A CONDENSED GUIDE TO POPLAR MANAGEMENT: WHY, WHERE, WHEN AND HOW |
SCOTT PAPER LIMITED
By: Peter McAuliffe
Revised September 1993 Poplar management is an enigma in B.C. because it is so unlike traditional coniferous management. In a province where foresters have struggled for decades to eliminate all hardwood, it is a challenge for managers to remain open-minded, and to fully realize the potential of poplars.
The first barrier to understanding poplar is the terminology. The following is a table of (popular) poplar terms:
| (1) poplar | any tree of the genus Populus, including back cottonwood, balsam
poplar, aspen, eastern cottonwood, plus European and Asian species and all the interspecific hybrids between them. |
| (2) cottonwood | Populus trichocarpa, or "black cottonwood" is the native poplar species of Western North America. |
| (3) hybrid | the offspring (or progeny) resulting from the sexual reproduction of two parents from differing breeds or species. |
| (4) clone | genotype; a plant or group of plants, all with identical genetic make-up,
arising by vegetative (asexual) propagation from one individual plant. |
| (5) cultivar | a plant or group of plants, arising by vegetative propagation or sexual
reproduction from a single clone or group of closely related clones. |
| (6) cutting | any segment cut from the stem or branches of a tree. A cutting has no
roots. Normal cutting dimensions are 45cm by 10-20mm basal diameter. |
| (7) whip | a long cutting; generally 1.0 - 2.0 m cut from the top of a small tree or stump sprout. All side branches are removed.The basal diameter is between 10 mm and 20 mm |
| (8) rooted set | a one- or two-year-old plant started from a cutting, lifted with roots
intact. The roots are pruned back to fit into an anger-bored hole approximately 30 cm in diameter. |
| (9) stool | the roots and stump of a tree that has had the main stem removed from it. |
Mostly because of poplar's remarkable growth rates. At a time when world demand for pulp is racing ahead of projected supply, poplar can supplement existing fiber sources quickly. In addition, there is a lot of suitable land in B.C. because poplar displays broad site adaptability and silvicultural compatibility with other species. Because poplar can be grown quickly and over a short rotation, its fiber will be available sooner and returns on investment will be realized earlier.
Manage for poplar because it will thrive on active riparian ecosystems where all other commercial tree species struggle. In active river floodplains a short-rotation crop is best because it likely can be harvested before the river changes its course again. It can be managed without relying on chemical brush control. Being the fastest growing "weeds, the poplar, once established, will not be overtopped by any brush or non-commercial trees.
Do it for the money. Poplars are a cash crop with an attractive pay back period. Whip plantations are merchantable by the age of 25 years, with possible growth rates between 10 m3 and 20 m3 per hectare per year, depending on site and management inputs. Intensive management (agricultural system) yields over 30 m3 per hectare per year on a twelve to fifteen year rotation.
Do it because there are growing domestic and offshore markets for poplar. Scott Paper has been buying poplar at fair market price for four decades and will continue to do so for at least four more. The price that Scott has paid for poplar has increased over 100% over the last decade and is likely to continue to climb. If you are holding land that is brushed in or covered with low-value hardwoods, converting to poplar is the most economical way to get that land back into production.
Where and when to manage for poplar?
Plant poplars on moist to wet sites with available ground water throughout the growing season. Poplars prefer rich, well-drained soils with neutral to slightly acid pH.
Plant poplars on annually flooded lands where other commercial tree species cannot survive. Poplars can tolerate four to six weeks of flooding providing that the water is moving and carries some oxygen in it.
Plant poplars on moist and well-drained upland sites (they do very well on loess and silt cappings over marine sediments) if the market demand for poplar is strong and if the price is attractive.
Plant poplars on highly productive sites where rapid regrowth of brush species make it difficult or excessively costly to manage for more traditional species. Plant poplars where insects or diseases preclude coniferous crops and where the use of herbicides is environmentally unacceptable. Alluvial sites on river flood plains usually fit this description.
Plant poplars on brushed-in lands because the cost of rehabilitation will be less than for coniferous crops. With rapid early growth, poplars are "free-to-grow" within two to five years of establishment.
Although poplars grow best on very rich alluvial sites, they will grow on a wide range of forest sites and still produce impressive volumes in a short time. Poplars can be planted to improve wildlife habitat, for soil conservation, for streamside protection, or as landscape trees or windbreaks.
How to manage for poplar?
If you are starting with a pure stand of cottonwood or a mixed stand with a minimum of 200 well-spaced stems of cottonwood per hectare, then reforestation of cottonwood will likely be done by mother nature. There is no cost for natural regeneration, but you will be very lucky to get just the right stocking and density. The problem with cottonwood natural regeneration is that it comes "all or nothing"; cottonwood regenerates at 10,000 - 30,000 stems per hectare under favourable conditions, but the species is so strongly self-thinning that the density will decline steadily over a rotation without any stagnation of dominant crop trees. In stands with fewer than 200 well-spaced stems of cottonwood per hectare, steps must be taken to enhance natural regeneration. This can be accomplished by logging or clearing early in the year after the frost is out of the ground but while the soil is moist (at field capacity) and before plants start to grow. Natural regeneration can be enhanced by moving equipment back and forth over a logged block repeatedly to break up twigs of cottonwood and to press them into the ground where they can develop a good root system. This may also be accomplished during skidder logging by trying to move to new skid trails as often as possible.
