Thuja Research Articles

In vitro Genotoxicity and In silico Docking Analyses of the Essential Oils of Thuja orientalis.

Two main objectives were pursued to assess the reliability of Thuja orientalis essential oils (TOEO). The first objective was to extract TOEO, analyze them by GC-MS, and determine their in vitro genotoxicity against selected plants using the RAPD-PCR method. The second objective was to evaluate the in-silico toxicity of TOEO. The binding sites and energies of each content was calculated against B-DNA. In-silico analyses were performed using a simulation program, AutoDock Vina, and Toxicity Estimation Software Tools. 3-carene, cedrol, and 2-pinene were identified as the predominant components. In vitro studies showed that the TOEO had a more significant impact on reducing genomic stability in wheat compared to the amaranth. The lowest stability was determined as 39.78 % in wheat and 53.58 % in amaranth. Cedrol (-5,7 kcal/mol) and selinene (-5,6 kcal/mol) exhibited the highest binding affinity. The toxicity test indicated that components other than cyclohexene may have toxic effects, none of them were predicted to be mutagenic, and LD50 (mol/kg) values could vary between 1.33 and 1.55.

Landscaping of settlements in the Aral Sea disaster zone (Kazakhstan)

The role of landscaping in ameliorating the environmental conditions within settlements surrounding the Aral Sea is paramount. The primary natural constraints affecting the proliferation of plant species in the green spaces of Aralsk include low winter temperatures, elevated summer temperatures, meager precipitation, and susceptibility to windstorms. An evaluation of the species composition of tree and shrub vegetation was conducted in landscaped areas belonging to social and cultural facilities, as well on private residential property, within the municipal boundaries of Aralsk. Plantings surveyed encompassed an area of approximately 34,000 m2. 89.5% of the flora is comprised of five predominant taxa: Ulmus pumila, Populus x canadensis, Haloxylon ammodendron, Platycladus orientalis, and Acer negundo. These species demonstrate resilience to both high and low temperatures throughout the growing season, and their availability as planting material in the region further enhances their suitability. Presently, the city incorporates 31 taxa of tree and shrub species in its green spaces. Notably, Ulmus glabra, Catalpa ovata, Platanus orientalis, Hibiscus syriacus, and Prunus padus have been introduced and were not previously observed in the city. Analysis of the age distribution reveals 68.7% of young trees, underscoring ongoing landscaping efforts within the city even amid a shortage of irrigation water.

Spectral phenology features of Platycladus orientalis (L.) Franco

Spectral plant phenology, based on time series of vegetation indices, is a useful tool for monitoring vegetation condition and climatic changes. The chlorophyll/carotenoid index (CCI) and photochemical reflectance index (PRI) show promise for spectral phenology of coniferous plants. This study evaluates the potential of using CCI, PRI, and the normalised difference vegetation index (NDVI) as phenological metrics for Platycladus orientalis. The study found a strong correlation between the annual dynamics of the chlorophyll/carotenoid ratio (Chl/Car) and the time series of CCI (R2 = 0.89, p < 0.001) and PRI (R2 = 0.85, p < 0.001). The CCI time series was used to determine the beginning and end of the phenological vegetation period (PVP) of P. orientalis through a double logistic regression model. The PRI model had an error of approximately two weeks in predicting the beginning and end of the PVP, with a tendency to overestimate the duration of the PVP. The use of NDVI as a model is unsuitable for describing the P. orientalis 2023 PVP.

