Physiological Plant Ecology (Kahmen)Head of Research Unit Prof. Dr.Ansgar KahmenOverviewMembersPublicationsProjects & CollaborationsProjects & Collaborations OverviewMembersPublicationsProjects & Collaborations Projects & Collaborations 26 foundShow per page10 10 20 50 From Bauhin to Lachenal: Enabling digital access to the historic 16th-18th century herbaria in Basel Research Project | 2 Project MembersThe scope of the project is enabling digital access to almost 10'000 singular historic (16th-18th century) herbarium specimens at the Herbaria Basel , by updating and expanding the digital information associated with five partially digitized, important historic herbaria following standards laid out in Frick & Greeff (2021). Meta-data for digital specimens will include all fields required for specimen filing and finding (physically, in the database, and online), such as collecting information (names, dates, administrative areas) and taxonomic information (determination, consistent name resolution, type status). This project is important because it promotes digital accessibility to important specimens : Accessibility and conservation of research-relevant data are a core task of herbaria and are within the scope of SwissCollNet. Our project mobilizes the information of close to 10'000 singular historic specimens and presents them online, besides via our institutional internet-portal (herbarium.unibas.ch, in development), also via Global Biodiversity Information Facility ( www.gbif.org ) and within the timeframe of the project also via Global Plants on JSTOR (plants.jstor.org). All data will also be integrated in the Swiss Virtual Natural History Collection portal (in development) by meeting established Swiss-wide standards. In the footsteps of Sarasin and Christ: digitization of fern collections at the herbaria in Basel and Zürich Research Project | 2 Project MembersThe world's herbaria document the diversity of plant life across the globe and through time. Many of the first descriptions of plants were based on material stemming from rather adventurous collection expeditions and remarkable personalities. Therefore, many historic collections are simultaneously of exceptional cultural, historic, and scientific value, often interwoven with colonial history. This is particularly true for tropical regions. The Sarasin cousins (Karl Friedrich (Fritz), 1859-1942; and Paul Benedict, 1856-1929) from Basel are such remarkable personalities with profound impacts both on cultural and natural history. Being born wealthy in the upper societal echelons of Basel, their gay love was taboo, prompting them to spend their fortunes to make a career as scientific explorers in Asia, primarily in Ceylon (now Sri Lanka), Celebes (now Sulawesi, Indonesia) and New Caledonia (incl. the loyalty Islands, where Fritz was the first-ever plant collector; Schär 2015). By traveling and collecting in the largely uncontacted interiors of these places collaborating with colonial rulers, their expeditions had a political note, but also resulted in profound impacts on natural history. The collecting expeditions of the Sarasin cousins resulted in rich collections; estimated at ca. 300'000 specimens of gastropods, arthropods, birds, mammals, and spiders, as well as 680 ethnographic objects and 600 photographs from Celebes alone (Schär 2015). These specimens form important parts of the collections of the Natural History Museum and Museum of Cultures in Basel. Strikingly less known, but equally important, are the estimated 3000 botanical collections of the Sarasin cousins. These specimens were sent back to Switzerland, where they were examined and identified by specialists, resulting in a flurry of new species. Hermann Christ (1833-1933) of Basel, the world's primary fern specialist at the time, despite being professionally a lawyer, described at least 36 fern species from Celebes alone ("Filices Sarisinianae", Christ, 1894-97). These plants were then donated to the Herbarium of the University of Basel, but remained unincorporated. In Zurich, Hans Schinz (1858-1941) and colleagues treated the angiosperms from New Caledonia, a significant part of which were then donated to Basel for reasons unknown. The importance of the Sarasin collections is underlined by regular re-discovery of Type material (e.g. Chen et al. 2021), always in association with Christ's previous work on these specimens. Overall, Christ's influence on fern taxonomy is paramount, already from his ca. 310 papers and ca. 1800 basionyms that he published. Asessing the drought response strategies of ten temperate tree species and their drought acclimation potential in a throughfall exclusion experiment in a mature forest Research Project | 5 Project MembersGlobal climate change and in particular changes in the hydroclimate towards dryer and warmer summers will impact the structure and composition of central European and other forests on the planet. The extremely hot and dry summers that Europe has experienced in 2003 and in 2018 have already demonstrated the severe impacts that a changing climate will have on tree and forest function and composition for these ecosystems. Critical mechanisms that determine how drought will impact the functioning of trees and forests are, however, poorly understood. This makes it difficult to anticipate the consequences of a future and dryer climate for key ecosystem functions and prevents the development of silvicultural management plants for more resistant and resilient forest ecosystems. Here we propose to close this gap and to address the effects of drought on mature trees from ten different temperate European species in a large-scale ecosystem manipulation experiment. From our work, we expect the following outcome: we will provide thefirst comprehensive empirical characterization of the drought response strategies of key temperate European tree species, we will identify the trait syndromes that govern the different drought response strategies in these species and will identify important tradeoffs between traits and function, we will provide one of the first large scale across-species assessments of the acclimation potential of mature temperate European tree species to reduced water availability and we will identify the key traits that are responsible for these acclimations. A novel through fall exclusion experiment to assess the physiological and biogeochemical consequences of precipitation changes for temperate forests (NF R'Equip) Research Project | 2 Project MembersRising global temperatures, fewer number of precipitation days and an increased intensity of drought events are projected to shape the future climate of central Europe. Changes in water availability and more intense drought events will have significant impacts on the central European vegetation and on temperate European forests in particular. Importantly, critical mechanisms that determine how changes in water availability and drought will impact the functioning of temperate European forests are poorly understood and not well represented in earth system models. Anticipating the consequences of a future climate for the functioning of temperate European forests is therefore difficult and hinders the design of mitigation options and future forest management plans. Most experiments that attempt to improve the mechanistic understanding of drought responses of terrestrial ecosystem have to date focused either on the experimental manipulation of grasslands or on investigations with tree seedlings or saplings. Although forests play an essential role for the delivery of ecosystem goods and services, very few experiments