Point pattern analysis under conditions of replicated sampling

doi:10.17521/cjpe.2016.0383

Abstract

Abstract:

Aims The analysis of point patterns, which deals with data sets consisting of mapped locations of organisms in a study region, is especially important to plant ecological studies because the locations of plants can often be approximated as points. However, few studies used point pattern analysis with data collected by replicated sampling a principle procedure of acquiring data in ecological research. Therefore, we explore the applicability of point pattern analysis under conditions of replicated sampling in this studyMethodsThree replicated 5 m × 5 m plots of homogenous communities were established on a site with eight years of restoration in Nei Mongol steppe. In each plot, the locations of individuals in Leymus chinensis and Stipa grandis populations were mapped. O-Ring function was used to describe the population patterns and species association between L. chinensis and S. grandis for each plot as well as the integrative data of the three replicates.Important findings Population patterns and species associations differed among the three replicated plots. This illustrates that if point pattern analysis was applied to describe the population patterns and species associations only by using data from a single plot sampling, the results could be misleading. Whereas it would be more reliable to integrate the data of replicated plots in the point pattern analysis because in this way the resulting O-Ring function is a weighted average, where the weight is the number of points in the replicate i divided by the total number of points in all replicated plots.

http://jtp.cnki.net/bilingual/detail/html/ZWSB201705010

Key words: replicated sampling, point pattern analysis, O-Ring function

Xin-Ting WANG, Wei-Hua ZHANG, Chao JIANG, Cun-Zhu LIANG. Point pattern analysis under conditions of replicated sampling[J]. Chin J Plant Ecol, 2017, 41(5): 577-584.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2016.0383

https://www.plant-ecology.com/EN/Y2017/V41/I5/577

Figures/Tables 5

Table 1 Number of individuals in Leymus chinensis and Stipa grandis populations in each replicated plot on site of community with eight years of restoration

种群 Population	重复 Replicate	个体数量 Number of individuals
羊草 L. chinensis	1	2 601
	2	1 869
	3	1 970
大针茅 S. grandis	1	528
	2	512
	3	427

Fig. 1 Mapped points pattern of Leymus chinensis and Stipa grandis populations in communities with eight years of restoration (A1, A2 and A3 refer to replicates 1, 2 and 3, respectively). ○, L. chinensis; ●, S. grandis.

Fig. 2 Point pattern analysis of Leymus chinensis population in communities with eight years of restoration. -●-, observational data; --, the 95% confidence limits resulting from complete spatial random models. A, Point pattern analysis of L. chinensis population in each replicate (A1, A2 and A3 refer to replicates 1, 2 and 3, respectively). B, Point pattern analysis of L. chinensis population integrating data of three replicates.

Fig. 3 Point pattern analysis of Stipa grandis population in communities with eight years of restoration. -●-, observational data; --, the 95% confidence limits resulting from complete randomness spatial models. A, Point pattern analysis of S. grandis population in each replicate (A1, A2 and A3 refer to replicates 1, 2 and 3, respectively). B, Point pattern analysis of S. grandis population integrating data of three replicates.

Fig. 4 Spatial association between Leymus chinensis and Stipa grandis populations in communities with eight years of restoration. -●-, observational data; --, the 95% confidence limits resulting from fixed S. grandis population and random L. chinensis population. A, Spatial association between L. chinensis and S. grandis populations in each replicate (A1, A2 and A3 refer to replicates 1, 2 and 3, respectively). B, Spatial association between L. chinensis and S. grandis populations integrating data of three replicates.

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