Christian Ammer

Christian Ammer
Georg-August-Universität Göttingen | GAUG · Department of Silviculture and Forest Ecology of the Temperate Zones

About

296
Publications
150,593
Reads
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10,090
Citations
Additional affiliations
September 2007 - present
Georg-August-Universität Göttingen
Position
  • Professor (Full)
September 1996 - September 2001
Technische Universität München
Position
  • Research Assistant
April 1992 - September 1996
Ludwig-Maximilians-University of Munich
Position
  • Research Assistant

Publications

Publications (296)
Article
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Background The ability of overstory tree species to regenerate successfully is important for the preservation of tree species diversity and its associated flora and fauna. This study investigated forest regeneration dynamics in the Cat Ba National Park, a biodiversity hotspot in Vietnam. Data was collected from 90 sample plots (500 m ² ) and 450 su...
Article
Forest management has been shown to affect biodiversity, but the effects vary among taxa and studies. Due to their host-tree preferences, many saproxylic, i.e. deadwood-dependent, beetle species are likely affected by forest management via changes in tree species composition. However, further structural differences caused by forest management, such...
Article
Environmental filters – including those resulting from biotic interactions – play a crucial role during the assembly of ecological communities. The importance of scale has thereby been acknowledged but filters at different scales have rarely been quantified in relation to each other, although these hierarchically nested filters eventually determine...
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Plant species diversity and composition play crucial roles in many ecosystem services and are largely influenced by environmental conditions, as well as natural and/or anthropogenic disturbances. However, our knowledge of the drivers of plant species diversity and composition in the limestone forests of Vietnam, a hotspot of biodiversity, is limite...
Article
Increasing species diversity is considered a promising strategy to mitigate the negative impacts of global change on forests. However, the interactions between regional climate conditions and species-mixing effects on climate-growth relationships and drought resistance remain poorly documented. In this study, we investigated the patterns of species...
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The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we...
Article
Eine Arbeitsgruppe aus Vertreterinnen und Vertretern von Ressorteinrichtungen des Bundes und der Länder im Bereich Forstwirtschaft und Naturschutz stellt Thesen zur Entwicklung eines nationalen Biodiversitätsmonitorings im Wald vor. Ziel des Monitorings ist es, umfassende, repräsentative Informationen zur biologischen Vielfalt in den Wäldern Deutsc...
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The increasing disturbances in monocultures around the world are testimony to their instability under global change. Many studies have claimed that temporal stability of productivity increases with species richness, although the ecological fundaments have mainly been investigated through diversity experiments. To adequately manage forest ecosystems...
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Ecosystem functioning may directly or indirectly – via change in biodiversity – respond to land use. Dung removal is an important ecosystem function central for the decomposition of mammal faeces, including secondary seed dispersal and improved soil quality. Removal usually increases with dung beetle diversity and biomass. In forests, dung removal...
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Heterogeneity of structure can increase mechanical stability, stress resistance and resilience, biodiversity and many other functions and services of forest stands. That is why many silvicultural measures aim at enhancing structural diversity. However, the effectiveness and potential of structuring may depend on the site conditions. Here, we reveal...
Article
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Common myrtle (Myrtus communis L.) occurs in (semi-)arid areas of the Palearctic region where climate change, over-exploitation, and habitat destruction imperil its existence. The evergreen shrub is of great economic and ecological importance due to its pharmaceutical value, ornamental use, and its role in urban greening and habitat restoration ini...
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Der Deutsche Verband Forstlicher Forschungsanstalten (DVFFA) beleuchtet in seinem zweiten Beitrag der Serie „Fakten zum Thema: ...“ die Rolle der Wälder in Bezug zur Holznutzung.
Article
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In ihrem Leserbrief in der Ausgabe 4/2022 [5] zur DVFFAFaktenpublikation „Wälder und Klimaschutz“ [2] konstruieren die Autoren einen „Paradigmenwechsel“ in der deutschen Forst- und Holzwirtschaft hin zu einer auf reinen Nutzungsverzicht fokussierten Waldsicht, der angeblich durch die angesprochene DVFFA-Faktenpublikation unterstützt werde. Sind ihr...
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Effects of forest management on forest biodiversity have received increasing attention in both research and forestry practice. Despite advances in technology, monitoring of biodiversity remains time and cost-intensive and requires specific taxonomic expertise. In forest management, however, there is increasing interest and need to integrate biodive...
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Worldwide, forestry must face several challenges during the UN Decade on Ecosystem Restoration. The decline of biodiversity and ecosystem services, ongoing deforestation, climate change, and biological invasions must be mitigated with forest restoration and by applying sustainable forest management. Experiences with the integration of non-native tr...
Article
Just as the aboveground tree organs represent the interface between trees and the atmosphere, roots act as the interface between trees and the soil. In this function, roots take-up water and nutrients, facilitate interactions with soil microflora, anchor trees, and also contribute to the gross primary production of forests. However, in comparison t...
Article
The dynamics of forest structure influence forest ecosystem functions and are modified by forest management and natural disturbances. Here, we quantified the dynamics of stand structural complexity of differently managed and unmanaged European beech (Fagus sylvatica L.) forests. We determined changes of different aspects of stand structural complex...
Article
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Mixed cropping in short rotation coppice can be an alternative to monocultures. To design optimized mixtures, field trials are needed. Poplar, as an economically important and fast-growing species, and black locust, as a nitrogen-fixing species, are promising candidates for such studies. RNA sequencing (RNA-seq) was used to monitor effects of mixed...