exist in established temperate European forests that mechanistically investigate the responses of mature trees and forest to changes in water availability or drought. To close this critical research gap, it is the goal of this proposal to establish an experimental research platform in a species rich and mature temperate forest in Switzerland. This experimental platform will provide the opportunity over the next two decades to host research projects addressing some of the most important unresolved questions with respect to tree and forests responses to changes in the precipitation regime and drought. Specifically, these projects will address the long-term acclimation potential of individual species or entire forests to precipitation changes, physiological and biogeochemical thresholds and tipping points during drought, and recovery processes during and after extended drought events. The experimental research platform that we seek to establish will combine a unique infrastructure that we request with this proposal. This infrastructure will include (i) a canopy crane that will allow scientific investigations in the canopy of more than 250 mature trees, (ii) six mobile roofs that will be installed 2.5 m above the ground and will cover a total area of 3398 m2 for the manipulation of precipitation inputs into the forest, and (iii) state of the art scientific instrumentation. Using millet-legume model intercropping systems to establish mycorrhiza-facilitated bioirrigation in dryland agriculture Research Project | 3 Project MembersIn the years to come, sustainable land use is one of the big challenges for plant science. One promising low-input strategy is to make use of the potential of intercropping. In dryland agriculture, deep-rooting plants, intercropped within shallow-rooting ones, may act as "bioirrigators" that can transfer water from deep soil layers to the topsoil for the benefit of the system. Our recent experiments have shown that bioirrigation is facilitated by the presence of arbuscular mycorrhizal fungi (AMF), which connect the intercropped plants by a common mycorrhizal network (CMN). The ambition of the research that we propose in this project is to identify the morphological, physiological and competitive traits that make plants ideal bioirrigators in CMN facilitated intercropping systems. With this research we seek to establish the basic knowledge that will allow establish effective CMN facilitated bioirrigation in intercropping systems as a measure to stabilize and increase the yield of small holder or subsistence farmers in dryland agriculture. Cold root effects on water-uptake and C-relations in temperate tree species Research Project | 2 Project MembersPrevious studies indicated that low root zone temperatures can induce drought-like water shortage in trees, with severe consequences also for their C-household. The restricted water conductivity of roots cannot be explained by the increased viscosity of water at cold temperatures alone. The very high sensitivity against non-freezing, colder root temperatures rather suggests that the water uptake of roots is likely stronger dependent on active processes (e.g. via aquaporins) than is generally assumed. Cold root temperature induced drought-like stress might thus contribute to the observed growth restriction of trees at their cold limits. In this 4-year PhD project, we will built upon recent experiments at the University of Basel to deepen our understanding of cold root zone effects on temperature trees. We will investigate seedlings of different temperate tree species at warm air temperatures and different root temperatures by means of a temperature-controlled water bath system. Water- and nitrogen-uptake, as well as carbon assimilation at different root temperatures will be quantified by pulse labelling with stable isotopes ( 2 H-H 2 O and 15 N-NO 3 enriched water, 13 C-CO 2 enriched air). Especially, we will address the following questions: Is the water uptake capacity of tree species with low elevational distribution limits more sensitive to low root zone temperatures than in species with high elevation distribution limits? Is the strong restriction of the phloem C-transport at cold root temperatures leading to accumulated non-structural carbohydrate (NSC) reserves in the aboveground tissue of tree seedlings? Are trees, which are raised at colder temperatures better adapted to low root zone temperatures in terms of water-uptake and -transport, than trees raised at warmer temperatures (test for long-term acclimatization)? Is the magnitude of nitrogen (N) uptake and -transport at cold root zone temperatures restricted to the same magnitude as the uptake of water? Besides detailed physiological insights in cold soil effects on the water, carbon and nutrient household of temperate tree species, this project will provide important information for climate-growth models of trees in general, and it will contribute quantitative data for mechanistic tree species distribution models. PRO-Alp. Plant reproduction of the alpine zone: disentangling ecological drivers of trait evolution Research Project | 2 Project MembersHow do plants adapt during major ecological transitions, such as evolutionary shifts between biomes? In particular, should we expect different plant species to adapt in similar ways to the same ecological challenges? And what specific aspects of ecological transitions drive phenotypic evolution? These are the motivating questions of the four-year project that addresses drivers of reproductive trait evolution in genera that radiated across elevational belts in multiple mountain systems. By reconstructing evolutionary trees (phylogenies) of these species, the project will link shifts in climatic niches to the evolution of plant traits, in particular flowers and inflorescences. By including tropical alpine, temperate alpine, and lowland species, we can reveal what specific aspects of climatic niches drive the evolution of plant form and plant reproduction. Multiple genera allow for addressing the extent to which species from different evolutionary backgrounds evolve similarly (convergently) along the same environmental gradients, helping us to understand whether studies of adaptation on few species can be generalized. That alpine species look different from lowland species is known to every Swiss person. Surprisingly, we still don't understand what specific aspects of high elevation ecosystems drive this striking trend in trait evolution. One problem in studying this problem is that the processes of adaptation are typically very slow, so experiments (e.g. transplant experiments or climatic modifications) may yield only limited information related to plasticity and evolution from standing genetic variation, ignoring trait evolution in deep evolutionary time. Therefore, this project uses plant diversity and radiations as "evolutionary experiments" by analyzing the phylogenies of species that are already adapted to diverse environments. ClimGrassHydro: Ecohydrology of mountain grassland under global change: mechanisms and consequences Research Project | 1 Project MembersIm Rahmen des Projektes sollen die individuellen und kombinierten Auswirkungen von unterschiedlichen Szenarien von Klimaerwärmung, erhöhten atmosphärischen CO2-Konzentrationen und Dürre auf die Ökohydrologie von bewirtschaftetem Grünland untersucht werden, insbesondere, wie sich wiederkehrende Dürreereignisse unter aktuellen und künftigen Klimabedingungen auf die dem Wasserhaushalt zugrundeliegenden Prozesse auswirken. Below-ground responses to manipulated snow cover duration and summer drought in alpine