Horsák Michal, Hájek Michal, Hájková Petra, Cameron Robert, Cernohorsky Nicole, Apostolova Iva
Department of Botany and Zoology, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic.
Naturwissenschaften. 2011 Aug;98(8):671-81. doi: 10.1007/s00114-011-0816-x. Epub 2011 Jun 18.
Mollusc communities of previously unexplored Bulgarian fens were studied in order to determine and generalise the patterns of species richness and composition along the mineral richness gradient. The aim was also to compare predictive values of the environment, vegetation and spatial structure. Altogether, 44 mollusc species were recorded at 40 treeless fen sites. Species richness varied from 0 to 18 species per site, and it was positively associated with the mineral gradient and negatively with altitude. However, the best predictor was obtained using plant species composition. All explanatory variables had higher effect on land snails than on the entire mollusc assemblage (including aquatic species). Species richness and abundance were significantly and positively correlated with the species composition turnover; the communities were highly nested, with poor sites having subsets of the fauna found in the richest. The main direction of mollusc species turnover was highly associated with that observed for vegetation, and the main gradient of plant species composition was able to explain nearly 20% of total variation in mollusc data. We found that spatial structure explained by far the highest proportion of independent variation, which reflected the high level of geographical isolation of Bulgarian fens and regional differences independent of any environmental variation. Our results demonstrate (1) the general role of mineral richness gradient for structuring mollusc communities in fens, (2) the pivotal indicator role of plant species composition in predicting species composition of mollusc communities, despite being trophically independent and (3) the effect of isolation and origins of the habitat on species composition: most species have wide geographical distributions within the habitat type, and geographical patterns within Bulgaria may have a stochastic element.
为了确定并归纳沿矿物质丰富度梯度的物种丰富度和组成模式，对保加利亚此前未被探索的沼泽地的软体动物群落进行了研究。研究目的还包括比较环境、植被和空间结构的预测价值。总共在40个无树沼泽地记录到了44种软体动物。每个地点的物种丰富度从0到18种不等，且与矿物质梯度呈正相关，与海拔呈负相关。然而，使用植物物种组成得到了最佳预测结果。所有解释变量对陆地蜗牛的影响比对整个软体动物组合（包括水生物种）的影响更大。物种丰富度和丰度与物种组成周转率显著正相关；群落高度嵌套，贫瘠地点拥有丰富地点所发现动物群的子集。软体动物物种周转的主要方向与观察到的植被周转方向高度相关，植物物种组成的主要梯度能够解释软体动物数据总变异的近20%。我们发现空间结构解释了迄今为止最高比例的独立变异，这反映了保加利亚沼泽地的高度地理隔离以及独立于任何环境变异的区域差异。我们的结果表明：（1）矿物质丰富度梯度在构建沼泽地软体动物群落方面的普遍作用；（2）尽管植物物种组成在营养上独立，但在预测软体动物群落物种组成方面具有关键指示作用；（3）栖息地的隔离和起源对物种组成的影响：大多数物种在栖息地类型内具有广泛的地理分布，保加利亚境内的地理模式可能具有随机因素。
