天然红海榄种群分布格局研究

Spatial distribution patterns of natural Rhizophora stylosa population

关键词:  红海榄种群  天然林  分布格局  空间尺

Key words:  Rhizophora stylosa  natural forest  distribution patterns  spatial scales

摘要:

以湛江高桥红树林自然保护区中的天然红海榄种群为对象,采用相邻格子法进行野外调查,同时根据红海榄种群个体定位图,运用扩散系数、聚集指数、聚块性指数、扩散型指数、平均拥挤度、负二项参数、Cassie.R.M.指标,分析天然红海榄种群在不同潮带、不同群落类型及不同取样尺度下的空间分布格局。结果表明:红海榄种群在高潮带和低潮带中趋向于随机分布的空间格局,中潮带则呈现为明显的聚集分布; 红海榄种群在纯林中的分布格局略偏向于随机型,在混交林中则呈现较强的聚集分布,聚集度指标表现为C >1,I_δ>1,K<8,m^*/x^->1,C_a>0; 红海榄种群在不同取样尺度的分布格局存在差异,聚集强度随着取样尺度的增大而减弱,在取样尺度为5 m×5 m时呈现明显的聚集分布,取样尺度为5 m×10 m时亦表现为聚集分布但聚集强度相对较小,取样尺度为10 m×10 m时其空间格局介于聚集分布与随机分布的临界状态。红海榄种群的分布格局与生境条件的异质性以及红海榄自身的生物学特性有关。

Abstract:

According to the map of individual location,the distribution patterns of natural Rhizophora stylosa population were investigated in different tidal zones with different sampling scales at Gaoqiao Mangrove Nature Reserve applying 7 aggregation indices such as diffusion coefficient,aggregation index,patchiness index,dispersal index,mean crowding index,negative binomial parameter and Cassie index,and field data were obtained by tallying with contiguous grid quadrate method. The results showed that the natural R. stylosa population tended to be distributed randomly in high-and low-tide belts,while to be aggregative in the mid-tide belt. Furthermore,its distribution pattern tended slightly to randomness in pure forest,while to high aggregation in mixed forest,C >1,I_δ>1,K<8,m^*/x^->1,C_a>0. Although,the spatial patterns of Rhizophora stylosa population differed at various spatial scales,the aggregation intensity of the population decreased with increment of sampling scale,the population showed aggregation pattern obviously at 5 m×5 m,aggregation pattern with relatively lower intensity at 5 m×10 m,and critical status between aggregation and random at 10 m×10 m sampling scale. It was correlated with heterogenicity of environmental conditions and its biological characteristics.