Jan Altman

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Verified

Jan verified their affiliation via an institutional email.

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• Ph.D.
• Researcher at Czech Academy of Sciences, Institute of Botany

Significance Long-term variability in tropical cyclone (TC) activity is of high relevance for the development of adaptation and mitigation strategies; however, our current knowledge is based mostly on short-term records, with strong discrepancies among various datasets. We used tree-ring records of past forest disturbances to show rapid increases i...

With global warming, tropical cyclones (TCs) are moving to northern latitudes with devastating effects on boreal forests and significant ecological and socioeconomic consequences in the northern hemisphere. Recently, TCs disturbances have been documented in the northern temperate and even the southern boreal forest zone. Here we report and quantify...

Tropical cyclones (TCs) are one of the most devastating storm systems with high socioeconomic impacts around the world. The drivers of long-term changes in TC frequency and intensity, including the recent global climatic changes, are, however, poorly understood due to short instrumental measurements and a lack of accurate proxy records. Here we pre...

Increasing tropical cyclone (TC) pressure on temperate forests is inevitable under the recent global increase of the intensity and poleward migration of TCs. However, the long-term effects of TCs on large-scale structure and diversity of temperate forests remain unclear. Here, we aim to ascertain the legacy of TCs on forest structure and tree speci...

Forest succession, pivotal for biodiversity restoration after disturbance, lacks comprehensive comparisons among different taxa to elucidate mechanisms driving spatiotemporal diversity changes across trophic levels. While forest succession is generally understood, knowledge of multi-taxon succession in lowland temperate broadleaf forests is limited...

Climate warming stimulates growth and reproduction in cold‐adapted plants but also leads to extreme weather events that may hinder their performance. We examined these predictions in the cold‐arid Himalayan subnival zone at 5900 m, where unprecedented warming and extreme snowfalls occurred over the past three decades. We collected 205 individuals o...

The poleward expansion of tropical cyclones (TCs) inevitably triggers unprecedented ecological consequences for cool‐temperate and boreal forests, including shifts in species distribution, global carbon dynamics, or forest policies. However, our current understanding of the impact of TCs' expansion into new regions is limited and lacks attention by...

Plant functional traits are fundamental to ecosystem dynamics and Earth system processes, but their global characterization is limited by the availability of field surveys and trait measurements. Recent expansions in biodiversity data aggregation, including large collections of vegetation surveys, citizen science observations, and trait measurement...

The strategies of Norway spruce [Picea abies (L.) Karst.] to increasing atmospheric CO2 concentration (Ca) are not entirely clear. Here, we reconstructed centennial trajectories of leaf internal CO2 concentration (Ci) and intrinsic water-use efficiency (WUEi) from the amount of ¹³C in tree-ring cellulose. We collected 57 cores across elevations, so...

Plants store nonstructural carbohydrates (NSCs) like starch, fructans and soluble sugars to support metabolism, stress tolerance and defence during low photosynthesis, ultimately influencing their growth and longevity. However, the relationship between NSC composition and growth or persistence in wild plants remains unclear. This study explores tra...

Background and Aims Understanding interspecific differences in plant growth rates and their internal and external drivers is key to predicting species responses to ongoing environmental changes. Annual growth rates vary among plants based on their ecological preferences, growth forms, ecophysiological adaptations, and evolutionary history. However,...

Accurate assessment of forest losses and evaluation of future damage risks are crucial for effective forest management and conservation, particularly as global warming intensifies natural disturbance agents. This study introduces a novel approach combining convolutional neural networks (CNNs) with Random Forest (RF) machine learning classifiers to...

Aim Climate variations within the stadial–interstadial cycles drive shifts in the distribution of forest dominants. This study examines how climate dynamic alters the distribution ranges of two boreal and one cold‐temperate Abies species dominating in Northeast Asia. Location Northeast Asia: China, Japan, Korea and Russia. Taxon Abies nephrolepis...

Understanding mechanisms driving tropical tree growth is essential for comprehending carbon sequestration and predicting the future of tropical forests amid rapid deforestation. We conducted a natural experiment in Mount Cameroon to identify climatic factors limiting diurnal and seasonal growth in dominant tree species across a 2200-m elevation gra...

