Ordonez, A. C. | bioRxiv Science

bioRxiv2023

Short-term thinning effect on inter- and intra-annual radial increment of Mediterranean Scots pine-oak mixed forest

Thinning treatment and mixed forest stands have been suggested as possible adaptation strategies to cope to climate change but there is still scarce knowledge about the combination of both subjects. In this study, we aim to better understand the thinning effect and the growth differences between two coexisting species on inter- and intra-annual cumulative radial increment patterns. We studied radial increment of a Scots pine-oak (Pinus sylvestris-Quercus pyrenaica) Mediterranean mixed forest during two climatically contrasted years (2016-2017) in north-western Spain. Data came from a thinning trial consisting in a randomized block experimental design with a control and two thinning treatments from below: a moderate and heavy thinning removing 25% and 50 % of initial basal area respectively focused on both species. Tree radial increment was analyzed based on bi-weekly readings from band dendrometers installed in 90 oak and pine trees. Non-linear mixed model based on double-Richards curve was fitted to show thinning and species differences in intra-annual cumulative radial increment patterns. Inter-annual basal area increment at species and stand levels were estimated using the model previously fitted at tree level and aggregating the results for exploring thinning effects at these levels. Scots pine leaded the tree and stand growth, and had also a better respond to early spring drought compared to oak. Heavy thinning increased tree radial increment for both species at the expense of decreased stand basal area. At species level, basal area increment decreased for Scots pine, however, heavy thinning generated the same oak basal area increment than control. Thus, heavy thinning may be good strategy towards a conversion from overaged coppice stands into high forests to conform a stable mixed forest stand. HighlightsO_LIScots pine leaded growth at tree and stand level C_LIO_LIScots pine trees may take advantage during early spring droughts C_LIO_LIHeavy thinning increased tree radial increment for both species C_LIO_LIHeavy thinning decreases stand basal area growth C_LI

ecology↗

bioRxiv2018

Mitogenomes illuminate the origin and migration patterns of the indigenous people of the Canary Islands

The Canary Islands indigenous people have been the subject of substantial archaeological, anthropological, linguistic and genetic research pointing to a most probable North African Berber source. However, neither agreement about the exact point of origin nor a model for the indigenous colonization of the islands has been established. To shed light on these questions, we analyzed 48 ancient mitogenomes from 25 archaeological sites from the seven main islands. Most lineages observed in the ancient samples have a Mediterranean distribution, and belong to lineages associated with the Neolithic expansion in the Near East and Europe (T2c, J2a, X3a...). This phylogeographic analysis of Canarian indigenous mitogenomes, the first of its kind, shows that some lineages are restricted to Central North Africa (H1cf, J2a2d and T2c1d3), while others have a wider distribution, including both West and Central North Africa, and, in some cases, Europe and the Near East (U6a1a1, U6a7a1, U6b, X3a, U6c1). In addition, we identify four new Canarian-specific lineages (H1e1a9, H4a1e, J2a2d1a and L3b1a12) whose coalescence dates correlate with the estimated time for the colonization of the islands (1st millennia CE). Additionally, we observe an asymmetrical distribution of mtDNA haplogroups in the ancient population, with certain haplogroups appearing more frequently in the islands closer to the continent. This reinforces results based on modern mtDNA and Y-chromosome data, and archaeological evidence suggesting the existence of two distinct migrations. Comparisons between insular populations show that some populations had high genetic diversity, while others were probably affected by genetic drift and/or bottlenecks. In spite of observing interinsular differences in the survival of indigenous lineages, modern populations, with the sole exception of La Gomera, are homogenous across the islands, supporting the theory of extensive human mobility after the European conquest.

genetics↗