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Soil degradation and rehabilitation in humid tropical forests (Sabah, Malaysia)

Ilstedt, Ulrik (2002). Soil degradation and rehabilitation in humid tropical forests (Sabah, Malaysia). Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Silvestria, 1401-6230 ; 249
ISBN 91-576-6333-5
[Doctoral thesis]

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Physical degradation of soil, reductions in plant growth, and increases in the frequency of wild fires are common consequences of forest operations in humid tropical forests. However, there is little available information on the interaction of plant growth, soil nutrients and microbial properties, especially in connection with man made rehabilitation of these soils. Therefore, the objectives of the work described in this thesis were as follows. Firstly, to quantify the effect of skid tracks in a forest plantation in Sabah, Malaysia, on the soil´s physical, chemical and biological properties, as well as plant production. Thirdly, to test and develop assays based on measurements of microbial respiration kinetics for assessing soil degradation and rehabilitation. Fourthly, to assess the effects of fire in a humid tropical Dipterocarp forest on the soil´s chemical and microbial properties. In the study area, where rehabilitation were tested, the growth, soil nutrient content, and soil pore distribution were severely affected by crawler tractors. About 10 days with little rain resulted in water potentials close to the permanent wilting point (-1500 kPa) irrespective of the type of amendments applied, while outside skid tracks the soil dried at a slower rate. Fertilization and tilling of the tracks increased basal area growth of Acacia mangium from 1 to 7 m²ha⁻¹yr⁻¹, despite high soil bulk densities. Two years after the treatments many soil microbial properties had improved, although they had not returned to the levels observed outside the tracks. Microbial growth kinetics were shown to be promising tools for assessing the effect of soil disturbance and rehabilitation. The recommended water content for measurements of microbial respiration kinetics in Acrisols was -15 to -50 kPa. The effect of fire was either minor or positive on soil nutrient pools (partly due to the extensive leaf shedding that followed it), as measured by chemical methods. In contrast, microbially available N decreased by about 50%.

Authors/Creators:Ilstedt, Ulrik
Title:Soil degradation and rehabilitation in humid tropical forests (Sabah, Malaysia)
Series Name/Journal:Acta Universitatis Agriculturae Sueciae. Silvestria
Year of publishing :April 2002
Number of Pages:38
ALLI. Ilstedt, U., A. Nordgren and A. Malmer. 2000. Optimum soil water for soil respiration before and after amendment with glucose in humid tropical acrisols and a boreal mor layer. Soil Biology and Biochemistry 32, 1591-1599. II. Ilstedt, U., R. Giesler, A. Nordgren and A. Malmer. 2002. Changes in soil chemical and microbial properties after a wildfire in a tropical rainforest in Sabah, Malaysia) (Manuscript.) III. Ilstedt, U., P. Liau, A. Nordgren and A. Malmer. 2002. Tractor Disturbance and Rehabilitation after Logging: Tree Production and Soil Physical Properties in a Tropical Plantation (Sabah, Malaysia) (Manuscript.) IV. Ilstedt, U., A. Nordgren and A. Malmer. 2002. Tractor Disturbance and Rehabilitation after Logging: Soil Chemical and Microbial Properties in a Tropical Plantation (Sabah, Malaysia) (Manuscript.)
Place of Publication:Umeå
ISBN for printed version:91-576-6333-5
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:P Natural resources > P36 Soil erosion, conservation and reclamation
Subjects:Not in use, please see Agris categories
Agrovoc terms:acrisols, soil degradation, tropical rain forests, acacia mangium, forest plantations, mechanical damage, tracks, soil pore system, soil microorganisms, soil chemistry, nutrient availability, reclamation, growth, forest fires, sabah
Keywords:Acrisol, nutrient availability, pore structure, rainforest, reclamation, restoration, ultisol
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ID Code:233
Department:(S) > Institutionen för skogsekologi (930701-061231)
Deposited By: Staff Epsilon
Deposited On:11 Apr 2003 00:00
Metadata Last Modified:02 Dec 2014 10:02

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