grassland (Acronym. bel-alp) Research Project | 2 Project MembersUsing a newly established infrastructure at 2500 m elevation in the central Alps, the proposed project aims at capitalizing on existing data on above-ground responses of alpine grassland to snow manipulation x summer drought by exploring below-ground responses. Since close to 80% of alpine biomass is below ground, measurable signals emerge slowly and potential effects are initially masked through the longevity of roots and storage organs. As the experiment will enter its fourth year in 2019, we will use in situ root imager to study root phenology, seasonal / annual fine root turnover, nutrient changes in soil solution and stable isotope labelled litter to track soil carbon and nutrients fluxes and pools, while continuing monitoring above-ground responses. Given the large size of test plots, we expect clear cut signals on whether and how changes in season length andsummer precipitation affect the most abundant type of alpine late successional vegetation. We await increasing season length to stimulate, but top-soil desiccation during summer drought to slow the carbon and nutrient cycle. We also expect that seasonal fine root dynamics are not in phase with leaf phenology, but continue throughout the snow-free period, despite and beyond pulsed leaf expansion. In a summer drought scenario, root production will be restricted to early and late season and will be shifted to deeper soil horizons. Graminoids are likely to cope better with such climatic shifts than dicot herbs, the contribution of which to NPP will diminish.The four-year project is designed for one PhD student (Patrick Möhl), who will complement the current works by Maria Vorkauf (PhD project funded by Mercator Foundation, Zürich-Basel Plant Science Center). Her PhD is entering its 3rd year (2018) and covered the pre-treatment period and the first two treatment seasons, with a focus on above-ground responses, including phenology. We envisage this project to establish for the first time the functional, high-time resolution interplay between above- and below-ground processes in a high elevation ecosystem, and it will contribute to a facts based projection of climatic change effects on the most abundant type of alpine vegetation in the Alps. Explore the 'upper hidden half' of trees: The influence of crown position on the seasonal dynamics of biological processes in the canopy of a temperate mixed forest Research Project | 3 Project MembersMost biological processes in trees are driven by the environmental conditions within the canopy. While the canopy surface is climatically closely connected to the free atmosphere, the vertical structure of tree crowns causes steep gradients in all environmental factors (e.g., light, temperature, wind, humidity) from the upper to the lowest canopy layer. Forest canopies thus provide vertically stratified micro-climates that exert very different impacts on all physiological processes at different canopy layers. Although this effect is well recognized, the difficult access to mature tree crowns generally prevents extensive, direct investigations. Consequently, biological processes in forest canopies, like evapotranspiration and productivity, are normally assessed as integrated values across the entire canopy, either for the whole tree via stem measurements, or for an entire forest area via flux towers. The new canopy crane at a species-rich temperate mixed forest in Hölstein, provides the ideal infrastructure to perform in situ measurements within the entire crown volume of a total of ca. 260 mature trees of ten different species. For the current project, it is proposed to conduct the first spatially and temporally highly-resolved investigations on growth, leaf gas exchange, carbon reserve dynamics and water relations along the environmental gradient in canopies of broad-leaved and conifer tree species. Throughout three consecutive years, the following biological processes and traits will be recorded on permanently marked branches at four different canopy layers: leaf phenology, shoot growth and secondary branch growth, net leaf CO 2 -exchange, non-structural carbohydrate tissue concentrations, stomatal conductance and branch water potentials. The micro-climatic variability (radiation, temperature and humidity) within the canopy will be recorded at multiple sites along vertical crown profiles in different species, which will enable to correlate the observed processes and traits in branches to the local environmental conditions. By further accounting for the spatial tree distribution at the site, all processes dynamics measured for individual trees, can be extrapolated to the three-dimensional forest canopy. In addition, dendrometer measurements at the main stems will allow to compare measurements of processes at different canopy layers with the integrative signals recorded at the stem-level (e.g., stem radius increment vs. phenology and branch growth, tree water deficit vs. branch water potentials). By simultaneously investigating growth, carbon- and water-relations directly within the canopy of different tree species, this project will reveal closer insights in the functional interrelations of these processes that are key to understanding tree responses to environmental stresses, like drought. The explicit consideration of differences along the environmental gradient in the canopies will deliver three-dimensional information of the observed processes, which will be also necessary for the development of more realistic dynamic tree growth models. 123 123 OverviewMembersPublicationsProjects & Collaborations
Projects & Collaborations 26 foundShow per page10 10 20 50 From Bauhin to Lachenal: Enabling digital access to the historic 16th-18th century herbaria in Basel Research Project | 2 Project MembersThe scope of the project is enabling digital access to almost 10'000 singular historic (16th-18th century) herbarium specimens at the Herbaria Basel , by updating and expanding the digital information associated with five partially digitized, important historic herbaria following standards laid out in Frick & Greeff (2021). Meta-data for digital specimens will include all fields required for specimen filing and finding (physically, in the database, and online), such as collecting information (names, dates, administrative areas) and taxonomic information (determination, consistent name resolution, type status). This project is important because it promotes digital accessibility to important specimens : Accessibility and conservation of research-relevant data are a core task of herbaria and are within the scope of SwissCollNet. Our project mobilizes the information of close to 10'000 singular historic specimens and presents them online, besides via our institutional internet-portal (herbarium.unibas.ch, in development), also via Global Biodiversity Information Facility ( www.gbif.org ) and within the timeframe of the project also via Global Plants on JSTOR (plants.jstor.org). All data will also be integrated in the Swiss Virtual Natural History Collection portal (in development) by meeting established Swiss-wide standards. In the footsteps of Sarasin and Christ: digitization of fern collections at the herbaria in Basel and Zürich Research Project | 2 Project MembersThe world's herbaria document the diversity of plant life across the globe and through time. Many of the first descriptions of plants were based on material stemming from rather adventurous collection expeditions and remarkable personalities. Therefore, many historic collections are simultaneously of exceptional cultural, historic, and