protect against over browsing. It may also promote a larger diameter root collar and sturdier tree to help withstand severe buck rub damage.
Measure survival and heights after the first growing season and diameter every 3rd year thereafter. Also note significant disease, insect and animal damage. Store data in a database (see: Using the r4st Database) and post online with a summary and relevant observations.
Recommended Reading:
Precautions before planting: Aspen Storage and Planting Notes
Grower's Guide for Hybrid Poplar Plantations for Biomass Production