Working paper 23: Guidelines for managing small mammals in restored ponderosa pine forests of northern Arizona

Restoration thinning and burning treatments in southwestern ponderosa pine (Pinus ponderosa) forests are designed to both reduce the risk of wildfire and restore ecosystem functions and structure, including maintaining or reestablishing habitat for wildlife populations. However, we found limited quantitative data regarding wildlife responses to restoration treatments and changes in forest structure because most previous studies were conducted at small temporal and spatial scales, and they generally focused on bird species (Kalies et al. 2010). In addition, although habitat components, such as Gambel oak (Quercus gambelii), large-diameter trees, snags and downwood, are thought to be important to wildlife, there is debate about treatment targets on the landscape (Abella et al. 2006, Noss et al. 2006). In this ERI Working Papers , we present the results of a study that assessed small mammal responses to treatments--responses previously unexamined at the community level or at large temporal and spatial scales in southwestern ponderosa pine forests

Small mammal community maintains stability through compensatory dynamics after restoration of a ponderosa pine forest

Ecosystem stability has been of increasing interest in the past several decades as it helps predict the consequences of anthropogenic disturbances on ecosystems. Species may exhibit stability through compensation, with greatly fluctuating populations year to year but a consistent density response over time. Stability is increased when species with similar functional roles compensate for one another by responding differently to environmental change. In restoration projects, the objective is to restore stability by altering ecosystem composition, structure, and function to resemble natural (‘‘reference’’) conditions. We assessed the success of ecological restoration treatments by examining the structural and functional responses of the small mammal community before and after treatment, and compared to reference conditions. We used Royle density models to examine the responses of eight species of small mammals to restoration (thinning) treatments in ponderosa pine forests to determine if the community maintained total density, biomass, and function (represented by ectomycorrhizal fungi dispersion) after disturbance. Community composition differed in each of 6 years following treatment, but total density and biomass remained constant, suggesting the community is a stable prey base for predators. In addition, goldenmantled ground squirrels (Spermophilus lateralis) and gray-collared chipmunks (Tamias cinereicollis) appeared to play a similar role in dispersing ectomycorrhizal fungi across different forest structures. Both total species density and biomass were greater after thinning than in unthinned stands, and were similar to reference stands. These results suggest that although species composition changes from year to year after disturbance, restoration treatments can maintain ecosystem stability in terms of small mammal community-level properties

The Effects of Forest Management on Small Mammal Community Dynamics in Southwestern Ponderosa Pine Ecosystems

