Forest Ecosystems Research Articles

Impact of Climate and Vegetation Dynamics on the Ecosystem Services of Subtropical Forests—A Case Study of Baishanzu National Park Area, China

Forest ecosystems, as the primary component of terrestrial ecosystems, provide essential ecosystem services (ESs) critical for sustainable human development. However, changes in climate and vegetation can alter these forest ESs. Understanding the complex relationships between regional climate, vegetation, and ESs is key to ensuring the sustainable management of forest ESs. Therefore, this study, using Baishanzu National Park as a case example, analyzed the impacts of regional climate and vegetation dynamics (vegetation coverage, forest type, and forest structure) on forest ESs, specifically water yield (WY), soil conservation (SC), net primary productivity (NPP), and habitat quality (HQ). The results indicate that from 2000 to 2020, the forest Composite Index of Ecosystem Services (CIES) in Baishanzu National Park increased. Climate and vegetation dynamics have significant effects on forest ESs. Specifically, changes in WY and SC are primarily influenced by climate change, while changes in NPP and HQ are mainly affected by changes in forest type and structure. Complex trade-offs and synergies exist among different ESs, and the driving mechanisms of climate and vegetation changes on ES variations are also complex, involving both direct and indirect effects, with significant spatial heterogeneity. This study provides important references for the sustainable management and appropriate restoration of regional forest ESs.

Assessing the Impacts of Nature-Based Solutions on Ecosystem Services: A Water-Energy-Food-Ecosystems Nexus Approach in the Nima River Sub-Basin (Colombia)

Forest ecosystem services are critical for maintaining ecological balance and supporting human well-being from different perspectives. However, rapid land use changes driven by agricultural expansion, urbanization, and industrial activities have significantly altered forest ecosystems, degrading the services they provide. We here conduct an ecosystem service assessment through biophysical and economic estimates for a multipurpose Andean water sub-basin in western Colombia. We compare a business as usual (BAU) with a forest nature-based solution (NbS) scenario focused on forest landscape restoration. The research employed participatory methods for the NbS selection and economic valuation techniques to evaluate water flow regulation, water provisioning, water purification, and food provisioning services. Results show that the NbS scenario yielded a net positive economic impact across most evaluated ecosystem services, with notable trade-offs. Specifically, the NbS scenario increased water retention by 2.9% compared to BAU. Water flow regulation demonstrated the most substantial economic benefit, increasing by EUR 11.39 million/year in the NbS scenario. On the other hand, the food provisioning service presented a reduction of EUR 3.2 million/year in the NbS scenario. These findings highlight the potential of forest-based NbS to address the Water–Energy–Food–Ecosystem (WEFE) nexus challenges. The study’s outcomes provide valuable insights for policymakers and practitioners, supporting the development of Payment for Ecosystem Services schemes and integrating ecosystem service valuation into land use planning and decision-making processes.

Metabarcoding reveals that arboreal habitats contribute significantly to nematode diversity in different forest ecosystems

Metabarcoding reveals that arboreal habitats contribute significantly to nematode diversity in different forest ecosystems

Naturalization of the Ornamental Plant Crocus tommasinianus Herb. (Iridaceae) in Forest Ecosystems: A Case Study from Poland

Highlights: Though not highly invasive, bulb and corm ornamental plants can escape cultivation and naturalize in new areas. Studying their naturalization is key to understanding their ecological impact and managing biodiversity. Objectives: This study aimed to document the first naturalization case of Crocus tommasinianus Herb. in Poland and assess the morphological variability of the naturalized population under different environmental conditions. Another objective was to identify diagnostic features in seed testa ornamentation to distinguish C. tommasinianus from related species (C. vernus (L.) Hill. and C. scepusiensis (Rehmann et Wol.) Borbás ex Kulcz.). Methods: The morphometric studies were performed within four subpopulations of C. tommasinianus differing in environmental conditions, determined with Ellenberg indices. Multivariate tests, ANOVA, and post-hoc tests were used to determine the morphometric diversity of specimens and to relate them to environmental factors. Seed micro-ornamentation was examined using a scanning electron microscope. Results: Light and temperature were negatively correlated, while moisture, soil pH, and nitrogen were positively correlated with many morphological traits. Plants spreading into forest ecosystems exhibited better-developed features (larger leaves and flowers) than those in former cultivation sites, indicating higher survival potential. The seed coat is papillate, with distinct differences in the shape, size, and secondary sculpture of the papillae compared to C. vernus and C. scepusiensis. Given that floristic studies often occur during the fruiting period of crocuses, testa ornamentation is crucial for identifying the studied species. Conclusions: The observed naturalization of C. tommasinianus demonstrates the high morphological plasticity of plants, which makes them capable of colonizing new areas, including forest habitats.

