Curtis Moore's hypothesis that plants may be our own worst enemy {''Revenge of the Killer Trees,'' Outlook, July 29} is a radical departure from the views of many respected scientists.

Still unknown is what effect this increasing concentration of greenhouse gases may have on global climate during our lifetime and beyond. We are just beginning to grasp some of the complex factors that govern our climate; a full understanding of their interaction is years away at best. This lack of scientific consensus is not an excuse for inaction; rather we as a global society must strive to practice stewardship of our resources through energy conservation, recycling, prudent management our our forest resources and, yes, the planting of many new trees, shrubs and other plants.

As to the specific role plants may play in the global climate, Moore correctly stated that plants take in carbon dioxide during a process called photosynthesis and under certain conditions they also give off some of this carbon dioxide during respiration. However, a plant does not create new carbon; it only cycles it. Moore also failed to mention that carbon is a basic element of wood. From the moment an acorn sprouts until the mighty oak reaches its demise perhaps 100 or more years later, more and more carbon is stored in its roots, trunk and branches -- carbon which has been removed from the air and soil.

The author's "vicious carbon cycle" is a natural one; plants both take in and give off carbon dioxide as they grow, but there is a net accumulation of carbon in the plant. Thus if carbon dioxide is contributing to global climate change, then plants offer one method for removing much carbon from the atmosphere.

-- Craig J. Regelbrugge The writer is director of regulatory affairs and grower services at the American Association of Nurserymen.

Let's not cut down all those trees planted on Earth Day just yet. Curtis Moore's concerns seem to miss the obvious understanding that in the final analysis, trees are an increasingly essential part of our environment.

Moore has a record of staunch environmental advocacy, and I applaud his intellectual honesty in exploring the "bewildering complex of interactions subsumed under the simple label 'global warming.' " All sides agree that while we can make an educated guess that man's impact on the global atmosphere could lead to a "global warming," we cannot with confidence estimate the size or impacts of climate change or when and where it might appear.

The facts on global warming suggest, therefore, a dual track policy: reduce the scientific uncertainties as rapidly as possible, and take every action which can be justified as an "insurance policy" to reduce greenhouse gas emissions. On the first track, U.S. funding for meaningful climate change research -- roughly $600 million in 1990 and up to $1 billion for 1991 -- is enormous, larger than that of any other nation, at a time when our share of global greenhouse emissions is about 25 percent and declining. On the second track, several Bush administration initiatives are underway which will reduce greenhouse gas emissions by 15 to 25 percent below projected levels in the year 2000. Action and research are proceeding in tandem.

With regard to "killer trees," Moore reports new evidence that as temperatures rise trees actually give off more pollutants than they absorb, contributing to the warming trend. If so, it is interesting to weigh these facts alongside those reported by William Booth in your newspaper July 16: according to researchers at the Georgia Institute of Technology, the primary cause of "whopping" temperature increases in Atlanta since the mid-'70s is the loss of 20 percent of the city's trees. Planting more trees in urban areas would tend to lower urban temperatures and thus lower related air pollution.

Urban forestry is the heart of President Bush's campaign to plant and improve 1 billion new trees every year for the next 10 years. Moreover, an appreciation for the invaluable functions of trees is also at the heart of the president's recent call for a global forestry convention to be completed by 1992. President Bush knows that trees are both symbols and soldiers in our campaign to protect the environment.

-- Michael R. Deland The writer is chairman of the President's Council on Environmental Quality.