智利海岸山脉的外来植树造林:平衡离散干扰、连通性和持续干旱对集水区侵蚀的影响

IF 2.8 2区 地球科学 Q2 GEOGRAPHY, PHYSICAL
Violeta Tolorza, Christian H. Mohr, Mauricio Zambrano-Bigiarini, Benjamín Sotomayor, Dagoberto Poblete-Caballero, Sebastien Carretier, Mauricio Galleguillos, Oscar Seguel
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引用次数: 0

摘要

摘要智利海岸山脉位于智利的地中海地区,是一片土壤覆盖的地貌,具有储存宝贵的淡水资源和支持生物多样性的本地森林的潜力。然而,在过去的 200 多年里,人类的干预加剧了土壤侵蚀,在过去的 45 年里,外来树木种植园的密集管理更是达到了顶峰。与此同时,这一地貌还受到了长期特大干旱的严重影响。因此,这些压力因素的结合使得在流域尺度上厘清人为干扰和水文气候趋势对沉积物通量的影响变得更加复杂。在这项研究中,我们根据悬浮物载荷计算出了十年一度的集水区侵蚀率,并将其与根据 10Be 碎片估算出的千年一度的集水区剥蚀率进行了比较。然后,我们将这两种速率与离散的人为干扰事件和水文气候趋势的影响进行对比。在十年和千年时间尺度上,侵蚀和剥蚀速率的大小相似,即分别为 0.018 ± 0.005 和 0.024 ± 0.004 毫米/年-1。近期的人为干扰包括四季伐木作业和密集的林道网络,从而增加了结构沉积物的连通性。其他干扰还包括两次大范围野火(2015 年和 2017 年)以及 2010 年发生的一次 Mw 值为 8.8 的地震。我们观察到,1986 年至 2018 年期间,雨季的悬浮泥沙负荷有所下降,这与溪流、基流和降雨量的下降相吻合。较低的千年侵蚀率与以缓慢扩散的土壤蠕动为主的地貌相吻合。然而,低十年侵蚀率和悬浮沉积物的减少与强烈人为干扰和结构(沉积物)连通性增加的预期效果不符。这种自相矛盾的现象表明,悬浮泥沙负荷以及相应的集水侵蚀作用被低估了,而且降雨量和溪流的减少(即水文气候驱动力减弱)掩盖了十年期泥沙剥离和迁移的作用。我们的研究结果表明,人为干扰和水文趋势可能会对近期侵蚀产生相反的、部分抵消的影响,但两者都会导致地貌退化。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Exotic tree plantations in the Chilean Coastal Range: balancing the effects of discrete disturbances, connectivity, and a persistent drought on catchment erosion
Abstract. The Chilean Coastal Range, located in the Mediterranean segment of Chile, is a soil-mantled landscape with the potential to store valuable freshwater supplies and support a biodiverse native forest. Nevertheless, human intervention has been increasing soil erosion for ∼ 200 years, culminating in the intense management of exotic tree plantations throughout the last ∼ 45 years. At the same time, this landscape has been severely affected by a prolonged megadrought. As a result, this combination of stressors complicates disentangling the effects of anthropogenic disturbances and hydroclimatic trends on sediment fluxes at the catchment scale. In this study, we calculate decennial catchment erosion rates from suspended-sediment loads and compare them with a millennial catchment denudation rate estimated from detrital 10Be. We then contrast both of these rates with the effects of discrete anthropogenic-disturbance events and hydroclimatic trends. Erosion and denudation rates are similar in magnitude on decennial and millennial timescales, i.e., 0.018 ± 0.005 and 0.024 ± 0.004 mm yr−1, respectively. Recent human-made disturbances include logging operations throughout all seasons and a dense network of forestry roads, thereby increasing structural sediment connectivity. Further disturbances include two widespread wildfires (2015 and 2017) and an earthquake with an Mw value of 8.8 in 2010. We observe decreased suspended-sediment loads during the wet seasons for the period 1986–2018, coinciding with declining streamflow, baseflow, and rainfall. The low millennial denudation rate aligns with a landscape dominated by slow diffusive soil creep. However, the low decennial erosion rate and the decrease in suspended sediment disagree with the expected effect of intense anthropogenic disturbances and increased structural (sediment) connectivity. Such a paradox suggests that suspended-sediment loads, and thus respective catchment erosion, are underestimated and that decennial sediment detachment and transport have been masked by decreasing rainfall and streamflow (i.e., weakened hydroclimatic drivers). Our findings indicate that human-made disturbances and hydrologic trends may result in opposite, partially offsetting effects on recent erosion, yet both contribute to landscape degradation.
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来源期刊
Earth Surface Dynamics
Earth Surface Dynamics GEOGRAPHY, PHYSICALGEOSCIENCES, MULTIDISCI-GEOSCIENCES, MULTIDISCIPLINARY
CiteScore
5.40
自引率
5.90%
发文量
56
审稿时长
20 weeks
期刊介绍: Earth Surface Dynamics (ESurf) is an international scientific journal dedicated to the publication and discussion of high-quality research on the physical, chemical, and biological processes shaping Earth''s surface and their interactions on all scales.
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