Variation in density of Picea sitchensis in relation to within-tree trends in tracheid diameter and wall thickness
Variation in density of Picea sitchensis in relation to within-tree trends in tracheid diameter and wall thickness
复制标题
锡琴云杉密度变化与树内管胞直径和壁厚趋势的关系
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
M. Denne
中科院分区：
文献类型：
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作者：
M. D. Mitchell;M. Denne
总结了形成层年龄和年轮宽度对锡特卡云杉密度的影响。对管胞直径和细胞壁厚度与树内趋势的关系进行了分析。从威尔士三个不同地点的七个林分中，从总共24棵树的胸高处采集了圆盘，在胸高处，其中一个林分的总树高分别为30%和60%。在幼龄材上，轮数越多，轮数越小，径向管胞直径越大。这些总体趋势被认为是树木生长所固有的，可能与形成层老化有关，因为它们发生在所有地点的所有树木中。在幼龄木材中，密度也随形成层年龄的部位生长速率(用年轮宽度表示)而变化，较宽的年轮与管胞直径随年轮数量变化的速度更快，管胞壁厚的减少有关。因此，与生长速度较慢的地点相比，在生长速度较快的地点，幼林密度下降得更快，下降到更低的最小值。在成熟木材中，随着年轮宽度的增加，密度的降低与管胞直径和壁厚的差异有关。胸高处的密度略高于(但不显著)30%总高度处的可比年轮，与胸高处明显较厚的管胞壁有关。径向管胞直径(年轮数或年轮宽度)的变化与早材的差异大于向每个生长轮的晚材端的差异，而壁厚随年轮宽度的变化与壁厚向晚材端的增加速率有关。这可能解释了以前关于营林管理对密度的影响的一些相互矛盾的报道，因为密度可能会随着环境对形成层活动的季节性周期的影响而变化。
Summary The influences of cambial age and ring width on density of Sitka spruce {Picea sitchensis (Bong.) Carr) were analysed in relation to within-tree trends in tracheid diameter and cell wall thickness. Discs were sampled at breast height from a total of 24 trees, from seven stands at three contrasting sites in Wales, and at breast height, 30 per cent and 60 per cent total tree height from one of the stands. Across the juvenile wood, ring density decreased with ring number from the pith while radial tracheid diameter increased. These overall trends were considered to be inherent to tree growth, presumably associated with cambial ageing, since they occurred in all trees on all sites. In juvenile wood, density also varied with site growth rate (as indicated by ring width) at similar cambial age, wider rings being associated with more rapid rate of change in tracheid diameter with ring number and with decrease in tracheid wall thickness. Consequently, on a site having trees with high growth rate density decreased more rapidly across the juvenile wood, down to a lower minimum value, than on sites with a slower growth rate. In mature wood, the decrease in density with increase in ring width was associated with differences in both tracheid diameter and wall thickness. Density was slightly (though not significantly) higher at breast height than in comparable rings at 30 per cent total height, associated with significantly thicker tracheid walls at breast height. Changes in radial tracheid diameter (with ring number, or with ring width) were associated with greater differences in the earlywood than towards the latewood end of each growth ring, while variations in wall thickness with ring width were associated with rate of increase in wall thickness towards the latewood end. This may account for some previously conflicting reports on influence of silvicultural management on density, for density is likely to vary with influence of environment on the seasonal cycle of cambial activity.