Holger Gärtner

• Dr. rer. nat.; Dipl.-Geogr.
• Researcher at Swiss Federal Institute for Forest, Snow and Landscape Research

Permafrost and related landforms (rockglaciers) are widespread phenomena in alpine geosystems. In the context of changing environments due to the significant warming, there is a need for thorough monitoring and analyzing the complex responses of these cryospheric geosystems. Here, the first-time application of wood anatomical methods in this contex...

During recent decades, stable oxygen isotopes derived from tree-ring cellulose (δ¹⁸OTRC) have been frequently utilised as the baseline for palaeoclimatic reconstructions. In this context, numerous studies take advantage of the high sensitivity of trees close to their ecological distribution limit (high elevation or high latitudes). However, this in...

The ability of desert plants to adapt to future climate changes and maximize their water-use efficiency will determine their survival. This study uses wood anatomy and δ13C and δ18O isotope analyses to investigate how Moringa peregrina trees in the Egyptian desert have responded to the environment over the last 10 years. Our results show that M. pe...

Moringa peregrina (Forssk.) Fiori, one of 13 species of the Moringaceae family widely distributed throughout the dry tropics, has the potential to become one of the most economically important medicinal plants in Egypt. However, despite its tolerance for drought and heat, it is also threatened by increasing temperatures and decreasing precipitation...

The southern Mediterranean region, particularly North Africa, is a crucial area for biodiversity conservation. However, the impacts of climate change on plant species in this region are not well understood. Dendroecology, the study of tree rings, is a valuable technique for analyzing the effects of environmental changes on woody plants over time. I...

Plant anatomy is the branch of biology that is concerned with the study of the internal structure of plants and their parts. Accurate description and well knowledge of the anatomical ring-structure of the plants results in an accurate conclusion concerning internal physiological processes and the effects of environmental factors on them. This book...

Our understanding of wood anatomy and radial growth in tree roots remains very incomplete, particularly with respect to how ecological factors affect root growth at a relatively small spatial scale, i.e., within a single root system. Here, we compared root growth with and without trampling exposure on a hiking trail. We conducted a quantitative ana...

The rapidly collapsing glacial systems of the Alps produced a large number of melt-water lakes and mires after the Last Glacial Maximum (LGM) in the Late Glacial period. The Rhone-Aare-glacier system gave rise to large moorlands and lakes in the region of the Three Lakes Region of Western Switzerland. When moorlands are formed, they are efficient s...

Silvicultural interventions such as strip cuttings can change the resource availability of the edge trees. This may alter tree allometry, as light regime, water, and nutrient availability can change at the forest edge. Increased root growth may optimize resource uptake and/or enhance tree anchorage to withstand the altered wind regime. However, lit...

Norway spruce (Picea abies (L.) H. Karst.) is predicted to decrease its abundance in the Eastern Baltic region as a result of climatic changes, and this process is already explicit at the southern limit of species lowland distribution. Still, there are uncertainties about the growth potential of Norway spruce within the region due to the plasticity...

The formation of annual growth rings is an imperative requirement for studying the dendroecological potential of plant species. Little is known about the distinctness of growth rings in the wood of desert plants in Africa, particularly in southern Mediterranean regions. To fill this knowledge gap, we collected and anatomically analyzed about 300 pe...

Non-structural carbohydrates (NSC) reserves are crucial for trees to cope with weather extremes, thus to ensure their survival and ecological plasticity. The NSC reserves can depend on social status, suggesting uneven plasticity of trees at the stand level. In stemwood of Scots pine (Pinus sylvestris L.), which is a widespread and important species...

Dendrochronology has been applied around the world over decades to reconstruct historical geomorphological events and climatic conditions. Traditionally, this research has been conducted using trees (conifers as well as broad-leaved trees) but, in the last few decades, several shrub and dwarf shrub species have also been shown to be useful for dend...

Under changing climate, temporal and spatial stability (stationarity) of growth responses of trees to weather and climate, which has often been presumed without explicit testing, is crucial for prediction of productivity and sustainability of forests. However, considering evolutionary adaptation of tree populations to wide spatio-temporal ecologica...

