Broad-leaved Research Articles

Tree-Ring δ13C and Intrinsic Water-Use Efficiency Reveal Physiological Responses to Climate Change in Semi-Arid Areas of North China

Climate change has had a widespread and profound impact on global temperature and precipitation patterns, especially in semi-arid areas. Plant δ13C and iWUE indicate the trade-off between carbon uptake and water loss, which is pivotal for understanding plant responses to climate change. Information about the long-term responses of the physiological and ecological processes of different tree species to climate change is also required. To investigate the impact of different forest stand structures and site conditions on long-term growth and physiological processes of coniferous and broad-leaved trees in the mountainous area of Beijing, we analyzed the tree-ring δ13C variation of four tree species (Platycladus orientalis, Pinus tabuliformis, Quercus variabilis, Robinia pseudoacacia) sampled from 64 plots with varying site and stand conditions. We found that the tree-ring δ13C of the four tree species varied from each other and was mainly affected by density and slope aspect, followed by slope and age. Both tree-ring δ13C and iWUE of the four tree species showed increasing trends over time, mechanistically linked to long-term changes in global CO2 concentration. This indicates the four native tree species have adapted well to climate change, and the risk of decline is relatively low. The increased iWUE translated into different growth patterns which varied with tree species, site, and stand condition. Different tree species have varying sensitivities to environmental factors. The iWUE of coniferous tree species is more sensitive to climate change than that of broad-leaved tree species, especially to temperature (T), the Standardized Precipitation Evapotranspiration Index (SPEI), and vapor pressure deficit (VPD).

Coping with extremes: Responses of Quercus robur L. and Fagus sylvatica L. to soil drought and elevated vapour pressure deficit

Climate change, particularly droughts and heat waves, significantly impacts global photosynthesis and forest ecosystem sustainability. To understand how trees respond to and recover from hydrological stress, we investigated the combined effects of soil moisture and atmospheric vapour pressure deficit (VPD) on seedlings of the two major European broadleaved tree species Fagus sylvatica (FS) and Quercus robur (QR). The experiment was conducted under natural forest gap conditions, while soil water availability was strictly manipulated. We monitored gas exchange (net photosynthesis, stomatal conductance and transpiration rates), nonstructural carbohydrates (NSC) concentration in roots and stomatal morphometry (size and density) during a drought period and recovery. Our comparative empirical study allowed us to distinguish and quantify the effects of soil drought and VPD on stomatal behavior, going beyond theoretical models. We found that QR conserved water more conservatively than FS by reducing transpiration and regulating stomatal conductance under drought. FS maintained higher stomatal conductance and transpiration at elevated VPD until soil moisture became critically low. QR showed higher intrinsic water use efficiency than FS. Stomata density and size also likely played a role in photosynthetic rate and speed of recovery, especially since QR with its seasonal adjustments in stomatal traits (smaller, more numerous stomata in summer leaves) responded and recovered faster compared to FS. Our focal species showed different responses in NSC content under drought stress and recovery, suggesting possible different evolutionary pathways in coping with stress. QR mobilized soluble sugars, while FS relied on starch mobilization to resist drought. Although our focal species often co-occur in mixed forests, our study showed that they have evolved different physiological, morphological and biochemical strategies to cope with drought stress. This suggests that ongoing climate change may alter their competitive ability and adaptive potential in favor of one of the species studied.

Welcome to the forest theatre: Unveiling a Balkan refugium through paleoart

This paper presents an artistic paleolandscape experiment based primarily on recent palynological data from the Paleolithic site of Pešturina, in the Central Balkans of Serbia. These data are integrated into the general knowledge of flora and vegetation changes in the Balkans and southern Carpathians obtained through other paleobotanical sequences, especially pollen records from lake sediments. The paleoartistic proposal includes several drawing attempts at different geographic scales with an emphasis on plant taxa and their position within glacial refugia. The contrast with the interglacial situation is also illustrated, but the work especially focuses on the concept of long-term refugia and the altitudinal shifts of steppes, conifers, and broad-leaf trees. An ecological and biogeographical discussion accompanies the illustrations, highlighting the insurmountable methodological limitations and the challenges that pose obstacles to the progress of palynology as a technique for paleoenvironmental reconstruction at the spatial scale. The structure of the paper aims to serve as a guiding example for the teaching and scientific dissemination of paleosciences, from a conservationist perspective that is much needed in the current scenario of global change and biodiversity crisis.

