不同样方尺度下鄱阳湖湿地典型草洲植物种间关联性

Species Relationship among Typical Marshland Plants in Poyang Lake Region on Different Sample Scale

摘要:

为了解群落中优势植物的关联程度和性质随样方尺度的变化，在鄱阳湖湿地典型草洲-南矶湿地国家级自然保护区选取8块样地（大小8 m×8 m，样带间隔100 m，样地间隔80 m），每个样地依次划分为1 m×1 m、2 m×2 m和4 m×4 m等3个样方尺度，利用方差比率法、卡方检验和Jaccard指数检验方法，研究群落优势植物总体关联程度和性质及两两物种对间关联程度和性质随样方尺度扩大的变化。结果表明，该研究区优势物种有灰化薹草（Carex cinerascens）、水田碎米荠（Cardamine lyrata）、蒌蒿（Artemisia selengensis）、通泉草（Mazus japonicus）、菊叶委陵菜（Potentilla tanacetifolia）、南荻（Triarrhena lutarioriparia）和早熟禾（Poa annua）。随样方尺度扩大，物种重要值除灰化薹草先增加后减少以外，其他物种的变化均不显著。7种优势植物组成的21个物种对随样方尺度扩大，植物总体关联性不显著且由负关联转向正关联。在3个样方尺度条件，21个物种对的多呈现不显著关联。随样方尺度的扩大，种间呈显著关联的物种对逐渐减少；种间呈正关联的物种对逐渐增加。Jaccard指数表明，各物种对随样方尺度的扩大，种间关联程度不断增加。这是由于研究区地被植物种类较多，分布频度较低，不同样方尺度下，群落内部资源分布差异以及物种之间的竞争与协同关系所致。

关键词:鄱阳湖;湿地;草洲植物;样方尺度;种间关联

Abstract:

In order to understand the changes in species relationship of dominant species with sample scale, a typical wetland in the Poyang Lake region, the Nanji Wetland National Nature Reserve was selected as the study area, three belt transects with spacing interval 100 m were surveyed, which consisting of 2-3 sample plots (8 m×8 m in size) with sample spacing interval 80 m for each transect, eight sample plots in total. Each sample plot was divided into three sample unit scales with spatial sizes of 1 m×1 m, 2 m×2 m and 4 m×4 m. The methods of variance ratio test, χ² test, Jaccard index were used to measure the change tendency of overall interspecies association and pair interspecies association for the community dominant plants with expansion of the sample unit scales. The results showed that Carex cinerascens, Cardamine lyrata, Artemisia selengensis, Mazus japonicus, Potentilla tanacetifolia, Triarrhena lutarioriparia, and Poa annua were dominant species according impotance value. With increase of sample unit scale, the changes in importance value of dominant species were not significant except of Carex cinerascens, which increased at first and then decreased. According to variance ratio test, there were no significant difference in overall interspecies association for the 21 species pairs from the seven dominant species, and which changed from negative association to positive association with the increment of the sample unit scale. From χ² test, there was no significant difference in species-species association for most of the 21 species pairs at the three sample unit scales. With enlargement of sample unit sizes, the number of species pairs with significant association dropped down and that with positive association stepped up gradually. According to Jaccard index, the degree of species pair association enhanced continuously with increment of sample unit scales. Therefore, it was caused that there were many plant species with low occurrence frequency, the resources distribution variation within plant communities at different sample scales and the competition/cooperation relations between plant species in the study area.

Key words:Poyang Lake region;Wetland;Marshland species;Sample scale;Species relationship