Xylella fastidiosa (Xf) Wells, Raju et al., 1986 is a bacterium that causes plant diseases in the Americas. In Europe, it was first detected on the Salento Peninsula (Italy), where it was found to be associated with the olive quick decline syndrome. Here, we present the results of the first tree-ring study of infected and uninfected olive trees (Ol...

The impact of hiking in forested areas is one of the main factors affecting the condition of tree growth along hiking trails. Trampling causes common exposure of roots and quantification of the human impact on root radial growth and wood anatomy requires careful assessment. To accurately identify the radial growth changes in Pinus sylvestris roots,...

The quantitative assessment of wood anatomical traits offers important insights into those factors that shape tree growth. While it is known that conduit diameter, cell wall thickness, and wood density vary substantially between and within species, the interconnection between wood anatomical traits, tree-ring width, tree height and age, as well as...

Compression wood (CW) is a common tissue present in the trunk, branches and roots of mechanically stressed coniferous trees. Its main role is to increase the mechanical strength and regain the vertical orientation of a leaning stem. Compression wood is thought to influence the climate signal in different tree-ring measures. Hence trees containing C...

Assisted gene flow is advised as one of the most effective means to sustain the productivity of forests under warming climate via application of the provenances (genotypes) capable to utilize longer vegetation season. Nevertheless in the temperate and boreal zones, the extension of vegetation period also subjects trees to effects of frosts, which c...

Born 29th February 1936 near Bern, Switzerland, Fritz Hans Schweingruber worked as a teacher until 1965, obtained a PhD in botany from the University of Basel in 1972 (where he also obtained a Professorship in 1976), and started his lifelong career at the Swiss Federal Research Institute WSL in Birmensdorf right afterwards. Fritz developed a dendro...

Das Berner Seeland umfasst die in einem Dreieck zwischen Neuenburger-, Murten- und Bielersee eingebettete Senke am Jurasüdfuss. Noch vor 160 Jahren prägten Überschwemmungen, Armut und Krankheiten (Malaria) das Leben der Bevölkerung. Die erste Juragewässerkorrektion (1868 - 1897) verbesserte die Situation für die lokale Bevölkerung entscheidend und...

X‐ray microdensitometry on annually resolved tree‐ring samples has gained an exceptional position in last‐millennium paleoclimatology through the maximum latewood density (MXD) parameter, but also increasingly through other density parameters. For 50 years, X‐ray based measurement techniques have been the de facto standard. However, studies report...

The efficiency of water use and transport are among the main factors affecting competitiveness, growth, and distribution of trees under warming climate. The phenotypical and genetic plasticity of tree populations is considered as an indicator of their adaptive capacity under changing environment. Climatic changes are expected to affect growth of Sc...

Knowledge on the ecology of tree species in both their native and introduced range can increase the understanding of their successful establishment and spread outside the native range. Here, we analysed radial growth patterns of Ailanthus altissima (Mill.) Swingle in two sites in its native range in eastern China and in two sites in the introduced...

Disturbance of high elevation Norway spruce stands, as due to strip cutting, results in a change in resource availability for edge trees and may shift their biomass allocation towards above- or belowground structures. Changes of wind exposure may also stimulate root growth in order to stabilize the edge trees. Neglecting alterations in belowground...

The annual growth and wood characteristics of tree species at southern Mediterranean countries, and its relationship with climate variables are recently two important topics for the researchers in this region. Although Moringa peregrina (Forssk.) Fiori is a key species in Africa due to its medicinal and economic values (e.g. as fuel, food and water...

Die Bilder grossflächig brauner Laubbäume in weiten Teilen der Schweiz sowie Zentraleuropas im Frühsommer 2018 sind uns noch sehr präsent. Diese um rund drei Monate verfrühte Herbstverfärbung der Wälder war das Resultat der extremen Hitze und langanhaltenden Dürre. Auch wenn das Ausmass und die Sichtbarkeit der Schäden in Wald und Landwirtschaft 20...

A spatiotemporal reconstruction of slope movements on the edge of Lake Lucerne near the municipality of Horw, canton of Lucerne, is presented. The reconstruction was realized by analyzing growth reactions of beech ( Fagus sylvatica L.) and fir ( Abies alba Mill.) trees growing on this slope. Before dendrochronological sampling, a detailed geomorpho...

