Abstract
Grassland managements can affect carbon (C) and nitrogen (N) storage in grassland ecosystems with consequent feedbacks to climate change. We investigated the impacts of compound fertilization and clipping on grass biomass, plant and soil (0–20 cm depth) C, N storage, plant and soil C: N ratios, soil microbial activity and diversity, and C, N sequestration rates in grassland in situ in the National Dalaoling Forest Park of China beginning July, 2011. In July, 2012, the fertilization increased total biomass by 30.1%, plant C by 34.5%, plant N by 79.8%, soil C by 18.8% and soil N by 23.8% compared with the control, respectively. Whereas the clipping decreased total biomass, plant C and N, soil C and N by 24.9%, 30.3%, 39.3%, 18.5%, and 19.4%, respectively, when compared to the control. The plant C: N ratio was lower for the fertilization than for the control and the clipping treatments. The soil microbial activity and diversity indices were higher for the fertilization than for the control. The clipping generally exhibited a lower level of soil microbial activity and diversity compared to the control. The principal component analysis indicated that the soil microbial communities of the control, fertilization and clipping treatments formed three distinct groups. The plant C and N sequestration rates of the fertilization were significantly higher than the clipping treatment. Our results suggest that fertilization is an efficient management practice in improving the C and N storage of the grassland ecosystem via increasing the grass biomass and soil microbial activity and diversity.
Highlights
The grasslands in China cover an area of 3.92 million km2 and provide 9% to 16% of the total C in the world grasslands [1,2,3]
Previous studies investigated the effect of fertilizer on the grassland C and N storage and indicated that the accumulation of soil C and N were attributed to the increase of plant biomass [50,51,52]
Our study suggested that the C and N cycles in the grassland ecosystem are determined by plant biomass, and by soil microbial activity
Summary
The grasslands in China cover an area of 3.92 million km and provide 9% to 16% of the total C in the world grasslands [1,2,3]. Natural grasslands of southern China cover an area of 79.58 million km, and probably have a high yield owning to good hydrothermal conditions [8], which can be an important C and N pool. Compound fertilizers or organic amendments affected grasslands C and N storage via increasing plant biomass [10,13,14]. Clipping was found to affect the grassland C and N storage via reducing plant biomass [9] and changing grass species [19]. The potentially dominant plants (i.e. usually larger than their neighbors) often lose a higher proportion of their biomass than their neighbors after clipping [9]
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