Water Transport In Trees Research Articles

What do we know about the needle xylem structure of the genus Pinus?

Summary Studies of needle xylem structure (NXS) are of importance in understanding the survival, and functioning of conifers, particularly in response to environmental stressors. Herein, I review the current state-of-the-art about the NXS of genus Pinus, focusing on the xylem, tracheid, and pit structure. Genus Pinus is one of the most important and widely distributed genera of forest trees in the Northern Hemisphere. Pine species are adapted to different soil types and extreme environments imposed by elevation and latitude. They grow successfully in the boreal forest, the Mediterranean Basin, and in mountains. The importance of NXS for long-distance water transport in trees is discussed and the relationships between xylem structure and function are highlighted. Little is known about the NXS of pines, as such information was available only for 12 pine species. Moreover, current knowledge about the NXS of pines is mostly based on Pinus sylvestris L., especially regarding the effect of environmental conditions on NXS. So far, tracheid pit structure has been investigated in only one study. Although NXS is also significantly influenced by tree age, the position of needles within the crown, as well as the location of the cross-section along the longitudinal axis of the needle, a detailed needle sampling design is often missing. Hence, it is suggested to extend future studies to other pine species to explain their resistance to drought and cold. Additionally, increasing the number of studies on adult trees and distinguishing between the different types of environmental stress that a tree can face during its life cycle would be beneficial. I strongly appeal to precise description of needle sampling, which will allow us both intraspecific and interspecific comparisons. Increasing knowledge about the NXS of pines will help to better explain their resistance to environmental stress and predict their tolerance to future climate change.

Near-Frictionless Long-Distance Water Transport in Trees Enabled by Hierarchically Helical Molecular Pumps

Near-Frictionless Long-Distance Water Transport in Trees Enabled by Hierarchically Helical Molecular Pumps

"One-Pot" Method Preparation of Dendritic Mesoporous Silica-Loaded Matrine Nanopesticide for Noninvasive Administration Control of Monochamus alternatus: The Vector Insect of Bursapherenchus xylophophilus.

Monochamus alternatus is an important stem-boring pest in forestry. However, the complex living environment of Monochamus alternatus creates a natural barrier to chemical control, resulting in a very limited control effect by traditional insecticidal pesticides. In this study, a stable pesticide dendritic mesoporous silica-loaded matrine nanopesticide (MAT@DMSNs) was designed by encapsulating the plant-derived pesticide matrine (MAT) in dendritic mesoporous silica nanoparticles (DMSNs). The results showed that MAT@DMSNs, sustainable nanobiopesticides with high drug loading capacity (80%) were successfully constructed. The release efficiency of DMSNs at alkaline pH was slightly higher than that at acidic pH, and the cumulative release rate of MAT was about 60% within 25 days. In addition, the study on the toxicity mechanism of MAT@DMSNs showed MAT@DMSNs were more effective than MAT and MAT (0.3% aqueous solutions) in touch and stomach toxicity, which might be closely related to their good dispersibility and permeability. Furthermore, MAT@DMSNs are also involved in water transport in trees, which can further transport the plant-derived insecticides to the target site and improve its insecticidal effect. Meanwhile, in addition, the use of essential oil bark penetrants in combination with MAT@DMSNs effectively avoids the physical damage to pines caused by traditional trunk injections and the development of new pests and diseases induced by the traditional trunk injection method, which provides a new idea for the application of biopesticides in the control of stem-boring pests in forestry.

A double cross-linked anisotropic quaternized chitosan/sodium alginate-based wound dressing for rapid drainage of biofluids

