Mechanisms regulating the productivity and stability of artificial grasslands in China: Issues, progress, and prospects

Abstract

China has 400 million hectares of grasslands, occupying 41.7% of the country’s total land area. Due to the overexploitation of grassland’s production functions and the neglect of its ecological functions, intensive livestock grazing in recent decades has resulted in widespread grassland degradation, reduction in ecosystem services, and imbalance between forage production and livestock demands in China. Compared to natural grasslands, artificial grasslands can increase forage yield up to 10–20 times. The development of high-quality artificial grasslands could fundamentally ease the severe shortage of forage supply, break the bottleneck in meat and milk production, curb grassland degradation caused by overgrazing, and thereby restore grassland ecological functions. Therefore, understanding the mechanisms that regulate the productivity and stability of artificial grasslands is a major national strategic need in order to transform the practices of sustainable livestock production based on the scientific and technological advancements, and to promote national ecological security, food security, and the development of ecological civilization. In this study, we examined theoretical basis underlying the regulations of artificial grassland productivity and stability, including theories of ecological stoichiometry, niche differentiation, compensation, mutualism, grazing optimization, and intermediate disturbance. Then, we reviewed current research status and the latest progress that has made in this field. Finally, we proposed fundamental research questions that need to be fully addressed in future studies, regarding the effects of stoichiometry of key nutrient elements, coupled water and nutrient availability, mutualism between forage species and soil microbes, and complementarity of functional traits and multiple forage species on plant carbon assimilation, growth, reproduction, forage quality, biomass allocation, primary productivity, and ecosystem stability. We also highlighted several key biological and ecological mechanisms regulating the productivity and stability of artificial grasslands.