Thuja Research Articles

Responses of biological soil crusts to different types of vegetation restoration on the Chinese Loess Plateau: a case study

Biological soil crusts (biocrusts) are important components of dryland ecosystems. Vegetation strongly affects the distribution of biocrusts by influencing the soil stability, moisture and light availability. The Loess Plateau has been subjected to large‐scale restoration efforts; however, the type, coverage, and biomass of biocrusts responses to different types of vegetation restoration remain uncertain. Here, we investigated the biocrust characteristics (type, coverage, thickness, biomass, dominant cryptogam species, and relative abundance of major cyanobacteria and algae) in areas restored with different types of vegetation (Caragana korshinskii, Platycladus orientalis, Armeniaca sibirica, Populus hopeiensis, Pinus tabuliformis, Tamarix chinensis) and in a natural grassland on the Loess Plateau. Our results showed that the coverage, thickness, and biomass of the biocrusts were higher in the natural grassland than in the afforested areas, which suggests that the natural grassland is more suitable than the afforested areas for biocrust distribution. The biocrusts were composed mainly of mosses in the Pi. tabuliformis area and of cyanobacteria and algae in most of the other vegetation restoration areas. However, no biocrusts were observed in the T. chinensis area, probably because the dense canopy prevented light from reaching the soil. In addition, soil properties influenced by vegetation restoration may also affect the characteristics of biocrusts. Overall, our study suggests that natural grassland recovery, rather than afforestation, is likely the most suitable method for the development of biocrusts and provides suggestions for restoration and reconstruction on the Loess Plateau.

Tourist risk assessment of pollen allergy in tourism attractions: A case study in the Summer Palace, Beijing, China.

Pollen allergy has already been an increasingly prominent ecosystem disservice in tourism attractions. However, few studies have assessed the tourist risk of pollen allergy through integrating multidisciplinary knowledge of ecology, medicine, phenology, and risk management. Basing on the conceptual framework of risk assessment proposed by UNISDR, we first established an index system of pollen-allergy risk for tourists in attractions and outlined assessment methods 18 available indexes were put forward to cover three aspects: hazard of plant allergen, tourist vulnerability, and resilience of assessment units. Subsequently, taking the Summer Palace as the case study area, we conducted a tourist risk assessment of pollen allergy. Values of nine available indexes were obtained via ecological investigation, phenological observation, and data mining of visitors' logs on Sina Weibo. Risk levels of spring pollen allergy for tourists in different assessment units were revealed by combining the green zone allergenicity index model and three-dimensional risk assessment matrix. The results showed that: (1) There were seven primary pollen-allergenic plants in the Summer Palace, including Platycladus orientalis, Sabina chinensis, Salix babylonica, Pinus tabulaeformis, Populus tomentosa Carr, Morus alba L. and Fraxinus chinesis, among which Platycladus orientalis and Salix babylonica were the highest allergenic. (2) Among 18 spots, tourists faced the highest risk level of pollen allergy in spring at three spots, namely the Hall of Serenity, Hall of Benevolence and Longevity, and Gallery of Literary and Prosperity. (3) The two routes of the Long Corridor and Longevity Hill scored high on the risk level. (4) Among four areas, risk levels of the Front-hill and Rear-hill areas were high. Given the increasing spatial-temporal uncertainty of pollen allergy and tourist behaviors under global warming and urbanization, the related monitoring should be strengthened in the future. Furthermore, the dynamic and improved assessment of pollen-allergy risk should be institutionalized and be integrated into the evaluation of tourism experience quality. Tourism administration should make full use of relevant assessment results and conduct more effective risk communication.

