Tree Age Research Articles

Diameter Increment Estimations of Open-Grown Stone Pine (Pinus pinea L.) Trees in Urban Parks in Istanbul, Türkiye

Open-grown trees in cities can improve environmental conditions by providing sustainable ecosystem services. Reliable data are necessary for assessing the functions of urban trees. The diameter at breast height (DBH), diameter increment, and annual ring measurements are the main parameters in the development of reliable models. To model periodic mean diameter increments calculated for different time periods (5, 10, 15, 20, and 25 years), a total of 43 open-grown stone pines (Pinus pinea L.) of different diameter classes were sampled in several urban parks in Istanbul, Türkiye. The DBH was measured, and increment cores were extracted from each tree at 1.30 m stem height using an increment borer. Tree age at breast height was determined by counting annual rings, and periodic mean diameter increments were calculated for different periods based on the measured tree-ring widths. The periodic mean increments of different periods were related to the inside-bark diameter at breast height and tree age. Since there was no significant relationship between tree age and periodic mean increments for each period’s length, as shown in the correlation analysis, models used to estimate the periodic mean increments of inside-bark DBH were developed using the least squares regression and quantile regression (QR) techniques. As the period length increased, the estimation success of the diameter increment models increased while the mean absolute percentage error (MAE) values decreased from 40 to 32%. The best model was the one used for the last 25-year period with the quantile value q = 0.50 which estimated the diameter increment with an RMSE = 1.391 mm/year and MAE = 32.27%.

Relationship Between Age and Condensed Tannin Content in the Bark of Two Forest Species Grown in Northeast Brazil

Objective: This research aimed to evaluate the influence of tree age on the condensed tannins content in the bark of two forest species. Theoretical Framework: Tannins are phenolic compounds present in various parts of plants and have consolidated applications in the market. This way, silvicultural studies of different species with the potential to produce are relevant. Method: Barks of Azadirachta indica at 5, 6, and 7 years and Mimosa caesalpiniaefolia at 6, 7, and 9 years were collected from an experimental plantation located in a forest area in Rio Grande do Norte, Brazil. The barks were then air-dried and ground to obtain a material subjected to extraction. Total solids content, Stiasny index, and condensed tannin content were determined from the hot-water extracts. Results and Discussion: The condensed tannins content in A. indica bark did not vary as tree age increased, while for M. caesalpiniaefolia, the most productive age was determined to be six years old. Research Implications: The experimental approach showed that A. indica presented stable tannin content in the bark regardless of age, allowing continuous and flexible management to produce these extractives. In contrast, M. caesalpiniifolia presented condensed tannins, with their reactivity decreasing with age, indicating that younger trees are more suitable for high-quality extractions and commercial production. Originality/Value: Tannins content in Azadirachta indica bark remains stable over time, facilitating continuous management and Mimosa caesalpiniifolia bark, the concentration of tannins is higher in younger trees.

Community assembly and potential function analysis of the endophyte in Eucommia ulmoides

Endophytes play a pivotal role in protecting host plants from both biotic and abiotic stresses, promoting the production of active components (AC) and plant growth. However, the succession of the endophyte community in Eucommia ulmoides (E. ulmoides), particularly the community assembly and function, has not been extensively investigated. In this study, we employed high-throughput sequencing and bioinformatics tools to analyze endophyte diversity across different tree ages, parts, and periods. We examined the population differences, correlations, community assembly mechanisms, and functional roles of these endophytes. Functional predictions via PICRUSt2 revealed that most endophytic fungal functions were linked to biosynthesis, with significant differences in biosynthetic functional abundance across parts and periods. In contrast, the metabolic activity of endophytic bacteria remained stable across different periods and parts. Correlation analysis further confirmed a strong positive relationship between ACs and certain endophytic fungi. Among them, the fungal phyla Ascomycota and Basidiomycota were identified as key contributors to the metabolism of chlorogenic acid (CA), while Aucubin was significantly positively correlated with several endophytic bacteria. These findings provide valuable insights into the functional roles and community assembly mechanism of E. ulmoides endophytes, as well as their symbiotic relationships.