Effects of stem size and age on resprouting ability of different tree species after clear-cutting in a warm temperate secondary forest

ABSTRACT Understanding the resprouting abilities of various tree species provides valuable insights into managing coppice forests and predicting forest dynamics. Clear-cutting was conducted in a secondary forest comprising warm-temperate broadleaf trees, and the stump size, age, and traits of the resprouts were measured to study their effects on resprouting ability. The number of resprouts that emerged from a stump was not significantly different when comparing different tree forms (canopy and shrub) or leaf longevity (evergreen and deciduous). Taller species generated taller and fast-growing resprouts. The ability to generate more resprouts with age was more important for species dominance than the ability to generate more resprouts with increase in stem size. Most shrub layer species exhibited age-related reductions in resprouting ability. Evergreen canopy species tended to have a larger number of resprouts and higher stump survival rate. The results suggest that the diversity of the resprouting traits among tree species could largely influence the stand dynamics and contribute to the coexistence of tree species.

Woodland in the Curonian spit during the 3rd millennium BC based on anthracological evidence from Neolithic sites

In this paper we present the first attempt to apply anthracological analysis in paleoenvironmental research in Lithuania. We present the results of charcoal analysis of three Neolithic archaeological sites in the Lithuanian part of the Curonian Spit. The formation and development of the Curonian Spit was a complex and dynamic process. Constant aeolian processes caused periods of sand deflation, which led to the movement of the dunes and drastic changes in the landscape until the 19th century when a protective dune ridge was built and systemic tree planting began. Curonian woodlands currently consist of mostly planted pine forests. Knowledge of the spit’s vegetation and its dynamics in prehistoric and historic periods is mainly based on palynological data. This study aims to gain a more detailed understanding of the composition and development of the Curonian Spit forests in the 3rd millennium BC. Anthracological analysis of charcoal samples from three sites located in the middle and northern parts of the spit show that broad-leaved tree species such as oak, maple and lime were spreading during the Neolithic and suggest that woodland vegetation in different parts of the spit was not uniform, with broad-leaved species thriving around Nida site and pine forests around Alksnynė. We propose that one of the reasons for the observed difference between the sites is the different phases of the spit formation that these sites underwent during the settlement period, as the middle part of the spit was formed earlier than the northern part and is therefore represented by less developed soils.

Quantification of tree growth change under climate change using National Forest Inventory of Korea

To achieve carbon neutrality in the face of climate change, accurately estimating forest carbon uptake is crucial. Environmental changes, such as temperature increases or precipitation fluctuations caused by climate change, can alter the growth responses of each species and act as a driver for changes in forest productivity. In particular, using a single-species growth model increases uncertainty in predicting stand growth, given the high species diversity in temperate forests in East Asia. Therefore, in this study, we identified the growth curve of 17 species-specific distributed in Korean temperate forest as well as the growth trend over the last 30 years (1976–2005). For this purpose, the species distribution and growth characteristics of 17 major Korean species of trees were analyzed using 13,808 tree-ring series from the 5th National Forest Inventory, which was conducted between 2006 and 2010. The growth characteristics of each species were analyzed using the average growth curve specific to each species, and the yearly growth trend was examined through residual analysis of the average growth curve. The distribution range of the 17 major tree species varied by species, as did the growth rate, ranging from 7 cm² · year⁻¹ to 17 cm² · year⁻¹ for the 30-year-old average basal area increment (BAI). Over time, fast-growing tree species exhibited initially high BAI, followed by a sharp decline from the 2000s. In contrast, broadleaf trees showed a continuous increase. Furthermore, a comparison of the total volume of individual trees and the volume of the yield table revealed that accurately estimating the actual forest volume was challenging. This study contributes to improving the accuracy of productivity predictions for temperate forests, underscoring the necessity to investigate the interaction between climate and forest succession in the future.

