2,237 research outputs found
Growth and resilience responses of Scots pine to extreme droughts across Europe depend on preâdrought growth conditions
Global climate change is expected to further raise the frequency and severity of extreme events, such as droughts. The effects of extreme droughts on trees are difficult to disentangle given the inherent complexity of drought events (frequency, severity, duration, and timing during the growing season). Besides, drought effects might be modulated by treesâ phenotypic variability, which is, in turn, affected by longâterm local selective pressures and management legacies. Here, we investigated the magnitude and the temporal changes of treeâlevel resilience (i.e., resistance, recovery, and resilience) to extreme droughts. Moreover, we assessed the treeâ, siteâ, and droughtârelated factors and their interactions driving the treeâlevel resilience to extreme droughts. We used a treeâring network of the widely distributed Scots pine (Pinus sylvestris ) along a 2800 km latitudinal gradient from southern Spain to northern Germany. We found that the resilience to extreme drought decreased in midâelevation and low productivity sites from 1980â1999 to 2000â2011 likely due to more frequent and severe droughts in the later period. Our study showed that the impact of drought on treeâlevel resilience was not dependent on its latitudinal location, but rather on the type of sites trees were growing at and on their growth performances (i.e., magnitude and variability of growth) during the preâdrought period. We found significant interactive effects between drought duration and tree growth prior to drought, suggesting that Scots pine trees with higher magnitude and variability of growth in the long term are more vulnerable to long and severe droughts. Moreover, our results indicate that Scots pine trees that experienced more frequent droughts over the longâterm were less resistant to extreme droughts. We therefore conclude that the physiological resilience to extreme droughts might be constrained by their growth prior to drought, and that more frequent and longer drought periods may overstrain their potential for acclimation.Marie SkĆodowska-Curie Individual Fellowship (PROJECT ID: 749051-REFOREST), Postdoctoral grant (IJCI-2015-25845,
FEDER funds), RTI2018-096884-B-C31, RTI2018-096884-B-C33 projects (Ministry of Ministry of Science, Innovation and Universities, Spain), VULBOS project (UPO-1263216, FEDER Funds, Andalusia Regional Government, ConsejerĂa de
EconomĂa, Conocimiento, Empresas y Universidad 2014-2020), PinCaR project (UHU-1266324, FEDER Funds, Andalusia Regional Government, ConsejerĂa de EconomĂa, Conocimiento, Empresas y Universidad 2014-2020), Bavarian Ministry of Science, Bavarian Climate Research Network (bayklif). project DENDROKLIMA by the German Waldklimafond (FKZ 28W-C-4-077-01), ST327 Bavarian State Ministry for Food, Agriculture, and Forestry. Landesforst MecklenburgVorpommern, Landeskompetenzzentrum Forst Eberswalde and Nordwestdeutsche Forstliche Versuchsanstalt
Complex regeneration responses of eight tree species to partial harvest in mixedwood forests of northeastern North America
Ecosystem-based forest management associated with partial harvesting (PH) is intended to balance ecological
and economic values of sustainable forest management. The potential for delayed growth response and elevated
mortality of advance regeneration following PH remains a critical concern, and may present a barrier to more
widespread implementation of this approach. We used 835 permanent continuous forest inventory plots to
examine the rate and time course of species-specific regeneration growth and mortality of eight tree species in
the first fifteen years following operational partial harvests in the mixed-species forests of Maine, United States.
