This study was initiated to determine if herbivores increase or decrease the rate of nutrient cycling in oak savanna plant communities. Plant communities inside of exclosures had more above-ground biomass, which responds positively to increased nutrient availability, and less below-ground biomass than plant communities exposed to deer (Odocoileus virginianus) herbivory. Legumes and woody plants, which can affect N fixation rates and microsite characteristics, were shorter and had lower percent cover in plots exposed to deer herbivory than inside exclosures. The authors results support the hypothesis that herbivores indirectly decelerate N cycling by decreasing the abundance of plant species with nitrogen-rich tissues. However, other factors, such as disturbance from fire, may mediate herbivore effects on long-term changes in N and C pools. Herbivores may therefore indirectly control productivity, N cycling, and succession by consuming nitrogen-fixing and woody plants that have strong effects on plant resources.
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