Pengaruh faktor sosial ekonomi masyarakat terhadap kelestarian fungsi hutan lindung (studi kasus di kawasan hutan lindung gunung Sindoro kecamatan Bansari kabupaten temanggung) = Effects of community's social and economic variables on the preservation of protected forests (a case study in gunung Sindoro protected forests, Bansari district, Temanggung regency)