Short Rotation Woody Crops Operations in the Industrial South

Joe Cox, Champion International, Cantonment, FL

Abstract

Short Rotation is a relative term. Natural hardwood stands represent a significant resource of southern lands. Industry needs to identify treatments that will shorten rotation lengths in natural hardwood lands. Fertilization and stocking control hold the most promise. We hope to shorten the rotations for natural from 40 years to 20 years and to double the growth rate.

In hardwood plantations, we need species site trials to determine what to grow where. The best silvicultural treatments need to refined and developed -- weed control treatments; fertilization rates, timing, and delivery mechanisms; insect monitoring and control treatments; and irrigation methods and monitoring systems.

Along with the silviculture, we need to develop the genetic resource. Breeding and testing of current sources, identification of new sources of genetic material, and hybridization of sources all hold promise for developing trees to plant under SRWC regimes. Humankind will realize the full potential of our genetic resources when we learn to clone the best genetic material. Industry needs to develop operational scale vegetative propagation techniques for trees that do not readily regenerate through vegetative means.

Overshadowing this entire discussion, industry has to pay its own way. To determine if SRWC will pay, industry needs information on wood quality characteristics, and growth and yield information. We feel that SRWC will pay its own way, we need good numbers to convince the people minding the purse.

Introduction

To start off, I will limit my comments primarily to hardwood stands. Short rotation is a relative term. In hardwood plantations, short rotations may be as few as 3 and as long as 10 to 12 years. The rest of this meeting and our field trip demonstrate the potential of plantations. One other area in the South that needs to be mentioned is natural stands.

Natural Hardwood Stands

Natural hardwood stands compromise approximately 20% of Champion’s landholdings in the South. I fully expect other industrial landholdings to approximate this number. Champion’s land managers consider hardwood growth rates of 30 to 50 cubic feet per acre per year and rotation lengths of 40 years to be realistic.

If we could identify treatments that would allow us to grow 100 cubic feet of wood per acre per year, 20 year rotations for natural hardwood stands would become feasible -- short rotations.

Mother Nature provides us a bounty of regeneration whenever we disturb sites. On most sites, plant life emerges with such force and vigor, that you may not want to stand still for fear of being overwhelmed. The problem is too much regeneration. As wise land stewards, our challenge is to manage this regeneration to grow wood in a form we may utilize for mankind’s benefit. These stands may take twenty or more years to sort out which stems will survive to become large enough to become useful to humankind. Treatments to hasten stand development hold the most promise in managing natural hardwood stands. To put words around this, our goal as industrial foresters, is to grow 100 cubic feet of wood per acre per year. Research in stocking control methods and in fertilization holds the most promise for producing Short Rotation Woody Crops from natural hardwood stands.

Plantations

We have seen exceptional examples SRWC during this meeting. Some of my following points may cover areas mentioned by some of the previous speakers. Here are what some in industry feel we need in the South.

1. Identify species well adapted to grow on sites under plantation culture.
2. Identify the best methods to achieve acceptable weed control in plantations such as:
   1. Cover crops;
   2. Herbicides and application methods;
   3. Mechanical methods.
3. Identify the appropriate fertilization regimes for each site. Research issues include:
   1. Sources of nutrients;
   2. Fertilization rates;
   3. Application methods;
   4. Interaction of fertilization and stocking levels.
4. Identify the appropriate methods to monitor and control damaging insects.
5. Develop irrigation methods and water management regimes such as:
   1. Methods to monitor the moisture stress in the irrigated area;
   2. Scheduling the water applications;
   3. Methods to monitor water demands over time and their impact on tree growth.

Tree Improvement

The Hardwood Tree Improvement Program will identify and develop the best sources of hardwood species, hybrids and genotypes to plant. Genetic gains in hardwood tree improvement are difficult to predict due to the little amount of tree improvement work to date. The exception is the Populus genus. Hybridization and cloning within selected sub-genus sections of cottonwoods and aspens are projected to produce volume gains of 30 to over 50% compared to the parental species. Selecting and cloning of the currently available hardwood genetic material will provide good short-term gains. Traditional tree improvement methods will develop genetic materials for further improvement, hybridization and clonal selection for the long-term.

The major steps to accomplish the tree improvement goals are:

1. Identify the hardwoods species that will grow well in the South.
2. Identify and obtain sources of hardwood genetic material. Possible sources:
   1. USFS,
   2. Pacific Northwest,
   3. Midwest/Lakes States,
   4. Europe/Middle East,
   5. DOE/MSU Cottonwood Project,
   6. NCSU.
3. Screen hardwood phenotypes for performance and adaptability. Screening trials serve to weed out obvious poor performers. Clonal and open-pollinated tests, using relatively small samples of each genotype, are used to determine which genotypes warrant further development.
4. Test seed origin or clones for productivity and quality traits that will provide information for field deployment. These tests include the materials that pass the screening stage and are used to develop information for further breeding and hybridization and information for field deployment.
5. Long term tree improvement will use breeding, testing and selection to improve the parental species for inclusion in seed orchards and to produce hybrids and clones. Species that currently cannot be cloned will need improved seed to produce planting stock. Species that can be cloned will require the development of better parents for the production of hybrids and/or selection of clones.

Propagation

Propagation methods are not well developed for many of the hardwood species. Even in cottonwoods and aspens, some of the hybrids are difficult to root. The hardwood propagation research will develop the methods to propagate, on an operational scale, the best material identified in the Hardwood Tree Improvement Program.

Vegetative propagation (cloning) allows for the entire genetic make-up of a single plant to be utilized on an operational scale. Cloning makes possible the reproduction of the rare genotypes that contain the genes for high productivity and other desirable characteristics. Because the entire genetic make-up can be exploited, much higher genetic gains are possible than with sexual reproduction. Cloning alone could result in over 20% volume increase in genetic gain compared to sexual reproduction methods.

The major steps to accomplish the propagation goals are:

1. Assess the suitability of various propagation methods for the desired species or genotypes. Available methods include:
   1. Rooted cuttings,
   2. Air-layering,
   3. Root cuttings,
   4. Micropropagation,
   5. Somatic embryogenesis,
   6. Others as they become available.
2. Determine the factors that limit or promote successful propagation of the desired trees. Many factors affect vegetative reproduction of trees. The genetic effects, environmental effects and physiologic processes require better understanding to make vegetative propagation operational. Areas of research include:
   1. Stock plant and media nutrition,
   2. Rooting and/or tissue culture media type,
   3. Photoperiod effects,
   4. Cold storage effects,
   5. Genetic control of rooting/embryogenesis,
   6. Others as they become available.
3. Develop cost effective operational methods to propagate desired trees. Once methods are developed to clone specific species and genotypes, they must be assessed to determine if they are conducive to the scale and speed of operational systems and are within acceptable financial bounds.

Wood Quality

The goal of the pulp and paper industry’s wood quality efforts is to grow wood with excellent pulp yield and quality. The steps needed to achieve this goal:

1. Identify the range of pulp yields and fiber characteristics for each intensively managed species;
2. Quantify the relationships between intensive cultural activities, genetics, and the environment and their impacts on fiber yield and pulping characteristics;
3. Develop techniques to measure fiber characteristics for clones;
4. Develop reliable Growth and Yield models for hardwood stands;
5. Integrate wood quality research into Hardwood Tree Improvement Program for selecting specific species, families and clones;
6. Incorporate the wood quality results and the Growth and Yield models into decision support models and information systems for analysis of forest to mill system benefits.

File posted on March 17, 1998; Date Modified: February 21, 1999