GC-MS profiling and anti-bacterial activity of Thuja orientalis in reference of plant biodiversity

GC-MS profiling and anti-bacterial activity of Thuja orientalis in reference of plant biodiversity

Molecular probing of wilt etiology in Thuja orientalis, and pathogen confirmation through Koch’s Postulates

Thuja orientalis a monoecious widely grown ornamental plant in Pakistan. T. orientalis plants were observed being severely attacked by Fusarium wilt during a survey of the landscape areas of District Faisalabad. Infected plants had severe symptoms of leaves wilting, chlorosis, and necrosis. Wilt disease-affected samples of Thuja orientalis were collected from the University of Agriculture, Faisalabad, Pakistan, in 2017. The associated pathogen was identified based on morphological characters and molecular characterization by using ITS primers (ITS1-F/ITS4) specific to ITS regions of ribosomal RNA (rRNA) of the fungus. The morphologically characterized fungal isolates were used in pathogenicity. In the pathogenicity test, inoculated plants were compared with control plants (sprayed with distilled water). After 3-4 weeks, inoculated plants showed typical chlorosis symptoms. Pathogenicity test proved the F. solani as pathogen of wilt disease on Thuja. Keywords: Thuja orientalis, Morpankh, Fusarium solani, Fusarium wilt, pathogenicity.

Understory vegetation diversity patterns of Platycladus orientalis and Pinus elliottii communities in Central and Southern China.

As a vital component of arbor forests, understory vegetation serves as an essential buffer zone for storing carbon due to its strong capacity for community regeneration. This study aimed to identify the diversity pattern and construction mechanism of Platycladus orientalis and Pinus elliottii understory vegetation based on large-scale sample surveys. The Bayesian Information Criterion value of species abundance distribution (SAD) indicated that the Zipf and Zipf-Mandelbrot models were the best-fitting models. The SAD and gambin fitting results suggested that the Pi. elliottii community had a more balanced structure, with most species being relatively abundant. The multiple regression tree model detected four and six indicator species in P. orientalis and Pi. elliottii communities, respectively. The α-diversity index increased with a rise in altitude and showed a wavy curve with latitude. Linear regression between the β diversity and environmental and geographic distance indicated that the P. orientalis and Pi. elliottii understory communities tended to be dominated by different ecological processes. The partition of β diversity indicated that both communities were dominated by turnover processes, which were caused by environmental classification or spatial constraints. This study helped to understand the diversity maintenance in the P. orientalis and Pi. elliottii understory vegetation communities, and will benefit for diversity restoration and conservation of pure conifer forests.

N-doped defect-rich porous carbon nanosheets framework from renewable biomass as efficient metal-free bifunctional electrocatalysts for HER and OER application

In response to the demand for clean, renewable energy sources and storage technologies, innovative materials and combinations have been developed at reasonable prices as effective electrode materials. Current research and development of carbon-based metal-free catalysts have opened up new research areas for bifunctional electrocatalysts for overall water splitting. Herein, we developed N-self-doped defect-rich porous carbon nanosheets derived from platycladus orientalis tree-cone biomass for overall water splitting. The developed N-self-doped defect-rich porous carbon nanosheets have large surface areas (3369 m2/g), high pore volumes (2.1 cm3 g−1), and high electrical conductivities (12.69 S/cm). N-self-doped defect-rich porous carbon nanosheet framework was employed in water splitting as a dual function in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Electrodes fabricated from the KOH-II ABC nanosheets show excellent OER and HER performances in the 0.5 M H2SO4 solution. The current density of 10 mA cm−2 is reached at a low overpotential of 90 mV for OER and 188 mV for HER. In addition, KOH-II ABC nanosheets also show a remarkable performance on overall water splitting, which only required a cell voltage of 1.49 V to reach current densities of 10 mA cm−2 in 0.5 M H2SO4 solution. The presence of defects in the carbon nanosheets, higher specific surface area, excellent electrochemical active surface area and N doping effectively enhance the reaction kinetics for attaining efficient OER and HER performances. This facile approach to preparing biomass-derived N-doped defect-rich porous carbon materials empowers next-generation green fuel conversion technologies for carbon neutrality.

