Survivorship and Growth Rate of Rasamala (Altingia excelsa Noronha), Puspa (Schima wallichii (DC.) Korth.) and Jamuju (Dacrycarpus imbricatus (Blume) de Laub.) on Degraded Land in the Upstream of Cisadane Watershed

Abstract

Changes in land use often threaten biodiversity. A slow primary succession can, however, be accelerated by conducting a restoration program. The aims of this study were to i) obtain data of survivorship and growth rate and ii) assess the influences of environmental factors on the growth of Rasamala (Altingia excelsa), Puspa (Schima wallichii), and Jamuju (Dacrycarpus imbricatus) on a degraded land in the upstream of Cisadane watershed. Observations were carried out two times: 6 and 12 months after planting. Survivorship percentages at different slopes were obtained by dividing the amount of living species during the period of the observation with the total amount of plants planted at the beginning of the observation. A PCA biplot analysis was used to assess the interaction between biotic and abiotic factors influencing the survivorship. Growth rate was done by measuring the height, diameter, and canopy spread of individual plants. Assessments of biotic and abiotic environment that influence the growth rates were also conducted. The results showed that the survivorship percentages of Rasamala, Puspa, and Jamuju were 87,18%, 82,05%, and 77,14%, respectively. On the 40° slopes, the survivorship of Rasamala was 93,75%, while those of Puspa and Jamuju were 84,61% and 66,67% respectively. On the 60% slopes, the survivorship was 82,25% for Rasamala, 81,81% and 64,70% for Puspa and Jamuju respectively. Higher growth rate was found in Jamuju, followed by Puspa and Rasamala. Environmental factors (both biotic and abiotic) significantly influenced the three species survivorship. Plant height, diameter and canopy area had significant correlations with plant growth rates.

Bencana alam seperti tanah longsor dan banjir makin sering terjadi di Indonesia. Salah satu penyebabnya adalah peningkatan laju deforestasi dari 2,3% menjadi 4,5% per tahun selama periode tahun 1999-2000. Peningkatan laju deforestasi tersebut mengakibatkan luas lahan terdegradasi di Jawa Barat meningkat hingga mencapai 33,6%. Berdasarkan pertimbangan di atas perlu dilakukan restorasi ekologi dengan menggunakan spesies asli sebagai bagian dari upaya pemulihan ekosistem (habitat). Indikator keberhasilan restorasi bisa diukur melalui suatu penelitian tentang daya sintas tumbuhan yang ditanam. Rasamala (Altingia excelsa), Puspa (Schima wallichii) dan Jamuju (Dacrycarpus imbricatus) merupakan spesies-spesies asli yang mempunyai nilai konsevasi dan juga ekonomi. Penelitian ini bertujuan untuk menentukan spesies dengan daya hidup dan laju pertumbuhan terbaik pada ketiga spesies yang diamati, serta menentukan karakteristik lingkungan yang mempengaruhi daya sintas dan laju pertumbuhan dari ke tiga spesies tersebut.