Plant-litter-soil ecological stoichiometry and stoichiometric homeostasis of tree tissues under three desertified grassland restoration modes in northern China

Abstract

Afforestation is the primary strategy to address ecological degradation in northern China’s Horqin sandy region. This study utilized ecological stoichiometry as field study indicators and laboratory analysis to assess the afforestation strategies of three indigenous tree species to restore sandy grassland. The three restoration strategies were as follows: (1) grasslands were enclosed by a Populus × beijingensis shelterbelt (FG); (2) Pinus sylvestris var. mongolica was used for the afforestation of small, well-distributed grassland patches (MG); and (3) Ulmus pumila was used for the afforestation of small, well-distributed patches (UG). The results revealed FG, MG, and UG had significantly different C:N:P ratios as well as significant variations in the amounts of C, N, and P in the plants, litters, and soils. After more than 20 years of recovery, it was discovered that all three treatments had a substantial effect on the C:N, N:P, and C:P ratios of the soil in comparison to the CK. The N:P results in various tissues demonstrated that N-limited was the case with the FG, MG, and UG restorations. There was N and P homeostasis in the trees, particularly Populus × beijingensis whereas the species of afforestation and plant tissues had a major influence on the degree of homeostasis. FG was better suitable for the arid climate in this area, according to the ecological stoichiometry results of C, N, and P content and stoichiometric homeostasis. The research results can provide scientific basis for the ecological restoration and vegetation reconstruction of fragile ecological areas in Inner Mongolia, China.