Decoupling of Tree‐Ring Cellulose δ18O and δ2H Highlighted by Their Contrasting Relationships to Climate and Tree Intrinsic Variables

ABSTRACTOxygen (δ18O) and hydrogen (δ2H) stable isotope ratios are tightly coupled in precipitation and, albeit damped, in leaf water, but are often decoupled in tree‐ring cellulose. The environmental and physiological conditions in which this decoupling occurs are not yet well understood. We investigated the relationships between δ18O and δ2H and tree‐ring width (TRW), tree crown volume, tree age and climate in silver fir and Douglas‐fir and found substantial differences between δ18O and δ2H. Overall, δ18O–δ2H correlations were weak to absent but became significantly negative under high summer vapour pressure deficit (VPD). δ18O and δ2H had positive and negative nonlinear relationships with TRW, respectively, with clear relationships at the site and tree levels for silver fir and, to a lesser extent, for Douglas‐fir. Age trends for silver fir were weakly negative in δ18O but positive in δ2H. Tree crown volume and δ18O or δ2H had no significant relationships. Most strikingly, δ18O strongly depended on spring climate (precipitation and VPD), whereas δ2H depended on summer climate (temperature and VPD) for both species. Our study shows that the δ18O–δ2H decoupling in tree‐ring cellulose in two temperate conifer species could be highlighted by their contrasting relationships to climate and tree intrinsic variables (TRW, age).

Exploring the correlation between tree structure characteristics and carbon storage in historic gardens using TLS technology: a case study of Jian Xin Pavilions at Jingyi Park, Fragrant Hills Park

Historic gardens contain a greater number and variety of ancient trees, which are older, have unique forms, and larger volumes. These trees hold significant value in both natural ecosystems and cultural heritage. However, current research on the carbon sequestration value of ancient and non-ancient trees in historical gardens is relatively lacking. Based on the unique morphology and carbon storage estimation needs of ancient trees in historic gardens, this paper proposes a morphology-based point cloud single-tree segmentation method. This method can precisely extract the morphological structures of various tree species and accurately estimate their carbon storage. From the perspective of carbon sequestration, it evaluates the correlation between the structural characteristics and carbon storage of trees in historic gardens, as well as the potential changes in their carbon storage capacity.Using the Jing Yi Park’s Jian Xin Pavilions in Fragrant Hills Park as a case study, this method was applied to extract structural indicators of 116 ancient and non-ancient trees. The total carbon storage was found to be 19,171.13 kg, with an average carbon storage of 165.27 kg per tree. Among these, ancient trees accounted for 13,178.32 kg, or 68.74% of the total carbon storage. The study revealed that the correlation between tree age and carbon storage varied by species, and there were significant positive correlations between carbon storage and tree height, DBH, and canopy volume. Notably, there was a significant linear growth trend between DBH, canopy volume, and carbon storage. By 2030, the total carbon storage is projected to increase to 21,924.96 kg, with an annual average increase of 393.40 kg, representing a growth rate of 14.4%.The results indicate that studying the correlation between structural characteristics and carbon storage of aged trees in historical gardens can shed light on the important role of trees in sustainable carbon sequestration. The precise extraction of tree information through 3D digital technology and the prediction of carbon storage potential not only offer new perspectives for the conservation of cultural heritage in historical gardens, urban microclimate planning and design, and spatial management of carbon sinks and emissions but also have significant value for promoting the scientific management and protection of urban green spaces.

Growth trends of loblolly pine age five or less in relation to soil type and management intensity

We evaluated three objectives for loblolly pine (Pinus taeda L.) trees age five or less: 1) how height growth varies by soil type and silvicultural intensity, 2) the accuracy of predicted base-age 25 site index (SI25) using age one to five heights, and 3) if height dominance exhibited early in the rotation is maintained throughout the rotation. Data from 42 sites across the southeastern United States with an array of soil textures and management intensities (optimal, intensive, and operational) were used. Management intensity and soils significantly affected tree height. Coarse loamy soils were the most responsive to increasing management intensity. At age four, tree heights were greatest in the optimal group (4.63 m), followed by the intensive (4.31 m), and then the operational (3.06 m). Organic soils do not appear to respond to maximum management intensity. Predictability of SI25 was high especially starting at age four, with R2 values ranging from 0.27 for the age four intensive group to 0.78 for the age four operational group. The optimal group had the greatest slope with an expected increase of 2.61, 2.75, 1.88, and 1.78 m in site index per additional meter of height at ages two, three, four, or five, respectively. Data from six different study sites indicate, the tallest (class one) and smallest (class five) trees changed percentile class the least often over time. As early as age two, over 40 % of observations in classes one and five had zero changes in class through age 13. Young tree data were effective in predicting SI25, and height dominance appeared generally set early in the rotation.

