Norbert Kunert

• apl. Prof. Dr.
• akademischer Oberrat at University of Bayreuth

Leaf turgor loss point has been recognized as an important plant physiological trait explaining a species’ drought tolerance (πtlp). Less is known about the variation of πtlp in time and how seasonal or interannual differences in water availability are affecting πtlp as a static trait. I monitored the seasonal variation of πtlp during a drought yea...

Die Wälder in Deutschland haben mit den Folgen des Klimawandels stark zu kämpfen. Eine Möglichkeit, die Anpassung von Wirtschaftswäldern an die sich verändernden klimatischen Gegebenheiten voranzutreiben, ist der vermehrte Anbau von Baumarten aus südlicheren Breiten. Wie gut diese Arten mit unserem Herbstklima zurechtkommen, wurde wenig untersucht....

As climate change thrives, and the frequency of intense droughts is affecting many forested regions, a mechanistic understanding of the factors conferring drought tolerance in trees is increasingly important. However, studies linking the observed growth reduction to mechanistic traits are still rare. We compared the median growth anomalies of 16 na...

The summer of 2022 has been the so far hottest summer on record in Central Europe. High temperatures negatively affect the physiology of plants and cause considerable thermal stress in particular on the leaf level. The assessment of the temperature-dependent decline of the quantum use efficiency of the photosystem II (Fv/Fm) has gained much popular...

Tropical forests are important carbon sinks as they store huge amounts of carbon and are thus essential players within the global carbon cycle. While good estimates of the gross and net primary productivity (GPP and NPP, respectively) of tropical forests exist, we still lack a cohesive study on the contribution of different tree sizes to the overal...

Hydraulic testing of isolated sapwood from mature tree trunks is time-consuming and prone to errors, whereas the measurement of compression strength is a standardized and rapid wood technological application. In this study, we aimed to analyze if compression stress perpendicular to the grain relates to hydraulic vulnerability of mature Norway spruc...

Durch die vermehrte Trockenheit und Hitze in den letzten Jahren wurde deutlich, mit welcher Dringlichkeit der Kulturforst an die sich ändernden klimatischen Bedingungen angepasst werden muss. Welche Baumarten zukunftsfähig sein könnten, wird momentan intensiv diskutiert. Empfehlungen zu Praxisanbauversuchen alternativer Baumarten beruhen zumeist au...

Climate change is causing more frequent and severe climatic events, such as extreme heat and co-occurring drought, potentially accelerating tree mortality. Which tree species will cope better with those extreme events is still being researched. This study focuses on heat as a physiological stress factor and interspecific variation of thermal tolera...

Considering the global intensification of aridity in tropical biomes due to climate change, we need to understand what shapes the distribution of drought sensitivity in tropical plants. We conducted a pantropical data synthesis representing 1117 species to test whether xylem‐specific hydraulic conductivity (KS), water potential at leaf turgor loss...

Über Jahrhunderte waren die Niederwald- und die Mittelwaldwirtschaft wichtige forstliche Betriebsarten. Flächen, welche mit solch traditionellen Formen der Waldwirtschaft bewirtschaftet werden, gelten heute aufgrund der hohen Biodiversität als Ökosysteme von besonders hohem Naturschutzwert. Aber auch unter dem Aspekt des Klimawandels bieten diese t...

With climate warming, the frequency and severity of extreme climatic events such as heat waves increase the risk of temperature-induced leaf damage. Severe damage can significantly weaken forest trees and lead to accelerated forest mortality. Cross-species studies investigating the thermal sensitivity of temperate tree species are still rare. Here,...

Drought events are increasing with climate change and threaten the future of industrial plantations in Southeast Asia. Drought tolerance has been well investigated for oil palm plantations. A comparative study on the tolerance of different woody crop species is still missing. We assessed the leaf turgor loss point of five common woody crop species...

Mixed species forests are known to have a higher gross primary productivity (GPP) and net primary productivity (NPP) than forests containing only one single tree species. Trees growing in mixtures are characterized by higher autotrophic respiration (Ra), this results in a lower carbon use efficiency of mixed species forests compared to monocultures...

International online meeting on ‘Plant Pneumatics’, Ulm University and the University of Natural Resources and Life Sciences (BOKU), Ulm (Germany) and Vienna (Austria), 22 April and 29 September 2021

Die zunehmende Anzahl an Extremwettereignissen beeinflusst auch unsere Wälder. Um die Waldökosysteme zu erhalten, stehen die Waldbesitzer vor der großen Aufgabe, die Waldbestände an die sich ändernden Umweltbedingungen anzupassen. Hierbei liegt der Fokus vor allem auf der Anpassung der Waldbestände an Trockenheit und Dürreperioden. Hitzewellen und...

