Brian Palik

• US Forest Service

Silviculture is the central discipline of forestry. It has always been influenced by changes in social and environmental conditions. Much has been accomplished in terms of advancing silviculture, including the culture, scope, and the goals and values it supports. However, we see that trends that initiated or strengthened during the last three decad...

Climate-driven stressors, non-native insects, and emerging diseases increasingly impact forest health across the Great Lakes region. Forest management strategies are required to mitigate these impacts. We examined one strategy, tree planting for adaptation to climate and emerald ash borer (hereafter referred to as adaptation plantings), as an appro...

Group selection and small patch cutting are widely viewed as more aesthetically acceptable alternatives to clearcutting for regenerating tree species of low shade tolerance, and they may enhance resilience in the face of climate change. However, little evidence is available on how production rates compare with those of other silvicultural systems....

Heterogeneous spatial patterns are an important characteristic of forests and central to forest functioning and resilience. Old forests typically have complex structures and provide useful starting points from which to understand processes assembling forest communities and in turn managing for resilience. In the U.S. Lake States, extant old growth...

Threats to the future function of forested ecosystems and stability of ecosystem service provisioning due to global change have motivated climate-adaptive forest management strategies that include various forms of tree planting termed "adaptation plantings". Despite the emergence of these strategies, less is known as to how foresters and other natu...

Forest assisted migration (FAM) is the movement of tree species or genotypes to locations that are projected to be climatically suitable for future growth and survival. FAM can be an integral component of climate adaptation projects. An example of such a project is the Red Pine Adaptive Silviculture for Climate Change (Red Pine ASCC) experiment in...

Forest assisted migration (FAM) is the movement of tree species or genotypes to habitat believed to be characterized by the climate of the source population. FAM can be an integral component of climate adaptation projects. An example of such a project is the Red Pine Adaptive Silviculture for Climate Change (Red Pine ASCC) experiment in northern Mi...

Tree planting is increasingly being adopted as a strategy to address global change, including mitigation, adaptation, and restoration. Although reforestation has long been central to forest management, the desired outcomes of traditional and emerging tree-planting strategies face barriers linked to a lack of ecological diversity in forest nurseries...

Uncertainty surrounding global change impacts on future forest conditions has motivated the development of silviculture strategies and frameworks focused on enhancing potential adaptation to changing climate and disturbance regimes. This includes applying current silvicultural practices, such as thinning and mixed-species and multicohort systems, a...

Height growth in trees is expensive in terms of the amount of stem tissue required to maintain productive tissue in sunlight. However, shifting allocation from stem support to leader growth and foliage production may allow trees to minimize shading effects on photosynthesis, especially for shorter trees within the population. This hypothesis was ev...

Black ash (Fraxinus nigra) forests, which cover over 1.2 million hectares in the Great Lakes Region, are threatened by emerald ash borer (EAB; Agrilus planipennis), which is eliminating native populations of ash throughout the region. Understanding the contribution of black ash wetlands to local and regional species richness is critical in forming...

Height growth in trees is expensive in terms of the amount of stem tissue required to maintain productive tissue in sunlight. However, shifting allocation from stem support to leader growth and foliage production may allow trees to minimize shading effects on photosynthesis, especially for shorter trees within the population. This hypothesis was ev...

Uncertainty and emerging threats associated with climate change necessitate the development of new approaches for managing forest ecosystems. To address this need the Adaptive Silviculture for Climate Change (ASCC) Network was established to examine the efficacy of three climate adaptation strategies in important forest types across North America:...

There is increasing momentum to implement conservation and management approaches that adapt forests to climate change so as to sustain ecosystem functions. These range from actions designed to increase the resistance of current composition and structure to negative impacts to those designed to transition forests to substantially different character...

Black ash (Fraxinus nigra Marsh.) forests of north-central North America are currently threatened by the non-native emerald ash borer (Agrilus planipennis, EAB). Despite the wide distribution of F. nigra ecosystems, and the concern over EAB impact, little is known about their structure and natural stand dynamics. We sampled six old-growth F. nigra...

