Soil Biodiversity as Affected by Different Thinning Intensities in a Pinus laricio Stand of Calabrian Apennine, South Italy

Integrating seasonal dynamics and human impact on microbial biomass carbon across deep soil profiles in tropical Sal forest of Achanakmar-Amarkantak Biosphere Reserve, India

Forest soil is crucial in climate change mitigation, food security, and biogeochemical nutrient cycling. Mixed Sal forests enhance soil organic matter, improve nutrient availability, and regulate pH dynamics. However, anthropogenic disturbances, including deforestation and land-use changes, significantly alter forest cover, leading to shifts in soil physicochemical and microbial properties. These impacts necessitate rigorous monitoring and comprehensive assessment. Therefore, we investigated the effects of contrasting conditions- closed (no human activities) and open (human interferences) mixed Sal Forest on the vertical and seasonal dynamics of microbial biomass carbon (SMBC). Results revealed that the closed mixed Sal Forest had significantly higher SMBC than the open mixed Sal Forest across the soil profile (D1-D5) with a strong seasonal effect. Closed mixed Sal Forest had 60% higher SMBC in D1 than open mixed Sal Forest while it reduced with depth and 17.1 to 56.7% higher SMBC in the subsurface to bottom-most soil profile (D2-D5). Moreover, SMBC was higher in the monsoon period in both forests. The SMBC reduced by 24.2 to 45.1% in the post-monsoon period while reduction was more intense in the pre-monsoon period (48.1 to 68.2%) compared to the monsoon period under closed mixed Sal Forest. Similarly, the decline was more intense in the open mixed Sal Forest, where SMBC declined 12.1 to 54% in the post-monsoon period and 56.1 to 76.2% in the pre-monsoon period compared to the monsoon period. The study indicates that human interference in mixed Sal forests leads to loss of forest cover, negatively affecting microbiological properties and reducing soil fertility, which weakens the forest's resilience to climate change. Additionally, SMBC exhibits seasonal variations, reflecting responses to environmental conditions. These results underline the need to reduce human disturbances and enhance forest conservation strategies to ensure soil sustainability and ecosystem stability.

Influence of vegetation and soil properties on carbon stocks in Shorea robusta forests under different disturbance regimes

Sal (Shorea robusta) forest ecosystem is among the most carbon-dense terrestrial ecosystems globally, playing a crucial role in climate change mitigation through carbon (C) sequestration in biomass and soil. Disturbances are key factors influencing vegetation diversity and soil nutrient status, which in turn influence biogeochemical cycling and ecosystem functions. To accurately assess the effects of disturbance regimes on carbon stock potential and stability, it is essential to quantify the dynamics of vegetation biomass carbon (VBC) and soil organic carbon (SOC) stocks along with their underlying drivers. However, this information is currently limited, and the mechanisms governing VBC and SOC stock responses to disturbance are poorly understood. Present study investigated the effects of disturbance regimes categorized as no disturbance (ND, <5% tree basal area removal), low disturbance (LD, <20%), moderate disturbance (MD, <50%), and high disturbance (HD, >50%) on carbon stock patterns in sub-tropical deciduous sal forests. It also explored the interdependence between vegetation structure (density, basal area), diversity, and soil properties in influencing VBC and SOC stocks. Greater tree recruitment, vegetation diversity, and soil nutrients were observed under moderate disturbance compared to other regimes. Under-canopy biomass C stocks ranged from ∼46.5 to 182.6 Mg C ha-1, comprising 13.1-65 %, while SOC stock ranged from ∼4.7 to 54.8 Mg C ha-1, contributing 27.4-37.3 % to forest C stocks. Variations in stand structure, diversity, and soil properties influenced by disturbance regimes, promoted structural complexity, and improved nutrient availability and C stocks. Predictive model analysis revealed that variations in VBC and SOC stocks were strongly determined by changes in under-canopy diversity and soil properties, especially soil nutrients (N, P) and microbial biomass. Path analysis indicated that mechanisms influencing VBC and SOC stock dynamics following disturbances differed between under-canopy and canopy vegetation. This study highlights the importance of disturbance regimes in shaping vegetation recovery and soil health, providing a foundation for developing effective management strategies to optimize carbon storage in natural forest ecosystems.

Managing soil to support soil biodiversity in protected areas agroecosystems: a comparison between arable lands, olive groves, and vineyards in the Conero Park (Italy)

Sustainable soil management is essential to conserve soil biodiversity and its provision of vital ecosystem services. The EU Biodiversity Strategy for 2030 highlights the key role of organic farming and land protection in halting biodiversity loss, including edaphic biodiversity. To assess the effectiveness of the proposed measures, a 1-year study was conducted in spring 2022 to determine the soil quality of three organically managed agroecosystems and four sites for each: arable lands, olive groves, and vineyards in the Conero Park, using the arthropod-based Biological Soil Quality Index (QBS-ar) and also considering soil chemical-physical characteristics. Soil microarthropods are sensitive indicators of the impact of agricultural practices on soil quality. Given the diversity of the agronomic practices applied in these agroecosystems, the study aimed to compare the soil quality and identify the system with the least impact on soil biodiversity conservation, with the goal of laying the basis for identifying soil quality benchmarks within each system to be used in monitoring activities in land protected areas. Results showed that organic farming combined with land protection had a positive impact on soil quality. The overall soil quality was excellent, with the highest levels found in arable lands. This is consistent with the intermediate disturbance hypothesis (IDH), which states that slightly disturbed habitats (i.e., arable land with minimum tillage) tend to have higher organism diversity than stable ones. The composition of microarthropod communities in arable land differed from those in stable arboreal crops. Olive groves showed a higher abundance and diversity of microarthropods compared to vineyards, which showed lower values. Promoting the use of QBS-ar, identifying benchmarks for prevalent agroecosystems, and ensuring continuous monitoring of protected areas are thus crucial issues.

