Clusters of Quercus robur and Q. petraea at the Veluwe (the Netherlands)

In this report three main questions were studied: (1) are oak clusters genetically identical, (2) can leaf morphology be used to identify clonal structures of oak and (3) what is the origin of oak clusters. The study sites were situated in a drift sand area (Maanschoten) as well as in an area with pre-glacial material (Wilde Kamp)

Bosjes van Poot : onderzoek eikenclusters en effecten van honden

De Bosjes van Poot is een duingebied in de gemeente Den Haag, dat samen met het Westduinpark in 1990 door het Rijk is aangewezen als “Natuurmonument Westduinpark”. Daarmee werden deze gebieden onder de werking van de Natuurbeschermingswet gebracht. In het gebied bevinden zich een groot aantal eikenclusters. Dit rapport doet verslag van een onderzoek naar de genetische oorsprong, de ouderdom, de ontstaanswijze en de waardestelling van deze eikenclusters. Daarnaast is onderzoek verricht naar de mogelijke effecten van honden op de groei en vitaliteit van de eikenclusters en wordt een beheeradvies gegeve

Eikenclusters op de Veluwe

Op de Veluwe worden op verschillende plekken groepen eiken aangetroffen. Mogelijk behoren ze tot oorspronkelijk inheems materiaal, en zijn ze ontstaan uit hakhout. In dat geval is sprake van een cultureel erfgoed. In opdracht van Gelders Landschap worden momenteel eikenclusters onderzocht op hun ontstaansgeschiedenis

Groei en productie van zwarte els in Nederland

In the Netherlands growth and yield research on black alder was done on a limited scale from 1965 to 1990. This regards two studies by the Dorschkamp/IBN research institute; together with the permanent sample plots from the timber prognosis system HOSP, this comprises a dataset of 14 plots with 59 recordings. In addition, the information from 518 stands of the Fourth National Forest Inventory was used. For the development of top height htop with age t Jansen’s et al. polymorphic model with site index h50 and four additional parameters fitted best. The diameter at a height of 7 m (d7) was estimated from data of the Fourth National Forest Inven-tory. The diameter development up to stand height of 7 m was described with a model of Jansen et al., a power function in htop and the estimated value for d7. From a stand height of 7 m upwards, the basal area increment (iG) was also described by Jansen’s et al. model based on a power function with t, year of recording (yor), and the stand density of Hart (S %). For S% > 15.7 the basal area increment decreases non-linear with increasing S %. The model contains a correction factor for yor, although this was not significant, as the year of recording (yor), turned out to be not significant. The effect of thinning on the diameter after thinning was modelled with the La Bastide-Faber model. The models were used to construct a yield table with five site classes and one thinning intensity

Opbrengsttabellen Nederland 2018

In deze bundel zijn opbrengsttabellen van 15 boomsoorten opgenomen. In vergelijking met de tot nu toe geldende opbrengsttabellen uit 1996, bevat deze bundel meer soorten, meer dunningregimes, en zijn alle tabellen gebaseerd op Nederlandse meetgegevens. Voor 10 soorten zijn tabellen met zowel een matige als sterke dunning opgenomen. Voor de Japanse Lariks zijn twee regionale tabellen opgenomen. De populier heeft in deze bundel een tabel voor bomen in lijnbeplanting, naast de tabellen voor bos met diverse plantverbanden. Per soort is het rapport van de onderliggende studie weergegeven. Al deze studies volgden in grote lijnen de studie Groei en productie van douglas in Nederland. Becking's dunningproeven ontsloten. In vergelijking met de studies uit 1996, blijkt enerzijds de hoogtegroei per boniteit te verschillen (slechte boniteiten starten lager dan goede boniteiten, maar halen de groei later deels in). Anderzijds blijk de range tussen de beste en slechtste boniteit vaak ruimer dan in de eerdere studies

Quantifying in situ phenotypic variability in the hydraulic properties of four tree species across their distribution range in Europe

Many studies have reported that hydraulic properties vary considerably between tree species, but little is known about their intraspecific variation and, therefore, their capacity to adapt to a warmer and drier climate. Here, we quantify phenotypic divergence and clinal variation for embolism resistance, hydraulic conductivity and branch growth, in four tree species, two angiosperms (Betula pendula, Populus tremula) and two conifers (Picea abies, Pinus sylvestris), across their latitudinal distribution in Europe. Growth and hydraulic efficiency varied widely within species and between populations. The variability of embolism resistance was in general weaker than that of growth and hydraulic efficiency, and very low for all species but Populus tremula. In addition, no and weak support for a safety vs. efficiency trade-off was observed for the angiosperm and conifer species, respectively. The limited variability of embolism resistance observed here for all species except Populus tremula, suggests that forest populations will unlikely be able to adapt hydraulically to drier conditions through the evolution of embolism resistance.Peer reviewe

Bossen in de berm: geschikt als biomassa en bouwmateriaal?