Excessive tree mortality is a global concern and remains poorly understood as it is a complex phenomenon. We lack global and temporally continuous coverage on tree mortality data. Ground-based observations on tree mortality, e.g., derived from national inventories, are very sparse, not standardized and not spatially explicit. Earth observation data...

The Himalayas are undergoing significant changes in temperature and moisture availability due to global climate change. Understanding how these changes affect tree growth is critical for conserving and managing this biodiverse region. To investigate the growth-limiting climatic factors, we collected tree-ring data from Abies pindrow old-growth moun...

Understanding mechanisms stabilizing ecosystem functions, such as primary production, is crucial for forecasting global environmental responses. While biological diversity is expected to enhance stability through compensatory reactions to environmental changes, empirical evidence is lacking, especially in old‐growth forests vital for biodiversity c...

Increases of temperatures and atmospheric CO2 concentration influence the growth performance of trees worldwide. The direction and intensity of tree growth and physiological responses to changing climate do, however, vary according to environmental conditions. Here we present complex, long-term, tree-physiological responses to unprecedented tempera...

Understanding alpine plants’ growth dynamics and responses to warming is essential for predicting climate change impacts on mountain ecosystems. Here, we examine growth determinants in the alpine cushion plant Silene acaulis in the Swiss Alps, exploring ontogeny, elevation, and climate influences. We collected 40 Silene individuals and 159 individu...

Forests are undergoing increasing risks of drought-induced tree mortality. Species replacement patterns following mortality may have a significant impact on the global carbon cycle. Among major hardwoods, deciduous oaks (Quercus spp.) are increasingly reported as replacing dying conifers across the Northern Hemisphere. Yet, our knowledge on the gro...

The poleward migration of tropical cyclones (TCs) inevitably triggers unprecedented ecological consequences for cool-temperate and boreal forests, including shifts in species distribution, global carbon dynamics, or forest policies. However, our current understanding of the impact of TCs’ expansion into new regions is limited and lacks attention by...

Background and Aims Understanding anatomical variations across plant phylogenies and environmental gradients is vital for comprehending plant evolution and adaptation. Previous studies on tropical woody plants have paid limited attention to quantitative differences in major xylem tissues, which serve specific roles in mechanical support (fibres), c...

Background and Aims Understanding biomass allocation among plant organs is crucial for comprehending plant growth optimization, survival and responses to global change drivers. Yet, mechanisms governing mass allocation in vascular plants from extreme elevations exposed to cold and drought stresses remain poorly understood. Methodology We analyzed...

Temperature is a fundamental driver of species distribution and ecosystem functioning. Yet, our knowledge of the microclimatic conditions experienced by organisms inside tropical forests remains limited. This is because ecological studies often rely on coarse-gridded temperature estimates representing the conditions at 2 m height in an open-air env...

Temperate forests are undergoing significant transformations due to the influence of climate change, including varying responses of different tree species to increasing temperature and drought severity. To comprehensively understand the full range of growth responses, representative datasets spanning extensive site and climatic gradients are essent...

The vegetation of the Kuril Islands remains insufficiently explored due to their remote location and harsh environment. Understanding the factors that influence vegetation distribution in this extensive volcanic chain of islands, spanning over a thousand kilometers, is important for global biogeography. Our paper presents the first vegetation map o...

Global warming may lead to increased tree growth but also reduced tree performance due to increased moisture stress. Under what conditions these conflicting responses occur remains uncertain, especially when growth is controlled by different climatic factors throughout the year. Here, we investigate the growth response of Tsuga dumosa, a Himalayan...

Boreal forests represent an important carbon sink and, therefore, significantly contribute to climate change mitigation. Tree-ring width series of boreal species reflect climate variation at the moment of tree-ring formation but also lagged climatic effects from dormancy preceding tree-ring formation and antecedent growing seasons. However, little...

Ongoing climate change can have varying impacts on tree growth within the growing season and across their elevation ranges, with important implications for forest ecosystem functions and services. However, our knowledge of these effects on climate-sensitive Himalayan forests is still limited. Here, we explore the elevational changes in climatic fac...

