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In dit artikel berichten we over twee verschillende experimenten: een strooiseltransplantatie-experiment op de Johannahoeve (Arnhem) met data over diverse groepen bodemorganismen waaronder aaltjes, en een verteringsexperiment op Nieuw Dennenlust (Beekbergen) met een uitgebreide analyse van voedselgildes (soorten met een overeenkomstig dieet, bijvoorbeeld planteneters, schimmelzuigers, et cetera) van bodemmicroarthropoden.

Is de veerkracht van onze bomen en bossen toereikend om hetere endrogere periodes en aanhoudende bodemverzuring in de toekomst teoverleven? Welke bosbeheermaatregelen zijn mogelijk en nodig om deverschillende bosfuncties te behouden? Om deze vragen te beantwoordenen de gevolgen van klimaatverandering en bodemverzuring in kaart tebrengen zijn wij – een consortium van wetenschappers en bosgebruikers –een bosexperiment gestart. Het doel is om de reacties van bomen, bodemsen uiteindelijke hele bossen op verschillende beheeringrepen te begrijpenin relatie tot veranderingen in bodem en klimaat. Dit artikel geeft eenintroductie van het experiment.

Bodemverzuring heeft in Nederland en Vlaanderen geleid tot minder vitale boomgroei. Het planten van bomen met rijkstrooisel blijkt een veelbelovende strategie te zijn om de bodemkwaliteit in bossen met arme, zure bodems te verbeteren. In het kader van het project Correlatief onderzoek Rijkstrooiselsoorten in Natuurgericht Bosbeheer onderzochten we het effect van de aanwezigheid vanAmerikaanse vogelkers op de diktegroei van zomereik

Introduction & Aims: Small studies have found that black patients with autoimmune hepatitis (AIH) present with more aggressive disease. We aimed to characterize the presentation and outcome in black and white patients with AIH. Methods: We performed a retrospective study, collecting information from databases of patients with AIH attending the Institute of Liver studies at King's College Hospital, London (1971–October 2015, the Royal Free Hospital, London (1982 through December 2016) and the multicenter Dutch Autoimmune Hepatitis Study Group cohort (2006–August 2016). We identified 88 black patients with AIH and we compared their clinical characteristics and outcomes to 897 white patients with AIH. Results: Black patients presented at a younger age (median 38 years vs 45 years) (P =.007), had higher IgG levels (mean 31.0 mg/dL vs 27.5 mg/dL) (P =.04), but there were no significant differences between groups in auto-antibody profiles, International AIH Group scores, or sex distribution of disease. A higher proportion of black patients had systemic lupus erythematosus (10%) than white patients (2%) (P ≤.001). There was no significant difference in proportions of patients with a response to standard therapy (86% for black patients vs 91% for white patients; P =.20) or in rate of relapse (57% vs 50%; P =.3). Despite this, black patients had an increased risk of liver transplantation and liver-related death (hazard ratio 2.4, 95% confidence interval, 1.4–4.0; P <.001). Overall mortality was similar between the two groups. Conclusion: In a comparison of black and white patients with AIH in Europe, we found that black patients present at a younger age, have higher levels of IgG levels, and a greater proportion have SLE. We also found black patients to have a greater risk of liver transplantation and liver-related mortality, indicating more aggressive disease.

