摘要
An investigation was conducted to quantify fine roots and roots nodules over the four seasons in forestry and agroforestry alder （Alnus rubra） stands in North Wales. Soil samples collected in each season were excavated at three sampling points （0.30 m, 0.57 m and 1.00 m distance from the base of each tree） from nine trees of the agroforestry and forestry plots. Result showed that the density of live fine root had significant differences in between seasons and treatments （P 〈 0.001）. The mean weight density of live fine root over the four seasons in agroforestry and forestry was 0.27±0.01 kg·m^-3 and 0.54±0.03 kg·m^-3, respectively. Weight density of dead root in each system remained constant throughout the year. The mean weight density of dead root was also significantly different （P 〈 0.01） between forestry and agroforestry systems. Weight density of live and dead root nodule was both constant throughout the year and between the different sampling distances. The mean weight densities of live and dead root nodule over the four seasons were 0.09±0.03 kg·m^-3 and 0.05±0.03 kg·m^-3 in agroforestry and 0.08±0.02 kg·m^-3 and 0.03±0.01 kg·m^-3 in the forestry plots, respectively.
对北威尔士桤木林份和复合林份内健康根系和根瘤的四季变化进行了调查和量化。分别在桤木林和复合林中选取9株树木,距树木基部0.30m,0.57m和1.00m的3个取样点掘取土壤样品。结果表明,不同季节或处理的健康根系密度存在显著差异(P<0.001)。桤木林和复合林内,桤木健康根系的四季平均重量密度分别是0.27±0.01kg·m-3和0.54±0.03kg·m-3。两种林份内,死亡根系的重量密度在四季均保持恒定;但林份间存在显著差异(P<0.01)。健康或死亡的桤木根系重量密度在全年内基本恒定,不同取样点间的差异也不显著。复合林内,健康或死亡根瘤在四季的平均重量密度分别是0.09±0.03kg·m-3和0.05±0.03kg·m-3;纯林内两种根瘤的平均密度分别是0.08±0.02kg·m-3和0.03±0.01kg·m-3。图3表3参20。