The use of drone-borne imagery for tree recognition holds high potential in forestry and ecological studies. Accurate species identification and crown delineation are essential for tasks such as species mapping and ecological assessments. In this study, we compared the results of tree crown recognition across three neural networks using high-resolu...

Plant lifespan has important evolutionary, physiological, and ecological implications related to population persistence, community stability, and resilience to ongoing environmental change impacts. Although biologists have long been puzzled over the extraordinary variation in plant lifespan and its causes, our understanding of interspe-cific variab...

Aim Theoretical, experimental and observational studies have shown that biodiversity–ecosystem functioning (BEF) relationships are influenced by functional community structure through two mutually non‐exclusive mechanisms: (1) the dominance effect (which relates to the traits of the dominant species); and (2) the niche partitioning effect [which re...

It is critical to understand the ecological processes of forest dynamics by identifying past forest disturbances to take appropriate management actions. Tree-rings are commonly used for this purpose due to their reliability and accuracy. Here, we used a network of ring-width data distributed along a broad ecological gradient for the spatiotemporal...

Plant lifespan has important evolutionary, physiological, and ecological implications related to population persistence, community stability, and resilience to ongoing environmental change impacts. Although biologists have long puzzled over the extraordinary variation in plant lifespan and its causes, our understanding of interspecific variability...

Understanding multiple environmental drivers governing tropical organisms' distribution and ecological niches is crucial for predicting their responses to ongoing rapid deforestation. While macroclimatic effects via energy and water availability are well predicted, less is known about locally modulating factors such as canopy structure, light and e...

The longleaf pine ( Pinus palustris Mill.) and related ecosystem is an icon of the southeastern United States (US). Once covering an estimated 37 million ha from Texas to Florida to Virginia, the near-extirpation of, and subsequent restoration efforts for, the species has been well-documented over the past ca. 100 years. Although longleaf pine is o...

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...

Soil phototrophic microbes play key roles in many ecosystem functions, including nutrient cycling, water absorption and retention, substrate weathering and soil stabilization, as well as colonization and persistence of other organisms. Knowledge about the diversity and biomass of soil phototrophs remains limited, especially in tropical forests and...

Invasions of alien plants pose a serious threat to native biodiversity and ecosystem processes. Forests are considered more resistant to invasion due to limited light availability in understories. However, disturbance and abiotic stress may open tree canopies and promote invasion. Their combined effects together with the resistance of resident spec...

Nonstructural carbohydrates (NSC) are the crucial components of plant metabolism, and NSC dynamics provide essential information on plant carbon balance, which usually changes toward the distribution limits of plants. NSC have been extensively used to study the elevational limit in trees all around the world. For alpine herbs, which occupy vast are...

Knowledge of forest recovery processes after severe disturbances, such as tropical cyclones, is essential for understanding the mechanisms maintaining forest diversity and ecosystem functioning. However, studies examining the impact of tropical cyclones on forest dynamics are still rare, especially in Northeast Asia. Here, we explore the complex re...

Tropical cyclones (TCs) are common disturbance agents in tropical and subtropical latitudes. With global warming, TCs began to move to northern latitudes, with devastating effects on boreal forests. However, it remains unclear where and when these extraordinary events occur and how they affect forest structure and ecosystem functioning. Hence knowi...

Aim Species on islands are at high risk of extinction due to environmental changes, including global warming, land‐use alterations and invasions. At local scales, extinctions can be offset by strategies promoting in situ persistence. We explored how persistence‐related traits of plants—that is, linked to belowground resource conservation, growth, s...

Aim: Understanding the variation in community composition and species abundances (i.e., β-diversity) is at the heart of community ecology. A common approach to examine β-diversity is to evaluate directional variation in community composition by measuring the decay in the similarity among pairs of communities along spatial or environmental distance...

Aim Untangling multiple drivers influencing biodiversity along elevation gradients is necessary for predicting the consequences of climate change on mountain communities. We examine the direct and indirect effects of macroclimate, edaphic conditions, fire frequency and putative biotic interactions on species richness and abundance of co‐occurring p...

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we...

Current climate warming and extended droughts have major impacts on plant performance, with consequences for biodiversity and ecosystem functioning. However, unlike in trees, little is known about species-specific responses in grassland plants and the role of their different life histories in mitigating climate change impacts. We studied the climat...

