Developing accurate activity data on tree biomass using remote sensing tools such as LiDAR and drone-mounted sensors is essential for improving carbon accounting in the agricultural sector. However, direct biomass measurements of perennial fruit trees remain limited, especially for validating remote sensing estimates. This study evaluates the potential of terrestrial laser scanning (TLS) and drone-mounted RGB sensors (Drone_RGB) for estimating biomass in two major perennial crops in South Korea: apple (‘Fuji’/M.9) and citrus (‘Miyagawa-wase’). Trees of different ages were destructively sampled for biomass measurement, while volume, height, and crown area data were collected via TLS and Drone_RGB. Regression analyses were performed, and the model accuracy was assessed using R², RMSE, and bias. The TLS-derived volume showed strong predictive power for biomass (R² = 0.704 for apple, 0.865 for citrus), while the crown area obtained using both sensors showed poor fit (R² ≤ 0.7). Aboveground biomass was reasonably estimated (R² = 0.725–0.865), but belowground biomass showed very low predictability (R² < 0.02). Although limited in scale, this study provides empirical evidence to support the development of remote sensing-based biomass estimation methods and may contribute to improving national greenhouse gas inventories by refining emission/removal factors for perennial fruit crops.

Previous studies on island biogeography theory have limitations in that they are mostly focused on total plant species and the landscape factors of the islands. Our study was conducted to overcome these limitations by dividing the plants into five growth forms and analyzing climate and landscape factors on inhabited islands, uninhabited islands, and overall. This was achieved using plant data from 578 islands of an archipelago in South Korea. To test the relationship between the species richness of each growth form and environmental factors, we performed ordinary least squares regressions and multi-model inference tests. The results showed that the island area had the largest influence on species richness of all growth forms in overall and uninhabited islands. Moreover, climate factors, in addition to island area, significantly affected species richness of all growth forms on inhabited islands. However, the effect and of isolation-related landscape factors (i.e., distance from the mainland and structural connectivity) were different among growth forms and island categories. Our study reveals that there are differences in the effects of environmental factors on the growth forms of plants among island categories. This suggests that biodiversity management and conservation strategies should be applied separately to different growth forms and islands.

The elevational patterns of soil microbial and nematodes diversity (SMND) and the determinants remain controversial. Moreover, how the SMND are modified simultaneously with an elevational gradient has not yet been established. In this study, we investigated the elevational patterns of the SMND and the relative importance among/within tree factors (i.e., tree diversity, identity, and quantity) and environmental factors (i.e., climate and soil) on the SMND. For this purpose, we analyzed datasets from 27 plots across nine elevation bands in the temperate forests of Mt. Gariwang, South Korea. We performed multimodel inference tests and subsequently conducted a variance partitioning to determine the most prominent factors controlling each SMND and compare the relative contribution of the trees and environmental effects. Our results revealed that bacterial and fungal diversity decreased along the elevation gradient. However, nematode diversity did not change significantly, indicating that site-specific environmental conditions may be more influential than the elevation per se. Moreover, this indicates that bacterial diversity was affected by the pH and functional dispersion of the leaf size, and that fungal diversity was governed only by the pH. However, nematode diversity was driven by aboveground biomass, ammonium-nitrogen, and tree size diversity. In summary, the soil microbial diversity was more strongly controlled by the environmental factors, whereas the tree factors were more important for nematodes. Our results show that the elevational patterns and determinants of SMND differed among the taxonomic groups in the common micro-food web. These findings provide new insights into the factors controlling the SMND in a temperate forest and expand the local knowledge of soil biodiversity which is necessary for promoting its mainstreaming. Thus, our results contribute to establishing a basis for more targeted and effective biodiversity conservation and management practices in forest ecosystems.

