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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。
The quaternary changes of healthy roots and nodules in the North Wales alder and composite stands were investigated and quantified. Soil samples were taken from three mulberry trees and three mixed forests, respectively. Three soil samples were collected from three sampling points of 0.30m, 0.57m and 1.00m at the base of trees. The results showed that there was a significant difference in healthy root density in different seasons or treatments (P <0.001). In the Alnus cremastogyne forest and the composite forest, the average weight density of healthy roots of Alnus cremastogyne was 0.27 ± 0.01 kg · m-3 and 0.54 ± 0.03 kg · m-3, respectively. In both stands, the weight density of dead roots remained constant throughout the seasons, but there was a significant difference between the stands (P <0.01). The root weight density of healthy or dead alder was basically constant throughout the year, with no significant difference between sampling points. In the composite forest, the average weight density of healthy or dead nodules was 0.09 ± 0.03kg · m-3 and 0.05 ± 0.03kg · m-3 respectively in the four seasons. The average density of the two nodules in the pure forest was 0.08 ± 0.02kg · m- 3 and 0.03 ± 0.01 kg · m-3. Figure 3 Table 3 Reference 20.