Groundwater Depth Affects Phosphorus But Not Carbon and Nitrogen Concentrations of a Desert Phreatophyte in Northwest China

Abstract

Ecological stoichiometry is an important aspect in the analysis of the changes in ecological system composition, structure, and function and understanding of plant adaptation in habitats. Leaf carbon (C), nitrogen (N), and phosphorus (P) concentrations in desert phreatophytes can be affected by different depths of groundwater through its effect on the adsorption and utilization of nutrient and plant biomass. We examined the biomass, soil organic C, available (mineral) N, and available P, and leaf C, N, and P concentrations of Alhagi sparsifolia grown at varying groundwater depths of 2.5, 4.5, and 11.0 m in 2015 and 2016 growing seasons in a desert-oasis ecotone in northwest China. The biomass of A. sparsifolia and the C, N, and P concentrations in soil and A. sparsifolia showed different responses to various groundwater depths. The leaf P concentration of A. sparsifolia was lower at 4.5 m than at 2.5 and 11.0 m likely because of a biomass dilution effect. By contrast, leaf C and N concentrations were generally unaffected by groundwater depth, thereby confirming that C and N accumulations in A. sparsifolia were predominantly determined by C fixation through the photosynthesis and biological fixation of atmospheric N2, respectively. Soil C, N, and P concentrations at 4.5 m were significantly lower than those at 11.0 m. Leaf P concentration was significantly and positively correlated with soil N concentration at all of the groundwater depths. The C:N and C:P mass ratios of A. sparsifolia at 4.5 m were higher than those at the other groundwater depths, suggesting a defensive life history strategy. Conversely, A. sparsifolia likely adopted a competitive strategy at 2.5 and 11.0 m as indicated by the low C:N and C:P mass ratios. To our knowledge, this study is the first to elucidate the variation in the C, N, and P stoichiometry of a desert phreatophyte at different groundwater depths in an arid ecosystem.

Convergent Variations in the Leaf Traits of Desert Plants

“…Therefore, the SMC showed a positive significant relationship with the SOC and STN, ensuing in variations in leaf P contents due to interactive relationships among SOC, STN and STP. The results of the present study corroborated the findings of a recent study [ 33 ] that the source of plant nutrients was not merely soil but also groundwater/SMC. Furthermore, soil pH and SMC also affect concentration and storage of SOC, STN, and STP [ 81 , 87 ].…”

“…The pattern of leaf traits concentration for all 37 species was investigated ( Table 2 ). In the present study, it is noted that the mean leaf C concentration of all 37 plant species ( Table 2 ) was higher than that in leaves of plant species studied across the China [ 32 ], plants of the Taklamakan Desert [ 33 ] and especially higher than herbs of the Yucatan Mexico [ 34 ]. Results of the current study further investigated that the mean leaf N concentration ( Table 2 ) significantly higher than the global plants [ 35 ], China’s terrestrial ecosystems [ 32 ], herbs studied across China [ 36 ] and markedly lower than the KMUNR desert plants [ 37 ].…”

Trade-off relationship of leaf functional traits of desert halophyte Lycium ruthenicum in the lower reaches of Heihe River, Northwest China: response to soil moisture and salinity

“…Due to this, SWC has a great impact on the levels of leaf P and N:P, and HCO 3 affects the production of leaf dry matter content. The result was supported by other observations [53].The changing C:P pattern along environmental gradients suggested that L. ruthenicum had a exible life strategy under different environments. In the deeper soil layer, HCO 3 -, followed by SO 4…”

Trade-off strategy of leaf functional traits of desert halophyte Lycium ruthenicum in the lower reaches of Heihe River, Northwest China: response to soil moisture and salinity

“…Between them, SWC has larger contributions to leaf P content, N:P ratios and C:P ratios while HCO 3 has the greatest impact on LDMC, these can be inferred from previous research: In desert ecosystems, low soil moisture coupled with high soil alkalinity acts to decrease both soil N and P availability [52], Due to this, here SWC has a great impact on the levels of leaf P and N:P, and HCO 3 affects the production of dry matter content. Results which are partially supported by evidence from other observations [53]. Changing C:P pattern along environmental gradients suggests that L.…”