Is ant fauna a good bio-indicator of coastal dune ecosystems in North-East of Algeria?

Ants are good bioindicators of habitats and of their quality in many ecosystems. However, their interest in the case of coastal dunes remains to be determined because the environments are instable or subject to strong constraints. The degree of preservation of the Jijel coastal dune system is variable and presents an environmental gradient (sea-land) of five habitats defined by vegetation: upper beach, embryonic, mobile, steady and wooded dune. The aim of the study is to determine if (i) these five habitats have characteristic ant assemblages; (ii) if the variation in ant richness along the gradient shows a continuous increase reflecting very strong disturbances or shows a peak reached before the most stable habitat, therefore at the level of a medium disturbance; and (iii) how environmental factors play on the different ant species. Seventeen stations spread over four sites were selected for the study of myrmecofauna by barber trap, bait, and manual collection, and of vegetation by the quadrats method. Overall, the ant richness profile along the gradient is consistent with an increase towards the most stable environments. The composition of ant communities varies according to habitats and is correlated with the composition of plant communities. The effects on ants of environmental factors deduced from the structure of the vegetation are analysed at the community and species levels. Along the habitat gradient, there is a quadratic relationship between the barycentre and the range of habitat of the species. Despite the small number of species, this group of insects gives interesting results in terms of sensitivity to disturbances.

蚂蚁在诸多生态系统中是生境及其质量的优良生物指示物（bioindicator）。然而，沿海沙丘生境中蚂蚁的指示价值仍有待探明，因该类环境具有不稳定性且受较强约束。吉杰尔（Jijel）沿海沙丘系统的保存程度存在差异，且呈现出由植被界定的5种生境构成的海陆环境梯度：高潮滩、胚胎沙丘、流动沙丘、固定沙丘与林灌沙丘。本研究旨在明确三个核心问题：其一，上述5种生境是否各自拥有特征性的蚂蚁类群组合（ant assemblage）；其二，沿该环境梯度的蚂蚁丰富度变化，是呈现随干扰强度升高而持续递增的趋势，还是在最稳定生境之前（即中等干扰水平下）出现丰度峰值；其三，环境因子如何作用于不同蚂蚁物种。本研究选取分布于4个样区的17个采样点，采用巴氏陷阱（barber trap）诱集、诱饵诱集与人工捡拾法开展蚂蚁区系（myrmecofauna）调查，并通过样方法（quadrats method）开展植被调查。整体而言，沿环境梯度的蚂蚁丰富度变化趋势与向最稳定生境递增的规律相符。蚂蚁群落的组成随生境类型而异，且与植物群落组成显著相关。研究基于植被结构推导环境因子对蚂蚁的影响，并分别从群落与物种两个层面展开分析。沿生境梯度，物种的分布重心与其生境分布范围之间存在二次函数关系。尽管所记录的蚂蚁物种数量较少，但该昆虫类群在干扰敏感性方面展现出了颇具学术价值的研究结果。