Assessing vertical seed dispersal through seed oxygen isotope ratios of Japanese larch (Larix kaempferi)

AbstractVertical seed dispersal, involving seed movement to higher or lower elevations, plays a vital role in plant adaptation to rising temperatures. However, its assessment has been limited owing to labor‐intensive processes. A recently developed method exploits the negative correlation between elevation and seed oxygen isotope ratios (18O/16O; hereafter δ18O) for efficient evaluation of vertical seed dispersal. Nevertheless, it remains unclear whether this method is suitable for conifers and whether plant size and age introduce noise into δ18O values, which would affect vertical seed dispersal estimations. In this study, we investigated the association between elevation and seed δ18O values of Japanese larch (Larix kaempferi) and explored the relationship among these oxygen isotope ratios, tree height, diameter at breast height (DBH), and age. Notably, we found a negative correlation between elevation and seed δ18O values of L. kaempferi but failed to detect any influence of tree height, DBH, and age on these oxygen isotope ratios. These findings suggest this method's potential for accurately estimating vertical seed dispersal across diverse plant lineages.

Radiocarbon ageing of Indigenous culturally‐significant trees for bushfire management on Minjerribah (North Stradbroke Island), southeast Queensland

SummaryPartnerships between Indigenous People and governments for joint management of ancestral lands, designated as protected conservation areas for biodiversity and cultural heritage, provide an opportunity to leverage accumulated traditional land management knowledge with emerging science. In Australia, veteran or large old trees in natural landscapes are of significant ecological importance, and among the Indigenous communities, they are living monuments to historical cultural practices, but their survival, endurance and long lives are rarely acknowledged to afford them protection. In sub‐tropical Australia, the lack of consistent annual growth rings in stem wood makes it difficult to estimate the age of large trees using methods such as the periodic diameter increment. Ngugi et al., 2020 published radiocarbon (14C) dates using wood core (‘pith‐wood’) samples from 12 Indigenous culturally‐significant trees covering five species on Minjerribah (North Stradbroke Island). Due to the imprecise calendar age results of the single samples used in the original study (Ngugi et al., 2020), subsequent radiocarbon dating of an additional three wood core samples from each tree was undertaken to age the trees more precisely. The revised tree ages ranged from 63 to 531 years and suggest an important role of past Indigenous land management practices into protecting Bugari (Cypress Pine, Callitris columellaris F. Muell.) from deadly crown scorching fires. These results underscore the importance of incorporating Indigenous practices in current fire management strategies and plans. Estimating tree ages based on the periodic diameter increment method overestimated the age relative to that derived from radiocarbon dating. New bias correction factors were developed for adjusting the recorded periodic tree diameter increments.

Impacts of groundwater depth and tree age on the non-structural carbohydrates of Haloxylon ammodendron

Nonstructural carbohydrates (NSCs) are important substrates for plant growth and metabolism, and their concentration reflects the plant's ability to adapt to environmental changes. Although the response of NSCs to changes in water availability has been extensively studied, it is still not fully understood whether this response is modulated by tree ages and organs. This study investigates Haloxylon ammodendron (C.A. Mey.) Bunge ex Fenzl, the dominant species in the Gurbantunggut Desert in the Uyghur Autonomous Region of China. Utilizing the natural topographic conditions characterized by a gradual increase in groundwater depth from the desert edge to the interior, we collected samples of different age classes of H. ammodendron along a groundwater depth gradient of 3, 7, 10, and 14 meters. We measured the total concentrations of non-structural carbohydrates (NSCs) and their components soluble sugar (SS) and starch (ST) in the assimilative twigs and stems. The results showed that the assimilative twigs of H. ammodendron exhibited higher NSC concentrations at the site with the deepest groundwater, while the other three sites showed similar NSC concentrations. Furthermore, as groundwater depth increased, the concentrations of SS in the assimilative twigs increased, whereas ST concentrations decreased. Similarly, the concentrations of SS in the stems also increased at sites with deeper groundwater. The NSC concentrations in the assimilative twigs were significantly affected by groundwater depth, while variations in stem NSC were primarily driven by plant age. In younger trees, higher soluble sugars concentrations in the stem may enhance water transport efficiency, whereas older trees tend to store more NSC to alleviate drought stress. Overall, elevated nonstructural carbohydrate concentrations contributed to greater drought resilience in H. ammodendron. These results suggest that different age classes of H. ammodendron exhibit distinct physiological responses to decreasing groundwater depth. The varying requirements for soluble sugars and starch in H. ammodendron help to partially mitigate the adverse effects of reduced groundwater accessibility. These findings provide important insights into the physiological adaptations of H. ammodendron in arid environments and offer a scientific basis for future ecological restoration and management strategies.

