Christian Zang

Christian Zang
Hochschule Weihenstephan-Triesdorf · Department of Forestry

Professor

About

65
Publications
34,205
Reads
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3,594
Citations
Introduction
Hello, I'm Christian. I am a Professor for Forests and Climate Change the University of Applied Sciences Weihenstephan-Triesdorf and a TUM Junior Fellow at the Professorship for Land Surface-Atmosphere Interactions at the Technische Universität München, leading the HyBBEx project (hybbex.org). My main research interests are ecoystem responses to climate and climatic extremes with a focus on tree-growth. I have a website at czang.org.
Additional affiliations
September 2018 - present
Technical University of Munich
Position
  • Group Leader
Description
  • Junior Research Group Leader and TUM Junior Fellow in the context of the Bavarian Climate Research Network
January 2016 - August 2018
Technical University of Munich
Position
  • Assistant
Description
  • Assistant at the Professorship for Land Surface-Atmosphere Interactions
October 2014 - October 2015
University of Stirling
Position
  • Associated scientist
Description
  • Visiting member of staff

Publications

Publications (65)
Article
Full-text available
The future performance of native tree species under climate change conditions is frequently discussed, since increasingly severe and more frequent drought events are expected to become a major risk for forest ecosystems. To improve our understanding of the drought tolerance of the three common European temperate forest tree species Norway spruce, s...
Article
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The R package treeclim helps perform numerical calibration of proxy-climate relationships, with an emphasis on tree-ring chronologies. The package provides a unified, fast, and public-domain compilation of established methods while adding novel functionality not implemented in other software. treeclim includes static and moving bootstrapped respons...
Article
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It has been argued in the literature that global temperature increased at a reduced rate between approximately 1998 and 2013, a phenomenon known as the ‘global warming hiatus’. Statistically motivated studies searching for numerical evidence for this episode typically argue against the detectability of a slowdown. At the same time, process-oriented...
Article
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Damage by late spring frost is a risk deciduous trees have to cope with in order to optimize the length of their growing season. The timing of spring phenological development plays a crucial role, not only at the species level, but also at the population and individual level, since fresh new leaves are especially vulnerable. For the pronounced late...
Article
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Climatically controlled allocation to reproduction is a key mechanism by which climate influences tree growth and may explain lagged correlations between climate and growth. We used continent-wide datasets of tree-ring chronologies and annual reproductive effort in Fagus sylvatica from 1901-2015 to characterise relationships between climate, reprod...
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Over the last decades, the Amazon rainforest has been hit by multiple severe drought events. Here, we assess the severity and spatial extent of the extreme drought years 2005, 2010 and 2015/16 in the Amazon region and their impacts on the regional carbon cycle. As an indicator of drought stress in the Amazon rainforest, we use the widely applied ma...
Article
Tree-ring chronologies encode interannual variability in forest growth rates over long time periods from decades to centuries or even millennia. However, each chronology is a highly localized measurement describing conditions at specific sites where wood samples have been collected. The question whether these local growth variabilites are represent...
Article
Detecting pointer years in tree-ring data is a central aspect of dendroecology. Pointer years are usually represented by extraordinary secondary tree growth, which is often interpreted as a response to abnormal environmental conditions such as late-frosts or droughts. Objectively identifying pointer years in larger tree-ring networks and relating t...
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The mechanistic pathways connecting ocean-atmosphere variability and terrestrial productivity are well-established theoretically, but remain challenging to quantify empirically. Such quantification will greatly improve the assessment and prediction of changes in terrestrial carbon sequestration in response to dynamically induced climatic extremes....
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The growth of past, present, and future forests was, is and will be affected by climate variability. This multifaceted relationship has been assessed in several regional studies, but spatially resolved, large-scale analyses are largely missing so far. Here we estimate recent changes in growth of 5800 beech trees ( Fagus sylvatica L.) from 324 sites...
Article
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Forest decline, in course of climate change, has become a frequently observed phenomenon. Much of the observed decline has been associated with an increasing frequency of climate change induced hotter droughts while decline induced by flooding, late-frost, and storms also play an important role. As a consequence, tree mortality rates have increased...
Article
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Pulses of tree mortality caused by drought have been reported recently in forests around the globe, but large-scale quantitative evidence is lacking for Europe. Analyzing high-resolution annual satellite-based canopy mortality maps from 1987 to 2016 we here show that excess forest mortality (i.e., canopy mortality exceeding the long-term mortality...
Preprint
Full-text available
Over the last decades, the Amazon rainforest was hit by multiple severe drought events. Here we assess the severity and spatial extent of the extreme drought years 2005, 2010, and 2015/2016 in the Amazon region and their impacts on the carbon cycle. As an indicator of drought stress in the Amazon rainforest, we use the widely applied maximum cumula...
Article
The expected increase in drought severity and frequency as a result of anthropogenic climate change leads to concerns about the ability of native tree species to cope with these changes. To determine the susceptibility of Fagus sylvatica (European beech) and Quercus robur (pedunculate oak) – the two dominant deciduous tree species in Central Europe...