Excessive biofluid around wounds can cause infection and prevent healing. In this study, an anisotropic quaternized chitosan (QC)/sodium alginate (AL)-based aerogel wound dressing was prepared via a directional freeze-drying technique inspired by the channel structure used for water transport in trees. The aligned channels provided the dressing with self-pumping ability, allowing it to rapidly and completely remove biofluids and absorb biofluids up to 1292.5 % of its own weight. To enhance the strength of the dressing, a double cross-linked network was constructed based on the QC-AL electrostatic attraction and AL-Ca2+ chelation interaction. The axial compressive strength of the double cross-linked dressing reached 207.3 kPa (ε = 50 %). In addition, the dressing exhibited strong conductive properties (conductivity = 13.0 S/m), antioxidant activities [reactive oxygen species (ROS) scavenging ability = 88.0 %], and hemostatic characteristics (blood coagulation index = 1.8 %). The dressing also exhibited powerful antibacterial performance, exhibiting over 98.0 % inhibition of E. coli and S. aureus. Experiments on diabetic mouse models revealed that the dressing considerably promoted wound healing. On day 3, the wound healing rate was 96.7 % faster in the QAC group than in the gauze group. Therefore, the developed dressing may have great potential for chronic wound care.

Tree water transport dynamics in a changing climate

Tree water transport dynamics in a changing climate

Water Storage and Use by Platycladus orientalis under Different Rainfall Conditions in the Rocky Mountainous Area of Northern China

Tree water transport and utilization are essential for maintaining ecosystem stability in seasonally arid areas. However, it is not clear how Platycladus orientalis absorbs, consumes via transpiration, and stores water under varying precipitation conditions. Therefore, this study used stem sap flow thermal dissipation probes and hydrogen and oxygen isotope tracing technology to observe different water control treatments in a P. orientalis plantation. We found that the average daily sap flow of P. orientalis under different water control treatments had the following order: no rainfall (NR) < half rainfall (HR) < double rainfall (DR) < natural rainfall (AR). The percentage of nocturnal sap flow was as follows: AR (13.34%) < NR (19.62%) < DR (20.84%) < HR (30.90%). The percentage of water storage was NR (4.13%) < AR (4.49%) < DR (6.75%) < HR (9.29%). The sap flow of P. orientalis was primarily affected by vapor pressure deficit and solar radiation, with a degree of influence of DR < NR < HR < AR. The response of P. orientalis sap flow to environmental factors differed due to the soil changes in relative extractable water (REW) before and after precipitation. During high REW conditions, environmental factors have a higher impact on sap flow. The source of water absorbed changed regularly with the precipitation gradient. When soil water content increased, the water source used by P. orientalis gradually changed to shallow soil. Compared to before and after precipitation, there was no significant change except for NR. P. orientalis could regularly adjust the activities of transpiration water consumption, water storage, and absorption. This adaptive property is conducive to survival through extreme drought stress.

Phloem water isotopically different to xylem water: Potential causes and implications for ecohydrological tracing

AbstractThe stable isotopes of hydrogen and oxygen in xylem water are often used to investigate tree water sources. But this traditional approach does not acknowledge the contribution of water stored in the phloem to transpiration and how this may affect xylem water and source water interpretations. Additionally, there is a prevailing assumption that there is no isotope fractionation during tree water transport. Here, we systematically sampled xylem and phloem water at daily and subdaily resolutions in a large lysimeter planted with Salix viminalis. Stem diurnal change in phloem water storage and transpiration rates were also measured. Our results show that phloem water is significantly less enriched in heavy isotopes than xylem water. At subdaily resolution, we observed a larger isotopic difference between xylem and phloem during phloem water refilling and under periods of tree water deficit. These findings contrast with the expectation of heavy‐isotope enriched water in phloem due to downward transport of enriched leaf water isotopic signatures. Because of previous evidence of aquaporin mediated phloem and xylem water transport and higher osmotic permeability of lighter hydrogen isotopologues across aquaporins, we propose that radial water transport across the xylem–phloem boundary may drive the relative depletion of heavy isotopes in phloem and their relative enrichment in xylem.

Trees classification based on Fourier coefficients of the sapflow density flux

In this paper we study the possibility to use the artificial neural networks for trees classification based on real and approximated values of the sap flow density flux describing water transport in trees. The data sets were generated by means of a new tree monitoring system TreeTalker. The Fourier series-based model is used for fitting the data sets with periodic patterns. The multivariate regression model defines the functional dependencies between sap flow density and temperature time series. The paper shows that Fourier coefficients can be successfully used as elements of the feature vectors required to solve different classification problems. Here we train multilayer neural networks to classify the trees according to different types of classes. The quality of the developed model for prediction and classification is verified by numerous numerical examples.