Effect of frequent clearcutting on some soil properties, temperatures, and herbaceous vegetation and the potential of their recovery in a short time

Harvesting or degradation of forest ecosystems directly affects the microclimate, causing changes in air and soil temperatures and soil moisture in the forestlands. The objectives of this study were to investigate the effect of frequent clearcutting of forest cover on some selected soil properties, ambient and soil temperatures, soil moisture, and herbaceous vegetation cover and determine their recovery in a short period in the area subject to frequent clearcutting under the powerline corridors (PLCs). The study was conducted in the research forest of Istanbul University-Cerrahpaşa, Faculty of Forestry. The treatment plots were selected from the clearcut area, and control plots were selected from an untouched oak-hornbeam forestland. Soil temperature and moisture and maximum and minimum ambient temperatures were measured in the treatment and control plots between 2020 and 2021 and topsoil sampled between 2019 and 2021. Data were analyzed using analysis of variance (ANOVA) to test the effects of clearcutting on some selected soil properties in the short term after cutting. Clearcutting caused a significant increase in soil bulk density (BD) and a decrease in the soil total porosity (TP), soil hydraulic conductivity (HC), and saturation capacity (SC). Forest cover removal significantly decreased the soil organic matter (SOM) content by 3%, increased average soil temperature by 2.1 °C, and the difference between maximum and minimum temperatures by 8.8 °C. Additionally, clearcutting reduced the average soil moisture from 36 to 35%. The findings revealed that clearcutting negatively affected some hydro-physical soil properties and soil microclimate conditions that may not recover to their previous states within the next few years.

Dynamics of soil bio-physicochemical properties under different disturbance regimes in sal forests in western Himalaya, India

Disturbance is a key factor in controlling vegetation diversity, nutrient influx rate, and biochemical cycling in terrestrial forest ecosystems. Limited studies are available on changes in tree diversity, soil nutrients and enzyme activities in response to different intensities of land disturbances in the Himalayan forests. Present study investigated the impact of varying intensities of disturbances on tree diversity and their relationship with soil physical and bio-chemical properties in sal forests, Western Himalayas. Sites were categorized into four different classes of disturbances, namely, No disturbance (ND), Low disturbance (LD), Moderate disturbance (MD), and High disturbance (HD). Composite samples were collected at two depths (0-15 and 15-30 cm) in each plot to investigate soil physical and biochemical properties. Multivariate analyses were conducted to find relationship between tree vegetation and soil physical and biochemical properties. Soil organic carbon (C_org), total nitrogen (N_ttl), available phosphorous (P_avl), microbial biomass carbon (C_mic), nitrogen (N_mic), phosphorous (P_mic), and enzymes (dehydrogenase (DHA), Urease, acid and alkaline phosphatase) followed the order: MD > ND > LD > HD. Across disturbances, soil physical and biochemical characteristics significantly (p < 0.05) decreased with increasing soil depths. Across the sites, positive correlation was observed among soil microbial biomass, enzymes, C_org, clay, and moisture. Redundancy analysis (RDA) results revealed that species distribution is essential regulator in the variation of prominent soil variables, viz., nutrients (N_ttl and P_avl), C_mic, and DHA across disturbance categories and soil depths. Moreover, variance partitioning analysis (VPA) showed that changes in vegetation composition across disturbance levels explain 13.12 % of the variation in soil biochemical subset higher than soil physicochemical subset. The result illustrated that moderate disturbance increases species composition, soil nutrient properties and microbial activity. These findings would help understand microbial activity and its relationship with disturbances, suggesting site-specific measurements for soil nutrient availability and above-below ground interactions.

Understory vegetation diversity, soil properties and microbial community response to different thinning intensities in Cryptomeria japonica var. sinensis plantations

Introduction

Soil microorganisms are the key factors in elucidating the effects of thinning on tree growth performance, but the effects of vegetation and soil on the species composition and function of soil microorganisms after thinning are still not well elaborated.

Methods

The effects of thinning on understory vegetation diversity, soil physicochemical properties and soil microbial community composition were investigated in a thinning trial plantation of Cryptomeria japonica var. sinensis, including four thinning intensities (control: 0%, LIT: 20%, MIT: 30% and HIT: 40%), and the relationships of the microbial community structure with the understory vegetation diversity and soil properties were assessed.

Results

The results showed that thinning had a greater effect on the diversity of the shrub layer than the herb layer. The soil bulk density and the contents of soil organic matter, total potassium and nitrogen increased with increasing thinning intensities. The Shannon and Chao indices of soil bacteria and fungi were significantly lower in the LIT, MIT and HIT treatments than in the control. Thinning can significantly increase the abundance of Proteobacteria and Actinobacteria, and higher thinning intensities led to a higher relative abundance of Ascomycota and a lower relative abundance of Basidiomycota, Rozellomycota, and Mortierellomycota. Redundancy analysis indicated that soil physicochemical properties rather than understory vegetation diversity were the main drivers of microbial communities, and fungi were more sensitive to soil properties than bacteria. Functional prediction showed that thinning significantly reduced the potential risk of human diseases and plant pathogens, and the nitrogen fixation capacity of bacteria was the highest in the HIT treatment. Thinning significantly increased the relative abundance of cellulolysis and soil saprotrophs in bacteria and fungi.

Conclusion

The findings provide important insights into the effects of thinning on C. japonica var. sinensis plantation ecosystems, which is essential for developing thinning strategies to promote their ecological and economic benefits.