Context

Describing the hydrogeomorphic character of rivers in a holistic way is essential to understanding the processes whereby freshwater ecosystems maintain patterns of biodiversity and ecosystem processes. A key question in carrying out this characterisation is the temporal and spatial scales which best represent differences and similarities between habitats.

Objectives

The purpose of this study is to describe the hydrological and geomorphological character of a large river-floodplain system (the Upper Mississippi River, USA) at multiple spatial and temporal scales in order to holistically determine the physical template influencing the riverine ecosystem.

Methods

Seventeen variables are used to describe the hydrogeomorphic character of 99 backwaters and floodplain lakes along a 100 km reach of the river.

Results

At the landscape scale (10 s of km), position in the landscape and proximity to neighbouring habitats contributed most to variability in hydrogeomorphic character. At the smaller patch scale (10–100 s of m), the shape of entry to the patch and water depth were distinguishing variables. In relation to temporal variables, habitats are distinguished by decadal scale variables describing the historic nature of the rise and fall of connection events, and mean peak and duration of connection over long periods. In contrast, the interplay of magnitude and duration of individual connection events produced unique patterns at the short-term temporal scale (intra-annual). Analysis of all variables across all scales showed that no variable from one scale of observation was dominant, rather variables from multiple scales are contributing to hydrogeomorphic character to varying degrees.

Conclusions

This work demonstrates how an interdisciplinary, multi-scale approach is critical in detecting unique patterns in hydrogeomorphic character across different spatial and temporal scales. This approach enables a holistic view of spatio-temporal heterogeneity of a system and provides a firm basis for investigating how the physical template influences and helps to maintain patterns of biodiversity and ecosystem processes in complex and dynamics systems.

中文翻译：

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时空尺度在描述河流景观水文地貌特征中的重要性

语境

以整体方式描述河流的水文地貌特征对于理解淡水生态系统维持生物多样性和生态系统过程模式的过程至关重要。进行这种表征的一个关键问题是最能代表栖息地之间差异和相似性的时间和空间尺度。

目标

本研究的目的是在多个时空尺度上描述大型河流泛滥平原系统（美国密西西比河上游）的水文和地貌特征，以全面确定影响河流生态系统的物理模板。

方法

17 个变量用于描述沿河 100 公里范围内的 99 个回水和漫滩湖泊的水文地貌特征。

结果

在景观尺度（10 s 公里），景观中的位置和邻近栖息地的距离对水文地貌特征的变异性贡献最大。在较小的斑块尺度（10-100 秒的米），斑块的入口形状和水深是区分变量。就时间变量而言，栖息地的特征在于描述连接事件上升和下降的历史性质的年代际尺度变量，以及长期连接的平均峰值和持续时间。相比之下，单个连接事件的大小和持续时间的相互作用在短期时间尺度（年度内）产生了独特的模式。对所有尺度的所有变量的分析表明，没有一个观察尺度的变量占主导地位，

结论

这项工作证明了跨学科、多尺度的方法在检测不同空间和时间尺度上的水文地貌特征的独特模式方面是多么重要。这种方法可以全面了解系统的时空异质性，并为研究物理模板如何影响和帮助维护复杂动态系统中的生物多样性和生态系统过程的模式提供了坚实的基础。