Page 86 - 《广西植物》2022年第12期
P. 86

2 0 7 6                                广  西  植  物                                         42 卷
                        ( 1. College of Biology and Chemistry Engineeringꎬ Panzhihua Universityꎬ Panzhihua 617000ꎬ Sichuanꎬ Chinaꎻ
                          2. National Nature Reserve of Cycas panzhihuaensisꎬ Panzhihua 617000ꎬ Sichuanꎬ Chinaꎻ 3. Panzhihua
                                     Construction Engineering Schoolꎬ Panzhihua 617000ꎬ Sichuanꎬ China )


                 Abstract: In order to reveal dynamics of community succession of a secondary savanna shrub forest of the arid ̄hot valley
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                 in National Nature Reserve of Cycas panzhihuaensis in Sichuanꎬ based on the first (2020) reexamined data of 1 hm
                 permanent fixed plot which was established in 2015ꎬ community dynamics over the past five years were analyzed by
                 species compositionꎬ community diversityꎬ importance valueꎬ mortality rateꎬ recruitment rate and diameter at breast
                 height (DBH). The results were as follows: (1) Woody plants in community changed from 15 familiesꎬ 17 generaꎬ and
                 17 species in 2015 to 15 familiesꎬ 18 generaꎬ and 18 species in 2020. There was no significant change for dominant
                 species composition but a significant change for degree of dominance in the past five years. For the six common
                 populations with higher importance values (>1) in 2020ꎬ the importance values of five populations increasedꎬ and the
                 population of C. panzhihuaensis decreased onlyꎬ when compared with their importance values in 2015. C. panzhihuaensis
                 was still the most dominant species and constructive species in the plotꎬ but its importance value declined
                 significantly. Howeverꎬ a significant increase of importance values occurred for some arbor species such as Quercus
                 cocciferoides and Terminalia franchetii. (2) The number of woody plants with DBH≥1 had increased to 1 710 until
                 2020ꎬ the average DBH of all woody plant individuals in this community increased from 11.10 cm to 11.17 cm. The
                 average annual mortality was 0.29%ꎬ and the average annual recruitment rate was 2.75%ꎬ the average DBH of dead and
                 recruited individuals were 11.84 cm and 4.96 cm respectively. Compared with the woody plants living in 2015ꎬ individual
                 trees from seven species had diedꎬ and those from nine species were recruited over the past five years. (3) The results
                 also indicated that although Osyris quadripartita declinedꎬ the populations of nine species increasedꎬ and four were stable
                 from 2015 to 2020. The average DBH of Cycas panzhihuaensis and Osyris quadripartita decreased onlyꎬ but the others
                 increased to different extents. With forest successionꎬ the importance of interspecific competition within community will
                 increase gradually. Dominant position in community will be occupied by arbor tree species such as Quercus cocciferoides
                 and Terminalia franchetii during process of succession in the futureꎬ but dominant position of Cycas panzhihuaensis is not
                 threatened in a short term. The main reason of significant decrease of dominance of Cycas panzhihuaensis is plant
                 individual death of larger diameter class. In the futureꎬ a transitional ̄type secondary community from secondary savanna
                 shrub forest to climax which is occupied by arbor tree species gradually will been consisted of Cycas panzhihuaensisꎬ
                 Quercus cocciferoidesꎬ Terminalia franchetii and other arbor trees.
                 Key words: species compositionꎬ community diversityꎬ community successionꎬ secondary savanna shrub forest of the
                 arid ̄hot valleyꎬ National Nature Reserve of Cycas panzhihuaensis




                森林生物多样性的形成与维持机制可以从不                            构和特 征 的 研 究ꎬ 国 外 学 者 已 在 喜 马 拉 雅 山 区
            同尺度进行研究ꎮ 在群落尺度上ꎬ物种多样性形                             (Shaheen et al.ꎬ 2012 )、 巴 拿 马 森 林 皆 伐 迹 地
            成和维持机制与森林群落的结构特征密不可分                               (Hooper et al.ꎬ 2004)、马来西亚热带森林( Khairil
            (臧润国等ꎬ2001)ꎮ 森林群落结构和物种组成动                          et al.ꎬ 2014) 以 及 热 带 山 地 云 雾 林 ( Shi & Zhuꎬ
            态不仅是生态系统过程和功能的基础ꎬ也是生物                              2009)等不同类型的森林群落开展了相关研究ꎬ并
            与环境长期相互作用的结果ꎬ其能够影响森林生                              发现森林群落结构与海拔、坡度、人为活动和林火
            态系统固碳、物质周转率(Xiao et al.ꎬ 2014)ꎬ反映                  干扰以及土壤特性等因素密切相关ꎮ 更有学者比
            群落生产力大小( Zhang & Chenꎬ 2015) 和群落抵                  较研究放牧与非放牧条件下ꎬ水分梯度对群落植
            抗干扰的恢复能力( Jayakaran et al.ꎬ 2014)ꎬ还可               物物种丰富度( richness)、多样性( diversity) 以及

            进一步为研究森林群落的演替规律(Tilman et al.ꎬ                     群落物种组成的影响规律( Meyers et al.ꎬ 2014)ꎬ
            2006)ꎬ揭示物种共存、生物多样性维持机制提供                           发现人为干扰和水分梯度影响与植物群落结构和
            重要信息(Loreau et al.ꎬ 2001)ꎮ 关于森林群落结                 物种多样性相背离的空间自相关现象ꎬ也阐明了
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