Distribution characteristics of soil active organic carbon at different elevations and its effects on microbial communities in southeast Tibet

Global mountain ecosystems have garnered significant attention due to their rich biodiversity and crucial ecological functions; however, there is a dearth of research on the variations in soil active organic carbon across altitudinal gradients and their impacts on microbial communities. In this study, soil samples at an altitude of 3,800 m to 4,400 m were collected from Sejira Mountain in the southeast Tibet, and soil active organic carbon components, soil microbial community diversity, composition and structure distribution and their relationships were systematically analyzed. The results revealed a non-linear relationship between the elevation and the contents of soil organic carbon (SOC) and easily oxidized organic carbon (ROC), with an initial increase followed by a subsequent decrease, reaching their peak at an altitude of 4,200 m. The Shannon diversity of bacteria exhibited a significant decrease with increasing altitude, whereas no significant change was observed in the diversity of fungi. The bacterial community primarily comprised Acidobacteria, Proteobacteria, Chloroflexi, and Actinobacteriota. Among them, the relative abundance of Proteobacteria exhibited a negative correlation with increasing altitude, whereas Actinobacteriota demonstrated a positive correlation with elevation. The fungal communities primarily consisted of Basidiomycota, Ascomycota, and Mortierellomycota, with Ascomycota prevailing at lower altitudes and Basidiomycota dominating at higher altitudes. The diversity and composition of bacterial communities were primarily influenced by altitude, SOC, ROC, and POC (particulate organic carbon). Soil carbon-to-nitrogen ratio (C/N), dissolved organic carbon (DOC), and available phosphorus (AP) emerged as key factors influencing fungal community diversity, while POC played a pivotal role in shaping the composition and structure of the fungal community. In conclusion, we believe that soil active organic carbon components had a greater impact on the bacterial community in the primary forest ecosystem in southeast Tibet with the elevation gradient increasing, which provided a theoretical basis for further understanding of the relationship between the microbial community and soil carbon cycle in the plateau mountain ecosystem under the background of climate change.

Where to start with climate-smart forest management? Climatic risk for forest-based mitigation

Abstract. Natural disturbances like windthrows or forest fires alter the provision of forest ecosystem services such as timber production, protection from natural hazards, and carbon sequestration. After a disturbance, forests release large amounts of carbon and therefore change their status from carbon sinks to carbon sources for some time. Climate-smart forest management may decrease forest vulnerability to disturbances and thus reduce carbon emissions as a consequence of future disturbances. But how can we prioritise the stands most in need of climate-smart management? In this study we adopted a risk mapping framework (hazard times vulnerability) to assess the risk to climate-related forest ecosystem services (carbon stock and sink) in forests prone to windthrow (in the Julian Alps, Italy) and forest fires (in the Apennines, Italy). We calculated hazard by using forest fire and windthrow simulation tools and examined the most important drivers of the respective hazards. We then assessed vulnerability by calculating current carbon stocks and sinks in each forest stand. We combined these values together with the calculated hazard to estimate “carbon risk” and prioritised high-risk stands for climate-smart management. Our findings demonstrate that combining disturbance simulation tools and forest carbon measurements may aid in risk-related decision-making in forests and in planning decisions for climate-smart forestry. This approach may be replicated in other mountain forests to enhance our understanding of their actual carbon vulnerability to forest disturbances.

Ground beetle trophic interactions alter available nitrogen in forest soil

It is generally held that microbes exert primary control over nitrogen availability in temperate forests. Yet the role of soil and litter‐dwelling invertebrates to provide additional control via the breakdown of organic matter is an area of current exploration. Through trophic interactions within soil food webs, predators may indirectly affect prey with cascading effects on litter breakdown and nitrogen availability. The importance of these interactions, however, may be context‐dependent, varying with the stage of forest development and associated decomposer species composition given that young and old forests have vast differences in nitrogen availability, vegetation litter, soil properties and invertebrate functional groups. We examined ground beetle control over soil nitrogen and soil properties using a 68‐day mesocosm experiment that manipulated trophic structure (omnivore + predator beetles, predator beetles, and no beetles) in a young and old forest stand in the northeastern United States. In the young forest, net nitrogen mineralization decreased under predator + omnivore and the bulk soil C:N ratio in the old forest. However, we found no response in either forest context to the predator only treatment. Our study demonstrates the potential for ground beetles to strongly impact nitrogen availability and soil properties in forest ecosystems. Therefore, animal trophic interactions and their contexts must be included in our paradigm of nutrient cycles in temperate forests.

