Temporal and spatial variation of Myriapoda (Diplopoda and Chilopoda) assemblages in a Neotropical floodplain

Abstract: Myriapods constitute important edaphic macrofauna taxa which dwell in different trophic levels and influence the dynamics of these environments. This study evaluated the variation in composition, richness and abundance of edaphic myriapod assemblages as a function of the distribution and structure of flooded and non-flooded habitats (spatial variation) and hydrological seasonality (temporal variation) in a floodplain of the northern Pantanal region of Mato Grosso, Brazil. Sampling was carried out in three areas of the Poconé Pantanal, along an altitudinal and inundation gradient consisting of inundated and non-inundated habitats and different vegetation formations. Three quadrats (10 x 10 m) were delimited within each habitat type, where sampling was performed using pitfall traps and mini-Winkler extractors during the dry, rising water, high water and receding water periods of two hydrological cycles within the Pantanal (2010/2011 and 2011/2012). A total of 549 millipedes were collected, consisting of 407 Diplopoda and 142 Chilopoda distributed in six orders, 12 families and 20 species. The assemblages composition varied throughout the seasonal periods, indicating that the rising water and dry periods differed from the high water and receding water periods. In addition to the variation between seasonal periods, myriapod richness and abundance also varied in relation to areas consisting of different vegetation formations. Thus, it can be concluded that the hydrological seasonality associated with the inundation gradient and different vegetation types were determinant in the heterogeneous spatial and temporal distribution of myriapod assemblages, validating that the conservation of these invertebrates in the Pantanal is directly linked to the preservation of vegetation, and consequently, ecosystem integrity.

摘要：多足类（Myriapods）是一类重要的土壤大型动物群（edaphic macrofauna），栖息于不同营养级并对这类生境的动态过程产生影响。本研究以巴西马托格罗索州潘塔纳尔（Pantanal）北部泛滥平原为研究区域，针对土壤多足类群落的组成、物种丰富度与多度变化展开评估，分析其与淹水及非淹水生境的分布与结构（空间变异）、水文季节动态（时间变异）之间的关联。采样工作于潘塔纳尔波科内（Poconé）地区的三个样区开展，沿海拔与淹水梯度设置了淹水、非淹水生境及不同植被类型样地。每类生境内划定3个10×10米的样方，于潘塔纳尔两个水文周期（2010/2011年、2011/2012年）的旱季、涨水期、高水位期和退水期，采用陷阱法（pitfall traps）与迷你温克勒提取器（mini-Winkler extractors）开展采样。本次研究共采集到549只多足类标本，其中倍足纲（Diplopoda）407只、唇足纲（Chilopoda）142只，隶属于6个目、12个科、20个物种。群落组成随季节周期发生显著变化，结果显示涨水期与旱季的群落组成显著区别于高水位期与退水期。除季节周期的变异外，多足类的物种丰富度与多度同样因不同植被类型的样区而存在差异。综上，本研究证实：与淹水梯度相关的水文季节动态以及不同植被类型，是决定多足类群落空间与时间异质性分布的关键调控因子；同时验证了潘塔纳尔地区这类无脊椎动物的保护，直接关联于植被的保护，进而维系生态系统的完整性。