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Two distinct microwave power levels and techniques have been studied in two cases: low-power microwave (LPM) irradiation on in vitro Sequoia plants and high-power microwave (HPM) exposure on recovery rates of cryostored (−196°C) Sequoia shoot apices. Experimental variants for LPM exposure included: (a) in vitro plants grown in regular conditions (at 24 ± 1°C during a 16-h light photoperiod with a light intensity of 39.06 μEm −2 s −1 photosynthetically active radiation), (b) in vitro plants grown in the anechoic chamber with controlled environment without microwave irradiation, and (c) in vitro plants grown in the anechoic chamber with LPM irradiation for various times (5, 15, 30, 40 days). In comparison to control plants, significant differences in shoot multiplication and growth parameters (length of shoots and roots) were observed after 40 days of LPM exposure. An opposite effect was achieved regarding the content of total soluble proteins, which decreased with increasing exposure time to LPM. HPM irradiation was tested as a novel rewarming method following storage in liquid nitrogen. To our knowledge, this is the first report using this type of rewarming method. Although, shoot tips subjected to HPM exposure showed 28% recovery following cryostorage compared to 44% for shoot tips rewarmed in liquid medium at 22 ± 1 °C, we consider that the method represent a basis and can be further improved. The results lead to the overall conclusion that LPM had a stimulating effect on growth and multiplication of in vitro Sequoia plants, while the HPM used for rewarming of cryopreserved apices was not effective to achieve high rates of regrowth after liquid nitrogen exposure.

Background, aim, and scope Carbonyl compounds have been paid more and more attention because some carbonyl species have been proven to be carcinogenic or a risk for human health. Plant leaves are both an important emission source and an important sink of carbonyl compounds. But the research on carbonyl compounds from plant leaves is very scarce. In order to make an approach to the emission mechanism of plant leaves, a new method was established to extract carbonyl compounds from fresh plant leaves. Materials, methods, and results The procedure combining derivatization with ultrasonication was developed for the fast extraction of carbonyl compounds from tree leaves. Fresh leaves (< 0.01 g) were minced and ultrasonicated in acidic 2,4-dinitrophenylhydrazine (DNPH)-acetonitrile solution for 30 min and then holding 30 min to allow aldehydes and ketones in leaves to react completely with DNPH. Conclusions The extraction process was performed under room temperature and only took 60 min. The advantages of this method were very little sample preparation, requiring short treatment time and usual equipment. Four greening trees, i.e., camphor tree ( Cinnamomum camphora ), sweet olive ( Osmanthus fragrans ), cedar ( Cedrus deodara ), and dawn redwood ( Metasequoia glyptostroboides ), were selected and extracted by this method. Seven carbonyl compounds, including formaldehyde, acetaldehyde, acetone, acrolein, p -tolualdehyde, m / o -tolualdehyde, and hexaldehyde were determined and quantified. The most common carbonyl species of the four tree leaves were formaldehyde, acrolein, and m / o -tolualdehyde. They accounted for 67.3% in cedar, 50.8% in sweet olive, 45.8% in dawn redwood, and 44.6% in camphor tree, respectively. Camphor tree had the highest leaf level of m / o -tolualdehyde with 15.0 ± 3.4 µg g −1 (fresh leaf weight), which indicated that camphor tree may be a bioindicator of the level of tolualdehyde or xylene in the atmosphere. By analyzing carbonyl compounds from different tree leaves, it is not only helpful for further studying the relationship between sink and emission of carbonyls from plants, but also helpful for exploring optimum plant population in urban greening.