• Climate change-related environmental stress has been recognized as a driving force in accelerating forest mortality over the last decades in Central Europe. Here, we aim to elucidate the thermal sensitivity of three native conifer species, namely Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and silver fir (Abies alba), and three non...

Deep‐water access is arguably the most effective, but under‐studied, mechanism that plants employ to survive during drought. Vulnerability to embolism and hydraulic safety margins can predict mortality risk at given levels of dehydration, but deep‐water access may delay plant dehydration. Here, we tested the role of deep‐water access in enabling su...

The effects of climate change on tropical forests will depend on how diverse tropical tree species respond to drought. Current distributions of evergreen and deciduous tree species across local and regional moisture gradients reflect their ability to tolerate drought stress, and might be explained by functional traits. We measured leaf water potent...

Carbon (C) fixation, allocation, and metabolism by trees set the basis for energy and material flows in forest ecosystems and define their interactions with Earth’s changing climate. However, while many studies have considered variation in productivity with latitude and climate, we lack a cohesive synthesis on how forest carbon fluxes vary globally...

As climate change drives increased drought in many forested regions, mechanistic understanding of the factors conferring drought tolerance in trees is increasingly important. The dendrochronological record provides a window through which we can understand how tree size and traits shape growth responses to droughts. We analyzed tree‐ring records for...

The last years, Central European forests have suffered from drought as a direct consequence of climate change. All these forests have a long management history and it lies in the landowner’s responsibility to replant damaged forests. Hence, landowners and the government are searching currently for species suitable to replant in areas affected by tr...

Das Absterben von Bäumen wird normalerweise nicht nur durch ein Ereignis, sondern durch eine Reihe von ungünstigen Ereignissen hervorgerufen. Meist ist dann für das letztendliche Absterben ein leicht zu erkennender Sekundärschädling verantwortlich, der eigentliche auslösende Stressor bleibt meist unbekannt. Neueste pflanzenphysiologische Untersuchu...

Accelerating and massive tree mortality in the two conifer species Norway spruce and Scots pine is currently observed in Central Europe. Consecutive dry years are made responsible for this phenomenon. Leaf trait measurements, in specific leaf osmotic potential (πosm) and leaf water potential at turgor loss (πtlp), indicate that the underlying mecha...

Leaf traits have been shown to explain a great fraction of differences in growth rates in trees. With this study, we evaluate if differences in growth performance of different species mixtures in a tropical tree plantation can be attributed to the plasticity of the specific leaf area index. We compare the specific leaf area of five native Panamania...

Verminderte Niederschläge und gehäuft auftretende Trockenheit machen den Wäldern zunehmend zu schaffen. Eichen gelten als gut angepasst an trockene Standorte und daher als besonders zukunftsfähig unter den sich ändernden Klimaverhältnissen, jedoch ist die Trockentoleranz von Baumarten oft schwer zu quantifi zieren. Hier wird das Blattwasserpotenzia...

Tree autotrophic respiratory processes, especially stem respiration or stem CO2 efflux (Estem), are important components of the forest carbon budget. Despite the efforts to investigate the controlling processes of Estem in the last years a considerable lack in our knowledge remains on the abiotic and biotic drivers affecting Estem dynamics. It has...

Zusätzlich zum Diplodia -Triebsterben an Waldkiefern (Pinus sylvestris) tritt in Mittelfranken immer häufiger de latente Holzfäuleerreger Krause Glucke oder Fette Henne (Sparassis crispa, Sparassidaceae) auf. Die starke Zunahme dieser Sekundärschädlinge lässt ein durch den Klimawandel hervorgerufenes flächiges Kiefernsterben erwarten.

The ratio of CO2 efflux to O2 influx (ARQ, apparent respiratory quotient) in tree stems is expected to be 1.0 for carbohydrates, the main substrate supporting stem respiration. In previous studies of stem fluxes, ARQ values below 1.0 were observed and hypothesized to indicate retention of respired carbon within the stem. Here, we demonstrate that s...

Hydrological processes in forest stands are mainly influenced by the tree species composition and their morpho-physiological characteristics. Few studies on anatomical patterns that govern plant hydraulics were conducted in tropical forest ecosystems. Thus, we used dye immersion to analyze sapwood area patterns of 34 trees belonging to 26 species f...

Nonstructural carbon (NSC) reserves act as buffers to sustain tree activity during periods when carbon (C) assimilation does not meet C demand, but little is known about their age and accessibility; we designed a controlled girdling experiment in the Amazon to study tree survival on NSC reserves. We used bomb‐radiocarbon (¹⁴C) to monitor the time e...

Der Klimawandel stellt für den Waldbauern eine besondere Herausforderung dar. Von besonderer Bedeutung ist die strukturelle Gestaltung des Waldes, um diesen widerstandsfähiger gegenüber Trockenstress zu machen. Forschungsergebnisse aus den letzten drei Jahrzehnten zeigen, dass Bäume, die an Waldrändern wachsen, besonders anfällig gegenüber Trockens...