scientific value, often interwoven with colonial history. This is particularly true for tropical regions. The Sarasin cousins (Karl Friedrich (Fritz), 1859-1942; and Paul Benedict, 1856-1929) from Basel are such remarkable personalities with profound impacts both on cultural and natural history. Being born wealthy in the upper societal echelons of Basel, their gay love was taboo, prompting them to spend their fortunes to make a career as scientific explorers in Asia, primarily in Ceylon (now Sri Lanka), Celebes (now Sulawesi, Indonesia) and New Caledonia (incl. the loyalty Islands, where Fritz was the first-ever plant collector; Schär 2015). By traveling and collecting in the largely uncontacted interiors of these places collaborating with colonial rulers, their expeditions had a political note, but also resulted in profound impacts on natural history. The collecting expeditions of the Sarasin cousins resulted in rich collections; estimated at ca. 300'000 specimens of gastropods, arthropods, birds, mammals, and spiders, as well as 680 ethnographic objects and 600 photographs from Celebes alone (Schär 2015). These specimens form important parts of the collections of the Natural History Museum and Museum of Cultures in Basel. Strikingly less known, but equally important, are the estimated 3000 botanical collections of the Sarasin cousins. These specimens were sent back to Switzerland, where they were examined and identified by specialists, resulting in a flurry of new species. Hermann Christ (1833-1933) of Basel, the world's primary fern specialist at the time, despite being professionally a lawyer, described at least 36 fern species from Celebes alone ("Filices Sarisinianae", Christ, 1894-97). These plants were then donated to the Herbarium of the University of Basel, but remained unincorporated. In Zurich, Hans Schinz (1858-1941) and colleagues treated the angiosperms from New Caledonia, a significant part of which were then donated to Basel for reasons unknown. The importance of the Sarasin collections is underlined by regular re-discovery of Type material (e.g. Chen et al. 2021), always in association with Christ's previous work on these specimens. Overall, Christ's influence on fern taxonomy is paramount, already from his ca. 310 papers and ca. 1800 basionyms that he published. Asessing the drought response strategies of ten temperate tree species and their drought acclimation potential in a throughfall exclusion experiment in a mature forest Research Project | 5 Project MembersGlobal climate change and in particular changes in the hydroclimate towards dryer and warmer summers will impact the structure and composition of central European and other forests on the planet. The extremely hot and dry summers that Europe has experienced in 2003 and in 2018 have already demonstrated the severe impacts that a changing climate will have on tree and forest function and composition for these ecosystems. Critical mechanisms that determine how drought will impact the functioning of trees and forests are, however, poorly understood. This makes it difficult to anticipate the consequences of a future and dryer climate for key ecosystem functions and prevents the development of silvicultural management plants for more resistant and resilient forest ecosystems. Here we propose to close this gap and to address the effects of drought on mature trees from ten different temperate European species in a large-scale ecosystem manipulation experiment. From our work, we expect the following outcome: we will provide thefirst comprehensive empirical characterization of the drought response strategies of key temperate European tree species, we will identify the trait syndromes that govern the different drought response strategies in these species and will identify important tradeoffs between traits and function, we will provide one of the first large scale across-species assessments of the acclimation potential of mature temperate European tree species to reduced water availability and we will identify the key traits that are responsible for these acclimations. A novel through fall exclusion experiment to assess the physiological and biogeochemical consequences of precipitation changes for temperate forests (NF R'Equip) Research Project | 2 Project MembersRising global temperatures, fewer number of precipitation days and an increased intensity of drought events are projected to shape the future climate of central Europe. Changes in water availability and more intense drought events will have significant impacts on the central European vegetation and on temperate European forests in particular. Importantly, critical mechanisms that determine how changes in water availability and drought will impact the functioning of temperate European forests are poorly understood and not well represented in earth system models. Anticipating the consequences of a future climate for the functioning of temperate European forests is therefore difficult and hinders the design of mitigation options and future forest management plans. Most experiments that attempt to improve the mechanistic understanding of drought responses of terrestrial ecosystem have to date focused either on the experimental manipulation of grasslands or on investigations with tree seedlings or saplings. Although forests play an essential role for the delivery of ecosystem goods and services, very few experiments exist in established temperate European forests that mechanistically investigate the responses of mature trees and forest to changes in water availability or drought. To close this critical research gap, it is the goal of this proposal to establish an experimental research platform in a species rich and mature temperate forest in Switzerland. This experimental platform will provide the opportunity over the next two decades to host research projects addressing some of the most important unresolved questions with respect to tree and forests responses to changes in the precipitation regime and drought. Specifically, these projects will address the long-term acclimation potential of individual species or entire forests to precipitation changes, physiological and biogeochemical thresholds and tipping points during drought, and recovery processes during and after extended drought events. The experimental research platform that we seek to establish will combine a unique infrastructure that we request with this proposal. This infrastructure will include (i) a canopy crane that will allow scientific investigations in the canopy of more than 250 mature trees, (ii) six mobile roofs that will be installed 2.5 m above the ground and will cover a total area of 3398 m2 for the manipulation of precipitation inputs into the forest, and (iii) state of the art scientific instrumentation. Using millet-legume model intercropping systems to establish mycorrhiza-facilitated bioirrigation in dryland agriculture Research Project | 3 Project MembersIn the years to come, sustainable land use is one of the big challenges for plant science. One promising low-input strategy is to make use of the potential of intercropping. In dryland agriculture, deep-rooting plants, intercropped within shallow-rooting ones, may act as "bioirrigators" that can transfer water from deep soil layers to the topsoil for the benefit of the system. Our recent experiments have shown that bioirrigation is facilitated by the presence of arbuscular mycorrhizal fungi (AMF), which connect the intercropped plants by a common mycorrhizal network (CMN). The ambition of the research that we propose in this project is to identify the