Forest restoration sites have a critical role in the maintenance and improvement of forest ecosystem health and resilience, as well as increasing carbon storage capacity. However, previous studies on forest restoration sites have primarily focused on monitoring vegetation changes and investigating changes in carbon storage (e.g., aboveground biomass). Research on identifying the controlling drivers of aboveground biomass (AGB) between/among forest types according to stand age within restoration sites remains limited. Our study analyzed data from a total of 149 plots in forest restoration sites in South Korea, comprising 57 coniferous forest plots (38.3%) and 92 broadleaved forest plots (61.7%). This study employed a piecewise structural equation model to determine the main biotic (i.e., stand structural diversity, species diversity, functional diversity, and tree identity) and abiotic drivers (i.e., topographic, climate factors driver, stand age, and soil properties) influencing AGB in each forest type. The results revealed that stand structural diversity was the most critical driver of AGB across all forest types, highlighting the importance of structural complexity in early stage restoration. Specifically, in coniferous forests, stand structural diversity (DBH STD) and tree identity (CWM WD) were more influential, whereas in broadleaved forests, SR and climatic conditions played a greater role. Therefore, our findings provide empirical evidence for understanding AGB dynamics in early stage forest restoration sites and may help inform the development of management strategies for each forest type and early restoration planning in similar ecosystems.

Enhancing forest biodiversity and carbon sinks in the face of climate change is a high priority on the global agenda. The aim of our study was to explore the feasibility and potential of enhancing biodiversity and stand biomass productivity, which are strongly linked to forest ecosystem functioning and services in temperate forests. Based on data from the 5th to 7th National Forest Inventory of South Korea, 1760 natural forest plots (0.16 ha) were used, of which 344 plots belonged to conifer stands, 711 plots belonged to broadleaved stands, and 705 plots belonged to mixed stands. Forest succession-related factor (i.e., stand age), and abiotic (i.e., climatic and topographic conditions, and soil properties) and biotic drivers (i.e., species diversity, functional trait diversity, functional trait identity, and stand structural diversity) were jointly included as independent variables in an integrated model to explain variations in stand biomass productivity. In order to reveal the key drivers and relationships that regulate stand biomass productivity across forest stand types, we applied a multi-model averaging approach and piecewise structural equation modelling (pSEM). As a key finding, across all forest stand types, forest stand age-induced tree size inequality (i.e., DBH STD) in all forest stand types commonly increased stand biomass productivity, showing strong positive standardized effects (β > 0.5, p < 0.001). We also found that the functional trait identities controlling stand biomass productivity within each forest stand type differed according to their functional traits of dominant species, and that these mechanisms were controlled directly or indirectly by environmental conditions. Our research suggests that appropriate forest management plans should be developed in accordance with environmental gradients to simultaneously promote biodiversity and stand biomass productivity in different forest stand types.

Forest soils play a critical role in carbon sequestration and nutrient cycling by storing large amounts of soil organic matter (SOM). However, the integrated associations linking aboveground resource properties and belowground microbial processes influencing SOM dynamics remain poorly understood. In this observational, cross-sectional study, we analyzed 84 plots across six forest types at Mt. Gariwang, South Korea, to evaluate the relative importance of resource quality and resource quantity in relation to SOM dynamics. Total organic carbon (TOC), total nitrogen (TN), and the C:N ratio were used as indicators of SOM dynamics. Resource quality was represented by species richness (SR) and functional dispersion (FDis) as indirect proxies, whereas resource quantity was represented by aboveground biomass (AGB) and diameter at breast height diversity (DBH diversity). We also evaluated whether fungal and bacterial ASV richness were statistically linked to the relationships between aboveground resource properties and SOM dynamics. Functional dispersion (FDis) was negatively associated with TOC (β = −0.28) and the C:N ratio (β = −0.51), whereas AGB showed no significant relationship with any SOM indicator. In contrast, SR was positively associated with Fungal ASV richness (β = 0.37), which was in turn positively linked to TOC (β = 0.43) and TN (β = 0.56) accumulation, suggesting an indirect statistical pathway consistent with fungi acting as a biological link between aboveground biodiversity and belowground carbon and nitrogen storage. These findings indicate that resource quality indicators showed divergent associations with SOM dynamics: a negative direct pathway via FDis and a positive indirect pathway via SR and fungal ASV richness, and that, overall, resource quality was more consistently associated with SOM dynamics than resource quantity. Our study provides new insights into the associations linking aboveground vegetation and belowground microbial communities and offers a scientific basis for biodiversity-based forest management to enhance long-term soil carbon sequestration.