HIGH in the Swiss Alps, the scenery is overwhelming: jagged peaks at eye level, an aqua-blue lake in a valley far below, and cows jangling their bells in summertime grazing.A tourist might never notice that fewer alpine flowers are blooming, or that the tops of some trees look sparse. The mist seen hanging in the valleys might be solely attributed to natural haze, instead of partially to pollution. But when you look closely, say Swiss environmentalists, the alpine ecology is not what it should be. If traffic, tourism, and industry continue at their present rate of development, the result will be increased danger of erosion, landslides, and avalanches, as well as a more marked change in alpine flora and fauna. This summer, the Swiss have taken action. In the warm months, Switzerland is a drive-through country for northern Europeans heading to points south. To help control ozone pollution, the Swiss have just reduced the highway speed limit to 120 km (75 miles) per hour for cars and 100 km (63 miles) per hour for trucks. They are strongly resisting pressure from the European Community to raise the allowed tonnage of trucks from 30 tons to 40 tons. Switzerland, not a member of the Community, is an important tran sit route for EC freight. Polluted air from traffic and industry is a major cause of damage to trees which hold soil and snow in place on steep slopes. According to a report published this year by the Research Institute for Leisure and Tourism at the University of Bern, the percentage of trees damaged nationwide has increased dramatically since 1985. In the high Alps, 72 percent of the trees are damaged, according to the institute; 57 percent in the lower Alps. The ecological challenges facing alpine countries cross international borders, says Werner Btzing, author of the book "Die Alpen," (the Alps) just published in May. He is encouraged by the first European conference on the Alps, which will involve the environmental Ministers of the seven Alpine countries and will take place this November in Austria. Whether the Swiss can act in a decisive, united way at the conference, however, is uncertain. Switzerland has a weak central government and much of environmental policy is directed locally, varying from area to area. The charming village of Gsteig, a stone's throw from the chic resort of Gstaad, for example, refuses to bow to development and allows no selling or building of houses or apartments for non-residents. Here atop Mt. Rigi, construction of moderate-sized resorts is allowed, but the area is a completely car-free, and can be reached only by cog rail or cable car. It contrasts starkly with the ski resort of Montana, a small city of concrete hotels high in the Alps. The Swiss construction industry is extremely influential and has shown it can block environmental initiatives. Hotel capacity has remained relatively stable over the last two decades, but the building of vacation homes has taken off, and land values have increased. While no new ski resorts have been built during the last five years, projects to enlarge resorts or to link them are in full swing, says Hansruedi Muller, director of the Research Institute for Leisure and Tourism. The weight of packed snow and heavy use of unofficial trails through woods damages plant life underneath, he says. Meanwhile, the use of snow-making equipment is being hotly debated because of its energy intensive nature and need for massive quantities of water - sometimes pumped from rivers into man-made reservoirs in the mountains. The Swiss have definitely become more conscious of the need to protect the Alps, says Mr. Muller, though he is not shy about putting the issue in perspective. "The Alps will outlive us," he says. "It's a question of whether the situation is getting worse for tourism and the inhabitants." A century ago, the Swiss were happy to have three warm winters in a row. Now, Muller says, consecutive winters without snow mean economic disaster.