Up to about 15 years ago a deciduous forest in the Nam Wa sub-watershed was increasinglyencroached for agricultural purposes. Then, about 15 years ago, the local people and the local authority in LaiNan District cooperated to conserve this forest area through natural succession. This study was carried on thequantitative floristic characteristics, soil organic matter and soil nutrients with the aim of identifying the impactof the disturbance. The trees’ database in the area and land use history were used to classify the area into fivedegrees of disturbance as follows; i) very high (orchard); ii) high (abandoned crop field with 15 years of naturalsuccession); iii) medium (most trees were logged 15 years or more ago and then left to succession), iv) low(some trees were logged 15 years or ago and then left to succession); and iv) very low (small number of treeswere logged). The results indicate that the density and basal area is the lowest in the very high disturbance areaand the highest in the low disturbance area. Indeed the measured characteristics of the soil differ significantlyamong the disturbance areas (ANOVA: P<0.05), and therefore, that the quantitative characteristics of thisdisturbed forest have not completely recovered after 15 years of natural succession. The soil chemistry at twosoil depths: 0 - 20 cm and 20 - 40 cm does not vary for most soil chemical properties measured. The pH, organicmatter, total nitrogen, available phosphorus and exchangeable potassium show no statistically significantdifference between each of the sites with different degrees of disturbance nor between the two soil depths at eachsite. It is therefore possible that soil organic matter and some soil nutrients are recovered after 15 years of forestsuccession.for an accurate dose determination using the Monte Carlo method.
การแปล กรุณารอสักครู่..