Dial and vertical patterns of stem CO2 efflux are highly variable in tropical trees. Thus, tree level respiratory carbon fluxes remain a defective measure within the forest carbon budget. Vertical profile measurements of stem CO2 efflux (Estem) were conducted on a Scleronema micranthum tree growing in an old growth terra firme forest in the Central...

2017. Ecosystem dynamics and management after forest die-off: a global synthesis with conceptual state-and-transition models. Ecosphere 8(12): Abstract. Broad-scale forest die-off associated with drought and heat has now been reported from every forested continent, posing a global-scale challenge to forest management. Climate-driven die-off is freq...

Merkliche Folgen des Klimawandels sind vermehrte extreme Wetterereignisse. Extreme Trockenjahre wie das Jahr 2015 verlangen nach waldbaulichen Maßnahmen, um Kalamitäten vorzubeugen oder zu vermeiden. Oft empfohlen wird eine kurzfristige Hiebsmaßnahme zur Reduzierung der Bestockung: indem man die Blattfl äche des Bestandes verringert, reduziert man...

The Amazon forest is integral to the global climate system in part because of the high rate of rainfall recycling through tree transpiration and biodiversity (size and species composition). However, the partitioning of precipitation into evaporation, transpiration and runoff, has been quantified at only a few sites. At our study site in the central...

Reduced Impact Logging (RIL) is thought to be the most suitable, but also most politically discussed, method to exploit tropical forest ecosystems for timber. In this review we give an assessment of RIL from biodiversity, silvicultural and socio-economic perspectives. We first place RIL as a potential tool for retaining forest diversity and structu...

Daily xylem sap flux values (daily Js) and maximum xylem sap flux values (max Js) from 125 tropical trees from different study sites in the Neotropics were compared. A cross species and study site relationship was found between daily and maximum values. The relationship can be expressed as daily Js = 6.5 x max Js. The geometrical relationship betwe...

Großflächige Rodungen und nicht nachhaltige Waldwirtschaft führten in den letzten 80 Jahren zum Verlust der Hälfte aller tropischen Urwälder [1]. Dem liegt sowohl ein erhöhter Bedarf an landwirtschaftlicher Fläche als auch eine stetig wachsende Nachfrage an Holz zugrunde. Schnellwüchsige tropische Holzplantagen könnten der steigenden Nachfrage nach...

Newly created forest edges have significant ecophysiological effects on bordering trees. We studied edge effects on microclimate and tree transpiration rates during wet and dry seasons along a 250. m transect spanning the edge of an unpaved road into an old growth tropical lowland forest in the Central Brazilian Amazon. Canopy openness decreased on...

Key message In tropical forests, co-occurring woody monocot and dicot species adapted different water use strategies highly depending on their investment in the hydraulic conduit properties. Abstract We studied the hydraulic efficiency of palms and broad-leaved tropical tree species from a moist tropical lowland forest in the Central Brazilian Amaz...

The relationship between sap flux and stem CO2 efflux was assessed for three mango trees. We observed higher than expected CO2 effluxes at the place of measurement under intermediate sap flux velocities and lower fluxes under high sap flux velocity. This variation disappeared after removing the tree crown.ResumoA relação entre fluxo de seiva e eflu...

Native fruiting plants are widely cultivated in the Amazon, but little information on their water use characteristics can be found in the literature. To explore the potential impacts of plantations on local to regional water balance, we studied plant water use characteristics of two native fruit plants commonly occurring in the Amazon region. The s...

Tropical tree plantations usually consist of a single exotic fast growing species, but recent research describes positive effects on ecosystem functions from mixed tropical tree plantations. In this review, we present the current knowledge of drought resistance of tropical mixed species plantations and summarize preliminary evidence from a tree bio...

In the tropics, reforestations and agroforestry become increasingly important and may help mitigate climate change. However, high water use by trees may deplete water resources for associated crops or other purposes. Choice of tree species might reduce water use rates to acceptable levels, but available information on species-specific water use cha...

Old growth forests in the moist tropics are characterized by amazingly high tree species diversity with diverse species functionality. Despite the high species and functional diversity, tree water relations are commonly assumed to converge mainly with tree size. This relationship has been tested only in few tropical moist forests. Here we present d...

We studied tree water uptake patterns, tested for complementary water use among species and analysed controlling factors in a tropical tree diversity experiment. The water uptake depth of five species was investigated across seasons and diversity levels using the natural abundance of water isotopes and modeling. Three distinct water acquisition str...

Allometric models to estimate biomass components such as stem mass M s, foliage mass M l, root mass M r and aboveground mass M a, were developed for the palm species Euterpe precatoria Mart., which is the most abundant tree species in the Amazon. We harvested twenty palms including above-and below-ground parts in an old growth Amazonian forest in B...

