Separating the effects of air and soil temperature on silver birch. Part I. Does soil temperature or resource competition determine the timing of root growth?

The aboveground parts of boreal forest trees mostly grow earlier, and the roots later, in the growing season. We aimed to experimentally test whether the extrinsic driver of soil temperature or the intrinsic driver (resource competition between plant parts) is a more important control for the root and shoot growth of silver birch (Betula pendula Roth) seedlings. Sixteen two-year-old seedlings were grown in controlled environment rooms for two simulated growing seasons (GS1, GS2). In GS1, all the seedlings were acclimatized under the same conditions, but in GS2, the soil temperature treatments were: (i) constant 10 °C (Cool); (ii) constant 18 °C (Warm); (iii) early growing season at 10 °C, switched to 18 °C later (Early Cool Late Warm, ECLW) and (iv) early growing season 18 °C, switched to 10 °C later (Early Warm Late Cool, EWLC). The treatments did not affect growth allocation between shoots and roots. Warm soil benefitted shoot elongation as it slowed down in EWLC and accelerated in ECLW after the soil temperature switch. However, whole-tree biomasses were similar to Cool and the seedlings grew largest in Warm. Phenology was not strongly affected by soil temperature, and root and shoot growth did not usually peak simultaneously. Short root mortality increased strongly in ECLW and decreased in EWLC after the soil temperature switch. Long root longevity was not significantly affected but long root growth ceased earliest in ECLW. Soil warming increased foliar nutrient contents. Growth dynamics were not solely driven by soil temperature, but resource competition also played a significant role. The study showed the importance of soil temperature for fine root dynamics not only through root growth but also via root mortality, as soil warming increased mortality even more than growth. Soil temperature has complex effects on tree and soil functioning, which further affects carbon dynamics in forest ecosystems that have a climate feedback.

Here comes the flood! Stress effects of continuous and interval waterlogging periods during the growing season on Scots pine saplings.

Future climate scenarios for the boreal zone project increasing temperatures and precipitation, as well as extreme weather events such as heavy rain during the growing season. This can result in more frequent short-term waterlogging (WL) leading to unfavorable conditions for tree roots. In addition, it is decisive whether short-term WL periods during the growing season occur continuously or periodically. We assessed the effects of short-termed WL on 4-year-old Scots pine (Pinus sylvestris L.) saplings after shoot elongation started. Waterlogging (WL) lasted either continuously for 2.5 weeks (ContWL) or noncontinuously for 5 weeks, consisting of three repeated 1-week-interval WL periods (IntWL). Both treatments resulted in the same duration of soil anoxia. We studied soil gases, root and shoot growth and physiology, and root survival probability and longevity during the experiment. In the final harvest, we determined shoot and root biomass and hydraulic conductance and electrical impedance spectra of the root systems. Soil CO2 and CH4 concentrations increased immediately after WL onset and O2 decreased until anoxia. Waterlogging decreased fine root survival probability, but there was no difference between WL treatments. Shoot growth suffered more from ContWL and root growth more from IntWL. Needle concentrations of pinitol increased in the WL saplings, indicating stress. No WL effects were observed in photosynthesis and chlorophyll fluorescence. Increased starch concentration in needles by WL may be due to damaged roots and thus a missing belowground sink. Electrical impedance indicated suffering of WL saplings, although root hydraulic conductance did not differ between the treatments. Oxidative stress of short-term and interval WL can have long-lasting effects on shoot and root growth and the physiology of Scots pine. We conclude that even short-term WL during the growing season is a stress factor, which will probably increase in the future and can affect carbon allocation and dynamics in boreal forests.

Optical evaluation of ink prints made with heat-treated alder and birch.

Japanese woodblock printmaking is a traditional printing method practiced for centuries. The modern challenge to this fine art is the constantly decreasing amount of available wood, wild cherry tree, which has been traditionally used as a printing block material. The increasing amount of interest focuses on finding alternative wood types, which would compare successfully with the desired quality of the wild cherry tree. Our initial research has shown that heat-treated alder and birch trees could both be considered as possible alternatives for block material. In this paper we introduce the optical characterization (CIELAB color and gloss) of black ink prints made on two different handmade papers with printing blocks made of low-temperature (120°C, 140°C) heat-treated alder and birch. Results show lowered ink transfer from wood when the heat treatment temperature rises, more transferred ink from alder, and printing paper differences due to fiber content differences.

Optical analysis of adsorption sensitivity of titanium, Ti-6Al-4V, and Ti-35Nb-6Ta.

Here we report the optical analysis of protein adsorption sensitivity of titanium (Ti), Ti(6)Al(4)V, and Ti(35)Nb(6)Ta. The optical sensor used was a diffractive optical element based sensor, which analyzes magnitude and coherence of probe beam reflected from the measured surfaces. Also, the roughness and other necessary parameters were taken into account on the final verdict. The material Ti(35)Nb(6)Ta showed positive initial reaction to the human plasma fibrinogen, which was the protein used. The Ti(35)Nb(6)Ta was observed to be more active than the grade 2 titanium.

Analysis of the willow root system by electrical impedance spectroscopy.

Information on plant roots is increasingly needed for understanding and managing plants under various environmental conditions, including climate change. Several methods have been developed to study fine roots but they are either destructive or cumbersome, or may not be suitable for studies of fine root functionality. Electrical impedance, resistance, and capacitance have been proposed as possible non-destructive measures for studying roots. Their use is limited by a lack of knowledge concerning the electrical circuit of the system. Electrical impedance spectroscopy (EIS) was used for hydroponically raised willows (Salix schwerinii) to estimate the root system size. The impedance spectra were investigated in three experimental set-ups and the corresponding appropriate lumped models were formulated. The fit of the proposed lumped models with the measured impedance spectra data was good. The model parameters were correlated with the contact area of the roots and/or stems raised in the hydroponic solution. The EIS method proved a useful non-destructive method for assessing root surface area. This work may be considered to be a new methodological contribution to understanding root systems and their functions in a non-destructive manner.