Black ash wetlands cover approximately 1.2 million ha of wetland forest in the western Great Lakes region, providing critical habitat for wildlife. The future of these wetlands is critically threatened by a variety of factors, including emerald ash borer (Agrilus planipennis; emerald ash borer [EAB]), which has been eliminating native populations o...

Do trees adjust support costs to the stem in order to maintain or boost allocation to foliage to compete for light? This question was addressed with data collected from three, long-term studies investigating the growth effects of controlled levels of competition for Alnus rubra , Pseudotsuga menziesii , and Pinus resinosa . Costs and benefits of ma...

In addition to long-standing concerns about sustaining forest productivity, maintaining forest ecosystems under changing conditions and emerging threats has become increasingly important when planning forest management. With the aim of understanding effects of management on both productivity and recovery, we quantified the 25-year impact of varying...

Seasonal ponds are small, isolated wetlands with variable hydrology, often occurring embedded in upland forests, which provide habitat for amphibians and invertebrates uniquely adapted to fishless waters. Seasonal ponds are challenging to identify due to their small size, ephemeral hydrology, diverse vegetation, and occurrence across a range of set...

Organic matter (OM) is an integral part of site productivity for a forest, and understanding the effects of OM removal on various forms of carbon (C) cycling is important for land managers and for policy makers. In this study, we utilized the Lake States Long-Term Soil Productivity (LTSP) study sites, located along a gradient in soil texture (clay,...

We compiled data from several independent, long-term silvicultural studies on USDA Forest Service experimental forests across a latitudinal gradient in the northeastern and north-central U.S.A. to evaluate factors influencing aboveground live-tree carbon sequestration and mortality. Data represent five sites with more than 70,000 repeated tree reco...

We used dendrochronological methods and remnant fire-scarred red pines (Pinus resinosa Ait.) to reconstruct historical fire regime characteristics and relate these findings to past climate, human land use changes, and vegetation for a landscape in northern Minnesota, USA. A total of 314 fire scars were dated, representing 56 unique fire events from...

The Adaptive Silviculture for Climate Change (ASCC) project was developed to test ecosystem-specific adaptation approaches. The first ASCC trial was installed on the Cutfoot Experimental Forest (CEF) in northern Minnesota, USA, in 2014. Three adaptation treatments (resistance, resilience, and transition), along with a no action control, were tested...

Forest residues and logging slash from pre-commercial forest thinning and regeneration harvests are a potential feedstock for bioenergy production but there has been a concern about the impact of residue removal on forest soil C and N. This study aimed to address such by conducting two meta-analyses using the data available from published literatur...

Black ash (Fraxinus nigra) is native to lowland forests of the western Great Lakes region, USA, where it often comprises a majority of trees. Like all native ash in North America, black ash is threatened by emerald ash borer (EAB; Agrilus planipennis), but the impacts from EAB mortality may be particularly severe in these forests given the foundati...

The emerald ash borer (EAB) has killed ash species (Fraxinus L.) in much of eastern North America, but it has yet to reach the vast ash wetlands in northern Minnesota, USA. In these wetlands, a single species, black ash (Fraxinus nigra Marsh.) comprises a majority of trees and has a foundational role in controlling ecosystem function. Given the lik...

Black ash (Fraxinus nigra) wetlands are widespread, forested landscape features in the western Great Lakes region. However, the future of these ecosystems is threatened due to impending spread of the invasive emerald ash borer (EAB), which results in tree mortality, decreased transpiration, and potential shifts to wetter, non‐forested conditions. T...

Sustaining the structure, function, and services provided by forest ecosystems in the face of changing climate and disturbance regimes represents a grand challenge for forest managers and policy makers. To address this challenge, a range of adaptation approaches have been proposed centered on conferring ecosystem resilience and adaptive capacity; h...

