Reconstructing past structure and nitrogen accumulation of free populations, and test of its accuracy

通过将该技术应用于已有26年历史的东野冷杉人工林，并比较估算和观察到的森林结构，我们测试了现有样本中树木种群结构和功能重建方法的准确性。取样于2000年10月在札幌市日久冈试验林施肥试验田进行。在对照区和年施肥区分别测定了树径、树高、树冠长等指标。然后砍倒10棵树，测量它们的植物部分生物量值。采用茎瓣估算边材面积。还收集了茎盘进行茎分析，以估计茎的体积和生长情况。2001年10月又进行了一次抽样。然后，对所有样品进行分析，得出树高与植株部位、生长等之间的异速生长关系。采集树木样品进行氮浓度分析：干燥、研磨，用N- c分析仪进行氮浓度分析。研究林分中存在单株树胸径的时间序列数据。利用树木异速生长的附加信息，我们估算了总林分、植物部分生物量、叶面积、生长等。在没有样地数据的年份，我们采用Osawa et al.（2000）的林分重建方法，估算了总林分结构和氮含量。还分析了茎氮浓度与边材体积、边材体积与树长、茎粗分布之间的关系。我们发表了两篇关于林分重建理论估算精度的论文。

We tested accuracy of the method for structural and functional reconstruction of tree populations from the existing samples, by applying this technique to a 26-year-old plantation of Todo-fir, and comparing the estimated and observed structures of the forests. Sampling was done in Oct. 2000, at a fertilization experiment plots in Hitsujigaoka Exp. Forest in Sapporo. Tree dbh, height and crown length etc. were measured in both control and annually fertilized plots. Then ten trees were felled, and their plant-part biomass values were measured. Stem discs were taken for estimation of sapwood areas. Discs were also collected for stem analysis for estimation of stem volume and growth. Additional sampling was done in Oct. 2001. Then, all samples were analyzed together to develop allometric relationships between tree size and plant part, growth, etc. Tree samples were also collected for analysis of nitrogen concentration: they were dried, ground, then analyzed with the N-C analyzer for N concentration. Time series data of dbh exists for individual trees in the studied stands. With the additional information of tree allometry, we estimated for the total stands, plant-part biomass, leaf area, their growth etc. For the years without plot data, we applied the stand reconstruction method of Osawa et al. (2000), and total stand structure and nitrogen content were estimated. Also analyzed for this calculation were relationships between stem nitrogen concentration vs. sapwood volume, sapwood volume vs. tree size, and stem size distribution. We published two original papers on accuracy of estimates in the theory of stand reconstruction.