Mangrove merupakan komunitas vegetasi pantai tropis dan sub tropis yang didominasi oleh beberapa jenis pohon mangrove. Kerapatan mangrove sangat dipengaruhi oleh jenis substrat. Tujuan penelitian adalah untuk mengetahui hubungan antara jenis substrat terhadap kerapatan pohon Rhizophora sp di hutan mangrove Kota Tarakan dengan membandingkan jenis substrat terhadap kerapatan spesies tersebut. Penelitian ini dilakukan pada bulan Maret sampai dengan Mei 2019, metode yang digunakan dalam penelitian ini metode deskriptif kuantitatif. Pengambilan sampel dilakukan di 3 stasiun, yaitu daerah Kawasan Konservasi Mangrove dan Bekantan (KKMB) dan Kawasan Konservasi Mangrove Mamburungan, Kota Tarakan, Provinsi Kalimantan Utara. Hasil penelitian terdapat 3 jenis substrat yaitu lempung liat berdebu, lempung berdebu dan liat berdebu. Terdapat 3 jenis vegetasi Rhizophora sp, yaitu Rhizophora Apiculata, Rhizophora Mucronata dan Rhizophora Stylosa.
Kata Kunci: Kerapatan, Kota Tarakan, Mangrove, Substrat

Mangroves are tropical and sub-tropical coastal vegetation communities dominated by several types of mangrove trees. Mangrove density is strongly influenced by the type of substrate. The research objective was to determine the relationship between the type of substrate and the density of Rhizophora sp trees in the mangrove forests of Tarakan City by comparing the type of substrate to the density of these species. This research was conducted from March to May 2019, the method used in this research is quantitative descriptive method. Sampling was carried out at 3 stations, namely the Mangrove and Proboscis Monkey Conservation Area (KKMB) and the Mamburungan Mangrove Conservation Area, Tarakan City, North Kalimantan Province. The results of the study were 3 types of substrates, namely dusty clay, dusty loam and dusty clay. There are 3 types of vegetation Rhizophora sp, namely Rhizophora Apiculata, Rhizophora Mucronata and Rhizophora Stylosa. Keywords: Density, Tarakan City, Mangrove, Substrate