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. To explore the differences in the carbon (C), nitrogen (N), and phosphorus (P) balance, the stoichiometry characteristics and stoichiometric homeostasis in elm and poplar plantations in the Horqin Sandy Land, we measured C, N, and P concentrations in leaves, branches, roots, litter, and soils and analyzed N and P resorption efficiencies in the two plantations. 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 leaf and root C:P and N:P during summer 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 N:P homeostasis than poplar. N and N:P homeostasis were greater in roots than in leaves and branches in the elm plantation, but they varied with soil N concentration and N:P in the poplar plantation. 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, showing an improved nutrient cycle in the plant–litter–soil system and increased soil C and N accumulation in the elm plantation. Therefore, compared with poplar, elm may be a more suitable afforestation tree species for the Horqin Sandy Land, in terms of promoting the accumulation of soil nutrients and enhancing nutrient cycling in the plant–litter–soil system.

Linkages Between Nutrient Resorption and Ecological Stoichiometry and Homeostasis Along a Chronosequence of Mongolian Pine Plantations

“…All plantations were established from non-vegetated sandy lands. Previous studies have shown that soil properties were relatively similar prior to afforestation, and that the C, N, and P concentrations were 3.15, 0.24, and 0.09 g kg −1 , respectively (Chen et al, 2004;Zhang et al, 2013;Wang et al, 2021b). The initial afforestation density was 2 × 3 m for all the stands.…”

“…We found that soil-available N:P ratios correlated with soil-total N:P ratios but not with needle N:P ratios (Supplementary Figure 3), which indicates that soil N:P ratios may be a better indicator than leaf N:P ratios of the variations in soil nutrient. In addition, other organs (such as branch, root; Wang et al, 2021b) and needle age (Yuan et al, 2017) have great influences on nutrient uptake, transport, consumption, and storage. Further research is needed to consider nutrient allocation and translocation among different organs and age-class needles.…”

Analysis of nutrient resorption efficiency and homeostasis of four tree species in Kanas natural forest, Xinjiang, China

“…(2) Plant homeostasis reflects the ability of organisms to maintain their nutrient composition relatively constant irrespective of changing environmental nutrient status (Persson et al, 2010;Yu et al, 2011), which is calculated by the following formula (Wang et al, 2021):…”

Reducing Nutrient Loss Caused by Thinning: Effects of Four Composts of Forest Thinning Shreds on Soil Nutrients and Tree Growth in Semimature Pinus tabuliformis Carr., Beijing, China

“…This is because there is less litter in the Pinus tabuliformis forest and the forest surface cover is thin, so the soil surface temperature is high, the water content is low [38], and the microliving activities of the lower soil are weakened. In addition, C and N are apparent [39], the adsorption of P by soil is strong, the mineralization of deep soil is blocked, and the downward migration of various components in the soil is reduced.…”