Plants essentially contribute to the strength of soil and, in particular, steep slopes susceptible to erosion and shallow landslides. The corresponding functions of vegetation significantly control processes above and below ground such as interception, evapo-transpiration, soil aggregation and root reinforcement. Either way, they are all correlated...

Erkenntnisse aus der Trockenheit 2018 für die zukünftige Waldentwicklung Eine ausgeprägte Niederschlagsarmut im Sommer und Herbst des Jahres 2018 führte in grossen Teilen der Schweiz, insbesondere im nordöstlichen Mittelland, zu einer verbreiteten und lang anhaltenden Trockenheit. Die unmittelbaren und mittelfristigen Auswirkungen des trockenen Som...

The use of automated techniques for image analysis of microscopic wood specimens together with new procedures for the preparation of stained xylem tissue support the use of quantitative wood anatomy. These techniques and procedures are especially useful in the studies of retrospective analysis of xylem phenology, reaction(s) of trees to stressful c...

Key message The combination of terrestrial laser scans and tree-ring data allows for a highly precise reconstruction of annual stem growth, and thus complex tree-growth analyses independent of species and site characteristics. Abstract Reliable carbon pools data are needed to quantify the carbon stored in ecosystems and for effective forest manage...

Berenty Reserve, a fully protected gallery forest beside the Mandrare River is renowned for its lemurs, but the continuous canopy of the main forest is shrinking, fragmenting and degrading. The aim of this study, before any restoration can be considered, is to investigate why canopy-cover is declining and define the forest’s vegetation status and c...

The kinetic energy of landslides highly influences the growth structure of tree stems and thus causes the development of reaction wood in the xylem. Most studies focus on assessing the reaction wood development in conifers. However, the response of hardwood species (e.g. beech - Fagus sylvatica L. and birch - Betula pendula L.) on external mechanic...

Paleoclimatic evidence is necessary to place the current warming and drying of the western Mediterranean basin in a long-term perspective of natural climate variability. Annually resolved and absolutely dated temperature proxies south of the European Alps that extend back into medieval times are, however, mainly limited to measurements of maximum l...

The TRACE 2015 conference was held on 20-23 May 2015 in Sevilla, Spain. This was the first TRACE in the Iberian Peninsula. It was organized by the University Pablo de Olavide (UPO) and the Association for Tree-ring Research (ATR), in collaboration with Pyrenean Institute of Ecology-Spanish National Research Council (IPE-CSIC), University of Barcelo...

Steep vegetation-free talus slopes in high mountain environments are prone to superficial slope failures and surface erosion. Eco-engineering measures can reduce slope instabilities and thus contribute to risk mitigation. In a field experiment, we established mycorrhizal and non-mycorrhizal research plots and determined their biophysical contributi...

Wood anatomical features may be visible on the microscopic as well as on the macroscopic scale. While the former can often be quantified by detailed wood anatomical analyses, the latter are often treated as qualitative features or as binary variables (present/absent). Macroscopic tree-ring features can be quantified in terms of frequency, intensity...

Wood anatomical features may be visible on the microscopic as well as on the macroscopic scale. While the former can often be quantified by detailed wood anatomical analyses, the latter are often treated as qualitative features or as binary variables (present/absent). Macroscopic tree-ring features can be quantified in terms of frequency, intensity...

This publication is a result of the 14th TRACE conference (Tree Rings in Archaeology, Climatology and Ecology) organized by the Department Physical, Chemical and Natural Systems of the University Pablo de Olavide (UPO) and the Association for Tree-ring Research (ATR), in collaboration with Pyrenean Institute of Ecology-Spanish National Research Cou...

Tourism impact, such as trampling erosion in protected forested areas, is one of the main concerns for land managers. The impact by trampling is easily visible at locations of highly concentrated tourist traffic, such as on hiking trails. Trampling activity together with natural geomorphic processes is responsible for the exposure of roots on trail...

The analysis of anatomical variations within annual rings of trees and shrubs has great potential for reconstructing past environmental conditions. However, detailed wood anatomical analysis has rarely been applied to long-term reconstructions mostly because of methodological constraints and time-consuming procedures of data collection. We develope...

