EGU General Assembly 2020
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What explains the elevational upward shifts at the treeline ecotone?

Àngela Manrique-Alba and Santiago Beguería
Àngela Manrique-Alba and Santiago Beguería
  • Consejo Superior Investigaciones Científicas, Estación Experimental Aula Dei, Zaragoza, Spain (

Temperatures have increased worldwide in the last decades, with the most pronounced and rapid changes occurring at high altitudes and latitudes. Climate change has played an important role in modifying the altitudinal location of the treeline ecotone, i.e. the transition from timber line (the upper forest limit, defined by the presence of a continuous forest cover) to the treeline (the last upright trees reaching 2 or 3 m in height). Moreover, the influence of recent land use change (e.g., changes in pastoral use, tourism development) in treeline dynamics is increasingly acknowledged. We have compiled a dataset of treeline changes over the Pyrenees mountain range, extending over more than 12000 linear kilometres, representing a large study area that extends across a broad range of environmental conditions. The main objective was to assess the effects of climate change, past land uses and physiography on the treeline dynamics between 1956 and 2015. To explore the variation in treeline shifts we used pairs of aerial photographs taken in 1956 and 2015 and we identified the position of the tree line using a criterion based on canopy cover thresholds. Our findings show significant differences between tree line dynamics for the two analysed periods and allow us to infer the relative importance of climatic factors, land use change, and local anthropogenic influence modulating the treeline structure and its dynamics.

How to cite: Manrique-Alba, À. and Beguería, S.: What explains the elevational upward shifts at the treeline ecotone?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9284,, 2020


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  • CC1: Comment on EGU2020-9284, Aditya Acharya, 08 May 2020

    Hello, and thank you first for this discussion forum.

    I am a Master second-year student at AgroParisTech University, France and I am doing exactly similar type of research for my thesis. I do not understand one physiographic variable that is analyzed here - the Convexity. I can understand the literal meaning of the term, but how is that measured or calculated? Could you please explain in short or suggest some resources that explain in a simple, understandable way (for a Masters student :) )

    Thank you so much for the consideration.


    Aditya ACHARYA

    • CC3: Reply to CC1, ÀNGELA MANRIQUE-ALBA, 12 May 2020


      I recommend you to have a look at SAGA gis, in which different algorithms are implemented to calculate convexity. There you have all the references that can help you.

  • CC2: Comment on EGU2020-9284, Cyrille Rathgeber, 12 May 2020

    Dear Angela,

    I was attending your chat last Friday and I really enjoyed it.
    I wanted to get in contact with you since we are conducting similar research on the Pyrenees.
    I tried to send an email to you using the address you gave at the end of your presentation, but it didn't work!
    Here is my email:
    Could you send me a message so we get in touch?
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displays version 1 – uploaded on 01 May 2020, no comments