Biodiversity of arbuscular mycorrhizal (AM) colonization and AM fungal spores were studied in the roots and rhizosphere soils of Acacia catechu (L.f). Wild., A. mangium Willd, Anthocephala cadamba Miq., Artocarpus chaplasha Roxb., Chickrassia tabularis A. Juss., Swietenia macrophylla King., Tectona grandis L. from plantations; Albizia procera (Roxb.) Benth., A. falcataria L., Alstonia scholaris (L.) R. Br., Aphanamixis polystachya (Wall.) Parker., Hydnocarpus kurzii (King.) Warb., Heynea trijuga Roxb., Lagerstroemia speciosa (L.) Pers., Messua ferrea Linn., Podocarpus nerifolia Don., Swintonia floribunda Griff., Syzygium fruticosum (Roxb.) DC., S. grandis (Wt.) Wal. from forest and nursery seedlings of A. polystachya, A. chaplasha, Gmelina arborea Roxb. and S. cuminii (L.) Skeels from Hazarikhil forest, Chittagong of Bangladesh. Roots were stained in aniline blue and rhizosphere soils were assessed by wet sieving and decanting methods. The range of AM colonization varied significantly from 10%-73% in the plantations samples. Maximum colonization was observed in A. mangium (73%) and minimum colonization was observed in C. tabularis (10%). Vesicular colonization was recorded 15%-67% in five plantation tree species. The highest was in A. cadamba (67%) and the lowest was in T. grandis; A. chaplasha and C. tabularis showed no vesicular colonization. Arbuscular colonization was recorded 12%-60% in four plantation tree species. The highest was in A. mangium (60%) and the lowest was in A. cadamba. Roots of Artocarpus chaplasha, C. tabularis and T. grandis showed no arbuscular colonization. Among 12 forest tree species, nine tree species showed AM colonization. The highest was in A. falcataria (62%) and the lowest was in S. fruticosum (10%). Significant variation in vesicular colonization was recorded in seven forest tree species. The highest was in H. trijuga (52%) and the lowest was in L. speciosa (18%). Hydnocarpus kurzii, M. ferrea, P. nerifolia S. fruticosum and S. grandis showed no vesicular colonization. Arbuscular colonization was recorded in seven forest tree species. The highest was in A. falcataria (60%) and the lowest was in A. procera (10%). All the nursery seedlings showed AM colonization and the range was 10%-73%. Vesicules were recorded in G. arborea (40%) and S. cumini (40%). Arbuscular colonization was recorded in G. arborea (100%) and S. cumini (100%). Spore population was recorded 77-432/100 g dry soils, 80-276/100 g dry soils, and 75-153/100g dry soils in plantation, forest and nursery, respectively. Glomus and Acaulospora were dominant genera among the six AM fungi recorded. Significantly positive correlation was observed between AM colonization and AM fungal spore population in Hazarikhil plantation tree species, forest tree species and nursery tree seedlings. The present study showed the biodiversity of root colonization and AM fungi are active in nutrient cycling, survivals and seedling establishment of the plants in the Hazarikhil forest, plantation and nursery. Biodiversity of arbuscular mycorrhizal (AM) colonization and AM fungal spores were studied in the roots and rhizosphere soils of Acacia catechu (Lf). Wild., A. mangium Willd, Anthocephala cadamba Miq., Artocarpus chaplasha Roxb., Chickrassia tabularis A. Juss ., Swietenia macrophylla King., Tectona grandis L. from plantations; Albizia procera (Roxb.) Benth., A. falcataria L., Alstonia scholaris (L.) R. Br., Aphanamixis polystachya (Wall.) Parker., Hydnocarpus Kurgeii (King.) Warb., Heynea trijuga Roxb., Lagerstroemia speciosa (L.) Pers., Messua ferrea Linn., Podocarpus nerifolia Don., Swintonia floribunda Griff., Syzygium fruticosum (Roxb.) DC., S. grandis ( Wt.) Wal. From forest and nursery seedlings of A. polystachya, A. chaplasha, Gmelina arborea Roxb. And S. cuminii (L.) Skeels from Hazarikhil forest, Chittagong of Bangladesh. Roots were stained in aniline blue and rhizosphere soils were assessed by wet sieving and decanting methods. The range of AM colonization substantially significantly Maximum colonization was observed in A. mangium (73%) and minimum colonization was observed in C. tabularis (10%). Vesicular colonization was recorded 15% -67% in five plantation tree The highest was in A. cadamba (67%) and the lowest was in T. grandis; A. chaplasha and C. tabularis showed no vesicular colonization. Arbuscular colonization was recorded 12% -60% in four plantation tree species. highest was in A. mangium (60%) and the lowest was in A. cadamba. Roots of Artocarpus chaplasha, C. tabularis and T. grandis showed no arbuscular colonization. Among 12 forest tree species, nine tree species showed AM colonization. The The highest was in A. falcataria (62%) and the lowest was in S. fruticosum (10%). Significant variation in vesicular colonization was recorded in seven forest tree species. was in L. speciosa (18%). Hydnocarpus kurzii, M. ferrea, P. nerifolia S. fruticosum and S. granThe highest was in A. falcataria (60%) and the lowest was in A. procera (10%). All the nursery seedlings showed AM colonization and the range (40%) and S. cumini (40%). Arbuscular colonization was recorded in G. arborea (100%) and S. cumini (100%). Spore population was recorded 77-432 / 100 g dry soils, 80-276 / 100 g dry soils, and 75-153 / 100g dry soils in plantation, forest and nursery, respectively. Glomus and Acaulospora were dominant genera among the six AM fungi recorded. Significantly positive correlation was observed between AM colonization and AM fungal spore population in Hazarikhil plantation tree species, forest tree species and nursery tree seedlings. The present study showed the biodiversity of root colonization and AM fungi are active in nutrient cycling, survivals and seedling establishment of the plants in the Hazarikhi l forest, plantation and nursery.