Xiaoyue Zhang, Xiangyin Ni, Petr Heděnec, Kai Yue, Xinyu Wei, Jing Yang, Fuzhong Wu
Vegetation regeneration is a complex process, involving many stages from seeds and seedlings to plant establishment and development. As the first thing the seed contacts on the soil floor, litter could provide nutrients and a relatively stable environment for seed germination. Rapid vegetation regeneration and increased litter production have been predicted under the global greening scenario, but the overall relationship between litter production and vegetation regeneration has not been well addressed.
In this study, we estimate how litter production on a global scale affects each stage of vegetation regeneration (not directly on seeds, detrimental to seedlings but beneficial to plant development) and their drivers, using a synthesis of published studies. We found that seed germination responds positively to changes in soil moisture induced by litter. Although litter generally has a negative effect on the subsequent seedling stage, it can promote seedling survival by alleviating temperature and moisture constraints with increasing elevation. After this vulnerable early stage, litter facilitates plant development, but the impact varies depending on the litter composition and plant type, while the effect on the vegetation community is slight.
Collectively, the present results suggest that litter provides important protection against environmental stresses for early vegetation regeneration, implying that increased litter production would promote a positive cycle of vegetation regeneration under global greening. These findings highlight that the relationship between litter production and vegetation regeneration varies at different stages depending on vegetation and environmental conditions, which could help to develop models accounting for vegetation regeneration responses to ongoing global greening.