KAPASITAS INFILTRASI DI TEGAKAN Eucalyptus pellita dan Hibrid acacia KHDTK ALAS KETHU KABUPATEN WONOGIRI JAWA TENGAH

YUAN SASMITA NUGRAHA, Prasetyo Nugroho, S.Hut., M.Sc.,

2014 | Tugas Akhir | D3 KEHUTANAN

Pengelolaan hutan sebagai upaya untuk pemulihan kondisi hutan merupakan tindakan yang sangat diperlukan. Dengan adanya pengelolaan hutan, akan mempengaruhi keseimbangan lingkungan kawasan salah satunya dari aspek keseimbangan hidrologis atau tata air. Pada hakekatnya hutan berfungsi untuk memberikan perlindungan terhadap lingkungan dari degradasi lahan serta meningkatkan besarnya kapasitas infiltrasi pada tanah. Karena letak Alas Kethu berada di hulu DAS Bengawan Solo, Alas Kethu mempunyai peran penting dalam pengendalian daur air. Tujuan dari penelitian ini adalah untuk mengetahui besarnya kapasitas infiltrasi pada areal KHDTK Alas Kethu. Penelitian ini dilaksanakan di Kawasan Hutan Dengan Tujuan Khusus, Hutan Penelitian Alas Kethu, yang terletak di Dusun Seneng, Desa Giriwono Kecamatan Wonogiri, Kabupaten Wonogiri, Jawa Tengah. Penelitian dilakukan menggunakan metode double ring infiltrometer, dengan pengukuran penurunan air agar mencapai konstan. Penentuan plot pengambilan data dilakukan secara purposive sampling dengan penentuan plot berdasarkan kriteria tingkat kerapatan dan berat seresah yaitu: jarang, sedang, dan rapat. Penelitian dilaksanakan pada tegakan Eucalyptus pellita dan tegakan Hibrid acacia yang ditanam pada tahun tanam yang sama yaitu bulan Januari tahun 2011. Hasil kapasitas infiltrasi yang didapat untuk plot 1 sebesar 54 cm/jam; plot 2 sebesar 60 cm/jam; plot 3 sebesar 54 cm/jam; plot 4 sebesar 24 cm/jam; plot 5 sebesar 30 cm/jam; plot 6 sebesar 30 cm/jam; plot 7 sebesar 12 cm/jam; plot 8 sebesar 12 cm/jam; plot 9 sebesar 18 cm/jam; plot 10 sebesar 24 cm/jam; plot 11 sebesar 24 cm/jam; plot 12 sebesar 36 cm/jam; plot 13 sebesar 12 cm/jam; plot 14 sebesar 18 cm/jam; plot 15 sebesar 18 cm/jam; plot 16 sebesar 12 cm/jam; plot 17 sebesar 12 cm/jam; dan plot 18 sebesar 12 cm/jam. Untuk rata-rata hasil kapasitas infiltrasi sebesar 25,67 cm/jam dengan hasil kapasitas infiltrasi terbesar pada plot 2 dengan jenis tegakan Eucalyptus pellita dengan kerapatan seresah rapat, dan hasil kapasitas infiltrasi terendah pada plot nomor 18 dengan jenis tegakan Hibrid acacia dengan kerapatan seresah jarang. Pada pengambilan data kapasitas infiltrasi ini faktor penutupan lahan lebih dominan dalam mempengaruhi nilai kapasitas infiltrasi.

Forest management as an effort to restore the condition of forests is an indispensable action. With forest management, it will affects the balance of the environment. One of the aspects is the hydrological balance or the water management. Naturally, forests serve to provide protection for the environment from land degradation and increase the magnitude of infiltration capacity of the soil. Forest with Special Purpose Alat Kethu is located at the upper course of Bengawan Solo watershed. Since it is located at the upper catchment of Bengawan Solo watershed, Alas Kethu has an important role in controlling the water cycle. The purpose of this research is to know the magnitude of infiltration capacity in the area of Forest with Special Purpose Alas Kethu. This research was carried out in the forest area with a special purpose, the Research Forest of Alas Kethu, which is located in Dusun Seneng, Desa Giriwono, Kecamatan Wonogiri, Kabupaten Wonogiri, Central Java. The research was carried out using the method of double ring infiltrometer, with the measurement of water decreasing in order to achieve a constant state. Determining the plot of data collection was done by purposive sampling based on the criterion of density level and weight of the litter: rare, medium, and dense. The research was carried out on the stands of Eucalyptus pellita and Hybrid acacia that were planted in the same planting year, which was in January 2011. The result of infiltration capacity were plot 1 was 54 cm/jam; plot 2 was 60 cm/jam; plot 3 was 54 cm/jam; plot 4 was 24 cm/jam; plot 5 was 30 cm/jam; plot 6 was 30 cm/jam; plot 7 was 12 cm/jam; plot 8 was 12 cm/jam; plot 9 was 18 cm/jam; plot 10 was 24 cm/jam; plot 11 was 24 cm/jam; plot 12 was 36 cm/jam; plot 13 was 12 cm/jam; plot 14 was 18 cm/jam; plot 15 was 18 cm/jam; plot 16 was 12 cm/jam; plot 17 was 12 cm/jam; and plot 18 was 12 cm/jam. The obtained results were the average of infiltration capacity on 18 plots which was 25,67 cm/hour with the lowest infiltration capacity was 12 cm/hour, and the highest was on plot 2 with 60 cm/hour. On the data collection of this infiltration capacity, the factor of land cover was dominant in affecting the values of infiltration capacity.

Kata Kunci : pengelolaan hutan, penutupan lahan, dan kapasitas infiltrasi