The changes in soil extractable N and P resulted in higher soil N/P ratios, suggesting that reindeer could drive the vegetation toward P-limitation.
This research highlights the importance of including both the elements N and P and conducting studies along environmental gradients in order to better understand the interactive effects of herbivory and habitat fertility on nutrient cycling and primary production.
Proposed explanations for these contradictory results include the importance of other factors than initial nutrient availability in determining the net effect of herbivores on soil N, such as trampling-induced soil compaction or lateral transport of nutrients between habitats (Sitters and Olde Venterink ).
In addition, a recent model analysis predicts that herbivory will decrease microbial activity by reducing C supply to the soil through consumption of plant biomass and will thus have a negative effect on N availability at low plant C/N ratios through a decrease in mineralization rates and a positive effect at higher plant C/N ratios through a decrease in immobilization rates (Cherif and Loreau ).
Mean annual temperature at the site was −3.3°C based on local loggers, and the average precipitation at the nearest climatic station (Kautokeino) is 389 mm/year.
We conducted the study across a reindeer fence, established in the 1960s to prevent reindeer from entering their winter ranges during summer.
We want to emphasize that grazing in this study includes trampling on the vegetation in its definition.
for a description of topographic gradients in the arctic).
MC, RG, JO contributed to design of the study and writing of the paper.).
The main mechanism by which they do this is by changing the quantity and/or quality of resources supplied to the soil, affecting the rate of organic matter decomposition and soil nutrient availability (Mc Naughton ).