Hyperspectral and Weather Resistant Biomimetic Leaf Enabled by Interlayer Confinement

AbstractMimicking the characteristics and achieving specific functions of biological systems is stirring but challenging. Generally, pigments in the commercial coating can only achieve a similarity in chromaticity, while cannot obtain a similarity in the solar reflective spectrum whose difficulty resides in simulating spectral characteristics simultaneously. Unfortunately, traditional organic pigments show poor weather and heat resistance. Herein, with the little difference in the color difference (ΔEab*), the high spectral similarity, as well as adjustable green peak and similar red edge slope compared with the common plants (pagoda tree leaf, etc.) in 400–2500 nm, is also attained. It is achieved by the interlayer confined organic pigment in Mg/Al‐layered double hydroxide (Mg/Al‐LDH) layers. The corresponding biomimetic leaf displays high hyperspectral performance with a spectral angle cosine of 0.9922 and heat resistance at 120 °C. The longer weather resistance than that of mechanical mixing is also demonstrated. The intercalated chromophores of sodium copper chlorophyllin in the Mg/Al‐LDH and the interlayer confinement of Mg/Al‐LDH contribute to the excellent performance. This work provides a green pigment and a biomimetic leaf requiring the same chromaticity and spectrum as green plants, filling the long‐term use demand gap for heat and weather‐resistant biomimetic vegetation.

Carbon cycling through plant and fungal herbarium specimens tracks the Suess effect over more than a century of environmental change

Although the anthropogenic decline in atmospheric carbon stable isotope ratios (δ13C) over the last 150 years (termed the Suess effect) is well-studied, how different terrestrial trophic levels and modes reflect this decline remains unresolved. To evaluate the Suess effect as an opportunistic tracer of terrestrial forest carbon cycling, this study analyzed the δ13C in herbarium specimens collected in Minnesota, USA from 1877 to 2019. Our results suggest that both broadleaf trees and ectomycorrhizal fungi relied on recent photosynthate to produce leaves and sporocarps, while saprotrophic fungi on average used carbon fixed from the atmosphere 32–55 years ago for sporocarp construction. The δ13C values of saprotrophic fungal collections were also sensitive to the age of their plant carbon substrate, with sporocarps of twig specialists tracking changes in atmospheric δ13C more closely than saprotrophs growing on logs. Collectively, this study indicates that natural history collections can quantitatively track carbon cycling among plants and fungi over time.

Isolation, identification, biological characteristics, and pathogenicity of an entomogenous fungus against the Egyptian mealybug, Icerya aegyptiaca (J.) (Hemiptera: Monophlebidae)

BackgroundIn this study, an entomogenous, fungus was isolated from the Egyptian mealybug, Icerya aegyptiaca (J.) (Hemiptera: Monophlebidae) on the parasol leaf tree, Macaranga tanarius, in China where evaluated as a biocontrol fungus to reduce the population of the target insect. The strain was identified as Aspergillus parasiticus by morphological and phylogenetic analysisand named ZHKUAP1. The biological characteristics, pathogenicity, and field control effect of the strain were determined.ResultsThe most suitable medium for the mycelial growth of strain ZHKUAP1 was PPDA medium, with an optimum temperature of 30 °C and pH 7, in addition to glucose and peptone as carbon and nitrogen sources. The optimum sporulation conditions were the PPDA medium at 30 °C and pH 6, using the soluble starch and beef extract as carbon and nitrogen sources. The mycelial growth and spore production of strain ZHKUAP1 were stopped at 70 °C and above, indicating that it was not resistant to high temperatures. High concentrations of spore suspension, against young insect age, resulted high corrected mortality, as well as decreased the median lethal time. When the spore concentration was 1 × 108 cfu/ml, the corrected mortality of the second nymph was 88.33%, and the LT50 was 0.66 day. After 10 days of inoculation, the LC50 of the second instar nymph was the smallest, reaching 4.07 × 104 cfu/ml. On the 10th day of the field experiment, the corrected mortality was 76.45%, indicating that the A. parasiticus strain ZHKUAP1 had strong pathogenicity on I. aegyptiaca population.ConclusionsThe indoor toxicity of the strain to I. aegyptiaca was determined, and the field control effect of the pathogen was explored on this basis. The results have important application prospects in the biological control of I. aegyptiaca.

