Economic recession and a perceived shift in U.S. policy on the part of the Reagan administration marked the second conference of the U.N. Environment Program, which ended today with a call for renewed awareness of the long-term effects of environmental deterioration.

In contrast to the colorful and spirited conference on the human environment 10 years ago in Stockholm, which created the UNEP, the special session that ended today was marked by "more light than heat," according to the program's deputy executive director, Peter Thacher.

"Today, the link between the economy and the environment is not the argument it was 10 years ago when the developing countries perceived it as a plot to stall their economic development," Thacher added.

The week-long meeting, which had been called to assess the Environment Program's first decade and future goals for global environmental protection was dogged by divisions along North-South lines.

Of primary concern to many of the delegates and observers from the 105 nations attending was what has been interpreted as the U.S. retreat, under the Reagan administration, from its former leadership role on environmental issues. One target for criticism has been the slashed U.S. contribution to the program, a result of the global economic recession and--it is felt here--changed policy on environmental matters.

The budget target for the current 1982-83 program has been receding further as funding has become critical. A two-year budget of $120.5 million was approved at the ninth session of the program's governing council. With the 10th governing council scheduled to start Thursday, officials are now settling for a maximum of $60 million.

This will cut by about half the program's data collection programs on such natural resources as forests, soil and water and atmospheric pollutants such as acid rain.

The United States traditionally has been the bulwark of the Environment Program's activity through its financial support, and from 1978 to 1981 donated about $10 million annually. Washington then withdrew this support when the Reagan administration sought to rationalize its aid program on a return-on-investment basis, meaning benefit to U.S. security interests.

The administration's current contribution of $7.85 million is threatened with further cuts to $3 million next year.

James L. Buckley, under secretary of state for security assistance, science and technology and one of three U.S. delegation heads here, said, "We feel that the financial burden ought to be borne more broadly. We feel that's healthier for the world community."

Buckley also disagreed with the notion voiced here of flagging U.S. leadership. "I'm not sure there's any basis for these observations," he said. "We have had discussions with various delegations and in a number of instances we've changed their minds. That's what leadership is all about."

The Reagan administration's hard-line stance in the end won the consensus of most of the industrialized nations, with exceptions such as Canada, the Netherlands, Japan and Sweden, on most issues, leaving the developing countries' demands in the cold.

African nations, against a background of shrinking forests, soil erosion and polluted water, called unsuccessfully for more money to protect their valuable natural resources and a shift of the Environment Program's role from that of catalyst to project manager.

The official U.S. position on this, in which it is backed by Britain, West Germany, France and some Environment Program officials, was that environmental development should be supported by the private sector.

Thacher cited the cases of Nigeria and the Ivory Coast, where tropical forests may disappear by the turn of the century. According to Thacher, forestry-related industries should promote responsible behavior toward forest protection in countries where the forest cover is threatened.

The idea for an environmental commission run along the lines of the Brandt Commission, which called in 1980 for a more equitable distribution of global wealth, was raised at the conference by Japan. The proposal, which calls for a panel of statesmen and scientists to set environmental priorities for the next century, has been referred to the program's governing council.