Impact of elevated precipitation, nitrogen deposition and warming on soil respiration in a temperate desert

Abstract

Abstract. Soil respiration (Rs) is the most important source of carbon dioxide emissions from soil to atmosphere. However, it is unclear what the interactive response of Rs would be to environmental changes such as elevated precipitation, nitrogen (N) deposition and warming, especially in unique temperate desert ecosystems. To investigate this an in situ field experiment was conducted in the Gurbantunggut Desert, northwest China, from September 2014 to October 2016. The results showed that precipitation and N deposition significantly increased Rs, but warming decreased Rs, except in extreme precipitation events, which was mainly through its impact on the variation of soil moisture at 5 cm depth. In addition, the interactive response of Rs to combinations of the factors was much less than that of any single-factor, and the main response was a positive effect, except for the response from the interaction of increased precipitation and high N deposition (60 kg N ha−1 yr−1). Although Rs was found to show a unimodal change pattern with the variation of soil moisture, soil temperature and soil NH4+-N content, and it was significantly positively correlated to soil dissolved organic carbon (DOC) and pH, a structural equation model found that soil temperature was the most important controlling factor. Those results indicated that Rs was mainly interactively controlled by the soil multi-environmental factors and soil nutrients, and was very sensitive to elevated precipitation, N deposition and warming. However, the interactions of multiple factors largely reduced between-year variation of Rs more than any single-factor, suggesting that the carbon cycle in temperate deserts could be profoundly influenced by positive carbon–climate feedback.

Involvement of soluble proteins in growth and metabolic adjustments of drought‐stressed Calligonum mongolicum seedlings under nitrogen addition

“…A transparent plastic film was placed over the pots when it rained. Due to the rapid development of agriculture and industry, there is prominent N deposition (3.5 gNÁm −2 Áyear −1 ) in northwestern China (Yue et al 2019), and this rate is expected to double by 2050 (Galloway et al 2008). Extreme N deposition events have occurred in the North China Plain, where the rate is 9.0 gNÁm −2 Áyear −1 (Liu et al, 2013).…”

“…Atmospheric nitrogen (N) derived from anthropogenic activities (e.g. fossil fuel consumption and chemical fertilizer application) has been increasing in recent decades, including in northwestern China (Liu et al 2013;Yue et al 2019). Moreover, drought events have become more frequent (IPCC 2013).…”

Are annual nitrous oxide fluxes sensitive to warming and increasing precipitation in the Gurbantunggut Desert?

“…This soil is a desert solonetz with a sand content of almost 80% (Huang, Cao, et al, 2015). Mean available soil N content is less than 6 mg kg −1 (Yue et al, 2018). The cover of herbaceous plants, including ephemerals, annuals and small perennials, reaches up to 40% in spring (Liu et al, 2016).…”

“…, moisture, temperature and pH were determined as described byYue et al (2018). Below-ground biomass (UGB) of the ephemeral plants was measured by digging up its roots in a 1 m 2 area of the plot.…”

Future N deposition and precipitation changes will be beneficial for the growth of Haloxylon ammodendron in Gurbantunggut Desert, northwest China

“…The total N content and ratio of C to N are 0.08 g kg −1 ± 0.003 g kg −1 and 21.39 ± 1.84, respectively 14 . Haloxylon persicum and H. ammodendron dominate floral species, with approximately 30% coverage 44 , with herbs comprising some other dominant species.…”