Single-nucleotide polymorphisms and copy number variations drive adaptive evolution to freezing stress in a subtropical evergreen broad-leaved tree: Hexaploid wild Camellia oleifera

Subtropical evergreen broad-leaved trees are usually vulnerable to freezing stress, while hexaploid wild Camellia oleifera shows strong freezing tolerance. As a valuable genetic resource of woody oil crop C. oleifera, wild C. oleifera can serve as a case for studying the molecular bases of adaptive evolution to freezing stress. Here, 47 wild C. oleifera from 11 natural distribution sites in China and 4 relative species of C. oleifera were selected for genome sequencing. “Min Temperature of Coldest Month” (BIO6) had the highest comprehensive contribution to wild C. oleifera distribution. The population genetic structure of wild C. oleifera could be divided into two groups: in cold winter (BIO6 ≤ 0 °C) and warm winter (BIO6 > 0 °C) areas. Wild C. oleifera in cold winter areas might have experienced stronger selection pressures and population bottlenecks with lower Ne than those in warm winter areas. 155 single-nucleotide polymorphisms (SNPs) were significantly correlated with the key bioclimatic variables (106 SNPs significantly correlated with BIO6). Twenty key SNPs and 15 key copy number variation regions (CNVRs) were found with genotype differentiation > 50% between the two groups of wild C. oleifera. Key SNPs in cis-regulatory elements might affect the expression of key genes associated with freezing tolerance, and they were also found within a CNVR suggesting interactions between them. Some key CNVRs in the exon regions were closely related to the differentially expressed genes under freezing stress. The findings suggest that rich SNPs and CNVRs in polyploid trees may contribute to the adaptive evolution to freezing stress.

Changes in plant-soil-microbe C-N-P contents and stoichiometry during poplar shelterbelt degradation

Extensive poplar shelterbelts are experiencing degradation, yet the consequences of this deterioration on plant-soil-microbe stoichiometry remain poorly understood. In this study, we selected three distinct types of pure poplar shelterbelts and examined the dynamics of tree leaf, soil, and microbial biomass carbon (C), nitrogen (N), and phosphorus (P) contents, as well as their stoichiometric relationships, at different stages of shelterbelt degradation, in order to explore the balance and limitation of nutrients in these rapidly degrading ecosystems. Our results show a consistent reduction in foliar N:P ratio throughout the degradation process for all shelterbelts, indicating an amplified N limitation on tree growth as degradation ensued. However, the underlying mechanisms varied among tree species. For Populus alba shelterbelts, the diminished soil organic carbon and total nitrogen (TN) contents during degradation suggest a reduction in the availability of substrates and energy sources for N mineralization, which combines with higher microbial N assimilation reflected by elevated soil microbial biomass carbon (SMBC) content, contributing to lower N absorption by trees. In Lombardy poplar shelterbelts, the inconsistent trends among reduced foliar N, stable soil TN, and unaltered SMBC and SMBC: SMBN ratio suggest either a decrease in microbial activity as degradation advanced or a reallocation of N by trees into tissues like roots, leaving the leaves N-deficient. Within Populus popular’s shelterbelts, the diminished foliar N content, accompanied by an augmented foliar C:N ratio and reduced soil N:P ratio, indicates potentially deteriorated litter quality. This deterioration contributes to knock-on effects involving N-deficit soil organic matter, limited soil N availability, decreased N absorption by trees, and subsequently reduced foliar N content. Our study highlights the distinctive responses of plant-soil-microbe C-N-P stoichiometry to shelterbelt degradation, contingent on tree species, underscoring the diverse strategies that poplar shelterbelts employ when confronted with harsh internal and external conditions.

