Murray Et Al. 1 Running Head: Ungulates and N Availability in Space 1

10 Spatial heterogeneity of soil resources, particularly nitrogen availability, affects herbaceous-layer 11 cover and diversity in temperate forest ecosystems. Current hypotheses predict that ungulate 12 herbivores influence nitrogen availability at the stand scale, but how ungulates affect nitrogen 13 availability at finer spatial scales that are relevant to the herb-layer is less understood. We tested 14 the hypothesis that ungulate exclusion reduces the spatial complexity of nitrogen availability at 15 neighborhood scales (1-26m) apart from mean stand scale effects. This outcome was expected 16 due to a lack of ungulate nitrogenous waste deposition within exclosures and seasonally variable 17 ungulate habitat use. To test this hypothesis we examined spatial patterning of ammonium and 18 nitrate availability, herb-layer cover and diversity, and under-canopy solar radiation using 19 geostatistical models. Our study sites included 6 stands of eastern hemlock (Tsuga canadensis) 20 forest: 3 where white-tailed deer (Odocoileus virginianus) were excluded and 3 that were 21 accessible to deer. Where deer were present patch sizes of ammonium availability, cover, and 22 diversity were smaller compared to deer exclosures whereas mean site level effects were not 23 significant. Within deer exclosures cover and solar radiation were more similar in patch size than 24 were cover and nitrogen availability. Our results suggest that browsing ungulates affect spatial 25 patterns of herb-layer cover and diversity through the excretion of nitrogenous wastes in small, 26 discrete patches. Ungulate-excreted nitrogen deposition and herbivory was concentrated in the 27 dormant season, allowing herb-layer plants a greater opportunity to benefit from nitrogen 28 additions. Therefore, the impact of ungulates on nitrogen cycling in forest ecosystems varies 29 with spatial scale and the seasonal timing of ungulate impacts. In this way, ungulates may 30 function as a seasonally-dependent link between fine scale and landscape level ecological 31 processes. 32