Studi Perakaran Berbagai Jenis Pohon Untuk Mempertahankan Stabilitas Tebing

Sausan, Tsarwah As (2019) Studi Perakaran Berbagai Jenis Pohon Untuk Mempertahankan Stabilitas Tebing. Sarjana thesis, Universitas Brawijaya.

Abstract

Menanam berbagai jenis pohon di lereng yang terjal merupakan cara mekanis dan hidrologis yang dapat mengurangi resiko terjadinya longsor. Secara mekanis akar dapat menpertahankan stabilitas lereng melalui dua mekanisme: mencengkeram tanah lapisan atas (0-5 cm) dan menopang tegaknya pohon dari gaya dorong massa tanah kearah bawah lereng (jangkar hidup). Fungsi akar pohon dipengaruhi oleh beberapa faktor: kualitas dan distribusi akar serta kekuatan geser tanah. Tujuan penelitian: (1) mengevaluasi nilai Indeks Cengkeram Akar (ICA) dan Indeks Jangkar Akar (IJA) beberapa pohon yang tumbuh di tempat-tempat berlereng di wilayah UB Forest dan (2) mempelajari sebaran akar berbagai jenis pohon yang tumbuh di tempat-tempat berlereng di wilayah UB Forest. Survei sistem perakaran pohon dilakukan di UB Forest (Malang) dengan kelerengan 26-28o (sangat terjal) pada bulan April-Juli 2019. Pengukuran dilakukan pada 9 jenis pohon berumur sekitar 4-10 tahun yaitu kopi robusta (Coffea canephora), kopi arabika (Coffea arabica), lamtoro (Leucaena leucocephala), dadap (Erythrina subumbrans), gamal (Gliricidia sepium), alpukat (Persea americana), petai (Parkia speciosa), waru (Hibiscus tiliaceus), dan suren (Toona ciliata) yang umum dijumpai disepanjang jalur survei, pengukuran setiap jenis pohon diulang 10x. Parameter yang diukur adalah Indeks Jangkar Akar (IJA) yaitu nisbah luas penampang akar vertikal dan batang, dimana akar vertikal dengan sudut >45o dari bidang horizontal; dan Indeks Cengkeram Akar (ICA) adalah nisbah luas penampang akar horisontal (sudut <45o) dan diameter batang. Pengambilan contoh akar untuk pengukuran Lrv (total panjang akar) dan Drv (berat akar) menggunakan metode root trenching dan pengukuran Drv dilakukan menggunakan metode intersepsi garis. Pohon dengan nilai ICA tertinggi (>1,50) ditunjukkan oleh kopi arabika (Coffea arabica), lamtoro (Leucaena leucocephala) dan alpukat (Parsea americana), sedangkan pohon yang memiliki nilai IJA tinggi (>3,00) adalah lamtoro (Leucaena leucocephala) dan kopi arabika (Coffea arabica). Nilai Lrv, Drv dan Specrol (Lrv/Drv) semakin menurun dengan meningkatnya nilai kedalaman tanah. Pada lapisan 0 – 20 cm, rata-rata nilai Lrv tertinggi terdapat pada pohon kopi arabika sebesar 0,0941 cm cm-3. Penanaman kombinasi berbagai jenis pohon berperakaran dalam dan rerumputan atau semak yang memiliki akar halus dan rapat akan meningkatkan potensi pohon menjaga stabilitas tebing.

English Abstract

Plant various types of tress on steep slope is a mechanical and hydrological way to reduce landslides. Mechanically, the roots can maintain slope through two mechanisms: holding the topsoil (0-5 cm) and support the upright of tree from the driving force due to soil mass movement (root anchoring). Tree root function is influenced by several factors: root quality, root distribution, and soil shear strength. This study aims to (1) evaluate the value of Index of Root Binding (IRB) and Index of Root Anchoring (IRA) of several trees that grow in sloped areas in UB Forest and (2) study the root distribution of various types of trees that grow in sloped areas in UB Forest. The survey of tree root system was conducted at UB Forest (Malang) with a slope range 26-28o (very steep) in April - Juli 2019. Measurement was made on 9 trees species of trees aged around 4-10 years, such as robusta coffee (Coffea canephora), arabica coffee (Coffea arabica), lamtoro (Leucaena leucocephala), dadap (Erythrina subumbrans), gamal (Gliricidia sepium), avocado (Persea americana), petai (Parkia speciosa), waru (Hibiscus tiliaceus), dan suren (Toona ciliata) that commonly found along the survey path, measurement of each tree type was repeated 10 times. The measured parameters were Index of Root Anchoring (IRA) which is the ratio of the cross-sectional area of the vertical root and the tree trunk, the vertical root is a root which has >45o from horizontal surface; and index of root binding (IRB) is the ratio of the horizontal root cross-sectional area (<45o) and the tree trunk. Sample of Lrv (total root length) and Drv (root weight) were taken using root trenching method and Drv was measured using line interception method. The trees which have high value of IRB (>1,50) are arabica coffee (Coffea arabica), lamtoro (Leucaena leucocephala), and avocado (Persea americana), whereas, trees species with high IRA (>3,00) are lamtoro (Leucaena leucocephala) and arabica coffee (Coffea arabica). Lrv, Drv and Specrol (Lrv/Drv) value will decrease with increasing soil depth value. In 0-20 cm of soil layer, the highest Lrv average value is found in arabica coffee (Coffea arabica) with a value of 0.0941 cm cm-3. The combination of various trees species with deep root and grasses or bushes with fine root is potential to maintain slope stability. A combination of various types of deep-rooted trees and grasses or shrubs that have fine and dense roots will increase the potential of the tree to maintain slope stability

Other obstract

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Item Type:	Thesis (Sarjana)
Identification Number:	SKR/FP/2019/872/052000952
Subjects:	600 Technology (Applied sciences) > 631 Specific techniques; apparatus, equipment materials > 631.4 Soil science > 631.45 Soil erosion
Divisions:	Fakultas Pertanian > Ilmu Tanah
Depositing User:	Nur Cholis
Date Deposited:	02 Oct 2020 02:48
Last Modified:	25 Oct 2021 07:25
URI:	http://repository.ub.ac.id/id/eprint/179562

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