Allometric models to estimate biomass components such as stem mass Ms, foliage mass Ml, root mass Mr and aboveground mass Ma, were developed for the palm species Euterpe precatoria Mart., which is the most abundant tree species in the Amazon. We harvested twenty palms including above- and below-ground parts in an old growth Amazonian forest in Braz...

Surface-to-atmosphere emissions of dimethyl sulfide (DMS) may impact global climate through the formation of gaseous sulfuric acid, which can yield secondary sulfate aerosols and contribute to new particle formation. While oceans are generally considered the dominant source of DMS, a shortage of ecosystem observations prevents an accurate analysis...

MY FIRST IMPRESSIONS OF THE TITLE roused doubts that the authors could efficiently cover such a broad topic as forest and global change for the variety of forests on our planet. My experience with earlier attempts to evaluate impacts of global change on for-ests was usually disappointing—most prior books focused on temperate forests while ignoring...

Light partitioning is often invoked as a mechanism for positive plant diversity effects on ecosystem functioning. Yet evidence for an improved distribution of foliage in space or time in diverse plant communities remains scarce, and restricted mostly to temperate grasslands. Here we identify the mechanisms through which tree species diversity affec...

Allometric models to estimate biomass components (leaves Ml, stem Ms, roots Mr and aboveground parts Ma) were developed for a palm species Euterpe precatoria Mart. that has been known as the most abundant woody species in the Amazon. We harvested twenty palms including above- and below-ground parts in an old growth Amazonian forest in Brazil. The d...

Light partitioning is often invoked as a mechanism for positive plant diversity effects on ecosystem functioning. Yet evidence for an improved distribution of foliage in space or time in diverse plant communities remains scarce, and restricted mostly to temperate grasslands. Here we identify the mechanisms through which tree species diversity affec...

We studied plant water use characteristics of the tree Theobroma grandiflorum (Cupuaçu, (Willd. ex Spreng.) Schum., Malvaceae) and the palm Euterpe precatoria (Açai, Mart., Arecaceae) both native to the Amazon and commonly occurring in the region. The tree species is occurring mainly in the terra firme forest whereas the palm species is restricted...

We report that the CO2 emitted from a stem is produced by physiological processes, but the challenge remains identifying what portion is produced by local tissues, which will facilitate much-needed mechanistic understanding of factors controlling autotrophic respiration.

Background/Question/Methods The influence of biodiversity on ecosystem functioning is now well established but our ability to predict the consequences of biodiversity changes remains limited by our poor understanding of the mechanisms underlying biodiversity effects. Light partitioning has been proposed as an example of complementarity among plan...

During summer and autumn 2007, a 11 GHz microwave radiometer was deployed in an experimental tree plantation in Sardinilla, Panama. With this instrument, the opacity of the tree canopy was derived from incoming brightness temperatures received on the ground. A collocated eddy-covariance flux tower measured water vapor fluxes and meteorological vari...

Evaluamos el efecto del flujo de la savia del xilema en la afluencia del CO2 radial en tejidos leñosos de una especie de árbol tropical en el centro de Manaos (Amazonas, Brasil). Un sistema de cámara abierta fue usado constantemente para medir cambios diarios en la afluencia del CO2 durante varios días. Al mismo tiempo, se midió el flujo de la savi...

1. Tree plantations play an important role in meeting the growing demand for wood, but there is concern about their high rates of water use. Recent approaches to reforestation in the tropics involve the establishment of multispecies plantations, but few studies have compared water use in mixed vs. monospecific stands. 2. We hypothesized that tree s...

1. Tree plantations play an important role in meeting the growing demand for wood, but there is concern about their high rates of water use. Recent approaches to reforestation in the tropics involve the establishment of multispecies plantations, but few studies have compared water use in mixed vs. monospecific stands. 2. We hypothesized that tree...

During summer and autumn 2007, a 11 GHz microwave radiometer was deployed in an experimental tree plantation in Sardinilla, Panama. The opacity of the tree canopy was derived from incoming brightness temperatures received on the ground. A collocated eddy-covariance flux tower measured water vapor fluxes and meteorological variables above the canopy...

Recent approaches to reforestation in the tropics emphasize the establishment of mixed species plantations to provide production but also ecological benefits. However, little is known about the effects of mixed-species stands on soil water utilization und tree water use rates. The objectives of this study were i) to asses seasonal plant water uptak...

We studied nine tree species with different leaf phenologies growing in monospecific plantations in the watershed of the Panama Canal. The annual rainfall in the region averages 2350 mm with a pronounced dry season from January to March. The atmospheric evaporative demand is usually higher in the dry season compared to the wet season. Our objective...