Pine Management

There are numerous species of pines throughout Virginia. Loblolly, shortleaf, white, and Virginia pine are the most common, but other species are both important and commercially valuable. Virginia's pines are early successional species and benefit from full-sunlight during growth and development. Although the pines can be reproduced either through natural or artificial means, a planned program of selected forestry practices greatly improves long-term management options.

Some common practices used with pines are: Site preparation, planting, release, thinning, and pruning.

Site Preparation

In many cases, it pays to reduce competing vegetation and logging debris before planting, or natural regeneration. Initial costs of treatments must be weighed against increased production and future economic gains, and on-site conditions that might be influenced by selected treatments. Often, too extensive a site treatment is uneconomical, or may actually decrease soil-site productivity. Ideally, site preparation reduces competition without removing or destroying top soil and organic matter. Classes of site preparation are mechanical, prescribed burning, and chemical herbicides. Use of practices differs according to conditions on cutover lands or open fields.

Mechanical Site Preparation can take many forms, but several of the most common are drum chopping, shearing or bulldozing with a KG blading, or disking on cutover lands; and plowing, scalping, or mowing on open lands.

Cutover Lands

When large amounts of small diameter trees or brush are left after harvest, a rolling drum chopper can effectively reduce this woody competition with a minimum of soil disturbance. If trees are scattered or too large to chop, treatment is by other methods. Drum chopping can be used alone, or in combination with prescribed burning.

Shearing or KG blading is used to remove large numbers of stems that are too large to disk or drum chop. Most debris that would hinder planting is removed. Debris is piled in windrows or piles. Frequent gaps should be made in windrows for access by planting crews and fire fighting equipment. Large piles and windrows deteriorate slowly. They also occupy more planting site. Use care to keep the windrows narrow, piles small, and to keep topsoil disturbance at a minimum.

Disking is an effective method of cutting and turning under low brush and smaller logging debris. Similar to plowing, disking also has benefits of incorporating organic material into mineral soil, breaking up compaction and increasing infiltration of water into soil. Care must be taken to minimize erosion.

Open Lands

Early successional pine species are most commonly planted on open lands. Often these sites are occupied by dense covers of grasses, and other low forms of vegetation. This vegetation both competes with new trees for moisture and nutrients, and harbors large populations of rodent animal species that can be destructive to newly planted trees.

Control of competing vegetation on many of these areas is essential to good tree seedling survival; also, to early growth and development.

Conventional plowing of open fields prior to planting reduces grass competition and incorporates organic material into mineral soil. Care must be taken to minimize erosion.

Scalping is a very specialized form of plowing. Only a limited corridor of competing vegetation is removed from the path of the planted rows. The practice can be applied using conventional farm plows or special attachments on planting machines. The threat of soil erosion is minimal with scalping if rows are on the contour.

Mowing of open fields prior to planting is beneficial on areas more occupied by weeds and fine grasses than those of coarse, dense, more competitive vegetation. Mowing affords temporary reduction of competing vegetation, exposes rodents to predators, and improves planting efficiency.

Prescribed Burning Site Preparation

Prescribed Burning Site Preparation is a very effective tool in reestablishing forest stands, particularly pines. It is most commonly associated with loblolly pine, but is very useful with other species. It is by far the simplest and least expensive method of preparing planting sites.

Prescribed burning has a three-fold purpose:

  1. Remove dense logging debris and expose more plantable area.
  2. Control competing underbrush and other biological agents, thus improving planting bed conditions and opportunities for survival, early growth, and development.
  3. Provide heat sufficient to kill the overstory competition, and thus reduce the overhead shade and competition for moisture and sunlight.

Prescribed burning is a highly technical job requiring a knowledge of fire behavior, suppression techniques, and the environmental effects of fire. Prior to its use, a prescribed burning plan should be prepared. The actual fire should be skillfully applied according to plan.

Landowners (or designated agents) assume the responsibility for starting the fire; and for any damages occurring from the prescribed burning operation.

Chemical Herbicide Site Preparation

Chemical Herbicide Site Preparation is another effective means for creating site conditions suitable for forest regeneration. Herbicides can be used singularly, in mixtures, or in combination with prescribed burning for desired results. Prescriptions for use should be developed by a professional forester.

When herbicide application is used for site preparation, work can be performed during the spring, summer, or early fall depending on site conditions and prescriptions. Materials, formulations, and rates are selected to meet conditions of season and vegetation growing conditions, and environmental considerations.

