The C:N:P Stoichiometry of Planted and Natural Larix principis-rupprechtii Stands along Altitudinal Gradients on the Loess Plateau, China

Abstract

Carbon:nitrogen:phosphorus (C:N:P) stoichiometry plays a critical role in nutrient cycling, biodiversity, and ecosystem functionality. However, our understanding of the responses of C:N:P stoichiometry to elevation and forest management remains elusive. Here we sampled 18 Larix principis-rupprechtii sites along altitudinal gradients (1700-2300 m) on Guandishan Mountain in the Loess Plateau, China. We determined the leaf, litter, and soil C N P contents and C:N:P stoichiometric ratios, as well as nutrient resorption efficiency (NuRE), and diameter at breast height (DBH) increments in both planted and natural stands, and then tested the impacts of elevation and stand origin on these parameters’ management. We found different C:N:P stoichiometry between natural and planted forests. The results revealed that: soil C, N, and N:P ratios, litter C:P and N:P ratios, leaf C:N and N:P ratios increased significantly; however, soil C:N ratios, litter P, leaf N and P, nitrogen resorption efficiency (NRE), and DBH increments decreased significantly with elevation in the planted forests. Soil C,N and N:P ratios, litter C, as well as C:N and C:P ratios increased significantly with elevation in natural forests. The soil N, P and N:P ratios, litter C:P and N:P ratios, leaf C, C:P and N:P ratios, nitrogen resorption efficiency (NRE), phosphorus resorption efficiency (PRE), and DBH increments were, on average, higher in the planted, rather than natural forests. Our results indicated that there was an enhancing P-limitation in both the planted and natural forests, and the plantations were more restricted by P. Moreover, compared to natural forests, plantations converged toward a higher conservative N- and P-use strategy by enhancing resorption efficiencies of internal nutrient cycling and a higher annual growth rate.

C:N:P Stoichiometry of Plant, Litter and Soil along an Elevational Gradient in Subtropical Forests of China

“…Among the observed variables, elevation was an essential environmental factor that correlated negatively to the stoichiometric ratio of plant and litter, and air temperature had an indirect positive effect on the stoichiometric ratio of plants (Table 2). This result corresponds with Bo et al [51], who observed that plant growth requires more nutrients (mainly N and P) to adapt to changes in the surrounding environment under cold climates, resulting in a smaller increase in C than N and P contents and a smaller increase in N than P contents. Soil pH was the main environmental factor that correlated negatively to the soil stoichiometry ratio (Table 2), which has been proved by previous studies on microbial composition affected by pH in an arable soil [52][53][54].…”

Response of leaf stoichiometry of Potentilla anserina to elevation in China's Qilian Mountains

“…This may be because photosynthesis was inhibited when the temperature dropped with an increase in elevation, which in turn weakened their carbon assimilation ability (Öquist, 1983 ). However, some studies (e.g., Zhao et al, 2018 ; Bo et al, 2020 ; Waigwa et al, 2020 ) reported that [C] leaf tended to be greater at higher elevations to balance cell osmotic pressure and improve the frost resistance of plants (Zhao et al, 2018 ). These conflicting results suggest that the response of [C] leaf to elevation still requires further studies based on species and at the regional level.…”

“…Relationships between leaf stoichiometry and environmental factors, including soil nutrients and geographical and climatic factors, were widely explored at various scales including regional and global scales (e.g., McGroddy et al, 2004 ; Reich and Oleksyn, 2004 ; Sardans et al, 2011 ; Du et al, 2017 ; Tian et al, 2018 ; Qin et al, 2021 ). Elevation is a crucial factor and can affect plant leaf stoichiometry by altering the combination of heat and water, soil properties, and vegetation community composition (Bo et al, 2020 ; Liu et al, 2021 ). However, there is little consensus on leaf stoichiometric characteristics as they change along an elevation gradient.…”

“…However, there is little consensus on leaf stoichiometric characteristics as they change along an elevation gradient. Some studies observed that leaf C concentration [(C) leaf ] increased but leaf N [(N) leaf ] and leaf P concentration [(P) leaf ] decreased with an increase in elevation (e.g., Zhao et al, 2014 , 2018 ; Bo et al, 2020 ), while other studies reported an opposite trend (e.g., Macek et al, 2009 ; Li et al, 2018 ). Therefore, the response of plant leaf ecological stoichiometry to elevation should be investigated at regional and species-specific levels.…”

Influence of Mycorrhiza on C:N:P Stoichiometry in Senesced Leaves

“…Yan et al [ 30 ] have also concluded that there is a strong correlation between leaf stoichiometry and water use efficiency in plants. Meanwhile, leaf C:N:P stoichiometry is significantly affected by many factors, including climate [ 31 , 32 ], external nutrient availability [ 33 , 34 ], arbuscular mycorrhiza [ 16 , 17 ] and environmental conditions [ 35 , 36 ]. However, the relationship between senesced leaves’ stoichiometry and plant mycorrhizal association remains unknown.…”