morphological, physiological and competitive traits that make plants ideal bioirrigators in CMN facilitated intercropping systems. With this research we seek to establish the basic knowledge that will allow establish effective CMN facilitated bioirrigation in intercropping systems as a measure to stabilize and increase the yield of small holder or subsistence farmers in dryland agriculture. Cold root effects on water-uptake and C-relations in temperate tree species Research Project | 2 Project MembersPrevious studies indicated that low root zone temperatures can induce drought-like water shortage in trees, with severe consequences also for their C-household. The restricted water conductivity of roots cannot be explained by the increased viscosity of water at cold temperatures alone. The very high sensitivity against non-freezing, colder root temperatures rather suggests that the water uptake of roots is likely stronger dependent on active processes (e.g. via aquaporins) than is generally assumed. Cold root temperature induced drought-like stress might thus contribute to the observed growth restriction of trees at their cold limits. In this 4-year PhD project, we will built upon recent experiments at the University of Basel to deepen our understanding of cold root zone effects on temperature trees. We will investigate seedlings of different temperate tree species at warm air temperatures and different root temperatures by means of a temperature-controlled water bath system. Water- and nitrogen-uptake, as well as carbon assimilation at different root temperatures will be quantified by pulse labelling with stable isotopes ( 2 H-H 2 O and 15 N-NO 3 enriched water, 13 C-CO 2 enriched air). Especially, we will address the following questions: Is the water uptake capacity of tree species with low elevational distribution limits more sensitive to low root zone temperatures than in species with high elevation distribution limits? Is the strong restriction of the phloem C-transport at cold root temperatures leading to accumulated non-structural carbohydrate (NSC) reserves in the aboveground tissue of tree seedlings? Are trees, which are raised at colder temperatures better adapted to low root zone temperatures in terms of water-uptake and -transport, than trees raised at warmer temperatures (test for long-term acclimatization)? Is the magnitude of nitrogen (N) uptake and -transport at cold root zone temperatures restricted to the same magnitude as the uptake of water? Besides detailed physiological insights in cold soil effects on the water, carbon and nutrient household of temperate tree species, this project will provide important information for climate-growth models of trees in general, and it will contribute quantitative data for mechanistic tree species distribution models. PRO-Alp. Plant reproduction of the alpine zone: disentangling ecological drivers of trait evolution Research Project | 2 Project MembersHow do plants adapt during major ecological transitions, such as evolutionary shifts between biomes? In particular, should we expect different plant species to adapt in similar ways to the same ecological challenges? And what specific aspects of ecological transitions drive phenotypic evolution? These are the motivating questions of the four-year project that addresses drivers of reproductive trait evolution in genera that radiated across elevational belts in multiple mountain systems. By reconstructing evolutionary trees (phylogenies) of these species, the project will link shifts in climatic niches to the evolution of plant traits, in particular flowers and inflorescences. By including tropical alpine, temperate alpine, and lowland species, we can reveal what specific aspects of climatic niches drive the evolution of plant form and plant reproduction. Multiple genera allow for addressing the extent to which species from different evolutionary backgrounds evolve similarly (convergently) along the same environmental gradients, helping us to understand whether studies of adaptation on few species can be generalized. That alpine species look different from lowland species is known to every Swiss person. Surprisingly, we still don't understand what specific aspects of high elevation ecosystems drive this striking trend in trait evolution. One problem in studying this problem is that the processes of adaptation are typically very slow, so experiments (e.g. transplant experiments or climatic modifications) may yield only limited information related to plasticity and evolution from standing genetic variation, ignoring trait evolution in deep evolutionary time. Therefore, this project uses plant diversity and radiations as "evolutionary experiments" by analyzing the phylogenies of species that are already adapted to diverse environments. ClimGrassHydro: Ecohydrology of mountain grassland under global change: mechanisms and consequences Research Project | 1 Project MembersIm Rahmen des Projektes sollen die individuellen und kombinierten Auswirkungen von unterschiedlichen Szenarien von Klimaerwärmung, erhöhten atmosphärischen CO2-Konzentrationen und Dürre auf die Ökohydrologie von bewirtschaftetem Grünland untersucht werden, insbesondere, wie sich wiederkehrende Dürreereignisse unter aktuellen und künftigen Klimabedingungen auf die dem Wasserhaushalt zugrundeliegenden Prozesse auswirken. Below-ground responses to manipulated snow cover duration and summer drought in alpine grassland (Acronym. bel-alp) Research Project | 2 Project MembersUsing a newly established infrastructure at 2500 m elevation in the central Alps, the proposed project aims at capitalizing on existing data on above-ground responses of alpine grassland to snow manipulation x summer drought by exploring below-ground responses. Since close to 80% of alpine biomass is below ground, measurable signals emerge slowly and potential effects are initially masked through the longevity of roots and storage organs. As the experiment will enter its fourth year in 2019, we will use in situ root imager to study root phenology, seasonal / annual fine root turnover, nutrient changes in soil solution and stable isotope labelled litter to track soil carbon and nutrients fluxes and pools, while continuing monitoring above-ground responses. Given the large size of test plots, we expect clear cut signals on whether and how changes in season length andsummer precipitation affect the most abundant type of alpine late successional vegetation. We await increasing season length to stimulate, but top-soil desiccation during summer drought to slow the carbon and nutrient cycle. We also expect that seasonal fine root dynamics are not in phase with leaf phenology, but continue throughout the snow-free period, despite and beyond pulsed leaf expansion. In a summer drought scenario, root production will be restricted to early and late season and will be shifted to deeper soil horizons. Graminoids are likely to cope better with such climatic shifts than dicot herbs, the contribution of which to NPP will diminish.The four-year project is designed for one PhD student (Patrick Möhl), who will complement the current works by Maria Vorkauf (PhD project funded by Mercator Foundation, Zürich-Basel Plant Science Center). Her PhD is entering its 3rd year (2018) and covered the pre-treatment period and the first two treatment seasons, with a focus on above-ground responses, including phenology. We envisage this project to establish for the first time the functional, high-time resolution interplay between above- and below-ground processes in a high elevation ecosystem, and it will contribute to a facts based projection of climatic