Short-term ecological consequences of collaborative restoration treatments in ponderosa pine forests of Colorado

Abstract

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

Overstory Structure and Surface Cover Dynamics in the Decade Following the Hayman Fire, Colorado

“…The vast majority of trees in both the 0-10 and the 10-20 cm DBH classes were killed, as were the vast majority of Douglas-fir trees. The changes we observed in moderate-severity areas were in line with those brought about elsewhere by moderate-severity wildfire [15,31], and by aggressive hand and mechanical thinning treatments [48,50,51]. Meanwhile, high-severity areas experienced the greatest change in live overstory structure; in these areas, burning transformed dry conifer forests into herb-dominated openings devoid of overstory trees, just as it has done across the west [15,18,31].…”

“…Litter and duff typically blanket most of the ground surface in dry conifer forests of the west [21,51,68], and prior to the Hayman Fire, our study site was no exception. Although the Hayman Fire consumed some of the pre-fire litter and duff in low-severity areas, it did not alter their cover in the first post-fire year relative to pre-fire levels.…”

“…They also experienced no change in large snag density and little to no change in surface cover attributes like mineral soil cover, litter and duff cover, and herb cover. As in unburned areas, thinning or prescribed fire treatments could be implemented in low-severity areas in the first few post-fire years or decades to move live overstory structure closer to HRV [48,50,51]. Such treatments could also promote large snag and herb abundance.…”

Mixed-Severity Fire Fosters Heterogeneous Spatial Patterns of Conifer Regeneration in a Dry Conifer Forest

“…However, residual tree densities were lower than those reported for undisturbed forests in the region [31,37,63], as well as for recently restored forests [31,63]. Basal area and canopy cover values following mixed-severity fire were also within the range of those reported for restored forests [31,63].…”

Have we been successful? Monitoring horizontal forest complexity for forest restoration projects

“…To further corroborate the use of aerial image analysis to map the canopy, we compared the canopy cover quantified using aerial image analysis to field‐measured canopy cover for a subset of five treatment units pre‐ and post‐treatment ( n = 10), with each observation treated as independent for the purposes of this analysis. The field‐measured canopy cover was quantified by Briggs et al (unpublished raw data) using between three and nine permanent 100 m intercept transects per treatment unit. The mean percent of transect length covered by canopy was calculated for each treatment unit, and simple linear regression was used to statistically compare the canopy cover quantified using aerial imagery (%) to the field‐measured canopy cover (%).…”