Mixed-species forests have become widely studied in the recent years because of their potential to mitigate risks associated with climate change. However, their growth dynamics are often difficult to predict because species interactions vary with climatic and edaphic conditions, stand structure and forest management. We examined species interactions in mixtures of Scots pine (Pinus sylvestris) and pedunculate oak (Quercus robur) under climate change and for varying soil conditions in the Netherlands, over a period of 30 years. We parameterized, calibrated and validated the 3-PGmix model for mixing effects in Scots pine and oak mixtures and analysed these effects under climate change. 3-PGmix performed well for the variety of forest stands examined throughout the Netherlands. Furthermore, it was also able to reproduce mixing effects for each species in mixtures compared to monocultures for the growing conditions examined. Simulated climate change resulted in lower productivity of oak and higher productivity of Scots pine, compared to the current climate. This was observed for both monospecific stands and mixtures. The mixture of Scots pine and oak showed clear but limited overyielding (mixture yield greater than the mean of the monocultures), which was mainly attributed to oak. This was maintained under the most extreme climate scenario for 2050, implying that for oak, increased growth due to mixing with Scots pine was larger than the reduction in productivity under the future climate. On resource-limited soils, Scots pine competitiveness was increased, and this was maintained under a warmer and drier climate. Our results suggest that projected changes in climate will influence species interactions and result in increased Scots pine productivity, notably on poor sandy soils, which are typical of the Netherlands.

ForestGEO is a network of scientists and long-term forest dynamics plots (FDPs) spanning the Earth's major forest types. ForestGEO's mission is to advance understanding of the diversity and dynamics of forests and to strengthen global capacity for forest science research. ForestGEO is unique among forest plot networks in its large-scale plot dimensions, censusing of all stems ≥1 cm in diameter, inclusion of tropical, temperate and boreal forests, and investigation of additional biotic (e.g., arthropods) and abiotic (e.g., soils) drivers, which together provide a holistic view of forest functioning. The 71 FDPs in 27 countries include approximately 7.33 million living trees and about 12,000 species, representing 20% of the world's known tree diversity. With >1300 published papers, ForestGEO researchers have made significant contributions in two fundamental areas: species coexistence and diversity, and ecosystem functioning. Specifically, defining the major biotic and abiotic controls on the distribution and coexistence of species and functional types and on variation in species' demography has led to improved understanding of how the multiple dimensions of forest diversity are structured across space and time and how this diversity relates to the processes controlling the role of forests in the Earth system. Nevertheless, knowledge gaps remain that impede our ability to predict how forest diversity and function will respond to climate change and other stressors. Meeting these global research challenges requires major advances in standardizing taxonomy of tropical species, resolving the main drivers of forest dynamics, and integrating plot-based ground and remote sensing observations to scale up estimates of forest diversity and function, coupled with improved predictive models. However, they cannot be met without greater financial commitment to sustain the long-term research of ForestGEO and other forest plot networks, greatly expanded scientific capa

Earth’s surface is changing rapidly due to anthropogenic disturbance and thus threatening the conservation of entire biomes: from deserts to tropical rainforests and from oceans to mountains. Within this spectrum, forests are one of the biomes which has suffered the most due to the exploitation of natural resources and the expansion of the urban environment into natural landscapes. Specially the case of temperate forests which offer favourable conditions for a variety of economic activities, such as: food and timber production but as well for a blooming human life. The high concentration of humans in temperate forests has led to high indices of land conversion and fragmentation, threatening the conservation of the unique biodiversity harboured in these forests. For example, the loss of apex predators has led to the overabundance of wild ungulates in most of the temperate forests, increasing the top-down control that these animals have over vegetation. The top-down control of wild ungulates can influence several forest attributes such as forest diversity, structure and functioning. However, these effects are highly dependent on ungulate density, successional forest stage and the ungulate assemblage composition. Yet, there is a limited amount of field and experimental studies that elaborate on these important factors, mainly because there is a lack of long-term exclosures and a lack of studies that have evaluated the effect of a complete ungulate density gradient on forests in the same region. This thesis aims to evaluate the effects of wild ungulates on temperate forests at different scales. That is, how do wild ungulates affect forests at different 1) spatial scales (from areas with low to areas with high ungulate abundance)?, 2) temporal scales (from short-term to long-term effects)?, and 3) hierarchical scales (from trophic levels of primary producers to detritivores)? To tackle these questions, robust methods were designed in this thesis, such as a chronosequence