ABSTRACT Based on the Reichert Om E microtome a more sophisticated, nevertheless solely mechanically operated microtome was developed enabling to section specimens of various forms and sizes. the materials used and the special construction of the microtome resulted in a higher stability of the moving parts whilst simultaneously reducing weight. As...

Permafrost is a common feature in high mountain ecosystems. Even though its main distribution is restricted to areas above timberline, there are several sites where permafrost occurs in lower elevations. Those ecological " coldspots " are characterized by a patchy distribution of relative warm ice lenses in the near subsurface due to multifaceted p...

Dendroecological research uses information stored in tree rings to understand how single trees and even entire forest ecosystems responded to environmental changes and to finally reconstruct such changes. This is done by analyzing growth variations back in time and correlating various plant-specific parameters to (for example) temperature records....

Steep erosion‐prone and vegetation‐free slopes are widespread in alpine areas and are often discussed since they have a high socio‐economic damage potential. We present an eco‐engineering approach to test whether a mycorrhizal inoculum improves the establishment of hedge brush layers and in turn soil structural stability on a steep, coarse‐grained...

Key message An outbreak of the western spruce budworm temporarily modifies cellular wood anatomy of stem wood in natural and mature Douglas-fir stands impacting wood quality properties. Abstract Western spruce budworm (Choristoneura occidentalis Freeman) is a widespread and destructive defoliator of commercially important coniferous forests in w...

The observation and monitoring of the aboveground plant development is a common practice in eco-engineering to estimate the plant's influence on the stabilization process. In contrast to this aboveground " sphere " , the near subsurface is invisible and therefore difficult to address. To get an impression of the near subsurface and to model slope s...

The date of the volcanic eruption of Santorini that caused extensive damage to Minoan Crete has been controversial since the 1980s. Some have placed the event in the late seventeenth century BC. Others have made the case for a younger date of around 1500 BC. A recent contribution to that controversy has been the dating of an olive tree branch prese...

The date of the volcanic eruption of Santorini that caused extensive damage toMinoan Crete has been controversial since the 1980s. Some have placed the event in the late seventeenth century BC. Others have made the case for a younger date of around 1500 BC. A recent contribution to that controversy has been the dating of an olive tree branch preser...

QuestionsTo what extent do Mediterranean dwarf shrub species of phrygana and mountain habitats form distinct annual growth rings and are therefore suitable for further studies on the dynamics of phrygana? How are growth ring numbers and species turnover of dwarf shrub communities distributed along an altitudinal gradient of ca. 1800m? Is the age di...

A method based on dendrochronology was developed to analyse the spatial and temporal variability of land-slide activity as an alternative and complement to methods such as field monitoring of landslide relief, aerial-photography, and remote sensing. The method involves a feature of wood anatomy, tree-ring eccen-tricity, which is used in the dating...

Current climatic conditions and the occurrence of discontinuous and sporadic permafrost in the Alps result in a low turnover rate and therefore accumulation of organic matter (OM) in soils. Alpine soils are thus highly sensitive to global warming that potentially promotes the mineralisation of soil organic matter (SOM). This process might in-crease...

You can order the book by sending an email to the printing house. (Price: 22.- Euro plus shipping) This booklet results from the experiences of teaching “Wood Anatomy of Tree Rings” courses, during which we realized that there is a deficit regarding available information on the practical aspect of wood anatomical work. We aim to present basic prepa...

Arctic ecosystems are important carbon sinks. Increasing temperatures in these regions might stimulate soil carbon release. Evidence suggests that deciduous shrubs might counteract these carbon losses because they positively respond to increasing temperature, but their role in ecosystem carbon budgets remains uncertain. Many studies dealing with la...

Global warming is anticipated to result in an increase of heavy precipitation events. In vegetation-free, steep Alpine areas intense rain fall events have distinct influences on erosional processes on slopes. These processes and (shallow) mass movements are directly linked with torrential rain falls, and for this lead to high erosion rates in those...

Geomorphology, a subfield of geosciences, deals with landforms and related processes and reveals the complex interrelations between the origin of landform and the dynamics of its alteration. In this regard, the dating and reconstruction of past geomorphic processes is of special interest to reveal landform development and predict future changes in...

