Changes in the Diversity of Herbaceous Layer Under Typical Artificial Forests Along an Altitude Gradient in Mount Taishan

The distribution pattern of biodiversity along an elevation gradient in mountain ecosystems has always been a focal point in biodiversity research. As an important component of forest ecosystems, the understory herb layer occupies a significant position in forest succession and plays a crucial role in maintaining the stability of forest ecosystems, protecting biodiversity, and enhancing ecosystem functions. This study comprehensively analyzes the diversity characteristics of plant communities in the understory herb layer of different forest stands and their variation along an elevation gradient through research on typical artificial forest communities in Mount Taishan, elucidating the relationship between plant diversity and community productivity. The results indicate that there are significant differences in the impact of elevation gradient on the diversity of the herb layer under Robinia pseudoacacia forests and Quercus acutissima forests. In Robinia pseudoacacia forests, the richness and other diversity indices of the herb layer are significantly higher at low elevations than at medium and high elevations, exhibiting a "low-elevation advantage" pattern. The richness and other diversity indices of the herb layer in Quercus acutissima forests are lower at medium and low elevations but significantly increase at high elevations. In different forest types, there is a significant correlation between herb layer richness and biomass, but in opposite directions: a negative correlation in Robinia pseudoacacia forests and a positive correlation in Quercus acutissima forests. The differences between Robinia pseudoacacia and Quercus acutissima forests may stem from the different nature of species interactions under these two types of forest stands: competitive interactions dominate in Robinia pseudoacacia forests, while complementary interactions are more prominent in Quercus acutissima forests. This study suggests that tree species composition plays a key role in regulating the relationship between biodiversity and ecosystem functions.