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Context Several initiatives seek to increase the pace and scale of dry forest restoration and fuels reduction to enhance forest resilience to wildfire and other stressors while improving the quality and reliability of key ecosystem services. Ecological effects models are increasingly used to prioritize these efforts at the landscape-scale based on simulated treatment outcomes. Objectives Treatments are often simulated using uniform post-treatment target conditions or proportional changes to baseline forest structure variables, but do not account for the common objective of restoration to mimic the complex forest structure that was present historically which is thought to provide an example of structural conditions that contributed to ecosystem diversity and resilience. Methods We simulate spatially homogenous fire hazard reduction treatments along with heterogeneous restoration treatments in dry conifer forests to investigate how spatial complexity affects ecological indicators of (1) forest structural heterogeneity, (2) forest and watershed vulnerability to high-severity fire, and (3) feasibility of future prescribed fire use. Results Our results suggest that spatially explicit restoration treatments should produce similar wildfire and prescribed fire outcomes as homogeneous fuels reduction treatments, but with greater forest structural heterogeneity. The lack of strong tradeoffs between ecological objectives suggests the primary benefit of spatially complex treatments is to increase forest structural heterogeneity which may promote biodiversity. Conclusions We show that landscape-scale prioritization to maximize ecological benefits can change when spatially complex restoration treatments are modeled. Coupling landscape-scale management simulations and ecological effects models offers flexible decision support for conservation assessment, prioritization, and planning.

2Ecological restoration treatments are being implemented at an increasing rate in ponderosa pine 3 and other dry conifer forests across the western United States, via the USDA Forest Service's 4 Collaborative Forest Landscape Restoration (CFLR) program. In this program, collaborative 5 stakeholder groups work with National Forests (NFs) to adaptively implement and monitor 6 ecological restoration treatments intended to offset the effects of many decades of anthropogenic 7 stressors. We initiated a novel study to expand the scope of treatment effectiveness monitoring 8 efforts in one of the first CFLR landscapes, Colorado's Front Range. We used a 9 Before/After/Control/Impact framework to evaluate the short-term consequences of treatments 10 on numerous ecological properties. We collected pre-treatment and one year post-treatment data 11 on NF and partner agencies' lands, in 66 plots distributed across seven treatment units and 12 nearby untreated areas. Our results reflected progress toward several treatment objectives: treated 13 areas had lower tree density and basal area, greater openness, no increase in exotic understory 14 plants, no decrease in native understory plants, and no decrease in use by tree squirrels and 15 ungulates. However, some findings suggested the need for adaptive modification of both 16 treatment prescriptions and monitoring protocols: treatments did not promote heterogeneity of 17 stand structure, and monitoring methods may not have been robust enough to detect changes in 18 surface fuels. Our study highlights both the effective aspects of these restoration treatments, and 19 the importance of initiating and continuing collaborative science-based monitoring to improve 20 the outcomes of broad-scale forest restoration efforts. 21 22Running head: Ecological consequences of forest restoration treatments in Colorado 4 program included monitoring the effectiveness of the restoration treatments, but for each of the 49 CFLR-funded projects, the NFs and their collaborators were charged with developing their own 50 monitoring programs (Schultz et al. 2014). Few precedents existed to guide the CFLR projects in 51 this endeavor. The monitoring approach utilized by the Fire and Fire Surrogate study (FFS) at 12 52 sites across the US had some relevance, but FFS treatments tended to emphasize fuels reduction 53 rather than ecological restoration, were implemented in 'blocks' with replicated but relatively 54 small treatment and control units (~10 ha) at each site, and were monitored in a relatively 55

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