Article
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The European heatwave of 2018 led to record-breaking temperatures and extremely dry conditions in many parts of the continent, resulting in widespread decrease in agricultural yield, early tree-leaf senescence, and increase in forest fires in Northern Europe. Our study aims to capture the impact of the 2018 European heatwave on the terrestrial ecos...
Preprint
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The European heatwave of 2018 led to record-breaking temperatures and extremely dry conditions in many parts of the continent resulting in widespread decrease in agricultural yield, early tree-leaf senescence, and increase in forest fires in Northern Europe. Our study aims to capture the impact of the 2018 European heatwave on terrestrial ecosystem...
Article
In the context of extreme event ecology, identification of pointer years has become a central aspect of tree-ring research. However, the variety of methods employed for pointer year detection since the introduction of the concept in 1979 impedes a direct comparison among studies. Moreover, most commonly used methods partly rely on arbitrarily selec...
Article
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Amazonian ecosystems are major biodiversity hotspots and carbon sinks that may lose species to extinction and become carbon sources due to extreme dry or warm conditions. We investigated the seasonal patterns of high-resolution solar-induced chlorophyll fluorescence (SIF) measured by the satellite Orbiting Carbon Observatory-2 (OCO-2) across the Am...
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Vegetation responds to drought through a complex interplay of plant hydraulic mechanisms, posing challenges for model development and parameterization. We present a mathematical model that describes the dynamics of leaf water-potential over time while considering different strategies by which plant species regulate their water-potentials. The model...
Article
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In 2018, Central Europe experienced one of the most severe and long-lasting summer drought and heat wave ever recorded. Before 2018, the 2003 millennial drought was often invoked as the example of a “hotter drought”, and was classified as the most severe event in Europe for the last 500 years. First insights now confirm that the 2018 drought event...
Article
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In recent decades, an increasing persistence of atmospheric circulation patterns has been observed. In the course of the associated long-lasting anticyclonic summer circulations, heatwaves and drought spells often coincide, leading to so-called hotter droughts. Previous hotter droughts caused a decrease in agricultural yields and an increase in tre...
Preprint
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In their response to critical comments on their study, Bastin et al. (2019) claim that their numbers are correct and provide an updated description of the carbon uptake calculation. However, it remains unclear whether the authors describe the original calculation or a completely new one. In addition, the authors calculate their best estimate (205 G...
Preprint
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We believe the carbon removal potential of 205 Gt C reported by Bastin et al. (2019) to be overestimated. The authors did not consider the carbon already stored on the land with identified tree restoration potential. For instance, grasslands and degraded forests have similar soil carbon stocks as old-growth forests. Accounting for these inconsisten...
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A reconstruction of hydroclimate with an annual resolution covering millennia for a geographically limited region in continental Europe significantly improves our knowledge of past climate dynamics. With the use of an extensive collection of oak ring-width series (Quercus robur and Quercus petraea) from living trees, historic timbers and subfossil...
Article
Defining and quantifying drought is essential when studying ecosystem responses to such events. Yet, many studies lack either a clear definition of drought, and/or erroneously assume drought under conditions within the range of “normal climatic variability” (c.f. Slette et al., 2019). To improve the general characterization of drought conditions in...
Article
Full-text available
In recent decades, an increasing persistence of atmospheric circulation patterns has been observed. In the course of the associated long-lasting anticyclonic summer circulations, heat waves and drought spells often coincide, leading to so-called hotter droughts. Previous hotter droughts caused a decrease in agricultural yields and increase in tree...
Preprint
Full-text available
In recent decades, an increasing persistence of atmospheric circulation patterns has been observed. In the course of the associated long-lasting anticyclonic summer circulations, heat waves and drought spells often coincide, leading to so-called hotter droughts. Previous hotter droughts caused a decrease in agricultural yields and increase in tree...
Article
Aiming for refined drought characterization, the validation of targeted drought indices is of vital importance. In this study, we compared the performance of established drought indices-the SPI (Standardized Precipitation Index) and the SPEI (Standardized Precipitation Evapotranspiration Index)-with standardized drought indices using a recently dev...
Article
Full-text available
Comparing model output and observed data is an important step for assessing model performance and quality of simulation results. However, such comparisons are often hampered by differences in spatial scales between local point observations and large-scale simulations of grid cells or pixels. In this study, we propose a generic approach for a pixel-...
Article
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A reconstruction of hydroclimate with an annual or sub-annual resolution covering the entire Holocene for a geographically limited region would significantly improve our knowledge of past climate dynamics, but has not been developed so far. With the use of an extensive collection of oak total ring-width series (Quercus robur and Quercus petraea) fr...
Article
Full-text available
Comparing model output and observed data is an important step for assessing model performance and quality of simulation results. However, such comparisons are often hampered by differences in spatial scales between local point observations and large-scale simulations of grid-cells or pixels. In this study, we propose a generic approach for a pixel-...
Article