Influence of soil warming and N‐addition on sap flux density and stem radius variation in boreal stands in Quebec, Canada

AbstractClimate change is projected to intensify the global hydrological cycle and increase temperatures. Excess N deposition could limit plant productivity because of a lack of plant–soil system efficiency with reduced water availability. However, the effects of soil warming and N‐addition on tree water transport and water use remain poorly understood. This study aimed to quantify the effects of soil warming and N‐addition associated with meteorological variables on the sap flux density and stem radius variation in black spruce (Picea mariana [Mill.] B.S.P.). From 2008 to 2014, we conducted a long‐term experiment on mature trees growing in two stands (Bernatchez [BER] and Simoncouche [SIM]) at different latitudes to evaluate the effect of soil warming (H) and N‐addition. During 2014, we investigated soil and plant water status between May and August, sap flux density from July to August and stem radius variation over the whole year. At the colder, northern site (BER), we detected a significant increase in sap flux density with the H‐treatment, whereas no effect was observed at the warmer, southern site (SIM). At BER, diurnal sap flux density in H × N‐addition treatment showed a significant effect in the afternoon near the peak of day compared with the other treatments. We found no significant effects of independent single or combined factors on soil and plant water status and stem radius variation at either site. Under climate change, black spruce at more northern sites could have a better water use and storage for wood productivity than those at more southern sites.

Is Decreased Xylem Sap Surface Tension Associated With Embolism and Loss of Xylem Hydraulic Conductivity in Pathogen-Infected Norway Spruce Saplings?

Increased abiotic stress along with increasing temperatures, dry periods and forest disturbances may favor biotic stressors such as simultaneous invasion of bark beetle and ophiostomatoid fungi. It is not fully understood how tree desiccation is associated with colonization of sapwood by fungi. A decrease in xylem sap surface tension (σxylem) as a result of infection has been hypothesized to cause xylem embolism by lowering the threshold for air-seeding at the pits between conduits and disruptions in tree water transport. However, this hypothesis has not yet been tested. We investigated tree water relations by measuring the stem xylem hydraulic conductivity (Kstem), σxylem, stem relative water content (RWCstem), and water potential (Ψstem), and canopy conductance (gcanopy), as well as the compound composition in xylem sap in Norway spruce (Picea abies) saplings. We conducted our measurements at the later stage of Endoconidiophora polonica infection when visible symptoms had occurred in xylem. Saplings of two clones (44 trees altogether) were allocated to treatments of inoculated, wounded control and intact control trees in a greenhouse. The saplings were destructively sampled every second week during summer 2016. σxylem, Kstem and RWCstem decreased following the inoculation, which may indicate that decreased σxylem resulted in increased embolism. gcanopy did not differ between treatments indicating that stomata responded to Ψstem rather than to embolism formation. Concentrations of quinic acid, myo-inositol, sucrose and alkylphenol increased in the xylem sap of inoculated trees. Myo-inositol concentrations also correlated negatively with σxylem and Kstem. Our study is a preliminary investigation of the role of σxylem in E. polonica infected trees based on previous hypotheses. The results suggest that E. polonica infection can lead to a simultaneous decrease in xylem sap surface tension and a decline in tree hydraulic conductivity, thus hampering tree water transport.

Temporal Characteristics of P-Band Tomographic Radar Backscatter of a Boreal Forest

