【摘要】 2002年5—10月,采用连续钻取土芯法对帽儿山实验林场的水曲柳人工林细根(直径<1mm)生物量、比根长(SRL)和根长密度(RLD)的季节动态,以及它们与土壤N的有效性、土壤10cm深处月均温度和含水量的关系进行研究。结果表明:水曲柳细根生物量在春季和秋季分别具有1个明显的高峰,但比根长和根长密度只有1个高峰。在春季和夏季,比根长和根长密度较高,显示细根直径较小,而秋季,这2个参数显著下降,表明细根直径次生增厚或组织密度增加。细根的季节变化与土壤N的有效性、土壤温度和土壤含水量有重要关系。其中细根生物量与土壤铵态氮含量显著相关;硝态氮含量、10cm深处土壤的温度和土壤含水量与细根的生物量、比根长和根长密度的季节变化正相关,但均不显著(P>0·05)。4种因子的综合作用对水曲柳细根各参数的影响均达到了显著水平。不同季节细根生物量、比根长和根长密度的变化,显示出细根在生长季不同时期具有不同的生理生态功能。更多还原

【Abstract】 Fine roots turnover play an important role in carbon allocation and nutrient cycling in forest ecosystems. Seasonal dynamics of fine roots is the key for understanding the processes of fine roots turnover. From May to October in 2002, soil core method was used for estimating seasonal pattern of fine root （diameter<1 mm） parameters i.e. biomass, specific root length（SRL） and root length density （RLD） in Fraxinus mandshurica plantation located in Maoershan Experiment Station. The relationships of fine root biomass, SRL and RLD with soil N availability, average soil temperature in 10 cm depth and soil moisture were analyzed. Seasonal variation of fine root biomass was significant （P<0.05）. The peak values of fine root biomass were observed in spring and autumn, but SRL and RLD were the highest in spring and lowest in autumn. SRL and RLD were higher in spring and summer means fine root diameter was thinner, in autumn, both parameters changed to small values significantly due to secondary thickening of fine root diameter or non-structure carbohydrates accumulation. Seasonal dynamics of fine roots was associated with soil N availability, soil temperature in 10 cm depth and soil moisture. Fine root biomass has significant relationship with NH₄⁺-N availability, but less correlated with NO₃^--N availability, soil temperature in 10 cm depth and soil moisture. Correlation of fine root parameters （biomass, RLD and SRL） seasonal dynamics and multi-factors （soil available N, soil temperature and soil moisture） were significant （P<0.05）, which indicated that multi-factors were responsible to fine root dynamics. Further studies about the effects of soil temperature on SRL, RLD and non-structure carbohydrates will help us to understand fine root functions in different growing seasons and turnover of Fraxinus mandshurica plantations.更多还原