UN watch on environment gets lonelier

The United Nations is trying to revive the world's flagging interest in preserving its environment.

This spring it will hold an international conference here in Nairobi to try to rekindle the spirit of conservation lighted in Stockholm nearly 10 years ago. The Stockholm UN Environment Conference, attended by 116 nations, resulted in the founding of the United Nations Environment Program (UNEP), an organization that seeks to ''safeguard and enhance the environment for present and future generations.''

However, today's preoccupation with failing economies, shortages, and inflation has diverted international attention from those earlier conservation ideals.

The slackening of interest in environmental preservation is felt here in reduced contributions to UNEP, which in turn have forced UNEP to pare back conservation programs.

Many prominent early supporters, including the United States and several key Western nations, have indicated they will contribute less to UNEP. Sweden and a few others are coming forward with increased support.

''The economic recession has applied the brake,'' says Mustapha Tolba, the Egyptian scientist who is UNEP's executive director.

''There are no firm indications that the traditional, generous support of principal donors to the environment fund will be maintained,'' he adds. ''On balance the indications are that there will be a substantial deficit on . . . contributions set for the next two years of $120 million.''

The UNEP believes the conference next May will have a crucial bearing on the future of the environment cause.

Conference members will be forced to evaluate the need for conservation, Dr. Tolba says. They will have to decide whether UNEP programs will be advanced or set further back. He says they will have to consciously decide whether to run the programs down, and whether they will be abrogating international responsibilities.

UNEP often found environmental concerns often split along lines dividing the industrialized and developing nations. Industrialized countries were interested mainly in pollution, air and water contamination, and discharging toxic and dangerous wastes into water. They were also interested in human quality of life and the effect on nature's laws of man's encroachment into the wilderness.

In the developing world the issues were often those relating to human survival: erosion of forest and grass cover, soil erosion, and the advance of the desert, as well as population growth and exhaustion of resources needed for food, water, fuel, and shelter.

The UNEP, based in Nairobi, tries to provide advice and technological know-how to nations to study and tackle their environmental problems. Its scientists, chemists, biochemists, desert experts, plant pathologists, and economists help those who seek their advice; they do not themselves undertake field projects. However, the organization coordinates an ''earthwatch'' operation, makes a scientific assessment of the ''state of the world environment ,'' and promotes environmental management.

UNEP, unlike many UN and other international agencies, exists almost entirely on voluntary contributions. Its governing council of 58 nations meets once a year to set a budget and program priorities.