Non-linear responses of net ecosystem productivity to gradient warming in a paddy field in Northeast China

Abstract

Global warming has a known impact on ecosystems but there is a lack of understanding about its impact on ecosystem processes. Net ecosystem productivity (NEP) and its components play a key part in the global carbon cycle. Analysing the impact of global warming on NEP will improve our understanding of how warming affects ecosystems. In our study, conducted in 2018, five warming treatments were manipulated (0 W, 500 W, 1000 W, 1500 W, and 3000 W) using three repetitions of far infrared open warming over a paddy field in Northeast China. NEP and its two related components, gross primary productivity (GPP) and ecosystem respiration (ER), were measured using the static chamber-infrared gas analyser method to explore the effects of different warming magnitudes on NEP. Results showed that measurement dates, warming treatments, and their interactions significantly affected NEP, ER, and GPP. Warming significantly increased NEP and its components but they showed a non-linear response to different warming magnitudes. The maximum increases in NEP and its components occurred at 1500 W warming. NEP is closely related to its components and the non-linear response of NEP may have primarily resulted from that of GPP. Gradient warming non-linearly increased GPP in the paddy field studied in Northeast China, resulting in the non-linear response of NEP. This study provides a basis for predicting the responses of carbon cycles in future climate events.

Estimating the Net Ecosystem Exchange at Global FLUXNET Sites Using a Random Forest Model

“…Accurately estimating NEE based on data-driven machinelearning methods is more dependent on a lack of information than the algorithm [3]. Missing key information in the predictors likely hinders the understanding of the spatiotemporal variability of NEE, which includes missing information in the input variables for the soil carbon stock, plant production, and heterotrophic respiration components of NEE [19,21,22], insufficient characterization of water availability, and topographic effects [3,14,20]. This is a challenge that every upscaling approach for carbon fluxes needs to tackle [4].…”