THE FIRST "state of the parks" report published recently by the National Park Service provided a remarkable overview of what environmental problems really are. The parks are in trouble -- aren't they always? -- and the problems range from such well-advertised ones as too many visitors to more subtle ones, like acid rain and neighborhood decay. But in between are environmental problems of the kind almost no one talks about.

In Haleakala National Park, for instance, "highly aggressive animals and plants," including mongooses and marijuana, are threatening such fragile showpieces as the silverswood. In Maryland's Catoctin Mountain National Park, "a considerable wildlife migration" caused by development outside the park is troubling the rangers. On the Channel Islands in California wildlife is under threat from offshore drilling, anchovy fishing and -- yet -- shock waves from launches of space vehicles. At the Petrified Forest in Arizona, the problem is the theft, "in small chips," of as much as 12 tons of wood-turned-to-rock each year.

The thrust of the report is that many of most serious threats to parks come from forces their custodians cannot control. The subdivisions creeping up on the battlefields at Fredericksburg and Spotsylvania, the acid rain that is killing the trout in the Great Smoky Mountains and the air pollution that threatens some of the great western parks cannot be controlled by the Park Service. But their impact on these national treasures is just as threatening as the internal problems -- overcrowding, shore erosion, vandalism and an excess (or a shortage) of wildlife. The Park Service and its new director, Russell E. Dickerson, have their hands full trying to keep the parks the pleasant places they are now. So do the rest of us.