Kajian potensi, sebaran, dan penutupan vegetasi hutan rakyat di DAS Garang Hulu

RAHARJO, Prof.Dr.Ir. H. Djoko Marsono

2007 | Tesis | S2 Ilmu Kehutanan (Manaj. Konservasi Sumberdaya Al

Menurut Undang-Undang Nomor 41 tahun 1999 tentang Kehutanan, agar hutan berfungsi optimal secara ekologi, sosial dan ekonomi, maka luas hutan minimal 30% dari luas daratan dan tersebar secara merata. Upaya yang dilakukan untuk menambah fungsi hutan di Jawa Provinsi Jawa Tengah antara lain membangun hutan rakyat. Pada saat ini animo masyarakat Jawa Tengah menanam hutan rakyat sangat tinggi termasuk pada wilayah Sub DAS Garang Hulu. Wilayah ini mempunyai kelerengan, ketinggian dan jenis tanah yang bervariasi. Disamping itu, desa/kelurahan pada wilayah Sub DAS ini juga mempunyai variasi dalam hal kepadatan penduduk, mata pencaharian, dan rata-rata pemilikan lahan. Penelitian ini bertujuan untuk 1) mengkaji potensi dan sebaran vegetasi hutan rakyat, 2) mengkaji penutupan vegetasi hutan rakyat, dan 3) mengetahui hubungan antara penutupan vegetasi hutan rakyat dengan berbagai faktor lingkungan. Penelitian ini dilakukan dengan pengamatan pada unit lahan dan desa/kelurahan di lokasi penelitian. Unit lahan didasarkan hasil overlay peta kelerengan, ketinggian tempat dan jenis tanah. Hasil overlay ketiga peta tersebut terdapat 33 unit lahan. Jumlah desa/kelurahan pada wilayah ini sebanyak 37 desa/kelurahan. Berdasarkan peta hutan rakyat yang dioverlay dengan peta unit lahan tersebut, dapat dianalisis potensi, sebaran dan penutupan vegetasi hutan rakyat pada masing-masing unit lahan dan desa/kelurahan serta seluruh wilayah DAS. Kemudian berdasarkan penutupan vegetasi pada masing-masing unit lahan dan desa/kelurahan dapat dianalis pola hubungan antara penutupan vegetasi hutan rakyat dengan faktor lingkungan yang meliputi kelerengan, ketinggian tempat, jenis tanah, kepadatan penduduk, jumlah petani dan pemilikan lahan. Hasil penelitian menunjukkan bahwa potensi hutan rakyat di lokasi penelitian sebesar 2.028,599 ha yang tersebar pada 28 desa/kelurahan. Wilayah dengan potensi tinggi (> 100 ha) terdapat di enam desa/kelurahan atau sebesar 1.282,218 ha (68,14%), potensi sedang (> 50 – 100 ha) terdapat di empat desa dan potensi rendah (< 50 ha) terdapat di 17 desa/kelurahan. Penutupan vegetasi hutan rakyat secara keseluruhan di lokasi penelitian masih belum optimal atau sebesar 24,22% (kategori kecil) tetapi pada beberapa unit lahan atau desa/kelurahan penutupan vegetasi hutan rakyat sudah mencapai optimal, yaitu kategori cukup besar (30 – < 45%) terdapat pada satu unit lahan atau empat desa/kelurahan, kategori besar (45 – < 60%) terdapat pada tiga unit lahan atau dua desa/kelurahan dan kategori sangat besar (> 60%) terdapat di enam unit lahan atau empat desa/kelurahan. Pada wilayah Sub DAS Garang Hulu, tingkat penutupan vegetasi hutan rakyat optimal (> 30%) terdapat pada kelerengan >8 – 40%; ketinggian <1600 m dpl; jenis tanah latosol coklat tua kemerahan, latosol coklat dan andosol coklat; kepadatan penduduk >1000- 3000 jiwa/km2; jumlah petani >10 – 60% dari jumlah penduduk, rata-rata pemilikan lahan >0,100 – 0,400 ha/keluarga dan >0,600 – 0,700 ha/keluarga.

According to forestry law no. 41 year 1999 that forest can give optimal functions for ecology, social and economic if it has area at least 30% of the total continent area and spread over evenly. Some efforts are done to solve the problem, for example by developing people forest. At this moment, the Central Java community is very interested in planting the trees for people forest, including in Garang Hulu sub watershed. This area has slope, altitude, and soil slope which are very vary. Besides, the villages in this sub catchment also have variations of population density, occupation, and farm ownership. The aims of this study are 1) to study the potency and the distribution of people forest; 2) to study the vegetation cover of people forest, and 3) to understand the relationship between vegetation cover of people forest with environmental factors. This research was conducted by doing perception at farm unit and villages in the field. Farm units are based on the result of the overlay of slope map, altitude map, and soil type map. Result showed that there are 33 farm unit and 37 villages. From the people forest map overlaid with land use map, it can be analysed the potency, distribution and vegetation cover of people forest at each farm unit and at each village and in that sub catchment. Then, it can be analysed the pattern relation between vegetation cover of people forest with environmental factors: the land slope, altitude, soil type, population density, the number of farmers and the land ownership. Result showed that the potential of people forest are 2.028,599 Ha which are spread over 28 villages. There are six villages that have high potential of people forest (> 100 ha) or equal to 1.282,218 ha (68,14%), four villages have moderate potential of people forest (> 50-100 Ha), and seventeen villages have low potential (< 50 ha). The vegetation cover from private forest in the whole area study has not been optimal yet, it was only 24,22% (small category) but the vegetation covers from people forest at some farm units and villages have already reached optimal size, that are the optimum vegetation cover with medium size ( 30 - < 45%) was in one farm unit or four villages, large size ( 45 - < 60%) was in three farm unit or villages, and very large size (> 60%) was in six farm unit or four villages. There was a relationship between vegetation cover from private forest with environmental factors: slope, altitude, soil types, population density, number of farmers and the farm ownership in the villages. The optimum vegetation cover of people forest (> 30%) was on the land which has slope steepness > 8 - 40%; altitude < 1600 dpi m; soil types: latosol dark reddish brown, brown latosol, and brown andosol; population density > 1000- 3000 people / km2; number of farmers > 10 - 60% of whole residents, and the average of farm ownership > 0,100 - 0,400 ha / family and > 0,600 - 0,700 ha / family.

Kata Kunci : Hutan Rakyat,Vegetasi Hutan,Ekosistem DAS, potency, distribution, vegetation cover, people forest