Canopy laser scanning to study the complex architecture of large old trees Barbara D'hont1 , Professor Kim Calders1 , Professor Alexandre Antonelli6 , Dr. Thomas Berg7 , Dr. Karun Dayal1 , Dr. Leonard Hambrecht5 , Dr. Maurice Leponce2,3, Prof. Arko Lucieer5 , Olivier Pascal4 , Professor Pasi Raumonen8, Professor Hans Verbeeck1 1Q-ForestLab, Department of Environment, Ghent University, Ghent, Belgium, 2Royal Belgian Institute of Natural Sciences, Brussels, Belgium, 3Université Libre de Bruxelles, Brussels, Belgium, 4Fonds de Dotation Biotope Pour La Nature, France, 5School of Geography, Planning, and Spatial Sciences, University of Tasmania, , Australia, 6Royal Botanic Gardens, Kew, Richmond, Surrey, United Kingdom, 7ARAÇÁ Project, Nova Friburgo, Rio de Janeiro, Brazil, 8Faculty of Information Technology and Communication Sciences, Tampere University, Tampere, Finland Large trees are keystone structures providing multiple ecosystem functions in forests all around the world: they disproportionately contribute to forest biomass and biodiversity. Large trees can have an extremely complex structure, housing many epiphytes on their stem and branches. High point-density 3D point clouds, in which leaves and epiphytes in the tree can be distinguished, are useful to make the link between the distribution of organisms on the tree, the tree architecture and its microclimate. In addition, a comprehensive branching model can improve above ground biomass (AGB) estimates. Highly detailed, complete point clouds of large trees are, however, exceptionally difficult to derive. With terrestrial laser scanning, the state-of-the-art method to capture 3D tree structure, the plant material blocks the view of (or, occludes) the top part of the dense crown. Drone or airborne laser scanning data on the other hand, lacks detail in the subcanopy. Combining these two methods minimises occlusion; however, increased distance from the tree to the scanner still leads to a relatively low resolution of the canopy point clouds. To improve the level of precision of the tree point clouds, we introduce a new concept, called canopy laser scanning (CLS). With CLS, a laser scanner is operated statically inside the tree canopy, reducing the distance between the area of interest and the instrument. We lifted a high-end laser scanner (RIEGL vz-400(i)) inside the canopy of six large emergent trees. Four of these trees are located in different types of tropical rainforests in Colombia, Brazil and Peru. They are part of biodiversity programs in which organisms and their spatial distributions are studied (Life On Trees, Araçá). The two other trees are famous giants located in the wet temperate eucalypt forests of southern Tasmania. We will present the practical aspects of CLS, evaluate the extra value of using canopy scans, looking at occlusion and point cloud precision, estimate epiphyte cover and AGB. We demonstrate that canopy laser scanning opens up new opportunities in sciences in which multi-disciplinary teams perform in depth research on large individual trees.
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RBINS Staff Publications 2023
The extent and impact of Early Medieval population movements on the establishment of trade and cultural networks across the North Sea have been the subject of debate for centuries. Analyzing ancient genomes from the Flemish coast, we find two distinct ancestry groups merging in a Late Merovingian community: the major group with a dense network of distant relationships among individuals and genetic affinity to populations around the North Sea coast and the minor group representing likely continental Gaulish ancestry of unrelated individuals from various inland sources. We also find evidence of local continuity suggesting that similarly to Britain, the Early Medieval population movements had a long-term impact and were integral to the formation of the Flemish population. The Merovingian period (5th to 8th cc AD) was a time of demographic, socioeconomic, cultural, and political realignment in Western Europe. Here, we report the whole-genome shotgun sequence data of 30 human skeletal remains from a coastal Late Merovingian site of Koksijde (675 to 750 AD), alongside 18 remains from two Early to Late Medieval sites in present-day Flanders, Belgium. We find two distinct ancestries, one shared with Early Medieval England and the Netherlands, while the other, minor component, reflecting likely continental Gaulish ancestry. Kinship analyses identified no large pedigrees characteristic to elite burials revealing instead a high modularity of distant relationships among individuals of the main ancestry group. In contrast, individuals with >90% Gaulish ancestry had no kinship links among sampled individuals. Evidence for population structure and major differences in the extent of Gaulish ancestry in the main group, including in a mother?daughter pair, suggests ongoing admixture in the community at the time of their burial. The isotopic and genetic evidence combined supports a model by which the burials, representing an established coastal nonelite community, had incorporated migrants from inland populations. The main group of burials at Koksijde shows an abundance of >5 cM long shared allelic intervals with the High Medieval site nearby, implying long-term continuity and suggesting that similarly to Britain, the Early Medieval ancestry shifts left a significant and long-lasting impact on the genetic makeup of the Flemish population. We find substantial allele frequency differences between the two ancestry groups in pigmentation and diet-associated variants, including those linked with lactase persistence, likely reflecting ancestry change rather than local adaptation.
