Abstract:

Aims: The combined impacts of climate change and human activities are likely to increase the land areas suitable for poisonous weeds, leading to rapid biodiversity loss and increasingly severe grassland degradation in the semi-arid region of Xinjiang. Enhanced understanding of the relationship between soil biomes and ecosystem multifunctionality can provide theoretical support for efforts to control the spread of poisonous weeds in Xinjiang. 

Methods: This study used a field experiment to explore the effects of nitrogen, water addition and mowing on soil biodiversity patterns, co-occurrence networks, and the relationship between diversity indices and ecosystem multifunctionality. This study adopted a randomized block trial design and set up eight treatments, which are no nitrogen, no watering, no mowing (CK), nitrogen addition (N treatment), watering (W treatment), mowing (M treatment), nitrogen × watering (NW treatment), nitrogen × mowing (NM treatment), watering × mowing (WM treatment), nitrogen × watering × mowing (NWM treatment). 

Results: (1) The Shannon-Wiener diversity index of soil bacteria differed significantly between the control, water addition, and nitrogen-mowing treatments. There were no significant differences between the diversity of soil fungi, nematodes, and arthropods in each treatment. (2) N, W, M, NW, and NM treatments all resulted in reduced complexity and connectivity of soil biological co-occurrence networks. WM and NWM treatments increased the complexity and connectivity of soil biological co-occurrence networks. (3) In the control, there was a significant and positive correlation between multidiversity and ecosystem multifunctionality (P < 0.01). In the NM treatment, there was a significant and negative correlation between multidiversity and ecosystem multifunctionality (P < 0.05). There was no correlation between multidiversity and ecosystem multifunctionality in the other treatments. Finally, soil bacterial diversity was most susceptible to the change of external environment. 

Conclusion: This study demonstrated that short-term nitrogen addition, watering, and mowing can weaken the relationship between soil biodiversity and ecosystem multifunctionality. These findings provide a theoretical basis for closer study of the mechanisms that affect the relationship between soil biodiversity and ecosystem multifunctionality through environmental changes caused by global climate change.

Key words: global change, poisonous weeds, microbes, soil fauna, ecosystem multifunctionality