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种群是构成群落的基本单位,也是理解植物群落结构组成与动态变化机制的关键[1]。种群年龄结构不仅反映不同种群大小和年龄个体的组配情况,也反映了种群数量动态及其发展趋势[2-3]。近年来,国内出现了以种群结构为研究内容的报导。但多数学者,像刘贵峰[4]、涂云博[5]、袁志忠[6]等只是单纯地针对种群结构进行研究,并没有涉及种群在群落中的分布情况。然而,研究植物分布格局对揭示种群的形成和维持机制有着重要的理论意义,与种群结构的研究相辅相成,一直以来都是植物生态学领域的研究热点[7]。国内的学者也相应地做了一系列的工作。蒙荣[8]等运用地统计学的方法,对短花针茅荒漠草原群落优势种群进行了空间格局分析;张金屯[9]和李素清[10]等,则分别应用DCA排序与格局分析方法相结合、DCA排序与双项轨迹方差法相结合的方法,完成了对相关种群分布格局的研究;两人又在2008年共同阐述了随机配对法在亚高山草甸优势种群格局分析中的应用[11]。然而,这些研究都是基于一种或几种固定尺度下进行的,没有把空间格局与尺度变化有机的结合起来。为了克服这些问题,近年来,对于物种空间格局的研究,多采用点格局分析法的K函数[12-15],并且出现了一系列的研究进展。张金屯[16]在阐述植物空间点格局分析时应用K函数对美国密歇根州克林顿县栎林的3个优势种群进行了研究;杨晓晖[17]等对白刺沙堆进行空间格局分析;宋于洋[18]等则对梭梭种群不同发育阶段的空间格局及其关联性进行了分析。通过这些学者的研究可以说明多尺度点格局分析是格局分析方法的重大突破。但K函数因其存在显著的尺度累积效应(即小尺度累积效应影响大尺度格局分析结果)。因此,通过圆环代替K函数中圆以有效消除尺度累积效应的O-ring函数便应运而生,并很快应运到各类种群点格局分析中[19]。
干热河谷属生态脆弱区,土壤侵蚀严重[20-22],以“南亚热带为基带的立体气候”高温、干旱、蒸发量大,这里植物物种较为稀少,但中国特有物种和濒危物种在此均有分布[23],发育着以草地和多汁、带刺灌木为主的河谷特殊类型半稀树草原、稀树草原植物群落[24]。国内干热河谷森林群落主要分布在云南和四川两省[24],目前对干热河谷森林群落的研究主要集中在云南省干热河谷群落结构[25]、植物生物量[26]、生物多样性[27-28]、植物对土壤养分和水分的利用[29]等方面。四川攀枝花苏铁国家级自然保护区内1500 m~2300 m,主要为干热河谷次生稀树灌木林,是干热河谷特殊类型稀树、半稀树草原植物群落—干热河谷稀树灌木林经人为干扰(放牧)退化后,常年受季节性焚风效应影响,在山体背风坡形成以低矮灌木和草本植物为建群种的次生稀树灌木林群落,并处于向气候顶极(干热河谷常绿针阔叶混交林[24])演替的次生演替初级阶段。目前,基于永久固定样地的干热河谷植物群落动态及演替的研究还较鲜见,对四川攀枝花苏铁国家级自然保护区内干热河谷次生稀树灌木林的研究更是尚未起步。研究基于四川攀枝花苏铁国家级自然保护区干热河谷次生稀树灌木林内1 hm2固定样地,通过分析优势种群组成、空间分布格局及种间关联性,以期较为全面地掌握该群落内优势种群现状、分布状况及发展动态,旨在为干热河谷稀树灌木林乃至整个干热河谷生态系统的演替和生物多样性维持机制的研究奠定物种动态及空间格局方面的基础。
Research on Spatial Pattern and Interspecific Association of Dominant Populations in Secondary Savanna Shrub Forest in Dry-hot Valley
doi: 10.12172/202109020002
- Received Date: 2021-09-02
- Available Online: 2022-03-14
- Publish Date: 2022-06-09
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Key words:
- Dominant population /
- Spatial pattern /
- Interspecific association /
- Secondary savanna shrub forest in dry-hot valley /
- Panzhihua Cycas panzhihuaensis National Nature Reserve
Abstract: In order to understand spatial pattern and interspecific association of dominant populations in secondary savanna shrub forest in dry-hot valley, a 1 hm2 permanent sample plot was established in Panzhihua Cycas panzhihuaensis National Nature Reserve. The individual plants of all populations in the sample plot were investigated per tree, the dominant population composition of the community was analyzed by the important values, and the spatial pattern, interspecific association, and relationships of aggregation scale and dominance of dominant populations in community were executed by using function O-ring and software SPSS. The results showed that the dominant species in the secondary savanna shrub forest in dry-hot valleys were trees or small trees except Cycas panzhihuaensis. The spatial distribution pattern of the six dominant populations was all random distribution, which was followed by aggregation distribution, and the proportion of uniform distribution scale was the smallest. The dominance of population increased with the increase of aggregation scale, and there was a positive linear correlation between them. The regression equation was y = (127.49 ± 9.04)x + (4.78 ± 1.88) (Adj-R2 = 0.98, P = 1.46993E-4 < 0.01). The proportion of interspecific correlation scale was the largest in non-correlation, followed by negative correlation and the smallest in positive correlation. The dominance of populations in community was determined by aggregation scale, which was also the main driving force to change dominant position of populations in community. The main survival pressure of Terminalia franchetii was from C. panzhihuaensis and Morus mongolica, which was also easily affected by community environment. The main reason for regulating twice of intraspecific density was interspecific competition from Quercus cocciferoides and M. mongolica, as well as T. franchetii and M. mongolica.