Trees are affected by a set of spatially and/or temporarily varying biotic and abiotic factors. The effect of these factors is reflected in the width and structure of tree rings, which are widely used to study species ecology and their responses to climate. Moreover, tree-ring width time series are also used for dating and identification of the geographical origin of archaeological or historical timber – dendroprovenancing. The latter is usually done by statistical matching of tree-ring width sequence of a given timber to a network of regional and local chronologies from the same species or genera. However, despite multiple successful applications, this method also has clear pitfalls, such as lack of long reference tree-ring width chronologies from areas with intensive logging history; or possible strong teleconnections between reference chronologies over large distances leading to coarse-scale results. Therefore, to overcome these limitations and to improve dendroprovenancing results, other wood-anatomical features or chemical characteristics have to be used. The potential of additional variables retrieved from the wood has been recently tested and showed promising results for timber tracking, e.g. its chemical composition or DNA. However, until now time series of xylem-anatomical features have been largely ignored in timber-provenancing studies. This is most likely due to the time-consuming and labour-intensive data acquisition and challenging preparation of archaeological timber for precise wood-anatomical measurements. But with recent improvements in wood- preparation techniques and image-analysis software, it became possible to acquire a sufficient amount of data derived from various xylem-anatomical features in an efficient way. This thesis aims to evaluate the value of xylem-anatomical features as well as of archaeological DNA (aDNA) in addition to TRW for timber-provenancing studies. In the context of the ForSEAdiscovery project, the potential of vessel size

Ungulates in temperate regions are increasing in range and abundance, leading to concerns that browsing and trampling reach levels that hamper tree recruitment and forest regeneration. However, studies that actually quantify the long-term effects of ungulates on forest succession are scarce. Here, we use a chronosequence of ungulate exclosures (fenced) and control (unfenced) plots to assess the long-term effects of ungulates on forest structure, diversity and litter depth in forests on poor sandy soils at the Veluwe, the Netherlands, which have moderate ungulate densities ( = 13.6 ungulates km−2). We surveyed the vegetation in 27 paired fenced and unfenced plots that ranged from 1 to 33 years old, and measured seven variables to characterize forest structure (stem density, canopy cover and understory vegetation cover), composition (Shannon diversity, species richness and conifer proportion) and leaf litter depth. We found on average that fencing compared to unfencing reduced understory vegetation cover (fenced = 64.3 ± 20.2%, unfenced = 80.3 ± 19.4%), increased canopy cover (fenced = 47.4 ± 30.1%, unfenced = 29.3 ± 21.1%), tree species richness (fenced = 4.5 ± 1.3 spp., unfenced = 2.7 ± 1.2 spp.), tree Shannon diversity (fenced = 1.1 ± 0.3 index, unfenced = 0.7 ± 0.3 index) and litter layer depth (fenced = 4.4 ± 1.4 cm, unfenced = 2.4 ± 1.1 cm). While fenced plots developed woody vegetation with palatable broadleaved species such as Betula pendula, Betula pubescens, Prunus serotina, and Quercus robur, unfenced plots were not associated with any particular tree species. Our results show that current ungulate densities in this system have pronounced long-term effects on forest structure, composition and litter depth, implying that ungulates can slow down natural succession of temperate forest, from light demanding to shade tolerant species, by keeping the system in an arrested state consisting of light demanding species.

Aim: Spatial variations of environmental conditions translate into biogeographic growth patterns of tree growth. This fact is used to identify the origin of timber by means of dendroprovenancing. Yet, dendroprovenancing attempts are based on ring-widths measurements, and neglect additional tree-ring parameters. To explore the effect of including additional variables in dendroprovenancing, we investigate whether and, if so, why the incorporation of wood-anatomical parameters can increase the precision of identifying the origin of oak wood. Since such features reflect environmental conditions of different periods – which vary between source regions – we hypothesize that their inclusion allows more precise dendroprovenancing. Location: Europe, Spain. Taxon: Quercus robur L., Quercus petraea (Matt.) Liebl., Quercus faginea Lam., Quercus pyrenaica Willd. Methods: We sampled four oak species resembling a longitudinal and an elevational/continental gradients. We measured multiple tree-ring variables to (1) extract meaningful variables, (2) represent statistical relations among variables, (3) analyse regional-specific growth patterns in individual time series and (4) determine underlying climate-growth relationships. Leave-one-out analyses were used to test whether a combination of selected variables allows dendroprovenancing of a randomly selected tree within the area. Results: A combination of latewood width and earlywood vessels size can be used to pin-point the origin of oak wood with higher precision than latewood width only. Variation in latewood widths appointed the wood to areas across the longitudinal gradient, whereas variation in vessels assigned wood to locations along a latitudinal/topographic gradient. The climatic factors behind these gradients are respectively an East-West gradient in June-July temperature, and a North-South gradient in winter/ spring temperatures. The leave-one-out analyses supported the robustness of the results. Main conclusions: Integrat

