BOWLING GREEN, OHIO — A researcher claims the US government has been unfairly blamed for hardships faced by Spanish Americans in the upper region of the Rio Grande Valley and that some of the problems are based on culture and tradition. Alvar Carlson, chairman of the geography department at Bowling Green State University, is author of ``The Spanish-American Homeland: Four Centuries in New Mexico's Rio Arriba.'' Since the signing of the 1848 Treaty of Guadalupe Hidalgo by the United States and Mexico, many historians, anthropologists, and sociologists, as well as Spanish Americans, have accused the US of implementing unfair land policies. The treaty ensured landowners of their continued property rights following the Mexican War if they were found to be legitimate under Spanish and Mexican laws. The American legal system was left the task of determining the validity of land claims, particularly grants that included vague boundaries. Rio Arriba, located mostly between Taos and Albuquerque, is populated largely by Spanish Americans; the region has been beset by rural poverty, a semi-arid climate, and cultural conflicts with its Spanish, Indian, and Anglo neighbors. After examining patterns of settlement, economic development, demographics and material culture, Mr. Carlson writes that the US accommodated Spanish-American homesteading, allowed extensive use of previously claimed grant lands after they were incorporated into the public domain, and sanctioned Spanish-American encroachment on Pueblo Indian land grants. Carlson said Spanish Americans have been trapped in a subsistence economy because of land use patterns, inheritance customs, folk culture, and the limited possibilities for agriculture and outmigration. -PATHNAME- /usr/local/etc/httpd/plweb/DBGROUPS/paper/database/tape/91/mar/week10/afil25a.