Kemelimpahan tumbuhan penyusun komunitas hutan rawa sagu (Metroxylon sagu) di Halmahera Barat

BALATJAI, Soni, Dr. Tjut Sugandawaty Djohan, M.Sc

2009 | Tesis | S2 Biologi

Penelitian ini bertujuan mempelajari kemelimpahan tumbuhan penyusun komunitas hutan rawa sagu. Lokasi kajian terdapat di komunitas rawa sagu permanen dan temporal di Halmahera Barat. Berdasarkan tinggi muka air lokasi kajian dibagi kedalam tiga zona. Data vegetasi dikoleksi dari setiap zona dengan ukuran plot 20 m x 20 m. Demikian juga untuk sampel kimia tanah dan air, dikokleksi 0,5 m di dekat akar dan 1 m – 2 m dikoleksi jauh dari akar tumbuhan sagu, untuk mengukur parameter NO3, NH4, PO4, SO4, C organik, pH dan tektur tanah. Kemudian dipelajari profil hutan rawa sagu. Hasil penelitian menunjukan bahwa Growth form dominan untuk tumbuhan sagu adalah seedling sebanyak 1264 indivdiu/ha. Sedangkan seedling tumbuhan pendatang sebanyak 221 individu/ha. Sebaliknya berdasarkan Growth form untuk tingkat jenis, seedling yang dominan adalah Metroxylon longispinum sebanyak 892 individu/ha (21,60 %). Sedangkan tumbuhan pendatang adalah Artocarpus sp 196 individu/ha (6,28 %). Jenis sagu M .sylvester tidak hadir di komunitas rawa temporal. Sebaliknya pohon tumbuhan pendatang tidak hadir pada tinggi muka air 132 cm di rawa permanen. Ternyata kehadiran tumbuhan didikte oleh tinggi muka air dan respon terhadap kandungan hara dalam lapisan tanah aerobik. Profil hutan rawa sagu membentuk tiga strata. Profil tertinggi adalah pohon Ficus benjamina. Dengan kehadiran tumbuhan pendatang di rawa sagu, ekosistem rawa sagu dalam keterancaman.

This research was to study the abundance of plant community on sago swamp forest on permanent and temnporal swamp in Western Halmahera. Based on the water table we the studied area in three zone. In each zone, we collected vegetation data using quadrat plot of 20 m x 20 m with 6 replicates. Similary, soil and water chemistry samples were collected nex 0.5 m to basal, and 1 to 2 m of Sago plant. Parameter measure were NO3, NH4, SO4, PO4, C organic, pH, and soil textures. Forest profiles were also studied. There were 5 species of true sago, M. rumhii Martius, M. sagu Rottb, M. microcantum, M. longispinum, M. Sylvester, and 15 species of visitor plants. The growth-form dominant was seedling of sago, 1264 individual pe ha. The seedling dominance was M. longispinum, 892 indiv. per ha (21,60%). The M.sylvester was not present in the temporal sago swamp. The visitor plant dominance was Arthocarpus sp., 196 individual per ha (6,28%). In permanent sago swamp with 132 cm depth, the plant of visitor was not found. The soil layer in the swamp was aerobic and was response by the available soil nutrient. Thus water level and the nutrients determined the distribution of sago plants and tree visitor plants. The forest sago swamp profiles were composed by three layers which was dominanted by the highest visitor tree, Ficus benjamina. Therefore the visitor plants are Threatened the sago swamp.

Kata Kunci : Sagu,Tumbuhan pendatang,Tinggi muka air,Tekstur tanah,Nutrien,Sago, visitor plant, water level, soil texture, nutrient