Site preparation using herbicides minimizes the problem of soil erosion and potential site degradation. Site recovery is rapid following application. Grasses and herbaceous vegetation generally cover the site the first growing season after pine planting. This recovery also has wildlife habitat benefits.

Where appropriate, herbicides can save considerable time, effort, and money. The Department of Forestry coordinates several statewide programs for the benefit of the non-industrial private landowners. Much of the effort involves aerial application.

The Department of Forestry administers a time-tested program that carefully coordinates all facets of forest herbicide research, product safety, regulated business practices, and continuous on-site inspections. The Department contracts with both the commercial applicator and with each landowner using the program. This arrangement provides professional guidance and control throughout each step of the process.

Planting

Pine regeneration can be accomplished through natural or artificial means. Each form has associated site preparation, establishment, and intermediate cultural practices prescribed to meet site, species, and density conditions.

Basically, there are two planting options and numerous variations under each option:

  1. Hand Planting
  2. Machine Planting.

Where sites are open fields, or large well-prepared cutover tracts, machine planting may be the most effective and economical. But, hand planting is more efficient on small areas, where terrain is steep or rough, where stumps are numerous or of large diameter, or where residual logging debris impedes the use of machines.

Hand Planting

Simple equipment is necessary for hand planting:

  1. “dibble” or planting bar (or hoedad)
  2. planting bag for carrying and protecting seedlings.

Seedlings should be planted one tree per hole, upright and no folding of the roots. Root pruning should be avoided in the field since most seedlings are root pruned at the nursery. Pine seedlings should be planted tight so that seedlings cannot be pulled out by pulling on three needles.

Planting Time

For conventional planting of pine seedlings, the most favorable time is during the dormant season (December - March in the Coastal Plain; February - early April in the mountains). Avoid planting when the ground is hard - either frozen or dry; or, when too wet or sticky.

Planting when the soils are in poor condition results in misplanted seedlings, low survival, poor planting production, and poor growth.

Spacing

Before ordering seedlings, decide what spacing to use. No standard spacing can be recommended because of differences between species, site quality, local survival patterns, products desired, or other factors.

Machine Planting

Specific planting machines are not recommended because of variation of conditions throughout Virginia. Fortunately, a number of good machines with specialized features are available from the Department of Forestry for private rental. One or more will be particularly suited to each site.

As with hand planting, protecting seedlings from drying out during machine work is very important. Seedlings must remain covered and the roots kept moist. In all planting, check frequently to assure that seedlings are being planted properly.

Release

Once pine seedlings are planted and survive, they require sufficient sunlight and nutrients to become firmly established. Often surrounding vegetation competes severely and must be controlled (until pine seedlings attain 4-5 feet in height). Control of competing vegetation is called release. Release can be accomplished by mechanical or chemical means, or by a combination.

Mechanical Release

Mowing, brush cutting, or hand chopping are all mechanical ways to keep competing vegetation under control.

When planting open fields, provisions can be made to accommodate later mowing for grass control. Planted rows should be spaced at least 2-3 feet wider than the width of tractors and mowers. Depending on the tree species and expected product, mowing might be beneficial (Christmas trees) for 3-5 years. Frequent mowing is more likely the first year and is dependent on growing conditions. In following years, one mowing each growing season (performed in August) should be sufficient until the trees average 4-5 feet tall. After that, mowing should be discontinued unless a neat appearance is an important objective.

Brush cutting or hand chopping can be used effectively in pine plantations established on cutover forestland where hardwood sprouts are competition. Chopping may be used in combination with prescribed herbicides for greater effectiveness. To maximize economy, do not hand release more than necessary to keep the pine seedlings “free-to-grow.”

Chemical Herbicide Release

Applying chemical herbicides is an effective and sometimes necessary means of controlling unwanted competing vegetation from planted pines. Use of herbicides for pine release normally occurs when pine seedlings are 1, 2, or 3 years old. Chemical control (release) operations are normally conducted during the summer and early fall using “selective” materials that will suppress competing brush, but have little or no adverse effects on planted pines. Chemical release can be performed either from the ground or from the air.

There are several general methods commonly used in applying herbicides for release. These are:

  • Strip spray is the application of a path of herbicide about two feet wide along the line of planted seedlings.
  • Spot spray is the application of herbicide confined to an area surrounding each seedling.
  • Broadcast spray is the application of herbicide to the entire planted area. This can include aerial spray.
  • Aerial spray is the application of herbicides from above the tract normally using helicopters and state-of-the-art technical support equipment.