Patterns and drivers of cottonwood mortality in the middle Rio Grande, New Mexico, USA

AbstractRiparian ecosystems are some of the most valuable and vulnerable on the planet. Riparian tree mortality is increasing in the western United States, where altered streamflows are combining with warming climate. Between 2011 and 2013, one third of an extensive stand of Populus deltoides var. wislizeni (Rio Grande cottonwood) died along the middle Rio Grande on the Pueblo of Santa Ana in New Mexico. Mortality coincided with a severe drought that followed a decade of decreasing streamflow, but it was heterogeneous, with adjacent patches of dead and live trees. The goal of this research was to determine the drivers of mortality to provide insights into future risks of die‐off and potential management interventions. We compared tree age, competition, tree‐ring widths, sediment particle size and climate influences between live and dead forest patches in a nested plot design. Live and dead trees had similar age, stand density and particle sizes of shallow sediments. Tree‐ring widths had the highest correlations with July–September streamflow (1932–2013). All trees had declining ring growth since 1992, coinciding with declining late summer streamflow. An accelerated decline in growth began in 2002, corresponding to recent warmer droughts. Trees that died had lower ring growth 3 years prior to death and in the mid‐1900s. Dead trees also had coarser deep sediments 2.4–3.7 m below ground, suggesting that reduced water holding capacity was an important factor for mortality. Water management to increase streamflow during the late summer, especially during times of extended drought, could reduce mortality risk in the face of projected increasingly warm droughts.

Distribution and Abundance of Pine Needle Aphids (Eulachnus rileyi Williams) and Their Potential Natural Enemies on Pine Tree Species (Pinus patula and Pinus elliottii) at Sao Hill Forest Plantation, Tanzania

A study was conducted at SHFP, Tanzania to assess the distribution and abundance of PNA and their potential natural enemies. Systematic sampling was used to select every 5th tree along the row of the particular compartment. Five shoots were randomly cut from lower, middle and upper crown parts of each selected tree for laboratory analysis. Data analysis was performed using R and Excel, with normality and homogeneity of variance checked using Shapiro-Wilk and Levene’s tests, respectively. Results revealed that PNA was un-equally distributed throughout the divisions, trees species and age classes at SHFP. The abundance of adult aphids per twig was 7.6 and 12.9 for Division II and III, respectively and was significantly different. Similarly, the mean abundance of eggs and nymphs per twig were 5.5 and 12.2 in Division II and 9.2 and 21.1 in Division III, respectively. Nymphs were more abundant than eggs and adults, while eggs were the least abundant across all examined pine species and age classes. The abundance of adult aphid was 19.6 and 7.0 for P. elliottii and P. patula, respectively and was significantly different. For P. patula, the abundance of adult aphid per twig was 7.3, 8.5 and 5.1 for young, middle and old age classes respectively. In P. elliottii stands, the abundance of adult aphid population per twig was 23.2 and 17.9 for middle and old age classes respectively. The middle part of the tree crown had the highest aphid abundance for both tree species and age classes. Three main natural enemies were identified: Coccinellid beetles (Coleoptera: Coccinellidae), Spiders (Arachnida) and Stink bugs (Pentatomidae), but their numbers were low. The correlation between the abundance of PNA and natural enemies was weakly positive (Rho = 0.0859) but statistically significant (p = 0.035). Tending operations i.e. thinning, weeding, pruning, and regular insect survey and monitoring programs, are recommended to mitigate favorable conditions for aphid growth. Additionally, the SHFP management team should reconsider the introduction and release of Tetraphleps raoi or other predators as biological control agents over large area to increase the current stock of the natural enemies as there were no introduce natural enemies found in the plantation

Effects of Rainfall and Harvest Time on Postharvest Storage Performance of ‘Redson’ Fruit: A New Red Pomelo x Grapefruit Hybrid

