凋落物输入对中亚热带不同森林细根生物量及分布的影响  

Increased litterfall regulates fine root biomass and distribution in three typical forests in subtropical China

作　　者：王微[1,2] 伍小刚[1] 胡凯[2] 陶建平[1] 

机构地区：[1]三峡库区生态环境教育部重点实验室重庆市三峡库区植物生态与资源重点实验室西南大学生命科学学院,重庆400715 [2]重庆文理学院林学与生命科学学院,重庆402168

出　　处：《生态学报》2016年第11期3391-3401,共11页Acta Ecologica Sinica

基　　金：重庆市自然科学基金计划项目(cstc2013jcyj A20019);重庆市教委科学技术研究项目(KJ131201)

摘　　要：在全球变化背景下,植物凋落物输入的改变对森林生态系统地下生态过程具有重要的影响。中亚热带森林中,细根进入凋落物层生长是一种常见现象,然而凋落物量的改变对细根生长影响的研究较少。通过对中国中亚热带针叶林、针阔混交林及常绿阔叶林这3种典型森林进行地上凋落物添加和去除实验,研究不同凋落物处理水平下细根生物量、垂直分布及形态特征的变化。结果表明:与对照(CK)相比,地上凋落物去除(LR)分别导致针叶林和针阔混交林细根总生物量显著降低40.3%和37.5%,而凋落物添加(LA)使常绿阔叶林中的细根总生物量明显提高了19.4%。不同层次的细根生物量对凋落物处理的响应不同,从针叶林到常绿阔叶林,凋落物量的改变对细根的垂直分布的影响加剧。LA处理明显提高常绿阔叶林凋落物层的细根生物量百分比(相比对照提高了10.6%)以及降低7.5—15 cm土层的细根生物量百分比(相比对照降低了10.4%)。凋落物层中生长的细根生物量和凋落物层厚度呈高度线性相关(R^2=0.742,P<0.01),并且和凋落物层生物量也呈显著线性相关(R^2=0.521,P<0.01)。3种森林类型细根的根长密度(RLD)和比根长(SRL)变化趋势与细根所处的层次紧密相关,而不同凋落物处理对它们的影响均不明显,说明细根对养分的获取策略表现为在养分丰富的凋落物层和表土层投资更多的生物量和更活跃的代谢,而不是改变细根形态的表型可塑性。Global change is potentially expected to change the quality and quantity of aboveground litter input,which could affect belowground processes of terrestrial ecosystems.Root proliferation into the litter layer in subtropical forests substantially contributes to net primary production;however,little is known concerning how increased leaf litter input affects the growth of fine roots.A litter manipulation experiment was conducted between August 2013 and August 2014 in nine stands of three different forest types in subtropical China：coniferous forest（CF）,coniferous and broad-leaved mixed forest（MF）,and evergreen broad-leaved forest（BF）.Three treatments,including litter removal（LR）,litter addition（LA）,and a control（CK） were conducted within 5 m × 5 m plots in a randomized block design in each stand.Thebiomass of fine roots（≤2 mm in diameter） in the litter layer and the 0—15 cm soil layer were measured using soil cores;root morphology was also monitored.The results showed that litter removal significantly decreased fine root biomass in CF and MF plots by 40.3% and 37.5%,respectively.Litter addition caused a slight decline in fine root biomass in CF and MF plots,but fine root biomass markedly increased（19.4%） in BF plots.The vertical distribution of fine roots differed according to litter treatments.Because CF to BF correspond to a successional gradient and increasing tree species diversity in subtropical forests,forest floor litter mass and thickness in the litter horizon increased,as did the effects of litter quantity on the vertical distribution of fine roots.Compared to the controls,litter addition plots in the relatively fertile soil of BF,resulted in a significantly higher percentage of fine roots in the litter layer,but a significantly lower percentage at 7.5—15cm depth in the mineral soil（increase of 10.6% and decrease of 10.4%,respectively）.This suggested that the results were a response to a more readily available nutrient source rather than an adaptation to nutrien

关 键 词：凋落物处理 细根生物量 细根形态 凋落物层 亚热带森林 

分 类 号：S714[农业科学—林学]