Aims

The stability of hillslopes is an essential ecosystem service, especially in alpine regions with soils prone to erosion. One key variable controlling hillslope stability is soil aggregate stability. We aimed at identifying dominant controls of vegetation parameters on aggregate stability and analysed their importance for soil aggregate stability during landscape development.

Methods

We quantified the aggregate stability coefficient (ASC) and measured plant cover, diversity, root mass and root length, density (RMD, RLD) along two chronosequences with contrasting bedrocks (siliceous, calcareous) in the Swiss Alps.

Results

We found that ASC developed slower along the calcareous chronosequence. Furthermore, we observed a significant positive effect of vegetation cover and diversity on ASC that was mediated via root density. These relationships developed in a time-depended manner: At young terrain ages, vegetation parameters had a strong effect on aggregate stability compared to older stages. Moreover, RLD was the most powerful predictor of ASC on young terrain, whereas on older moraines RMD became more important.

Conclusions

We highlight that root density plays a major role in governing ASC for soils differing in moraine ages. The changing importances of RLD and RMD for ASC development suggest different mechanistic linkages between vegetation and hillsope stability during landscape development.

中文翻译：

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根密度驱动瑞士阿尔卑斯山不同冰碛年龄土壤的团聚体稳定性

宗旨

山坡的稳定性是必不可少的生态系统服务，尤其是在土壤易受侵蚀的高山地区。控制山坡稳定性的一个关键变量是土壤团聚体稳定性。我们旨在确定植被参数对团聚体稳定性的主要控制，并分析它们在景观开发过程中对土壤团聚体稳定性的重要性。

方法

我们量化了总体稳定性系数 (ASC) 并测量了植物覆盖率、多样性、根质量和根长、密度（RMD、RLD），沿着两个具有对比性的瑞士阿尔卑斯山基岩（硅质、钙质）的时间序列。

结果

我们发现 ASC 沿钙质时间序列发展较慢。此外，我们观察到植被覆盖和多样性对 ASC 的显着积极影响，这是通过根密度介导的。这些关系以时间依赖的方式发展：在年轻的地形年龄，与较老的阶段相比，植被参数对总体稳定性有很大的影响。此外，RLD 是年轻地形上 ASC 最有力的预测因子，而在较老的冰碛上，RMD 变得更加重要。

结论

我们强调根密度在管理不同冰碛年龄的土壤的 ASC 方面起着重要作用。RLD 和 RMD 对 ASC 开发的重要性不断变化表明在景观开发过程中植被和山坡稳定性之间存在不同的机械联系。