C, N, P, K stoichiometric characteristics of the “leaf-root-litter-soil” system in dryland plantations

• Tree species and afforestation years affected nutrient cycling of plantations. • The highest C was in fine roots and the highest N, P and K was in green leaves. • Green leaves absorbed more P and maintained P homeostasis to alleviate P limitation. • Caragana korshinskii was more suitable for ecological restoration in drylands. Plantation’s nutrient cycling can regulate and affect the material cycling of ecosystems, which is the key to maintain the sustainable development of the plantation ecosystem. However, the current understanding of the nutrient cycling characteristics of the “leave-root-litter-soil” continuum of dryland plantation ecosystems is limited. Therefore, in the Longzhong Loess Plateau of China, we selected nine typical dryland plantations to carry related research, including two evergreen ( Platycladus orientalis (13-years and 50-years) and Pinus tabuliformis ) and four deciduous ( Caragana korshinskii (13-years, 35-years and 55-years), Armeniaca sibirica , Populus hopeiensis and Tamarix chinensis ) tree species, and measured C, N, P and K contents of green leaves, fine roots, leaf litter and surface soil (0–20 cm). Results showed tree species and afforestation years strongly changed C, N, P and K contents and ratios of green leaves, fine roots, leaf litter and soil components, and also significantly affected leaf N, P and K reabsorption efficiencies. The average N, P and K contents of four components and soil available nitrogen (AN), available phosphorus (AP) and available potassium (AK) contents in deciduous plantations were higher than those in evergreen plantations, resulting in the lower C:N:P:K stoichiometry of deciduous plantations than evergreen plantations. Especially in 55-years C. korshinskii plantation, its soil C, N, AN, AP and AK contents were higher than those in A. sibirica , P. hopeiensis , P. orientalis and P. tabuliformis plantations. Moreover, soil C, N, P, AN, AP and AK contents in C. korshinskii plantations increased significantly with the increase of afforestation years. Thus, C. korshinskii was more suitable for ecological restoration in drylands. Due to the P limitation in plantations, P reabsorption efficiency was higher than N reabsorption efficiency, and significantly negatively correlated with P contents of four components. And green leaves had the homeostasis to soil AP, which may be the nutrient utilization strategies for plantations to alleviate P limitation. Correlation analysis revealed that the C cycling appeared in green leave-fine root and green leave-leaf litter, the N cycling appeared in green leave-leaf litter-soil-fine root, and the P cycling and K cycling appeared in green leave-leaf litter- soil and leaf litter-fine root. These results will provide guidance for ecological restoration and plantation management in drylands.

Absorptive rather than transport root decomposition drives soil carbon sequestration: A case study of Platycladus orientalis and Quercus variabilis

Root litter inputs regulate soil organic carbon stocks and turnover, which is increasingly being understood through a functional trait-based approach. Fine roots of plants are classified into absorptive and transport functional modules. However, the relative contribution of absorptive and transport roots to soil carbon sequestration and the mechanisms involved are still unclear. We conducted a 13-week container incubation experiment using soil from a C4 crop (maize) to investigate the impact of absorptive and transport root litter from Platycladus orientalis and Quercus variabilis on the turnover of new versus old soil carbon at the initial stage of root decomposition. We also measured root chemical properties, soil microbial biomass, and enzyme activity to understand how the two root functional modules regulate soil carbon sequestration differently. Absorptive roots decomposed slower than transport roots due to higher nitrogen content, a larger acid-unhydrolyzable fraction (AUF), and a lower concentration of non-structural carbohydrate (TNC) concentrations. Root litter input reduced the total soil carbon loss and increased soil carbon sequestration, with absorptive root input being more effective than transport roots. More root-derived new carbon was formed by absorptive root addition than by transport roots, likely due to the greater content of recalcitrant compounds in absorptive roots contributing to the formation of particulate organic matter. Old soil carbon loss was stimulated by the addition of transport roots and reduced by the addition of absorptive roots, suggesting a positive priming effect induced by transport roots and a negative priming effect induced by absorptive roots. Furthermore, old soil carbon loss induced by transport roots was significantly positively correlated to the presence of labile substrates and soil enzyme activities. Our results suggest that absorptive roots drive greater soil carbon sequestration than do transport roots. This occurs through more gain of new carbon and less loss of old soil carbon, emphasizing the necessity of distinguishing different root functional modules in predicting the soil carbon cycle.

