scholarly journals Rapid hydraulic collapse as cause of drought-induced mortality in conifers

2021 ◽  
Vol 118 (16) ◽  
pp. e2025251118
Author(s):  
Matthias Arend ◽  
Roman M. Link ◽  
Rachel Patthey ◽  
Günter Hoch ◽  
Bernhard Schuldt ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Water Relations ◽  
Hydraulic System ◽  
Temporal Dynamics ◽  
Severe Drought ◽  
Xylem Cavitation ◽  
Adult Trees ◽  
Hydraulic Safety ◽  
Underlying Mechanisms ◽  
Short Time

Understanding the vulnerability of trees to drought-induced mortality is key to predicting the fate of forests in a future climate with more frequent and intense droughts, although the underlying mechanisms are difficult to study in adult trees. Here, we explored the dynamic changes of water relations and limits of hydraulic function in dying adults of Norway spruce (Picea abies L.) during the progression of the record-breaking 2018 Central European drought. In trees on the trajectory to drought-induced mortality, we observed rapid, nonlinear declines of xylem pressure that commenced at the early onset of xylem cavitation and caused a complete loss of xylem hydraulic conductance within a very short time. We also observed severe depletions of nonstructural carbohydrates, though carbon starvation could be ruled out as the cause of the observed tree death, as both dying and surviving trees showed these metabolic limitations. Our observations provide striking field-based evidence for fast dehydration and hydraulic collapse as the cause of drought-induced mortality in adult Norway spruce. The nonlinear decline of tree water relations suggests that considering the temporal dynamics of dehydration is critical for predicting tree death. The collapse of the hydraulic system within a short time demonstrates that trees can rapidly be pushed out of the zone of hydraulic safety during the progression of a severe drought. In summary, our findings point toward a higher mortality risk for Norway spruce than previously assumed, which is in line with current reports of unprecedented levels of drought-induced mortality in this major European tree species.

scholarly journals Investigating the Spatio-Temporal Variation of Soil Moisture and Agricultural Drought towards Supporting Water Resources Management in the Red River Basin of Vietnam

2021 ◽  
Vol 13 (9) ◽  
pp. 4926
Author(s):  
Nguyen Duc Luong ◽  
Nguyen Hoang Hiep ◽  
Thi Hieu Bui
Keyword(s):  
Soil Moisture ◽  
River Basin ◽  
Temporal Dynamics ◽  
Regional Scale ◽  
Dry Season ◽  
Red River ◽  
Agricultural Drought ◽  
Severe Drought ◽  
Red River Basin ◽  
Spatio Temporal

The increasing serious droughts recently might have significant impacts on socioeconomic development in the Red River basin (RRB). This study applied the variable infiltration capacity (VIC) model to investigate spatio-temporal dynamics of soil moisture in the northeast, northwest, and Red River Delta (RRD) regions of the RRB part belongs to territory of Vietnam. The soil moisture dataset simulated for 10 years (2005–2014) was utilized to establish the soil moisture anomaly percentage index (SMAPI) for assessing intensity of agricultural drought. Soil moisture appeared to co-vary with precipitation, air temperature, evapotranspiration, and various features of land cover, topography, and soil type in three regions of the RRB. SMAPI analysis revealed that more areas in the northeast experienced severe droughts compared to those in other regions, especially in the dry season and transitional months. Meanwhile, the northwest mainly suffered from mild drought and a slightly wet condition during the dry season. Different from that, the RRD mainly had moderately to very wet conditions throughout the year. The areas of both agricultural and forested lands associated with severe drought in the dry season were larger than those in the wet season. Generally, VIC-based soil moisture approach offered a feasible solution for improving soil moisture and agricultural drought monitoring capabilities at the regional scale.

scholarly journals Mapping the Spatial-Temporal Dynamics of Vegetation Response Lag to Drought in a Semi-Arid Region

2019 ◽  
Vol 11 (16) ◽  
pp. 1873 ◽  
Author(s):  
Li Hua ◽  
Huidong Wang ◽  
Haigang Sui ◽  
Brian Wardlow ◽  
Michael J. Hayes ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Temporal Dynamics ◽  
Risk Mitigation ◽  
Scientific Information ◽  
Gaussian Function ◽  
Drought Risk ◽  
Severe Drought ◽  
Similar Response ◽  
Vegetation Types ◽  
Data Set