The soil microbial necromass carbon and the carbon pool stability drive a stronge priming effect following vegetation restoration

The priming effect stands as a critical factor influencing the balance of soil organic carbon (SOC). Following vegetation restoration, the carbon (C) pool stability in Platycladus orientalis forests (PO) varies, and the priming effect resulting from exogenous C addition also differs significantly. Here, we selected PO with restoration ages of 10, 15, and 30 years in the rocky mountainous area in northern China and conducted measurements of soil properties, microbial communities, microbial necromass C (MNC), SOC fractions, and the priming effect characteristics to explore the main influencing factors of the priming effect, especially the microbiological mechanisms. Our results showed that the ratio of mineral-associated organic C to particulate organic C increased. The characteristics of the priming effect showed the same pattern, and there was a significant positive correlation between the C pool stability and the priming effect. The diversity of the fungal communities increased with increasing vegetation restoration age, and the content and proportion of fungal necromass C (FNC) also increased synchronously, reaching the maximum value in the soil of PO that had been restored for 30 years. In addition, the soil water content and total nitrogen indirectly affected the priming effect by influencing the microbial communities. In summary, the results suggested that vegetation restoration can enhance the C pool stability by promoting an increase in soil FNC, thereby producing a positive priming effect. This can help deepen our understanding of the SOC mineralization changes induced by fresh C input following vegetation restoration and provides a theoretical basis for better explaining the C cycle between soil and atmosphere under the vegetation restoration models in the future.

A Study on the Preparation and Stability of Natural Cleaning Agents for Excavated Gold Leafed Clothing Relics

The aim of this study was to develop a natural cleaning agent for the conservation treatment of excavated gold leafed clothing artefacts and to test the stability of its application. To this end, a natural cleaning agent was formulated by mixing the extracts of Platycladus orientalis with natural cleaning aids prepared using coconut oil, rice kernel oil, and castor oil. The prepared natural cleaning agent was found to have better cleaning power and stability as a cleaning agent for clothing relics, compared to Saponin, Decyl glucoside, and Triton X-100, which have been conventionally used as cleaning agents for excavated clothing relics. A comparison of the four types of cleaning agents showed that the natural cleaning agent prepared with the extracts of Platycladus orientalis has significantly better cleaning power compared to three low and high concentration cleaning agents that have been used as cleaning agents for clothing relics. The findings show that the pH of the prepared natural cleaning agent was neutral, ranging from 6.61 to 6.93, indicating very weak acidity, the natural cleaning agent did not cause any pH related problems to the fabric during or after cleaning, and the prepared natural cleaning agent can be used as a stable natural agent for clothing relics because it has better cleaning power than the other conventional cleaning agents even at a relatively low concentration of 0.5% to 1.5%, a treatment time of 30 min., and a temperature below 30°C, a temperature which is not damaging to clothing relics.

Mechanisms of trunk cavity formation of large old trees in urban landscapes: A case study on four tree species in Beijing

Cavity trees play a crucial role in enhancing urban biodiversity, despite limited habitat space. Understanding these aspects is of paramount importance for promoting biodiversity in urban environments. Nevertheless, there is a paucity of extensive research on the characteristics and formation mechanisms of cavity trees across diverse tree species in urban landscapes. In this study, Arbotom sonic tree tomography was used to identify cavity cores within four representative large old tree species in Beijing, encompassing two broadleaved species [Styphnolobium japonicum (L.) Schott, n = 301; and Ginkgo biloba L., n = 100] and two conifer species [Platycladus orientalis (L.) Franco, n = 515; and Pinus tabuliformis Carr., n = 404]. We introduce a cavity index to quantify tree decay and explore cavity characteristics and formation mechanisms across different tree species. Our results reveal that the cavity index is primarily linked to diameter at breast height (DBH), tree age, and trunk health in the four large old tree species studied. The formation of cavities in trees is primarily attributed to external disturbances that lead to tree damage. Subsequent fungal infections occur when a tree's defense mechanisms fail to prevent them, resulting in trunk decay and the formation of cavities. It is worth noting that different tree species exhibit varying defense mechanisms, with coniferous species generally displaying stronger defenses than broad-leaved species. In summary, the formation of cavity trees in urban landscapes is influenced by a combination of internal and external factors, with the tree species' defense mechanisms and the extent of external disturbances determining cavity characteristics. The findings indicate a higher likelihood of cavities in the outer parts of large old trees in southern regions compared with those in northern regions. Coniferous species also exhibited fewer cavities than broad-leaved species. Further, urban trees are more susceptible to external damage that can lead to cavity development, thereby necessitating attention to their growth environment and morphological conditions. However, understanding these factors can aid managers in crafting conservation policies that enhance urban biodiversity and provide habitats for urban wildlife, thereby maximizing the societal benefits.

