Vertebrate herbivore-induced changes in plants and soils: linkages to ecosystem functioning in a semi-arid steppe
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- Large grazing herbivores have been reported to determine the structure and function of grassland ecosystems. However, the ecological linkages between structure and functioning components have yet been thoroughly explored.
- Here, we test the hypothesis of the impact of grazing on soil nematode community (e.g. structure and composition) and linkages to ecosystem functioning (e.g. soil N mineralization and ANPP) via changes in pathways of plant community, soil nutrients and soil environment using a field experiment maintained for 5 years with seven levels of grazing intensity in the Inner Mongolian grassland.
- A structural equation model (SEM) with nematode abundances as response variables showed that plant-feeding and fungal-feeding nematodes were driven by changes in the plant community, and bacterial-feeding nematodes were affected by soil abiotic nutrients and environment, while omnivorous + carnivorous nematodes were altered by soil environment and bacterial-feeding nematodes. This indicates that the top-down control by grazing leads to bottom-up control in the soil food web.
- We found that grazing affected the ecosystem functioning via different pathways. Grazing effects soil N mineralization by changing plant community, soil nutrients, soil environment and nematodes community structure, while it affects ANPP by altering soil N mineralization and soil environment.
- Our findings could provide a better understanding of the responses of plants and soils to grazing and the linkages between structure and functioning of above-ground and below-ground in the semi-arid steppe.