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Short rotation coppice plays an important role for biomass production. Mixing fast‐growing tree species in short rotation coppices may lead to overyielding if the species have complementarity traits. The goal of this study is to analyze biomass yield of eight different poplar hybrids and black locust in mixed short rotation coppice after a rotation...
Article
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Aim The establishment of broadleaved - conifer mixtures has had positive effects on productivity. However, it is still not clear the degree to which belowground space occupation contributes to these effects and how root traits of the respective species differ between mixed and pure stands. Thus, the aim of this study was to examine how enrichment o...
Article
Warum sind Wälder wichtig für den Klimaschutz? Bäume nehmen bei der Fotosynthese Kohlendioxid (CO2) aus der Atmosphäre auf und legen einen Teil davon als Kohlenstoff in der Bestandesbiomasse fest (Abb. 1). Etwa 15 bis 30 % des Kohlenstoffs sind langfristig im Holz des oberirdischen Baumbestands gespeichert [8]. Auch Waldböden können CO2 langfristig...
Article
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1. Schall et al. (2020) assessed how a combination of different forest management systems in managed forest landscapes dominated by European beech may affect the biodiversity (alpha, beta and gamma) of 14 taxonomic groups. Current forest policy and nature conservation often demand for combining uneven-aged managed and unmanaged, set-aside for natur...
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Ungulate browsing has a major impact on the composition and structure of forests. Repeatedly conducted, large-scale regeneration inventories can monitor the extent of browsing pressure and its impacts on forest regeneration development. Based on the respective results, the necessity and extent of wildlife management activities such as hunting, fenc...
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Key message Mobile laser scanning and geometrical analysis revealed relationships between tree geometry and seed dispersal mechanism, latitude of origin, as well as growth. Abstract The structure and dynamics of a forest are defined by the architecture and growth patterns of its individual trees. In turn, tree architecture and growth result from t...
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Research on mixed forests has mostly focused on tree growth and productivity, or resistance and resilience in changing climate conditions, but only rarely on the effects of tree species mixing on timber quality. In particular, it is still unclear whether the numerous positive effects of mixed forests on productivity and stability come at the expens...
Article
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Short rotation coppices play an important role in providing biomass for energetic use. Mixing fast-growing tree species in short rotation coppices may show complementarity effects and increased yield. The aim of this study was to analyze the effect of species interaction in mixed short rotation coppices with fast-growing Populus spp.-hybrids and th...
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In Europe, the non-native Northern red oak (Quercus rubra L.) is widely recommended for future cultivation. However, outside its natural range, Northern red oak has to date been insufficiently studied both in terms of silviculture and genetics. To clarify this, we studied the architecture of 92 (pre-) dominant Northern red oak trees in five German...
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Unfortunately, there is information missing in Fig. 3. This figure represents all 4 poplar genotypes and black locust, which are differentiated by the letters (a) to (e).
Article
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Der Deutsche Verband Forstlicher Forschungsanstalten (DVFFA) stellt in seinem ersten Beitrag der Serie "Fakten zum Thema: ..." die Rolle der Wälder in Bezug zum Klimaschutz heraus.
Article
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Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provid...
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Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provid...
Article
Northern red oak wood is valuable for a variety of applications not only in its natural distribution range in North America, but also in Europe. Timber quality and stem diameter largely determine timber prices and respective uses. Silvicultural management is key to influencing tree growth and stem quality. In Germany, crop tree thinning is currentl...
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Land-use intensification poses major threats to biodiversity, such as to insect herbivore communities. The stability of these communities depends on interactions linking herbivores and host plants. How interaction network structure begets robustness, and thus stability, in different ecosystems and how network structure and robustness are altered al...
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The structural complexity of the understory layer of forests or shrub layer vegetation in open shrublands affects many ecosystem functions and services provided by these ecosystems. We investigated how the basal area of the overstory layer, annual and seasonal precipitation, annual mean temperature, as well as light availability affect the structur...
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Many organisms respond to anthropogenic environmental change through shifts in their phenology. In plants, flowering is largely driven by temperature, and therefore affected by climate change. However, on smaller scales climatic conditions are also influenced by other factors, including habitat structure. A group of plants with a particularly disti...
Preprint
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Background: Forest regeneration is decisive for future forest development and therefore of major concern to forest ecologists. The ability of overstory tree species to regenerate successfully is important for the preservation of tree species diversity and its associated flora and fauna. This study investigated forest regeneration dynamics in the Ca...
Article
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Automated species classification from 3D point clouds is still a challenge. It is, however, an important task for laser scanning-based forest inventory, ecosystem models, and to support forest management. Here, we tested the performance of an image classification approach based on convolutional neural networks (CNNs) with the aim to classify 3D poi...
Preprint
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The establishment of mixed forest stands can be seen as an option to improve soil nutrient conditions and to protect forest ecosystems from various impacts of climate change. Our study analyzed groups of pure mature European beech (Fagus sylvatica), Douglas fir (Pseudotsuga menziesii) and Norway spruce (Picea abies) stands as well as mixtures of be...
