Forest Biology Research and the 21st Century

Stanley L. Krugman, staff director, and Stephen E. McDonald, research forester, Timber Management Research Staff, Forest Service.

The modem forest manager must be increasingly sensitive to society's changing view of the forest resource. As lands that were forest are devoted to other uses such as agriculture or roads, the forest land base grows smaller. Yet the outlook is not bleak. Much of our forested land is producing at only 30 percent of its capability. So even in the face of declining forest acreage, there is plenty of room for improvement in the use of the land now growing trees. New forest products, such as flakeboard, use trees or parts of them once thought of as waste. Possibly just as important, research is providing new tools that will increase the efficiency of forest management.

New management direction from an enlightened, concerned populace, new uses for forest products, and new management tools, taken together, suggest that the 21st century will be the age of scientific, comprehensive forest management in the United States.

The node of a greenhouse-grown eastern cottonwood develops an axillary shoot and callus tissue in vitro. Such cultures supply starting tissues for research about genetic engineering of specific traits such as herbicide stress resistance.

Selective Tree Breeding

For about 60 years scientists have been studying the genetic makeup of forest trees in the hope of learning how to breed them for faster growth, improved wood quality, improved species adaptability, and greater resistance to disease. Several breakthroughs have already occurred. In southern pines being grown for pulp our scientists have charted growth rates 40 percent above normal in genetically improved stock. Pine ;trains with natural resistance to several native diseases, including fusiform rust, also have been located. But timber management is still hindered by both insect and disease pests and by the poor adaptation of forest trees to a particular ar growing site.

Now that genetics research has identified "super" trees in several commercially important species, breeding programs will enable the production of seed from these trees in quantity. Eventually all reforestation will be done with genetically superior stock. Growth gains of 60 to 70 percent should be possible. Through selective tree breeding, the forest of the 21st century will have increased resistance to pests.

The New Biotechnology

Trees are so big and take such a long time to reach reproductive maturity that improving their genetic makeup through conventional methods is time-consuming and expensive. Recent advances in genetic engineering called the new biotechnology will help short circuit the long breeding cycle of trees. Instead of relying on natural selection to improve the gene Pool over centuries, they can isolate the genes that control desirable features in a superior tree and transfer that genetically coded material to ordinary trees.

One method for transferring desirable characteristics uses "Ti" plasmids from the soilborne bacterium Agrobacterium tumefaciens. The "Ti" plasmid is a natural carrier that routinely Inserts new genetic material into Plant cells and normally induces tumors in such plants. Through the new biotechnology, however, scientists can now insert useful genes into the "Ti" plasmid and have the plasmid transfer them into a forest tree. There is good evidence that herbicide tolerance can be incorporated into forest trees directly by using genetic engineering techniques such as the "Ti" plasmids. If our research is successful, trees will grow that can survive exposure to the herbicides used to control competing vegetation.

In the last few years, "osmoprotectant" genes have been identified and isolated in cells of bacteria. These osmoprotectant genes allow certain organisms to cope effectively with drought and cold stress. In the future, it will be feasible to transfer osmoprotectant genes into forest trees, making it possible to extend the commercial range of certain species into areas too dry or cold for them now.

Genetic engineering will help boost growth rates in pines and firs by tricking them into fixing their nitrogen requirements out of thin air! Some tree species can fix atmospheric nitrogen naturally, but this is not a characteristic of conifers. If scientists find a way to pass this capability to pines and firs from species that already possess the trait, they will be making an improvement on nature that would greatly reduce the cost of fertilization and forest management in general.

Soon it will be possible to identify the gene or genes responsible for resistance to certain forest tree diseases. Once identified, such genes can be isolated, reproduced, and transferred into nonresistant forest trees. The resulting decrease in the number of trees now lost to forest pathogens (disease-causing agents) will go a long way toward improving that 30 percent production capability of our forested land.

Understanding Tree Physiology

Advances in the science of tree stress physiology are changing our understanding of how trees resist cold, drought, and disease and insect attack. Such knowledge helps us understand not only how plants function but also why certain plants grow where they do and why they respond to different environments as they do. That information, in turn, helps in the selection and development of trees that are resistant to drought, cold, insects, and diseases.

Stress physiology is related to the broader field of ecophysiology of trees the study of the interactive relationship between trees and their environment. In other words, ecophysiologists try to determine how the environment influences the placement, nature, and function of the plants in it. Forest scientists are only beginning to understand these complex relationships and how they alter them when they manipulate forest stands, for example, by thinning or fertilization. The operating procedure in the past has been primarily to change the forest environment through vegetation manipulation and then observe the reaction of the vegetation.

Ecophysiology examines the direct effects of the manipulation changes in water relations, energy balances, temperature, air movement and relates these factors to the reaction of the vegetation. Through ecophysiology, forest managers can expect to accurately predict how plant life will react to treatments on specific sites. Knowing those reactions in advance will help in choosing management alternatives that precisely match objectives.

New Research Trend

Forest biology research is advancing rapidly along several fronts in the late 20th century. However, the trend is definitely away from research that concentrates on specific treatments at a specific site with extrapolation of results to the whole area, type, or habitat.

Instead, modern measurement, analysis, and the use of computer modeling are enabling forest biologists to measure basic physical factors that control or prompt changes in the forest. Then changes in these factors can be directly related to forest development. Better understanding of these physical forces in the environment and how to manipulate them to change the response of plants will take us to a level of forest management sophistication not even contemplated just a decade ago.