A Comparison of the Impact of Latitude on the Root-Shoot Ratio of Natural and Planted Forests

The forest root-shoot ratio (R/S) is an important indicator of the structure and function of forest ecosystems. It reflects the adaptive strategies of plants to environmental changes, and its pattern of change along the latitudinal gradient is of great significance for understanding the response of forest ecosystems to environmental changes. Although numerous studies have addressed the relationship between climate, soil conditions, and the ratio of below-ground biomass to above-ground biomass (R/S) at the local scale, the pattern of R/S variations along the latitudinal gradient in different types of forests, as well as the dominant factors, remain unclear. This study, based on field surveys and literature collected from 2005 to 2020 on 384 planted forests and 541 natural forests in China, investigates the patterns of forest root-shoot ratio variation along latitudinal gradients in planted and natural forests. The study demonstrated a positive correlation between forest R/S ratio and increasing latitudinal gradients across different forest types, including planted and natural forests (p < 0.001). The results demonstrated a negative correlation between R/S in both planted and natural forests and mean annual temperature, annual precipitation and soil phosphorus content. Conversely, a positive correlation was observed between R/S and soil nitrogen content and soil pH. It can be observed that plantation forests are more susceptible to alterations in forest factors than natural forests. Latitudinal patterns can not only directly affect the R/S of planted and natural forests, but also affect forest R/S by influencing climate and forest factors and the interactions of the factors together. Our study distinguishes the pattern of R/S changes along the latitudinal gradient in planted and natural forests and its influencing factors. These findings are important for understanding the pattern changes in different forest ecosystems and provide a theoretical basis for efficiently guiding forest management.