Constantin M. Zohner

ETH Zurich | ETH Zürich · Institute of Integrative Biology Zurich

Plant phenology is crucial for understanding plant growth and climate feedback. It affects canopy structure, surface albedo, and carbon and water fluxes. While the influence of environmental factors on phenology is well‐documented, the role of plant intrinsic factors, particularly internal physiological processes and their interaction with external...

Widespread autumn cooling occurred in the northern hemisphere (NH) during the period 2004–2018, primarily due to the strengthening of the Pacific Decadal Oscillation and Siberian High. Yet, while there has been considerable focus on the warming impacts, the effects of natural cooling on autumn leaf senescence and plant productivity have been largel...

Balancing forest conservation and agricultural production is essential for a sustainable future. Here we review the scientific evidence for the relationships between forests and agricultural productivity across different scales, summarizing the contexts under which trees limit, maintain, or enhance agricultural productivity. While synergies and tra...

Global warming poses an unprecedented threat to agroecosystems. Although temperature increases are more pronounced during winter than in other seasons, the impact of winter warming on crop biomass carbon has not been elucidated. Here we integrate global observational data with a decade-long field experiment to uncover a significant negative correla...

More intense fire weather due to climate change is implicated as a key driver of recent extreme wildfire events. As fuel stocks, the roles of vegetation and its phenology change in wildfire dynamics, however, are not fully appreciated. Using long-term satellite-based burned areas and photosynthesis observations, we reveal that an earlier peak photo...

Aims Effect of nitrogen deposition on soil organic carbon and the underlying mechanisms in grassland ecosystems remains a topic of debate. Moreover, previous research has primarily concentrated on interaction between carbon and nitrogen cycles in response to nitrogen deposition, with less attention paid to how nitrogen-induced phosphorus deficits m...

Understanding the sensitivity of spring leaf-out dates to temperature (ST) is integral to predicting phenological responses to climate warming and the consequences for global biogeochemical cycles. While variation in ST has been shown to be influenced by local climate adaptations, the impact of biodiversity remains unknown. Here we combine 393,139...

Permafrost regions contain approximately half of the carbon stored in land ecosystemsand have warmed at least twice as much as any other biome. This warming has influencedvegetation activity, leading to changes in plant composition, physiology, and biomassstorage in aboveground and belowground components, ultimately impacting ecosys-tem carbon bala...

The emergence of alternative stable states in forest systems has significant implications for the functioning and structure of the terrestrial biosphere, yet empirical evidence remains scarce. Here, we combine global forest biodiversity observations and simulations to test for alternative stable states in the presence of evergreen and deciduous for...

While research on terrestrial silicon (Si) biogeochemistry and its beneficial effects for plants has received significant attention in last decades, the reasons for the emergence of high-Si taxa remain unclear. Although the “arms race” hypothesis (i.e. increased silicification through co-evolution with mammalian grazers) has received some support,...

Urban vegetation is essential for the quality of life in cities. Despite direct vegetation loss during urban expansion, urbanization can indirectly enhance vegetation greening through various factors. Yet, it remains unclear what conditions promoted these greening trends within cities. We quantified the greenness trends in 294 Chinese cities based...

Precipitation is an important factor influencing the date of leaf senescence (DFS), which in turn affects carbon uptake of terrestrial ecosystems. However, the temporal patterns of precipitation frequency (P freq ) and its impact on DFS remain largely unknown. Using both long-term carbon flux data and satellite observation of DFS across the Norther...

The initiation of spring leaf-out is a critical determinant of the growing season in trees, affecting primary production and species interactions in forest ecosystems. Variations in the timing of leaf-out among tree species are linked to their differential progression of bud dormancy. However, identifying reliable markers for bud dormancy has been...

Climate change is causing widespread land surface greening in spring1–4, but the impacts of anthropogenic air pollution on these changes remain poorly understood. Using global ground and satellite observations of fine particulate matter ≤ 2.5 μm (PM2.5) from 2000 to 2020, here we show that PM2.5 concentration offsets global spring greening as indic...

More intense fire weather due to climate change is implicated as a key driver of recent increases in regional wildfire activity. As fuel stocks, the roles of vegetation itself and its phenology change in wildfire dynamics, however, are not fully appreciated. Using long-term satellite-based burned areas and photosynthesis observations, we reveal tha...