Temporal variations in synthetic aperture radar (SAR) backscatter over forests are of concern for any SAR mission with the goal of estimating forest parameters from SAR data. In this article, a densely sampled, two-year long time series of P-band (420 to 450 MHz) boreal forest backscatter, acquired by a tower-based radar, is analyzed. The experiment setup provides time series data at multiple polarizations. Tomographic capabilities allow the separation of backscatter at different heights within the forest. Temporal variations of these multipolarized, tomographic radar observations are characterized and quantified. The mechanisms studied are seasonal variations, effects of freezing conditions, diurnal variations, effects of wind, and the effects of rainfall on backscatter. An emphasis is placed on upper-canopy backscatter, which has been shown to be a robust proxy for forest biomass. The canopy backscatter was more stable than ground-level backscatter during nonfrozen conditions, supporting forest parameter retrieval approaches based on tomography or interferometric ground notching. Large backscatter variations during frozen conditions, which may be detected using cross-polarized backscatter observations, can result in large errors in forest parameter estimates. Diurnal backscatter variations observed during hot periods were likely connected to tree water transport and storage mechanisms. Backscatter changes were also observed during strong winds. These variations were small in comparison to the variations due to freeze-thaw and soil moisture changes and should not result in significant forest parameter estimation errors. The presented results are useful for designing physically based and semiempirical scattering models that account for temporal changes in scattering characteristics.

Tree water transport mediating the changing environmental conditions to tree physiological processes

Tree water transport mediating the changing environmental conditions to tree physiological processes

The impact of rising CO2 and acclimation on the response of US forests to global warming

The response of forests to climate change depends in part on whether the photosynthetic benefit from increased atmospheric CO2 (∆Ca = future minus historic CO2) compensates for increased physiological stresses from higher temperature (∆T). We predicted the outcome of these competing responses by using optimization theory and a mechanistic model of tree water transport and photosynthesis. We simulated current and future productivity, stress, and mortality in mature monospecific stands with soil, species, and climate sampled from 20 continental US locations. We modeled stands with and without acclimation to ∆Ca and ∆T, where acclimated forests adjusted leaf area, photosynthetic capacity, and stand density to maximize productivity while avoiding stress. Without acclimation, the ∆Ca-driven boost in net primary productivity (NPP) was compromised by ∆T-driven stress and mortality associated with vascular failure. With acclimation, the ∆Ca-driven boost in NPP and stand biomass (C storage) was accentuated for cooler futures but negated for warmer futures by a ∆T-driven reduction in NPP and biomass. Thus, hotter futures reduced forest biomass through either mortality or acclimation. Forest outcomes depended on whether projected climatic ∆Ca/∆T ratios were above or below physiological thresholds that neutralized the negative impacts of warming. Critically, if forests do not acclimate, the ∆Ca/∆T must be above ca 89 ppm⋅°C-1 to avoid chronic stress, a threshold met by 55% of climate projections. If forests do acclimate, the ∆Ca/∆T must rise above ca 67 ppm⋅°C-1 for NPP and biomass to increase, a lower threshold met by 71% of projections.

Frost fatigue and its spring recovery of xylem conduits in ring-porous, diffuse-porous, and coniferous species in situ

Frost-induced embolism and frost fatigue are two major aspects of frost damage to xylem water transport in trees. In this study, three species of each ring-porous, diffuse-porous, and coniferous trees growing in situ were used to explore their differences in winter embolism and frost fatigue. Changes in predawn water potential, predawn native embolism, maximal specific conductivity (Kmax), and cavitation resistance (P50, xylem water potential at 50% loss of conductivity) of current-year branches were measured from autumn to spring. Maximum native embolism of late winter was near 100% for ring-porous species, approximately 80% for diffuse-porous species, and below 50% for conifers. In early spring, there was no significant reduction of native embolism until formation of new vessels in ring-porous trees, while diffuse-porous trees and conifers exhibited a reduction in native embolism before development of new xylem. There was a significant decrease in P50 of ring- and diffuse-porous species over winter; however, in May P50 was markedly reduced along with formation of new vessels. Kmax of ring- and diffuse-porous species significantly decreased from autumn to late winter. The results revealed that vulnerability to cavitation and frost fatigue was related to conduit diameter. The strategies for coping with winter embolism differed among the three wood types: in ring-porous species there was no active embolism refilling; in diffuse-porous species there was refilling associated with positive xylem pressure; and in conifers there was refilling without positive xylem pressure. New vessels could completely restore stem hydraulic conductivity but only partially restore xylem cavitation resistance in spring.

