Recruitment limitation is known to influence species abundances and distributions. Recognition of how and why it occurs both in natural and in designed environments could improve restoration. Aquatic insects, for instance, rarely reestablish in restored streams to levels comparable to reference streams even years after restoration. We experimentally increased oviposition habitat in five out of 10 restored streams in western North Carolina to test whether insect egg-laying habitat was limiting insect populations in restored streams. A main goal was to test whether adding oviposition habitat in the form of rocks that partially protrude above the water surface could be used to increase the abundance and richness of stream insect eggs and larval insects in restored streams. Adding egg-laying habitat enhanced several response variables (e.g., protruding rocks, number of eggs, egg masses, egg morphotype richness, and oviposition habitat stability) to levels similar to those found in reference streams. Following the addition of protruding rocks, egg mass abundance increased by 186% and richness by 77% in restored-treated streams. Densities of larval insects that attached their eggs to protruding rocks showed an overall pattern consistent with treatment effects due to the combination of nonsignificant and significant increases of several taxa and not just one taxon. Our results indicate that these stream insect populations are limited by oviposition habitat and that adding egg-laying habitat alleviated this component of recruitment limitation. However, the weaker larval response indicates that additional post-recruitment factors, such as egg or larval mortality, may still be limiting a full recovery of larval insect abundances in these restored streams. This study shows the importance of integrating information from animal life histories, ecology, and geomorphology into restoration practices to improve the recovery of aquatic insects, which are commonly used to assess water quality and the biological efficacy of stream restoration.

中文翻译：

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通过增加产卵栖息地促进恢复河流中昆虫群落的恢复

众所周知，补充限制会影响物种的丰度和分布。认识到它在自然和设计环境中如何以及为何发生可以改善恢复。例如，即使在恢复多年后，水生昆虫也很少在恢复的溪流中重新繁殖到与参考溪流相当的水平。我们通过实验增加了北卡罗来纳州西部十分之五恢复的溪流的产卵栖息地，以测试昆虫产卵栖息地是否限制了恢复的溪流中的昆虫数量。主要目标是测试是否可以使用部分突出水面的岩石形式增加产卵栖息地，以增加恢复的溪流中溪流昆虫卵和幼虫昆虫的丰度和丰富度。添加产卵栖息地可增强多个响应变量（例如突出的岩石、卵数量、卵质量、卵形态类型丰富度和产卵栖息地稳定性），使其达到与参考溪流中相似的水平。添加突出岩石后，经过恢复处理的溪流中卵量丰度增加了 186%，丰富度增加了 77%。将卵附着在突出岩石上的幼虫昆虫的密度显示出与处理效果一致的总体模式，这是由于几个类群（而不仅仅是一个类群）的非显着和显着增加的组合。我们的结果表明，这些溪流昆虫种群受到产卵栖息地的限制，并且增加产卵栖息地减轻了补充限制的这一组成部分。然而，较弱的幼虫反应表明，额外的招募后因素，例如卵或幼虫死亡率，可能仍然限制这些恢复的溪流中幼虫昆虫丰度的全面恢复。这项研究表明，将动物生活史、生态学和地貌学信息整合到恢复实践中以改善水生昆虫的恢复非常重要，这些信息通常用于评估水质和溪流恢复的生物功效。