Drought, as an extreme climate event, affects the ecological environment for vegetation and agricultural production. Studies of the vegetative response to drought are paramount to providing scientific information for drought risk mitigation. In this paper, the spatial-temporal pattern of drought and the response lag of vegetation in Nebraska were analyzed from 2000 to 2015. Based on the long-term Daymet data set, the standard precipitation index (SPI) was computed to identify precipitation anomalies, and the Gaussian function was applied to obtain temperature anomalies. Vegetation anomaly was identified by dynamic time warping technique using a remote sensing Normalized Difference Vegetation Index (NDVI) time series. Finally, multilayer correlation analysis was applied to obtain the response lag of different vegetation types. The results show that Nebraska suffered severe drought events in 2002 and 2012. The response lag of vegetation to drought typically ranged from 30 to 45 days varying for different vegetation types and human activities (water use and management). Grasslands had the shortest response lag (~35 days), while forests had the longest lag period (~48 days). For specific crop types, the response lag of winter wheat varied among different regions of Nebraska (35–45 days), while soybeans, corn and alfalfa had similar response lag times of approximately 40 days.

scholarly journals Combined Effect of Altitude, Season and Light on the Accumulation of Extractable Terpenes in Norway Spruce Needles

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1737
Author(s):  
Kristýna Večeřová ◽  
Karel Klem ◽  
Barbora Veselá ◽  
Petr Holub ◽  
John Grace ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Interactive Effect ◽  
Total Content ◽  
Growth Conditions ◽  
Biotic And Abiotic Stresses ◽  
Adult Trees ◽  
Canopy Position ◽  
Germacrene D ◽  
Spruce Needles ◽  
Evergreen Conifers

Plants produce specific terpenes, secondary metabolites conferring tolerance to biotic and abiotic stresses. Our study aims to investigate the effects of altitude, light intensity and season on contents of mono- and sesquiterpenes in needles of coniferous Norway spruce (Picea abies). Needles of current shoots representing upper and lower canopy were collected from adult trees growing along an altitudinal gradient (400–1100 m a.s.l.) in summer and autumn. After the extraction in cold heptane, the content of extractable terpenes was determined by gas chromatography coupled with mass spectrometry. Our results show that the total content of terpenes decreases with increasing altitude regardless of canopy position and season. Needles of the upper canopy have a higher total content of terpenes than lower canopy needles, but this difference decreases with increasing altitude in summer. Total content of extractable terpenes increases in autumn when compared to summer particularly in upper canopy needles of trees from high altitudes. Limonene, camphene, α-pinene and myrcene are the most abundant monoterpenes in spruce needles forming up to 85% of total monoterpenes, while germacrene D-4-ol is the most abundant sesquiterpene. Altitude, canopy position and season have a significant interactive effect on most monoterpenes, but not on sesquiterpenes. Terpenoid biosynthesis is thus tightly linked to growth conditions and likely plays a crucial role in the constitution of stress tolerance in evergreen conifers.

scholarly journals An Inactivation Switch Enables Rhythms in a Neurospora Clock Model

2019 ◽  
Vol 20 (12) ◽  
pp. 2985 ◽  
Author(s):  
Abhishek Upadhyay ◽  
Michael Brunner ◽  
Hanspeter Herzel
Keyword(s):  
Feedback Loop ◽  
Design Principle ◽  
Temporal Dynamics ◽  
Model Organism ◽  
Transcription Activator ◽  
White Collar Complex ◽  
Living Organisms ◽  
Underlying Mechanisms ◽  
Molecular Components ◽  
Novel Model

Autonomous endogenous time-keeping is ubiquitous across many living organisms, known as the circadian clock when it has a period of about 24 h. Interestingly, the fundamental design principle with a network of interconnected negative and positive feedback loops is conserved through evolution, although the molecular components differ. Filamentous fungus Neurospora crassa is a well-established chrono-genetics model organism to investigate the underlying mechanisms. The core negative feedback loop of the clock of Neurospora is composed of the transcription activator White Collar Complex (WCC) (heterodimer of WC1 and WC2) and the inhibitory element called FFC complex, which is made of FRQ (Frequency protein), FRH (Frequency interacting RNA Helicase) and CK1a (Casein kinase 1a). While exploring their temporal dynamics, we investigate how limit cycle oscillations arise and how molecular switches support self-sustained rhythms. We develop a mathematical model of 10 variables with 26 parameters to understand the interactions and feedback among WC1 and FFC elements in nuclear and cytoplasmic compartments. We performed control and bifurcation analysis to show that our novel model produces robust oscillations with a wild-type period of 22.5 h. Our model reveals a switch between WC1-induced transcription and FFC-assisted inactivation of WC1. Using the new model, we also study the possible mechanisms of glucose compensation. A fairly simple model with just three nonlinearities helps to elucidate clock dynamics, revealing a mechanism of rhythms’ production. The model can further be utilized to study entrainment and temperature compensation.