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Ch., Sutcliffe L., Leuschner Ch., 2017. Assessing future suitability of tree species under climate change by multiple methods: a case study in southern Germany. Ann. For. Res. 60(1): _-_. Abstract. We compared results derived using three different approaches to assess the suitability of common tree species on the Franconian Plateau in southern Germ...
Article
Overlaid to a general reduction of European beech and sessile oak tree growth over the recent decades in the Mediterranean Basin, tree-ring records from western Mediterranean populations display a stronger growth decrease than eastern populations. We investigate here to what extent the impact of sustained atmospheric circulation patterns in summert...
Article
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In the first section of this study, we explored the relationship between ring width index (RWI) and normalized difference vegetation index (NDVI) time series on varying timescales and spatial resolutions, hypothesizing positive associations between RWI and current and previous- year NDVI at 69 forest sites scattered in the Northern Hemisphere. We n...
Article
Increasing frequency and intensity of drought extremes associated with global change are a key challenge for forest ecosystems. Consequently, the quantification of drought effects on tree growth as a measure of vitality is of highest concern from the perspectives of both science and management. To date, a multitude of drought indices have been used...
Article
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Tree masting is one of the most intensively studied ecological processes. It affects nutrient fluxes of trees, regeneration dynamics in forests, animal population densities, and ultimately influences ecosystem services. Despite a large volume of research focused on masting, its evolutionary ecology, spatial and temporal variability and environmenta...
Article
In dendroclimatology, testing the stability of transfer functions using cross-calibration verification (CCV) statistics is a common procedure. However, the frequently used statistics reduction of error (RE) and coefficient of efficiency (CE) merely assess the skill of reconstruction for the validation period, which does not necessarily reflect poss...
Article
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Alpine ecosystems face multiple environmental impacts caused by extraordinary rapid warming. One of the impacts caused by rising temperature is the prolongation of the growing season. To determine temperature-driven variation in leaf and xylem phenology, we studied Norway spruce and European beech along two elevational transects in the Northern Lim...
Article
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In the face of climate warming, maps of potential tree species distribution can support forest management planning at coarse scales. For evaluating future suitability, conditions at the rear edge, i.e. at the meridional and lower altitudinal limits of species distribution, are of particular importance. Therefore, we present the concept of climatic...
Article
The International Tree-Ring Data Bank (ITRDB) is the main public archive of digital tree-ring parameters. Due to its comprehensive spatio-temporal coverage, its ring-width data is acknowledged in many studies where high-resolution proxies of climate or tree-growth are needed on large scales. A main drawback of existing approaches to browsing the IT...
Article
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Bark beetle outbreaks are a major threat to forest productivity, and a robust forecast of early flight activity is necessary for inhibition or mitigation of large-scale infestations. We used spring phenology of common wild plants in a phenology-based forecasting approach for European spruce bark beetle Ips typographicus L. early flight activity in...
Article
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Climate model projections suggest widespread drying in the Mediterranean Basin and wetting in Fennoscandia in the coming decades largely as a consequence of greenhouse gas forcing of climate. To place these and other “Old World” climate projections into historical perspective based on more complete estimates of natural hydroclimatic variability, we...
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Tree-ring stable isotopes, providing insight into drought-induced eco-physiological mechanisms, are frequently used to reconstruct past changes in growing season temperature and precipitation. Their climatic response is, however, still not fully understood, particularly for data originating from non-extreme, mid-latitude environments with differing...
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Mountain forests offer a range of socio-economic and ecological services, e.g. providing wood harvest products, serving as hotspots of biodiversity and fulfilling protective functions. In the European Alps, where these environments are dominated by drought-sensitive Norway spruce, it has been questioned whether these services can be secured in the...
Article
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Key message Growth response to climate differs between species and elevation. Fir is the most drought-tolerant species. The mountain forests are robust to the climatic changes until now. Abstract Alpine mountain forests provide a wide range of ecological and socio-economic services. Climate change is predicted to challenge these forests, but there...
Article
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Quantifying the interannual variability (IAV) of the terrestrial ecosystem productivity and its sensitivity to climate is crucial for improving carbon budget predictions. In this context it is necessary to disentangle the influence of climate from impacts of other mechanisms underlying the spatiotemporal patterns of IAV of the ecosystem productivit...
Article
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Quantifying the interannual variability (IAV) of the terrestrial productivity and its sensitivity to climate is crucial for improving carbon budget predictions. However, the influence of climate and other mechanisms underlying the spatiotemporal patterns of IAV of productivity are not well understood. In this study we investigated the spatiotempora...
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• Context The rising demand of energy wood for heating purposes in Germany leads to concerns regarding the overexploitation of forests. A major aspect is the impact of whole-tree harvesting on long-term productivity of forest soils. • Aims This study aimed to analyze the effects of nutrient removal on productivity using the historically prevalent p...