Application of Bayesian Causal Inference in the Study of the Relationship Between Biodiversity and Aboveground Biomass of Subtropical Forest in Eastern China

The relationship between biodiversity and ecosystem function is crucial for understanding the structure and processes of subtropical forest ecosystems. However, the extent to which biodiversity influences subtropical forest biomass remains unclear. This study applies Bayesian causal inference to explore causal relationships between forest Aboveground Biomass (AGB) and its potential driving factors (biodiversity factors, biotic factors and abiotic factors) based on Huangshan Forest Dynamics Plots. Furthermore, hypothetical interventions are introduced to these driving factors within the causal network to estimate their potential impact on AGB. The causal relationship network reveals that species diversity and functional diversity are the most direct factors influencing AGB, whereas phylogenetic diversity exerts only an indirect effect. Biotic and abiotic factors also contribute indirect effects on AGB, potentially by influencing other mediating indexes. Intervention analysis shows that with low-level interventions on direct influencing factors, the probability of low AGB is as high as 84%. As the intervention level increases to high, the probability of low AGB decreases by 36%. Moreover, AGB demonstrates a particularly sensitive response to changes in Rao’s quadratic entropy (RaoQ) intervention levels, more so than to other factors, highlighting its critical role in maintaining forest biomass. Therefore, we contend that functional diversity, due to its direct reflection of species’ roles in ecosystem processes, is a more accurate measure of the impact of biodiversity on biomass compared to species or phylogenetic diversity and the interplay between abiotic and biotic factors and biodiversity should not be overlooked. This approach offers a powerful tool for exploring causal relationships, thereby providing a more nuanced and accurate understanding of the relationship between biodiversity and forest ecosystem function.

Legacy effect of 25 years reduced atmospheric sulphur deposition on spruce tree nutrition

AbstractBackgroundSince the mid‐1990s, sulphur (S) pollution was drastically reduced in Central Europe. Over time, this has led to a distinct reduction in S availability for Norway spruce (Picea abies Karst.), which is still the most important timber species in Central European forestries.AimsDetermination of the Norway spruce nutritional status of former strongly affected areas by S pollution (Saxony) with different degrees of liming by assessing their foliar element contents and comparing them to regions remote from historical high S deposition.MethodsSites were selected based on levels of S deposition in the 1970–1990s with historical high deposition in Saxony (NE Germany), low deposition at Schluchsee (SW Germany) and Davos (Switzerland) as a clean air reference. Needles were sampled in late autumn 2019/2020 and elemental contents determined. Additional historical data on foliar S contents were available.ResultsHistorical data showed a clear decrease in foliar S contents in the Saxonian sites over the last 25 years, independent of liming. No difference between all study sites was found in the most recent sampling, whereas S together with other macronutrients strongly indicates deficiencies for forest growth and health.ConclusionsAfter 25 years of reduced S deposition, S nutrition became low for Norway spruce trees in Saxony, whereas soil parent material determines the overall tree nutritional status with respect to other nutrients. As such, no difference between sites with historical high, low or no S deposition was found. Further studies should focus on the mineralization of organic S in the topsoil to understand if S is effectively recycled within the forest ecosystem and on the effect of other diminishing nutrients such as Mg and P.

Thirty Years of Research on Ecosystem Services: The Socio-Economic Role of Forest Visits and Foraging in Enhancing Human Well-Being