When tree‐species mixtures are more productive than monocultures, higher light absorption is often suggested as a cause. However, few studies have quantified this effect and even fewer have examined which light‐related interactions are most important, such as the effects of species interactions on tree allometric relationships and crown architecture, differences in vertical or horizontal canopy structure, phenology of deciduous species or the mixing effects on tree size and stand density. In this study, measurements of tree sizes and stand structures were combined with a detailed tree‐level light model (Maestra) to examine the contribution of each light‐related interaction on tree‐ and stand‐level light absorption at 21 sites, each of which contained a triplet of plots including a mixture and monocultures ofFagus sylvaticaandPinus sylvestris(63 plots). These sites were distributed across the current distribution of these species within Europe. Averaged across all sites, the light absorption of mixtures was 14% higher than the mean of the monocultures. At the whole community level, this positive effect of mixing on light absorption increased as canopy volume or site productivity increased, but was unrelated to climate. At the species population or individual tree levels, the mixing effect on light absorption resulted from light‐related interactions involving vertical canopy structure, stand density, the presence of a deciduous species (F. sylvatica), as well as the effects of mixing on tree size and allometric relationships between diameter and height, crown diameter and crown length. The mixing effects on light absorption were only correlated with the mixing effects on growth forP. sylvestris, suggesting that the mixing effects on this species were driven by the light‐related interactions, whereas mixing effects onF. sylvaticaor whole community growth were probably driven by non‐light‐related interactions. Synthesis. The overall positive effect of mixing on

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., Van 1965 tot 1990 is in Nederland op bescheiden schaal groei- en productieonderzoek bij de zwarte els uitgevoerd. Dat betreffen twee studies van de Dorschkamp/IBN. Samen met de perma-nente steekproeven uit de HOSP zijn 14 proefperken met 59 opnamen beschikbaar. Daarnaast waren er de gegevens van 518 opstanden uit de 4e Bosstatistiek. Voor de ontwikkeling van de opperhoogte htop met de leeftijd t werd het heteromorfe model van Jan-sen et al. gekozen, met asymptoot en 4 andere parameters. Als site index is voor de h50 gekozen. De diameter bij een hoogte van 7 m (d7) geschat met data uit de 4e Bosstatistiek, voor de groei tot d7 werd een powerfunctie in htop gebruikt. Met een powerfunctie werd de grondvlakbijgroei iG verklaard met leeftijd, t en standruimte index van Hart S %. Voor S % > 15.7 daalt de grondvlakbijgroei met een niet-lineaire functie in S %. Het effect van de dunning op de diameter na dunning is gemodelleerd met het La Bastide-Faber mo-del. Er is een opbrengsttabel gemaakt met een matige laagdunning en vijf boniteiten.