Discussion of the Distribution Pattern and Driving Factors of 2 Large Old Tree Resources in Beijing

Known as “living fossils”, large old trees play an important role in ecology, landscape, and culture and are an important part of ecosystems and human settlements. The aim of this paper is to provide suggestions for the protection of urban large old tree resources and the selection of large old tree backup resources. First, we conducted a statistical analysis on the composition, distribution, and important values of large old tree species in Beijing and used Downtrend correspondence analysis (DCA) to analyze the composition of different types of habitat tree species. Second, we created a 3 km × 3 km grid within the administrative scope of Beijing, extracted the number of large old trees and tree species richness in the grid, and used geographic detectors to determine the driving factors of the spatial distribution of large old trees, as well as tree species richness differences and their interactions. A total of 40,590 large old trees in Beijing were found, belonging to 72 species, 52 genera, and 29 families. Platycladus orientalis (L.) Franco was the dominant tree species, with an importance value of 0.51. Among the different habitats, the large old trees were found in parks and temples, and the greatest tree species number of old trees were found in communities and the countryside; meanwhile, microgreen spaces had the lowest number of trees and tree species. The distribution of large old trees and tree species was mainly concentrated in the center of the city and the northwest. The distribution pattern of large old tree resources in Beijing is affected by the interaction of various factors. Social factors were the dominant in the distribution of large old tree resources in Beijing. The spatial distribution of large old trees was mainly affected by the scenic resort and historic site (SRHS), and the SRHS and gross domestic product (GDP) level were the most important factors influencing the richness of large old tree species. In addition, the functional value and characteristics of tree species determined the distribution of large old tree habitats. Therefore, the protection of large old tree resources requires developing scientific management and planning by managers, increasing investment in management and protection, and strengthening ecological culture publicity.

Effects of Different Vegetation Types on Soil Microbial Functional Genes and Enzyme Activities in Reclaimed Coal Mine

Long-term coal mining has seriously damaged soil structures and ecological environments. Reclaimed vegetation could effectively improve the ecological environment. There have been many studies on soil physical-chemical characteristics and microbial community structure, but there are few on soil functional microorganisms in mining areas. In this study, soil physical and chemical properties, soil enzyme activities, and the abundance of functional genes in carbon, nitrogen, phosphorus, and sulfur cycling were determined in five reclaimed lands of different vegetation types (Platycladus orientalis, Picea asperata, Pinus tabuliformis, Pinus sylvestris, and Sabina chinensis) in the Jinhuagong mining area, Datong City, Shanxi province. The results showed that the restoration types produced significant effects on soil physical and chemical properties, soil enzyme activities, and the abundance of 75 functional genes. The highest contents of total carbon, total nitrogen, and total sulfur were in the S. chinensis site. The activities of dehydrogenase and urease were the highest in P. asperata, and the lowest alkaline protease activity was in P. asperata. The alkaline protease activity was the highest in P. sylvestrist. The abundance of functional genes in the P. asperata forest was the highest, but the diversity index was significantly lower than that in other plots, which might be due to the fact that the total abundance of ureC, acsA, and mct in P. asperata accounted for more than 52%. Soil urease was significantly correlated with the abundance of six functional genes. The β diversity of the functional microbial community was significantly different among the different vegetation types, indicating that functional genes could better explain the effects of vegetation types on microbial function. The highest and lowest integrated fertility indexes were found in the P. sylvestris and P. orientalis plots, respectively. In conclusion, soil functional genes are sensitive indicators signifying the effects of different reclamation types on soil microorganisms, and P. asperata and P. sylvestris are more suitable for reclamation in this mining area.

Response of Soil Moisture to Long-Duration Rainstorms in Three Forest Stands in Mountainous Areas of North China