This paper examines the socio-economic significance of forest visits and the collection of forest berries and mushrooms (FBMs) in the Czech Republic, emphasising their role in enhancing human well-being and contributing to regional economies. Over a 30-year period, data were collected on the quantities and economic values of FBMs, alongside the intensity of forest visits by the Czech population. This study incorporates a detailed analysis of time series data on FBM collection, exploring trends and fluctuations in the harvested quantities and their economic value. A Lorenz curve analysis reveals significant disparities in the distribution of economic benefits, with a small segment of the population accounting for the majority of the FBM-derived value. Additionally, the research investigates the impact of forest visitation on well-being at the regional level, highlighting the relationship between forest access, visitation intensity, and public health benefits. This study also examines visitors’ expectations, motivations, and perceptions regarding an ideal forest for visitation, providing recommendations for effective marketing strategies. Furthermore, the study explores the contribution of FBMs to net income across different regions, demonstrating substantial regional variation in their economic importance. Notably, the analysis shows that the value of FBMs represents approximately 37% of the net income generated by traditional forestry activities, underscoring its significant economic potential. The findings emphasise the potential of territorial marketing strategies to enhance well-being, particularly in economically disadvantaged regions, and advocate for sustainable forest management practices to protect these valuable resources and ensure equitable access to the benefits provided by forest ecosystems.

A bibliometric analysis of 100 years of research on Himalayan cedar: research trends, gaps, and future implications

Himalayan Cedar (Cedrus deodara), a member of the family Pinaceae is well-known for its ecological, economic, and cultural significance. It is native to the Western Himalayan region and listed as Least Concern in the IUCN list of threatened species. In the present study, a bibliometric analysis of more than a hundred years of research on C. deodara is carried out. Total 616 documents published from 1916 to 2024 were retrieved from the Scopus database and analyzed using biblioshiny and VoS viewer. A comprehensive overview of publication trends, country-wise publications, bibliographic coupling, citation analysis, keyword analysis, and collaborative research networks are presented. The research findings revealed that publications have increased significantly in recent decades and primarily multidisciplinary. Forest ecology, pharmacology, phytochemistry, climate change, environmental science, and taxonomy were among the major thrust areas. However, recent studies are mostly focused on carbon stock, biomass, dendrochronology, and climate change. Out of the 362 publication sources, Bradford’s law identified six journals as core sources for publication. Lotka’ law revealed that only 8% of authors have published more than two documents on C. deodara. The present study provides a comprehensive evaluation and visualization of C. deodara based bibliometric research carried out during the past 100 years. Further, the study provides collective information and a research framework for scholars, the general public, and decision-makers by identifying research gaps and future research areas.

Value Assessment and Prediction of Regulating Ecosystem Services in Hainan Tropical Rainforest National Park, China

Ecosystem services serve as a bridge between the ecological environment and human society. The quantitative analysis and forecasting of ecosystem services can provide references for regional eco-environmental assessments and land-use planning for the future. In this study, taking Hainan Tropical Rainforest National Park (HTRNP) as an example, the value of regulating ecosystem services (RESs) in 2020 was assessed via ArcGIS 10.1 and the InVEST 3.5 model, and the per-unit value of RESs was calculated for different LULC types. In addition, in accordance with the Overall Planning for HTRNP and the objective of optimizing RESs, the value of RESs in short-term (to 2030) and long-term (to 2050) scenarios was forecast via a linear programming model. The results are as follows: (1) The RES value of HTRNP in 2020 was CNY 2090.67 × 108, with climate regulation accounting for the largest proportion; the spatial distribution of RESs in the eastern and central areas was higher than that in the western area, but different indicators of RESs differed in their spatial patterns in varied geographic units. (2) The natural forest ecosystem in HTRNP accounts for 76.94% of the total area but 84.82% of the total value of RESs. The per-unit value is ranked from highest to lowest as follows: montane rainforests > wetlands > lowland rainforests > lowland secondary rainforests > tropical coniferous forests > deciduous monsoon rainforests > tropical cloud forests > shrub forests > timber forests > economic forests > rubber forests > grasslands > farmlands > settlements. (3) In the short-term scenario, the value of RESs is CNY 2216.64 × 108, an increase of CNY 118.97 × 108 compared to 2020, with an increase rate of 5.67%. In the long-term scenario, the value of RESs is CNY 2472.48 × 108, an increase of CNY 374.81 × 108 compared to 2020, with an increase rate of 17.87%. The results reveal the significance of ecosystem services in the national park and can inform more targeted and scientifically sound decision-making in the future.

