Data from: Enhanced ecosystem functioning following stream restoration: the roles of habitat heterogeneity and invertebrate species traits

1. Habitat restoration is increasingly undertaken in degraded streams and rivers to help improve biodiversity and ecosystem functioning. Follow-up assessments focused on outcomes for biodiversity have often found scant evidence for recovery, thus raising concerns about the efficacy of habitat restoration for improving ecological integrity. However, responses of other ecological variables, such as ecosystem process rates and the functional trait composition of biological assemblages, have been little assessed. 2. We assessed how the restoration of habitat heterogeneity affected multiple functional parameters in 20 boreal stream reaches encompassing both more and less extensively restored sites, as well as channelised and natural reference sites. We further assessed relationships between our parameters and a fluvial geomorphic measure of habitat heterogeneity. 3. Leaf decomposition was positively related to habitat heterogeneity. This was associated with shifts in the functional composition of detritivore assemblages, with the most obligate litter consumers more prominent in reaches showing higher habitat heterogeneity. The deposition of fine particulate organic matter was consistently higher in restored than channelised sites, and was positively related to the heterogeneity gradient. Algal biomass accrual per unit area did not vary either with restoration or the heterogeneity gradient. 4. Synthesis and applications: Our findings demonstrate that restoration of river habitat heterogeneity can enhance retention and decomposition of organic matter, key ecosystem processes underpinning ecosystem functioning and service delivery. Significantly, enhanced litter decomposition was linked with a change in the functional composition rather than diversity of detritivore assemblages. Future evaluation of the success of habitat restorations should incorporate quantification of ecosystem processes and the functional traits of biota, in addition to measures of fluvial geomorphology and the more traditional biotic metrics, to facilitate a more comprehensive and mechanistic assessment of ecological responses.1. 针对受损溪流与河流的栖息地修复（habitat restoration）工作正日益增多，旨在改善生物多样性与生态系统功能。以往聚焦生物多样性恢复成效的后续评估，往往难以找到足够的恢复证据，由此引发了人们对栖息地修复在提升生态完整性方面有效性的担忧。然而，诸如生态系统过程速率、生物群落功能性状组成等其他生态变量的响应，却极少得到评估。2. 本研究针对20处北方河流河段（涵盖修复程度不同的样点、渠化样点与自然对照样点），评估了栖息地异质性（habitat heterogeneity）修复对多项功能参数的影响；同时进一步分析了这些功能参数与栖息地异质性河流地貌度量指标之间的关联。3. 叶片分解（leaf decomposition）速率与栖息地异质性呈正相关。这一现象与食碎屑生物（detritivore）群落的功能组成变化有关：在栖息地异质性更高的河段，专性枯食消费者的丰度更高。细颗粒有机物质（fine particulate organic matter）的沉积量在修复样点中始终高于渠化样点，且与异质性梯度呈正相关。单位面积藻类生物量累积量则未随修复措施或异质性梯度发生显著变化。4. 综合与应用：本研究结果表明，河流栖息地异质性修复可提升有机物质的留存与分解效率——这是支撑生态系统功能与服务供给的关键生态过程。值得注意的是，枯落物分解速率的提升与食碎屑生物群落的功能组成变化相关，而非与其多样性有关。未来开展栖息地修复成效评估时，除了河流地貌测量与传统生物指标外，还应纳入生态系统过程量化与生物功能性状测定环节，从而实现对生态响应更全面、更具机制性的评估。