In the southwestern United States, ponderosa pine (Pinus ponderosa) forests have been decreasing in biological diversity for the past century. Today's forests are characterized by dense stands of small-diameter trees that are susceptible to stand-replacing crown fires. There is now an emphasis on ecological restoration in the Southwest, whereby forests are thinned to reduce fuel content so that the natural fire regime can be reintroduced. However, given the multiple impacts humans have had on the landscape over the past 100 years, it is unclear whether thinning and burning treatments will restore all aspects of ecosystem health. Given this uncertainty, managers and stakeholders want information on the impacts of treatments on multiple ecosystem components, including wildlife. I used meta-analysis to compare effects of restoration treatments on wildlife species in southwestern conifer forests. Thinning and burning treatments had positive effects on most small mammals and passerine bird species reported in 25 studies suitable for meta-analysis; overstory removal and wildfire resulted in an overall negative response. I recommend that managers implement thinning and burning treatments, but that future research efforts focus on long-term responses of species at larger spatial scales and target species for which there is a paucity of data. iii No comprehensive analysis of the small mammal community in response to restoration treatments at large scales has been conducted in ponderosa pine forests. Small mammals are important in forest ecosystems in serving as prey, recycling nutrients, dispersing fungal spores and seeds, and aerating soils. During 2006-2009, I trapped eight species of small mammals at 294 sites in northern Arizona, and used occupancy modeling to determine wildlife responses to habitat. The most important habitat variables in predicting small mammal community occupancy were pine basal area, treatment intensity (percent of trees removed and time since treatment), the number and length of time slash piles are left on the ground, rock cover, and snags >40cm diameter. The average occupancy of all species was positively related to thinning treatment and slash. No one treatment benefitted all species, but rather an arrangement of dense and open stands across the landscape with heterogeneity in fine-scale features is likely the best management approach for restoring and maintaining a diverse small mammal community. Similarly, community composition differed in each of 6 years following treatment, but total density remained constant. Total species densities were significantly lower in stands with dense conditions than in stands with more open structural conditions similar to those of presettlement times, which had similar small mammal densities as the thinning treatments. In addition, tassel-eared squirrels (Sciurus aberti), golden-mantled ground squirrels (Spermophilus lateralis), and gray-collared chipmunks (Tamias cinereicollis) appeared to play a functionally redundant role in dispersing ectomycorrhizal fungi across different stand structures. These results iv suggest that restoration treatments can maintain ecosystem stability in terms of small mammal community structure and function. Finally, I found that the rapid assessment, occupancy and density modeling approach was highly effective in evaluating the response of the small mammal community to treatment and other habitat attributes. Particularly in the arid Southwest, most small mammal population studies end up primarily tracking precipitation patterns, but I showed a lack of a year effect by all species. Although this study was a big effort, it obtained more reliable, repeatable results for a greater number of species than many equally-intensive small mammal studies with similar objectives, which relied on mark-recapture methods and density estimation. I suggest this design be utilized in other studies that grapple with high variability and large spatial and temporal scales in assessing general impacts of treatments or habitat change on wildlife species

Systematic Review – Final: How do thinning and burning treatments in southwestern conifer forests in the United States affect wildlife density and population performance?

The aim of this review is to examine whether thinning and burning treatments in conifer forests in the southwestern United States affect wildlife distribution, abundance, and population performance

Working paper 18: Prescribed and wildland use fires in the southwest: Do frequency and timing matter?

Support for the use of prescribed fire and wildland fire use has increased in the Southwest in recent decades. However, the frequency and seasonality of these contemporary fires is typically different than historical fires, which burned during late spring and early summer in the driest and windiest time of the year. Contemporary changes in the landscape, including unprecedented fuel loads and human development in and around forests, now limit the ability to use fire during those times of the year. Most managed fire now occurs outside the windy fire season because it is safer and allows managers to provide greater protection to susceptible cultural or natural resources, such as historic structures or dry snags

Tamm Review: Are fuel treatments effective at achieving ecological and social objectives? A systematic review.

The prevailing paradigm in the western U.S. is that the increase in stand-replacing wildfires in historically frequent-fire dry forests is due to unnatural fuel loads that have resulted from management activities including fire suppression, logging, and grazing, combined with more severe drought conditions and increasing temperatures. To counteract unnaturally high fuel loads, fuel reduction treatments which are designed to reduce fire hazard and improve overall ecosystem functioning have been increasing over the last decade. However, until recently much of what we knew about treatment effectiveness was based on modeling and predictive studies. Now, there are many examples of wildfires burning through both treated and untreated areas, and the effectiveness of treatments versus no action can be evaluated empirically. We carried out a systematic review to address the question: Are fuel treatments effective at achieving ecological and social (saving human lives and property) objectives? We found 56 studies addressing fuel treatment effectiveness in 8 states in the western US. There was general agreement that thin + burn treatments had positive effects in terms of reducing fire severity, tree mortality, and crown scorch. In contrast, burning or thinning alone had either less of an effect or none at all, compared to untreated sites. Most studies focused on carbon storage agreed that treatments do not necessarily store more carbon after wildfire, but result in less post-wildfire emissions and less carbon loss in a wildfire due to tree mortality. Understory responses are mixed across all treatments, and the response of other ecological attributes (e.g., soil, wildlife, water, insects) to treatment post-wildfire represents an important data gap; we provide a detailed agenda for future research. Overall, evidence is strong that thin + burn treatments meet the goal of reducing fire severity, and more research is needed to augment the few studies that indicate treatments protect human lives and property