Warming climate and resulting declines in seasonal snowpack have been associated with drought stress and tree mortality in seasonally snow‐covered watersheds worldwide. Meanwhile, increasing forest density has further exacerbated drought stress due to intensified tree–tree competition. Using a uniquely detailed data set of population‐level forest g...

Since its inception in 1973, the National Silviculture Workshop (NSW) has brought together forest managers and researchers from across the USDA Forest Service, and more recently our university and other partners, to provide a forum for information sharing and science advancements in silviculture. The 2019 NSW focused specifically on this partnershi...

Contemporary forest management is increasingly focused on maintaining ecosystem function and services including biodiversity conservation. As a result, harvest guidelines related to retention of live trees and woody biomass (fine and coarse residue arising from harvesting) have been developed to provide benefits for wildlife, but there is much unce...

Increasing heat and aridity in coming decades is expected to negatively impact tree growth and threaten forest sustainability in dry areas. Maintaining low stand density has the potential to mitigate the negative effects of increasingly severe droughts by minimizing competitive intensity. However, the direct impact of stand density on the growing e...

The invasion by emerald ash borer (Agrilus planipennis) of extensive black ash wetlands in the upper Great Lakes region of North America is expected to alter plant community structure and composition and, therefore, abiotic factors like temperature and hydrology. We conducted two experiments to examine how changes in leaf litter could alter ecosyst...

In recent decades, a paradigm shift in forest management and associated policies has led to greater emphasis on harvest practices that retain mature, overstory trees in forest stands that would otherwise be clear‐cut. While it is often assumed that the maintenance of compositional and structural complexity, such as that achieved through retention f...

Black ash (Fraxinus nigra) wetlands are an important economic, cultural, and ecological resource in the northern Great Lake States, USA, and are threatened by the invasive insect, emerald ash borer (Agrilus planipennis Fairmmaire [EAB]). EAB-induced ash mortality can increase air temperatures, alter understory vegetation communities, and modify wet...

Across the boreal forest in North America, the black spruce (Picea mariana) cover type is ecologically and economically important, occupying roughly 10 percent of Minnesota’s, USA 17.4 million acres (7.0 million hectares) of forestland. Traditionally managed through clearcut regeneration harvests, alternative silvicultural systems are being increas...

Disturbance is a central driver of forest development and ecosystem processes with variable effects within and across ecosystems. Despite the high levels of variation in disturbance severity often observed in forests following natural and anthropogenic disturbance, studies quantifying disturbance impacts often rely on categorical classifications, t...

Aerial discrete return LiDAR (Light Detection And Ranging) technology (ALS-Aerial Laser Scanner) is now widely used for forest characterization due to its high accuracy in measuring vertical and horizontal forest structure. Random and systematic errors can still occur and these affect the native point cloud, ultimately degrading ALS data accuracy,...

Variable retention harvesting (VRH) systems have gained wide use in many different forest types across the globe, but largely have been implemented in forests characterized by severe, infrequent disturbance regimes. There has been less attention given to developing VRH approaches in forests that are characterized as having a mixed-severity disturba...

Reducing forest stand density through silvicultural thinning has demonstrated potential to mitigate drought impacts on growth; however, less has been studied on how changes in stand structure created by different thinning methods influence forest growth responses to drought. This research examined the growth responses to drought of natural-origin r...

Forest soil ecosystems can be negatively affected by intensive biomass harvesting due to losses of organic inputs and soil compaction, ultimately leading to reduced forest productivity. In this research, we revisited a site from the North American Long-Term Soil Productivity study located on a sandy Spodosol within the Huron National Forest in Mich...

Peatlands, which account for approximately 15% of land surface across the arctic and boreal regions of the globe, are experiencing a range of ecological impacts as a result of climate change. Factors that include altered hydrology resulting from drought and permafrost thaw, rising temperatures, and elevated levels of atmospheric carbon dioxide have...