‘Redson’ is a new triploid, red-fleshed pomelo × grapefruit hybrid. The goal of this study was to examine the effects of rainfall, harvest time, tree age, and yield on the postharvest storage performance of ‘Redson’ fruit. During 2022/23, two postharvest storage trials were conducted with early- and late-harvested fruit. The fruit from the early harvest retained good quality for up to 16 weeks of storage at 7.5 °C plus 1 week at 22 °C, whereas the late-harvested fruit suffered from a high decay incidence. During 2023/24, we expanded the postharvest trials to nine different fruit sets harvested from early season (late October) until the end of the season (January). Fruit quality was examined under the same storage conditions after 6 and 16 weeks, and the results indicated that early- and mid-season fruit retained good quality with minimal decay incidence even after prolonged storage for 16 weeks, whereas the late-season fruit suffered from significant decay incidences of 17–22% and a decline in flavor acceptability. Further analysis revealed strong and significant correlations between various rainfall parameters and harvest time and decay incidences. Overall, early-harvested fruit during the autumn had a superior postharvest storage performance, whereas late-harvested fruit during the rainy winter suffered from decay development.

Stand Characteristics, Leaf Traits and Growth of Threatened Conifer Pilgerodendron uviferum (Cupressaceae) in Southern Patagonia, Argentina

Pilgerodendron uviferum is an endemic Cupressaceae of Patagonia (Argentina) that is restricted to a small group of individual trees, growing in isolated populations (relicts) along its distribution. The main objective was to evaluate the habitat, forest structure, leaf traits, leaf nutrient reabsorption and growth of four relicts (area between 0.3 and 0.86 ha) in the Santa Cruz province (Argentina) to improve the available information for forest conservation purposes. Principal components analysis was conducted to determine the separation between relict populations based on their ecological characteristics (individual and habitat levels). We found contrasting environmental and forest structure conditions among the four studied relicts. For example, two relicts associated with Nothofagus antarctica showed higher values of P. uviferum tree density, DBH and dominant height at the stand level. Alongside that, these relicts presented a higher sapling density (1950–3167 ind ha−1) and understory plant diversity compared to pure P. uviferum relicts growing near the ecotone with the steppe grassland. Specific leaf area, carbon and nutrient concentrations in P. univerum leaves varied depending on the relict conditions and tree age of the individuals. The mean nutrient resorption efficiency varied according to relicts and particular nutrients, ranging from 18.1% to 49.5% for Ca and P, respectively. The diameter growth of the dominant P. univerum trees ranged from 0.33 to 0.46 mm yr−1, indicating that the species follows a stress-tolerant strategy. The information of this work may assist in the conservation of marginal P. uviferum forest communities spatially disconnected with continuous forests, growing in relicts.

Tetranychus urticae Koch Biology on Apple Trees

The two-spotted spider mite (Tetranychus urticae Koch) is a polyphagous arthropod herbivore that consumes over 1,100 plant species from 140 distinct plant families, including those producing harmful chemicals in temperate and tropical climates. It is an important pest in greenhouse and field cultivation, causing damage to various crops such as citrus, apples, grapes, tomatoes, peppers, cucumbers, strawberries, maize, and soy. T. urticae ability to spread over agricultural fields and adapt to environmental stressors is linked to its high propensity for mutation, leading to the highest frequency of pesticide resistance among arthropods. The genetic diversity of T. urticae gathered from apple orchards throughout Poland has been studied to investigate potential correlations between molecular variations and the occurrence of resistance to METI-acaricides. Research has shown that an abundance of leaf pubescence on the abaxial leaf surface adversely affects the development of European red mite, two-spotted spider mite, and carmine spider mite. However, due to variations in leaf sizes, tree canopy, tree ages, and the existence of natural enemies, it is impossible to compare data gathered due to variations in leaf sizes, tree canopy, tree ages, and the presence of natural enemies. Pesticide treatments negatively impact fruit plantations' ecosystems, devastating biodiversity, altering the makeup and structure of arthropod populations, and promoting mass reproduction of phytophage mites by displacing certain species with others. The most extensive research has been done on the common spider mite's development of resistance to avermectin group preparations, with some studies showing resistance to multiple acaricides.

