By: Maaike Bader, November 10, 2020
Examples of treeline forms as described in the new Ecography paper. From left to right and top to bottom: gradual treeline, diffuse treeline, abrupt tree-island treeline, abrupt treeline, abrupt diffuse treeline in shrub matrix, krummholz-island treeline. From Bader et al, early view.
We are very happy to announce the publication of our new paper (open access in Ecography, for download here) addressing the pattern dimensions that we think are most indicative of the processes forming spatial patterns in alpine-treeline ecotones, and redefining some terminology for describing treeline spatial pattern or "form". This paper is the culmination of our discussions during several workshops in the past years, starting with the MRI synthesis workshop in Jaca, Spain, in 2017, followed by the two sTreelines workshops at sDiv (iDiv, Leipzig, Germany) in 2018 and 2019 and a workshop organised by Bradley Case in Hanmer Springs, New Zealand, in 2020.
Apart from defining four main pattern dimensions (two in the x-y plane: 1) changes in tree cover, and 2) changes in the level of clumping; two in cross-section: 3) changes in tree height, and 4) changes in tree shape), we here also suggest a more precise terminology for describing treeline forms. In particular, we suggest to use two different terms for describing the smoothness of the transition: if there is a sudden strong frop in tree HEIGHT the treeline is "abrupt", but if only the decrease in tree COVER is sudden and strong, this treeline is "discrete". If both change suddenly and strongly, the treeline is still "abrupt", because we consider discreteness as the default. At the other end, if tree HEIGHT decreases gradually, the treeline is "gradual", but if tree COVER decreases gradually, the treeline is "diffuse". If both decrease gradually, the treeline is still "diffuse", because we consider a gradual height decline as the default. Now one can guess what an abrupt diffuse treeline looks like... Additionally, there are tree-island and krummholz-island treelines and some other forms... I recommend reading the paper for more details and further insights :-)
You may also check out our blogpost on the Ecography website.
An abrupt (and discrete, which is the default so it does not need to be mentioned) treeline formed by Lophozonia menziesii (Nothofagaceae) near Lewis´ Pass on the South Island of New Zealand.
Reference: Bader, M.Y., L.D. Llambí, B.S. Case, H.L. Buckley, J.M. Toivonen, J.J. Camarero, D.M. Cairns, C.D. Brown, T. Wiegand and L.M. Resler (early view) A global framework for linking alpine-treeline ecotone patterns to underlying processes. Ecography, DOI 10.1111/ecog.05285.Back to top