Search Results (35)

The fragile ancient ‘Shuikoulin’ forests, which provide critical habitats for the critically endangered Blue-crowned Laughingthrush, are increasingly degraded by soil contamination and heavy metal pollution. This study examines the rhizosphere environment of four key ancient tree species in the bird’s core habitat, focusing on soil properties, heavy metal accumulation, and the structure of arbuscular mycorrhizal (AM) fungal communities. The results revealed that Liquidambar formosana showed the highest total nitrogen (TN) and available phosphorus (AP), whereas Quercus chenii had the lowest soil organic matter (SOM). The primary heavy metal contaminant across all tree species was Cd (Igeo > 2), followed by the metalloid As. We detected 41 AM fungal species spanning 7 genera, with Glomus dominating (84.19% relative abundance). OTU richness was highest in Cinnamomum camphora and L. formosana (110 each), followed by Q. chenii (88) and Castanopsis sclerophylla (75). Structural equation modeling indicated that soil nutrients (TN, TP, AP, SOM) suppressed the accumulation of V, Cr, Ni, and Cu, thereby indirectly favoring Glomus and Paraglomus. In contrast, higher pH and total potassium (TK) levels promoted Co and Zn bioavailability and negatively affected Acaulospora and other minor genera. Tree species identity directly modulated these interactions. Our findings demonstrate that ancient tree species shape AM fungal assembly through distinct rhizosphere geochemical niches, providing a mechanistic basis for restoring degraded habitats critical to endangered species conservation. Full article

This study established a novel detection method for volatile organic compounds in forest therapy tree species based on direct thermal desorption technology. The optimized parameters included 20 mg sample loading, 110 °C desorption temperature, 30 min desorption time, and 1:30 split ratio. The optimal loading was 5–65 mg to balance the separation resolution and detection sensitivity. Desorption temperature significantly affected component detection: terpenoids accounted for the highest proportion (82.0%) at 90 °C; alkanes surged to 53.3% at 150 °C; acids (19.0%) and esters (19.4%) became dominant; and ascorbyl dipalmitate (17.3%) exceeded linalool (14.6%) at 180 °C. Chemotype analysis revealed that camphor-type leaves were dominated by camphor (72.8%) while linalool-type leaves by linalool (54.3%). Compared with steam distillation, DTD increased the camphor/linalool extraction efficiency while eliminating solvent contamination. Relative to dynamic headspace sampling, DTD mitigated the environmental interference and reduced the pretreatment time. The study confirmed that 110 °C is the optimal temperature for maximized characterization of terpenoids (63.3%), providing technical support for selecting high-terpenoid-emitting trees in forest therapy and evaluating the therapeutic efficacy. It also reveals the linkages between leaf volatiles and stand-level air composition and promotes the development of dynamic forest VOC databases. Full article

Acid deposition, a major environmental issue causing soil acidification and microbial suppression, impacts forest nutrient cycling. Meanwhile, nitrogen (N) fertilization is widely applied in subtropical forests, yet its interaction with acid deposition on litter decomposition is unclear. We conducted a field experiment using two common tree species, Cunninghamia lanceolata and Cinnamomum camphora, and applied three acid deposition levels (0, 0.25, and 0.50 g H⁺ m⁻² month⁻¹) and four N fertilization levels (0, 3, 6, and 9 g N m⁻² year⁻¹) in a factorial design. Our results showed that acid deposition alone significantly reduced litter decomposition rates, with maximum mass loss decreasing by 23.6% for Cunninghamia and 36.3% for Cinnamomum (p < 0.05). Urea fertilization alone also suppressed decomposition, reducing maximum mass loss by 27.3% for Cunninghamia and 37.3% for Cinnamomum (p < 0.05). However, when combined, urea fertilization mitigated the suppressive effect of acid deposition, particularly under severe acid conditions, where maximum mass loss increased by 18.5% for Cunninghamia and 43.1% for Cinnamomum (p < 0.05). Acid deposition reduced microbial respiration and enzyme activities related to carbon cycling, while urea fertilization showed both positive and negative effects depending on the acid levels (p < 0.05). Urea can enhance the litter layer’s acid-buffering capacity, offering potential management insights for acid deposition-affected forests. Further research on microbial mechanisms across ecosystems is recommended. Full article