Rising forest exposure and fire severity from climate warming amplify tree cover losses from wildfire in California

Abstract Warmer temperatures and severe drought are driving increases in wildfire activity in the western United States, threatening forest ecosystems. However, identifying the influence of fire severity on tree cover loss (TCL) is challenging using commonly used categorical metrics. In this study, we quantify regional trends in wildfire-driven TCL as the product of annual burned area, average forest exposure (pre-fire tree cover), and average fire severity (relative loss of tree cover). We quantified these trends with Landsat-based 30 m resolution fire and tree cover datasets for California wildfires from 1986–2021. Rates of TCL rose faster than trends in burned area, with the magnitude of tree cover area loss per unit of area burned increasing by 70% from 0.20 ± 0.05 during 1986–1996 to 0.34 ± 0.10 during 2011–2021. Forest exposure (pre-fire tree cover) within fires increased by 41% from a decadal mean of 23.4% ± 5.5% (1986–1996) to 33.1% ± 7.8% (2011–2021). Increasing forest exposure is associated with a recent expansion of fires in dense northern forests. Concurrently, fire severity (relative TCL) rose by 30% from a decadal mean of 50.4% ± 7.2% during 1986–1996 to 65.6% ± 6.5% during 2011–2021. We developed and applied a simple conceptual framework to quantify the combined effect of wildfires affecting denser forests and burning more severely. The combined effect of these two processes contributed to nearly half (47%) of the TCL since 1986, highlighting that recent changes in burned areas alone cannot explain observed tree cover trends. Linear regression analysis revealed that warmer summers and drier winters were significant drivers of increasing forest exposure, fire severity, and burned area (R 2 from 0.54 to 0.80, p ⩽ 0.001), particularly in the northern forests. Climate extremes had a disproportionate impact on dense forests that were once more resistant to wildfire but now face risks from a shifting wildfire regime.

Estimating Carbon Stock in Unmanaged Forests Using Field Data and Remote Sensing

Unmanaged forest ecosystems play a critical role in addressing the ongoing climate and biodiversity crises. As there is no commercial interest in monitoring the health and development of such inaccessible habitats, low-cost assessment approaches are needed. We used a method combining RGB imagery acquired using an Unmanned Aerial Vehicle (UAV), Sentinel-2 data, and field surveys to determine the carbon stock of an unmanaged forest in the UNESCO World Heritage Site wilderness area Dürrenstein-Lassingtal in Austria. The entry-level consumer drone (DJI Mavic Mini) and freely available Sentinel-2 multispectral datasets were used for the evaluation. We merged the Sentinel-2 derived vegetation index NDVI with aerial photogrammetry data and used an orthomosaic and a Digital Surface Model (DSM) to map the extent of woodland in the study area. The Random Forest (RF) machine learning (ML) algorithm was used to classify land cover. Based on the acquired field data, the average carbon stock per hectare of forest was determined to be 371.423 ± 51.106 t of CO2 and applied to the ML-generated class Forest. An overall accuracy of 80.8% with a Cohen’s kappa value of 0.74 was achieved for the land cover classification, while the carbon stock of the living above-ground biomass (AGB) was estimated with an accuracy within 5.9% of field measurements. The proposed approach demonstrated that the combination of low-cost remote sensing data and field work can predict above-ground biomass with high accuracy. The results and the estimation error distribution highlight the importance of accurate field data.

Mycolichenological portrait of alder forest: alpha diversity revealed in 1ha plot in the Samursky National Park (Republic of Dagestan, Russia)