Forests are a substantial terrestrial carbon sink, but anthropogenic changes in land use and climate have considerably reduced the scale of this system¹. Remote-sensing estimates to quantify carbon losses from global forests2–5 are characterized by considerable uncertainty and we lack a comprehensive ground-sourced evaluation to benchmark these est...

The strong control of temperature on the timing of plant phenology is expected to cause substantial shifts in flowering times under climate change. Yet, the sensitivity of flowering phenology in dryland regions to climate change, and the potential implications for community composition, remain largely unexplored. Here, we investigate the effects of...

Understanding what controls global leaf type variation in trees is crucial for comprehending their role in terrestrial ecosystems, including carbon, water and nutrient dynamics. Yet our understanding of the factors influencing forest leaf types remains incomplete, leaving us uncertain about the global proportions of needle-leaved, broadleaved, ever...

Forests cool the land surface in warm regions and warm the land surface in cool regions. Because these local temperature buffering effects depend on background climate, increasingly large areas might experience forest cooling effects as the climate warms. Here, using statistical modeling, we quantified changes in the sensitivity of land surface tem...

Understanding the sensitivity of spring leaf-out dates to temperature (S T ) is integral to predicting phenological responses to climate warming and the consequences for global biogeochemical cycles. While variation in S T has been shown to be influenced by local climate adaptations, the impact of biodiversity on phenological sensitivity remains un...

Global warming is advancing the timing of spring leaf‐out in temperate and boreal plants, affecting biological interactions and global biogeochemical cycles. However, spatial variation in spring phenological responsiveness to climate change within species remains poorly understood. Here, we investigated variation in the responsiveness of spring phe...

Quantifying biodiversity across the globe is critical for transparent reporting and assessment under the Kunming-Montreal Global Biodiversity Framework. Understanding the full complexity of biodiversity requires consideration of the variation of life across genetic, species and ecosystem levels. Achieving this in a globally-standardized way remains...

Determining the drivers of non-native plant invasions is critical for managing native ecosystems and limiting the spread of invasive species1,2. Tree invasions in particular have been relatively overlooked, even though they have the potential to transform ecosystems and economies3,4. Here, leveraging global tree databases5-7, we explore how the phy...

The frequency and intensity of wildfires in recent decades have reached unprecedented levels ¹⁻³ , raising questions about the role of vegetation phenology in driving these changes. By examining both terrestrial fire perimeters and satellite observations, we found that an earlier peak photosynthesis timing (PPT) contributes to the acceleration of w...

Climate change is shifting the growing seasons of plants, affecting species performance and biogeochemical cycles. Yet how the timing of autumn leaf senescence in Northern Hemisphere forests will change remains uncertain. Using satellite, ground, carbon flux, and experimental data, we show that early-season and late-season warming have opposite eff...

To quantify the ecological consequences of recent nationwide restoration efforts in China, spatially explicit information on forest biomass carbon stock changes over the past 20 years is critical. However, long-term biomass tracking at the national scale remains challenging as it requires continuous and high-resolution monitoring. Here, we characte...

Leaf phenology is key for regulating total growing-season mass and energy fluxes. Long-term temporal trends towards earlier leaf unfolding are observed across Northern Hemisphere forests. Phenological dates also vary between years, whereby end-of-season (EOS) dates correlate positively with start-of-season (SOS) dates and negatively with growing-se...

Over the past decades, global warming has led to a lengthening of the time window during which temperatures remain favorable for carbon assimilation and tree growth, resulting in a lengthening of the green season. The extent to which forest green seasons have tracked the lengthening of this favorable period under climate warming, however, has not b...

To quantify the ecological consequences of recent nation wide restoration efforts in China, spatially explicit information on woody biomass changes over the 21st century is critical However, long term biomass tracking at the national scale remains challenging as it requires continuous and high resolution monitoring . Here, we mapped above and below...

The degree to which elevated CO2 concentrations (e[CO2]) increase the amount of carbon (C) assimilated by vegetation plays a key role in climate change. However, due to the short‐term nature of CO2 enrichment experiments and the lack of reconciliation between different ecological scales, the effect of e[CO2] on plant biomass stocks remains a major...

