Agriculture, Ecosystems and Environment 79 (2000) 9–16 Land use effects on soil quality in a tropical forest ecosystem of Bangladesh K.R. Islam ∗ , R.R. Weil Department of Natural Resource Sciences and Landscape Architecture, 1103 H.J. Patterson Hall, University of Maryland, College Park, MD 20742, USA Received 16 July 1998; received in revised form 2 March 1999; accepted 18 October 1999 Abstract Human population pressures upon land resources have increased the need to assess impacts of land use change on soil quality. In order to assess effects of land use changes on soil quality properties in a tropical forest ecosystem of Bangladesh, soil samples were collected from adjacent well-stocked Shorea robusta natural forest, land reforested with Acacia, grassland and cultivated land. Land use/land cover changes (degradation of natural forest and subsequent cultivation of soils) resulted in surface compaction and significant decreases in silt and clay contents, porosity and aggregate stability, N, fulvic and labile C, and microbial biomass C. Maintenance respiration rates increased in comparison to the soils under natural forest. Use of soil deterioration index showed that soil quality deteriorated significantly (−44%) under cultivation, while in sites revegetated with fast-growing Acacia or grasses, it improved by 6–16%. Degradation of soil quality may have resulted from increased disruption of macroaggregates, reductions in microbial biomass, and loss of labile organic matter due to fire, deforestation, tillage and accelerated erosion. Improvement in soil quality and enhanced biological activity at reforested and grassland sites demonstrated the inherent resilience of these soils once revegetated with highly adaptable and fast growing Acacia (Acacia sp.) and grass species. ©2000 Elsevier Science B.V. All rights reserved. Keywords: Deforestation; Cultivation; Reforestation; Soil quality; Soil organic matter; Deterioration index 1. Introduction The complex integration of the primary natural resources — soil, water and vegetation, is vital for maintaining terrestrial ecosystem functions and pro- ductivity. Human poverty and a continuous decline in the amount of agricultural land per person have led to indiscriminate exploitation of natural resources in de- veloping countries of the world (Mahtab and Karim, 1992). As a result of increasing demand for firewood, ∗ Corresponding address. Tel.: +1-301-405-8922; fax: +1-301-314-9041. E-mail address: ki9@umail.umd.edu (K.R. Islam) timber, pasture, shelter and food crops, natural land covers, particularly tropical forests, are being de- graded or converted to cropland at an alarming rate (Hall et al., 1993). These trends have led to a need to assess the impacts of deforestation and conversion on soil quality. Land use changes, especially cultivation of deforested land may rapidly diminish soil quality, as ecologically sensitive components of the tropical forest ecosystem are not able to buffer the effects of agricultural practices. As a result, severe deterioration in soil quality may lead to a permanent degradation of land productivity (Kang and Juo, 1986; Nardi et al., 1996; Islam et al., 1999). Assessment of soil 0167-8809/00/$ – see front matter ©2000 Elsevier Science B.V. All rights reserved. PII:S0167-8809(99)00145-0