Diffractive-optics-based sensor as a tool for detection of biocompatibility of titanium and titanium-doped hydrocarbon samples.

Adsorption of the elongated human plasma fibrinogen (HPF) and globular human serum albumin molecules on a titanium-based surface is monitored by analyzing permittivity and optical roughness of protein-modified surfaces by using a diffractive optical element (DOE)-based sensor and variable angle spectro-ellipsometry (VASE). Both DOE and VASE confirmed that fibrinogen forms a thicker and more packed surface adlayer compared to a more porous and weakly adsorbed albumin adlayer. A linear relation of the permittivity (ε(')) and dielectric loss (ε('')) was found for some of the dry titanium-doped hydrocarbon (TDHC) surfaces with excellent HPF adsorption ability. We discuss some aspects of TDHC's aging and its possible effects on fibrinogen adsorption.

An appraisal of the electrical resistance method for assessing root surface area.

Electrical resistances of roots and stems of hydroponically raised willows (Salix schwerinii) were studied and related to root morphology. Willow cuttings with and without roots were set in a constant electric field (effective voltage of 0.1 V, sine-AC, 128 Hz) in a hydroponic solution. The electrical resistance of different components in the measurement system was measured and analysed in relation to root surface area in contact with the cultivation solution. Axial resistivities of single root segments and of stems were measured. The results showed that the resistance decreased in relation to an increase in the contact surface area of the roots with the solution. The resistance depended strongly on the contact area of the stem with the solution, however, thus causing bias in the evaluation of root surface area. This work is a new contribution for the understanding of current pathways in the root system as exposed to an external electric field and for developing a non-destructive method to study plant roots accordingly. It may be concluded that the electrical resistance method is a useful non-destructive method to study roots and their physiological properties. Electrical analogues for roots and stem comprising resistors are discussed in relation to in situ measurements.

Sensing of human plasma fibrinogen on polished, chemically etched and carbon treated titanium surfaces by diffractive optical element based sensor.

Adsorption of human plasma fibrinogen (HPF) on 6 differently treated titanium samples (polished, polished and etched, and 4 titanium carbide coatings samples produced by using plasma-enhanced chemical vapour deposition (PECVD) method) is investigated by using diffractive optical element (DOE) sensor. Permittivity (susceptibility) change and fluctuation in optical roughness (R(opt)) of treated titanium surface in the presence of background electrolyte without and with HPF molecules are sensed by using DOE sensor and optical ellipsometry. Correlation between transmitted light and thickness of molecule layer was found. The findings allow to sense temporal organization and severity of adsorption of nano-scale HPF molecules on polished, on polished and etched, and on titanium carbide surface.

Local and average gloss from flat-faced sodium chloride tablets.

The purpose of this study was to detect local gloss and surface structure changes of sodium chloride tablets. The changes in surface structure were reflected by gloss variation, which was measured using a diffractive optical element-based glossmeter (DOG). By scanning a surface area, we constructed a 2-dimensional gloss map that characterized the tablet's surface structure. The gloss variation results were compared with scanning electron microscopy (SEM) images and average surface roughness values that were measured by conventional diamond stylus profilometry. The profilometry data showed a decrease in tablet surface roughness as a function of compression force. In general, a smoother surface contributes to higher average gloss values. The average gloss values for this material, in contrast, showed a decrease as a function of the compression force. The sequence of particle fragmentation and deformation together with crack formation in sodium chloride particles resulted in a loss of gloss for single sodium chloride particles at the tablet surfaces, which could be detected by the DOG. These results were supported by the SEM images. The results show that detailed information regarding tablets' surface structure changes can be obtained by detection of local gloss variation and average gloss.

Local and average gloss from flat-faced sodium chloride tablets.

The purpose of this study was to detect local gloss and surface structure changes of sodium chloride tablets. The changes in surface structure were reflected by gloss variation, which was measured using a diffractive optical element-based gloss-meter (DOG). By scanning a surface area, we constructed a 2-dimensional gloss map that characterized the tablet's surface structure. The gloss variation results were compared with scanning electron microscopy (SEM) images and average surface roughness values that were measured by conventional diamond stylus profilometry. The profilometry data showed a decrease in tablet surface roughness as a function of compression force. In general, a smoother surface contributes to higher average gloss values. The average gloss values for this material, in contrast, showed a decrease as a function of the compression force. The sequence of particle fragmentation and deformation together with crack formation in sodium chloride particles resulted in a loss of gloss for single sodium chloride particles at the tablet surfaces, which could be detected by the DOG. These results were supported by the SEM images. The results show that detailed information regarding tablets' surface structure changes can be obtained by detection of local gloss variation and average gloss.

Reflectance study of compressed paper.

Reflectance of three paper grades was investigated using a pressure gauge, an imaging system, and a spectrophotometer. It was observed that under high pressure, dark-colored areas appear in paper when using the imaging system. The area of the dark pattern increases as the pressure is raised. Reflectance measurements as a function of wavelength confirmed that the dark patterns appear due to the contact of the paper and the probe window of the pressure gauge. Based on results by other researchers the amount and the nature of optical contact observed depends on structural properties of paper such as surface roughness, formation, and compressibility. Although there are differences in the spectral properties of different paper grades they all share the common feature that the reflectance is decreasing as a function of the applied pressure. An empiric result for the fine and the super-calendered (SC) paper samples measured is that they both have an exponential dependence of total reflectance as a function of applied pressure when the illumination wavelength is kept constant.