Headwater Habitat Streams in Central Massachusetts 2002-2005

Headwater streams, particularly those that flow only during part of the year, are understudied and underprotected in Massachusetts. Research being conducted elsewhere suggests that these "Headwater Habitat Streams" are important both for aquatic biodiversity and for ecological function of lower stream reaches. We are carrying out baseline research, involving research scientists and volunteers, on hydrology and habitat characteristics in headwater streams in northern Worcester County, MA. We hypothesized that headwater streams exhibit a longitudinal gradient of hydrology, from (1) ephemeral channels that flow only in response to storms, through (2) intermittent sections that flow seasonally until the groundwater table falls below the channel and are dry the rest of the year, to (3) interstitial reaches that flow seasonally and retain pools connected by subsurface flow during the summer, to (4) the perennial stream. Results to date show a high degree of longitudinal heterogeneity in the study streams, with interspersion of perennially flowing reaches among low-gradient sections of vegetated wetland, high-gradient boulder piles, and braided channels. Perennial flow is found high up in some watersheds. We expect our methods and results will have implications throughout the Commonwealth for local conservation commissions and other municipal officials responsible for land-use planning and regulation, state agencies responsible for land management and the protection of wildlife, regulators reviewing projects affecting streams, watershed managers, teachers and their students, private land trusts, conservation advocates, and citizen-naturalists.马萨诸塞州（Massachusetts）境内的源头溪流（Headwater Streams），尤其是仅季节性径流的河段，长期以来研究不足且保护力度薄弱。其他地区开展的相关研究表明，这类源头生境溪流（Headwater Habitat Streams）对水生生物多样性以及下游河段的生态功能均具有重要意义。本研究针对马萨诸塞州伍斯特县（Worcester County）北部的源头溪流展开水文与生境特征的基线研究，研究团队涵盖科研人员与志愿者。我们提出如下假说：源头溪流的水文特征呈现纵向梯度变化，依次为（1）仅在暴雨后产生径流的暂时性河道（ephemeral channels）；（2）季节性径流的间歇河段（intermittent sections）——即径流持续至地下水位降至河床以下，其余时段完全干涸；（3）季节性径流的潜流河段（interstitial reaches）——夏季时仍保留由地下径流连通的水潭；最终过渡至（4）常年性溪流（perennial stream）。截至目前的研究结果显示，本研究涉及的溪流存在显著的纵向异质性，常年径流河段穿插分布于植被覆盖的湿地缓坡段、高梯度砾石滩以及辫状河道之中。部分流域的上游区域也存在常年径流河段。我们预计，本研究的方法与成果将对整个马萨诸塞联邦产生广泛应用价值，服务对象包括负责土地利用规划与监管的地方保护委员会及其他市政官员、负责土地管理与野生动物保护的州级机构、审查涉溪项目的监管人员、流域管理者、师生群体、私人土地信托机构、自然保护倡导者以及公民自然学家。