Increasing aridity, temperature and soil pH induce soil C-N-P imbalance in grasslands

Abstract

Due to the different degrees of controls exerted by biological and geochemical processes, climate changes are suggested to uncouple biogeochemical C, N and P cycles, influencing biomass accumulation, decomposition and storage in terrestrial ecosystems. However, the possible extent of such disruption in grassland ecosystems remains unclear, especially in China’s steppes which have undergone rapid climate changes with increasing drought and warming predicted moving forward in these dryland ecosystems. Here, we assess how soil C-N-P stoichiometry is affected by climatic change along a 3500-km temperate climate transect in Inner Mongolia, China. Our results reveal that the soil from more arid and warmer sites are associated with lower soil organic C, total N and P. The ratios of both soil C:P and N:P decrease, but soil C:N increases with increasing aridity and temperature, indicating the predicted decreases in precipitation and warming for most of the temperate grassland region could lead to a soil C-N-P decoupling that may reduce plant growth and production in arid ecosystems. Soil pH, mainly reflecting long-term climate change in our sites, also contributes to the changing soil C-N-P stoichiometry, indicating the collective influences of climate and soil type on the shape of soil C-N-P balance.

Does Caragana korshinskii plantation increase soil carbon continuously in a water‐limited landscape on the Loess Plateau, China?

“…However, it has been suggested that the carbon and nitrogen cycles could become uncoupled under climate change because of the different degrees of control exerted on the supply of these elements by biological and geochemical processes (Delgado‐Baquerizo et al, ; Wardle, ). Increase in aridity with climate change has disturbed nutrients cycles in global dryland soils (Wang et al, ) and negatively affected the concentration of SOC and STN (Delgado‐Baquerizo et al, ; Jiao, Shi, Han, & Yuan, ). C. korshinskii has well‐developed root systems and fast growth or expansion (Maestre et al, ), at the expense of great water consumption stored throughout the soil profile (Jia et al, ; Wang et al, ).…”

Water and heat availability are drivers of the aboveground plant carbon accumulation rate in alpine grasslands on the Tibetan Plateau

“…An interesting question arises: why was the change in the community CAR relatively minor for the MCAR pattern compared with the LCAR pattern ( Figure 1e)? First, despite the increase in AMP that stimulated plant growth (Figure 4b) and carbon uptake (Niu et al, 2008), the significantly negative linkage between the AMT and CAR to support plant carbon accumulation (Jiao, Shi, Han, & Yuan, 2016;Melillo et al, 2002), with MMPs of 17.80 and 22.87 mm (Supporting Information Figure 1a,b), respectively. First, despite the increase in AMP that stimulated plant growth (Figure 4b) and carbon uptake (Niu et al, 2008), the significantly negative linkage between the AMT and CAR to support plant carbon accumulation (Jiao, Shi, Han, & Yuan, 2016;Melillo et al, 2002), with MMPs of 17.80 and 22.87 mm (Supporting Information Figure 1a,b), respectively.…”

“…Here, we F I G U R E 5 Relationships among annual mean precipitation (AMP), annual mean temperature (AMT) and carbon accumulation rate (CAR) for the low CAR (LCAR) (a), medium-CAR (MCAR) (b) and high-CAR (HCAR) patterns (c); and relationships between AMP and AMT for the low CAR (LCAR) (d), medium-CAR (MCAR) (e) and high-CAR (HCAR) patterns (f) [Colour figure can be viewed at wileyonlinelibrary.com] propose two explanations. The low MMP in April, together with the non-significant linkages between MMT and MMP in May (Supporting Information Figure 2b) and June (Supporting Information Figure 2c), demonstrated that the environmental conditions were still not ideal for plant growth (Jiao et al, 2016;Lambers, Raven, Shaver, & Smith, 2008). The low MMP in April, together with the non-significant linkages between MMT and MMP in May (Supporting Information Figure 2b) and June (Supporting Information Figure 2c), demonstrated that the environmental conditions were still not ideal for plant growth (Jiao et al, 2016;Lambers, Raven, Shaver, & Smith, 2008).…”

Shrub encroachment increases soil carbon and nitrogen stocks in temperate grasslands in China

“…In our study areas, the MAP ranges from 200 to 350 mm, and water becomes a constraining factor regulating C and N accumulation (He, Wang, Zhang, & Chen, ; Kulmatiski & Beard, ). In this situation, lower temperatures may result in reduced water stress, less severe depletions of C and N inputs, and decreased biological processes (Jiao, Shi, Han, & Yuan, ). In addition, our results emphasize the regulatory effect of soil factors on C and N accumulation, as we found that changes in SOCD and STND were significantly negatively correlated with pH.…”