Comparison of C:N:P stoichiometry in the plant–litter–soil system
between poplar and elm plantations in the Horqin Sandy Land, China
Abstract
Afforestation is among the most effective means of preventing and
controlling desertification. Silver poplar (Populus alba) is commonly
planted tree species for afforestation of the Horqin Sandy Land of
China. However, this species has exhibited some drawbacks such as top
shoot dieback, premature senescence and mortality, and soil and
ecosystems degradation. In contrast, Siberian elm (Ulmus pumila) rarely
experiences these problems in the same regions. Ecological stoichiometry
plays a vital role in exploring ecological processes and nutrient cycle
relationships in plant–litter–soil systems. We measured C, N, and P
concentrations in leaves, branches, roots, litter, and soils and
analyzed N and P resorption efficiencies, and stoichiometric homeostasis
in elm and poplar plantations in the Horqin Sandy Land. The results
showed that soil C and N concentrations, C:P, and N:P were greater in
the elm plantation than in the poplar plantation. The plant N
concentrations, C:P, and N:P and litter N and P concentrations were
greater, whereas N and P resorption efficiencies were lower, in the elm
plantation than in the poplar plantation. Generally, elm exhibited
greater homeostasis than poplar. These findings indicate that poplar
exhibited more developed internal nutrient conservation and allocation
strategies but poor nutrient accumulation in soil, which may contribute
to degradation of poplar plantation. In contrast, elm tended to return
more nutrients to the soil. Therefore, compared with poplar, elm may be
a more suitable afforestation tree species for the Horqin Sandy Land,
where it may promote the accumulation of soil nutrients and enhance
ecosystem stability.