Reappearance of old growth elements in lowland woodlands in northern Belgium : do the associated species follow?

The forest cover of the western European lowland plain has been very low for centuries. Remaining forests were intensively managed, and old-growth elements like veteran trees and coarse woody debris became virtually absent. Only over the last decades have these old-growth elements progressively redeveloped in parks, lanes and forests, and have now reached their highest level over the last 500-1000 years. Biodiversity associated with these old-growth elements makes up an important part of overall forest biodiversity. The ability of species to recolonise the newly available habitat is strongly determined by limitations in their dispersal and establishment. We analyse the current status and development of old-growth elements in Flanders (northern Belgium) and the process of recolonisation by means of specific cases, focussing on saproxylic fungi and saproxylic beetles. Our results show that 'hotspots' of secondary old growth, even isolated small patches, may have more potential for specialised biodiversity than expected, and may provide important new strongholds for recovery and recolonisation of an important share of old-growth related species

Tree species mapping by combining hyperspectral with LiDAR data

This study deals with data fusion of hyperspectral and LiDAR sensors for forest applications. In particular, the added value of different data sources on tree species mapping has been analyzed. A total of seven species have been mapped for a forested area in Belgium: Beech, Ash, Larch, Poplar, Copper beech, Chestnut and Oak. Hyperspectral data is obtained from the APEX sensor in 286 spectral bands. LiDAR data has been acquired with a TopoSys sensor Harrier 56 at full waveform. Confirming previous research [1], it has been found that airborne LiDAR data, when combined with hyperspectral data, can improve classification results. The novelty of this study is in the quantification of the contribution of the individual data sources and their derived parameters. LiDAR information was combined with the hyperspectral image in a data fusion approach. Different data fusion techniques were tested, including feature and decision fusion. Decision fucsion produced optimal results, reaching an overall accuracy of 96% (Kappa [3] of 0:95)

Effect of hyperspectral image denoising with PCA and total variation on tree species mapping using Apex Data

In this paper, the impact of image denoising on feature selection and tree species mapping accuracy is assessed. We apply a novel algorithm for hyperspectral (HS) image denoising using principal component analysis (PCA) and total variation (TV). The method is embedded in an object‐based classification framework and tested for complex forests with closed canopies and scarce reference data. Results show that, under the given conditions, HS image denoising is beneficial yielding stable mapping results with acceptable accuracy levels. Denoising also affected feature selection processing time with a time gain of 41.6%

Reconstructing the history of the silva carbonaria, an enigmatic charcoal-burners-forest in Central Belgium

The Sonian forest, situated south of Brussels, is one of the last remnants of a vast forest that is believed to have covered the larger part of central Belgium up to at least the end of the Early Medieval period and which is mentioned as the silva carbonaria (Latin for ‘charcoal burners forest’) in several historical texts. The strict reserves within the forest, together with several other European old growth beech forests, were listed as a UNESCO world heritage site since 2017. Extensive archives allow us to reconstruct its history over the last 500 years, yet, little is known however on the extent, composition and exploitation of this forest before that time.. We now present the preliminary results of an interdisciplinary study of archaeological remains of charcoal and metal production sites from this forest, which provide a lot of new information on its history and evolution. This study includes the detection of charcoal and metal production sites using LIDAR and geophysical methods, radiocarbon and OSL-dating of different types of features from these sites and anthracological analysis. In addition, the results also provide new information on the role of beech in the natural forest vegetation in the lowlands of NW-Europe

Heading for a fall: The fate of old wind-thrown beech trees (Fagus sylvatica) is detectable in their growth pattern.