A meta-analysis of management effects on forest carbon storage

<p>Forest management can have substantial impacts on ecosystem carbon storage, but those effects can vary significantly with management type and species composition. We used systematic review methodology to identify and synthesize effects of thinning and/or burning, timber harvesting, clear-cut, and wildfire on four components of ecosystem carbon: aboveground vegetation, soil, litter, and deadwood. We performed a meta-analysis on studies from the United States and Canada because those represented 85% of the studies conducted worldwide. We found that the most important variables in predicting effect sizes (ratio of carbon stored in treated stands versus controls) were, in decreasing order of importance, ecosystem carbon component, time since treatment, and age of control. Management treatment was the least important of all the variables we examined, but the trends we found suggest that thinning and/or burning treatments resulted in less carbon loss than wildfire or clear-cut. This finding is consistent with recent modeling studies indicating that forest management is unimportant to long-term carbon dynamics relative to the effects of large-scale natural disturbances (e.g., drought, fire, pest outbreak). However, many data gaps still exist on total ecosystem carbon, particularly in regions other than North America, and in timber production forests and plantations.</p

Low impact siting for wind power facilities in the Southeast United States

Abstract Although installed wind power generation capacity in the United States reached 132 GW in 2021, more than quadruple the capacity in 2008, a noticeable void exists in the Southeast. Scant wind power development in this region is due to relatively poorer wind resources, other competitive energy sources, and political opposition. However, the dramatic increases in wind turbine hub height, which allow harvesting the faster wind speeds that occur farther from the ground, combined with a growing sense of urgency to develop renewable energy, point to a near future with significant wind development everywhere, including the Southeast. Nevertheless, the enthusiasm for replacing fossil fuels with renewable sources is tempered by fears that the vast land requirements of utility‐scale wind farms may disrupt valuable ecosystems. In this paper, we identify the areas where installed wind power capacity is least likely to disrupt wildlife and sensitive natural areas in the southeastern United States. The generated maps exclude geographic areas unsuitable for wind power development due to environmental concerns or technical considerations corresponding to five categories. The resulting geospatial product suggests that even after removing sizable areas from consideration, there is significant land for wind development to meet the Southeast's energy needs and clean energy goals

Remotely sensed habitat quality index reliably predicts an umbrella species presence but not demographic performance: A case study with open pine forests and red-cockaded woodpeckers

Remote sensing data can be a powerful and cost-effective method for determining the extent, composition, and structure of ecosystems across large areas. To use this tool for effective conservation of individual species, we need to test the assumption that remotely sensed habitat indices correspond to both patch suitability (i.e., presence) and value (i.e., demographic rates) for the species reliant on those habitats. We built an open pine habitat quality index (HQI) from remotely sensed spectral data to identify the condition of pine stands. We correlated the HQI with presence, group size, and fledgling production of an avian species (red-cockaded woodpecker, Dryobates (=Picoides) borealis, RCW) associated with longleaf pine (Pinus palustris) using Bayesian logistic regressions and structural equation models. The HQI was correlated with RCW cavity tree and foraging area presence, with 10.8 and 16.0 increased odds of RCW presence with each unit increase in the HQI, respectively. However, the HQI was not correlated with RCW demographic performance. Given that RCWs are an umbrella species and are currently limited by habitat, that the HQI successfully identifies areas of higher quality habitat for RCW is useful for conservation planning. Improving the specificity of the remotely sensed index could improve the link between the HQI and RCW demographic performance, but might limit its application to RCW, instead of the entire open pine endemic community. Our study suggests that linking generalized habitat indices to species habitat suitability is possible and strengthens the justification for their use in cost-effective, large-scale conservation of imperiled ecosystems