change effects on the most abundant type of alpine vegetation in the Alps. Explore the 'upper hidden half' of trees: The influence of crown position on the seasonal dynamics of biological processes in the canopy of a temperate mixed forest Research Project | 3 Project MembersMost biological processes in trees are driven by the environmental conditions within the canopy. While the canopy surface is climatically closely connected to the free atmosphere, the vertical structure of tree crowns causes steep gradients in all environmental factors (e.g., light, temperature, wind, humidity) from the upper to the lowest canopy layer. Forest canopies thus provide vertically stratified micro-climates that exert very different impacts on all physiological processes at different canopy layers. Although this effect is well recognized, the difficult access to mature tree crowns generally prevents extensive, direct investigations. Consequently, biological processes in forest canopies, like evapotranspiration and productivity, are normally assessed as integrated values across the entire canopy, either for the whole tree via stem measurements, or for an entire forest area via flux towers. The new canopy crane at a species-rich temperate mixed forest in Hölstein, provides the ideal infrastructure to perform in situ measurements within the entire crown volume of a total of ca. 260 mature trees of ten different species. For the current project, it is proposed to conduct the first spatially and temporally highly-resolved investigations on growth, leaf gas exchange, carbon reserve dynamics and water relations along the environmental gradient in canopies of broad-leaved and conifer tree species. Throughout three consecutive years, the following biological processes and traits will be recorded on permanently marked branches at four different canopy layers: leaf phenology, shoot growth and secondary branch growth, net leaf CO 2 -exchange, non-structural carbohydrate tissue concentrations, stomatal conductance and branch water potentials. The micro-climatic variability (radiation, temperature and humidity) within the canopy will be recorded at multiple sites along vertical crown profiles in different species, which will enable to correlate the observed processes and traits in branches to the local environmental conditions. By further accounting for the spatial tree distribution at the site, all processes dynamics measured for individual trees, can be extrapolated to the three-dimensional forest canopy. In addition, dendrometer measurements at the main stems will allow to compare measurements of processes at different canopy layers with the integrative signals recorded at the stem-level (e.g., stem radius increment vs. phenology and branch growth, tree water deficit vs. branch water potentials). By simultaneously investigating growth, carbon- and water-relations directly within the canopy of different tree species, this project will reveal closer insights in the functional interrelations of these processes that are key to understanding tree responses to environmental stresses, like drought. The explicit consideration of differences along the environmental gradient in the canopies will deliver three-dimensional information of the observed processes, which will be also necessary for the development of more realistic dynamic tree growth models. 123 123
From Bauhin to Lachenal: Enabling digital access to the historic 16th-18th century herbaria in Basel Research Project | 2 Project MembersThe scope of the project is enabling digital access to almost 10'000 singular historic (16th-18th century) herbarium specimens at the Herbaria Basel , by updating and expanding the digital information associated with five partially digitized, important historic herbaria following standards laid out in Frick & Greeff (2021). Meta-data for digital specimens will include all fields required for specimen filing and finding (physically, in the database, and online), such as collecting information (names, dates, administrative areas) and taxonomic information (determination, consistent name resolution, type status). This project is important because it promotes digital accessibility to important specimens : Accessibility and conservation of research-relevant data are a core task of herbaria and are within the scope of SwissCollNet. Our project mobilizes the information of close to 10'000 singular historic specimens and presents them online, besides via our institutional internet-portal (herbarium.unibas.ch, in development), also via Global Biodiversity Information Facility ( www.gbif.org ) and within the timeframe of the project also via Global Plants on JSTOR (plants.jstor.org). All data will also be integrated in the Swiss Virtual Natural History Collection portal (in development) by meeting established Swiss-wide standards.
In the footsteps of Sarasin and Christ: digitization of fern collections at the herbaria in Basel and Zürich Research Project | 2 Project MembersThe world's herbaria document the diversity of plant life across the globe and through time. Many of the first descriptions of plants were based on material stemming from rather adventurous collection expeditions and remarkable personalities. Therefore, many historic collections are simultaneously of exceptional cultural, historic, and scientific value, often interwoven with colonial history. This is particularly true for tropical regions. The Sarasin cousins (Karl Friedrich (Fritz), 1859-1942; and Paul Benedict, 1856-1929) from Basel are such remarkable personalities with profound impacts both on cultural and natural history. Being born wealthy in the upper societal echelons of Basel, their gay love was taboo, prompting them to spend their fortunes to make a career as scientific explorers in Asia, primarily in Ceylon (now Sri Lanka), Celebes (now Sulawesi, Indonesia) and New Caledonia (incl. the loyalty Islands, where Fritz was the first-ever plant collector; Schär 2015). By traveling and collecting in the largely uncontacted interiors of these places collaborating with colonial rulers, their expeditions had a political note, but also resulted in profound impacts on natural history. The collecting expeditions of the Sarasin cousins resulted in rich collections; estimated at ca. 300'000 specimens of gastropods, arthropods, birds, mammals, and spiders, as well as 680 ethnographic objects and 600 photographs from Celebes alone (Schär 2015). These specimens form important parts of the collections of the Natural History Museum and Museum of Cultures in Basel. Strikingly less known, but equally important, are the estimated 3000 botanical collections of the Sarasin cousins. These specimens were sent back to Switzerland, where they were examined and identified by specialists, resulting in a flurry of new species. Hermann Christ (1833-1933) of Basel, the world's primary fern specialist at the time, despite being professionally a lawyer, described at least 36 fern species from Celebes alone ("Filices Sarisinianae", Christ, 1894-97). These plants were then donated to the Herbarium of the University of Basel, but remained unincorporated. In Zurich, Hans Schinz (1858-1941) and colleagues treated the angiosperms from New Caledonia, a significant part of which were then donated to Basel for reasons unknown. The importance of the Sarasin collections is underlined by regular re-discovery of Type material (e.g. Chen et al. 2021), always in association with Christ's previous work on these specimens. Overall, Christ's influence on fern taxonomy is paramount, already from his ca. 310 papers and ca. 1800 basionyms that he published.
