ABSTRACT

Fluvial dynamics are driven by multiple environmental factors and scales. Studies coupling hydrological and nutrient dynamics of mountain streams are almost non-existent in the Northern Patagonian region; which is characterised by a temperate-cold climate. We studied two adjacent streams with contrasting drainage basins: Casa de Piedra (41°07′30.11″S 71°27′13.16″W), which originates in a small mountain lake and runs through pristine landscapes, and Gutiérrez (41°09′36.18″S 71°24′37.19″W) that originates in a large piedmont lake and runs through an anthropized landscape. The streams displayed contrasting hydrological and nutrient dynamics. Casa de Piedra had higher discharge flashiness with shorter response delays to precipitation. Whereas the hydrology of Gutiérrez was buffered by the upstream lake, its nutrient exports were not. Differences observed in quality and timing in the export of coarse particulate organic matter and levels of phosphorus and nitrogen are explained by human activities affecting Gutiérrez but not Casa de Piedra. Moreover, the ratio of nitrogen:phosphorus suggests that phosphorus may be the limiting nutrient in the future, at the more densely populated basin. To summarise, Northern Patagonian streams flowing under marked geological and climate similarities, display stark differences in dynamics of their adjacent basins due to differences in topography and land use.

摘要

河流动力学受多种环境因素和尺度驱动。在巴塔哥尼亚北部地区，几乎不存在将山间溪流的水文和营养动态耦合起来的研究；其特点是温带寒冷气候。我们研究了两条具有对比鲜明流域的相邻溪流：Casa de Piedra（41°07′30.11″S 71°27′13.16″W），它起源于一个小山湖并​​贯穿原始景观，以及 Gutiérrez（41°09′） 36.18″S 71°24′37.19″W) 起源于一个大型山前湖，贯穿人类化的景观。溪流显示出对比鲜明的水文和营养动态。Casa de Piedra 具有更高的放电闪光度，对降水的响应延迟更短。虽然古铁雷斯的水文受到上游湖泊的缓冲，但其营养输出却没有。观察到的粗颗粒有机物出口质量和时间差异以及磷和氮水平的差异可以通过影响古铁雷斯但不影响 Casa de Piedra 的人类活动来解释。此外，氮：磷的比例表明，在人口更密集的盆地，磷可能是未来的限制性营养物质。总而言之，北巴塔哥尼亚河流在明显的地质和气候相似性下流动，由于地形和土地利用的差异，其相邻盆地的动态显示出明显的差异。磷表明，在人口更稠密的流域，磷可能是未来的限制性营养素。总而言之，北巴塔哥尼亚河流在明显的地质和气候相似性下流动，由于地形和土地利用的差异，其相邻盆地的动态显示出明显的差异。磷表明，在人口更稠密的流域，磷可能是未来的限制性营养素。总而言之，北巴塔哥尼亚河流在明显的地质和气候相似性下流动，由于地形和土地利用的差异，其相邻盆地的动态显示出明显的差异。