A new afforestation method can accelerate nutrient return from litterfall- a 17-year observation on the Eastern Tibetan Plateau

Restoring degraded ecosystems through mixed-species plantations is a vital strategy for addressing global land degradation, as it enhances ecosystem functions more effectively than monoculture plantations. However, the ecological functions of mixed-species plantations, particularly those with indigenous tree species, have been insufficiently studied. This study aimed to assess carbon and nutrient return from litterfall production in a high indigenous-species diversity plantation (HISD plantation) utilizing a novel strip-cutting shrubs method, in comparison with a secondary forest with natural regeneration over a 17-year period. The results clearly showed that the annual litterfall production was 47% higher, resulting in higher C (50%), P (31%), and N (8%) return from litterfall in the HISD plantation over the secondary forest. Specifically, leaves (52%), twigs (36%) and reproductive (28%) litter production were also higher in the HISD plantation than in the secondary forest. The enhancement in litterfall production was influenced by factors including tree community parameters like basal area, soil fertility (N, P and available P), and climatic variables such as annual mean temperature and precipitation. The superior basal area of canopy trees and improved soil fertility in the HISD plantation were key contributors to the increased litterfall production relative to the secondary forest. These findings suggest that strip-cutting shrubs restoration is an effective technique to accelerate litterfall production and enhance carbon and nutrient return from litter, thereby aiding in the recovery of soil fertility in this region.