Warming and Nitrogen Addition Alter Photosynthetic Pigments, Sugars and Nutrients in a Temperate Meadow Ecosystem

Abstract

Global warming and nitrogen (N) deposition have an important influence on terrestrial ecosystems; however, the influence of warming and N deposition on plant photosynthetic products and nutrient cycling in plants is not well understood. We examined the effects of 3 years of warming and N addition on the plant photosynthetic products, foliar chemistry and stoichiometric ratios of two dominant species, i.e., Leymus chinensis and Phragmites communis, in a temperate meadow in northeastern China. Warming significantly increased the chlorophyll content and soluble sugars in L. chinensis but had no impact on the carotenoid and fructose contents. N addition caused a significant increase in the carotenoid and fructose contents. Warming and N addition had little impact on the photosynthetic products of P. communis. Warming caused significant decreases in the N and phosphorus (P) concentrations and significantly increased the carbon (C):P and N:P ratios of L. chinensis, but not the C concentration or the C:N ratio. N addition significantly increased the N concentration, C:P and N:P ratios, but significantly reduced the C:N ratio of L. chinensis. Warming significantly increased P. communis C and P concentrations, and the C:N and C:P ratios, whereas N addition increased the C, N and P concentrations but had no impact on the stoichiometric variables. This study suggests that both warming and N addition have direct impacts on plant photosynthates and elemental stoichiometry, which may play a vital role in plant-mediated biogeochemical cycling in temperate meadow ecosystems.

Warming impacts on carbon, nitrogen and phosphorus distribution in soil water-stable aggregates

“…Also, warming had no significant effect on C:N and C:P ratios in bulk soil (Figure 3). Our result was consistent with the findings of previous studies conducted in other grassland ecosystems (Wang et al 2014, Yu et al 2014, Zhang et al 2015, 2016 Aggregates size class (mm) ratios to warming in the alpine meadow ecosystem were of importance for ecological stability in this region under climate warming scenario. In the previous studies (Wang et al 2014, Yu et al 2014, changes in biotic (e.g., vegetation biomass, microbial activity) and abiotic factors (e.g., soil moisture, elevational gradient) were considered to be responsible for the insignificant changes of soil nutrients.…”

“…However, no consistent results have been presented so far. Some studies showed that warming did not affect soil organic carbon (OC), total N (TN), and total P (TP) contents (Wang et al 2014, Yu et al 2014, Zhang et al 2015, 2016, whereas other studies found that warming significantly decreased soil OC, TN and TP contents (Li et al 2011, Rui et al 2012, Alatalo et al 2017). Both biotic (e.g., vegetation biomass, microbial activity) and abiotic factors (e.g., soil moisture, elevational gradient) were considered to contribute to the contradictory findings (Wang et al 2014, Yu et al 2014.…”

Effects of Warming and N Deposition on the Physiological Performances of Leymus secalinus in Alpine Meadow of Qinghai-Tibetan Plateau

“…The possible reason might be that N deposition can further increase soil N availability and promote plant N uptake, leading to enhanced photosynthetic pigment synthesis (Zhang et al, 2013). Additionally, increase of chlorophyll suggested that N deposition could also promote photosynthesis (Zhang et al, 2016). The combined effects of warming and N deposition also significantly promoted the synthesis of photosynthetic pigments, while the impacts were not as stronger as warming alone.…”

The additive effect of biochar amendment and simulated nitrogen deposition stimulates the plant height, photosynthesis and accumulation of NPK in pecan (Carya illinoinensis) seedlings

“…N supplementation directly affects the photosynthetic pigment content in leaves as well as the activity of ribulose 1,5-bisphosphate carboxylase, the enzyme in leaves essential for atmospheric CO 2 fixation ( Makino et al 2000 ). Furthermore, soil acidification may lead to the adsorption of alkaline cations, disruption of nutrient balance and inhibition of photosynthesis ( Bergkvist and Folkeson 1992 ; Zhang et al 2016 ). The present work found that with a low level of N application in the absence of BC amendment, the photosynthetic pigments Car, Chla and Chlb increased, whereas a high level of N application suppressed the accumulation of the pigments.…”