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

Abstract

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.

Comparison of Planted Pine versus Natural Mix Forests in Nepal

“…In contrast, other forests in Nepal typically exhibit a reversed J-shape DBH distribution, indicating a continuous population structure [12,17]. This homogenous stand structure impedes regeneration and tree size diversity, compromising sustainability [7]. In plantation forests, biomass stock is expected to decrease significantly over time due to the bell-shaped DBH distribution and challenges such as minimal regeneration, acidic Pinus needles, and frequent fires hindering natural regeneration.…”

“…Realizing the fact that forest vegetation and forest soils are viable sinks of atmospheric carbon and can significantly mitigate global climate change [2][3][4][5], regardless of their mode of regeneration, the concern of global communities regarding forest ecosystems has increased. Additionally, these terrestrial ecosystems offer numerous benefits, such as improving soil fertility, ecosystems, and biodiversity, which in turn lead to a series of other positive outcomes [3,[5][6][7] benefitting people and the planet. A large chunk of global forests are natural; however, their conversion to arable land and other types of land uses has resulted in the shrinkage of these areas day by day [1,8].…”