Northern hardwood stands in the Great Lakes region are often managed using single-tree selection, which generally favors regeneration of shade-tolerant species, especially sugar maple (Acer saccharum Marsh.) and may reduce regeneration of midtolerant and shade-intolerant species. These forests also tend to have lower microsite diversity than old-gr...

Emerald ash borer (EAB; Agrilus planipennis Fairmaire, 1888) has been a persistent disturbance for ash forests in the United States since 2002. Of particular concern is the impact that EAB will have on the ecosystem functioning of wetlands dominated by black ash (Fraxinus nigra Marsh.). In preparation, forest managers need reliable and complete map...

Accurate downed woody debris (DWD) volume or mass estimates are needed for numerous applications such as fuel loading, forest carbon, and biodiversity/habitat assessments. The line-intersect sampling (LIS) method of inventorying DWD is widely used in forest inventories and ecological studies because it is time-efficient and unbiased. Despite its wi...

The black spruce cover type occupies roughly 10% of Minnesota’s 7 million hectares of forestland, and is an important species, both ecologically and economically. A clearcut regeneration harvest is the main silvicultural system in black spruce in this region. The effects of managing black spruce with alternative silvicultural methods in the Lake St...

Widespread changes in arctic and boreal Normalized Difference Vegetation Index (NDVI) values captured by satellite platforms indicate that northern ecosystems are experiencing rapid ecological change in response to climate warming. Increasing temperatures and altered hydrology are driving shifts in ecosystem biophysical properties that, observed by...

Extended rotations have been suggested as a strategy for balancing timber production and ecological objectives. By lengthening the period of stand development, extended rotations may increase tree size inequality and other elements of structural complexity, thus reducing the disparity between managed and old-growth stands. A potential limitation of...

Gradient studies of wetland forests have inferred that competition from upland tree species confines waterlogging-tolerant tree species to hydric environments. Little is known, however, about competition effects on individual-tree growth along stress gradients in wetland forests. We investigated tree growth and competition in mixed-species stands r...

The arrival and spread of emerald ash borer (EAB) across the western Great Lakes region has shifted considerable focus towards developing silvicultural strategies that minimize the impacts of this invasive insect on the structure and functioning of black ash (Fraxinus nigra) wetlands. Early experience with clearcutting in these forests highlighted...

The emerald ash borer (EAB) is rapidly spreading throughout eastern North America and devastating ecosystems where ash is a component tree. This rapid and sustained loss of ash trees has already resulted in ecological impacts on both terrestrial and aquatic ecosystems and is projected to be even more severe as EAB invades black ash-dominated wetlan...

In the past several decades, a trend in forestry and silviculture has been toward promoting complexity in forest ecosystems, but how complexity is conceived and described has shifted over time as new ideas and terminology have been introduced. Historically, ecologically-focused silviculture has focused largely on manipulation of structural complexi...

Many studies have examined short-term changes in understory vegetation following prescribed burning. However, knowledge concerning longer term effects on both forest understory and overstory vegetation is lacking. This investigation was initiated to examine changes in understory (herbaceous and shrub) and overstory species composition almost four d...

When management for old-growth characteristics in eastern forests first began to be discussed in the late twentieth century, there was skepticism from some quarters as to whether it was a desirable or even a feasible idea. Old growth will recover on its own. Why not just let nature take its course? There were also those who saw little value in mana...

We measured total soil CO2 efflux (RS) and efflux from the forest floor layers (RFF) in red pine (Pinus resinosa Ait.) stands of different ages to examine relationships between stand age and belowground C cycling. Soil temperature and RS were often lower in a 31-year-old stand (Y31) than in 9-year-old (Y9), 61-year-old (Y61), or 123-year-old (Y123)...

Prescribed fire is increasingly viewed as a valuable tool for reversing ecological consequences of fire suppression within fire-adapted forests. While the use of burning treatments in northern temperate conifer forests has received considerable attention, the long-term (>10 year) effects on understory composition and dynamics have not been quantifi...

