基于两个不同资源轴上苔藓植物生态位分析

分别以群丛类型和生长基质类型(包括树生、石生、土生)作为资源轴,对小秦岭56个样方中苔藓植物的生态位特征进行分析和对比。结果表明:(1)两种资源轴上苔藓物种的生态位特征存在一定差异,不同资源轴上,苔藓物种生态位宽度排序发生一定改变。两种资源轴上,青藓属(Brachythecium)均具有较大的生态位宽度,而酸土藓属(Oxystegus)和叶苔属(Jungermania)在不同资源轴上生态位宽度差异较大。(2)对比两种资源轴上的生态位重叠值,生长基质类型明显高于群丛类型;在不同资源轴上,个别物种生态位重叠值排序还会发生明显改变。树平藓属(Homaliodendron)与金灰藓属(Pylaisiella)在两种资源轴上表现出完全相反结果。(3)与维管植物相似,生态位宽度较大的苔藓物种生态位重叠值高,生态位宽度小的苔藓物种也会有较大生态位重叠。

Ecological niche of bryophytes based on two resource axes

Bryophytes, which are relatively primitive species among higher plants, are an important component of biodiversity. The ecological adaptability of species varies based on resource space. This study was conducted in the small Xiaoqinling Mountains Nature Reserve, which was located in Lingbao in Western Henan Province. This location was rich in plant resources; the geographical coordinates are 34°23''-34°31''N, 110°23''-110°44''E. Using stratified sampling and a coastal wave height setting, fifty-six 20 m × 20 m representative sample plots were selected, and the trees, shrubs, herbs, and bryophytes were surveyed and sampled. The multiple regression tree method was used for the 56 plots. Elevation, slope, and aspect were independent variables, and 405 vascular plants in the 56 plots were used to determine the importance value of these dependent variables for community classification. The 56 sample plots were divided into five cluster types and defined as different resource bases, according to the determination of bryophyte epiphytic substrates, which were divided into trees and rocks characteristic of different resource niches. In two different resource axes, 15 types of importance values were chosen. The largest included the order Jungermanniales. Mosses included both acrocarpous and pleurocarpous types. The niche breadth and overlap values of the 15 selected groups were determined using the Shannon-Wiener niche index and Levins niche overlap value. The effects of association between substrate types (trees, rock, and soil) as resource axes on the niche characteristics of bryophytes were examined and compared among the 56 sites. The results showed the following: (1) The two resource axes of niche characteristics of bryophytes differed. On different resource axes, breadth varied among different bryophyte species. In particular, the breadth of Brachythecium was greater. The breadths of Oxystegus and Jungermania in the two types of resource axes differed. In the two resource axes, Brachythecium had a larger niche breadth, ecological adaptability, and environmental utilization ability, whereas the niche width of Homaliodendron was smaller, narrower, and exhibited weaker ecological adaptability. Oxystegus and Jungermania niche widths differed between the resource axes. (2) The niche overlap values of the substrate for the two resource axes were significantly higher than those of association types. The niche overlap order of individual species on different resource axes also differed. Homaliodendron and Pylaisiella showed the opposite results. (3) Similar to that observed in vascular plants, in bryophyte species, niche overlap was high with large niche breadth. Bryophyte species with small niche breadth could also exhibit large niche overlap. For example, Brachythecium had a large niche breadth, whereas the other species had large niche overlap values. However, Oxystegus and Fissidens exhibited niche widths that were small, although they still exhibited large niche overlap values, thereby demonstrating that a certain degree of similarity existed in the use of both resources.