Inter- and Intra-Annual Variations in Oak Tree Ring δ13C Values across Different Elevations and Their Climatic Responses in Qinling Mountains

The Qinling Mountains, serving as a natural geographical and climatic boundary in China, require comprehensive climatic records to elucidate the trends in climate changes across the country. While stable isotopes in tree rings are widely employed to indicate historical environmental changes, investigations into tree ring isotopes in the Qinling Mountains, particularly within the widespread broad-leaf oaks, remain limited. In this study, we investigated both intra- and inter-annual variations in the δ13C values of tree rings and their correlations with climatic signals over the past two decades for Quercus aliena var. acuteserrata, a dominant species among oak trees on the main peak of the Qinling Mountains. Our results reveal that responses to climate differ among altitudes and individual trees, with trees at higher altitudes exhibiting higher sensitivity to extreme climate, which is low temperatures and rainfall fluctuations during the growth period in intra-annual δ13C variations. Furthermore, the positive correlations are observed between temperature during growing season and both tree growth and the inter-annual δ13C variations. However, the climate signal appears to be hampered by oak-specific factors, such as intense competition among individuals and the age of trees. Therefore, we suggest a more rigorous selection of sampling and propose further investigations into isotopic fractionation processes in oaks for future studies.

What do trees reveal about the sliding of the lateral moraine of the Belvedere Glacier (western Italian Alps)?

The debris-covered Belvedere Glacier is an iconic place for investigating glacier dynamics and geomorphological processes typical of high mountain environments. Moreover, being located in an area highly suited to tourism, glacial and geomorphological hazards can evolve into risk scenarios. Particular attention has been paid during this research to the surge-type event that occurred at the beginning of the 21st century, and to the recent sliding of a lateral moraine nearby the chairlift station. Tree sampling was performed (19 trees on the lateral moraine; 10 undisturbed trees), and the results were compared with morphometric measurements on orthophotos of different years. Besides sampling trunks, the six available exposed roots (13 samples) from a tree located along the sliding niche were sampled to identify the exposure time. Morphometric measurements of the touristic trail dislocation indicate a sliding rate of 1.87 m/y – 1.98 m/y (2018–2023), while the regression rate of the sliding niche is 1.70 m/y (2021–2023). The age of trees along the trench is variable (14–49 years), as is the signal of compression wood, enhancing differentially the passage of the surge wave and the subsequent glacier downwasting. The beginning of root exposure occurred between 2017 and 2019, before the effective evidence of large fractures in the ground. Moreover, the roots show traumatic resin ducts in the period between 2020 and 2022, confirming the tree disturbance. In conclusion, the investigated events are recorded differentially in the sampled trees, especially in roots, anticipating the actual commencement of ground failure. A multidisciplinary approach, including remote sensing, field survey, and dendrogeomorphological analysis is essential to define the dynamics of complex systems.

Host genotype and age shape the microbial community in the rhizosphere soils of Camellia forests.

Microbiota living in the rhizosphere influences plant growth and fitness, from the opposite perspective; whether host genotypes control its root microbiota is of great interest to forest breeders and microbiologists. To improve low-yield plantations and promote sustainable management of Camellia oleifera, high-throughput sequencing was used to study the chemical properties and microbiome in rhizosphere soil of Camellia forests under three genotypes (common C. oleifera, local C. gauchowensis, and C. chekiangoleosa) and three growth stages (sapling stage at 4-year-old, primary fruit stage at 7-year-old, and full fruiting stage at 11-year-old). The results showed that the rhizosphere soil organic matter (OM), nutrient concentrations, diversity, and community composition of the microbiome were significantly varied among different Camellia genotypes. The relative abundance of symbiotic and pathotrophic fungi in the rhizosphere soil of C. chekiangoleosa was significantly higher than that of C. gauchowensis. Concentrations of OM, available phosphorus (AP), and bacterial alpha diversity increased with tree age. Fungi of Saitozyma, Mortierella, and Glomeromycota and bacteria of Burkholderia-Caballeronia-Paraburkholderia and Vicinamibacterales had potential for fertilizer development for Camellia plantation. Camellia genotypes and growth stages were significantly correlated with the rhizosphere soil pH, OM, and available potassium (AK). Soil pH and OM were key factors that affected the microbiome in the Camellia rhizosphere soils. In conclusion, tree genotypes and growth stages shaped microbial communities in Camellia rhizosphere soils, and some plant growth-promoting rhizobacteria were identified as preliminary candidates for improving Camellia plantation growth.