Aim. Xylobiont fungi and lichens determine the sustainability of forest ecosystems, but their species richness and taxonomic diversity depend on the forest type and the degree of its disturbance. Alder forests, characterised by a specific set of ecological conditions, represent poorly studied habitats in terms of myco‐ and lichenobiota. The aim of this work was to determine the species composition of aphyllophoroid fungi and epiphytic lichens on a 1 ha sample plot in a lowland floodplain forest dominated by Alnus glutinosa in the Delta Samura area of the Samursky National Park.The authors collected basidiomata of lignicolous fungi and lichen specimens on a sample plot of 1 ha during field studies. The surveyed forest area is represented by a community dominated by Alnus glutinosa and lianas. The material was identified using light microscopy techniques and a standard set of chemical reactions.Thirty‐three species of aphyllophoroid fungi (Basidiomycota) and 53 species of lichens and allied fungi (Ascomycota) were identified. Among them, 16 species (48 %) of aphyllophoroid fungi were recorded for the first time for the Samursky National Park, including six species revealed for the first time for the Republic of Dagestan, of which three species (Donkia pulcherrima, Phanerochaete cumulodentata and Sertulicium granuliferum) were new to the Northern Caucasus. Lichen species Arthothelium ruanum, Bacidia arceutina and Graphis pulverulenta are listed for the first time for the Republic of Dagestan. At the same time, 21 species of lichenized fungi were recorded for the first time on Alnus glutinosa within the region.The taxonomical structure of aphyllophoroid fungi revealed reflects the spring period of basidiomata‐based field study. The predominance of corticioid fungi and revealing hydnoid species among morphological groups may be indicative of the generally wetter habitats of alder forests in comparison to other forest types distributed in the studied area. Most of species were recorded on dead wood of Alnus glutinosa as the main forest‐forming tree. At the same time, each of other substrates (Carpinus betulus and Corylus avellana) turned out to be the habitat of species new to the region. The group of fungal species developing on large‐scale substrate units, represented by fallen trunks, was the most prevalent and is to be considered as more vulnarable in a case of anthropogenical habitat disturbance. The majority of epiphytic lichens discovered on alder are not specific to this woody substrate, except for single findings. These species belong to epiphytes inhabiting the Samur forest, the core of the lichenobiota of which is composed of thermophilous lichens of lowland deciduous forests. In our opinion, the relict character of the forest, which is an isolated and rather small forest massif with relatively homogeneous climatic conditions, causes a high similarity between the species composition of lichens revealed in the surveyed sample plot with Alnus glutinosa and previously studied plots dominated by Carpinus betulus, Populus alba, and Quercus robur.

Potential and investment attractiveness of improved forestry projects under increasing climatic challenges

The aim is to justify the potential and provide an assessment of the effectiveness of investing in forest climate projects for improved forestry.A systematic approach was used for a comprehensive, structured and dynamic study of the potential of project activities (forest‐climatic projects) to improve forest productivity. The investment efficiency of forest‐climatic projects on improved forestry is determined taking into account the life cycle of project solutions. To conduct an express assessment of investment attractiveness of forest‐climatic projects, the coefficient characterizing the efficiency of investment for the produce of carbon units was used.It has been revealed that the regions of the Northwestern, Ural and Siberian Federal Districts have the greatest potential of areas of plots (over 2 million ha) for the realization of forest‐climatic projects on improved forestry. It has been shown that for the implementation of forest‐climatic projects on improved forestry in the conditions of the Central forest‐steppe per 1 ha investments of up to 100 thousand rubles are required. For climatic projects on improved forestry, the minimum investment per unit area will be from 97–111 thousand rubles per 1 ha, taking into account the life cycle of the project.The actual practice‐oriented task in the field of forestry has been solved. It consisted in substantiating the investment attractiveness of natural solutions aimed at increasing the carbon depositing functions of forest ecosystems. Calculated potential of areas for the implementation of forest‐climatic projects on improved forestry is an important tool for territorial planning and ensuring sustainable development of regional systems.

Accessing the Trail, Interpreting the Forest

The Stephen F. Austin Experimental Forest is the site of the first ADA-compliant US Forest Service project in Texas. Offering information about the history of forest management alongside information on Pineywoods ecosystems, the interpretive trail raises questions about how access is framed across “natural” and “built” environments as well as how distinctions between nature and culture operate within US environmental imaginaries. This article draws on feminist, posthumanist, and disability studies to conduct a close reading of the interpretive trail as text. It tracks the trail’s approach to disability access as well as its presentation of forest ecology, analyzing how the ableist logic of capitalist commodification underwrites the management of multispecies actants in the woods. I read against the grain of the trail in search of feminist, crip, posthumanist configurations of interdependence and more fluid human–nature boundaries. I argue that cripping the Austin requires questioning the unevenness of disability access as well as the utilitarian ideas of nature presented on the trail while also imagining how we might access and relate to this postindustrial forest otherwise.