• Premise of the study: Climate-induced forest retreat has profound ecological and biogeochemical impacts, but the physiological mechanisms underlying past tree mortality are poorly understood, limiting prediction of vegetation shifts with climate variation. Climate, drought, fire, and grazing represent agents of tree mortality during the late Cenozoic, but the interaction between drought and declining atmospheric carbon dioxide ([CO2]a) from high to near-starvation levels ∼34 million years (Ma) ago has been overlooked. Here, this interaction frames our investigation of sapling mortality through the interdependence of hydraulic function, carbon limitation, and defense metabolism.• Methods: We recreated a changing Cenozoic [CO2]a regime by growing Sequoia sempervirens trees within climate-controlled growth chambers at 1500, 500, or 200 ppm [CO2]a, capturing the decline toward minimum concentrations from 34 Ma. After 7 months, we imposed drought conditions and measured key physiological components linking carbon utilization, hydraulics, and defense metabolism as hypothesized interdependent mechanisms of tree mortality.• Key results: Catastrophic failure of hydraulic conductivity, carbohydrate starvation, and tree death occurred at 200 ppm, but not 500 or 1500 ppm [CO2]a. Furthermore, declining [CO2]a reduced investment in carbon-rich foliar defense compounds that would diminish resistance to biotic attack, likely exacerbating mortality.• Conclusions: Low-[CO2]a-driven tree mortality under drought is consistent with Pleistocene pollen records charting repeated Californian Sequoia forest contraction during glacial periods (180–200 ppm [CO2]a) and may even have contributed to forest retreat as grasslands expanded on multiple continents under low [CO2]a over the past 10 Ma. In this way, geologic intervals of low [CO2]a coupled with drought could impose a demographic bottleneck in tree recruitment, driving vegetation shifts through forest mortality.

This study evaluated the opportunities and challenges of using drones to obtain multispectral orthomosaics at ultra-high resolution that could be useful for monitoring large and heterogeneous burned areas. We conducted a survey using an octocopter equipped with a Parrot SEQUOIA multispectral camera in a 3000 ha framework located within the perimeter of a megafire in Spain. We assessed the quality of both the camera raw imagery and the multispectral orthomosaic obtained, as well as the required processing capability. Additionally, we compared the spatial information provided by the drone orthomosaic at ultra-high spatial resolution with another image provided by the WorldView-2 satellite at high spatial resolution. The drone raw imagery presented some anomalies, such as horizontal banding noise and non-homogeneous radiometry. Camera locations showed a lack of synchrony of the single frequency GPS receiver. The georeferencing process based on ground control points achieved an error lower than 30 cm in X-Y and lower than 55 cm in Z. The drone orthomosaic provided more information in terms of spatial variability in heterogeneous burned areas in comparison with the WorldView-2 satellite imagery. The drone orthomosaic could constitute a viable alternative for the evaluation of post-fire vegetation regeneration in large and heterogeneous burned areas.

Few studies have quantified pathogen impacts to ecosystem processes, despite the fact that pathogens cause or contribute to regional-scale tree mortality. We measured litterfall mass, litterfall chemistry, and soil nitrogen (N) cycling associated with multiple hosts along a gradient of mortality caused by Phytophthora ramorum, the cause of sudden oak death In redwood forests, the epidemiological and ecological characteristics of the major overstory species determine disease patterns and the magnitude and nature of ecosystem change. Bay laurel (Umbellularia californica) has high litterfall N (0.992%), greater soil extractable NO3– N, and transmits infection without suffering mortality. Tanoak (Notholithocarpus densiflorus) has moderate litterfall N (0.723%) and transmits infection while suffering extensive mortality that leads to higher extractable soil NO3–N. Redwood (Sequoia sempervirens) has relatively low litterfall N (0.519%), does not suffer mortality or transmit the pathogen, but dominates forest biomass. The strongest impact of pathogen-caused mortality was the potential shift in species composition, which will alter litterfall chemistry, patterns and dynamics of litterfall mass, and increase soil NO3–N availability. Patterns of P. ramorum spread and consequent mortality are closely associated with bay laurel abundances, suggesting this species will drive both disease emergence and subsequent ecosystem function.

PREMISE OF THE STUDY: The aboveground tissues of plants host numerous, ecologically important fungi, yet patterns in the spatial distribution of these fungi remain little known. Forest canopies in particular are vast reservoirs of fungal diversity, but intracrown variation in fungal communities has rarely been explored. Knowledge of how fungi are distributed throughout tree crowns will contribute to our understanding of interactions between fungi and their host trees and is a first step toward investigating drivers of community assembly for plant‐associated fungi. Here we describe spatial patterns in fungal diversity within crowns of the world's tallest trees, coast redwoods (Sequoia sempervirens). METHODS: We took a culture‐independent approach, using the Illumina MiSeq platform, to characterize the fungal assemblage at multiple heights within the crown across the geographical range of the coast redwood. KEY RESULTS: Within each tree surveyed, we uncovered evidence for vertical stratification in the fungal community; different portions of the tree crown harbored different assemblages of fungi. We also report between‐tree variation in the fungal community within redwoods. CONCLUSIONS: Our results suggest the potential for vertical stratification of fungal communities in the crowns of other tall tree species and should prompt future study of the factors giving rise to this stratification.