Met de aanplant van bossen langs snelwegen en tankstations wil Rijkswaterstaat bijdragen aan de klimaatdoelen. Een deel van het hout kan worden gebruikt voor het opwekken van groene stroom. In een pilot onderzoekt Wageningen University & Research (WUR) hoe dat het beste kan worden aangepakt

Markers inside wood : tree rings as archives of insect outbreaks, drift-sand dynamics, and spring flooding

MARKERS INSIDE WOOD – TREE RINGS AS ARCHIVES OF INSECT OUTBREAKS, DRIFT-SAND DYNAMICS AND SPRING FLOODING Trees are long-living organisms that record ecologically relevant information in their xylem that can be accessed by dendrochronology, the study of tree rings. Specific environmental events like frost, fire, floods, burial or wounding may drastically alter the anatomy of tree rings and consequently may leave markers inside trees. These wood-anatomical markers have shown a high potential for studying past environmental events with an annual or even intra-annual temporal resolution. In this thesis, the temporal resolution of wood-anatomical markers was studied to date wounds made by invasive Anoplophora beetles. In addition, the accuracy of dating drift-sand dynamics and spring flooding events was studied using wood-anatomical changes, which were expected to occur after drastic changes in the stem and root environment. It was hypothesised that all these wood-anatomical markers can be used with an intra-annual resolution. Field studies in combination with experiments were used to study tree growth and the formation of wood-anatomical markers in Japanese maple (Acer palmatum Thunb.) and pedunculate oak (Quercus robur L.). It was shown that wounds in Japanese maple can be assigned to three different phases related to tree-ring development: (1) wounds that originated during dormancy are located at the tree-ring boundary; (2) wounds that originated during the growing season are located within the tree ring. If wound-xylem formation was observed locally around the wound (3), it could either imply that the wound originated at the very end of the growing season or just before the onset of radial growth or during dormancy when temperature was high. Dating wounds caused by the formation of exit holes has proved to be very significant in fighting invasive insect outbreaks. By pinpointing the exact year and season when Anoplophora beetles emerged, it can be substantiated whether exit holes in imported trees were formed at the location of import. This knowledge can subsequently be used to draw up customised eradication measures and allocate proper surveillance plans and population dynamics can be reconstructed. Living trees in drift-sand areas may contain burial or exposure signals even if the sand under which they were buried has long since disappeared. Anatomical changes in pedunculate oak trees due to burial are not a result of physical changes in the stem environment that directly affect the cambium. Instead they are most likely the result of adventitious root formation that transforms lower parts of the stem into root, and concomitantly induces a change from stem to root anatomy. As the formation of a wood-anatomical marker caused by burial can be delayed by many years or might be entirely absent, depending on the formation of adventitious root formation, its presence only allows for an estimate on minimum burial age. Flood rings containing anomalously small earlywood vessels in pedunculate oak are formed in response to spring flooding within a narrow time window related to cambial phenology. They can be induced if a flooding event has occurred for at least two weeks during spring. The extreme reduction in vessel size is a consequence of a delay in vessel formation due to anoxic conditions related to flooding. Flood rings however, provide only limited information on the duration of flooding, as the flooding may have lasted for months (during winter) before it is recorded. It is concluded that the origin of wood-anatomical markers largely determines the temporal resolution. Markers induced by wounding or flooding show a high intra-annual temporal resolution and immediate effect on tree functioning, whereas burial might not be recorded three years after the triggering events. The different wood-anatomical markers addressed in this thesis illustrate the relevance of studying the mechanism behind the formation of markers for correct interpretation of the specific triggering factor as well as their temporal resolution. Only with this knowledge it becomes possible to reliably use wood-anatomical markers as archives to understand and reconstruct dynamics in geomorphic, entomologic, pathogenic or climatic factors.</p