Rapid technological advancements and increasing data availability have improved the capacity to monitor and evaluate Earth's ecology via remote sensing. However, remote sensing is notoriously ‘blind’ to fine‐scale ecological processes such as interactions among plants, which encompass a central topic in ecology. Here, we discuss how remote sensing...

Urban environments, regarded as “harbingers” of future global change, may exert positive or negative impacts on urban vegetation growth. Because of limited ground-based experiments, the responses of vegetation to urbanization and its associated controlling factors at the global scale remain poorly understood. Here, we use satellite observations fro...

Due to massive energetic investments in woody support structures, trees are subject to unique physiological, mechanical, and ecological pressures not experienced by herbaceous plants. Despite a wealth of studies exploring trait relationships across the entire plant kingdom, the dominant traits underpinning these unique aspects of tree form and func...

The growing-season length of temperate and boreal trees has a strong effect on the global carbon cycle. Yet, a poor understanding of the drivers of phenological processes, such as autumn leaf senescence in deciduous trees, limits our capacity to estimate growing-season lengths under climate change. While temperature has been shown to be an importan...

Understanding how leaf autumn phenology varies at different spatio-temporal scales is key to accurately predicting phenological changes under future climate. Recent projections and observations of autumn phenology in deciduous temperate and boreal forests appear conflicting. At the interannual scale, autumn senescence correlates positively with spr...

Climate warming-induced shifts in spring phenology have substantially affected the structure and function of terrestrial ecosystems and global biogeochemical cycles. Spring phenology is primarily triggered by spring temperature and is also affected by daylength and winter chilling, yet the relative importance of these cues across spatial gradients...

Climate change is causing shifts in the growing seasons of plants1,2, affecting species performance and interactions3,4 as well as global carbon, water and nutrient cycles5,6. How the timing of autumn leaf senescence in extra-tropical forests will change remains unclear because of the complex seasonal interaction of climate warming, earlier and enh...

Trees growing at a particular latitude in Eastern North America (ENA) receive more autumn solar irradiation than do trees growing at the same latitude in Europe, a difference that could partly explain the higher percentage of anthocyanin-producing deciduous species in ENA compared with European floras. A proposed link between autumn light intensity...

Leaf phenology is key for regulating total growing season mass and energy fluxes. Long-term temporal trends towards earlier leaf unfolding are observed across Northern Hemisphere forests. Phenological dates also vary between years, whereby end-of-season (EOS) dates correlate positively with start-of-season (SOS) dates and negatively with growing se...

A bstract Due to massive energetic investments in woody support structures, trees are subject to unique physiological, mechanical, and ecological pressures not experienced by herbaceous plants. When considering trait relationships across the entire plant kingdom, plant trait frameworks typically must omit traits unique to large woody species, there...

Aim Ongoing climate warming has been widely reported to delay autumn phenology, which in turn impacts carbon, water, energy and nutrient balances at regional and global scales. However, the underlying mechanisms of autumn phenology responses to climate change have not been fully elucidated. The aims of this study were to determine whether brighteni...

Microclimatic effects (light, temperature) are often neglected in phenological studies and little information is known about the impact of resource availability (nutrient and water) on tree’s phenological cycles. Here we experimentally studied spring and autumn phenology in four temperate trees in response to changes in bud albedo (white‐painted vs...

A poor understanding of the fraction of global plant biomass occurring belowground as roots limits our understanding of present and future ecosystem function and carbon pools. Here we create a database of root-mass fractions (RMFs), an index of plant below- versus aboveground biomass distributions, and generate quantitative, spatially explicit glob...

Earlier leaf‐out and later autumn leaf senescence under climate warming have been linked to increases in plant productivity and ecosystem carbon uptake. Yet, despite the potential implications of shifting phenology for plant carbon uptake, the degree to which phenological changes affect overall plant growth and the partitioning between above‐ and b...

Premise: State-sponsored weather stations became ubiquitous by the 1880s, yet many old climate data and phenological observations still need to be digitized and made accessible. Methods: We here make available flowering times for 450 species of herbs and shrubs gathered in 1844 by Carl Friedrich Philipp von Martius (1794-1868), director of the M...

