Keywords :
bacterial community, biodiversity, environmental factor, seasonal transition, soil degradation
บทคัดย่อ :
Soil biodiversity may relate to environmental changes in the soil. To determine how soil environmental factors relate to soil bacterial diversity, we compared culturable bacterial communities in soils under bare ground (BG, highly degraded), dry dipterocarp forest (DDF, moderately disturbed) and dry evergreen forest (DEF, the original vegetation) that form a degradation gradient in the Sakaerat Environmental Research Station (SERS), Thailand. The Shannon diversity and evenness and Simpson indexes were determined using the sole carbon source most probable number method. Variation patterns of these indexes were analyzed for three data sets obtained during the dry (February) to wet aune) seasonal transition. Only the March data set had significant differences in the diversity indexes among the vegetative types. In March, BG soil had a significantly lower Shannon diversity index (1.77) and evenness index (0.64) than the others (2.34 and 0.84 for DDF and 2.41 and 0.87 for DEF), and a higher Simpson index of 0.23 (0.08 for DDF and 0.07 for DEF). Repeated measures analysis of variance at p=0.05 indicated that both vegetative type and sampling time were significant sources of variation of the Shannon indexes, while only sampling time was a significant source of variation of the Simpson index. Simple and multiple regression analyses and a redundancy analysis ordination diagram showed that throughout the period of the study, soil water content was the most significant soil environmental factor with regard to the Shannon and Simpson diversity indexes. The soil bacterial communities under all the vegetative types had higher diversity and evenness in the wet months. The transition from dry to wet season had a grater effect on variation of the diversity indexes than did the soil degradation gradient.
เอกสารอ้างอิง :
Doi, R., & Sakurai, K. (2003). Soil environmental factors relating to diversity of culturable soil bacterial communities in the Sakaerat Environmental Research Station, Thailand. Tropics, 12(3), 185-200.