Tree Crown Affects Biomass Allocation and Its Response to Site Conditions and the Density of Platycladus orientalis Linnaeus Plantation

Tree crown plays a crucial role in the process of photosynthesis and the formation of biomass. The site conditions and stand density have a significant impact on tree and crown growth, as well as biomass formation. Understanding crown growth and its influence on the allometric growth of the biomass of various organs under diverse site conditions and densities is critical to comprehending forest adaptation to climate change and management. This study examined the growth of trees, crown, and biomass in 36 plots of young Platycladus orientalis plantations across three site conditions (S1: thin soil on the sunny slope; S2: thick soil on the sunny slope; S3: thin soil on the shady slope) and four densities (D1: ≤1500 plants/hm2; D2: 1501–2000 plants/hm2; D3: 2001–3000 plants/hm2; and D4: ≥3001 plants/hm2). The findings of this study showed that S3 demonstrated the best tree growth, with considerably higher DBH and V than S1 and S2. In addition, as the number of trees grew, the average diameter at breast height (DBH), height (H), and volume (V) all decreased greatly. Poor site (S1) suppressed the canopy, decreasing crown width (CW), crown length (CL), crown ratio (CR), crown surface area (CCSA), and crown volume (CCV), while increasing crown efficiency (CEFF). This same trend was seen in D4, where CR, CCSA, and CCV were all much smaller than the other densities, but CEFF was the highest. Subjective and objective indicators were less responsive to changes in crown growth than crown composite indicators like CCSA, CCV, CEFF, and CR. Site condition and density had a major impact on biomass accumulation, with S1 and D4 having a much lower biomass than S2, S3, D1, D2, and D3. More biomass was allocated to the stem in S3 and D1, and more biomass was allocated to branches and leaves in S2, S3, D1, D2, and D3, resulting in a nearly isotropic growth of branches and leaves. The effect of crown indicators on the biomass of each organ varied according to site condition and density. In varied site conditions, crown and DBH ratio (RCD) contributed the most to stem biomass, whereas CL contributed the most to branch and root biomass. CL had the largest effect on biomass accumulation at various densities. This study demonstrates how site condition and density affect tree and crown development and biomass accumulation, providing theoretical guidance for plantation management under climate change.

Influence of stand and environmental factors on forest productivity of Platycladus orientalis plantations in Beijing’s mountainous areas

The purpose of forest management is to establish a forest ecosystem with multifunction in Beijing’s mountainous areas, and the priority is to increase forest productivity aiming to achieve carbon neutrality. In this study, we investigated 62 sample plots of Platycladus orientalis plantations and compared the relative contributions of stand and environmental factors to forest productivity by using variance partitioning analysis, the direct and indirect effects of these factors were explored by using structural equation model. And the geographical distribution of areas with higher forest productivity of Platycladus orientalis plantations was simulated and the contributions of these factors to the greater productivity was analyzed by using maximum entropy model (MaxEnt). The results indicated that topography was the dominant factors affecting the forest productivity of Platycladus orientalis plantations, followed by stand and soil nutrient factors. The results of structural equation model indicated that both topography and stand factors not only directly affect forest productivity, but also indirectly affect it by influencing soil nutrients. Soil nutrients had only direct impact on forest productivity. Forest productivity of Platycladus orientalis plantations was higher in areas with low altitude (168–252 m), gentle slopes (5–13 degrees), sunny slopes or semi-sunny slopes, soil total nitrogen content (>1.5 g/kg), and soil organic matter content (>38 g/kg). By changing the slopes to 5–13 degrees, increasing soil total nitrogen content to 1.5 g/kg and soil organic matter content to 38 g/kg, the average existence probability of higher forest productivity areas increased from 0.32 to 0.46, and amount of areas with higher productivity will be increased by approximately 43.8 %.