Over the last decades, spring leaf‐out of temperate and boreal trees has substantially advanced in response to global warming, affecting terrestrial biogeochemical fluxes and the Earth's climate system. However, it remains unclear whether leaf‐out will continue to advance with further warming because species’ effective chilling temperatures, as wel...

Our study showed that increases in seasonal productivity drive earlier autumn senescence of temperate trees. Norby argues that this finding is contradicted by observations from free-air CO 2 enrichment (FACE) experiments, where elevated CO 2 has been found to delay senescence in some cases. We provide a detailed answer showing that the results from...

Limits to the growing season The length of the growing season in temperate forests has been increasing under recent climate change because of earlier leaf emergence and later leaf senescence. However, Zani et al. show that this trend might be reversed as increasing photosynthetic productivity begins to drive earlier autumn leaf senescence (see the...

Late-spring frosts (LSFs) affect the performance of plants and animals across the world's temperate and boreal zones, but despite their ecological and economic impact on agriculture and forestry, the geographic distribution and evolutionary impact of these frost events are poorly understood. Here, we analyze LSFs between 1959 and 2017 and the resis...

Late-spring frosts (LSFs) affect the performance of plants and animals across the world’s temperate and boreal zones, but despite their ecological and economic impact on agriculture and forestry, the geographic distribution and evolutionary impact of these frost events are poorly understood. Here, we analyze LSFs between 1959 and 2017 and the resis...

Late-spring frosts (LSFs) affect the performance of plants and animals across the world’s temperate and boreal zones, but despite their ecological and economic impact on agriculture and forestry, the geographic distribution and evolutionary impact of these frost events are poorly understood. Here, we analyze LSFs between 1959 and 2017 and the resis...

Climate warming is currently advancing spring leaf‐out of temperate and boreal trees, enhancing net primary productivity (NPP) of forests. However, it remains unclear whether this trend will continue, preventing for accurate projections of ecosystem functioning and climate feedbacks. Several ecophysiological mechanisms have been proposed to regulat...

Aim Trees need to avoid frost damage to their young leaves by leafing out after the occurrence of the last frost, yet they also need to start photosynthesis early in the season to achieve sufficient growth. This trade‐off leads to the hypothesis that ‘safety margins’ against spring frost should become shorter, the longer the winter duration, perhap...

Our study quantified the global tree restoration potential and its associated carbon storage potential under existing climate conditions. Skidmore et al . dispute our findings, using as reference a yearly estimation of carbon storage that could be reached by 2050. We provide a detailed answer highlighting misunderstandings in their interpretation,...

Temperature differences between cities and the countryside have been regarded as useful surrogates for ecological responses to climate warming. However, research reveals mismatch between the phenological responses to spatial and temporal temperature gradients as well as complex interactions between urbanization and climate.

Premise The proportion of woody dicots with toothed leaves increases toward colder regions, a relationship used to reconstruct past mean annual temperatures. Recent hypotheses explaining this relationship are that (1) leaves in colder regions are thinner, requiring thick veins for support and water supply, with the resulting craspedodromous venatio...

Our study quantified the global tree restoration potential and its associated carbon storage potential under existing climate conditions. We received multiple technical comments, both supporting and disputing our findings. We recognize that several issues raised in these comments are worthy of discussion. We therefore provide a detailed common answ...

[This corrects the article DOI: 10.1371/journal.pone.0217592.].

The timing of spring leaf emergence in temperate regions directly influences global biogeochemical cycles and species interactions (Richardson et al. 2013). Understanding the environmental drivers of leaf‐out is thus essential to forecasting ecosystem responses to global climate change. These drivers have long been thought to be species‐specific co...

Combating climate change requires unified action across all sectors of society. However, this collective action is precluded by the ‘consensus gap’ between scientific knowledge and public opinion. Here, we test the extent to which the iconic cities around the world are likely to shift in response to climate change. By analyzing city pairs for 520 m...

The potential for global forest cover The restoration of forested land at a global scale could help capture atmospheric carbon and mitigate climate change. Bastin et al. used direct measurements of forest cover to generate a model of forest restoration potential across the globe (see the Perspective by Chazdon and Brancalion). Their spatially expli...