The Department of Forestry coordinates several statewide programs each year for the benefit of private landowners (see Chemical Herbicide Site Preparation).

When seedlings become firmly established (either without or with release) they can successfully compete with surrounding vegetation. Initial care for the first few years will provide a lifetime of trees.

Thinning

To maintain a competitive advantage on the best trees (particularly when high quality sawtimber and high seed production for wildlife are desired products) most pine stands benefit from thinning. With some pine species, particularly loblolly pine, periodic thinning is a requirement. There are several forms of thinning, but most can generally be classified as pre-commercial or commercial. The BEST trees are retained as crop trees. Poorer trees are removed first and subsequently in later thinnings.

Pre-commercial Thinning

Early successional pines frequently seed naturally into areas in abundant numbers. Tree numbers exceeding 5,000 stems per acre are not uncommon. This overstocking can have serious consequences in early development of natural origin pine stands. Effects of overstocking vary with tree species.

When recommended, overstocked pine stands should be pre-commercially thinned at an early age. This minimizes costs and insures maximum growth response. Trees should be small enough (with loblolly pine 6-8 years) that stems can be cut with small equipment. Pre-commercial thinning can be “selective” (thinning around individual trees), or in strips where swaths are cut with mechanized equipment.

Pre-commercial thinning can shorten the time interval to the first commercial thinning. The need for thinning varies by site, species, density, and uniformity of tree heights.

Commercial Thinning

Once pine trees reach the minimum commercial size (pulpwood), thinnings can be conducted at a financial profit. BEST trees should be retained as before to accumulate quality volume and accelerated value. Poorest trees or those less valuable to produce objective benefits should be removed first. Thinning can:

  • Maintain tree vigor and resistance to insects and diseases.
  • Enhance wildlife habitat.
  • Obtain early financial returns to offset establishment and operational costs.
  • Concentrate growth on the fewer BEST trees.
  • Increase the rate of return on the forest investment by developing large trees that command high stumpage prices.
  • Salvage trees that periodically die to various causes, including suppression.
  • Provide periodic income.
  • Provide better access for fire equipment.
  • Increase forest beauty.

Commercial thinnings can take many forms. Prescriptions will vary by species composition, site quality, tree size and quality, current rate of growth, incidence of insect and disease, tree defects, available markets for forest products, and of course the landowner's objectives. Final spacing of the desired number of trees will be a function of all the factors discussed. Various site and tree measurements will assist in determining the numbers associated with the thinnings.

Basically, commercial thinnings can be categorized as “selective” and “corridor.” The numerous variations of selective thinning all work on the principle of individual trees. Corridor thinning can refer to row thinning in pine plantations, or road thinning in natural stands of randomly established trees. In most cases today, combinations of corridor and selective techniques are performed to accommodate the high level of mechanization.

Pruning

The economics of pine management often prevents the practice of tree pruning from being applied. In some tree species, pruning is not necessary nor practical. In others, such as white pine (persistent limbs), pruning assists with the production of “knot-free” high value lumber.

Goals in pruning are usually confined to developing maximum quality within the first 16 foot log (the largest and most valuable cut in timber trees). The objective is to remove limbs early when trees are small so that clear, knot-free wood will be produced over future diameter growth. Only final “crop trees,” with a few insurance trees, should be pruned.

Pruning usually begins when trees average about 4“ in diameter at chest height. It is commonly performed in two or more operations. Care should be taken not to prune above 2/3 the total height of the tree.

Proper tree pruning takes skill and proper care and attention to details. Pruning cuts should be made with specialized saws and pruning tools, not with an axe. Limbs should be removed close to the trunk, but just outside the branch collar (raised area between trunk and limb). Improper tree pruning should be avoided. There is no need to use tree wound dressings.

Pine management is not difficult, but it is complex. There are numerous biological, economical, social, and business considerations to be measured, analyzed, compromised, and decided upon. Even legal provisions need to be considered in particular cases. Good plans made well in advance, then methodically implemented in a business-like approach will assist landowners in maximizing returns for multiple objectives from forestland. Professional foresters are available and should be consulted to assist with analyzing, planning, and implementing the various forestry options introduced.

Descriptions of applicable laws requiring reforestation under certain conditions and cost share programs available to landowners to help cover the costs of reforestation are found in the section titled Cost Share, Laws and Taxes.

Additional information

Online publications and information are available from Southern Regional Extension Forestry.