Arctic environments, where surface temperatures increase and sea ice cover and permafrost depth decrease, are very sensitive to even slight climatic variations. Placing recent environmental change of the high-northern latitudes in a long-term context is, however, complicated by too short meteorological observations and too few proxy records. Driftw...

Olive trees are a classic component of Mediterranean environments and some of them are known historically to be very old. In order to evaluate the possibility to use olive tree-rings for dendrochronology, we examined by various methods the reliability of olive tree-rings identification. Dendrochronological analyses of olive trees growing on the Aeg...

Plasticity of xylem architecture can be a species specific strategy to reduce vul-nerability to climate change. To study how the evergreen shrub Erica arborea regulates its xylem at different time scales as a response to climatic variability, we compared time series of annual xylem traits such as ring-width (growth), vessel size (hydraulic diameter...

Ring width of a given year can be highly variable throughout the cross section of a stem. This is especially true for roots. Therefore, the entire circumference of tree rings is often needed for studies focusing on specific reactions of individual trees on certain environmental conditions. Also, ring reconstructions are of interest for biomass calc...

Dynamic root-development models are indispensable for biomechanical and biomass allocation studies, and also play an important role in understanding slope stability. There are few root-development models in the literature, and there is a specific lack of dynamic models. Therefore, the aim of this study is to develop a 3D growth-development model fo...

Celem badań było zweryfikowanie przydatności dekoncentryczności przyrostu radialnego drzew oraz opracowanych wskaźników (indeks procentowy) w analizie ruchów osuwiskowych na przykładzie osuwiska Keprnícký (Hrubý Jeseník, Sudety Wschodnie, Republika Czeska). Na badanym osuwisku próby pobrano z 42 drzew, a na pobliskim stoku referencyjnym z 12 drzew...

The 10th TRACE conference (Tree Rings in Archaeology, Climatology and Ecology) was organized by the Institut National de la Recherche Agronomique (INRA) - Centre d'Orléans Unité Amélioration, Génétique et Physiologie Forestières, on May 11th – 14th 2011 in the “Muséum des Sciences Naturelles” in Orléans, France. TRACE is an initiative of the ‘Assoc...

A microtome designed for the surface preparation of entire increment cores allows cutting plane surfaces on cores up to a length of 40cm. Compared to the common sanding procedure, the wood cells of the annual rings remain open, not filled with swarf, and the cell walls are smooth and hence clearly visible. This article aims at describing the functi...

In times of global change biomass calculations and the carbon cycle is gaining in importance. Forests act as carbon sinks and hence, play a crucial role in worlds and forests carbon budgets. Unfortunately, growth models and biomass calculations existing so far mainly concentrate on the above-ground part of trees. For this reason, the aim of the pre...

Explorative wood anatomical analysis was conducted on a Castanea sativa stand in southern Switzerland, where a moderate-intensity surface fire burned in April 1997. Cross-sections were sampled at multiple heights from 20 scarred shoots, 20 apparently intact shoots, along with cores taken from 20 reference trees outside the fire area. Thin sections...

Recently, the Mediterranean region has experienced unprecedented drought. Climate models continue to predict an increase in drought frequency and duration, which increases the importance of quantifying the response of already drought-tolerant Mediterranean plants to increased drought. We examined the wood anatomy and dendroecological features of a...

Variability in xylem anatomy is of interest to plant scientists because of the role water transport plays in plant performance and survival. Insights into plant adjustments to changing environmental conditions have mainly been obtained through structural and functional comparative studies between taxa or within taxa on contrasting sites or along en...

Details about the spatiotemporal development of root systems and their influence on ring-width variations in tree stems are still unknown. Furthermore, their size, spread and architecture play an important role in studying tree stability and their stabilizing effect on slopes. A major problem in this regard is the detailed 3D-data acquisition and m...

Wounding experiments, imitating the impact of geomorphic processes such as rock fall, were performed on Larix decidua mill. and Picea abies (L.) Karst., before the beginning and at the end of the growing season. This was done to evaluate the timing and spread of traumatic rows of resin ducts (TDs) as a result of wounding during dormancy, when most...