北京九龙山侧柏生态公益林空间结构分析与评价

[目的]分析侧柏生态公益林空间结构并进行经营迫切性评价,为侧柏生态公益林空间结构的优化调整及区域内其它生态公益人工林空间结构优化调整奠定理论基础。[方法]基于北京九龙山侧柏生态公益林的实测数据,选取混交度、大小比数、角尺度、密集度、林层指数、开敞度和竞争指数7个空间结构参数分析侧柏生态公益林的空间结构特征,并从密度、格局、竞争和混交等方面选取10个指标构建了经营迫切性评价指标体系并确定评价标准,进而对侧柏林进行了经营迫切性评价。[结果]侧柏生态公益林空间结构较为简单,林分呈均匀分布,树种组成单一,以零度和弱度混交为主,呈现单种聚集趋势;林木大小分化不明显,侧柏的优势度最大;林木之间较为密集,处于很密集和比较密集的林木比例较高;林分中所有林木几乎都分布在中林层与上林层,林层指数为0.288,林层结构不太明显;林分开敞度和竞争指数分别为0.274和0.318,总体处于生长空间不足、中度竞争状态;侧柏林的经营迫切性指数为0.8,经营迫切性等级为特别迫切,说明侧柏人工林大多数状态特征不符合标准,急需通过采取有效的经营措施优化林分配置,改善森林状况,以实现侧柏人工林可持续发展的目的。[结论]林分空间结构的分析与经营迫切性评价,不仅能够发现林分结构的不合理方面,还能针对性的制定空间结构调整措施,促进侧柏生态公益林不断向健康稳定的方向发展,实现其生态、经济和社会效益的持续发挥。

Analysis and Evaluation of Stand Spatial Structure of Platycladus orientalis Ecological Forest in Jiulongshan of Beijing

[Objective] This study aims at providing a theoretical basis for the optimization and adjustment of the spatial structure of the Platycladus orientalis ecological forest and the optimization of the spatial structure of other ecological forest in the region by analyzing the spatial structure of P. orientalis ecological forest and evaluating its management urgency.[Method] Based on the data field-measured at P. orientalis ecological forest in Jiulongshan of Beijing, the spatial structure characteristics of P. orientalis ecological forest were analyzed by using seven spatial structure parameters including the mingling, dominance, uniform angle index, crowding, stand layer index, open degree and competition index. 10 indices were selected to conduct the evaluation index system of management urgency from the aspects of density, pattern, competition and mingling, and the standards were established. Meanwhile, the management urgency of P. orientalis ecological forest was evaluated.[Result] The spatial structure of the P. orientalis ecological forest was relatively simple, the pattern of distribution was random, the tree species composition was single, the trees of non-mixture and low-mixture were dominant, and showed a trend of single aggregation. The tree size differentiation was insignificant, and the P. orientalis was in an obviously dominant position and with higher stand density. It contained a higher proportion of dense and very dense trees; most trees were in the middle and upper layers, and its layer index was 0.288, suggesting that the layer structure was not obvious; the stand open degree and competition index were 0.274 and 0.318 respectively, which were in the state of insufficient growth space and moderate competition. The management urgency index of the P. orientalis forest was 0.8, and its grade of management urgency were particularly urgent, indicating that most characteristics of P. orientalis ecological forest did not meet the standards. It is needed to take effective measures to optimize the forest allocation and improve forest condition in order to achieve sustainable development of P. orientalis ecological forest.[Conclusion] Analyzing the stand spatial structure and evaluating its management urgency can find the unreasonable characteristics of forest structure, and develop the adjustment measures of space structure, so as to promote the development toward the healthy and stable direction for P. orientalis ecological forest, and achieve continuous gain of the ecological, economic and social benefits.