Feedback Servo Pump Station Overflow Innovative Energy-Saving Design

2011 ◽  
Vol 341-342 ◽  
pp. 452-455
Author(s):  
Liang Yuan Shen ◽  
Hong Guang Wang ◽  
Rui Jun Zhang ◽  
Peng Peng Liu
Keyword(s):  
Energy Saving ◽  
Hydraulic System ◽  
Adaptive Functioning ◽  
Supply Voltage ◽  
Load Condition ◽  
Control Valve ◽  
Work Requirements ◽  
Pump Station ◽  
Short Time ◽  
Large Flow

The usual hydraulic pump station pumps the general use of quantitative supply voltage level or constant pressure, using the corresponding control valve speed to adapt to work requirements, when the hydraulic system is intermittent or low-load condition, a large number of high-pressure oil through regulator overflow Back to the tank overflow valve, causing a great deal of energy consumption, when the hydraulic system requires a large flow of oil, it will result in a short time for the fluid system for liquid inadequate and under-voltage phenomenon. To solve this problem, we propose to improve the program, and conducted the analysis and comparison of several options to determine the source of energy-saving adaptive overall scheme of oil, its reasonable design, implementation of the automatic adaptive functioning, energy loss Small, the effect is significant.

scholarly journals Direct detection of molecular intermediates from first-passage times

2020 ◽  
Vol 6 (18) ◽  
pp. eaaz4642 ◽  
Author(s):  
Alice L. Thorneywork ◽  
Jannes Gladrow ◽  
Yujia Qing ◽  
Marc Rico-Pasto ◽  
Felix Ritort ◽  
...  
Keyword(s):  
Direct Detection ◽  
First Passage Time ◽  
Passage Time ◽  
Energy Landscapes ◽  
First Passage ◽  
Dna Hairpins ◽  
Experimental Systems ◽  
Intermediate States ◽  
Underlying Mechanisms ◽  
Short Time

All natural phenomena are governed by energy landscapes. However, the direct measurement of this fundamental quantity remains challenging, particularly in complex systems involving intermediate states. Here, we uncover key details of the energy landscapes that underpin a range of experimental systems through quantitative analysis of first-passage time distributions. By combined study of colloidal dynamics in confinement, transport through a biological pore, and the folding kinetics of DNA hairpins, we demonstrate conclusively how a short-time, power-law regime of the first-passage time distribution reflects the number of intermediate states associated with each of these processes, despite their differing length scales, time scales, and interactions. We thereby establish a powerful method for investigating the underlying mechanisms of complex molecular processes.

The more, the better? Water relations of Norway spruce stands after progressive thinning

2014 ◽  
Vol 197 ◽  
pp. 235-243 ◽  
Author(s):  
Timo Gebhardt ◽  
Karl-Heinz Häberle ◽  
Rainer Matyssek ◽  
Christoph Schulz ◽  
Christian Ammer
Keyword(s):  
Norway Spruce ◽  
Water Relations ◽  
Spruce Stands

Exposure of mature Norway spruce to ozone in twig-chambers: effects on gas exchange

1994 ◽  
Vol 102 ◽  
pp. 119-125
Author(s):  
Gerhard Wieser ◽  
Wilhelm M. Havranek
Keyword(s):  
Gas Exchange ◽  
Picea Abies ◽  
Norway Spruce ◽  
Treatment Effects ◽  
Stomatal Closure ◽  
Ambient Conditions ◽  
Response Curves ◽  
Adult Trees

SynopsisLittle is known about ozone (O3) effects on adult trees in the field, where ecophysiological parameters control pollutant uptake. It was the goal of this study to examine how ambient and above ambient O3 concentrations affect gas exchange of mature Norway spruce (Picea abies (L.) Karst.). Therefore, twigs were enclosed in chambers and exposed to different O3 concentrations for one and two seasons over three years. During winter periods twigs were maintained under ambient conditions. Data from the shade crown of spruce trees at 1000 m a.s.l. are presented. After one and two fumigation periods no clear treatment effects on gas exchange were observed in twigs fumigated with O3 concentrations ranging from zero up to ambient (A) + 60 ppb. However, O3 at 90 ppb reduced photosynthesis and conductance. CO2 response curves indicated that in A + 90 twigs the efficiency of CO2 uptake was diminished. Observed losses in Pn of A + 90 twigs were greater than reductions in conductance indicating that stomatal closure alone did not limit CO2 uptake. We conclude that ambient and slightly above ambient O3 concentrations do not alter gas exchange of mature Norway spruce. Therefore, suppositions on O3 damage on mature spruce trees should be critically questioned.

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