Urban forests play important roles in carbon sequestration and climate change mitigation. However, their adaptive mechanisms and limitations on photosynthesis throughout the canopy are poorly understood. This study takes the most widely distributed 50-year-old camphor plantations (Cinnamomum camphora) in Shanghai as the research objects. We investigated the variations in leaf morphology and photosynthetic physiology and biochemistry at six different canopy positions during a summer and an autumn period. We discovered that on account of leaf nitrogen loss and water deficit, light-saturated photosynthesis (A_max) declined in upper sunlit leaves despite being exposed to high sunlight in the same fashion as stomatal and mesophyll conductance (g_sw, g_m), photochemical quenching coefficient and actual photochemical efficiency of PSII (Φ_PSII, q_P), and maximum rate of electron transport and carboxylation (J_max, V_cmax) during the growing season. Although seasonal change had little effect on A_max, the relative importance of limitations varied temporally. Mesophyll and biochemical limitation were the major contributors to the decline in the A_max in upper sunlit leaves between summer and autumn, respectively. Our study highlights the constraints of carbon fixation capacity in dense stands of mature camphor trees and offers technical support for the accurate prediction of canopy photosynthesis and the enhancement of carbon sequestration management in urban forests. Full article

Forest resource surveys are of vital importance for grasping the current status of forest resources, formulating management strategies, and evaluating ecosystem functions. Traditional manual measurement methods have numerous limitations in complex forest environments. The emergence of LiDAR technology has provided a new approach. Backpack LiDAR has been increasingly applied due to its portability and flexibility. However, there is a lack of comprehensive research on the influence of different scanning routes on data quality and analysis results. In this study, forest plots of four tree species, namely Carya cathayensis, Cinnamomum camphora, Koelreuteria bipinnata, and Quercus acutissima in Chuzhou City, Anhui Province, were selected as the research objects. Six scanning routes were designed to collect point cloud data using backpack LiDAR. After preprocessing, including denoising and ground point classification, diameter at breast height (DBH) fitting and accuracy evaluation were carried out. The results indicated that the individual tree recognition rates of C. cathayensis, C. camphora, and K. bipinnata reached 100%, while that of Q. acutissima was between 64.71% and 78.07% and was significantly affected by the scanning route. The DBH fitting accuracy of each tree species varied among different routes. For example, C. cathayensis had high accuracy in routes 1 and 6, and C. camphora had high accuracy in routes 1 and 3. Tree species characteristics, scanning routes, and data processing methods jointly affected the DBH fitting accuracy. This study provides a basis for the application of backpack LiDAR in forest resource surveys. Although backpack LiDAR has advantages, it is still necessary to optimize data acquisition schemes targeting tree species characteristics and improve point cloud data processing algorithms to promote its in-depth application in the forestry field. Full article

Under global climate change, fragmented urban vegetation is more susceptible to the external environment, and changes in vegetation phenology are one of the most apparent responses. In this study, phenological camera (phenocamera) photo data, Klosterman curve fitting, and a Gu model were employed to explore the phenological characteristics of an urban forest at different levels within different species. Differences between species and groups regarding the upturn date (UD), the stabilization date (SD), the downturn date (DD), the recession date (RD), and the length of the growing season (LOS) are displayed in detail. We found that the UD of Cinnamomum camphora groups began in late April (day of year 108th), the SD appeared in early May (121st), and the DD started in early October (283rd) and ended in late October (293rd), with an average LOS of 185 days. The phenological characteristics of the Cinnamomum camphora and Bischofia polycarpa groups differed significantly. The average LOS of Bischofia polycarpa was 47 days longer than that of Cinnamomum camphora. Between Cinnamomum camphora individuals and group levels, differences in the UD and the SD were not obvious, while differences in the DD, the RD, and the LOS were large (LOS > RD > DD). The LOS of Cinnamomum camphora was longer on the individual scale (209 days), while the average LOS on the group scale was 185 days. In conclusion, our results reflect the more refined quantitative results of urban vegetation phenology and will help to elucidate urban vegetation phenological changes, which has important theoretical and practical significance for future urban forest management practices. Full article

