Long-term effects of vegetation restoration and forest management on carbon pools and nutrient storages in northeastern Loess Plateau, China.

ABSTRACT

It is crucial for understanding the variations of carbon and nutrient pools within the ecosystems during long-term vegetation restoration to accurately assess the effects of different ecological restoration patterns. However, the long-term spatio-temporal variations of carbon and nutrient pools under different vegetation types remain unclear. The sites for long-term natural and planted forests (i.e., Natural secondary forest, Pinus tabulaeformis planted forest, Platycladus orientalis planted forest, and Robinia pseudoacacia planted forest) on the northeastern Loess Plateau, China were selected, to measure and analyze the differences and interannual variations of vegetation attributes at four synusiae and soil properties at 0-100 cm over the period of 12 years (2006-2017). The principal component analysis (PCA) and Mantel test were also conducted to explore the relationships among vegetation attributes, soil properties, and carbon and nutrient pools. The results showed that compared with the planted forests, the natural secondary forest had lower arborous biomass (84.21 ± 1.53 t hm-2) and higher understory biomass and plant heights. Compared to planted forests, the secondary forest had higher soil carbon and nitrogen contents (13.74 ± 3.50 g kg-1 and 1.16 ± 0.34 g kg-1). The soil carbon pool in the secondary forest was 22.0% higher than planted forests, while the vegetation carbon pool in the P. tabulaeformis was 75.5% higher than other forests. Principal component analysis (PCA) and Mantel test revealed that vegetation attributes and soil properties had significant correlations with carbon and nutrient pools, especially at the arborous synusia (p < 0.01). The findings indicated that in the ecologically fragile Loess Plateau region, the selection of appropriate vegetation restoration types should be guided by varying ecological restoration goals and benefits, aiming to expected ecological outcomes. This insight offers a strategic implication for forest management that is tailored to improve carbon and nutrient pools in areas with similar environmental conditions.