Assessing the effects of EXtreme summer flooding on STREAM ecosystem successional processes (EXSTREAM).

影响河流生态系统的一个主要变量是干扰，特别是洪水造成的干扰。洪水维持生态系统的多样性，并重新分配河流中的能量、营养物质、沉积物和生物群。河流的生物群（如无脊椎动物和鱼类）可以通过抵抗干扰（抵抗力）或快速恢复（复原力）在洪水中生存下来。虽然干扰河流生态系统，由于洪水已经比较好的研究，许多研究有一个有限的干扰前一系列的数据，对洪水的影响进行评估，很少在其演替发展方面，很少有比较不同的洪水制度。这在一定程度上反映了最低限度的连续，每年对溪流群落的监测，以衡量任何干扰effects.In冰川湾国家公园在阿拉斯加东南部，我们持有长期连续的数据集（长达35年的一些流），详细说明冰川退缩后的溪流群落演变。这些数据为河流无脊椎动物和鱼类的初级演替（随时间的变化）提供了独特的见解。对于一个流（狼点溪，WPC）的社区变化的一个非常详细的轨迹已组装自1977年以来，显示流已从一个占主导地位的几个种类的摇蚊（非叮咬蠓），最近包含一个多样化的社区的无脊椎动物（昆虫/非昆虫）和少年鲑鱼。2014年夏天，冰川湾和阿拉斯加东南部普遍出现了破纪录的长时间高降雨量，6月的降雨量是有记录以来最多的（189毫米=比正常高出231%）。此外，7月的降水量为211毫米，比正常多180%，是有记录以来第二多雨的7月。7月12日，冰川湾降雨量超过50毫米，4天内降雨量超过90毫米。强降水一直持续到8月，12日是有记录以来最潮湿的一天。这造成了一系列大的，经常性的和非典型的洪水事件在夏季（一些事件8倍的中位数流量），我们建议详细调查的影响。研究的三个主要途径将遵循：（1）洪水对不同年龄溪流生境和形态的影响;（2）洪水对原生演替框架影响的调查（无脊椎动物，鱼类）在狼点溪，以及（3）调查水浸对不同年代溪流的影响，以提供资料，说明处于不同演变阶段的溪流我们会将所得结果与2005年11月在同一系统内，但受持续强降雨（在少于72小时内超过650毫米）驱动的一次大规模洪水扰动所得结果作比较。与920毫米的平均年降雨量相比，上次事件的规模显而易见。这项研究将提供一个独特的研究，比较不同的洪水制度在不同的时间，一年中的地貌和生物的反应。随着气候变化，这些极端洪水事件预计将在未来变得更加普遍，因此我们的研究结果将为缓解策略提供信息，以管理洪水对生态系统完整性的影响。

A major variable influencing river ecosystems is disturbance, particularly that due to flooding. Floods maintain ecosystem diversity and redistribute energy, nutrients, sediment and biota in rivers. The biota of rivers (e.g. invertebrates and fish) may survive floods either by withstanding the disturbance (resistance) or recovering rapidly (resilience). Although disturbance to river ecosystems due to flooding has been relatively well studied, many studies have a restricted pre-disturbance series of data against which to evaluate flood effects and rarely in terms of their successional development and few have compared different flooding regimes. This in part reflects minimal continuous, year-on-year monitoring of stream communities against which to measure any disturbance effects.In Glacier Bay National Park in southeast Alaska, we hold long-term continuous data sets (up to 35 years for some streams) detailing stream community evolution following glacial retreat. These data have provided unique insights into primary succession (change over time) of stream invertebrates and fish. For one stream (Wolf Point Creek; WPC) a highly detailed trajectory of community change has been assembled since 1977, showing how the stream has evolved from one dominated by a few species of Chironomidae (non-biting midges) to one more recently containing a diverse community of invertebrates (insects/non-insects) and juvenile salmonids. The summer of 2014 has seen record-breaking prolonged high rainfall in Glacier Bay and southeast Alaska generally, with the wettest June on record (189mm = 231% higher than normal). Furthermore, in July precipitation was 180% greater than normal with 211mm, making it the second wettest July on record. Over 50 mm rain fell in Glacier Bay on July 12 and > 90 mm in a 4-day period. Heavy precipitation has continued into August with the 12th being the wettest August day on record. This has created a series of large, recurrent and atypical flood events during the summer (some events 8x median flow), the effects of which we propose to investigate in detail. Three major avenues of research will be followed: (1) the effect of the flooding on the stream habitat and morphology across streams of different ages, (2) an investigation of the effect of the flooding on the primary successional framework (invertebrates, fish) in Wolf Point Creek, and (3) an investigation into the effects of the flooding on streams of different ages to provide information on how streams at different stages of successional development respond to flooding.We will compare the results with those obtained from one massive flood disturbance in November 2005 in the same system but driven by continuous heavy rainfall (over 650mm in less than 72 hours). The size of this previous event is evident when compared against an average annual rainfall of 920mm. This research will provide a unique study in comparison of different flooding regimes at different times of the year with respect to geomorphological and biotic responses. These extreme flooding events are expected to become more common in the future with climate change, thus our findings will inform mitigation strategies to manage the effects of flooding on ecosystem integrity.