Asessing the drought response strategies of ten temperate tree species and their drought acclimation potential in a throughfall exclusion experiment in a mature forest Research Project | 5 Project MembersGlobal climate change and in particular changes in the hydroclimate towards dryer and warmer summers will impact the structure and composition of central European and other forests on the planet. The extremely hot and dry summers that Europe has experienced in 2003 and in 2018 have already demonstrated the severe impacts that a changing climate will have on tree and forest function and composition for these ecosystems. Critical mechanisms that determine how drought will impact the functioning of trees and forests are, however, poorly understood. This makes it difficult to anticipate the consequences of a future and dryer climate for key ecosystem functions and prevents the development of silvicultural management plants for more resistant and resilient forest ecosystems. Here we propose to close this gap and to address the effects of drought on mature trees from ten different temperate European species in a large-scale ecosystem manipulation experiment. From our work, we expect the following outcome: we will provide thefirst comprehensive empirical characterization of the drought response strategies of key temperate European tree species, we will identify the trait syndromes that govern the different drought response strategies in these species and will identify important tradeoffs between traits and function, we will provide one of the first large scale across-species assessments of the acclimation potential of mature temperate European tree species to reduced water availability and we will identify the key traits that are responsible for these acclimations.
A novel through fall exclusion experiment to assess the physiological and biogeochemical consequences of precipitation changes for temperate forests (NF R'Equip) Research Project | 2 Project MembersRising global temperatures, fewer number of precipitation days and an increased intensity of drought events are projected to shape the future climate of central Europe. Changes in water availability and more intense drought events will have significant impacts on the central European vegetation and on temperate European forests in particular. Importantly, critical mechanisms that determine how changes in water availability and drought will impact the functioning of temperate European forests are poorly understood and not well represented in earth system models. Anticipating the consequences of a future climate for the functioning of temperate European forests is therefore difficult and hinders the design of mitigation options and future forest management plans. Most experiments that attempt to improve the mechanistic understanding of drought responses of terrestrial ecosystem have to date focused either on the experimental manipulation of grasslands or on investigations with tree seedlings or saplings. Although forests play an essential role for the delivery of ecosystem goods and services, very few experiments exist in established temperate European forests that mechanistically investigate the responses of mature trees and forest to changes in water availability or drought. To close this critical research gap, it is the goal of this proposal to establish an experimental research platform in a species rich and mature temperate forest in Switzerland. This experimental platform will provide the opportunity over the next two decades to host research projects addressing some of the most important unresolved questions with respect to tree and forests responses to changes in the precipitation regime and drought. Specifically, these projects will address the long-term acclimation potential of individual species or entire forests to precipitation changes, physiological and biogeochemical thresholds and tipping points during drought, and recovery processes during and after extended drought events. The experimental research platform that we seek to establish will combine a unique infrastructure that we request with this proposal. This infrastructure will include (i) a canopy crane that will allow scientific investigations in the canopy of more than 250 mature trees, (ii) six mobile roofs that will be installed 2.5 m above the ground and will cover a total area of 3398 m2 for the manipulation of precipitation inputs into the forest, and (iii) state of the art scientific instrumentation.
Using millet-legume model intercropping systems to establish mycorrhiza-facilitated bioirrigation in dryland agriculture Research Project | 3 Project MembersIn the years to come, sustainable land use is one of the big challenges for plant science. One promising low-input strategy is to make use of the potential of intercropping. In dryland agriculture, deep-rooting plants, intercropped within shallow-rooting ones, may act as "bioirrigators" that can transfer water from deep soil layers to the topsoil for the benefit of the system. Our recent experiments have shown that bioirrigation is facilitated by the presence of arbuscular mycorrhizal fungi (AMF), which connect the intercropped plants by a common mycorrhizal network (CMN). The ambition of the research that we propose in this project is to identify the morphological, physiological and competitive traits that make plants ideal bioirrigators in CMN facilitated intercropping systems. With this research we seek to establish the basic knowledge that will allow establish effective CMN facilitated bioirrigation in intercropping systems as a measure to stabilize and increase the yield of small holder or subsistence farmers in dryland agriculture.
Cold root effects on water-uptake and C-relations in temperate tree species Research Project | 2 Project MembersPrevious studies indicated that low root zone temperatures can induce drought-like water shortage in trees, with severe consequences also for their C-household. The restricted water conductivity of roots cannot be explained by the increased viscosity of water at cold temperatures alone. The very high sensitivity against non-freezing, colder root temperatures rather suggests that the water uptake of roots is likely stronger dependent on active processes (e.g. via aquaporins) than is generally assumed. Cold root temperature induced drought-like stress might thus contribute to the observed growth restriction of trees at their cold limits. In this 4-year PhD project, we will built upon recent experiments at the University of Basel to deepen our understanding of cold root zone effects on temperature trees. We will investigate seedlings of different temperate tree species at warm air temperatures and different root temperatures by means of a temperature-controlled water bath system. Water- and nitrogen-uptake, as well as carbon assimilation at different root temperatures will be quantified by pulse labelling with stable isotopes ( 2 H-H 2 O and 15 N-NO 3 enriched water, 13 C-CO 2 enriched air). Especially, we will address the following questions: Is the water uptake capacity of tree species with low elevational distribution limits more sensitive to low root zone temperatures than in species with high elevation distribution limits? Is the strong restriction of the phloem C-transport at cold root temperatures leading to accumulated non-structural carbohydrate (NSC) reserves in the aboveground tissue of tree seedlings? Are trees, which are raised at colder temperatures better adapted to low root zone temperatures in terms of water-uptake and -transport, than trees raised at warmer temperatures (test for long-term acclimatization)? Is the magnitude of nitrogen (N) uptake and -transport at cold root zone temperatures restricted to the same magnitude as the uptake of water? Besides detailed physiological insights in cold soil effects on the water, carbon and nutrient household of temperate tree species, this project will provide important information for climate-growth models of trees in general, and it will contribute quantitative data for mechanistic tree species distribution models.
