Shrub type dominates the vertical distribution of leaf C : N : P stoichiometry across an extensive altitudinal gradient

Abstract

Abstract. Understanding leaf stoichiometric patterns is crucial for improving predictions of plant responses to environmental changes. Leaf stoichiometry of terrestrial ecosystems has been widely investigated along latitudinal and longitudinal gradients. However, very little is known about the vertical distribution of leaf C : N : P and the relative effects of environmental parameters, especially for shrubs. Here, we analyzed the shrub leaf C, N and P patterns in 125 mountainous sites over an extensive altitudinal gradient (523–4685 m) on the Tibetan Plateau. Results showed that the shrub leaf C and C : N were 7.3–47.5 % higher than those of other regional and global flora, whereas the leaf N and N : P were 10.2–75.8 % lower. Leaf C increased with rising altitude and decreasing temperature, supporting the physiological acclimation mechanism that high leaf C (e.g., alpine or evergreen shrub) could balance the cell osmotic pressure and resist freezing. The largest leaf N and high leaf P occurred in valley region (altitude 1500 m), likely due to the large nutrient leaching from higher elevations, faster litter decomposition and nutrient resorption ability of deciduous broadleaf shrub. Leaf N : P ratio further indicated increasing N limitation at higher altitudes. Interestingly, drought severity was the only climatic factor positively correlated with leaf N and P, which was more appropriate for evaluating the impact of water status than precipitation. Among the shrub ecosystem and functional types (alpine, subalpine, montane, valley, evergreen, deciduous, broadleaf, and conifer), their leaf element contents and responses to environments were remarkably different. Shrub type was the largest contributor to the total variations in leaf stoichiometry, while climate indirectly affected the leaf C : N : P via its interactive effects on shrub type or soil. Collectively, the large heterogeneity in shrub type was the most important factor explaining the overall leaf C : N : P variations, despite the broad climate gradient on the plateau. Temperature and drought induced shifts in shrub type distribution will influence the nutrient accumulation in mountainous shrubs.

Altitudinal pattern of shrub biomass allocation in Southwest China

“…Shrubs are defined as medium-sized woody or small plants and are distinguished from trees by their short height (below 5 m) and multiple stems [ 37 ]. The patchy distribution and large differences in shrub size lead to large within-stand variations in biomass.…”

“…The geographic information (longitude, latitude, and altitude) of the sample sites was recorded using a global positioning system (GPS). MAP and MAT were obtained for each site from the China Meteorological Forcing Dataset with a spatial resolution of 0.1° × 0.1° in latitude and longitude and every 3 h from 1981 to 2008 [ 37 , 39 , 40 ]. Considering the varied and complicated topography and different drought conditions in Southwest China, we also analysed how the biomass changed with the drought index (reconnaissance drought index, RDI).…”

Plant type dominates fine‐root C:N:P stoichiometry across China: A meta‐analysis

“…the C:N:P ratio) has been widely used to infer nutrient limitation, biogeochemical cycle, and responses to environmental change (Elser, Fagan, Kerkhoff, Swenson, & Enquist, ; Sardans, Rivas‐Ubach, & Peñuelas, ). Previous studies have largely investigated C:N:P stoichiometry in leaves (Elser et al, ; Han, Fang, Reich, Ian Woodward, & Wang, ; Reich & Oleksyn, ; Sardans et al, ; Townsend, Cleveland, Asner, & Bustamante, ; Zhao, Reich et al, ). In contrast, much less is known about the C:N:P stoichiometry of roots, especially for fine roots (i.e.…”

Nitrogen and Phosphorus Concentration in Leaf Litter and Soil in Xishuangbanna Tropical Forests: Does Precipitation Limitation Matter?

“…Chave et al [60] found that annual rainfall did not explain any variation in annual litterfall from a meta-analysis of 81 South American tropical forest sites. Therefore, there were no precipitation or lagged precipitation effects on litterfall production in the stands without a seasonal shortage of water supply [17,61].…”

“…Other climatic factors, such as temperature, appear to be a partial driver of variations in senesced-leaf N and P [15], and thermal environment can also influence geographic patterns in leaf N and P [16]. In contrast, drought severity was also a key climatic factor correlated with leaf N and P, which was more appropriate for evaluating the impact of water status than precipitation [17].…”