武夷山落叶林木本植物细根性状研究

Fine root traits of woody plants in deciduous forest of the Wuyi Mountains

细根作为植物吸收水分与养分的重要器官,其性状特征在指示植物的生长和分布等方面的意义重大。以江西武夷山国家级自然保护区落叶林群落木本植物的细根为对象,对根氮含量(RNC)、根磷含量(RPC)、根氮磷比(RN∶P)、根组织密度(RTD)、比根长(SRL)和比根面积(SRA)等6个细根性状进行了研究,并对群落内不同物种以及不同结构单元(灌木和乔木)间细根性状的差异性进行分析。结果表明:武夷山落叶林群落木本植物的平均RNC为(10.27±3.11) mg/g、平均RPC为(0.63±0.17) mg/g、平均RN∶P为16. 36±2. 61、平均RTD为(0. 10±0. 02) g/cm^3、平均SRL为(1582.65±186.67) cm/g、平均SRA为(464.81±64.10) cm^2/g;灌木的SRL显著高于乔木(P=0.033),其余细根性状在灌木和乔木之间无显著差异(P> 0.05);在细根性状中,RNC与RPC呈极显著正相关,但与RTD呈显著负相关,RPC、SRA分别与RTD呈极显著负相关,RPC、SRL分别与SRA呈极显著正相关。这可能反映了灌木倾向于通过增加SRL来提高水分和养分的获取能力以增强与乔木的竞争优势;群落中的植物通过改变SRA及RTD进行生长与防御之间的权衡。

As important organs for plants to absorb water and nutrients,fine roots are of great significance in indicating the growth and distribution of plants.In order to better understand the variation of fine root traits across species and structural units (shrubs and trees),here we collected fine roots of woody plants in deciduous forest of the Wuyishan National Nature Reserve,Jiangxi Province,and studied their traits including root nitrogen content (RNC),root phosphorus content (RPC),root nitrogen and phosphorus ratio (RN :P),root tissue density (RTD),specific root length (SRL),and specific root surface area (SRA).We found that the mean values of chemical traits:RNC,RPC and RN :P of woody plants in the studied deciduous forest were (10.27±3.11)mg/g,(0.63±0.17)mg/g and 16.36±2.61,respectively.The mean values of morphological traits,RTD,SRL and SRA were (0.10±0.02)g/cm3,(1582.65±186.67)cm/g and (464.81±64.10)cm^2/g,respectively.The SRL of shrubs was significantly higher than that of trees (P=0.033),but there were no significant differences in other fine root traits between shrubs and trees (P >0.05).The RNC was positively correlated with RPC but negatively with RTD;the RTD was negatively correlated with both RPC and SRA;the SRA was positively correlated with both RPC and SRL.These results suggest that shrubs tend to increase the accessibility of water and nutrients by increasing its SRL to enhance its competitive advantage over trees,and that woody plants in deciduous forest make a trade-off between growth and defense by changing their SRA and RTD.