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Phytolith-occluded carbon (PhytOC), a promising long-term biogeochemical carbon sequestration mode, plays a crucial role in the global carbon cycle and the regulation of atmospheric CO2. Previous studies mostly focused on the estimation of the content and storage of PhytOC, while it remains unclear about how the management practices affect the PhytOC content and whether it varies with stand age. Moso bamboo (Phyllostachys heterocycla var. pubescens) has a great potential in carbon sequestration and is rich in PhytOC. Here, we selected four management treatments, including control (CK), compound fertilization (CF), silicon (Si) fertilization (SiF) (monosilicic acid can form phytoliths through silicification), and cut to investigate the variation of phytoliths and PhytOC contents in soil, leaves, and litters, and their storage in Moso bamboo forests. In soil, the SiF fertilizer treatment significantly (P < 0.05) increased phytolith content, PhytOC content, and storage compared to CK, while there were no significant differences between the treatments of CF and cut. In leaf, compared with CK, phytolith content of the second-degree leaves under SiF and the first-degree leaves under cut treatment significantly increased, and the three treatments significantly increased PhytOC storage for leaves with three age classes. In litter, the phytolith and PhytOC contents under the three treatments were not significantly different from that under the CK treatment. The PhytOC storage increased by 19.33% under SiF treatment, but significantly decreased by 40.63% under the CF treatment. For the entire Moso bamboo forest ecosystems, PhytOC storage of all the three management treatments increased compared with CK, with the largest increase by 102% under the SiF treatment. The effects of management practices on the accumulation of PhytOC varied with age. Our study implied that Si fertilization has a greater potential to significantly promote the capacity of sequestration of carbon in Moso bamboo forests.

<p>Forest ecosystem has a high carbon sequestration capacity and plays a crucial role in maintaining global carbon balance and climate change. Phytolith-occluded carbon (PhytOC), a promising long-term biogeochemical carbon sequestration mechanism, has attracted more attentions in the global carbon cycle and the regulation of atmospheric CO<sub>2</sub>. Therefore, it is of practical significance to investigate the PhytOC accumulation in forest ecosystems. Previous studies have mostly focused on the estimation of the content and storage of PhytOC, while there were still few studies on how the management practices affect the PhytOC content. Here, this study focused on the effects of four management practices (compound fertilization, silicon fertilization, cut and control) on the increase of phytolith and PhytOC in Moso bamboo forests. We found that silicon fertilization had a greater potential to significantly promote the capacity of carbon sequestration in Moso bamboo forests. this finding positively corresponds recent studies that the application of silicon fertilizers (e.g., biochar) increase the Si uptake<strong><sup>1</sup></strong> to promote phytolith accumulation and its PhytOC sequestration in the plant-soil system<strong><sup>2</sup></strong>. Of course, the above-mentioned document<strong><sup>2</sup></strong> also had their own shortcomings, i.e., the experimental research time was not long, lacking long-term follow-up trial and the bamboo forest parts were also limited, so that the test results lack certain reliability. We have set up a long-term experiment plot to study the effects of silicon fertilizer on the formation and stability of phytolith and PhytOC in Moso bamboo forests. But anyway, different forest management practices, especially the application of high-efficiency silicon-rich fertilizers<strong><sup>1</sup></strong>, may be an effective way to increase the phytolith and PhytOC storage in forest ecosystems, and thereby improve the long-term CO<sub>2 </sub>sequestration capacity of forest ecosystems. Research in this study provides a good "forest plan" to achieve their national voluntary emission reduction commitments and achieves carbon neutrality goals for all over the world.</p><p>Refences:</p><p><sup>1</sup>Li et al., 2019. Plant and soil, 438(1-2), pp.187-203.</p><p><sup>2</sup>Huang et al., 2020, Science of The Total Environment, 715, p.136846.</p>