Fine roots (diameter ≤ 2 mm) play a critical role in regulating soil organic carbon storage and nutrient cycling in forest ecosystems. However, the variability in fine root biomass, production, and turnover rates across different forest types remains poorly understood. This study investigates fine root dynamics, including biomass, distribution, and turnover, across four major monoculture plantation forests in subtropical China: Chinese fir (Cunninghamia lanceolata (Lamb.) Hook), Masson pine (Pinus massoniana Lamb.), Chinese sweet gum (Liquidambar formosana Hance), and camphor tree (Cinnamomum camphora (L.) J. Presl). Using a sequential coring method, soil samples were collected monthly to monitor live and dead fine root biomass across different soil depths (0–15 cm, 15–30 cm, 30–45 cm, and 45–60 cm). Fine root production and turnover rates were estimated using three methods: Max–Min, Integral and Decision Matrix. The results showed that fine root biomass was highest in the camphor tree forest (1.96 t ha⁻¹), followed by Masson pine (1.12 t ha⁻¹), Chinese fir (0.89 t ha⁻¹), and Chinese sweet gum (0.83 t ha⁻¹). Approximately 90% of the total fine root biomass was composed of live roots across all forest types, highlighting their significant role in nutrient uptake. Both live and dead fine roots were predominantly concentrated in the upper 0–30 cm soil layer, with a notable decline in biomass in deeper layers. Fine root biomass production was highest in the camphor tree forest (2.66–2.90 t ha⁻¹ a⁻¹), followed by Masson pine (1.16–1.83 t ha⁻¹ a⁻¹), Chinese fir (0.87–0.97 t ha⁻¹ a⁻¹), and Chinese sweet gum (0.87–0.93 t ha⁻¹ a⁻¹). Turnover rates were highest in the camphor tree forest (1.25–1.36 a⁻¹), followed by Masson pine (0.96–1.51 a⁻¹), and both Chinese fir and Chinese sweet gum (0.94–1.05 a⁻¹ and 0.97–1.04 a⁻¹, respectively). This study identifies significant differences in fine root dynamics among subtropical forest types, providing baseline data critical for optimizing forest management, particularly in urban and peri-urban areas. These insights can enhance reforestation efforts, ecosystem resilience, and sustainable forest productivity. Full article

Arbuscular mycorrhizal fungi (AMF) can preferentially absorb the released ammonium (NH₄⁺) over nitrate (NO₃⁻) during litter decomposition. However, the impact of AMF’s absorption of NH₄⁺ on litter nitrogen (N) decomposition is still unclear. In this study, we investigated the effects of AMF uptake for NH₄⁺ on litter N metabolic characteristics by enriching NH₄⁺ via AMF suppression and nitrification inhibition in a subtropical Cinnamomum camphora forest. The results showed that AMF suppression and nitrification inhibition significantly decelerated litter decomposition in the early stage due to the repression of NH₄⁺ in extracellular enzyme activity. In the late stage, when soil NH₄⁺ content was low, in contrast, they promoted litter decomposition by increasing the extracellular enzyme activities. Nitrification inhibition mainly promoted the utilization of plant-derived N by promoting the degradation of the amide I, amide II, and III bands by increasing protease activity, and it promoted ammonification by increasing urease activities, whereas it reduced the utilization of microbial-derived N by decreasing chitinase activity. On the contrary, AMF suppression, which significantly reduced the ammonification rate and increased the nitrification rate, only facilitated the degradation of the amide II band. Moreover, it intensified the microbial-derived N decomposition by increasing chitinase activity. The degradation of the amide I and II bands still relied on the priming effects of AMF on soil saprotrophs. This was likely driven by AMF-mediated phosphorus (P) mineralization. Nutrient acquiring, especially P by phosphatase, were the main factors in predicting litter decomposition and protein degradation. Thus, AMF could relieve the end-product repression of locally enriched NH₄⁺ in extracellular enzyme activity and promote early-stage litter decomposition. However, the promotive effects of AMF on litter protein degradation and NH₄⁺ release rely on P mineralization. Our results demonstrated that AMF could alleviate the N limitation for net primary production via accelerating litter N decomposition and reducing N loss. Moreover, they could restrict the decomposition of recalcitrant components by competing with saprotrophs for nutrients. Both pathways will contribute to C sequestration in forest ecosystems, which advances our understanding of AMF’s contribution to nutrient cycling and ecosystem processes in subtropical forests. Full article