We aimed to provide a quantitative understanding on how regeneration of different species responded to PH in
terms of growth and mortality. In addition, we evaluated how the patterns and magnitudes of growth and
mortality responses developed over time, if these responses occur gradually or suddenly, and if the patterns of the
responses were persistent. We found that the response magnitude, temporal trajectories of responses, and the
length of initial lag-period largely varied across species, PH treatments, and the variables examined. For sapling
diameter growth, paper birch (Betula papyrifera Marshall) and red maple (Acer rubrum L.) showed immediate
responses to high-intensity PH, while a five-year lag-period was observed in balsam fir (Abies balsamea (L.) Mill.),
American beech (Fagus grandifolia Ehrh.), red spruce (Picea rubens Sarg.) and eastern hemlock (Tsuga canadensis
(L.) Carri`ere) and a 10-year lag period in northern white-cedar (Thuja occidentalis L.). The initial increase in
sapling mortality was observed in balsam fir, American beech, red maple and northern white-cedar, but not in
other species. Sapling survival reached a stable state irrespective of species after the initial five-years following
harvests. In partially harvested stands, identifying preharvest conditions related to postharvest density, growth,
and mortality was complex and interacted with time since harvest. Our results suggest that broad application of
PH only results in species-specific gains, losses, and delays in regeneration responses within mixed-species
stands. Future research should consider PH in combination with other treatments to initiate immediate responses
to a wider range of species.We thank to US Forest Service Forest Inventory and Analysis (FIA)
for access to the long-term database. Funding was provided by the
United States National ScienceFoundationâs Center for Advanced
Forestry Systems (#1915078) and R-II Track-2 FEC (#1920908) and
from NSRC Alliance (ALLRP 557166 - 20)
Probabilistic Quantum Teleportation
We consider a generalized quantum teleportation protocol for an unknown qubit
using non-maximally entangled state as a shared resource. Without recourse to
local filtering or entanglement concentration, using standard Bell-state
measurement and classical communication one cannot teleport the state with unit
fidelity and unit probability. We show that using non-maximally entangled
measurements one can teleport an unknown state with unit fidelity albeit with
reduced probability, hence probabilistic teleportation. We also give a
generalized protocol for entanglement swapping using non-maximally entangled
states.Comment: Latex file, 11 pages, No figure
Growth and resilience responses of Scots pine to extreme droughts across Europe depend on predrought growth conditions
Global climate change is expected to further raise the frequency and severity of extreme events, such as droughts. The effects of extreme droughts on trees are difficult to disentangle given the inherent complexity of drought events (frequency, severity, duration, and timing during the growing season). Besides, drought effects might be modulated by treesâ phenotypic variability, which is, in turn, affected by long-term local selective pressures and management legacies. Here we investigated the magnitude and the temporal changes of tree-level resilience (i.e., resistance, recovery, and resilience) to extreme droughts. Moreover, we assessed the tree-, site-, and drought-related factors and their interactions driving the tree-level resilience to extreme droughts. We used a tree-ring network of the widely distributed Scots pine (Pinus sylvestris) along a 2,800 km latitudinal gradient from southern Spain to northern Germany. We found that the resilience to extreme drought decreased in mid-elevation and low productivity sites from 1980â1999 to 2000â2011 likely due to more frequent and severe droughts in the later period. Our study showed that the impact of drought on tree-level resilience was not dependent on its latitudinal location, but rather on the type of sites trees were growing at and on their growth performances (i.e., magnitude and variability of growth) during the predrought period. We found significant interactive effects between drought duration and tree growth prior to drought, suggesting that Scots pine trees with higher magnitude and variability of growth in the long term are more vulnerable to long and severe droughts. Moreover, our results indicate that Scots pine trees that experienced more frequent droughts over the long-term were less resistant to extreme droughts. We, therefore, conclude that the physiological resilience to extreme droughts might be constrained by their growth prior to drought, and that more frequent and longer drought periods may overstrain their potential for acclimation.Fondo Europeo de Desarrollo Regional (FEDER) IJCI-2015-25845, UPO-1263216, UHU-1266324Ministerio de Ciencia, InnovaciĂłn y Universidades RTI2018- 096884-B-C31, RTI2018-096884-B-C33German Waldklimafond FKZ 28WC-4-077-01Bavarian State Ministry for Food, Agriculture, and Forestry ST32
Quantum cobwebs: Universal entangling of quantum states
Entangling an unknown qubit with one type of reference state is generally
impossible. However, entangling an unknown qubit with two types of reference
states is possible. To achieve this, we introduce a new class of states called
zero sum amplitude (ZSA) multipartite, pure entangled states for qubits and
study their salient features. Using shared-ZSA state, local operation and
classical communication we give a protocol for creating multipartite entangled
states of an unknown quantum state with two types of reference states at remote
places. This provides a way of encoding an unknown pure qubit state into a
multiqubit entangled state. We quantify the amount of classical and quantum
resources required to create universal entangled states. This is possibly a
strongest form of quantum bit hiding with multiparties.Comment: Invited talk in II Winter Institute on FQTQO: Quantum Information
Processing, held at S. N. Bose Center for Basic Science, Kolkata, during Jan
2-11, 2002. (To appear in Pramana-J. of Physics, 2002.