New tree monitoring systems: from Industry 4.0 to Nature 4.0

Recently, Internet of Things (IoT) technologies have grown rapidly and represent now a unique opportunity to improve our environmental monitoring capabilities at extremely low costs. IoT is a new system of thinking in which objects, animals or people are equipped with unique identifiers and transfer data a network without requiring human-to-human or human-to-computer interaction. IoT has evolved from the convergence of wireless technologies, microelectromechanical systems (MEMS) and the Internet. The development of these technologies in environmental monitoring domains allows real-time data transmission and numerous low-cost monitoring points. We have designed a new device, the TreeTalker©, which is capable of measuring water transport in trees, diametrical growth, spectral characteristics of the leaves and microclimatic parameters and transmit data in semi-real time. Here we introduce the device’s features, provide an example of monitored data from a field test site and discuss the application of this new technology to tree monitoring in various contexts, from forest to urban green infrastructures management and ecological research.

Close to the edge: effects of repeated severe drought on stem hydraulics and non-structural carbohydrates in European beech saplings.

Severe drought events threaten tree water transport system, productivity and survival. Woody angiosperms generally die when embolism-induced loss of hydraulic conductance (PLC) surpasses 80-90% under intense water shortage. However, the recovery capability and possible long-term carry-over effects of repeated drought events could dictate the fate of species' population under climate change scenarios. Potted saplings of European beech (Fagus sylvatica L.) were subjected to two drought cycles in two consecutive growing seasons, aiming to induce minimum leaf water potentials (Ψmd) of about -4 MPa, corresponding to hydraulic thresholds for survival of this species. In the first cycle, a well-irrigated (C) and a drought-stressed group (S) were formed, and, in the following summer, each group was divided in a well-irrigated and a drought-stressed one (four groups in total). The impact of the multiple drought events was assessed by measuring wood anatomical traits, biomass production, water relations, stem hydraulics and non-structural carbohydrate (NSC) content. We also investigated possible connections between stem hydraulics and carbon dynamics during the second drought event and following re-irrigation. S plants had lower Ψmd and maximum specific hydraulic conductivity (Ks) than C plants in the following growing season. Additionally, aboveground biomass production and leaf number were lower compared to C trees, resulting in lower water consumption. However, PLC was similar between groups, probably due to the production of new functional xylem in spring. The second drought event induced 85% PLC and promoted conversion of starch-to soluble sugars. Nevertheless, 1 week after re-irrigation, no embolism repair was observed and soluble sugars were reconverted to starch. The previous drought cycle did not influence the hydraulic performance during the second drought, and after re-irrigation S plants had 40% higher wood NSC content. Our data suggest that beech cannot recover from high embolism levels but multiple droughts might enhance stem NSC availability.

Hydraulic Anatomy and Function of Trees—Basics and Critical Developments

The study of hydraulic anatomy and function of trees has a long tradition. Motivated by current and projected changes in water availability, the field of tree hydraulics is experiencing a bout of activity. Significant progress has been made in understanding how water transport in trees is organized, how it integrates with other physiological processes, and what it takes for it to malfunction. Many of these advances have been possible, as fields of research that have traditionally been separate are merging, for example, wood anatomy and plant ecophysiology. These developments have led to the creation of powerful and novel approaches that help to answer longstanding questions relating to fundamental aspects of fluid transport in plants and how plants survive in the face of environmental stresses such as drought and freezing. The increased capacities to visualize the ultrastructures of wood in ever-greater detail and the ability for in-situ visualization of long-distance fluid transport have contributed to this progress. This review provides an entry point to the vast and continuously increasing knowledge of how water transport in trees is organized. It scales from cells to tissue anatomy to whole-tree physiology and landscape ecology. Known mechanisms and novel conceptual theories around how trees die as well as ways to prevent this fate are summarized. High-priority research questions for the coming years are formulated.