PRO-Alp. Plant reproduction of the alpine zone: disentangling ecological drivers of trait evolution Research Project | 2 Project MembersHow do plants adapt during major ecological transitions, such as evolutionary shifts between biomes? In particular, should we expect different plant species to adapt in similar ways to the same ecological challenges? And what specific aspects of ecological transitions drive phenotypic evolution? These are the motivating questions of the four-year project that addresses drivers of reproductive trait evolution in genera that radiated across elevational belts in multiple mountain systems. By reconstructing evolutionary trees (phylogenies) of these species, the project will link shifts in climatic niches to the evolution of plant traits, in particular flowers and inflorescences. By including tropical alpine, temperate alpine, and lowland species, we can reveal what specific aspects of climatic niches drive the evolution of plant form and plant reproduction. Multiple genera allow for addressing the extent to which species from different evolutionary backgrounds evolve similarly (convergently) along the same environmental gradients, helping us to understand whether studies of adaptation on few species can be generalized. That alpine species look different from lowland species is known to every Swiss person. Surprisingly, we still don't understand what specific aspects of high elevation ecosystems drive this striking trend in trait evolution. One problem in studying this problem is that the processes of adaptation are typically very slow, so experiments (e.g. transplant experiments or climatic modifications) may yield only limited information related to plasticity and evolution from standing genetic variation, ignoring trait evolution in deep evolutionary time. Therefore, this project uses plant diversity and radiations as "evolutionary experiments" by analyzing the phylogenies of species that are already adapted to diverse environments.
ClimGrassHydro: Ecohydrology of mountain grassland under global change: mechanisms and consequences Research Project | 1 Project MembersIm Rahmen des Projektes sollen die individuellen und kombinierten Auswirkungen von unterschiedlichen Szenarien von Klimaerwärmung, erhöhten atmosphärischen CO2-Konzentrationen und Dürre auf die Ökohydrologie von bewirtschaftetem Grünland untersucht werden, insbesondere, wie sich wiederkehrende Dürreereignisse unter aktuellen und künftigen Klimabedingungen auf die dem Wasserhaushalt zugrundeliegenden Prozesse auswirken.
Below-ground responses to manipulated snow cover duration and summer drought in alpine grassland (Acronym. bel-alp) Research Project | 2 Project MembersUsing a newly established infrastructure at 2500 m elevation in the central Alps, the proposed project aims at capitalizing on existing data on above-ground responses of alpine grassland to snow manipulation x summer drought by exploring below-ground responses. Since close to 80% of alpine biomass is below ground, measurable signals emerge slowly and potential effects are initially masked through the longevity of roots and storage organs. As the experiment will enter its fourth year in 2019, we will use in situ root imager to study root phenology, seasonal / annual fine root turnover, nutrient changes in soil solution and stable isotope labelled litter to track soil carbon and nutrients fluxes and pools, while continuing monitoring above-ground responses. Given the large size of test plots, we expect clear cut signals on whether and how changes in season length andsummer precipitation affect the most abundant type of alpine late successional vegetation. We await increasing season length to stimulate, but top-soil desiccation during summer drought to slow the carbon and nutrient cycle. We also expect that seasonal fine root dynamics are not in phase with leaf phenology, but continue throughout the snow-free period, despite and beyond pulsed leaf expansion. In a summer drought scenario, root production will be restricted to early and late season and will be shifted to deeper soil horizons. Graminoids are likely to cope better with such climatic shifts than dicot herbs, the contribution of which to NPP will diminish.The four-year project is designed for one PhD student (Patrick Möhl), who will complement the current works by Maria Vorkauf (PhD project funded by Mercator Foundation, Zürich-Basel Plant Science Center). Her PhD is entering its 3rd year (2018) and covered the pre-treatment period and the first two treatment seasons, with a focus on above-ground responses, including phenology. We envisage this project to establish for the first time the functional, high-time resolution interplay between above- and below-ground processes in a high elevation ecosystem, and it will contribute to a facts based projection of climatic change effects on the most abundant type of alpine vegetation in the Alps.
Explore the 'upper hidden half' of trees: The influence of crown position on the seasonal dynamics of biological processes in the canopy of a temperate mixed forest Research Project | 3 Project MembersMost biological processes in trees are driven by the environmental conditions within the canopy. While the canopy surface is climatically closely connected to the free atmosphere, the vertical structure of tree crowns causes steep gradients in all environmental factors (e.g., light, temperature, wind, humidity) from the upper to the lowest canopy layer. Forest canopies thus provide vertically stratified micro-climates that exert very different impacts on all physiological processes at different canopy layers. Although this effect is well recognized, the difficult access to mature tree crowns generally prevents extensive, direct investigations. Consequently, biological processes in forest canopies, like evapotranspiration and productivity, are normally assessed as integrated values across the entire canopy, either for the whole tree via stem measurements, or for an entire forest area via flux towers. The new canopy crane at a species-rich temperate mixed forest in Hölstein, provides the ideal infrastructure to perform in situ measurements within the entire crown volume of a total of ca. 260 mature trees of ten different species. For the current project, it is proposed to conduct the first spatially and temporally highly-resolved investigations on growth, leaf gas exchange, carbon reserve dynamics and water relations along the environmental gradient in canopies of broad-leaved and conifer tree species. Throughout three consecutive years, the following biological processes and traits will be recorded on permanently marked branches at four different canopy layers: leaf phenology, shoot growth and secondary branch growth, net leaf CO 2 -exchange, non-structural carbohydrate tissue concentrations, stomatal conductance and branch water potentials. The micro-climatic variability (radiation, temperature and humidity) within the canopy will be recorded at multiple sites along vertical crown profiles in different species, which will enable to correlate the observed processes and traits in branches to the local environmental conditions. By further accounting for the spatial tree distribution at the site, all processes dynamics measured for individual trees, can be extrapolated to the three-dimensional forest canopy. In addition, dendrometer measurements at the main stems will allow to compare measurements of processes at different canopy layers with the integrative signals recorded at the stem-level (e.g., stem radius increment vs. phenology and branch growth, tree water deficit vs. branch water potentials). By simultaneously investigating growth, carbon- and water-relations directly within the canopy of different tree species, this project will reveal closer insights in the functional interrelations of these processes that are key to understanding tree responses to environmental stresses, like drought. The explicit consideration of differences along the environmental gradient in the canopies will deliver three-dimensional information of the observed processes, which will be also necessary for the development of more realistic dynamic tree growth models.
