Finnish Forest Research Institute, Vantaa Research Unit, FI-01301 Vantaa, Finland.
Tree Physiol. 2010 Jan;30(1):103-15. doi: 10.1093/treephys/tpp099. Epub 2009 Dec 2.
We studied experimentally the effects of water availability on height and radial increment as well as wood density and tracheid properties of Norway spruce (Picea abies (L.) Karst.). The study was carried out in two long-term N-fertilization experiments in Southern Finland (Heinola and Sahalahti). At each site, one fertilized and one control plot was covered with an under-canopy roof preventing rainwater from reaching the soil. Two uncovered plots were monitored at each site. The drought treatment was initiated in the beginning of growing season and lasted for 60-75 days each year. The treatment was repeated for four to five consecutive years depending on the site. Altogether, 40 sample trees were harvested and discs sampled at breast height. From the discs, ring width and wood density were measured by X-ray densitometry. Tracheid properties were analysed by reflected-light microscopy and image analysis. Reduced soil water potential during the growing season decreased annual radial and height increment and had a small influence on tracheid properties and wood density. No statistically significant differences were found in the average tracheid diameter between the drought-treated and control trees. The average cell wall thickness was somewhat higher (7-10%) for the drought treatment than for the control, but the difference was statistically significant only in Sahalahti. An increased cell wall thickness was found in both early- and latewood tracheids, but the increase was much greater in latewood. In drought-treated trees, cell wall proportion within an annual ring increased, consequently increasing wood density. No interaction between the N fertilization and drought treatment was found in wood density. After the termination of the drought treatment, trees rapidly recovered from the drought stress. According to our results, severe drought due to the predicted climate change may reduce Norway spruce growth but is unlikely to result in large changes in wood properties.
我们通过实验研究了水分可利用性对挪威云杉（Picea abies (L.) Karst.）高度、径向生长、木材密度和管胞特性的影响。该研究在芬兰南部的两个长期氮施肥实验中进行（Heinola 和 Sahalahti）。在每个地点，一个施肥和一个对照小区被一个遮雨棚覆盖，以防止雨水到达土壤。每个地点都监测了两个未覆盖的小区。干旱处理在生长季节开始时进行，每年持续 60-75 天。根据地点的不同，处理重复了四到五年。总共收获了 40 棵样本树，并在胸高处取样圆盘。从圆盘上，通过 X 射线密度计测量了年轮宽度和木材密度。管胞特性通过反射光显微镜和图像分析进行分析。生长季节土壤水势的降低减少了年径向和高度生长，并对管胞特性和木材密度产生了较小的影响。在干旱处理和对照树木之间，未发现平均管胞直径有统计学上的显著差异。与对照相比，干旱处理的细胞壁厚度平均高（7-10%），但在 Sahalahti 只有统计学上的显著差异。早材和晚材管胞的细胞壁厚度都有所增加，但晚材的增加幅度更大。在干旱处理的树木中，年轮内细胞壁比例增加，从而增加了木材密度。在木材密度方面，氮施肥和干旱处理之间没有发现相互作用。干旱处理结束后，树木迅速从干旱胁迫中恢复。根据我们的结果，由于预计的气候变化导致的严重干旱可能会减少挪威云杉的生长，但不太可能导致木材性质发生大的变化。