Rainfall is one of the core components of the water cycle in terrestrial ecosystems and is closely related to hydrothermal balance, plant and animal growth, and stability of the whole ecosystem. Long-duration rainstorms can alter the soil structure of forest ecosystems and affect the spatial distribution of soil moisture, thus affecting the water supply from the soil to trees and being one of the factors that increase the vulnerability of forest ecosystems. In recent years, changes in rainfall patterns have normalized prolonged heavy rainfall in the mountainous areas of North China. However, there are few reports on the response of soil water at different depths to historically long rainstorms in forested areas. By quantifying the relationship between precipitation characteristics and soil water, the soil water transport patterns of Platycladus orientalis (PO), Quercus variabilis (QV) and Pinus tabuliformis (PT) during the long-duration rainstorms of 21–22 July 2012 were evaluated separately, and the roles of different plants in response to the historically long rainstorm were determined. The results showed that (1) the response of different forest stands to rainfall had a lag. Among them, the soil water of PO and PT were less affected by rainfall and could maintain a relatively stable state. (2) The soil moisture transport trend of PO was significantly greater than that of other vegetation zones and covered the whole process of rainfall. Under the three typical vegetation covers, there was a continuous zero-flux plane in the soil at each observed depth (the direction of soil moisture flow is more stable over the rainfall period), but there was no regular transport trend. (3) The root system was an important factor, influencing the differences in soil moisture response of the three vegetation types. QV had a higher average effective water recharge rate than lateral cypress and oleander and could better utilize the water recharge from storm water.

Biorational Control of Callosobruchus maculatus (Coleoptera: Buchidae) in Stored Grains with Botanical Extracts.

Globally, around 2000 plant species are used against pest control. The utilization of botanicals is considered the most economic and biodegradable methods for the control of stored grains pests. Therefore, the current study was carried out to investigate the repellency potential of five botanicals against Callosbruchus maculatus F. in Haripur, Pakistan. The concentrations of Azadirachta indica L., Nicotiana tabacum L., Melia azedarach L., Nicotiana rustica L., and Thuja orientalis L. were, i.e., 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0% in four replicates to establish contact effects. The data were recorded after 1, 2, 3, 6, 24, 48, 72, and 96 hours. The repellency effect of these plant species against C. maculatus were increased in both the time- and dose-dependent manner, and highest effect was observed at 72 h. In addition, the repellency effect was 91% for A. indica (class: V), 86% M. azedarach, 82%, N. tabacum (class: V), 79% N. rustica (class: IV), and 75% T. orientalis (class: IV) at 3% concentration against C. maculatus. Furthermore, following 96 hours' exposure to treatment the sensitivity response of insects decreases as the time interval increases, i.e., 86% A. indica (class: V) was followed by 71% M. azedarach (class: IV), 65% N. tabacum (class: IV), 61% N. rustica (class: IV), and T. orientalis 57% (class: III) repellency at highest concentration of 3%. The current study concluded that A. indica and M. azedarach can be incorporated for the management of C. maculatus and these plant species might be helpful in the productions of new biopesticides.

Adaptability of tree water use to elevation changes: A case study of a mixed forest in Northern China

Global climate change may influence the distribution and water uptake patterns of plants in the rocky mountainous areas of North China. The change in climatic conditions with elevation in mountainous areas provides an opportunity to understand the potential impacts of global climate change on plant water use. To assess the responses and adaptations of plants to the elevations, three aspects were investigated for Platycladus orientalis (L.) Franco and Pinus tabuliformis Carrière, namely source of water used, water use efficiency (WUE), and specific leaf area (SLA). These aspects were assessed for the selected species along an elevation from 100 to 1000 m (100, 400, 700, and 1000 m) in a seasonally arid area. The results showed that the soil water contents were significantly and positively correlated with the elevation (P < 0.05). The soil water content increased by 0.33% for every 100 m increase in elevation. P. orientalis (L.) Franco was sensitive to the change in elevation and showed plasticity with regard to the water source used, while P. tabuliformis Carrière was not. P. orientalis mostly used water from the 60–100 cm soil layer (28.6–33.8%) and groundwater (27.8–36.2%) at four elevations. The water utilization ratio of P. orientalis at the 60–100 cm soil layer and groundwater decreased with elevation, while that at the 0–20 and 20–60 cm soil layers increased gradually with elevation. The water sources of P. tabuliformis exhibited no variation with elevation and growing stages. P. tabuliformis obtained over 60% of the water from the 60–100 cm soil layer (27.8%) and groundwater (35.9%), while small amounts were from the 0–20 and 20–60 cm soil layers. The SLA of P. tabuliformis and P. orientalis decreased by 0.73 and 0.70 cm2/g, respectively, for every 100 m elevation. The SLA and WUE were significantly and negatively correlated with elevation. At the same elevation range, the SLA of P. tabuliformis was 1.5% higher than that of P. orientalis, while the WUE of P. tabuliformis was 3.4% lower than that of P. orientalis. The results indicated that P. orientalis was better adapted to environmental changes than P. tabuliformis. P. orientalis can change its source of water, improve WUE, and reduce SLA to adapt to the change in elevations, showing a synergistic adaptation to elevation. However, P. tabuliformis showed trade-off adaptation to elevation by adjusting only WUE and SLA.

