Climate Change Can Accelerate Depletion of Montane Grassland C Stocks

Abstract

Climate warming and management will likely affect carbon (C) fluxes of montane grassland ecosystems. In this study, we assessed the effect of simultaneous warming (+2°C) and decreased precipitation (−25%) on carbon exchange of montane grasslands in S-Germany by translocating large intact plant-soil cores from a high altitude to a low altitude site. Cores received two common grassland management regimes: intensive (4-5 cuts and slurry application) and extensive (1-2 cuts and slurry application). Diurnal patterns of net ecosystem exchange (NEE) and total ecosystem respiration (Reco) were measured over 1.5 years in 2-3 weeks intervals during the snow free period. Additional data on environmental controls, that is, photosynthetic active radiation, grass height and soil moisture and temperature, were used to develop empirical models to estimate daily and annual fluxes of gross primary production (GPP) and Reco. Considering the 2 years period (2014 and 2015), we found that, under warmer and slightly drier conditions, both GPP and Reco significantly (p < 0.01) increased (up to 20%) but with a higher temperature sensitivity of Reco, particularly in intensive managed grassland. The higher temperature sensitivity of Reco reduced the NEE by 0.7 t C ha −1 yr −1 for both extensive and intensive management, respectively. Considering additional carbon inputs via slurry and exports via harvest (i.e., annual net ecosystem carbon budget), our results showed that managed grasslands are already a source of C under current climate conditions (1.7-1.8 t ha −1 yr −1 ) which significantly (p < 0.05) increased under climate warming (2.3-2.9 t ha −1 yr −1 ).

Effect of Subirrigation and Silicon Antitranspirant Application on Biomass Yield and Carbon Dioxide Balance of a Three-Cut Meadow

“…Furthermore, other agronomic practices like meadow management, fertilization, and cutting frequency may also impact root biomass. For example, Wang et al [48] and De Vries et al [49] indicated a higher belowground carbon allocation and higher root biomass in extensively managed grasslands, when compared to intensively managed meadows. Also, Poyda et al [50] pointed out that highly fertilized grasslands may lose carbon sequestration capacity due to low underground C allocation.…”

“…During a dry year, the grassland was a net source of CO 2 to the atmosphere, whereas during a normal year, CO 2 uptake prevailed. Furthermore, it has been shown that climate change, warmer conditions, and intensive grassland management can negatively affect grassland carbon balances and result in a less-negative annual NEE [48]. However, Zhang et al [63] found that water availability is more important than temperature for shaping carbon fluxes from alpine meadows.…”

The SOC of steppe grasslands is more sensitive to grazing than desert-steppe grasslands and is regulated by precipitation outside the growing season in the Mongolian Plateau

“…In addition to grassland management practices, environmental factors can exert a substantial in uence on the carbon balance of grasslands (Wang et al 2021). Temperature exerts a substantial in uence on the inputs and losses of soil carbon, as the correlated physiological, chemical, and biochemical processes are all contingent upon temperature.…”

“….2. Response of SOC to climate factorsAs many studies reported, the climate plays a crucial role in regulating the total amount of carbon stored in the soil as many studies reported(Ou et al 2017;Wang et al 2021). Climate change has the potential to directly impact the amount of Soil Organic Carbon (SOC) in the soil.…”