This paper is about the geometric and radiometric consistency of diverse and overlapping datasets acquired with the Parrot Sequoia camera. The multispectral imagery datasets were acquired above agricultural fields in Northern Italy and radiometric calibration images were taken before each flight. Processing was performed with the Pix4Dmapper suite following a single-block approach: images acquired in different flight missions were processed in as many projects, where different block orientation strategies were adopted and compared. Results were assessed in terms of geometric and radiometric consistency in the overlapping areas. The geometric consistency was evaluated in terms of point cloud distance using iterative closest point (ICP), while the radiometric consistency was analyzed by computing the differences between the reflectance maps and vegetation indices produced according to adopted processing strategies. For normalized difference vegetation index (NDVI), a comparison with Sentinel-2 was also made. This paper will present results obtained for two (out of several) overlapped blocks. The geometric consistency is good (root mean square error (RMSE) in the order of 0.1 m), except for when direct georeferencing is considered. Radiometric consistency instead presents larger problems, especially in some bands and in vegetation indices that have differences above 20%. The comparison with Sentinel-2 products shows a general overestimation of Sequoia data but with similar spatial variations (Pearson’s correlation coefficient of about 0.7, p-value < 2.2 × 10−16).

In this study, we examined changes in isotopic (¹³C and ¹⁴C) and spectroscopic (UV and ¹³C NMR) properties of dissolved organic carbon (DOC) in relation to soil organic matter (SOM) to elucidate the sources and sinks of DOC as water percolates through the soils of two contrasting upland coastal California ecosystems--a redwood forest and a coastal prairie. Despite differences in the distribution of C stocks and litter chemistry at these two sites, we found similar shifts in DOC chemistry with soil depth. DOC concentrations dropped rapidly with increasing depth, with an accompanying decrease in the C:N ratio, an increase in the δ¹³C value and an decrease in specific UV adsorption. In the grassland soil, Δ¹⁴C values declined from current atmospheric values (+70[per thousand]) in the surface horizon to -75[per thousand] at 100 cm. In the redwood soil, the Δ¹⁴C value of 111[per thousand] in O horizon leachates was indicative of OM with a residence time of 8-10 yrs, with a decrease in Δ¹⁴C values to -80[per thousand] at 100 cm. Solid-state CP/MAS ¹³C NMR spectra were generally most similar to highly humified OM, with a general decrease in the relative abundance of aromatic compounds and an increase in the alkyl C/O-alkyl C ratio with increasing depth. All of these trends are consistent with the shifts in SOM properties with increasing depth, which are interpreted to mean a shift from fresh plant material to older, highly altered OM. In this Mediterranean climate, we found distinct seasonal shifts in the quantity and composition of DOC found in soil solution during the winter rainy period that was also consistent with a shift from recent labile substrates to older, highly altered OM. These results fit in with a growing body of literature suggesting that the source of much of the DOC within mineral soils is the local soil OM, and the ¹⁴C data, in particular, indicate that DOC at depth is not simply the fraction of surficial leachates that have not been adsorbed or decomposed. Rather, exchange reactions with a portion of the more stabilized SOM pool exert the strongest control on both the concentration and composition of DOC found in these soils.

