Effect of aspen (Populus tremuloides) as a companion species on the growth of black spruce (Picea mariana) in the southwestern boreal forest of Quebec
Effect of aspen (Populus tremuloides) as a companion species on the growth of black spruce (Picea mariana) in the southwestern boreal forest of Quebec
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DOI：
10.1016/j.foreco.2004.12.004
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发表时间：
2005-04
影响因子：
3.7
通讯作者：
Sonia Légaré;Y. Bergeron;D. Paré
中科院分区：
文献类型：
--
作者：
Sonia Légaré;Y. Bergeron;D. Paré
在魁北克省西部北方森林中，黑云杉林的生产力约为 1 立方米/公顷/年。这些林分的低生产力通常归因于湿地化过程，而湿地化过程是由低质量的黑云杉凋落物和黑云杉对土壤湿度的影响维持的。相比之下，白杨加速了养分循环，这表明白杨在以黑云杉为主的林分中的存在可以抵消黑云杉对土壤过程的影响，并对林分生产力产生积极影响。我们假设以黑云杉为主的林分中的白杨可以：(1) 增加黑云杉的胸径、每棵树的高度和体积，(2) 在不影响林分中黑云杉体积的情况下提高黑云杉的生产力，以及 (3) 增加林分总体积。 2001 年，对 12 个直径为 14m 的地块进行了采样，检测了三个以黑云杉为主、含有不同比例的白杨的地点的每根茎的胸径和高度。通过茎分析，确定了每个地块中三棵主要黑云杉从 5m 高度生长到 10m 高度的时间。统计分析表明，黑云杉茎的胸径、高度和体积不受白杨的影响。然而，黑云杉的总体积随着地点 2 和 3 中白杨基底面积的增加而减少，这表明白杨的存在降低了黑云杉的密度。在地点 1，黑云杉的体积没有受到白杨的影响，这表明，就林分总生产力而言，白杨纤维的净增加。沿着白杨基底面积增加的梯度，地点 1 和 3 中生长 5 m 的时间减少。这些结果表明，白杨的存在影响黑云杉的生产力，尽管这种影响是特定地点的，并且可能取决于白杨的比例、其在树冠中的等级位置以及该地点的营养状况。在某种程度上，这可以解释混合站生产力缺乏总体趋势的原因。
In the western boreal forest of Quebec, black spruce stand productivity is approximately 1m3/ha/year. The low productivity of these stands is often attributed to the paludification process, which is sustained by low quality black spruce litter and the influence of black spruce on soil moisture. In contrast, aspen hasten nutrient cycling, suggesting that the presence of aspen in black spruce-dominated stands could offset the effect of black spruce on soil processes and positively affect stand productivity. We hypothesised that aspen in black spruce-dominated stands could: (1) increase black spruce DBH, height and volume per stem, (2) increase black spruce productivity without affecting black spruce volume in the stand, and (3) increase total stand volume. In 2001, twelve 14m diameter plots were sampled for DBH and height of every stem on three black spruce-dominated sites containing various proportions of aspen. Using stem analysis, the time to grow from a height of 5m to a height of 10m was determined on three dominant black spruces in each plot. Statistical analyses revealed that DBH, height and volume per black spruce stem were not affected by aspen. However, total black spruce volume decreased with increasing aspen basal area in sites 2 and 3, suggesting that the presence of aspen reduced black spruce density. In site 1, black spruce volume was not affected by aspen, indicating, for total stand productivity, a net gain in aspen fibre. Along a gradient of increasing aspen basal area, the time to grow 5m decreased in sites 1 and 3. These results suggest that the presence of aspen influences black spruce productivity, although this influence is site-specific and could be dependent on the proportion of aspen, its hierarchical position in the canopy, and the nutrient status of the site. To some extent, this could explain the absence of a general trend concerning mixed stand productivity.