Aboveground biomass and structural characteristics of poisonous Pieris japonica shrub stands dominating under deer pressure

ABSTRACT Canopy tree seedlings rarely grow in regions with overabundant deer in Japan, whereas Pieris japonica, a shrub species that is unpalatable to deer, has been expanding its habitat and occasionally forms dense pure stands in disturbed locations. Although this species could be the key to understanding vegetation structure and function under intense deer pressure, little information is available regarding the structural and functional aspects of P. japonica stands. Here, we examined aboveground mass (M A) and several structural parameters for 13 P. japonica stands of various developmental stages (3–64 years old as estimated from the number of growth rings of component plants); the stand M A and leaf area were estimated by developing relevant allometric equations for individual plants. The M A of P. japonica stands (≤50 Mg ha−1) were less than a fifth of that recorded for neighboring forests consisting of deciduous broad-leaved trees and conifers. Leaf area index (≤4.9 m2 m−2) and basal stem area (≤62 m2 ha−1, determined at 5 cm from the ground) of the stands reached the level comparable to tree forests, whereas canopy height (≤4.4 m) was much shorter and plant density (≥7,300 stems ha−1) was fairly high compared with those of average tree forests in neighboring regions. The stand structure lacked thick and long boles, resulting in low biomass accumulation in P. japonica stands. Thus, one possible consequence of the long-lasting deer pressure is the reduction of the carbon sequestration capacity to a fraction of that of the present forests.

Effects of Human Harvesting, Residences, and Forage Abundance on Deer Spatial Distribution.

It has been known that harvesting by humans strongly influences individual within-home range habitat selection of many deer species; however, little is known about the effect of harvesting on coarse-scale habitat selection (i.e., spatial distribution). We examined the summer spatial distribution of sika deer Cervus nippon in relation to human harvesting and other factors, such as human residences, forage abundance, and cover, using pellet group counts at Mount Fuji, central Japan, in 2018. In the study area, harvesting is conducted at medium elevation areas throughout the year, but not at high or low elevation areas where access is difficult or harvesting is prohibited. Spatial distribution of deer was significantly biased to non-harvesting areas and far from residential areas, suggesting that they avoid riskier spaces by establishing a landscape of fear. High-quality food resources (deciduous broad-leaved trees and forbs) were more abundant in harvesting areas than in non-harvesting areas, suggesting that foraging pressure by deer reduce them. However, there were no differences in abundances of more fibrous dwarf bamboo between harvesting and non-harvesting areas, and spatial distribution of deer was significantly biased to higher dwarf bamboo abundance areas, suggesting that the dwarf bamboo is an alternative food resource in non-harvesting areas where supplies of high-quality food were limited. Our results suggest that human harvesting pressure and residences shifted the spatial distribution of deer from the montane forests to subalpine/alpine zones, which may increase damage to vulnerable ecosystems due to severe foraging pressure.

Impact of irrigation intervals with fertigation timing on Washington navel orange tree productivity and leaf nutrient content.

Impact of irrigation intervals with fertigation timing on Washington navel orange tree productivity and leaf nutrient content.

Exploring the Holocene rise, disturbance and decline of pine forests in the river valleys of northeastern Belgium using pollen and botanical macroremains

The Holocene evolution of vegetation and environment in the Kleine Nete valley in the coversand region of northeastern Belgium is studied through sedimentological, palynological and macrobotanical analysis of a radiocarbon dated peat sequence. Peat formation started at the beginning of the Holocene in mesotrophic fen conditions. After a period of fast peat growth, the accumulation slowed down and the peat surface became dry in the Middle Holocene.The palynological results are compared with other pollen data from the region, in order to establish a regional pollen biozonation for the Early and Middle Holocene in the Nete Basin. This shows that pine has long been a characteristic element in the Nete Basin. Pine forest expanded immediately after the 11.4 cold event, which is earlier than in the western Scheldt Basin. Pine and birch grew along the valley, possibly also within the peatland. Peaks of microcharcoal, herbs and/or coarse sediment in the peat reflect temporary local forest disturbances in the Early Holocene. Some may reflect small-scale controlled fires induced by hunter-gatherers, although a natural cause seems much more plausible given the dominance of fire-associated pines and increased drought. Pine remained important throughout the Early Holocene. This long-lasting predominance of pine in the Nete Basin, compared to elsewhere in the Scheldt Basin, is likely related to the poor sandy subsoil in the region, which hinders more nutrient-demanding broadleaf trees to overtake.

