Effects of different plantation years on grassland plant community in Maxian Mountain area of the Loess Plateau

Abstract

Plant communities in the Loess Plateau’s artificial afforestation forests play an important role in fragile ecosystem restoration. Therefore, the composition, coverage, biomass, diversity, and similarity of grassland plant communities in different years of artificial afforestation in cultivated land were investigated. The effects of years of artificial afforestation on grassland plant community succession in the Loess Plateau were also investigated. The results showed that as the number of years of artificial afforestation increased, grassland plant communities grew from scratch, constantly optimizing community components, improving community coverage, and increasing aboveground biomass. The community diversity index and similarity coefficient gradually approached those of a 10-year abandoned community that had recovered naturally. After 6 years of artificial afforestation, the dominant species of the grassland plant community changed from Agropyron cristatum to Kobresia myosuroides, and the main associated species changed from Compositae and Gramineae to Compositae, Gramineae, Rosaceae, and Leguminosae. The α-diversity index accelerated restoration, the richness index and diversity index increased, and the dominant index decreased. The evenness index had no significant difference from CK. The β-diversity index decreased as the number of years of afforestation increased. The similarity coefficient between CK and grassland plant communities in various lands changed from medium dissimilarity to medium similarity at 6 years of afforestation. According to the analysis of various indicators of the grassland plant community, the grassland plant community had a positive succession within 10 years of artificial afforestation on the cultivated land of the Loess Plateau, and the threshold of the years from slow to fast was 6 years.

Effects of different afforestation years on soil moisture and nutrient content in Maxian Mountain of the Loess Plateau

“…The tested soil site was semi-dry soft soil according to US Soil Taxonomy 31 . Rhododendron qinghaiense and Hippophae rhamnoides are the dominant species, with Lonicera hispida and red Arctous ruber companions 20 .…”

“…Spruce, Robinia pseudoacacia and apricots 19 are commonly used in the Loess Plateau of China, among which spruce is widely used in afforestation projects due to its cold-resistant and evergreen characteristics. Nevertheless, as the duration of artificial afforestation increases, pure spruce forests exhibit slow growth, short stature, and weakness 20 , resulting in low ecological restoration function and canopy closure 21 , biodiversity loss, soil fertility degradation, and reduced ecosystem stability 22 , 23 . Therefore, effectively harnessing the ecological service functions of the Loess Plateau Grain for Green Project, such as water storage, soil moisture retention, wind and sand prevention, and soil erosion control, emerges as a pressing issue in the management and protection of artificial forests.…”