ABSTRACT The planting of degraded land with tree plantations may be effective at improving land use sustainability and profitability but it can also have significant effects on stream hydrology. In this paired catchment study, we report the stream hydrological response to partial (62%) afforestation of a steep pastoral catchment in the western Waikato Region, North Island, New Zealand. We comprehensively analyse the hydrological regime changes over a 23-year period (including eight years before pine planting) with reference to a native-forested ‘control’ catchment. Our results show that afforestation has markedly affected stream hydrology. Seven years after planting, the total annual runoff was 380 mm lower than predicted for the catchment in pasture. Two phases of plantation thinning resulted in the difference between measured and predicted runoff reducing to only 129 mm. Peak flows reduced by ∼50% while total stormflow reduced by ∼30% – which we attribute to canopy interception attenuating and delaying water yield. The impact of plantation establishment on low flows is not so clear, although afforestation appears to have reduced low flows by ∼25%. This study provides information on the hydrological impact of afforestation within a hitherto poorly-represented New Zealand environment (i.e. high rainfall, sedimentary lithology-based, North Island hill country).

中文翻译：

---

源头牧场集水区改建辐射松人工林的河流水文响应

摘要 在退化土地上种植人工林可能有效提高土地利用的可持续性和盈利能力，但也可能对河流水文产生重大影响。在这项配对集水区研究中，我们报告了新西兰北岛怀卡托地区西部陡峭牧区集水区部分 (62%) 植树造林的河流水文响应。我们综合分析了 23 年期间（包括松树种植前 8 年）的水文情势变化，并参考了原生林“对照”集水区。我们的结果表明，植树造林显着影响了河流水文。种植 7 年后，每年总径流比对牧场集水区的预测低 380 毫米。人工林间伐的两个阶段导致实测和预测径流之间的差异减少到仅 129 毫米。峰值流量减少了约 50%，而总暴雨流量减少了约 30%——我们将其归因于冠层拦截减弱和延迟了出水量。人工林建立对低流量的影响并不那么明显，尽管植树造林似乎将低流量减少了约 25%。这项研究提供了在迄今为止代表性较差的新西兰环境（即高降雨量、基于沉积岩性的北岛山区）内造林对水文影响的信息。人工林建立对低流量的影响并不那么明显，尽管植树造林似乎将低流量减少了约 25%。这项研究提供了在迄今为止代表性较差的新西兰环境（即高降雨量、基于沉积岩性的北岛山区）内造林对水文影响的信息。人工林建立对低流量的影响并不那么明显，尽管植树造林似乎将低流量减少了约 25%。这项研究提供了在迄今为止代表性较差的新西兰环境（即高降雨量、基于沉积岩性的北岛山区）内造林对水文影响的信息。