Contrasting effects of urban trees on air quality: From the aerodynamic effects in streets to impacts of biogenic emissions in cities

Urban trees are often not considered in air-quality models although they can significantly impact the concentrations of pollutants. Gas and particles can deposit on leaf surfaces, lowering their concentrations, but the tree crown aerodynamic effect is antagonist, limiting the dispersion of pollutants in streets. Furthermore, trees emit Biogenic Volatile Organic Compounds (BVOCs) that react with other compounds to form ozone and secondary organic aerosols. This study aims to quantify the impacts of these three tree effects (dry deposition, aerodynamic effect and BVOC emissions) on air quality from the regional to the street scale over Paris city. Each tree effect is added in the model chain CHIMERE/MUNICH/SSH-aerosol. The tree location and characteristics are determined using the Paris tree inventory, combined with allometric equations. The air-quality simulations are performed over June and July 2022. The results show that the aerodynamic tree effect increases the concentrations of gas and particles emitted in streets, such as NOx (+4.6 % on average in streets with trees and up to +37 % for NO2). This effect increases with the tree Leaf Area Index and it is more important in streets with high traffic, suggesting to limit the planting of trees with large crowns on high-traffic streets. The effect of dry deposition of gas and particles on leaves is very limited, reducing the concentrations of O3 concentrations by −0.6 % on average and at most −2.5 %. Tree biogenic emissions largely increase the isoprene and monoterpene concentrations, bringing the simulated concentrations closer to observations. Over the two-week sensitivity analysis, biogenic emissions induce an increase of O3, organic particles and PM2.5 street concentrations by respectively +1.1, +2.4 and + 0.5 % on average over all streets. This concentration increase may reach locally +3.5, +12.3 and + 2.9 % respectively for O3, organic particles and PM2.5, suggesting to prefer the plantation of low-emitting VOC species in cities.

Chronic rockfall in abandoned quarry: Chronology, modelling and implications

Abandoned quarries are a relatively common form of anthropogenic relief. The rocks disturbed by previous mining activities could foster conditions favourable for future dynamic geomorphic processes on quarry faces. Nevertheless, the activity of such processes, particularly that of rockfall, has not yet been studied in detail. This is of particular importance because human infrastructure is often still present in abandoned quarries, and rockfall can cause distinct natural hazards in such conditions. This study focuses on a multidisciplinary analysis of rockfall in selected abandoned quarry in the region of the Carpathians. A dendrogeomorphic analysis of 807 tree-ring series from 130 disturbed trees occupying the talus provided evidence of 264 tree injuries caused by falling rocks during the last 22 years. The reconstructed frequency of rockfall in quarries is several times higher than that of rockfall from natural localities within the studied region but also in Europe. Next, the seasonal dating of rockfall hits to trees displayed the prominence of such events during the tree dormancy period (ca. October to April), suggesting freeze–thaw cycles as the main trigger (the same as for natural localities in the region). Three species of broad-leaved trees of comparable age were used for the reconstruction, but no differences among the species were detected. The number of rockfall hits on tree trunks decreased significantly with increasing distance from the rockfall source zone, suggesting strong gradation of rockfall activity, compared to natural localities. Generally, the multidisciplinary results suggest very unstable conditions of rocks in abandoned quarries, predisposing them to frequent gravitational events. In contrast, ecological succession after mining termination gradually offers a protective function of trees.

New Intrinsic Ecological Mechanisms of Leaf Nutrient Resorption in Temperate Deciduous Trees.

Leaf nutrient resorption is a critical process in plant nutrient conservation during leaf senescence. However, the ecological mechanisms underlying the large variability in nitrogen (NRE) and phosphorous (PRE) resorption efficiencies among trees remain poorly understood. We conducted a comprehensive study on NRE and PRE variability using 61 tree individuals of 10 temperate broad-leaved tree species. Three potentially interrelated intrinsic ecological mechanisms (i.e., leaf senescence phenology, leaf pigments, and energy residual) were verified. We found that a delayed leaf senescence date, increased degradation of chlorophylls and carotenoids, biosynthesis of anthocyanins, and reduced nonstructural carbohydrates were all positively correlated with NRE and PRE at the individual tree level. The intrinsic factors affecting resorption efficiency were ranked in decreasing order of importance: leaf pigments > energy residual > senescence phenology. These factors explained more variability in NRE than in PRE. Our findings highlight the significance of these three ecological mechanisms in leaf nutrient resorption and have important implications for understanding how nutrient resorption responds to climate change.