The Effect of Different Vegetation Restoration Types on Soil Quality in Mountainous Areas of Beijing

Soil quality is a very important indicator used to assess ecosystem restoration states in terms of vegetation recovery and establishment. Evaluating the soil quality of different vegetation restoration types in mountainous areas of Beijing and identifying their influencing factors would provide a scientific basis and be helpful for vegetation restoration in the future. Six vegetation types (or communities), including Platycladus orientalis (L.) Franco pure forest (POP), Pinus tabulaeformis Carr. pure forest (PTP), Platycladus orientalis–Pinus tabulaeformis mixed forest (PPM), Platycladus orientalis coniferous and broadleaved mixed forest (POCB), Pinus tabulaeformis coniferous and broadleaved mixed forest (PTCB), deciduous broadleaved mixed forest (DBMF), and one area of non-afforested land (NF), with similar stand conditions were selected and fourteen factors of soil physical and chemical characteristics were measured and used to establish a total data set (TDS), while a minimum data set (MDS) was obtained by using the principal component analysis (PCA) and Pearson correlation analysis methods. Two scoring methods, linear (L) and non-linear (NL), were used to calculate the soil quality index (SQI), and the key factors influencing soil quality by vegetation were identified by a general linear model (GLM), PCA, and correlation analysis. The results showed that: (1) The screened MDS indicators which showed good relationships with the SQIs in the study areas were total nitrogen (TN), sand content, total potassium (TK), pH, and available water capacity (AWC). The SQI–NLM method has better applicability. (2) The contribution rates of vegetation to different soil factors accounted for 28.644% (TN), 21.398% (sand content), 24.551% (TK), 16.075% (pH), and 9.332% (AWC). (3) TN showed a positive relationship with all vegetation types; the content of TN in PTCB and DBMF was obviously larger than in the other types in the 0–10 cm layer; PPM, PTCB, and POCB affected the sand content, which showed negative correlativity; and DBMF showed positive correlativity with AWC. The mechanism of how different species affect TN, sand content, and AWC should be focused on and taken into consideration in further studies.

Tree growth as an effect indicator of silvopastoral systems in the low hilly area of western Henan province, China

The low hilly area is a major landform in the west of Henan province, China, and it is suffering soil and water loss because of human activities. The silvopastoral system that combines trees and grasses has been widely used to restore this fragile area. We conducted in situ field experiments in 2011 in the low hilly area of Henan province involving pure forests of Populus simonii (PS; Salicaceae), Platycladus orientalis (PO; Cupressaceae), Quercusvariabilis (QV; Fagaceae), and Robinia pseudoacacia (RP; Fabaceae), and also with each forest tree species being combined with Medicago sativa (MS; Fabaceae) as silvopastoral systems, i.e., PS-MS, PO-MS, QV-MS, and RP-MS, respectively. We recorded tree diameter at breast height (DBH) and tree height (TH) in the years 2014–2016, 2018, 2020, and 2022 for all the different vegetation types. Tree biomass load (TBL, i.e., tree biomass per unit area) was estimated based on DBH and TH using allometric equations for each tree species. Generally, the results showed that the DBH, TH, and TBL were promoted in the silvopastoral systems PS-MS, PO-MS, and QV-MS. Specially, the DBH and TBL of PS-MS and PO-MS tended to be higher and were significantly higher than the pure forests of PS and MS, respectively, in 2014–2016; the silvopastoral systems were not significantly different from the pure forests for DBH in 2018 and 2022, and for TBL in 2018 and 2020. TH was lower in PS-MS and PO-MS than that in PS and PO in 2014–2016, while there was no difference of TH between PS-MS and PS in 2018 and 2022, and TH was higher in PO-MS than that in PO in 2018, 2020 and 2022. The DBH, TH, and TBL were all higher in QV-MS than QV. The TBL in RP-MS was non-significant or lower compared to that in RP. Moreover, TBL tended to be lower in upslope positions than downslope in the pure forests, while there was no difference in most silvopastoral systems. In summary, PS and PO may be suggested as the tree species selection in vegetation restoration processes for about five years, QV may be a better alternative for a long term, while RP is not recommended.