peer reviewedCommon beech (Fagus sylvatica) is one of the most important deciduous tree species in European forests. However, climate-change-induced drought may threaten its dominant position. The Sonian Forest close to Brussels (Belgium) is home to some of the largest beech trees in the world. This UNESCO world heritage site is famous for its high density of very large beech trees as a result of its climatic suitability, fertile soil conditions, and past management. Here we utilized tree-ring data from increment cores to investigate the growth of these old and monumental beech trees, evaluating their growth trends, response to past climate, and the effect of mast years on 39 living and 16 recently wind-thrown trees. Our analysis reveals that the sampled trees were generally sensitive to spring and summer droughts but recovered quickly after such an extreme climatic event. The growth trend of living trees has remained high and only shows a slight, statistically insignificant, decline over the past 50 years. Although the overall growth rate remains strong (BAI 50 cm2/year), the past five decades have shown strong inter-annual growth variations due to frequent and more intense droughts combined with an increased frequency of mast years. We also found notable differences in growth patterns between the living trees and those that had recently been wind-thrown. While there were no significant differences between living and wind-thrown trees in response to droughts, heatwaves, or mast years when examining year-to-year growth changes, the wind-thrown trees did exhibit considerably lower overall growth rates and a significant downward trend in growth (BAI -0.57 cm2/year). This difference in growth trends has been apparent since at least the 1980s. Overall, the findings of this study can provide valuable insights for understanding the long-term dynamics of lowland beech forests and their responses to climate change

M & L Jaargang 29/6

Mimi Debruyn De wondere wereld van een 18de-eeuws receptenboek voor Kunst-Schilders, Vernissers, Vergulders en Marmelaers. [The wondrous world of an 18th century book of recipes for painters, varnishers, gilders and marblers.]In 1777 publiceerden de gebroeders Gimblet in Gent een receptenboek voor de kunst- en decoratieschilders van hun tijd. Dit encyclopedisch kookboek viel onder de aandacht van Mimi Debruyn, die er enthousiast in grasduinde op zoek naar wetenswaardigheden over de materialen en technieken van de toenmalige exterieurafwerking en binneninrichting.Ilse Boeren, Kris Vandekerkhove, Sara Adriaenssens, Dries Tys, Koen Deforce, Kristof Haneca en Jan Bastiaens - Relicten van houtskoolmeilers in het Zoerselbos. [Remnants of charcoal kilns in the old woodland Zoerselbos.]Thans één van de meest waardevolle bosgebieden in Vlaanderen was het Zoerselbos, tot het begin van de 19de eeuw, het tafereel van een belangrijke economische activiteit: de productie van houtskool. De overblijfselen hiervan recent en bij toeval ontdekt zijn slechts voor een geoefend oog zichtbaar en in Vlaanderen nauwelijks gekend. In opdracht van het agentschap Ruimte en Erfgoed trok een team van wetenschappers op verder onderzoek uit en werden de meilers in het Zoerselbos geïnventariseerd, onderzocht en geëvalueerd met het oog op hun behoud voor de toekomst.Guido Cuyt Archeologisch onderzoek door vrijwilligers in Vlaanderen. [Archaeological research by voluntary workers in Flanders.]De directeur van de Nationale Dienst voor Opgravingen wist het 30 jaar geleden al: Er zijn maar twee soorten archeologen, namelijk goeie en slechte. En beide soorten vind je zowel bij de beroeps- als bij de amateurarcheologen. De amateurarcheoloog, vroeger verguisd en later geherwaardeerd, dreigt de dag van vandaag opnieuw verdrongen te worden. Is er nog een toekomst? Guido Cuyt - zelf een gepassioneerd amateurarcheoloog - schetst de evolutie van de amateurarcheologie in Vlaanderen en pleit meteen ook voor bezinning en herprofilering.Lieve Viaene-Awouters Heraldiek in Vlaanderen. Dertig jaar Vlaamse Heraldische Raad. [Heraldry in Flanders. Thirty years of Flemisch Heraldic Council.]Wapenborden en heraldische voorstellingen zijn sinds de vroege middeleeuwen in Vlaanderen van grote historische betekenis. Al 30 jaar waakt een raad van deskundigen over het historisch en heraldisch verantwoord toekennen van nieuwe wapens en over hun uniform gebruik. De raad formuleert tevens adviezen ten behoeve van de bevoegde minister en probeert een antwoord te bieden op de wildgroei aan logos die hand over hand toeneemt. Een overzicht van drie decennia Vlaamse Heraldische Raad door Lieve Viaene-Awouters.Summar