The decomposition of soil organic carbon (SOC) is intrinsically sensitive to temperature. However, the degree to which the temperature sensitivity of SOC decomposition (as often measured in Q₁₀ value) varies with soil depth and labile substrate availability remain unclear. This study explores (1) how the Q₁₀ of SOC decomposition changes with increasing soil depth, and (2) how increasing labile substrate availability affects the Q₁₀ at different soil depths. We measured soil CO₂ production at four temperatures (6, 14, 22 and 30 °C) using an infrared CO₂ analyzer. Treatments included four soil depths (0–20, 20–40, 40–60 and 60–80 cm), four sites (farm, redwood forest, ungrazed and grazed grassland), and two levels of labile substrate availability (ambient and saturated by adding glucose solution). We found that Q₁₀ values at ambient substrate availability decreased with increasing soil depth, from 2.0–2.4 in 0–20 cm to 1.5–1.8 in 60–80 cm. Moreover, saturated labile substrate availability led to higher Q₁₀ in most soil layers, and the increase in Q₁₀ due to labile substrate addition was larger in subsurface soils (20–80 cm) than in surface soils (0–20 cm). Further analysis showed that microbial biomass carbon (MBC) and SOC best explained the variation in Q₁₀ at ambient substrate availability across ecosystems and depths (R² = 0.37, P < 0.001), and MBC best explained the variation in the change of Q₁₀ between control and glucose addition treatment (R² = 0.14, P = 0.003). Overall, these results indicate that labile substrate limitation of the temperature sensitivity of SOC decomposition, as previously shown in surface soils, is even stronger for subsoils. Understanding processes controlling the labile substrate availability (e.g., with rising atmospheric CO₂ concentration and land use change) should advance our prediction of the fate of subsoil SOC in a warmer world.

PurposeGlobal demand for construction materials has grown exponentially in the last century, contributing to climate change and detrimental impacts on the ecosystem. To aid in sustainable growth and reduce our environmental footprint, renewable construction materials, such as lumber, have been incorporated into green building activities. The purpose of this study was to quantify the environmental impacts associated with manufacturing redwood lumber in northern California using the life-cycle assessment (LCA) approach.MethodsThis study surveyed and visited redwood manufacturing facilities in the US and collected data including lumber production, co-products, resource inputs, and direct emissions to air and water. The life-cycle inventory (LCI) was developed using the mass allocation of products and co-products. Cradle-to-grave (cradle-to-gate and gate-to-grave) LCA method was used to estimate the environmental impacts and energy usage in the production of redwood lumber (1 m3 of lumber), used in a redwood-deck, and its end-of-life (i.e., the deck was demolished after 25 years of its life and redwood lumber disposed of in a landfill that captures methane).Results and discussionsAbout 48% of dry mass in the redwood logs were converted to lumber in the sawmill. Depending on the redwood lumber product analyzed, the cradle-to-gate cumulative fossil energy demand was estimated to be 1862 (522–4877) MJ/m3 of redwood lumber produced. The cradle-to-gate and cradle-to-grave global warming (GW) impact were estimated at 36 (22–65) and 139 (127–167) kgCO2eq/m3 of lumber, respectively. Upstream operations (including silviculture, harvesting, and transport) and mainstream (mill) operations (including sawing, drying, and planing) contributed 53% and 47% of total cradle-to-gate GW impact, respectively. However, the disposal of the redwood lumber products was the most dominant contributor (45–65%) to the cradle-to-grave GW impact of redwood lumber. Carbon stored in the whole lifecycle of redwood lumber is about 4 (range of 3‒5) times more than its cradle-to-grave carbon footprint (CFP), a substantial environmental benefit. Considering credits from co-generation (used mill residues to generate both heat and electricity) supplying renewable electricity to the local grid decreases the net GW impact from − 468 to − 579 kgCO2eq/m3 of lumber. Many redwood lumber products such as decking are used green (freshly-cut), and a large portion of green lumber is only air-dried, which has a much lower GW impact than kiln-dried (force-dried) lumber. Also, even if the lumber requires kiln-drying, the heat comes from burning on-site mill processing residues, considered a carbon–neutral energy source. For lumber production life-cycle stages, kiln-drying of lumber tends to use a lot of thermal energy (albeit mostly from mill residues) compared with the whole life cycle. However, the GW impact from the redwood lumber drying unit process is low, only 27%, because the product tends to be used green. Furthermore, using mill residues to produce on-site combined heat and power (co-generation) was shown to be the most efficient way to reduce the environmental footprints of lumber production.ConclusionOverall, the results showed that redwood lumber production has a negative GW impact and acts as a carbon sink if used in the construction sector. Specifically, the final products store 3–5 times more greenhouse gas emissions over than what is released from cradle-to-grave. There are large differences in GW impact among five categories of redwood lumber products and the rough-green lumber types have the lowest GW impact (or highest GW reduction potential) among all.