Predicting the Potential Distribution of Quercus oxyphylla in China under Climate Change Scenarios

Global climate changes are expected to profoundly shape species distribution. Quercus oxyphylla, a valuable evergreen broad-leaved tree species, is rigorously conserved and managed in China owing to its substantial scientific, economic, and ecological value. However, the impact of projected climate change on its future distribution and potential climatic drivers remains unclear. Here, a maximum entropy model (MaxEnt) was used to explore the distribution of Q. oxyphylla in China under current conditions and three future scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) for the 2050s and 2070s. We optimized the model using the ‘ENMeval’ package to obtain the best parameter combination (RM = 1, FC = LQHPT), and multiple evaluation metrics (AUC ≥ 0.9; TSS ≥ 0.6; Kappa ≥ 0.75) verified the high accuracy of the model and the reliability of the prediction results. We found the following: (1) The potential distribution of Q. oxyphylla spans across 28 provinces in China under current climatic conditions, predominantly in southern regions, with Sichuan exhibiting the largest suitable area for survival. The total suitable habitat covers 244.98 × 104 km2, comprising highly, moderately, and poorly suitable habitats of 51.66 × 104 km2, 65.98 × 104 km2, and 127.34 × 104 km2, respectively. (2) Under future climate conditions, the overall geographical boundaries of Q. oxyphylla are predicted to remain similar to the present one, with an increase of 10.29% in the 2050s and 11.31% in the 2070s. In the 2050s, the total suitable habitats for Q. oxyphylla under the three scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) might increase by 8.83%, 9.62%, and 12.42%, while in the 2070s they might increase by 10.39%, 17.21%, and 6.33%, respectively. (3) Moreover, the centroid of the suitable area is expected to migrate southwestward under the three scenarios in the future. (4) Annual precipitation, isothermality, and temperature annual range emerged as the main factors influencing the distribution of Q. oxyphylla, with contributions of 55.9%, 25.7%, and 13.5%, respectively. Our findings refined the spatial arrangement of Q. oxyphylla growth and revealed its climate resilience. This suggested that under climate change, Sichuan and Shaanxi are the optimal regions for cultivation and management, while appropriate conservation strategies should be formulated in Tibet and Hubei.

Comparison of biogenic volatile organic compounds emissions from representative urban tree species in South Korea and evaluation of standard emission rate models

Although trees generally help alleviate global warming, they generate biogenic volatile organic compounds (BVOCs) that may contribute to air pollution and exacerbate climate change. To estimate BVOCs emission rates, several models have been widely used to calculate the standard emission rate (ERs) that takes temperature and light intensity into account. In this study, the effects of temperature and light intensity on the isoprene and monoterpene emissions from various tree species were investigated. Four broad-leaved trees (Platanus occidentalis, Quercus mongolica, Zelkova serrata, and Acer palmatum) and three coniferous trees (Pinus densiflora, Metasequoia glyptostroboides, and Pinus koraiensis) were investigated in August 2022 for the comparison by the species. Emissions from Pinus densiflora were also measured in May for comparison with different climate conditions. Platanus occidentalis revealed the highest emission of isoprene, followed by Quercus mongolica, Zelkova serrata, and Acer palmatum. It was found that the isoprene emissions from Zelkova serrata and Quercus mongolica had a stronger correlation with light intensity than those from Platanus occidentalis. In contrast, the isoprene emissions from Platanus occidentalis exhibited the strongest correlation with temperature compared to other trees concerned. The monoterpene emission from Metasequoia glyptostroboides showed the highest correlation with light intensity (r2 = 0.662). Among the monoterpenes, α-pinene was the most affected by light intensity. Pinus densiflora was affected more by light intensity in May. The ERs estimation using the G93 model confirmed this pattern. Therefore, this study suggests that both light and temperature be taken into account in order to obtain more reliable ERs data of monoterpenes.