北京山区的侧柏林（Platycladus orientalis）及其生物量研究

 天然侧柏林的种类组成以菊科、禾本科植物最多，豆科、百合科、蔷薇科植物次之。组成天然侧柏林植物生活型，以地面芽和高位芽植物所占比例较大，地下芽植物次之，一年生植物的比例略高于地上芽植物。31年生人工侧柏林以胸径4—5cm、树高3—4m的植株数量最多。侧柏的胸径、树高与茎重、枝条重，叶重、根系重之间具显著相关。以胸径为自变量。树木各部分干重为应变量所获得的优化模型为：茎重(Ws)=169.82D1.92(P<0.001)，枝条重(WBr)=28.64D2.41，(P<0.01),叶重(WL)=10D2.82(P<0.001)，根系重(WR)=e4.99+0.387D(P<0.001)。由此估算得侧柏林的各器官干重：茎15.56,枝条为6.57，叶5.16，根5.29吨／公顷。乔木层的总生物量为32.58吨／公顷。林下灌木和草本层在生长季中变化明显，9月的总生物量为7.17吨／公顷。人工侧柏林总生物量为39.75吨／公顷，年平均净生产力为1.28吨／公顷。

STUDIES ON CHINESE ARBORVITAE (PLATYCLADUS ORIENTALIS) FOREST AND ITS BIOMASS IN BEIJING

The Chinese arborvitae, as an important species of silvicultural tree, is a kind of evergreen coniferous tree widely distributed in the northern part of China. It can even grow in the crevices of limestone due to its ability to endure poor soil and dry habitat. Natural secondary forests or cultivated trees are widely distributed on sunny and half-sunny slopes of mountains in the district of Beijing at elevations of 200–900m. The floristic composition of natural Chinese Arborvitae forest is mainly consisted of various species of Compositae, Graminae, Leguminosae, Liliaceae and Rosaceae. Especially, species of Compositae and Gramineae are abundance.The plant life form spectrum of Chinese arborvitae forest shows that Hemicryptophytes and Phanerophytes are rich, they make up 38% and 37% of total species, respectively. Geophytes occupy 12% of total species, Therophytes and Chamaephytes are 8% and 5%, respeetively. According to significant corelation between diameter at breast height, height of tree and the dry weight of stem, leaves and roots, the optimum models are obtained by the dry weight of various tree parts (W) against diameter at breast height of tree: W(stem) =l69.82D1.92 (P<0.001),W(branch)=28.64D2.41 (P<0.01), W(leaves)=10D2.82(P<0.001), W(roots)=e4.99+0.387D(P<0.001).The biomass of stem, branches, leaves and roots in Chinese arborvitae plantation are 15.56 t/ha., 6.57 t/ha., 5.16 t/ha. and 5.29 t/ha., respectively. The total biomass of tree layer is 32.58 t/ha. The biomass of shrub and herb layers shows seasonal change, they are 7.17 t/ha. In September. The total biomass of Chinese arborvitae plantation are 39.75 t/ha.