Background and Aims Petioles are important plant organs connecting stems with leaf blades and affecting light-harvesting ability of the leaf as well as transport of water, nutrients and biochemical signals. Despite the high diversity in petiole size, shape and anatomy, little information is available about their structural adaptations across evolut...

Tropical cyclones (TCs) are common disturbance agents in tropical and subtropical latitudes. With global warming, TCs began to move to northern latitudes, with devastating effects on boreal forests. However, it remains unclear where and when these extraordinary events occur and how they affect forest structure and ecosystem functioning. Hence knowi...

Invasive, alien trees threaten native biodiversity, but detailed information about the patterns and mechanisms of diversity loss remain unknown. We explored the impact of an invasive tree on vascular plants and saproxylic beetles. We compared their species richness, community composition, and selected biological characteristics between stands of in...

Species coexistence is a result of biotic interactions, environmental and historical conditions. The Janzen-Connell hypothesis assumes that conspecific negative density dependence (CNDD) is one of the local processes maintaining high species diversity by decreasing population growth rates at high densities. However, the contribution of CNDD to spec...

Disturbances play a fundamental role in shaping forest communities. It is therefore important to accurately quantify their frequency and magnitude in forest ecosystems. Tree-ring series are commonly used for relatively accurate detection of past disturbances. Currently, several dendroecological techniques exist that enable the detection of disturba...

Aim Plant growth and phenology respond plastically to changing climatic conditions in both space and time. Species‐specific levels of growth plasticity determine biogeographical patterns and the adaptive capacity of species to climate change. However, a direct assessment of spatial and temporal variability in radial growth dynamics is complicated,...

1. Species extinction risk at local scales can be partially offset by strategies promoting in-situ persistence. We explored how persistence-related traits of clonal and non-clonal plants in temperate dry grasslands respond intra- and interspecifically to variation in environmental conditions (soil, climate) and insularity. 2. We focused on edaphic...

Macrophytes have often been considered as a prospective tool for the elimination of cyanobacterial bloom, because they may produce chemical compounds that outcompete bloom-forming cyanobacteria. However, a comprehensive, unbiased overview of evidence to support this is missing. Moreover, studies into the effects of individual macrophyte species hav...

Climate reconstructions provide important insight into past climate variability and help us to understand the large-scale climate drivers and impact of climate change. However, our knowledge about long-term year-to-year climate variability is still limited due to the lack of high-resolution reconstructions. Here, we present the first precipitation...

The knowledge of past tropical cyclone (TC) activity is vital to understanding patterns of current and future TCs and how they will impact society, infrastructure, and the natural system. Various historical, biological, and geological proxies are commonly used to reconstruct TC behavior; however, these records vary significantly in their temporal r...

The Canary Islands, an archipelago east of Morocco's Atlantic coast, present steep altitudinal gradients covering various climatic zones from hot deserts to subalpine Mediterranean, passing through fog-influenced cloud forests. Unlike the majority of the Canarian flora, Pinus canariensis grow along most of these gradients, allowing the study of pla...

Petioles are important plant organs connecting stems with leaf blades and affecting light-harvesting leaf ability as well as transport of water, nutrient and biochemical signals. Despite petiole's high diversity in size, shape and anatomical settings, little information is available about their structural adaptations across evolutionary lineages an...

The Canary Islands, an archipelago east of Morocco's Atlantic coast, present steep altitudinal gradients covering various climatic zones from hot deserts to subalpine Mediterranean, passing through fog-influenced cloud forests. Unlike the majority of the Canarian flora, Pinus canariensis grow along most of these gradients, allowing the study of pla...

Research in environmental science relies heavily on global climatic grids derived from estimates of air temperature at around 2 meter above ground1-3. These climatic grids however fail to reflect conditions near and below the soil surface, where critical ecosystem functions such as soil carbon storage are controlled and most biodiversity resides4-8...

Recent climate warming is associated with the increasing magnitude and frequency of extreme events, including heatwaves and drought periods worldwide. Such events can have major effects on the species composition of plant communities, hence on biodiversity and ecosystem functioning. Here we studied responses of Central European dry grassland plants...

