The Little Bow River (LBR) in western Canada naturally displayed an intermittent flow regime; the channel dried up most summers, excluding the development of riparian woodlands within this semi‐arid ecoregion. Around 1900, the Little Bow Canal was excavated to divert water from the adjacent Highwood River and with flow augmentation the LBR flow became continuous through the growth season. We hypothesized that the continuous regime enabled riparian woodland establishment and assessed conditions with sequential aerial photographs and field observations. Supporting the hypothesis, a few woodland groves established near the Highwood River where balsam poplars (Populus balsamifera) provided an abundant seed source. To investigate the basis for woodland development, we analysed historical hydrology of the LBR and assessed the four larger woodland groves, which included mature poplars, trembling aspen (P. tremuloides) and willow shrubs (Salix bebbiana and S. exigua). Each location had some bank excavation with channelization or gravel mining, and tree ageing through ring counts indicated gradual colonization and pulses of establishment after floods in 1920 and 1942. Thus, the conversion from an intermittent to continuous flow regime enabled woodland development which also benefited from excavations that created barren colonization sites. The study revealed four requirements for riparian woodland colonization in a dry region: (a) seeds, (b) barren sites, (c) bank saturation with higher river flow, and (d) sufficient river flows for tree and shrub survival and growth. While water withdrawal commonly degrades riverine ecosystems, flow augmentation can provide the opposite outcome, enhancing the river and riparian environments.

中文翻译：

---

漫滩森林的流量：从间歇性流量转换为连续流量使沿草原河的河岸林地发展

加拿大西部的小弓河（LBR）自然表现出间歇性的水流态势。整个夏季，河道干dried，不包括这个半干旱生态区的河岸林地。1900年左右，开挖了小弓运河，将附近的Highwood河中的水分流，随着流量的增加，LBR流量在整个生长季节变得连续。我们假设连续的制度使河岸林地得以建立并通过连续的航空照片和实地观察来评估条件。支持该假设的是，在海伍德河附近建立了一些林地，其中的香脂白杨（Populus balsamifera）提供了丰富的种子来源。为了探讨林地发展的基础，我们分析了LBR的历史水文和评估的四个较大的林地林，其中包括成熟的白杨，白杨颤抖（P，山杨）和柳树灌木（柳bebbiana和小号。夜蛾）。每个位置都有一些河道开挖和渠道化或砾石开采，并且通过环数的树木老化表明1920年和1942年洪水后逐渐的定殖和建立脉动。因此，从间歇性流向连续性流域的转换使得林地发展也从中受益开挖造成贫瘠的殖民地。该研究揭示了干旱地区河岸林地定植的四个要求：（a）种子，（b）贫瘠的土地，（c）河岸饱和度较高的河水，以及（d）足够的河水用于树木和灌木的生存和生长。虽然取水通常会使河流的生态系统退化，但增加流量可以提供相反的结果，从而改善了河流和河岸环境。