C:N:P stoichiometry and nutrient resorption in mixed-species and monoculture forest plantations on the Loess Plateau, China

Abstract

Abstract Effects of mixed-species on leaf and soil stoichiometry of nitrogen (N), carbon (C), and phosphorous (P) and foliar nutrient resorption efficiency are unclear. We analyzed the effects of stand structure, understory plant species diversity, and soil properties associated with mixed plantations of Robinia pseudoacacia + Amygdalus davidiana (RPAD) and R. pseudoacacia + Armeniaca sibirica (RPAS) and monocultures of R. pseudoacacia (RP); A. davidiana (AD), and A. sibirica (AS) on tree leaf and soil C:N:P stoichiometry, resorption efficiency of N (NRE) and P (PRE) on the Loess Plateau. The soil total C content in RPAD and soil total N content in RPAS were greater than for monocultures RP, AD, and AS. The highest soil C:N and C:P ratios were recorded from RPAD and the lowest were recorded from RPAS; leaf P content was greater in RPAD than RP and AD, while leaf C:N and C:P ratios were lower. NRE and PRE was lower in the mixed plantations than in RP, and PRE was lower in RPAS than in RPAD. Stoichiometry of leaf and soil C:N:P in the mixed and monoculture plantations was affected by stand and canopy densities, average tree height (AH), soil available P, and electrical conductivity. NuRE was positively correlated with leaf N content and N:P ratios, and AH, and negatively correlated with leaf C:N ratios and soil total P content. The planting of RPAD mixed plantation to increase productivity and to improve biogeochemical cycling and contribute to the restoration of ecosystem function.