One Century of Forest Monitoring Data in Switzerland Reveals Species- and Site-Specific Trends of Climate-Induced Tree Mortality
Climate-induced tree mortality became a global phenomenon during the last century and it is expected to increase in many regions in the future along with a further increase in the frequency of drought and heat events. However, tree mortality at the ecosystem level remains challenging to quantify since long-term, tree-individual, reliable observations are scarce. Here, we present a unique data set of monitoring records from 276 permanent plots located in 95 forest stands across Switzerland, which include five major European tree species (Norway spruce, Scots pine, silver fir, European beech, and sessile and common oak) and cover a time span of over one century (1898â2013), with inventory periods of 5â10 years. The long-term average annual mortality rate of the investigated forest stands was 1.5%. In general, species-specific annual mortality rates did not consistently increase over the last decades, except for Scots pine forests at lower altitudes, which exhibited a clear increase of mortality since the 1960s. Temporal trends of tree mortality varied also depending on diameter at breast height (DBH), with large trees generally experiencing an increase in mortality, while mortality of small trees tended to decrease. Normalized mortality rates were remarkably similar between species and a modest, but a consistent and steady increasing trend was apparent throughout the study period. Mixed effects models revealed that gradually changing stand parameters (stand basal area and stand age) had the strongest impact on mortality rates, modulated by climate, which had increasing importance during the last decades. Hereby, recent climatic changes had highly variable effects on tree mortality rates, depending on the species in combination with abiotic and biotic stand and site conditions. This suggests that forest species composition and species ranges may change under future climate conditions. Our data set highlights the complexity of forest dynamical processes such as long-term, gradual changes of forest structure, demography and species composition, which together with climate determine mortality rates
One Century of Forest Monitoring Data in Switzerland Reveals Species- and Site-Specific Trends of Climate-Induced Tree Mortality
Climate-induced tree mortality became a global phenomenon during the last century and it is expected to increase in many regions in the future along with a further increase in the frequency of drought and heat events. However, tree mortality at the ecosystem level remains challenging to quantify since long-term, tree-individual, reliable observations are scarce. Here, we present a unique data set of monitoring records from 276 permanent plots located in 95 forest stands across Switzerland, which include five major European tree species (Norway spruce, Scots pine, silver fir, European beech, and sessile and common oak) and cover a time span of over one century (1898â2013), with inventory periods of 5â10 years. The long-term average annual mortality rate of the investigated forest stands was 1.5%. In general, species-specific annual mortality rates did not consistently increase over the last decades, except for Scots pine forests at lower altitudes, which exhibited a clear increase of mortality since the 1960s. Temporal trends of tree mortality varied also depending on diameter at breast height (DBH), with large trees generally experiencing an increase in mortality, while mortality of small trees tended to decrease. Normalized mortality rates were remarkably similar between species and a modest, but a consistent and steady increasing trend was apparent throughout the study period. Mixed effects models revealed that gradually changing stand parameters (stand basal area and stand age) had the strongest impact on mortality rates, modulated by climate, which had increasing importance during the last decades. Hereby, recent climatic changes had highly variable effects on tree mortality rates, depending on the species in combination with abiotic and biotic stand and site conditions. This suggests that forest species composition and species ranges may change under future climate conditions. Our data set highlights the complexity of forest dynamical processes such as long-term, gradual changes of forest structure, demography and species composition, which together with climate determine mortality rates
Determinants of legacy effects in pine trees - implications from an irrigation-stop experiment
Tree responses to altered water availability range from immediate (e.g. stomatal regulation) to delayed (e.g. crown size adjustment). The interplay of the different response times and processes, and their effects on long-term whole-tree performance, however, is hardly understood. Here we investigated legacy effects on structures and functions of mature Scots pine in a dry inner-Alpine Swiss valley after stopping an 11-yr lasting irrigation treatment. Measured ecophysiological time series were analysed and interpreted with a system-analytic tree model. We found that the irrigation stop led to a cascade of downregulations of physiological and morphological processes with different response times. Biophysical processes responded within days, whereas needle and shoot lengths, crown transparency, and radial stem growth reached control levels after up to 4 yr only. Modelling suggested that organ and carbon reserve turnover rates play a key role for a tree's responsiveness to environmental changes. Needle turnover rate was found to be most important to accurately model stem growth dynamics. We conclude that leaf area and its adjustment time to new conditions is the main determinant for radial stem growth of pine trees as the transpiring area needs to be supported by a proportional amount of sapwood, despite the growth-inhibiting environmental conditions.Peer reviewe
Sensitivity Studies for Third-Generation Gravitational Wave Observatories
Advanced gravitational wave detectors, currently under construction, are
expected to directly observe gravitational wave signals of astrophysical
origin. The Einstein Telescope, a third-generation gravitational wave detector,
has been proposed in order to fully open up the emerging field of gravitational
wave astronomy. In this article we describe sensitivity models for the Einstein
Telescope and investigate potential limits imposed by fundamental noise
sources. A special focus is set on evaluating the frequency band below 10Hz
where a complex mixture of seismic, gravity gradient, suspension thermal and
radiation pressure noise dominates. We develop the most accurate sensitivity
model, referred to as ET-D, for a third-generation detector so far, including
the most relevant fundamental noise contributions.Comment: 13 pages, 7 picture
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