<b>Phosphorus release from rock weathering weakens the linkage between root carbon allocation and land use intensity</b>

Root carbon allocation (RCA) is a key component of the vegetation-soil carbon cycle, playing an important role in mitigating global climate change by regulating the carbon cycle. However, the empirical quantification of how phosphorus release from rock weathering (PR) affects RCA under land use intensity (LUI)control, has not yet been achieved on a global scale. Here, we combined spatial mixed linear effect models and random forest models to elucidate the response changes of global RCA in topsoil (0-30cm) to LUI under different scenarios of PR conditions. The results show that when the LUI exceeded 1.68, PR reversed RCA's positive response to it, and about 50.45% of the global area is highly sensitive to PR. The global increase in RCA under influence of LUI slowed down by 0.104‰ with the participation of PR. It is expected that by the end of this century, under the dual influence of LUI and PR, RCA will reach 1.73-1.79 Pg, and the dual effect may cause RCA to decrease by 0.34‰. Among them, China will have the maximum climate benefit brought by RCA in the future, as high as 16.96 billion USD. This indicates that under the influence of rising global PR and LUI, it will weaken the trend of increasing RCA and its benefit brought about by climate change. We reconciled the conflicting evidence regarding the impact of FP and LUI on RCA across different scales and provides an empirical estimate of RCA's response to FP and LUI, which may help to formulate reasonable ecological restoration measures such as nutrient management and land use plan.