In the Netherlands growth and yield research on sycamore was done from 1976 to 2001. This includes studies by the Dorschkamp/IBN research institute and by Wageningen University. To-gether with the permanent sample plots from the timber prognosis system HOSP, this comprises a dataset of 32 plots with 113 recordings. For the development of top height htop with age t Cieszewski’s polymorphic model with site index h50 and three additional parameters fitted best.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 initial spacing (N0). From a stand height of 7 m upwards, the basal area in-crement (iG) was described by Jansen’s et al. model based on a power function with htop, t, year of re-cording (yor), and the stand density of Hart (S %). For S% > 16.3 the basal area increment decreases non-linearly with increasing %. 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., Van 1976 tot 2001 is in Nederland groei- en productieonderzoek bij de gewone esdoorn uitgevoerd. Dat betreft studies van de Dorschkamp/IBN en van Wageningen Universiteit. Samen met de permanente steekproeven uit de HOSP zijn 32 proefperken met 113 opnamen beschikbaar.Voor de ontwikkeling van de opperhoogte htop met de leeftijd t werd het heteromorfe model van Cieszewski gekozen, met asymptoot en 3 andere parameters. Als site index is voor de h50 gekozen. De diameter bij een hoogte van 7 m (d7) werd het best verklaard met een model van Jansen et al. een functie in htop en het beginstamtal (N0), voor de groei tot d7 werd een powerfunctie gebruikt.Met een model van Jansen et al. werd de grondvlakbijgroei iG verklaard, een powerfunctie met htop, t, standruimte index van Hart (S %). Voor S % > 16.3 daalt de grondvlakbijgroei met een niet-lineaire functie in S %. Het model bevat ook de factor opnamejaar (yor) deze was niet significant. Het effect van de dunning op de diameter na dunning is gemodelleerd met het La Bastide-Faber model.Er is een opbrengsttabel gemaakt met een sterke laagdunning en vijf boniteiten.

In the Netherlands growth and yield research on common beech was done from 1960 to 1992 at very small scale. This includes studies by Becking and by the Dorschkamp/IBN research insti-tute. Together with the permanent sample plots from the timber prognosis system HOSP, all this comprises a dataset of 47 plots with 169 recordings. For the development of top height (htop) with age (t) Cieszewski’s model with site index h70 and three additional parameters fitted best. The diame-ter development up to stand height of 7 m was described with the model by Jansen et al. based on htop and initial density (N0). From a stand height of 7 m and up, the basal area increment (iG) was also described by a model from Jansen et al., based on a power function with htop, t, year of recording (yor), and the stand density of Hart (S %). For S % > 17.6 the basal area increment drops strongly with increasing S %. The model contains a correction factor for yor, which unfortunately could not be esti-mated from the plot data. The effect of thinning on the diameter after thinning was modelled with a modified La Bastide-Faber model. With all models together, a stand projection model was con-structed, which describes the measured stand development moderately well. The model was used to construct yield tables for with five site classes and six thinning intensities, Van 1960 tot 1992 is in Nederland op zeer bescheiden schaal groei- en productieonderzoek bij de beuk uitgevoerd. Dat betreft de studies van Becking en de Dorschkamp/IBN. Samen met de permanente steekproeven uit de HOSP zijn 47 proefperken met 169 opnamen beschikbaar.Voor de ontwikkeling van de opperhoogte (htop) met de leeftijd (t) werd het heteromorfe model van Cieszewski gekozen, met asymptoot en 3 andere parameters. Als site index is voor de h70 gekozen. De diameterontwikkeling tot een opstandhoogte van 7 m werd verklaard met het model van Jansen et al. met de variabelen htop en het beginstamtal (N0). Vanaf een opstandhoogte van 7 m werd de grondvlakbijgroei (iG) verklaard met een ander model van Jansen et al. een powerfunctie met htop, t, jaar van opnamen (yor) en de standruimte index van Hart (S %). Voor S % > 17.6 daalt de grondvlak-bijgroei met een niet-lineaire functie in S %. Het effect van yor bleek niet te schatten,Het effect van de dunning op de diameter na dunning is gemodelleerd met een gemodificeerd La Bastide-Faber model. Met alle modellen is een opstand projectie model gemaakt, waarmee de geme-ten opstandontwikkeling matig voorspeld werd.Er zijn opbrengsttabellen gemaakt met zes verschillende dunninggraden