Increasing Ages of Inga punctata Tree Soils Facilitate Greater Fungal Community Abundance and Successional Development, and Efficiency of Microbial Organic Carbon Utilization

Leguminous Inga trees are thought to enhance soil carbon (C) accumulation following reforestation, through mostly unknown mechanisms. This study amplified soil DNA using the ITS1F and ITS4 primers for PCR and Illumina MiSeq methods to identify fungal taxa, and traditional C analysis methods to evaluate how planted 4-, 8-, and 11-year-old Inga punctata trees affected soil fungal community compositions and C utilization patterns compared to old-growth I. punctata trees and an adjacent unplanted pasture within the same reforestation zone in Monteverde, Costa Rica. Along the tree age gradient, the planted I. punctata trees enhanced the tree soil C capture capacity, as indicated by increased levels of soil biomass C, Respiration, and efficiency of organic C use (with lower qCO2 values), and development of increasingly more abundant, stable, and successionally developed fungal communities, including those associated with the decomposition of complex organic C compounds. The level and strength of differences coincided with differences in the time of separation between the pasture and tree age or between the different tree ages. Fungal taxa were also identified as potential indicators of the early and late stages of soil recovery. Thus, planting I. punctata should be part of future reforestation strategies used in this region of the Monteverde Cloud Forest in Costa Rica.

Changes in Arenosol Nematode Abundance and Trophic Composition as Influenced by Different Faidherbia albida (Delile) A. Chev. Tree Stand Ages in Northern Ethiopia

ABSTRACTFaidherbia albida (Delile) A. Chev., hereafter F. albida is an important agroforestry tree species in the semi‐arid highlands of Tigray, northern Ethiopia. The paper analyses how different stand ages of the tree could influence nematodes' abundance, trophic composition and selected community index values. A total of 40 composite soil samples were collected from out‐canopies and under‐canopies of different tree stand age classes designated as young (15–20 years), medium age (35–40 years) and older (> 60 years). Nematodes were extracted following the Baermann funnel technique, identified and counted under an inverted Olympus microscope according to their trophic groups. The highest total count of nematodes and relative abundance of fungivores, omnivores and predatory nematode trophic groups were counted from soil samples influenced by older F. albida trees. The relative abundance of bacterivores and plant parasitic nematodes was low. The nematode channel ratio became lower in soils as influenced by older trees while the Wasilewska index was significantly high. The age difference of the trees influenced the abundance of the soil nematode feeding groups and their ecological index values. Moreover, the results have shown the enhancement of nematode trophic diversity. Redundancy analysis showed that tree age significantly influenced the relationships of nematode trophic groups with the studied soil bio‐physicochemical properties. Generally, the findings indicate that the soil food web becomes more complex and functional under the older trees.

Carbon Sequestration of Common Garden Tree Species under the Carbon Neutrality Target in East China

The global warming phenomenon caused by greenhouse gas emission leads to the deterioration of the ecological environment. In urban spaces, the selection of garden tree species with high carbon sequestration rates can effectively contribute to carbon neutrality. In this study, we measured the height, diameter at breast height, and crown width of 643 ancient trees around the West Lake Scenic Spot, Hangzhou, China, and recorded their species and ages. By the biomass expansion factor method, the long-term carbon sequestration of the trees was calculated, and the corresponding statistical analysis indicated the following findings: (1) The maximum carbon sequestration of ancient trees varies with the species; the simple rational function has the best fit for the relationship between mean annual carbon sequestration and age. (2) For the five most common species in the Hangzhou area, the total individual amount of carbon sequestration per tree species can be ranked from high to low as follows: Celtis julianae, Cinnamomum camphora, Castanopsis sclerophylla, Liquidambar formosana, and Ginkgo biloba (tree age < 260 years). The ranking for trees aged above 260 years is as follows: Celtis julianae, Cinnamomum camphora, Liquidambar formosana, Castanopsis sclerophylla, and Ginkgo biloba. (3) The transient and mean annual carbon sequestration rate decreases as tree age increases; for most of the ancient trees in this research, the main growing period is 0–300 years. (4) Castanopsis sclerophylla, Liquidambar Formosana, and Osmanthus fragrans are recommended for urban landscape greening as they provide continuous long-term carbon sequestration and special landscape features.