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. 栖息地修复（habitat restoration）正日益被应用于退化溪流与河流，以期提升生物多样性与生态系统功能。过往针对生物多样性恢复效果的后续评估，往往鲜有证据表明生态系统得到恢复，这引发了学界对栖息地修复在提升生态完整性方面有效性的担忧。然而，诸如生态过程速率、生物群落功能性状组成等其他生态变量的响应特征，却极少被研究。 2. 本研究选取20处北方溪流河段作为研究对象，涵盖修复程度各异的位点、渠化河段以及天然参照河段，旨在探究栖息地异质性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的河流地貌量化指标之间的关联。 3. 叶片分解速率与栖息地异质性呈显著正相关，这一现象与食碎屑生物群落的功能组成变化密切相关：在栖息地异质性更高的河段，专性碎屑食者的占比显著更高。细颗粒有机物质沉积量在修复河段中始终高于渠化河段，且随异质性梯度升高而增加。单位面积藻类生物量累积量则既未随修复措施发生变化，也未随异质性梯度产生波动。 4. 总结与应用：本研究结果证实，河流栖息地异质性修复可增强有机质的留存与分解，这两项关键生态过程是支撑生态系统功能与生态系统服务供给的核心基础。值得关注的是，食碎屑生物群落的功能组成改变（而非物种多样性变化）与叶片分解速率提升存在关联。未来开展栖息地修复成效评估时，除了纳入河流地貌测量与传统生物指标外，还应量化生态过程与生物功能性状，从而实现对生态响应更全面、更具机制性的评估。