人工林杉木树木含水率与密度分布规律

以人工林杉木原木为研究对象，研究其水分和密度在径向和高度方向分布，以及原木气干周期，运用切片法和X射线法测试水分和密度。结果显示，在径向上，边材含水率为184.41 %，是心材与含髓心含水率的2.65倍和2.58倍；边材与含髓心材的绝干密度均为0.375 g·cm^-3，与心材绝干密度0.361 g·cm^-3存在显著性差异。X射线测试生材和绝干材密度，计算生材含水率，与切片法测试结果接近。在高度上，随树木高度增加，心材含水率逐渐下降，边材含水率有增加趋势；从根部至梢端心材绝干密度变化很小，然而，边材绝干密度有逐渐增加的趋势。径级18 cm原木初含水率126.92 %气干至25 %，气干时间约42 d，表裂严重；但气干可作为原木预干的一种方式。

The law of moisture content and oven density of plantation Chinese fir green wood

In this paper, the distribution of moisture content and density in radial and altitudinal directions of Chinese fir log were studied. The moisture content and oven density of green wood were measured by slicing and X-ray methods, the air-dry period of log was analyzed. The results showed that: in radial direction, the moisture content of sapwood was 184.41 %, which was 2.65 times and 2.58 times of that of heartwood and pithy heartwood, respectively. The oven density of sapwood and pith of heartwood were 0.375 g·cm^-3, and there was a significant difference between sapwood and pith of heartwood in oven density of 0.361 g·cm^-3. X-ray could measure the density of green and oven wood, which calculated the moisture content of green wood that was near to the result of slicing method. In altitudinal direction, with the increase of tree height, the moisture content of heartwood decreased gradually, while the moisture content of sapwood increased. The oven density of heartwood from root to tip was a constant, but the oven density of sapwood increased gradually. The initial moisture content (126.92 %) of log with diameter of 18 cm was reduced to 25 %, and the air-drying time was about 42 days, shake of log was very heavy. Air-drying can be used as a way of pre-drying log.