Table_1_Testate Amoeba Species- and Trait-Based Transfer Functions for Reconstruction of Hydrological Regime in Tropical Peatland of Central Sumatra, Indonesia.XLSX

Tropical peatlands play an important role in carbon storage and in water regulation on a landscape level. However, our understanding of their ecology and long-term hydrological dynamics remains limited. Transfer functions, constructed on the basis of biological indicators (proxies) with known ecological preferences, allow us to infer past environmental conditions and serve as a basis for prediction of future changes in peatlands. Here, we use testate amoebae to develop the first species- and functional trait-based transfer functions for the Southeast Asia. This provides a valuable tool for future reconstructions of past hydrological changes in tropical peatlands, their development, and climatic changes. Surface samples for testate amoeba analysis were taken in various biotopes along two transects across the Sungai Buluh peatland in Central Sumatra. The following environmental characteristics were measured: water table depth (WTD), light intensity, pH, total C and N concentrations. The analysis of the surface samples revealed 145 morphotypes of testate amoebae belonging to 25 genera. A significant fraction of the variance in testate amoeba morphotypes and functional trait composition was explained by WTD and pH. The wide WTD range (0–120 cm) seems more valuable for reconstruction than the extremely short pH gradient (2.5–3.8). Thus, transfer functions were developed only for WTD, based on weighted averaging model for morphotypes and multiple linear regression for functional traits. Both species- and trait-based model have a predictive ability for WTD reconstruction. For traits, the best performance of the model was reached by including five morphological traits: shell width, aperture shape, aperture invagination, shell shape and shell compression. We discuss the ecology of several taxa and highlight the traits, which reflect hydrological changes in this system. Though the hydrological preferences of some species are similar to those in high and middle latitude peatlands, we argue that latitudinal differences in morphospecies composition and variations in environmental relationships of species require the development of region-specific transfer functions. Moreover, our results indicate that ecological preferences of morphotypes within morphospecies also need to be considered and included in future studies.

热带泥炭地在景观尺度的碳储存与水文调节中发挥着关键作用。但目前学界对其生态学特征与长期水文动态的认知仍较为有限。基于具有明确生态偏好的生物指标（代用指标，proxies）构建的转移函数（transfer functions），可用于反演古环境条件，并为泥炭地未来变化的预测提供理论基础。本研究以有壳变形虫（testate amoebae）为研究对象，构建了东南亚地区首个基于物种与功能性状的转移函数，可为未来热带泥炭地水文变化、发育过程及气候变化的古环境重建提供宝贵工具。本研究针对苏门答腊中部双溪乌鲁（Sungai Buluh）泥炭地的两条样带，在各类生境中采集了用于有壳变形虫分析的表层沉积物样品，测定的环境因子包括：地下水位埋深（WTD）、光照强度、pH值、总碳与总氮浓度。对表层样品的分析共检出隶属于25属的145个有壳变形虫形态型。有壳变形虫形态型与功能性状组成的显著变异，可由WTD与pH值解释。相较于跨度极窄的pH梯度（2.5~3.8），跨度更广的WTD范围（0~120 cm）更有助于古环境重建。因此，本研究仅针对WTD构建转移函数：其中形态型数据采用加权平均模型，功能性状数据则采用多元线性回归。基于物种与基于性状的模型均具备WTD重建的预测能力。就功能性状而言，纳入5个形态性状后模型可达到最优性能：壳宽、壳口形状、壳口内陷、壳形与壳压缩性。本研究探讨了若干类群的生态学特征，并重点阐明了能够反映该系统水文变化的功能性状。尽管部分物种的水文偏好与中高纬度泥炭地中的同类物种相似，但我们认为，形态种组成的纬度差异以及物种-环境关系的变异，仍需构建区域专属的转移函数。此外，本研究结果表明，未来研究还需考虑并纳入形态种内部不同形态型的生态学偏好。