Green Synthesis of Silver Nanoparticles for Preparation of Gelatin Films with Antimicrobial Activity.

Silver nanoparticles were successfully synthesized using Thuja orientalis aqueous extract and AgNO3 as a precursor. UV–Vis showed a distinct absorption peak at 424 nm attributed to silver nanoparticles due to their surface plasmon resonance. Atomic absorption analysis reflected an increase in the concentration of nanoparticles in relation to the progress of the synthesis, obtaining a peak concentration value of 15.7 mg/L at 50 min. The FTIR spectra revealed the characteristic functional groups of phytomolecules involved in the silver–ion binding process, such as R–O–H (3335 cm−1) O=C–OH (2314 cm−1) and C—C=C (1450 cm−1). At 50 min, zeta potential showed the stability of the nanoparticles with the value of −21.73 mV. TEM micrographs revealed the formation of spherical nanoparticles with an average size of about 85.77 nm. Furthermore, films incorporated with nanoparticles exhibited a Tg from 66.42 °C to 73.71 °C and Tm at 103.31 °C. Films from the G22 formulation presented excellent antibacterial properties inhibiting the growth of Staphylococcus aureus. Thuja orientalis aqueous extract could be a low-cost, eco-friendly, and efficient reducing and capping agent for the synthesis of nanometric-sized Ag particles. Gelatin films with nanoparticles are expected to have high potential as an active food packaging system.

Variations of soil organic carbon fractions in response to conservative vegetation successions on the Loess Plateau of China

Land use changes profoundly affect the equilibrium of soil organic carbon (SOC) sequestration and greenhouse gas emissions. With the current global climatic changes, it is vital to understand the influence of ecological restoration and conservation management on the dynamics of SOC under different land uses, especially in erosion-endangered Loess soils. Therefore, we investigated changes in SOC through a suit of labile fractions, namely: light fraction organic C (LFOC), heavy fraction organic C (HFOC), coarse particulate organic C (CPOC), fine particulate organic C (FPOC), and dissolved organic C (DOC), from two forests i.e., Robinia pseudoacacia (RP) and Platycladus orientalis (PO), with different ages, in comparison with farmland (FL). The SOC and STN contents significantly increased over 42 years in the RP forest where the contents of CPOC and FPOC were significantly higher than in the FL. Moreover, total SOC and its labile fractions, in the studied land use types, significantly correlated with soil CaCO3, pH, and STN contents, indicating their key roles in SOC sequestration. The results reported here from different vegetation with different ages provide a better understanding of SOC and STN alterations at different stages of vegetation restoration. Our findings suggest that long-term natural vegetation restoration could be an effective approach for SOC sequestration and soil conservation on the Loess soil.

Presence of Thysanoptera Species in the Urban Green Spaces of Iran: New Records Along with Illustrated Type Specimens

We present a list of Thysanoptera species found in the Mashhad metropolitan region (north-east of Iran). A total of 24 sampling sites were set up on Pinus mugo Turra and Platycladus orientalis (L.), two ornamental trees important commonly found in urban areas, to better understand the fauna and distribution of thrips populations. Thysanoptera fauna consists of 13 species in eight genera, two subfamilies and three families, of which three have never been recorded in Razavi Khorasan province. In terms of species, the highest number of species belonged to the family Thripidae. The present study tentatively suggested that P. mugo and P. orientalis attract most species of adult thrips (Thysanoptera) but do not support reproduction. We examined and illustrated the types of eleven of currently accepted synonyms of Haplothrips reuteri (Karny, 1907), H. subtilissimus (Haliday, 1852), Aptinothrips rufus (Haliday, 1836), Chirothrips africanus Priesner, 1932, C. manicatus (Haliday, 1836), Thrips atratus Haliday, 1836, and T. vulgatissimus Haliday, 1836, together with information on distributions and diagnosis that are useful for recognising each species. The purpose of this study is to fill in the knowledge gaps regarding the distribution of Thysanoptera in the diverse urban green spaces (UGSs).