Due to the frequent occurrence of forest fires worldwide, which cause severe economic losses and casualties, it is essential to explore the mechanisms of forest fires. In this study, seven common broadleaf plant species from southern China were selected to observe their microscopic structural parameters. The combustion performance parameters of the leaves of these seven species were measured using a cone calorimeter, and the relationship between the microscopic structure and combustion performance was analyzed. Additionally, factor analysis was used to study the combustion intensity factor (F1), fire resistance intensity factor (F2), and the comprehensive fire risk degree (F) of the leaves of the seven plant species. Finally, regression analysis was performed between the microscopic structural parameters and the comprehensive fire risk factor. The results show the following: (1) The ratio of spongy mesophyll to palisade cells (S/P) affects the combustion performance of plant leaves. (2) The ranking of the comprehensive fire risk factor for the leaves of the seven plant species is as follows: Osmanthus fragrans var. semperflorens (OFS) > Cinnamomum camphora (CC) > Loropetalum chinense (R. Br.) Oliv. (LC) > Pterocarya stenoptera C. DC. (PS) > Loropetalum chinense var. rubrum (LCVR) > Photinia beauverdiana C. K Schneid. (PB) > Styphnolobium japonicum (L.) Schott (SJ). (3) There is a strong exponential relationship between the comprehensive fire risk factor and the microscopic structural parameters. This study is beneficial for selecting fire-resistant tree species and monitoring species with higher comprehensive fire risk. Full article

Insect foliar herbivory is ubiquitous in terrestrial ecosystems, yet its impacts on soil nitrogen cycling processes remain not yet well known. To examine the impacts of insect foliar herbivory on soil N₂O emission flux and available nitrogen (N), we conducted a pot experiment to measure soil available N content and soil N₂O emission flux among three treatments (i.e., leaf herbivory, artificial defoliation, and control,) in two broad-leaved trees (Cinnamomum camphora and Liquidambar formosana) and two conifer trees (Pinus massonianna and Cryptomeria fortunei). Our results showed that insect foliar herbivory significantly increased soil inorganic N (i.e., NH₄⁺–N and NO₃⁻–N), dissolved organic nitrogen (DON) and microbial biomass nitrogen (MBN) contents, and urease activity compared to control treatment. However, there were no differences in soil available N contents and urease activity between artificial defoliation and control treatments, implying that insect foliar herbivory had greater impacts on soil available N contents compared to physical damage of leaves. Moreover, soil N₂O emission fluxes were increased by insect foliar herbivory in Cinnamomum camphora and Pinus massonianna, but not for the other two tree species, indicating various effect of insect foliar herbivory on soil N₂O emission among tree species. Furthermore, our results showed the positive correlations between soil N₂O emission flux and soil NO₃⁻–N, DON, MBN, and acid protease activity, and soil inorganic N, pH, and MBN mainly explained soil N₂O emission. Our results implied that insect foliar herbivory can speed up soil nitrogen availability in subtropical forests, but the impacts on soil N₂O emission are related to tree species. Full article

