<![CDATA[Penelitian ini dilakukan di kawasan rehabilitasi mangrove Pantai Utara Pemalang dan Rembang, Dari dua lokasi tersebut masing-masing di pilih tanam mangrove yang sama. Setiap tahun tanam dibagi dalam tiga zona dari arah laut ke darat. Kondisi ekosistem mangrove dikaji melalui pendekatan terhadap pengukuran kerapatan, rata-rata tinggi dan diameter, ketebalan lumpur, salinitas dan kandungan bahan organik pada setiap zonasi dan setiap tahun tanam. Untuk memperkirakan kandungan ekstrak tanin, pada setiap tahun tanam diambil 3 sampel vegetasi (dalam satu zona diambil satu sampel), kemudian dikelupas kulitnya, ditimbang dan dilakukan analisis laboratorium. Kandungan ekstrak tanin dalam satu tahun tanam dapat diestimasi dengan cara menghubungkan dengan nilai kerapatannya. Uji varian untuk dua sifat yang berbeda, dilakukan untuk melihat signifikasi kerapatan tanaman pada setiap tahun tanam pada dua lokasi rehabillitasi mangrove. Hasil penelitian menunjukkan bahwa estimasi kandungan ekstrak tanin di Pemalang dan Rembang pada tahun tanam 2002 rata-rata menunjukkan angka yang lebih tinggi daripada tahun tanam 2003 dan 2006. Pada tahun 2002 di Pemalang, estimasi ekstrak tanin sebesar 105,93 kg/ha sedangkan di Rembang mencapai 159,23 kg/ha. Pada tahun tanam 2006 mangrove di Pemalang mempunyai kandungan ekstrak tanin sekitar 80,90 kg/ha, sedangkan di Rembang sekitar 143,36 kg/ha.Kata kunci: Mangrove, ekosistem, ekstrak tanin. A Study of Rehabillitated Mangrove Ecosystem in Different Planting Year to Estimate Tannin Extract Content in Northern Coast of Central JavaAnstractThe research was conducted in the mangrove plantation areas of Pemalang and Rembang North coasts. From those two areas, mangrove vegetations with the same three plantation ages were chosen which were then divided into three zones from the sea. Tree density, height and diameter, the depth of sediment, water salinity and the content of organic matter were measured and assessed for each mangrove zones and plantation ages. In order to estimate the content of tannin extract of a mangrove tree, three mangrove trees of each plantation age were taken as samples. The wood of the trees were then peeled off, measured the weight and taken to the laboratory to analyze their tannin extract content. The content of tannin extract of the whole mangrove areas was obtained by multiplying the average of tannin extract content per tree with the vegetation density of those two mangrove areas. Varians analysis was employed to find out the significant different of the density three plantation ages of two mangrove rehabilitation areas. The results showed that for plantation years of 2002, the tannin extract content at both mangrove plantation areas of Pemalang and Rembang in averages was estimated to have a higher amount than those of plantation year 2003 and 2006. Respectively, the tannin extract content of plantation year of 2002 in Pemalang and Rembang were estimated to have 105.93 kg/ha and 159.23 kg/ha tannin extract. Mangrove vegetation with plantation year of 2006 in Pemalang contained 80.90 kg/ha, while for Rembang is 146.36 kg/ha.]]>