Rapid tree water transport and residence times in a Pennsylvania catchment

AbstractTrees are responsible for the majority of precipitation recycling over land and can affect soil water storage, stream flow, and ground water recharge. Historically, water has not often been limiting in eastern U.S. forests. As a result, little work has been done to understand the timing of water use by vegetation in these systems. We used deuterium tracer, sap flux, and anatomical techniques to study tree water transport on a forested ridge top in central Pennsylvania. Three trees of each of the dominant ring‐porous species, Carya tomentosa (mockernut hickory), Quercus prinus (chestnut oak), and Quercus rubra (red oak), and the diffuse‐porous Acer saccharum (sugar maple), were studied. We hypothesized that tracer velocity would be higher in the ring‐porous species because of their greater vessel diameters and water transport efficiency, but that tracer residence time would be largely dependent on tree size. The tracer travelled at velocities of 1 to 18 m d−1 with maximum deuterium concentration in the crowns of the study trees being reached between 1 and 12 days after injection. Tracer residence time ranged from about 5 to 22 days with no evidence of longer residence times in larger trees. There was also no evidence of a relationship between tracer velocity and calculated xylem specific conductivity, which varied by nearly an order of magnitude between species. However, the soil‐to‐leaf driving force for water transport may be a strong determinant of tracer velocity across species, and shows promise as a proxy for sap velocity in hydrologic modelling applications. Copyright © 2016 John Wiley & Sons, Ltd.

UNTERSUCHUNGEN ÜBER DIE GESCHWINDIGKEIT DES WASSERAUFSTIEGES IM SPROFI UND DEN BLATTFLÁCHENZUWACHS VON COFFEA ARABICA L. UND CITRUS AURANTIUM SINENSIS ENGLER IN VERSCHIEDENEN KLIMAZONEN KOLUMBIENS

The total increase of leaf area and the rate of water movement in the stems of Coffea arabica L. and Citrus aurantium sinensis Engler were deter- *) Gekürzte Fassung einer am 18. 12. 1969 von der Naturwissenschaftlichen Fakultat der Universitát Giessen als Dissertation angenommenen Abhandlung. mined in various climatic regions of Columbia. During the rain season the maximum rate of water transport decreased with increasing height above sea level. This effect was observed to be more evident in Citrus than in Coffea. At the end of the dry season however, the maximum rate of water movement was measured in 1250 m (Citrus) and 1850 m (Coffea) above sea level. In case of sunshine the maximum values were higher than in case of clouded sky. The most considerable increase of total leaf area was reached at Coffea in 1850 m and at Citrus in 1250 m respectively. With reference to the water economy the cultivation of Citrus could be forced in sea levels about 1250 m with simultaneous displacement of Coffea cultivation to colder climatic regions. Diurnal variations showed, that if the intensity of radiation increased suddenly, the rate of water movement in the stems of Citrus trees accordingly increased. With Coffea trees different results were obtained. During the morning the rate of water transport in trees always increased. At noon the values either remained high or varied in irregular intervals. Moreover, in the hot climatic regions diurnal variations sometimes showed two maximums of rate of water flow in the stems of Coffea arabica. Above all, the type of observed diurnal variations depended on the sea level distance of the measuring point, the season, the intensity of radiation and the species of plant.

Trees in a changing environment: ecophysiology, adaptation, and future survival

Preface M. Tausz, N.E. Grulke 1. Ecophysiology of resource allocation and trade-offs in carbon gain under changing environment K Hikosaka, Y Yasumura, O Muller, R Oguchi 2. Ecophysiological aspects of phloem transport in trees T. Holtta, M. Mencuccini, E. Nikinmaa 3. Mycorrhizae and global change M.F. Allen, K. Kitajima, R.R. Hernandez 4. Dynamic stomatal changes H. Kaiser, E. Paoletti 5. The regulation of osmotic potential in trees A. Merchant 6. Ecophysiology of long-distance water transport in trees H. Richter, S. Kikuta 7. Forest trees under air pollution as a factor of climate change R. Matyssek, A.R. Kozovits, J.-P. Schnitzler, H. Pretzsch, J. Dieler, G. Wieser 8. Influence of atmospheric and climate change on tree defence chemicals J.Q.D. Goodger, I.E. Woodrow 9. Control over growth in cold climates S. Rossi, A. Deslauriers, C. Lupi, H. Morin 10. Treelines in a changing global environment G. Wieser, F.-K. Holtmeier, W.K. Smith 11. The future of trees in a changing climate - synopsis N.E. Grulke, M. Tausz.