摘要
以青海共和盆地东缘5、10、15、20、25年生青杨人工林为研究对象,采用根钻取土芯法收集细根,分析0~20、20~40、40~60、60~80、80~100 cm各土层深度细根生物量、生物量密度、比根长、比表面积、根表面积密度和根长密度的差异。结果表明,20年生青杨人工林以5~7 cm径级(65.63%)、3~4 m高度级(34.38%)乔木占比最大,且均显著高于其他4个林龄的林分;青杨人工林生物量密度主要分布在0~60 cm土层,占细根总量的73.20%~76.92%,其数值随林龄增大呈增大趋势;随着不同林龄的增加,0~60 cm土层根表面积密度和根长密度占总量的80.42%和76.71%,60~80 cm的土层占8.79%和10.27%,80~100 cm的土层占10.78%和13.01%;青杨人工林生物量密度、比根长、比表面积、根表面积密度和根长密度均随林龄的增大而增大;通过RDA分析表明土壤钾离子、土壤含水量和林龄与根长密度、根表面积密度、比表面积呈显著正相关,与土壤pH、硝酸根离子呈负相关。研究认为,青杨人工林根系随林龄的增大逐渐向深层发展,不同林龄青杨人工林细根分布的差异表明群落地下分配模式不同,需要在今后研究中深入探索分配差异的机理;青杨人工林发育20 a后,可进行合理抚育,促进细根发育,最大程度发挥其生态效益。
Five-,10-,15-,20-,and 25-year-old P.cathayana plantations in the east edge of Gonghe Basin in Qinghai Province were used as the research objects to examine the fine root biomass and morphological characteristics.The soil coring method was used to collected fine roots.Relative data were measured,such as fine root biomass,biomass density,specific root length,specific surface area,root surface area density,and root length density at different soil depths of 0-20,20-40,60-80,and 80-100 cm,from which the differences were analyzed.The results showed that the arbors of 5-7 cm diameter class(65.63%)and 3-4 m height class(34.38%)figured most prominently in the 20-year-old P.cathayana plantation,and they were greatly higher than those of the other four stands.The biomass density of P.cathayana plantation mainly distributed in the 0-60 cm soil layer,accounting for 73.20%-76.92%of the total fine roots,and its value went up with the forest ages.With the increase of forest ages,the root surface area density and root length density in 0-60 cm soil layer accounted for 80.42%and 76.71%of the total,60-80 cm soil layer for 8.79%and 10.27%,80-100 cm soil layer for 10.78%and 13.01%.The biomass density,specific root length,specific surface area,root surface area density and root length density of P.cathayana plantation increased with forest age.Redundancy analysis(RDA)showed that soil potassium ion,soil water content and forest age were positively correlated with root length density,root surface area density and specific surface area,but negatively correlated with soil pH and nitrate ion.The study indicates that the root system of P.cathayana plantations will gradually grow to the deep layer with the forest ages.The difference of fine root distribution in P.cathayana plantations with different ages implies that the patterns of community underground distribution are different.Researchers must further explore the mechanism of distribution differences in future.After 20 years of growth,the P.cathayana plantations can be moderately tended to promote the growth of fine roots and maximize its ecological benefits.
作者
杨向东
邓磊
YANG Xiang-dong;DENG Lei(College of Agriculture and Forestry,Qinghai University,Xining 810016,Qinghai,China;Qinghai Guinan Desert Ecosystem Positioning Observation and Research Station,National Forestry and Grassland Administration,Guinan 813100,Qinghai,China)
出处
《西北林学院学报》
CSCD
北大核心
2023年第2期8-16,131,共10页
Journal of Northwest Forestry University
基金
青海省自然科学基金(2020-ZJ-945Q)
青海省重点研发与转化计划(2022-NK-168)
中央财政林业科技推广项目(青〔2022〕TG01号)。
关键词
青杨人工林
恢复年限
细根分布
形态特征
P.cathayana plantation
restoration age limit
fine root distribution
morphological characteristics
