Influence of stand and environmental factors on forest productivity of Platycladus orientalis plantations in Beijing’s mountainous areas

Diversified soil microbiomes are the key drivers of carbon fixation and plant residue decomposition in forest ecosystems. Revealing the elevation patterns of soil microbial carbon cycling in forests is essential for utilization of forest ecological resources. However, the soil microbial diversity and carbon cycle processes in Platycladus orientalis plantations across different elevations are still unclear. Here, we established a gradient with three elevations (118 m, 300 m, and 505 m) on the Beijing Ming Dynasty Tombs Forest Farm, which is located in Changping District, Beijing. The metagenomics method was applied to study the soil microbiome, with a special focus on the carbon cycle process at each elevation. We found the diversity and composition of the soil microbiomes significantly varied across the elevation gradients. The structure of bacteria and archaea was mainly driven by soil total potassium, pH and NH4+, but the eukaryota had no significant relationship with the environmental factors. The relative abundance of genes involved in microbial carbon fixation and decomposition of organic carbon were also significantly impacted by elevation, with the former showing increasing, u-shaped, or hump trends with increasing elevation, but the latter only showing hump trends. The rTCA cycle and 3-hydroxypropionate pathway were the dominant carbon fixation pathways in the Platycladus orientalis plantations. The elevation gradient shaped the microbial decomposition of plant-derived organic carbon by changing soil properties and, furthermore, led to soil organic carbon stock losses. These findings increase our understanding of soil microbial diversity and the carbon cycle across different elevations and provide a theoretical basis for the utilization of forest ecological resources to promote carbon sequestration.

Section: Introductionmentioning

confidence: 99%

Elevation Shapes Soil Microbial Diversity and Carbon Cycling in Platycladus orientalis Plantations

Zhang,

Yuan,

et al. 2024

Applying Specific Habitat Indicators to Study Asteraceae Species Diversity Patterns in Mountainous Area of Beijing, China

Zhang,

Qi,

Zhao

et al. 2024

The distribution pattern and influencing factors of specific species diversity play a crucial role in decision-making for biodiversity conservation. Identifying suitable regional habitat indicators to assess specific species diversity patterns is a global focus topic. A total of 112 sample plots were surveyed to investigate the relationship between Asteraceae species diversity and topography, soil nutrients, and stand factors, using a Structural Equation Model (SEM). Additionally, the Maxent model was utilized to predict the distribution pattern of Asteraceae species diversity in response to specific habitat factors. The findings revealed that soil nutrients, topography, and canopy closure had different impacts on Asteraceae species diversity, with soil nutrients showing the highest relative coefficient, followed by topography and canopy closure. The elevation and slope gradient were identified as direct and indirect influences on Asteraceae species diversity. The contribution rate of potential environmental variables on the Asteraceae species diversity was ranked as follows: STN (29.7%) > SOM (28.5%) > slope (8.5%) > Ele (8.1%). Asteraceae species diversity was found to be abundant in the locations with SOM (>27 g/kg), STN (>1.8 g/kg), Ele (165–333 m), and slopes (5–12 degrees). Soil nutrient content serves as a key indicator for assessing the abundance of Asteraceae species diversity and should be considered in biodiversity conservation.

Response of Fuel Characteristics, Potential Fire Behavior, and Understory Vegetation Diversity to Thinning in Platycladus orientalis Forest in Beijing, China

Gao,

Chen,

Suo

et al. 2024

Objective: Active fuel management operations, such as thinning, can minimize extreme wildfire conditions while preserving ecosystem services, including maintaining understory vegetation diversity. However, the appropriate thinning intensity for balancing the above two objectives has not been sufficiently studied. Methods: This study was conducted to assess the impact of various thinning intensities (light thinning, LT, 15%; moderate thinning, MT, 35%; heavy thinning, HT, 50%; and control treatment, CK) on fuel characteristics, potential fire behavior, and understory vegetation biodiversity in Platycladus orientalis forest in Beijing using a combination of field measurements and fire behavior simulations (BehavePlus 6.0.0). Results: A significant reduction in surface and canopy fuel loads with increasing thinning intensity, notably reducing CBD to below 0.1 kg/m3 under moderate thinning, effectively prevented the occurrence of active crown fires, even under extreme weather conditions. Additionally, moderate thinning enhanced understory species diversity, yielding the highest species diversity index compared to other treatments. Conclusions: These findings suggest that moderate thinning (35%) offers an optimal balance, substantially reducing the occurrence of active crown fires while promoting biodiversity. Therefore, it is recommended to carry out moderate thinning in the study area. Forest managers can leverage this information to devise technical strategies that simultaneously meet fire prevention objectives and enhance understory vegetation species diversity in areas suitable for thinning-only treatments.