Mixed stands of tree species with complementary traits can modulate stand growth and timber quality. At the Fengshushan Forest Farm, mixtures of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) with Liquidambar formosana Hance, Schima superba Gardner & Champ., Elaeocarpus sylvestris (Lour.) Poir., Cinnamomum camphora (L.) Presl, and Chinese fir monoculture were established. Differences in stand growth and timber quality among these mixtures were assessed and a test was conducted to evaluate the factors influencing the mixture effects. The average diameter at breast height, tree height, stand volume, and individual tree annual increment of mixtures generally exceeded those of Chinese fir monocultures but not necessarily those of broad-leaved monocultures. When the net interaction between species was complementary, overyielding in mixtures occurred (RP_fir,bl > 0), which was influenced significantly by stand density, soil properties, and timber quality. The timber quality and wood production of Chinese fir were enhanced by mixture with some broad-leaved species, with reduced slenderness and knottiness in mixtures, and notable increases in medium- (average outturn rates of 56.13%) and large-diameter (11.71%) timber in C. lanceolata/C. camphora mixture. The growth and timber quality of Chinese fir are largely promoted when grown mixed with broad-leaved species. Overyielding at the stand level occurs where Chinese fir compensates for the underperformance of broad-leaved trees. Full article

In the global ecosystem, the slow decomposition of coniferous forest litter has caused a number of ecological problems, among which is the decay of China’s Pinus massoniana litter. It has been pointed out that converting pure P. massoniana plantations into mixed forests with broadleaf species can improve ecosystem services. Therefore, the selection of mixed species is key for the success or failure of the conversion of near-natural forests. In this study, from the perspective of apoplastic decomposition, the leaf litter of P. massoniana was mixed with three common native broadleaf species, namely Choerospondias axillaries, Cinnamomum camphora, and Cyclobalanopsis glauca, using an indoor incubation method to systematically analyse the differences in the decomposition rates of apoplastic material in each mixture, and to provide a theoretical basis for the selection and mixing of tree species for the management of near-natural forests in P. massoniana forests. After 175 days of indoor incubation of the foliar litter under dark conditions at 25 °C, the residual dry matter of the mixed apoplastic litter of P. massoniana and the three broadleaf trees was lower than that of P. massoniana. It indicated that the incorporation of broadleaf apoplastic foliage promoted litter decomposition, with the most pronounced effect in the case of admixture with C. Camphora. Compared with the group of pure P. massoniana alone, the remaining mass and residual rate decreased by 0.56 g and 9.45%, respectively. The regression equation of Olson’s negative exponential decay model showed that the P. massoniana + C. Camphora mixture had the fastest decomposition rate (k) of 1.305, an increase of 0.237, a decrease in half-life of 0.11 years, and a decrease in turnover period of 0.49 year, compared to the P. massoniana alone group. Most of the measured values throughout the incubation period were significantly lower than the predicted values, suggesting that there was a non-additive and synergistic effect of litter mixing. Full article

N⁶-methyladenosine (m⁶A) is one of the most abundant chemical modifications on mRNA in eukaryotes. RNA-binding proteins containing the YT521-B (YTH) domain play crucial roles in post-transcriptional regulation of plant growth, development, and stress response by reading the m⁶A mark. However, the YTH domain-containing RNA-binding protein family has not been studied in a valuable and medicinal tree such as Cinnamomum camphora (C. camphora) yet. In this study, we identified 10 YTH genes in C. camphora, located on eight out of 12 chromosomes. Phylogenetic analysis revealed that these genes can be classified into two major classes, YTHDF (CcDF) and YTHDC (CcDC). Closely related CcYTHs within the same class exhibited a similar distribution of conserved motifs and domain organization, suggesting functional similarities among these closely related CcYTHs. All CcYTH proteins possessed a highly conserved YTH domain, with CcDC1A containing an additional CCCH domain. The liquid–liquid phase separation (LLPS) predictions indicate that CcDC1A, CcDF1A, CcDF1C, CcDF3C, CcDF4C, and CcDF5C may undergo phase transitions. Quantitative expression analysis revealed that tissue-specific expression was observed fo CcYTHs. Notably, there were two genes, CcDF1A and CcDF5C; both exhibited significantly higher expression levels in various tissues than other genes, indicating that the m⁶A-YTH regulatory network in C. camphora might be quite distinct from that in most plants such as Arabidopsis thaliana (A. thaliana) with only one abundant YTH protein. According to the analysis of the up-stream cis-regulatory elements of these YTH genes, these genes could be closely related to stress, hormones, and development. The following stress response experiments further verified that their expression levels indeed changed under both PEG and NaCl treatments. These findings not only provide a foundation for future functional analysis of CcYTHs in C. camphora, but also provide insights into the functions of epigenetic mark m⁶A in forest trees. Full article