Article
Forest ecosystems are shaped by internal dynamics and external factors like forest management. A modified physical appearance of ecosystems may affect the short- and long-term provision of ecosystem goods and services (EG&S) from forests. Ecosystem functioning research provides powerful tools for both, the mechanistic description of ecosystem dynam...
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Background Forests perform various important ecosystem functions that contribute to ecosystem services. In many parts of the world, forest management has shifted from a focus on timber production to multi-purpose forestry, combining timber production with the supply of other forest ecosystem services. However, it is unclear which forest types provi...
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The complexity of forest structures plays a crucial role in regulating forest ecosystem functions and strongly influences biodiversity. Yet, knowledge of the global patterns and determinants of forest structural complexity remains scarce. Using a stand structural complexity index based on terrestrial laser scanning, we quantify the structural compl...
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• Reports of major losses in insect biodiversity have stimulated an increasing interest in temporal population changes. Existing datasets are often limited to a small number of study sites, few points in time, a narrow range of land‐use intensities and only some taxonomic groups, or they lack standardised sampling. While new monitoring programs hav...
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Motivation Trait data are fundamental to the quantitative description of plant form and function. Although root traits capture key dimensions related to plant responses to changing environmental conditions and effects on ecosystem processes, they have rarely been included in large‐scale comparative studies and global models. For instance, root trai...
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Significance Ecosystem services derive from ecosystem functions and rely on complex interactions among a diversity of organisms. By understanding the relationships between biodiversity, ecosystem functions, and the services humans receive from nature, we can anticipate how changes in land use will affect ecosystems and human wellbeing. We show that...
Article
Tree species-mixing has been suggested as one option to counteract the adverse effects of global change on tree mineral nutrition, yet the effect of mixing on nutrient availability remains poorly documented. We therefore analyzed the current foliar nutrient (N, P, K, Ca, Mg) quantities and ilr balances (isometric log transformed ratios between elem...
Chapter
Die Diskussion über nicht einheimische Arten (Neobiota) und deren Management in Umwelt- und Naturschutz ist häufig geprägt durch eine prinzipielle Ablehnung des Fremden. Hieraus leitet sich nicht selten eine Bekämpfung der Arten im Biotopmanagement und in der Ökosystemrenaturierung ab. In diesem Kapitel soll diese Problematik beleuchtet werden und...
Preprint
Reports of major losses in biodiversity have stimulated an increasing interest in temporal population changes, particularly in insects, which had received little attention in the past. Existing long-term datasets are often limited to a small number of study sites, few points in time, a narrow range of land-use intensities and only some taxonomic gr...
Preprint
Full-text available
Background The establishment of economically valuable conifers into a matrix of native broadleaved tree species may serve as model systems that combine economic interests and nature conservation. However, it is not clear which effects the enrichment by conifers has on soil properties. Methods Our study analyzed pure mature European beech ( Fagus s...
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In the original publication of the article the seventh author name was incorrectly published. The correct name is given in this correction.
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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The habitat heterogeneity hypothesis predicts that biodiversity increases with increasing habitat heterogeneity due to greater niche dimensionality. However, recent studies have reported that richness can decrease with high heterogeneity due to stochastic extinctions, creating trade-offs between area and heterogeneity. This suggests that greater co...
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Nutrient contents of soil organic matter in forests vary with regional differences in soil types and parent material, and can be modified by forest type and management intensity. Variation of organic carbon (OC)-to-nutrient ratios in soils supposedly alters microbial carbon and nutrient use efficiencies and the rates of OC-to-nutrient mineralizatio...
Article
Abstract (Paper is in German language!) Successful action in conservation calls for close exchange and effective feedback between science and practitioners at all levels. However, many examples and experiences indicate that this mutual exchange does not function optimally nor according to requirements. From the authors' point of view, there is a ne...
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Light is one of the most critical factors controlling tree survival and growth. Limited light availability induces phenotypic plasticity, thus enabling plants to adapt to suboptimal conditions. The plastic responses are species-specific and are thought to largely depend on species' shade tolerance. This study aims to add to existing research by try...
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Forest management greatly influences biodiversity across spatial scales. At the landscape scale, combining management systems that create different stand properties might promote biodiversity due to complementary species assemblages. In European beech forests, nature conservation and policy advocate a mixture of unmanaged (UNM) forests and uneven‐a...
Article
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One of the main goals of modern silviculture is to emulate the structural complexity of old-growth forests. In this context, it is of advantage to identify a target state of structural complexity at the stand level and to analyze the spatial characteristics that led to the desired complexity of forest structures in primary forest references. In thi...
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The threedimensional forest structure is an important driver of several ecosystem functions and services. Recent advancements in laser scanning technologies have set the path to measuring structural complexity directly from 3D point clouds. Here, we show that the box-dimension (Db) from fractal analysis, a measure of structural complexity, can be o...