封育年限对武夷山毛竹细根功能性状的影响

Effects of enclosure term on fine root functional traits of moso bamboo(Phyllostachys edulis)in the Wuyi Mountains

自然封育是培育森林资源重要且有效的途径,细根作为植物体重要的资源获取型器官,在森林群落发挥生态功能中扮演重要角色。为明晰自然封育对毛竹细根功能性状的影响,采用空间代替时间的研究方法,以武夷山国家公园内正常经营和封育年限为3、5、10、15年和40年的毛竹林作为研究对象,揭示不同封育年限下毛竹细根功能性状的差异以及对土壤理化性质变化的适应规律。结果表明:(1)封育年限对毛竹细根的功能性状具有显著影响。随着封育年限的增长,毛竹细根的比根长、比根面积、全碳、全氮和全磷含量均呈现先上升后下降的变化趋势,组织密度、碳氮比和碳磷比呈现先下降后上升的趋势,同其他封育毛竹林群落相比,封育10和15年的毛竹林群落中细根比根长、比根面积和养分含量得到显著提高。土壤层次和细根径级对细根功能性状同样具有显著影响。(2)毛竹细根功能性状间随封育年限的变化存在显著的相关性。比根长、比根面积、全碳含量、全氮含量和全磷含量彼此之间存在显著的正相关关系,与碳氮比、碳磷比和组织密度存在显著的负相关关系。(3)随着封育演替进程,毛竹林群落中土壤因子的变化驱动着细根功能性状发生改变,土壤容重同细根养分含量呈显著的负相关关系,土壤碳磷含量与细根比根长和比根面积存在显著的正相关关系,土壤养分含量与细根养分含量呈现极显著正相关关系。综上,自然封育促使毛竹细根通过自身表型可塑性合理权衡不同功能性状之间的资源配置,当封育10—15年,毛竹细根将更多养分集中于资源获取型性状的构建,吸收能力和效率显著提高,林分生产力和生态功能较优,在封育10—15年后适当进行科学的人为经营活动有助于毛竹林的可持续健康发展。

Natural enclosure refers to the forest in a closed state,which is extensively believed to be an important and effective approach to cultivating forest resources.Fine roots,as the important resource-acquiring organ of plants,are crucial to the ecological function fulfillment of forest communities.To clarify the effects of natural enclosure on the fine root functional traits,the moso bamboo(Phyllostachys edulis)forests under human management and enclosure for 3,5,10,15 years,and 40 years in the Wuyi Mountain National Park were chosen as the research objects,using the method of substituting space for time,to compare the differences in the fine root functional traits of moso bamboo and investigate their adaptations to the changes of soil physical and chemical properties under different enclosure years.The results indicated that:(1)The natural enclosure had a significant effect on the functional traits of moso bamboo fine roots.With the increase of the enclosure year,the specific root length(SRL),specific root area(SRA),total carbon(C),total nitrogen(N)and total phosphorus(P)content of moso bamboo fine roots showed a trend of increasing and then decreasing,and root tissue density(RTD),the C∶N and C∶P ratio showed a trend of decreasing and then increasing.Compared with other natural enclosure forests,the SRL,SRA and nutrient content of fine roots in the moso bamboo forest community enclosure for 10 and 15 years were significantly improved.The soil layer and diameter class had significant effects on fine root functional traits equally.(2)There was a significant correlation between the functional traits of moso bamboo fine roots with the changes of enclosure year.SRL,SRA and nutrient content had significantly positive correlations,and they had significantly negative correlations with C∶N,C∶P and RTD.(3)With the successional process of enclosure,the changes of soil factors in the moso bamboo forest community drove the changes of the fine root functional traits.There was a significantly negative correlation between soil capacity and fine root nutrient contents.The C and P content of soil were significantly positively correlated with the SRL and SRA of fine roots.The soil nutrient contents showed a highly significant positive correlation with the fine root nutrient contents.In conclusion,the natural enclosure prompted the fine roots to reasonably weigh the allocation of resources between different functional traits through their phenotypic plasticity.After 10-15 years of the natural enclosure,the moso bamboo fine roots concentrated more nutrients on the construction of resource-acquisitive traits,with significantly higher absorption capacity and efficiency,the stand productivity and ecological functions being superior.Appropriately scientific human management activities after 10-15 years of natural enclosure would contribute to the sustainable and healthy development of moso bamboo forests.