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A new simple topo-climatic model to predict surface displacement in paraglacial and periglacial mountains of the European Alps: The importance of ground heating index and floristic components as ecological indicators
Ecological Indicators ( IF 7.0 ) Pub Date : 2020-09-09 , DOI: 10.1016/j.ecolind.2020.106889
Ponti Stefano , Cannone Nicoletta , Guglielmin Mauro

Landscape evolution is occurring at rapid rates in alpine areas in response to recent climate warming, also due to the susceptibility and the heterogeneity of these environments. Here we present a prediction model of surface displacements that takes into account both topographic and climatic variables. Observed points of surficial displacements have been associated to non-climatic (altitude, slope, solar radiation, till deposit type, deposit age, vegetation coverage) and climatic (days of snow permanence, ground surface temperature index, ground heating index, ground cooling index) variables through a general regression model in the European central Alps.

The model output shows the importance of slope and ground heating index (GHI) – an estimation of the amount of energy transferred to the ground, to predict surface displacements independently from the type of considered processes. In particular, the general regression model shows that steep zones with high GHI are more susceptible to undergo periglacial and paraglacial processes producing surface displacements. As expected, slope is fundamental to trigger processes such as gravitation, nivation, solifluction and their interactions. The results of our model emphasize the key role of GHI, highlighting the importance of climate in controlling the surface displacement. Indeed, in areas in which GHI is higher, the ground can remain snow free for a longer time and snow melting can be faster, the former favoring more runoff and slopewash, and the latter promoting the saturation of the deposits consequent to a higher intensity of solifluction and/or mass movements processes.

Within the study area, the sites with the largest displacements (>35 cm) were detected where permafrost degradation occurred since 1990. This permafrost degradation process could remain one of the main triggering factors of future surface displacements. Our results confirm that when movement involves material with coarse texture (pebbles and boulders) exceeding the rooting depth, only tolerant plant species can withstand the high movement rates. The areas where this can happen (like rock glaciers or screes) act as a physical barrier to grasslands species not adapted to surface displacements and trying to shift towards higher altitude in response to climate warming. However, plant species not considered as indicators of movement (such as graminoids), can develop also with large surface displacements in specific geomorphic conditions. Therefore, the combination of surface displacement type (deep vs surficial), material texture (fine vs coarse) and vegetation cover (high vs low) and floristic composition can be used as a valuable ecological indicator of movement.

Our results suggest that both landscape degradation and vegetation displacement can be rapid especially where the air warming was strong as in the selected study area.



中文翻译:

一个新的简单的地形气候模型,可以预测欧洲阿尔卑斯山的冰山和冰缘山地表位移:地热指数和植物区系作为生态指标的重要性

响应于最近的气候变暖,高山地区的景观演变正在迅速发生,这也是由于这些环境的敏感性和异质性。在这里,我们提出了一种考虑了地形和气候变量的地表位移预测模型。观测到的表面位移与非气候(海拔,坡度,太阳辐射,直到沉积物类型,沉积物年龄,植被覆盖率)和气候(降雪天数,地表温度指数,地面加热指数,地面冷却指数)相关。 )变量通过欧洲中部阿尔卑斯山的一般回归模型得出。

模型输出显示了坡度和地面加热指数(GHI)的重要性-估计传递到地面的能量,以独立于所考虑的过程类型来预测表面位移。特别是,一般回归模型显示,具有高GHI的陡峭区域更容易经历冰缘和冰缘下过程,产生表面位移。不出所料,坡度是引发重力,引力,固溶作用及其相互作用等过程的基础。我们模型的结果强调了GHI的关键作用,强调了气候在控制地表位移中的重要性。实际上,在GHI较高的地区,地面可以长时间保持无雪状态,融雪速度可以更快,前者则倾向于增加径流和冲刷,

在研究区域内,自1990年以来就发现了永久冻土退化发生的最大位移(> 35厘米)的地点。这种永久冻土退化的过程可能仍然是未来地表位移的主要触发因素之一。我们的结果证实,当运动涉及质地较粗(卵石和巨石)超过生根深度的材料时,只有耐性植物才能承受高运动速率。可能发生这种情况的区域(例如岩石冰川或熨平板)对不适应地表位移并试图响应气候变暖而向更高海拔转移的草原物种起到了物理屏障的作用。但是,在特定的地貌条件下,如果表层位移较大,则不被视为运动指标的植物物种(如类蠕虫)也会发展。因此,

我们的结果表明,景观退化和植被迁移都可能很快,尤其是在所选研究区域的空气变暖强烈的地方。

更新日期:2020-09-10
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