Study on Transpiration Water Consumption and Photosynthetic Characteristics of Landscape Tree Species under Ozone Stress

Using Pinus bungeana, Platycladus orientalis, Koelreuteria paniculata and Ginkgo biloba as research objects, three open-top chambers with different ozone-concentration gradients were set up (NF, NF40 and NF80) based on trunk sap-flow technology to study the difference in ozone absorption by trees under different ozone concentrations. The results showed that the monthly and diurnal variations of sap-flow density of different tree species decreased with the increase in ozone concentration, and the increase in ozone concentration reduced the water consumption, ozone uptake rate (FO3), net photosynthetic rate (Pn) and water-use efficiency (WUE) of different tree species. The sap-flow density, water consumption, FO3 and WUE of Koelreuteria paniculata and Ginkgo biloba were higher than those of Pinus bungeana and Platycladus orientalis under different ozone concentrations. The sap-flow density, water consumption, FO3 and WUE of Koelreuteria paniculata and Ginkgo biloba decreased significantly at the ozone concentrations of NF40 and NF80; compared with the ozone concentration of NF, the sap flow density of Koelreuteria paniculata and Ginkgo biloba decreased by 1.04 and 1.03 times as much as that of Pinus bungeana and Platycladus orientalis, respectively; the water consumption of Koelreuteria paniculata and Ginkgo biloba decreased by 1.82 and 1.56 times that of Pinus bungeana and Platycladus orientalis, respectively; the decline rate of FO3 in Koelreuteria paniculata and Ginkgo biloba was 1.30 and 1.04 times that of Pinus bungeana and Platycladus orientalis, respectively; and the decline rate of WUE of Koelreuteria paniculata and Ginkgo biloba was 1.52 and 1.64 times that of Pinus bungeana and Platycladus orientalis, respectively. Pinus bungeana and Platycladus orientalis have stronger tolerance to ozone, while Koelreuteria paniculata and Ginkgo biloba were weak. A variety of conifers can be planted in areas with serious ozone pollution.

The Water Storage Function of Litters and Soil in Five Typical Plantations in the Northern and Southern Mountains of Lanzhou, Northwest China

Soil and water conservation is an important function of forest ecosystems; however, it remains unclear which forest type is best suited for water and soil conservation under the same site conditions. In order to clarify the soil and water conservation function of different plantations in the northern and southern mountains of Lanzhou city, we investigated several soil and water conservation function indicators (thickness and accumulation of litter, maximum water holding capacity and rate of litter, water holding capacity and water absorption rate of litter, soil infiltration rates, soil water content, soil bulk density, soil porosity, and soil water storage) of five plantation types (Platycladus orientalis plantations (Po), Robinia pseudoacacia plantations (Rp), Populus alba var. pyramidalis plantations (Pa), P. alba var. pyramidalis + R. pseudoacacia mixed plantations (Pa + Rp), and P. orientalis + R. pseudoacacia mixed plantations (Po + Rp)) and evaluated them using the gray correlation method. The results indicated the accumulation of litter varied from 13.50 to 47.01 t·hm−2 and increased in the order of Pa &lt; Rp &lt; Po &lt; Po + Rp &lt; Pa + Rp. The maximum water holding capacity of litter varied from 35.29 to 123.59 t·hm−2 and increased in the order of Pa &lt; Rp &lt; Po &lt; Po + Rp &lt; Pa + Rp. The soil physical properties (soil infiltration, porosity, and bulk density) of mixed plantations were better than those of pure plantations. The soil maximum water storage was significantly different among plantation types (p &lt; 0.05), with an average varying from 3930.87 to 4307.45 t·hm−2, and was greater in mixed plantations than in pure plantations. Gray correlation analysis revealed that mixed plantations had the best conservation function of the five plantation types, followed by broad-leaved plantations and coniferous plantations. This suggests that the planting of mixed plantations dominated by Pa + Rp is therefore recommended in the future construction of plantations in the northern and southern mountains of Lanzhou to realize sustainable forest development.

