Details

Autor(en) / Beteiligte

• Malmer, A.
• Grip, H.

Titel

Soil disturbance and loss of infiltrability caused by mechanized and manual extraction of tropical rainforest in Sabah, Malaysia

Ist Teil von

• Forest ecology and management, 1990-12, Vol.38 (1), p.1-12

Ort / Verlag

Amsterdam: Elsevier B.V

Erscheinungsjahr

1990

Quelle

Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)

Beschreibungen/Notizen

• The rate of infiltration, or infiltrability, is known to change due to soil disturbance. The infiltrability is normally higher in the initial stages of infiltration before wetting of the soil, when pressure gradients predominate over the gravitational forces. This is described by the term ‘sorptivity’ which is the cumulative infiltration as a function of the square root of time, which often is constant during early stages of infiltration. As gravitation starts to dominate, infiltrability decreases to a constant-rate, steady-state infiltrability. Drastic changes in infiltrability may lead to overland flow causing erosion and nutrient leaching. Dry bulk density, steady-state infiltrability and sorptivity were measured in reference forest and after manual and crawler-tractor timber extraction in different watersheds on Orthic Acrisol (40% clay, 40% sand) and Gleyic Podsol (10% clay, 80% sand). Six-year-old tractor tracks after selective logging were also investigated. New tractor tracks covered 24% of the mechanically extracted area, while skid rails covered 4% of the manually extracted area. In the top 10 cm, mean dry bulk density increased after all treatments, but was significant only in the top 5 cm on clay soil after tractor extraction, where it increased from 0.82 to 1.28 g cm −3. Means of steady-state infiltrability and sorptivity were lower on treated areas than in the forest. Differences of mean steady-state infiltrability were significant for all tractor treatments compared with reference forest on both soil types and also with manual extraction on clay soil. On clay soil (and sand) mean stead state infiltrabilities were 154 (48.7), 36.7 (11.6), 0.28 (1.26) and 0.63 (−) mm h −1 in forest, on manual and on new and old tractor tracks respectively.