Karakteristik Tanah Tegakan Shorea leprosula Miq. dan Shorea selanica (Lam.) Blume pada Dua Teknik Penanaman di Hutan Penelitian Gunung Dahu, Bogor
Abstract
Konversi hutan menjadi lahan pertanian, pemukiman, perkebunan, serta perambahan dan pembalakan liar dapat memicu terjadinya degradasi lahan yang dapat memperburuk kondisi lingkungan. Revegetasi menggunakan jenis asli bernilai ekonomi tinggi merupakan salah satu cara yang dapat ditempuh untuk memperbaiki keadaan tersebut. Hutan Penelitian Gunung Dahu (HPGD) telah melakukan revegetasi menggunakan jenis Shorea leprosula dan Shorea selanica dengan menerapkan teknik penanaman line planting dan total planting. Kegiatan revegetasi akan berpengaruh pada perbaikan sifat-sifat tanah yang kemudian mempengaruhi tingkat kesuburan tanah. Kondisi tanah berupa perpaduan sifat fisik, kimia dan biologi tanah serta ketepatan perlakuan silvikultur yang diberikan menjadi faktor penentu keberhasilan revegetasi.
Penelitian ini bertujuan mengkaji pertumbuhan dan sifat tanah tegakan S. leprosula dan S. selanica dengan teknik penanaman berbeda di HPGD melalui analisis sifat fisik, kimia dan biologi tanah (meso dan makro fauna) serta memperkirakan kesuburan tanah menggunakan Soil Fertility Index (SFI) dan Soil Evaluation Factor (SEF). Analisis pertumbuhan dilakukan dengan mengukur tinggi dan diameter pohon. Pertumbuhan kedua jenis Shorea dipengaruhi oleh cahaya sehingga dilakukan pengukuran Leaf Area Index (LAI) dengan teknik hemispherical canopy photograph. Pengukuran biomassa serasah dilakukan untuk mengetahui besarnya masukan bahan organik dari tanaman untuk kesuburan tanah dan purposive sampling merupakan metode yang dipilih untuk pengambilan sampel tanah. Adapun pengamatan biologi tanah dilakukan dengan metode hand sorting dan corong Berlese. Sebagai pembanding, pengamatan juga dilakukan pada lahan yang belum direvegetasi dan hutan alam terdekat.
Hasil penelitian menunjukkan bahwa perbedaan teknik penanaman memberikan pengaruh nyata terhadap pertumbuhan diameter S. leprosla dan S. selanica. Pertumbuhan diameter terbaik terdapat pada jenis S. selanica dengan teknik penanaman line planting sebesar 29.96 cm dan riap rata-rata MAI 1.25 cm/tahun namun tidak berpengaruh terhadap tinggi. Nilai LAI tertinggi terdapat pada petak line planting dengan jenis S. selanica sedangkan biomassa serasah terbesar terdapat pada petak jenis S. leprosula teknik line planting yang diikuti dengan tingginya nilai karbon serasah mencapai 14.53 ton/ha. Hasil analisis tanah menunjukkan tidak terdapat perbedaan yang mencolok antar teknik penanaman dan 24 tahun pasca penanaman, kondisi tanah jauh lebih baik dibanding lokasi yang belum direvegetasi. Status keanekaragaman fauna tanah di HPGD tergolong sedang hingga tinggi dengan ditemukannya 42 jenis dari 26 famili. Petak S. leprosula line planting memiliki nilai SFI dan SEF tertinggi setelah hutan alam. SFI dan SEF dapat diterapkan di HPGD berdasarkan uji korelasi yang menunjukkan skor PC1 berkorelasi positif dan sangat kuat dengan SFI dan SEF. Forest conversion into agricultural fields, residences, farms, and illegal encroachment and logging can trigger land degradation, damaging environmental conditions. Revegetation using original type and high economic value is a method to resolve this situation. Revegetation using Shorea leprosula and Shorea selanica has been conducted in Gunung Dahu Research Forest (GDRF) by implementing line planting and total planting techniques. Revegetation will affect the improvement of soil properties, which will improve soil fertility. Soil condition is a mixture of the soil’s physical, chemical, and biological properties. Therefore, the correctness of silviculture treatment will be a determining factor for revegetation success.
This research aimed to study the growth and soil properties of standing crops of S. leprosula and S. selanica using different planting techniques in GDRF through physical, chemical, and biological analysis on the soil properties (meso- and macrofauna). The research was also conducted to estimate the soil fertility using Soil Fertility Index (SFI) and Soil Evaluation Factor (SEF). Growth analysis was conducted by measuring the height and the diameter of the tree. The second growth for Shorea was affected by lights, hence Leaf Area Index (LAI) analysis using the hemispherical canopy photograph technique was undertaken. Brown waste biomass measurement was conducted to know the amount of organic material input from plants for soil fertility, and purposive sampling was the selected method to take the soil samples. Soil biological observation was conducted using hand sorting and the Berlese funnel. As a comparison, observation was also done on not revegetated fields and the nearest natural forest.
The research results indicated that the difference in planting techniques significantly affected the diameter growth of S. leprosla and S. selanica. The best diameter growth was found on S. selanica with line planting technique at 29.96 cm and MIA at 1.25 cm/year. However, it did not affect the height. The highest LAI was found on line planting crop with S. selanica. In contrast, the enormous brown waste biomass was found on S. leprosula with the line planting technique, which was followed by the massive number of brown waste biomass at 14.53 ton/ha. The soil analysis results showed that there was no significant difference between planting techniques and 24-years post-planting. The soil condition was way better than the non-revegetated location. The fauna diversity status in GDRF soil was categorized into moderate to high, with 42 types from 26 families being found. S. leprosula line planting crop had the highest SFI and SEF after the natural forest. The SFI and SEF can be applied in GDRF based on the correlation test which showed that the PC1 score positively correlated with both SFI and SEF.
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- MT - Forestry [1411]