黄土高原不同气候区刺槐细根表面积的差异

Difference of Surface Area of Fine Roots of Robinia pseudoacacia in the Different Climate Regions of Loess Plateau

以生长在黄土高原半干旱气候区陕西省安塞县和半湿润气候区甘肃省泾川县的刺槐人工林为研究对象,采用土钻法获取根样和土样,研究不同气候区刺槐细根表面积垂直分布、季节动态及其与林地土壤水分的相关性。结果表明:安塞和泾川刺槐细根垂直分布深度、细根表面积数量和季节动态均有一定的差异。0～200cm和0～150cm土层分别为安塞和泾川刺槐细根表面积的主要分布层,分别有86.5%和87.6%的细根表面积分布。2007年生长季内,泾川和安塞刺槐细根表面积的峰值分别出现在4月和6月,但6月份安塞与泾川刺槐的累积细根表面积差异不显著。与泾川刺槐细根表面积特征相比,安塞刺槐细根表面积表现为,减小单位土体内细根表面积数量,增大细根垂直分布深度,以维持树木生长所需要的细根表面积总量。

Ansai County and Jingchuan County are respectively located in the semiarid and semihumid region of the Loess Plateau of China. By using soil coring method,the seasonal dynamics of surface area of fine roots and soil water content in Robinia pseudoacacia forests were investigated in Ansai County and Jingchuan County. The results showed that the vertical distribution of fine roots,the fine root surface area of R. pseudoacacia and its seasonal dynamics were different between Ansai County and Jingchuan County. Around 86. 5% of total fine root surface area was in the 0 - 200 cm soil layer in Ansai County,while the 87. 6% of total fine root surface area was distributed in the 0 - 150 cm soil layer in Jingchuan County. In the growing season in 2007,the highest value of fine root surface area was observed in April in Jingchuan County,while it was in June in Ansai County. The difference of total fine root surface area between Ansai and Jingchuan was not significant in June. By comparing the characteristic of fine root surface area in Ansai County with the characteristic of fine root surface area in Jingchuan County,the R. pseudoacacia in Ansai County reduced the density of fine root surface area,however increased the vertical depth of fine root distribution to maintain the total fine root surface area for tree growth.