The increase in the global atmospheric CO₂ concentration is expected to increase the productivity of forests, but the dynamic processes of such increased productivity in the forest canopy remain unclear. In this study, diurnal and seasonal variations and vertical changes in photosynthetic rates were investigated in Camphor tree (Cinnamomum camphora) forests in subtropical China. The effect of photosynthetically active radiation (PAR) and CO₂ concentrations on photosynthetic rates were also examined in the studied forests. Results showed the diurnal patterns of photosynthesis exhibited two peaks on sunny days, but only one peak on cloudy days. The daily average photosynthetic rate on cloudy days was approximately 74% of that on sunny days. The photosynthetic rate decreased along the vertical forest canopy profile. If the photosynthetic rate in the upper canopy layer was 100%, the corresponding rates were 83% and 25% in the middle and lower canopy layers, respectively. The rates of dark respiration derived from the PAR response curve were 1.73, 1.25, and 1.0 µmol m⁻² s⁻¹ for the upper, middle, and lower canopy layers, respectively. The apparent quantum yield of photosynthesis was 0.0183, 0.0186, and 0.0327 µmol CO₂ µmol⁻¹ PAR for the upper, middle, and lower canopy, respectively. The initial slope of the photosynthetic response curve to CO₂ was highest in the upper canopy and lowest in the lower canopy. The seasonal variation in photosynthetic rates exhibited a two-peaked pattern at all canopy positions, with the two peaks occurring in June and September. The stand biomass and biomass carbon storage were 144.7 t ha⁻¹ and 71.6 t C ha⁻¹ in the examined forests, respectively. The study provides a scientific reference for future research on accessing carbon sequestration and designing forest management practices, specifically in regulating canopy structure in subtropical regions. Full article

On a global scale, soil respiration (R_s), representing the CO₂ flux between the soil surface and the atmosphere, ranks as the second-largest terrestrial carbon (C) flux. Understanding the dynamics between R_s and its autotrophic (R_a) and heterotrophic (R_h) components is necessary for accurately evaluating and predicting global C balance and net ecosystem production under environmental change. In this study, we conducted a two-year root exclusion experiment in subtropical China’s Camphor (Cinnamomum camphora (L.) Presl.) forests to assess seasonal changes in R_a and R_h and their relative contributions to R_s. Additionally, we examined the influence of environmental factors on the dynamics of R_a, R_h, and R_s. Our results showed that seasonal mean R_s values were 2.88 µmol m⁻² s⁻¹, with mean R_a and R_h of 1.21 and 1.67 µmol m⁻² s⁻¹, respectively, in the studied forests. On an annual basis, the annual values of mean R_s in the studied forests were 405 ± 219 g C m⁻² year⁻¹, with R_h and R_a accounting for 240 ± 120 and 164 ± 102 g C m⁻² year⁻¹, respectively. The seasonal mean ratio of R_h to R_s (R_h/R_s) was 58%, varying from 45 to 81%. Seasonal changes in R_s and R_h were strongly correlated with soil temperature but not soil water content. Both R_h and R_s increased exponentially with the average soil temperature measured in the topsoil layer (about 5 cm), with Q₁₀ values of 2.02 and 1.73 for R_h and R_s, respectively. Our results suggest that the composition and activity of soil microbes and fauna play a primary role in releasing carbon flux from soil to the atmosphere in the studied forest ecosystems. Full article