If you don't have enough cottonwood in your stand before clearing or logging, or if you cannot log in early spring, you must resort to artificial regeneration, or planting.
On undeveloped forest sites with an advanced cover of shrubs and potential brush problems or on recently denuded lands with heavy logging residue, it is best to plant 1.5 to 2 meter whips. A whip should have its terminal bud intact and a large caliper (basal diamter between 10 and 20 mm). Whips have no root system, but rely on roots that develop from beneath the bark and grow quickly to allow the developing plant to obtain water and minerals from the soil. Whips do well on recently logged or cleared sites providing brush and/or other deciduous trees have not already gained control of the site. Pre-planting site preparation such as brush blading or chemical weed control will do much to ensure survival and rapid growth of a whip plantation with no brush control expenses after planting, although such treatments will not be required if planting follows immediately after logging or clearing.
The major drawback of whip plantations is that their performance in the first growing season is somewhat variable and dependent on weather conditions following planting. If the plantation receives lots of rain water until the whips have developed a good root system, trees will grow between 50 and 100 cm in the first year. During years with dry, hot weather following planting, trees may go into a planting "check" and will grow only 10 - 20 cm in the first year because they are struggling to develop a root system to supply the water demands of the current years foliage. Poplar trees in this slower growth class can be in danger of being overtopped by brush species and if this occurs, the shade-intolerant poplars are in serious trouble. One can improve the first year performance of whips by cutting them early and storing them at -5 to +2°C in the dark and wrapped in plastic for two to four weeks. This technique will delay spring bud flush, soften the stem bark and cause the adventitious roots to begin to grow through the bark near the bottom of the stem. At the time of planting, trees with roots already initiated and buds retarded have a much better chance of maintaining desirable root-shoot balance through the first growing season.
The advantage of whip plantations are that they require little site preparation or weeding costs and that trees, being one meter or more tall at the time of planting, have a height advantage over brush competition.
Whip planting may be used to enchance the stocking of naturally regenerated stands of cottonwood or to fill in holes in natural stands. Whips are easy to dibble plant on silty soils and no screefing of duff is required.
On sites with high brush hazard, a sanitation spacing or weeding operation may be required after the first or second growing season to remove any plants that are threatening crop trees. This procedure is best performed with spacing or clearing saws.
An intensive poplar silviculture regime can be employed for very productive sites where the higher levels of investment can be justified, and for accessible lands close to markets where the extra costs of site preparation and weed control can be offset by the realization of faster growth rates and an earlier harvest date. Previously cleared lands such as abandoned agricultural property are suitable for this intensive short-rotation system as the initial land clearing and site preparation costs will be lower.
For the intensive silvicultural regime, an increased emphasis is placed on site prepartion. All slash and stumps must be removed from the site. The land must be accessible to a farm tractor with tilling attachments for weed control over the first three growing seasons. Although the costs of stock and planting for 30 - 50 cm cuttings is lower than the comparative cost of whips, the high costs of site prepartion and weed control make the intensive silvicultural regime three to four times more costly than planting whips.
The greatest advantage of cutting plantations is that the extraordinary growth rates of exotic hybrids may be capitalized upon. American researchers have recorded productivities of 59 m3 ha-1 yr-1 of gross stem volume, based on data from a four-year-old plantation1.
Other stock types may be used when brush competition is severe or for re-planting where plantation trees are already 3 - 4 m tall. For example, 2 - 3 m rooted sets can be planted in auger-bored holes to get very rapid initial height growth. However, the high costs of planting rooted sets have limited their use to date.
How do I get poplar planting stock?
The most inexpensive and easiest way is to find a naturally regenerated stand of poplar that is 3 - 5 meters tall and to cut off the top 1.5 to 2 meters of vigorously growing trees. These should be trimmed to length, the side branches pruned off, and stored in plastic at -5 to +2°C for up to six weeks before planting (although they may be planted immediately as well). If you want genetically superior stock or you don't have a place to collect wild stock from, Scott Paper may be able to provide stock at a rate which covers the growing and handling costs. The current price for 45cm poplar cuttings is $0.35 each.
How many trees do I plant?
800 stems per hectare is target spacing for a pulpwood rotation of 25 years, with a minimum spacing of 500 stems per hectare. Such a stand will yield roughly 300 - 400 m3/ha of pulpwood at 25 years. Expect a very high survival rate of 90 - 100%, so plant at 800 - 900 stems per hectare.
