Effect of tree thinning and skidding trails on hydrological connectivity in two Japanese forest catchments
Effect of tree thinning and skidding trails on hydrological connectivity in two Japanese forest catchments
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DOI：
10.1016/j.geomorph.2017.05.006
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发表时间：
2017-09
期刊：
影响因子：
3.9
通讯作者：
M. López‐Vicente;Xinchao Sun;Y. Onda;H. Kato;T. Gomi;M. Hiraoka
中科院分区：
文献类型：
--
作者：
M. López‐Vicente;Xinchao Sun;Y. Onda;H. Kato;T. Gomi;M. Hiraoka
土地利用组成和模式影响山区和森林流域的水文响应。在人工林中，管理作业（FMO）改变了地表径流过程的空间和时间动态。然而，我们发现在不同 FMO 下人工林水文连通性 (HC) 建模方面的文献存在空白。在这项研究中，我们模拟了两个陡峭的配对森林子流域（K2 和 K3，33.2 公顷）的 HC，这些子流域由日本柏树 (Chamaecyparis obtusaEndl.) 和日本雪松 (Cryptomeria japonicaD. Don) 人工林（占总面积的 59%）组成，不同时间的树木间伐强度为 50%。此外，在为期 40 个月的测试期（2010 年 7 月至 2013 年 10 月）的五种基于间伐的情景中模拟了新集材道的建设和植被恢复。作为未来的设想，建议在干流中修建六个拦河坝，以减少沉积物和放射性核素的输送。使用 D-无穷大流量累积算法并利用三个 0.5 米分辨率的数字高程模型，运行了 Borselli 径流和沉积物连通性指数的更新版本。根据 FMO 之前的情景，由于树木稀疏和新的集材路径，HC 在流域范围内增加。这一变化在受 FMO 影响的地区更为明显，K2 的柏树和雪松人工林的 HC 分别增加了 11.4% 和 10.5%，K3 的雪松人工林的 HC 增加了 8.8%。在山坡图和河流尺度上，HC 值的演变不太明显，除了 FMO 之后在 K2 处的河流中观察到的增量（5.4%）。 FMO 后植被逐渐恢复，导致两个子流域所有分区的连通性略有下降。森林道路，尤其是集材小径呈现出最高的 HC 值，似乎是连接不同植被斑块与河流网络的最有效特征。过去五种情景中 HC 的空间和时间演变与观测到的产流变化以及 FMO 之前、期间和之后降雨拦截和径流的可用值密切相关。对拟议情景的模拟建议修建淤地坝作为有效的景观特征，以在一定程度上减少碳氢化合物，从而减少两个子流域的沉积物和放射性核素输送率。
Land use composition and patterns influence the hydrological response in mountainous and forest catchments. In plantation forest, management operations (FMO) modify the spatial and temporal dynamics of overland flow processes. However, we found a gap in the literature focussed on modelling hydrological connectivity (HC) in plantation forest under different FMO. In this study, we simulated HC in two steep paired forest subcatchments (K2 and K3, 33.2 ha), composed of Japanese cypress (Chamaecyparis obtusaEndl.) and Japanese cedar (Cryptomeria japonicaD. Don) plantations (59% of the total area) against a tree thinning intensity of 50% at different time. Additionally, construction of new skidding trails and vegetation recovery was simulated on five thinning-based scenarios that covered a 40-month test period (July 2010 – October 2013). As a future scenario, six check-dams located in the main streams were proposed to reduce sediment and radionuclide delivery. An updated version of Borselli's index of runoff and sediment connectivity was run, using the D-infinity flow accumulation algorithm and exploiting three 0.5-m resolution digital elevation models. On the basis of the pre-FMO scenario, HC increased at catchment scale owing to tree thinning and the new skidding trails. This change was more noticeable within the area affected by the FMO, where HC increased by 11.4% and 10.5% in the cypress and cedar plantations in K2 respectively and by 8.8% in the cedar plantation in K3. At hillslope plot and stream scales, the evolution in the values of HC was less evident, except the increment (by 5.4%) observed in the streams at K2 after the FMO. Progressive vegetation recovery after the FMO triggered a slight reduction of connectivity in all compartments of both subcatchments. Forest roads and especially skidding trails presented the highest values of HC, appearing as the most efficient features connecting the different vegetation patches with the stream network. The spatial and temporal evolution of HC over the five past scenarios correlated well with the observed changes in runoff yield, as well as with the available values of rainfall interception and throughfall before, during, and after the FMO. The simulation of the proposed scenario recommends the construction of check-dams as effective landscape features to somewhat reduce HC and thus to decrease the sediment and radionuclide delivery rates from the two subcatchments.