黄土高原南部麻栎不同群落类型乔木种群结构及演替模拟

由于对黄土高原南部麻栎天然次生林的群落稳定机制缺乏了解，以不同群落类型麻栎天然次生林为研究对象，通过样地监测及时间序列模型预测的方法，重点研究了不同群落类型中重要乔木的种群结构动态，并根据不同群落类型重要乔木种群的年龄结构数据，用时间序列模型预测未来20、30、40和50年的种群发展趋势。结果表明：（1）不同群落类型中各重要乔木种群生存能力均较好，但松栎混交林中的槲栎种群及麻栎纯林中的茶条槭种群生存能力欠佳；（2）除麻栎纯林中杜梨种群及栎阔混交林中槲栎种群，其余乔木种群的存活曲线皆呈Deevey-Ⅲ型；（3）不同麻栎群落类型中各个重要值较高的乔木种群幼龄级个体数量相对丰富，时间序列分析表明，在未来20、30、40和50年中，不同群落类型中各重要乔木种群均可持续发育，并未出现衰退迹象。同时麻栎纯林具有向混交林演替的趋势，说明未来对不同类型麻栎林经营均应以顺应自然演替规律的近自然经营方式为主。研究结果可为促进次生林持续经营及恢复提供理论依据。

Structural dynamics and succession simulation of the dominant populations in three types of Quercus acutissima community in southern of the Loess Plateau

Quercus acutissima, a broad-leaved deciduous tree of genus Quercus (oaks) in the family Fagaceae, is one of the zonally tree species in Qiaoshan of southern the Loess Plateau. There are three main types of Q. acutissima communities in this region: pure forests of Q. acutissima (PF), mixed forests of Q. acutissima with broad leaved tree like Q. wutaishansea and Q. aliena (QBF), and mixed forests of Q. acutissima and Pinus tabulaeformis (QPF). These forests are essential for regional ecological security. However, due to unreasonable initial planning and the lack of management for decades, most of the local Q. acutissima forests have been seriously destroyed with unclear inter-and intra-relationship between species. In order to investigate the succession dynamics of the main population in Q. acutissima forests and to elucidate the stabilization mechanism of the natural secondary forests, the age structure, life expectancy and survival curve of four tree populations with the highest important values in different communities (PF, QPF and QBF) were analyzed, and the succession process in the next 20, 30, 40, and 50 years were predicted by time series prediction models based on the age structure of these population. The results showed that (1) Except for Q. aliena population in Q. acutissima and P.tabulaeformis mixed forest and Acer ginnala population in Q. acutissima pure forest, other tree populations with higher importance values had better survival ability in Q. acutissima forests of different forest types; (2) The survival curves of all dominant populations were of Deevey-Ⅲ, except for the Pyrus betulifolia population in pure forests of Q. acutissima and the Q. aliena population in the mixed forests of Q. acutissima with broad leaved tree; (3) The number of young individuals of tree populations with higher importance values in different Q. acutissima community types was relatively abundant. Time series analysis showed that in the next 20, 30, 40 and 50 years, the four tree populations with the highest importance values in the three community types showed no signs of decline. In conclusion, all three types of communities could developed sustainably, and pure forests of Q. acutissim showed a tendency to evolve into broadleaves mixed forest, which indicated that the further forest management of Q. acutissima forests should all be based on the close-to-nature forest management that follows the natural succession law. Our results might provide a theoretical basis for sustainable development and management of natural secondary of Q. acutissima in southern the Loess Plateau.