Performance of Biophysical Mangrove Ecosystems in Birem Bayeun and Rantau Selamat Sub-District, East Aceh KERAGAAN BIOFISIK EKOSISTEM MANGROVE DI KECAMATAN BIREM BAYEUN DAN KECAMATAN RANTAU SELAMAT, ACEH TIMUR (Departemen Silvikultur, Fakultas Kehutanan dan Lingkungan, Institut Pertanian Bogor (IPB), 2015)