FOREST PRODUCTIVITY
Publication Series
November 2012
WSF&NR 12-FP-6
Establishing Southern Pine Plantations – Site Preparation Options
November 2012
David Dickens – Forest Productivity Professor and David Moorhead – Silviculture Professor
The University of Georgia Warnell School of Forestry and Natural Resources
Some form of site preparation is needed to establish a southern pine (loblolly, longleaf, slash,
Virginia, shortleaf) plantation. This is the case whether the site was just harvested of the last crop of
trees, a pasture site, or a former cropland site. Southern pines are shade intolerant, therefore requiring a
“free to grow” environment. Southern pines, like all plants have three major requirements: water,
sunlight, and nutrients. The site preparation activity(ies) should optimize all three of these requirements.
In most cases competition control is the most important objective in preparing a site for planting
seedlings of any southern pine species. On soils that are somewhat poorly to very poorly drained (many
Atlantic and Gulf Flatwoods soils), mechanical bedding is often needed to ensure adequate seedling
survival and early growth. Some site preparation activities can also enhance the plantability of the site
by reducing or moving logging debris.
Types of site preparation include: mechanical (chopping, disking, bedding, 3in1 plowing,
subsoiling, and ripping), chemical (using soil, foliar, or soil and foliar active herbicides) or combinations
of mechanical and chemical treatments.
Table 1. Advantages and disadvantages of mechanical and chemical site preparation
Mechanical site preparation
Chemical site preparation
Generally improves site plantability
Generally does not improve site plantability
(without a burn)
Negligible to moderate competition control (short
Good to excellent competition control (longer
lived)
lived)
Slope limitations
No slope limitations (when aerially applied)
Used for improving soil conditions (ameliorating
Does not improve soil conditions
compaction, aeration, soil moisture status)
Can reduce site productivity with certain activities No soil or debris movement, therefore no adverse
if large amounts of topsoil is moved or displaced
effect on site productivity
Wider window to perform mechanical site prep
Narrow window to optimize chemical site prep
Historically, when preparing a site whose last crop was trees (cut-over sites); the first types of
site preparation for pine plantation establishment was prescribe burning the site or chopping and
burning. Burning generally improves site plantability but can vary greatly intensity and effectiveness.
Chopping effectively reduces logging debris and residual trees to ground level, is often followed by a
burn, and facilitates site planting. Chopping generally greatly increases hardwood sprouting, in some
cases by over 10-fold, therefore is ineffective at competition control by itself. Disking as a site
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preparation technique was borrowed from farming practices. Disking improves soil tilth in the first 3 to
8 inches and serves as a short-term form of competition control, but is not recommended for slopes >
8% or somewhat poorly to very poorly soil drainage classes. Bedding site preparation came along in the
late 1960’s and caught on in the early 1970’s. Bedding, like disking, improves soil tilth in the bed and
also improves near-term nutrient availability by churning organic matter and topsoil in the bed. Bedding
is usually prescribed on somewhat to very poorly drained soils to raise the root zone above a perched
water table and increase site plantability. Shearing, rootraking, and windrowing or more recently piling
debris can greatly improve site plantability where there is a high debris level. Depending on operator
care, site productivity can be adversely impacted if one or more inches of topsoil are moved into the
windrows or piles along with all the debris. Shear, raking and piling or windrowing is usually required
prior to disking or bedding. A more recent mechanical activity to come along is 3in1 plowing where
ripping (or subsoiling), disking, and bedding is performed in one pass. This mechanical activity has just
about replaced the shear, rake, pile, or windrow then disk or bedding activities where logging debris
levels are low to moderate and on better drained soils. Chemical site preparation treatments using soil,
foliar or soil and foliar active herbicides have become quite popular since the 1980’s. Numerous studies
in the last 20+ years have shown that on the majority of sites competition control is the single most
important site factor to optimize southern pine seedling survival and growth. The most complete
(volunteer pine and hardwoods or woody, shrub and herbaceous vegetation) and longest lasting
competition control comes with herbicide use. For herbicides to be most effective, dosage and timing
are critical. More recently (early 1990’s) tank mixes of herbicides to control a broad spectrum of
competing vegetation has proven to be very effective. Since the late 1990’s fall application of tank
mixes with a pre-emergence herbicide added to the formulation has further improved competition
control, seedling survival, and growth.
Choosing the right site preparation treatment along with the tree species to plant, the seedling
source (for genetic and seedling quality/size attributes), and spacing are considered to be the most
important forest management decisions for several reasons. These include: (1) total cost per acre since
the establishment phase is usually the most costly expenditure in a rotation, (2) landowner financial
constraints, (3) wood and non-wood (i.e. pine straw) products grown, (4) rotation age and number of
thinnings, (5) stand uniformity, and (6) future stumpage prices. Choosing the right site preparation
prescription is a case by case call. There is no single blanket site preparation prescription. To choose the
best site preparation prescription question what is the single most limiting factor to early seedling
survival and growth. Is it competition, soil moisture status (excessive, insufficient), nutrient availability
(i.e. phosphorus deficient somewhat poorly to very poorly drained Flatwoods soils), or soil tilth (i.e. a
hardpan).
Using recent UGA Warnell School of Forestry and Natural Resources research study findings,
chemical (herbicide use) site preparation produces more wood, more valuable wood, and a higher
revenue per acre (Table 2) in many cases over conventional mechanical treatments. The chemical site
prep treatment also yielded a higher rate of return (8.9%) than the chop and burn (7.9%) or shear, pile,
disk (7.2%) site preparation treatments over a wide variety of sites (using Georgia 2nd quarter 2011 pine
stumpage prices). When in doubt, get advice from a reputable professional forester, Cooperative
Extension Service, and/or state forester as to the best site preparation practice for your land.
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Table 2. Loblolly pine wood yields and value per acre for three site preparation treatments through age 23-years
Site prep
Site prep and Pulpwood Chip-n-saw
Pulpwood
Chip-n-saw Total value
treatment
plant
cost/acre ($)
------ tons/acre --------------- $/acre --------$/acre
Chop, burn
172
59.5
35
535
525
1060
Shear, pile, disk
224
61.5
42
547
628
1175
Herbicide, burn,
215
79
64
705
972
1677
herbicide
Pulpwood = 4.6 through 8.5” dbh trees and chip-n-saw > 8.5” dbh trees. Pulpwood @ $9/ton and chip-n-saw @
$15/ton using Timber-Mart South 2nd qtr 2011 prices.
Warnell School of Forestry and Natural Resources
Athens, Georgia 30602‐2152
Telephone 706.542.2686 Fax 706.542.8356 In compliance with federal law, including the provisions of Title IX of the Education Amendments of 1972, Title VI of the Civil Rights Act of 1964, Sections 503 and 504 of the Rehabilitation Act of 1973, and the Americans with Disabilities Act of 1990, the University of Georgia does not discriminate on the basis of race, sex, religion, color, national or ethnic origin, age, disability, or military service in its administration of educational policies, programs, or activities; its admissions policies; scholarship and loan programs; athletic or other University‐administered programs; or employment. In addition, the University does not discriminate on the basis of sexual orientation consistent with the University non‐discrimination policy. Inquiries or complaints should be directed to the director of the Equal Opportunity Office, Peabody Hall, 290 South Jackson Street, University of Georgia, Athens, GA 30602. Telephone 706‐542‐7912 (V/TDD). Fax 706‐542‐2822
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