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RBINS Staff Publications 2024
The aim of this study is to investigate isotopic variability in archaeological (n=85) and modern (n=29) freshwater fish specimens from Switzerland. Here, carbon (δ13C) and nitrogen (δ15N) stable isotope ratio analysiswas performed on bone collagen samples of pike (Esox lucius), perch (Perca fluviatilis), barbel (Barbus barbus), roach (Rutilus rutilus) and carp (Cyprinus carpio) fromeleven archaeological (11th to 18/19th centuries CE) andmodern sites. The archaeological vs. modern fish data revealed significant isotopic differences for pike, perch and barbel (δ13Cp≤ 0.03; δ15Np≤ 0.008), and provides possible evidence for a temporal change in Swiss aquatic ecosystems from Medieval to modern times. In comparison to archaeological fish (δ13C mean ± SD; −23.3 ± 1.6‰; δ15N mean ± SD; 8.3 ± 1.8‰), the modern fish samples show decreased δ13C and increased δ15N values (δ13C mean± SD; −27.4 ± 2.3‰; δ15N mean± SD; 12.5± 4.1‰) that can be associated with anthropogenic effects: fossil fuel combustion, deforestation and organic waste in the form of sewage and fertilizers. The isotopic signatures of archaeological fish remains indicate a local fishery practice, but also the exploitation of distant fishing grounds and freshwater fish transportation. Furthermore, a diachronic isotopic trend is observed in young perch from sites in Basel, dating between the 12th and 15/16th centuries CE, and the isotopic data from the Rhine freshwater fish (18/19th century CE) suggests that a significant shift in the river's trophic state was possibly caused by organic pollution fromurban and industrial wastewater. This retrospective research illustrates possible natural processes and human activitieswhich can cause differences in fish stable isotope data and highlights the ability to elucidate changes in past bodies of water. Furthermore, this study provides an interpretative framework for additional palaeoenvironmental studies and modern restoration projects focused on freshwater ecosystems.
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RBINS Staff Publications 2016
Carbon and nitrogen stable isotope ratios were measured in 157 fish bone collagen samples from 15 different archaeological sites in Belgium which ranged in ages from the 3rd to the 18th c. AD. Due to diagenetic contamination of the burial environment, only 63 specimens produced results with suitable C:N ratios (2.9-3.6). The selected bones encompass a wide spectrum of freshwater, brackish, and marine taxa (N = 18), and this is reflected in the d13C results (-28.2‰ to -12.9‰). The freshwater fish have d13C values that range from -28.2‰ to -20.2‰, while the marine fish cluster between -15.4‰ to -13.0‰. Eel, a catadromous species (mostly living in freshwater but migrating into the sea to spawn), plots between -24.1‰ to -17.7‰, and the anadromous fish (living in marine environments but migrating into freshwater to spawn) show a mix of freshwater and marine isotopic signatures. The d15N results also have a large range (7.2‰ to 16.7‰) indicating that these fish were feeding at many different trophic levels in these diverse aquatic environments. The aim of this research is the isotopic characterization of archaeological fish species (ecology, trophic level, migration patterns) and to determine intra-species variation within and between fish populations differing in time and location. Due to the previous lack of archaeological fish isotope data from Northern Europe and Belgium in particular, these results serve as an important ecological backdrop for the future isotopic reconstruction of the diet of human populations dating from the historical period (1st and 2nd millennium AD), where there is zooarchaeological and historical evidence for an increased consumption of marine fish.
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