Essential oil extraction and evaluation from the fresh Platycladus orientalis (L.) Franco seed peel waste by an environment-friendly method

In this study, the essential oil was extracted and characterized from fresh seed peel waste of Platycladus orientalis (L.) Franco by enzymatic pretreatment combined with solvent-free microwave extraction method (EP-SME) for the first time. The optimal preparation conditions were obtained by single-factor and response surface optimization. Under the optimum conditions, the essential oil yield was 1.13%, which was 24.18% higher than that by traditional steam distillation method (SD) (0.91%), and the essential oil was rich in more polyphenols and flavonoids. The results of gas chromatography-mass spectrometry showed that the essential oil from EP-SME method had the high percentage of oxygenated compound (13.38%). Compared with SD method, the content increments of the first three components were cedrol (+4.91%), 2-carene (+2.31%), caryophyllene (+0.81%), respectively. In addition, the essential oil from the EP-SFME method showed higher comprehensive antioxidant activity and stronger acetylcholinesterase inhibitory activity than those from the hydrodistillation method. The results of extraction kinetics and energy consumption showed that EP-SME method had high extraction efficiency and reached the extraction equilibrium point in a short time (50 min). Its energy consumption and gas emission were only 15.16% of SD.

Species-specific efficiency in PM2.5 removal by urban trees: From leaf measurements to improved modeling estimates

The growing population in cities is causing a deterioration of air quality due to the emission of pollutants, causing serious health impacts. Trees and urban forests can contribute through the interception and removal of air pollutants such as particulate matter (PM). The dry deposition of PM by vegetation depends on air pollutant concentration, meteorological conditions, and specific leaf traits. Several studies explored the ability of different plant species to accumulate PM on leaf structures leading to the development of models to quantify the PM removal. The i-Tree Eco is the most used model to evaluate ecosystem services provided by urban trees. However, fine particulate matter (PM2.5) removal is still calculated with a poorly evaluated function of deposition velocity (which depends on wind speed and leaf area) without differentiating between tree species. Therefore, we present an improvement of the standard model calculation introducing a leaf trait index to distinguish the species effect on PM net removal. We also compared model results with measurements of deposited leaf PM by vacuum filtration. The index includes the effect of morphological and functional leaf characteristics of tree species using four parameters: leaf water storage, deposition velocity, resuspension rate and leaf washing capacity. Leaves of 11 common urban tree species were sampled in representative areas of the city of Ferrara (Italy) and at different times of the year from 2018 to 2021. This includes four deciduous broadleaf trees (Tilia cordata, Platanus acerifolia, Acer platanoides, Celtis australis), three evergreen broadleaf trees (Quercus ilex, Magnolia grandiflora, Nerium oleander), and four conifers (Thuja orientalis, Cedrus libani, Pinus pinaster, Picea abies). The results provide significant advancement in assessing PM removal using decision support tools such as models to properly select tree species for future urban tree planting programs aimed at improving air quality.

Cones of Coniferous Taxa as a Potential Source of Bioactive Polyphenols

Background: Coniferous cones are a by-product of forestry and wood logging, used for many possible purposes, e.g., the extraction of polyphenols. Objective: The aim of the present article was the comparison of the antioxidant polyphenol content of the differently matured cones of 17 selected conifers, either common in Hungary or yet uninvestigated. Methods: Total polyphenol content, ferric reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl assays were used to determine the antioxidant contents. A scoring system was implemented using the three assay results to evaluate and compare the overall antioxidant power of the samples. Result and Conclusion: Highest antioxidant contents were found in green cones, followed by mature and opened cones. Taxa with the highest scores were Tsuga canadensis, Cryptomeria japonica, Chamaecyparis lawsoniana, Thuja orientalis, Metasequoia glyptostroboides and Picea abies. For the samples with the highest overall antioxidant power the high-performance liquid chromatographic/ tandem mass spectrometric polyphenol profiling was carried out (green cones of T. canadensis and P. abies) and 83 compounds have been tentatively identified and described. Results contribute to the future bioactivity testing and evaluation of the cone extracts of T. canadensis and P. abies.