Carbon Stock Estimation of Poplar Plantations Based on Additive Biomass Models

Accurate estimation of biomass and carbon stocks in forest ecosystems is critical for understanding their roles in carbon sequestration and climate change mitigation. Currently, the development of stand biomass models and carbon stock estimation at the regional scale has emerged as a prominent research priority. In this study, 225 Populus spp. (poplar) trees in Shandong Province, China, were destructively sampled to obtain the biomass of their components. Two models (MS1 and MS2) were developed using allometric equations and the seemingly unrelated regression (SUR) method to ensure additive properties across tree components. The model evaluation employed the leave-one-out jackknife (LOO) method, considering statistics such as adjusted R-squared (Ra2), root mean square error (RMSE), mean absolute percent error (MAPE), and mean absolute error (MAE). The results from our models demonstrated high accuracy, with MS2 slightly outperforming MS1 after incorporating tree height as an independent variable. The models reliably estimated component-specific biomass and carbon stocks, with distinct variations observed in the carbon content among foliage (47.14 ± 2.07%), branches (47.26 ± 2.48%), stems (47.67 ± 2.21%), and roots (46.37 ± 2.78%). Carbon stocks in poplar plantations increased with the diameter class, ranging from 5 to 35 cm and correspondingly from 3.670 to 172.491 Mg C ha−1. As the diameter class increases, the carbon allocation strategy of poplars aligns with the CSR strategy, transitioning from prioritizing growth competition to emphasizing self-stabilization. Our research proposes a robust framework for assessing biomass and carbon stocks in poplar plantations, which is essential for evidence-based forest management strategies.

Depth-dependent effects of forest diversification on soil functionality and microbial community characteristics in subtropical forests

Soil microbes are critical to the maintenance of forest ecosystem function and stability. Forest diversification, such as monocultures versus mixed forests stands, can strongly influence microbial community patterns and processes, as well as their role in soil ecosystem multifunctionality, such as in subtropical forest ecosystems. However, less is known about these patterns and processes vary with soil depth. Here, we investigated the results of an eight-year forest diversification field experiment comparing the soil ecosystem multifunctionality, bacterial and fungal community assembly, and network patterns in mixed versus monoculture plantations along vertical profiles (0–80 cm depth) in a subtropical region. We found that the introduction of broadleaf trees in coniferous monocultures led to enhanced synergies between multiple functions, thus improving soil multifunctionality. The effects of mixed plantations on the functional potential in top soils were greater than in deep soils, especially for carbon degradation genes (apu, xylA, cex, and glx). Microbial community assembly in the top layer, particularly in mixed plantations, was dominated by stochastic processes, whereas deterministic were more important in the deep layer. Soil microbial network complexity and stability were higher in the top layer of mixed plantations, but in the deep layer was monoculture. Interestingly, the changes in microbial communities and multifunctionality in the top layer were mainly related to variation in nutrients, whereas those in the deep were more influenced by soil moisture. Overall, we reveal positive effects of mixed forest stands on soil microbial characteristics and functionality compared to that of monocultures. Our findings highlighted the importance of enhancing functional diversity through the promotion of tree species diversity, and managers can better develop forest management strategies to promote soil health under global change scenarios.

Microbial community composition and co-occurrence network analysis of the rhizosphere soil of the main constructive tree species in Helan Mountain of Northwest China

To understand the microbial diversity and community composition within the main constructive tree species, Picea crassifolia, Betula platyphylla, and Pinus tabuliformis, in Helan Mountain and their response to changes in soil physicochemical factors, a high throughput sequencing technology was used to analyze the bacterial and fungal diversity and community structure. RDA (Redundancy Analysis) and Pearson correlation analysis were used to explore the influence of soil physicochemical factors on microbial community construction, and co-occurrence network analysis was conducted on the microbial communities. The results showed that the fungal and bacterial diversity was highest in B. platyphylla, and lowest in P. crassifolia. Additionally, the fungal/bacterial richness was greatest in the rhizosphere soils of P. tabuliformis and B. platyphylla. RDA and Pearson correlation analysis revealed that NN (nitrate nitrogen) and AP (available phosphorus) were the main determining factors of the bacterial community, while NN and SOC (soil water content) were the main determining factors of the fungal community. Pearson correlation analysis between soil physicochemical factors and the alpha diversity of the microbial communities revealed a significant positive correlation between pH and the bacterial and fungal diversity, while SOC, TN (total nitrogen), AP, and AN (available nitrogen) were significantly negatively correlated with the bacterial and fungal diversity. Co-occurrence network analysis revealed that the soil bacterial communities exhibit richer network nodes, edges, greater diversity, and greater network connectivity. Indicating that bacterial communities exhibit more complex and stable interaction patterns in soil. This study reveals the complex interactive relationship between microbial communities and soil physicochemical factors in forest ecosystems. By analyzing the response of rhizosphere microbial communities of major tree species in Helan Mountain to nutrient dynamics and pH changes, we can deepen our understanding of the role of microorganisms in regulating ecosystem functions and provide theoretical basis for soil improvement and ecological restoration strategies.