Faculty of Forestry and Environmental Management, University of New Brunswick, 28 Dineen Drive, Fredericton, NB, Canada.
Tree Physiol. 2011 Mar;31(3):339-48. doi: 10.1093/treephys/tpr006. Epub 2011 Apr 12.
We tested the hypothesis that moisture stress affects fine root dynamics during and after the stress. To this end, we investigated the effects of soil moisture on annual and seasonal fine root production and mortality over 4 years in a mature balsam fir (Abies balsamea L. Mill.) stand using a minirhizotron and soil coring. Droughting and irrigating treatments were imposed for 17 weeks during the third year of the study, and post-treatment recovery was measured during the fourth year. Monthly fine root production was often reduced by low soil water content (SWC) during July-September in the pre-treatment years and by imposed drought. Irrigation resulted in higher summer fine root production than in pre-treatment years. In the recovery year, increased fine root production was observed in the previously droughted plots despite low SWC in August and September. Droughting decreased year-end fine root biomass in the treatment year, but biomass returned to pre-treatment levels during the recovery year. Droughting and irrigating did not affect foliage production during the treatment and recovery years. Our results suggest that for balsam fir, establishment and maintenance of a functional balance between foliage and fine root biomass, with respect to moisture supply and demand, can depend on fine root dynamics occurring over more than one growing season. In addition, our findings provided insights into tree growth responses to interannual variation in moisture supply.
我们检验了水分胁迫影响胁迫期间和之后细根动态这一假说。为此，我们利用微根管和土壤钻在一个成熟的香脂冷杉（Abies balsamea L. Mill.）林分中，研究了土壤水分对 4 年期间细根年生产和死亡的影响。在研究的第 3 年期间，对干旱和灌溉处理进行了 17 周的处理，在第 4 年期间测量了处理后的恢复情况。在预处理年的 7 月至 9 月期间，低土壤含水量（SWC）经常导致每月细根产量减少，在预处理年和施加的干旱期间也是如此。灌溉导致夏季细根产量高于预处理年。在恢复年，尽管 8 月和 9 月 SWC 较低，但在先前干旱的地块中观察到细根产量增加。干旱导致处理年份年末细根生物量减少，但在恢复年份中恢复到预处理水平。干旱和灌溉处理在处理和恢复年份均未影响叶片产量。我们的研究结果表明，对于香脂冷杉来说，叶片和细根生物量之间的水分供应和需求之间的功能平衡的建立和维持可能取决于一个以上生长季节的细根动态。此外，我们的研究结果为树木生长对年际间水分供应变化的响应提供了新的认识。
