title: Long-term responses of rainforest erosional systems at different spatial scales to selective logging and climatic change.
abstract: Long-term (21-30 years) erosional responses of rainforest terrain in the Upper Segama catchment, Sabah, to selective logging are assessed at slope, small and large catchment scales. In the 0.44 km(2) Baru catchment, slope erosion measurements over 1990-2010 and sediment fingerprinting indicate that sediment sources 21 years after logging in 1989 are mainly road-linked, including fresh landslips and gullying of scars and toe deposits of 1994-1996 landslides. Analysis and modelling of 5-15 min stream-suspended sediment and discharge data demonstrate a reduction in storm-sediment response between 1996 and 2009, but not yet to pre-logging levels. An unmixing model using bed-sediment geochemical data indicates that 49 per cent of the 216 t km(-2) a(-1) 2009 sediment yield comes from 10 per cent of its area affected by road-linked landslides. Fallout (210)Pb and (137)Cs values from a lateral bench core indicate that sedimentation rates in the 721 km(2) Upper Segama catchment less than doubled with initially highly selective, low-slope logging in the 1980s, but rose 7-13 times when steep terrain was logged in 1992-1993 and 1999-2000. The need to keep steeplands under forest is emphasized if landsliding associated with current and predicted rises in extreme rainstorm magnitude-frequency is to be reduced in scale.
authors: Department of Geography, College of Science, Swansea University, Singleton Park, Swansea SA2 8PP, UK. r.p.d.walsh@swansea.ac.uk
authors: R P D
authors: RP
authors: Walsh
authors: K
authors: K
authors: Bidin
authors: W H
authors: WH
authors: Blake
authors: N A
authors: NA
authors: Chappell
authors: M A
authors: MA
authors: Clarke
authors: I
authors: I
authors: Douglas
authors: R
authors: R
authors: Ghazali
authors: A M
authors: AM
authors: Sayer
authors: J
authors: J
authors: Suhaimi
authors: W
authors: W
authors: Tych
authors: K V
authors: KV
authors: Annammala
mesh_terms: D002588:Cesium Radioisotopes / Q000032:analysis; D057231:Climate Change; D003198:Computer Simulation; D055867:Cyclonic Storms; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry*; D055876:Landslides; D007856:Lead Radioisotopes / Q000032:analysis; D008296:Malaysia; D011891:Rain / Q000737:chemistry; D045483:Rivers / Q000737:chemistry; D013051:Spectrometry, Gamma; D013997:Time Factors; D014197:Trees / Q000737:chemistry*
chemical_list: D002588:Cesium Radioisotopes; D007856:Lead Radioisotopes