When to collect and plant poplar?
Collect poplar 2 - 6 weeks before planting, while leaves are off and plants are dormant. Plant poplars in early spring after frost is out of the ground and before stock begins to grow.
Is that all there is to it?
No! Sometimes you can plant poplar and leave it alone to do its thing, but you have to watch it carefully. A poplar plantation may require a weeding in the first year or protection against animal browse, insects, diseases, etc. Plantations established from cuttings can be especially vulnerable to the above pest agents.
Where can I find out more about poplar?
There are some good texts and articles in the literature, though most studies deal with short rotation intensive culture for biomass (3 - 10 year rotations). Scott Paper now has over 30 years of experience managing poplar. You can call me anytime for advice. My number is 520-9284.
References
"High Yield Poplar Plantations in the Pacific Northwest" P.N.W. 356 W.S.U. Extension Service 32pp 1990.
The Culture of Poplars in Eastern North America. Dickman, 1983.
A Grower's Guide to Hybrid Poplar 148pp. Ontario Ministry of Natural Resources ( 1991 ).
HYBRID POPLAR AS A CASH CROP: COSTS ~ BENEFITS
The following figures represent the average costs and revenues for growing a plantation of hybrid poplars on medium quality farmland in the Fraser Valley, excluding land purchase or rent. The analysis assumes that the grower already owns cleared acreage suitable for poplar growth.
Growing cost estimates are given for two scenarios and harvesting cost estimates are given for four scenarios. The "contracting out" scenarios assume that the grower has no time or equipment to do the work but has the capital to hire contractors. The "Do-it Yourself" scenarios assume that the grower has time and some farm equipment (tractor with implements) to do most of the growing and harvesting work. Costs and revenues are estimated in 1992 dollars. The figures in Tables 1 & 2 are not discounted.
Growing costs for the second crop of poplars will be lower because the stumps left after the first harvest will re-sprout on their own and therefore planting and stock costs will be minimal in the second rotation. Furthermore, the stump sprouts will grow faster than the cuttings originally did, so yields will be higher on the second rotation and weed control costs will be lower.
To calculate the net income for your property using Table 2, multiply the net income per acre by the number of acres in production. For example, if you manage a 10 acre parcel for poplar production using the L2 "Do-it-Yourself" Scenario (see Table 2) you would invest $3,000 over three years to establish your plantation and after 15 years you would have a crop worth $78,000 (for pulp logs delivered to the mill). Even after you deduct logging and hauling costs ($24,000) and growing costs ($3,000) you are still left with $51,000 profit.
If you do not have property already, you will have to add in land purchase or land rental costs to the analysis. At a land cost of $100.00/ac-yr, scenarios L1 and Bl ("Contracting Out") are marginally viable, but you can still earn good revenue if you do some or all of the work by yourself.
The best-case scenario is on cleared and fallowed land owned by a grower who has access to farm equipment and labour that he or she wishes to employ during the slow winter months to supplement farm income. Additional tax benefits may also be realized when property owners derive income from their lands.
Once again, please note that the above figures have not been discounted to the present. Discounting costs and benefits to present values for the L2.
"Do-it-Yourself" scenario using the 7% interest rate gives the following values:
$78,000 Gross Revenues
- 24,000 Harvesting Costs
$54 000 Net Revenues in 15 Years
$54,000 discounted for 15 years has a present value of $19,572. The $3,000 growing costs discounted for 0-3 years has a present value of $2,882.
$19,572 Revenues
- 2 ,882 Costs
$16 690 Net Present Value
Allowing for land rent at $100/ac-yr discounted for 15 yrs to the present land rental costs are $9,100 for the 10 acre parcel.
In this case, the net present value of the project is still $7,590, even after land rents are considered.
There has been no attempt in this analysis to quantify the variability in costs, revenues, or yields. Pulp prices are fairly stable, climbing slowly and steadily. Yields vary widely depending on site quality, planting stock, and intensity of management. With quality hybrid planting stock and good management, consistent yields can be obtained. The largest variables are the costs of growing and harvesting. These depend on current labour and machine rates and on the ground conditions and accessibility of the property. These variables must be considered with risk factors in the economic analysis.
Scott Paper Foresters are available to inspect properties and to review proposals for accuracy and feasibility.
Scott Paper Limited is anticipating shortages of local market wood in the future and would like to encourage more local growers. To this end, Scott Paper Limited is interested in developing growing agreements with Fraser Valley landowners for guaranteed future supplies of consistent local product. In return, Scott Paper Limited will provide advice, on-site assessments, and growing stock at cost. Scott Paper Limited can guarantee a future price above market value in exchange for a commitment of sale for wood grown (right of first refusal).
Peter McAuliffe,
Silviculture Operations Forester.... 520-9284
OR
Ken Stenerson,
Woodlands Manager........................520-9209
MAIL ENQUIRIES:
P.O. Box 760
New Westminster, B.C. V3L 4Z9
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