INTEGRATIVE EVALUATION OF REHABILITATIVE EFFECTS OF ACACIA AURICULIFORMIS ON DEGRADED SOIL

Multivariate soil profiling was applied to determine the rehabilitative effects of 17-and 18-year-old Acacia aunculiformis plantation plots on a degraded land in Thailand. Soils were sampled from the A. aunculiformis plantation plots, a dry evergreen forest (the original vegetative type) and bare ground (the most degraded vegetation) in Sakaerat, Thailand. The soils were profiled by (1) physico-chemical measurements; (2) antibiotic disc diffusion method for soil bacterial community; and (3) long bean growth measurements. Soil dehydrogenase activity, as a soil microbial activity indicator, was also measured. No variables showed differences between soils of the dry evergreen forest and the plantation. Most of the physico-chemical and long bean variables showed clear differences between the bare ground soil and soils of the dry evergreen forest and the A. aunculiformis plantation. The bacterial variables showed less distinctive differences between the soils profiled. The land degradation was explained in terms of deteriorated soil physico-chemical conditions and crippled biotic functions. The principal components and discriminant analyses of the data sets for the methods and for all the variables indicated that the A. aunculiformis plantation soil had been restoring its original soil conditions, including abiotic properties and biotic functions. For rehabilitating degraded lands in the Thai savanna region, it would be practical and effective to plant A. aunculiformis. Pemprofilan tanah pelbagai pemboleh ubah digunakan untuk menentukan kesan pemulihan Acacia aunculiformis berumur an tara 17 tahun hingga 18 tahun ke atas tanah ternyahgred di negara Thai. Tanah disampel daripada plot A. aunculiformis, hutan malar hijau kering (tumbuhan asli) dan tanah gondol di Sakaerat, negara Thai. Tanah diprofil secara (1) ukuran fiziko-kimia; (2) kaedah resapan cakera antibiotik bagi mengesan komuniti bakteria tanah dan (3) ukuran panjang lenggai. Aktiviti dehidrogenase tanah sebagai penunjuk aktiviti mikrob tanah juga disukat. Tiada perbezaan diperhatikan antara tanah hutan malar hijau kering dengan tanah ladang Acacia. Kebanyakan pemboleh ubah fizikokimia dan panjang lenggai menunjukkan perbezaan ketara antara tanah gondol dengan tanah hutan malar hijau kering dan ladang A. aunculiformis. Pemboleh ubah bakteria menunjukkan perbezaan kurang ketara antara tanah berlainan. Tanah dianggap ternyahgred apabila keadaan fiziko-kimianya merosot dan fungsi biotanya lumpuh. Komponen