Mechanisms structuring tropical communities are still under‐studied, especially in Afrotropical rainforests. Although insect herbivores are considered to depend on plant diversity, we hypothesized that vegetation structure, together with other microhabitat characteristics, can be more important for some insects. Here, we compared habitat associatio...

Accurate remote detection of various forest disturbances is a challenge in global environmental monitoring. Addressing this issue is crucial for forest health assessment, planning salvage logging operations, modeling stand dynamics, and estimating forest carbon stocks and uptake. Substantial progress on this problem has been achieved owing to the r...

Aim Understanding how natural forest disturbances control tree regeneration is key to predicting the consequences of globally accelerating forest diebacks on carbon stocks and forest biodiversity. Tropical cyclones (TCs) are important drivers of forest dynamics in Eastern Asia, and it is predicted that their importance will increase. However, littl...

Very high resolution satellite imageries provide an excellent foundation for precise mapping of plant communities and even single plants. We aim to perform individual tree recognition on the basis of very high resolution RGB (red, green, blue) satellite images using deep learning approaches for northern temperate mixed forests in the Primorsky Regi...

Natural disturbances are essential for tropical forests biodiversity. In the Afrotropics, megaherbivores have played a key role before their recent decline. Contrastingly to savanna elephants, forest elephants' impact on ecosystems remains poorly studied. Few decades ago, forests on Mount Cameroon were divided by lava flows, not being crossed by a...

Current analyses and predictions of spatially‐explicit patterns and processes in ecology most often rely on climate data interpolated from standardized weather stations. This interpolated climate data represents long‐term average thermal conditions at coarse spatial resolutions only. Hence, many climate‐forcing factors that operate at fine spatiote...

The impact of climatic change on forest ecosystems has received considerable attention, but our understanding of the modulation of this impact by elevational differences and by species interaction is still limited. Here, we analyse tree-ring-based growth-climate relationships for two dominant tree species along an 800-m elevational gradient on Jeju...

Understanding how climate influences plant reproduction and growth at contrasting range limits is crucial for predicting how species' ranges may shift in response to ongoing climate change. Trees and shrubs have shown warming‐induced increases in performance at upper elevation limits but reduced performance at lower distributional limits due to war...

Understanding how diversity affects ecosystem stability is crucial for predicting the consequences of continued habitat and biodiversity loss on ecosystem functions and services. Long‐term productivity stability in plant communities is often associated with greater species, phylogenetic or functional diversity, more complex size and age structures,...

Disturbances play an important role in forest dynamics. The determination of long-term spatiotemporal characteristics of disturbance regimes is essential for understanding forest dynamics and its shifts under global changes. Tree rings are known to provide detailed insight into both temporal and spatial patterns of forest disturbance history. One o...

Natural disturbances are essential for dynamics of tropical rainforests, contributing to their tremendous biodiversity. In the Afrotropical rainforests, megaherbivores have played a key role before their recent decline. Although the influence of savanna elephants on ecosystems has been documented, their close relatives, forest elephants, remain poo...

Here, we present precipitation reconstructions based on tree rings from Pinus koraiensis (Korean pine) from three sites placed along latitudinal (330 km) gradient in Sikhote-Alin mountains, Russian Far East. The tree-ring width chronologies were built using standard tree-ring procedures. We reconstructed the April–June precipitation for the souther...

Current analyses and predictions of spatially‐explicit patterns and processes in ecology most often rely on climate data interpolated from standardized weather stations. This interpolated climate data represents long‐term average thermal conditions at coarse spatial resolutions only. Hence, many climate‐forcing factors that operate at fine spatiote...

The precise demarcation between earlywood and latewood is important for the detailed analysis of intra-annual tree ring features. Different techniques based on visual assessment, wood anatomy analysis and X-ray densitometry have been developed and are currently used for this purpose. Depending on the chosen method, tree species and environmental co...

Aim Temporal dynamics of biodiversity along tropical elevational gradients are unknown. We studied seasonal changes of Lepidoptera biodiversity along the only complete forest elevational gradient in the Afrotropics. We focused on shifts of species richness patterns, seasonal turnover of communities and seasonal shifts of species’ elevational ranges...