LARGER proportion--15 percent--of Americans lived below the poverty line in 1982 than in any year since 1965. Why? The short answer, and the one predictably stressed by Reagan administration spokesmen, is that there is more poverty because of the extended recession, or recessions, of the past several years. That is true. But it doesn't follow that the economic recovery that seems to be occurring will assuage all the ills that afflict a nation when one in seven of its citizens lives in poverty.

Consider this: 22 percent of the nation's children lived in poverty in 1982. That is more than one out of five of the people who will, 40 years from now, be the prime wage-and salary-earners of this country. A fair number of these children are in families that move above and below the poverty line with some frequency. But more seem to be ending up below, and the flux means that more than 22 percent of today's children will be living in poverty during some significant portion of their childhood years. It is not immediately clear how policies of cutting taxes, education aid, food stamps, and school lunches will help these youngsters become productive citizens when they become adults.

President Reagan attracted some attention, the day the poverty figures were announced, by saying that he would set up a task force to study how to eliminate hunger. He might consider other task forces to study how his budget cuts have affected the chances of the 22 percent of children living in poverty.

Another fact to consider: fully 36 percent of families headed by women were under the poverty line in 1982. Increasingly, the difference between poverty and something like affluence for many Americans is the difference between a one-parent and a two-parent family. The continuing gap between black and white incomes results in large part from the increase in female-headed households among blacks. Two-adult black families now have median incomes which are 78 percent of those of their white counterparts--a sharp improvement over the last 20 years. No one knows how to stop the increase in one-parent families or to solve the economic and social problems associated with it. But who denies that these problems must be addressed?

It is worth noting that there is not much more poverty in the South (18 percent) than in the rest of the country (13 percent). And for the first time, the poverty level among the elderly is, at 14.6 percent, slightly below that of people below 65. Social Security and other benefits have evidently kept older people ahead of inflation. It would be nice if such automatic protection applied to the 22 percent of children who were under the poverty line in 1982, or if we could be confident that, as they grow up, they will be able to overcome the handicaps their economic situation today imposes.