Competition and Niche Differentiation of Water and Nutrients between Broussonetia papyrifera and Platycladus orientalis under Prolonged Drought Stress

Little is known about the competition between and niche differentiation of water and nutrients between angiosperm and gymnosperm tree species under prolonged drought stress, especially in fragile environments. We imposed 21 d drought and competition treatments on Broussonetia papyrifera and Platycladus orientalis and measured water, N, and P contents, the isotopic composition of N and C, the activity of P assimilation enzymes, and stomatal conductance under solo planting and mixed planting to characterize resource diversity and competition in response to treatments. The N content, δ13C, δ15N, phosphomonoesterase, phosphodiesterase, gs, and foliage water content were significantly affected by the soil water content. The δ15N content in young leaves showed that N competition between these two plants could be alleviated through niche differentiation, but the changes in the PDE: PME ratio for these two plants indicated that they lost the niche differentiation of the P source under drought stress. Additionally, it was observed that foliage water content, WUE, N contents, and N and P sources were significantly affected by interspecific competition, and Broussonetia papyrifera benefited from water competition under moderate drought. Our results indicate that plants have different competition and niche differentiation modes to different nutrients under drought stress, and the effect of interspecific water competition should be seriously considered in mixed forests in semiarid areas.

Gas chromatography-ion mobility spectrometric discrimination of trunk borer infested Platycladus orientalis using a novel topographic segmentation strategy

Gas chromatography coupled with ion mobility spectrometry (GC-IMS), a volatile analysis technique, has been widely used in the agricultural field over the past decade. However, complex three-dimensional (3D) fingerprint, including millions of data elements, causes significant challenges for its data process. This study proposed a novel topographic segmentation-based strategy, which could automatically extract the maxima and volume features from individual peaks. Compared with the manual marker selection approach, its efficiency was identified using different classification and prediction models based on trunk borer infested Platycladus orientalis samples. The grid search-support vector machine (GS-SVM) classifier combined with a topographic segmentation strategy could correctly classify at least 93.67% of P. orientalis samples into their corresponding infestation stages. The volume feature performed best, and its cross-validation classification accuracy could reach 97.05%. The PLSR prediction model based on the volume feature got the most satisfactory result, whose Rc2 = 0.9624 and RMSEC = 6.328 in calibration set and Rp2 = 0.9056 and RMSEP = 9.926 in validation set. In a word, our proposed topographic segmentation strategy had enough capability to extract local maxima and volume features of peaks from GC-IMS fingerprints. The GC-IMS-based approach combined with chemometric methods had the potential to discriminate the infestation stages of trunk borer damaged P. orientalis plants.

A semi-thin section technique-based approach to quantify the xylem secondary cell wall deposition process

Summary Identification of wood formation, cell wall deposition, lignification, and the maturation process contribute to a better understanding of biomass accumulation processes. Traditional methods for studying xylem development are limited by dyeing effects and discrimination experience, are non-quantitative for the degree of cell wall deposition and lignification, or are unsuitable for broad-leaved trees. In this study, we integrated several already existing methods to improve the discriminative accuracy of the cell development stage and to quantitatively describe the cell wall deposition and lignification degree for both softwood and hardwood tree species. To do this, we collected tree microcores every 7–14 days during a growing season for two species, one conifer (Platycladus orientalis) and one broad-leaved tree (Acer truncatum), in the mountainous areas in Beijing, China. We tracked the xylem development using semi-thin section technology combined with polarization microscopy. This integrated approach allows a quantitative description of the xylem cell wall deposition and lignification process of both hardwood and softwood tree species. This approach can be applied to demonstrate the dynamic process between the cambium layer and the production of wood cells and to describe the cell wall deposition and lignification process of wood cells from generation to maturation. This approach has certain application prospects for exploring scientific issues related to wood formation and accumulation processes in forestry and ecological studies.