Water holding characteristics of litters of typical forest in loess area of Western Shanxi Province, China

It is of great significance to investigate the volume and water holding characteristics of litters for the accurate evaluation of forest water conservation function. With Pinus tabuliformis, Robinia pseudoacacia, Populus davidiana, Quercus wutaishanica and Platycladus orientalis as the research objects in the Loess Plateau of Western Shanxi Province, we analyzed the thickness of undecomposed layer and semi-decomposed layer, the volume of litter, and the relationship between the litter water-holding characteristics and the immersion time for different stands by the combination of sample survey and indoor immersion test. The results showed that the total thickness of litter layer was 4.06-5.12 cm, with the thickest layer in R. pseudoacacia forest and the thinnest in P. tabuliformis forest. The storage volume of litter was the largest in Q. wutaishanica (24.39 t·hm-2), followed by P. davidiana (23.64 t·hm-2), P. orientalis (22.51 t·hm-2), and R. pseudoacacia (22.48 t·hm-2), and the smallest in P. tabuliformis (20.42 t·hm-2). The volume in the undecomposed layer was less than that in the semi-decomposed layer. The maximum water holding of litter was 40.41-79.56 t·hm-2, with the highest of Q. wutaishanica and the lowest of P. tabuliformis. The effective interception rate of litter was 108%-188%. The changes of water capacity and water absorption rate of litter were most rapid in Q. wutaishanica, P. davidiana and R. pseudoacacia, and the changes were faster in the semi-decomposed layer than in the undecomposed layer. The water-holding capacity of litter in five forests was following an order of Q. wutaishanica>P. davidiana>R. pseudoacacia>P. orientalis>P. tabuliformis.

The three-dimensional distribution of bordered pits across growth rings of stem segment in Platycladus orientalis (Cupressaceae) seedlings

Summary The dimensions and distribution pattern of bordered pits are critical to the xylem water transport function of trees. However, studies on the three-dimensional distribution pattern of pits across xylem growth rings are still limited. Here, Micro-Computed Tomography (Micro-CT) was used to acquire xylem images of two-year-old Platycladus orientalis seedlings. We analyzed the tracheid lumen diameter of 665 tracheids, pit volume, and pit diameter of 11 810 inter-tracheid pits from three radial profiles. The volume ratio of inter-tracheid pits was about 0.90–0.96%. The average pit diameter was 6.8 μm and the average pit volume was 58.9 μm3, and more than 80% of the pits had a diameter of 5–8 μm and a volume of 20–90 μm3. Both the pit diameter and the pit volume increased gradually in the radial direction from the second-year growth ring to the current-year growth ring, and the pit diameter and volume were significantly higher in earlywood than in latewood. The distribution pattern of the tracheid diameter was similar to that of the pit diameter, and the wider the tracheids, the larger the pits. The distribution of bordered pits in P. orientalis may be a critical trait explaining the xylem embolism spread pattern in this species.

Toxicological studies of Thuja orientalis plant extract and Vertimec 1.8 EC against two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae) under laboratory conditions

Toxicological studies of Thuja orientalis plant extract and Vertimec 1.8 EC against two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae) under laboratory conditions

Contact Mechanics between Torus and Pit Border for Developing Air-Seeding Seal in Aspirated Bordered Pits

Bordered pits in conifers have been recognized as a significant evolutionary characteristic that served to impede the spread of embolisms between tracheids. Nevertheless, there was a lack of comprehensive understanding regarding the mechanical properties of the torus and the pit border in relation to the formation of contact seals in aspirated pits. A solid mechanics model was developed to study aspirated bordered pits, incorporating the elastic deformation of the torus–margo structure and the contact behavior between the torus and the pit border. Ten pit samples were reconstructed using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) pictures in order to develop mechanical models for pits in the stems of Platycladus orientalis. Due to the limited contact area on the torus surface, the contact pressure between the torus and the pit border exceeded the air pressure in aspirated bordered pits. The external force and the duration required to seal pits decreased when the pit diameter increased and the pit depth decreased. The augmentation of the torus and margo mass necessitated a lengthier duration for the closure of cavities. The findings presented in this study offered theoretical support for the capillary-seeding hypothesis. The aspiration in bordered pits mechanically depended on the structural and material characteristics of the torus and margo.

