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）类群，栖息于不同营养级并调控这类土壤生境的生态动态。本研究以巴西马托格罗索州北部潘塔纳尔泛滥平原为研究区域，以淹水与非淹水栖息地的分布与结构（空间变异）及水文季节节律（时间变异）为驱动因子，评估了土壤多足类群落的组成、物种丰富度与丰度变化。采样工作于潘塔纳尔波科内片区的三个区域开展，沿海拔与淹水梯度设置了淹水、非淹水栖息地及不同植被类型样地。每个栖息地类型内划定3个10×10米样方，于2010/2011与2011/2012年两个潘塔纳尔水文周期的枯水期、涨水期、高水位期与退水期，采用陷阱法（pitfall traps）与迷你温克勒提取器（mini-Winkler extractors）完成采样。本次研究共计采集到549头多足类标本，其中倍足纲（Diplopoda）407头、唇足纲（Chilopoda）142头，隶属于6个目、12个科与20个物种。分析结果显示，群落组成随季节周期发生显著分化：涨水期与枯水期的群落组成与高水位期、退水期存在显著差异。除季节节律带来的群落变异外，不同植被类型区域的多足类丰富度与丰度亦存在显著差异。综上可知，与淹水梯度相关的水文季节动态及不同植被类型，是决定多足类群落在空间与时间上异质分布的核心调控因子；该结果验证了潘塔纳尔湿地内这类无脊椎动物的保护，与植被保护乃至生态系统完整性的维护直接相关。