Dendrochronological methods for reconstructing mass movements — An example of landslide activity analysis using tree-ring eccentricity

Dendrochronological methods can be applied to the reconstruction of different types of environmental events such as climate changes, fires, glacier movements, floods, earthquakes, volcano activity. In the field of geomorphology dendrochronology is increasingly frequently used for the absolute dating of different types of mass-movements (rock falls, landslides and debris flows, etc.). Trees growing on slopes transformed by mass-movements are tilted and wounded while their stems and root systems are exposed or buried under sediment. These events are recorded in wood anatomy as eccentric growth, reaction wood, scar overgrowth by callous tissue, changes in cell size or adventitious root production. Dating changes in wood anatomy allows to date and precisely reconstruct the spatial and temporal occurrence of mass-movements with at least one year resolution. The paper provides a review of existing dendrochronological tools used in geomorphology and also an example of the application of eccentric tree-growth to reconstruct landsliding. Using tree-ring eccentricity allows to (1) obtain a dynamic depiction of slopes, (2) study landslide activity, not only contemporary, but also in the last tens of hundreds of years (depending on the stand age).     

Pious Way to Politics: The Rise of Political Salafism in Post‐Mubarak Egypt

The Arab Spring has reshaped the Islamist landscape in the Middle East drastically. After decades of repression and exclusion, Islamist parties have taken power in Egypt, Tunis, and Morocco. However, the startling rise of Salafism (Salafiyya) remains the most visible feature of the new Islamist scene in the region. After decades of eschewing politics for theological and political reasons, Salafi movements and groups have rushed into electoral politics enthusiastically. They became keen to form political parties, contest elections, and vie for power. In Egypt, the Salafi parties fared well in the post‐revolution parliamentary elections and are a key player in drafting Egypt's new constitution. This article explores the rise of Salafism after Mubarak and examines its effects on the democratic transition in Egypt. It investigates the ideological and theological stance of Salafi movements and parties on politics and democracy in particular. The argument put forward is that the extraordinary political openness in Egypt after the revolution has pushed Salafis into everyday politics. Subsequently, Salafis have become more inclined to adopt a pragmatic and practical discourse. Based on field research, this article provides a thematic analysis of Egyptian Salafism and assesses its political future.     

Human-planted alder trees as a protection against debris flows (a dendrochronological study from the Moxi Basin, Southwestern China)

Large debris flows have destroyed the infrastructure and caused the death of people living in the Moxi Basin (Sichuan Province, Southwestern China). Inhabitants of the Moxi Basin live on the flat surfaces of debris-flow fans, which are also attractive for farming. During the monsoon season debris flows are being formed above the fans. Debris flows can destroy the houses of any people living within the fan surfaces. In order to prevent the adverse effects of flows, people plant alder trees (Alnus nepalensis) at the mouths of debris flow gullies running above debris flow fans. Alders are able to capture the debris transported during flow events. Trees are well adapted to surviving in conditions of environmental stress connected with abrupt transport and deposition of sediment from debris flows. Numerous wounds, tilting and bending of alder trees caused by debris flows only very rarely cause the death of trees. By dating scars and dating the time of alder tilting (through the analysis of annual rings), we have determined the frequency of debris flows occurring at the mouth of the Daozhao valley. In 1980–2012 within the studied debris-flow fan and the Daozhao gully, 2 large debris flow events occurred (1996, 2005) and some smaller events were probably recorded every 2–3 years.