Estimation of bark water storage capacity of broad- and needle-leaved trees planted in a semi-arid climate zone

In forest ecosystems, measurement of bark water storage capacity (BWSC) is required for determining the amount of rainfall interception and understanding throughfall and stemflow processes. We compared the bark roughness coefficient (BRC) and BWSC of even-aged, widely-planted, broad-leaved and needle-leaved species in the Chitgar Forest Park, near Tehran, Iran. Bark samples (n = 10 per species) were extracted from three needle-leaved species (Cupressus arizonica, Thuja orientalis, and Pinus eldarica) and two broad-leaved species (Acer velutinum and Robinia pseudoacacia). The highest and lowest BWSC was found to be for A. velutinum and P. eldarica trees, respectively (0.63 vs. 0.32 g cm−3). Among the studied species, R. pseudoacacia had the highest BRC (0.69), and the lowest was found to be for A. velutinum species (0.03). The whole tree bole BWSC ranged from 156.8 L for P. eldarica to 14.6 L for A. velutinum. The results suggested that A. velutinum may provide more stemflow to the forest floor due to its small size, low BRC and subsequent low whole tree bole BWSC. These findings significantly contribute to our understanding of rainfall partitioning dynamics and ecohydrological processes associated with stemflow from trees. This improved understanding will help managers in selecting tree hydrologic characteristics that align with their objectives in forestry treatments, afforestation plans and establishment of vegetation in urban park settings within drylands.

Forest Fire Spread Hazard and Landscape Pattern Characteristics in the Mountainous District, Beijing

Objective: This study established an index system for assessing forest fire spread hazards and conducted a forest fire spread hazard assessment in the mountainous district of Beijing (including Fangshan, Mentougou, Changping, Yanqing, Huairou, Miyun, and Pinggu). The relationship between forested landscape spatial pattern and forest fire spread hazard was explored; this method provided the basis for the establishment of a landscape forest fire security guarantee system. Methods: The forest fire spread hazard assessment index system was constructed from four aspects: forest fuel, meteorological factors, topographic factors, and fire behavior. The weighted comprehensive evaluation method and area-weighted average method were used to calculate the forest fire spread hazard indices at the subcompartment scale and township scale. Moran’s I index was selected as the spatial autocorrelation index to analyze the autocorrelation degree and spatial distribution of the forest fire spread hazard index. Eleven representative landscape pattern indices were selected to analyze the main landscape spatial pattern affecting forest fire spread hazard by correlation analysis and principal component analysis. Results: (1) The areas with high, medium–high, medium-low, and low forest fire spread hazard grades accounted for 39.87%, 33.10%, 11.37%, and 15.66% of the study area, respectively, at the subcompartment scale and for 52.36%, 22.58%, 18.39%, and 6.67% of the study area, respectively, at the township scale. (2) The forest fire spread hazard index results obtained at the subcompartment and township scales in the Mountainous District of Beijing showed a spatial agglomeration distribution law. (3) The forest fire spread hazard was influenced mainly by landscape diversity (SHDI and PRD), landscape aggregation (AI, CONTAG, and PD), and landscape area (TA). Conclusions: The overall forest fire spread hazard in the mountainous district of Beijing showed a gradual increase from plains to mountainous areas. The land types of the high-spread hazard subcompartment mainly included general shrubbery and coniferous forestlands, and the dominant species in the high-spread hazard arbor forest subcompartment were mainly Platycladus orientalis, Pinus tabuliformis, and Quercus mongolica.