Structural complexity is widely recognized as an inherent characteristic of unmanaged forests critical to their function and resilience, but often reduced in their managed counterparts. Variable retention harvesting (VRH) has been proposed as a way to restore or enhance structural complexity in managed forests, and thereby sustain attendant biodive...

The group selection method can potentially increase the proportion of shade-intolerant and midtolerant tree species in forests dominated by shade-tolerant species, but previous results have been variable, and concerns have been raised about possible effects on forest fragmentation and forest structure. Limited evidence is available on these issues...

A rare, stand-replacing fire in northern Minnesota, USA provided the opportunity to compare the effects of wildfire and timber harvesting in two peatland forest communities, nutrient-poor black spruce (Picea mariana) bogs (BSB) and nutrient-rich tamarack (Larix laricina) swamps (RTS). We found the response between the two communities and their corr...

An understanding of long-term patterns of forest structural and compositional development is critical for anticipating management outcomes and developing appropriate silvicultural strategies for restoring complex forest conditions. In most cases, this information comes from stand-level assessments; however, the impacts and outcomes of management an...

Forests around the world are experiencing increasingly severe droughts and elevated competitive intensity due to increased tree density. However, the influence of interactions between drought and competition on forest growth remains poorly understood. Using a unique dataset of stand-scale dendrochronology sampled from 6405 trees, we quantified how...

Forest managers in the United States must respond to the need for climate-adaptive strategies in the face of observed and projected climatic changes. However, there is a lack of on-the-ground forest adaptation research to indicate what adaptation measures or tactics might be effective in preparing forest ecosystems to deal with climate change. Natu...

The emerald ash borer (EAB; Agrilus planipennis) is an invasive beetle that causes almost complete mortality of ash trees (Fraxinus spp.) in North America and Europe. Northern temperate wetlands, where black ash (F. nigra) is a dominant and foundation species, will likely undergo dramatic shifts after EAB invasion. Utilizing published knowledge on...

Recent emphasis on increasing structural complexity and species diversity reflective of natural ecosystems through the use of retention harvesting approaches is coinciding with increased demand for forest-derived bioenergy feedstocks, largely sourced through the removal of harvest residues associated with whole-tree harvest. Uncertainties about the...

Soil functions that control plant resource availability can be altered by management activities such as increased organic matter (OM) removal and soil compaction during forest harvesting. The Long Term Soil Productivity study was established to evaluate how these practices influence soil and site productivity using experimental treatments that span...

When an invasive organism targets a dominant tree species, it can trigger unprecedented shifts in forest plant communities. Emerald ash borer (EAB; Agrilus planipennis Fairmaire), an invasive insect that kills by girdling trees, represents a significant threat to North American Fraxinus (ash) species. EAB has already decimated many Fraxinus populat...

In the debate over global warming, treeline position is considered an important ecological indicator of climate change. Currently, analysis of upward treeline shift is often based on various spatial data processed by geomatic techniques. In this work, considering a selection of 31 reference papers, we assessed how the scientific community is using...

Prescribed fire is widely used for ecological restoration and fuel reduction in fire-dependent ecosystems, most of which are also prone to drought. Despite the importance of drought in fire-adapted forests, little is known about the cumulative effects of repeated prescribed burning on tree growth and related response to drought. Using dendrochronol...

Retention harvesting, an approach that intentionally retains legacy features such as mature overstory trees, provides options for achieving ecological objectives. At the same time, retained overstory trees may compete with the nearby recovering understory for resources, and much remains to be learned about potential trade-offs with regeneration obj...

Timber harvest can adversely affect forest biota. Recent research and application suggest that retention of mature forest elements (‘retention forestry’), including unharvested patches (or ‘aggregates’) within larger harvested units, can benefit biodiversity compared to clearcutting. However, it is unclear whether these benefits can be generalized...

Climate models predict increasing drought intensity and frequency for many regions, which may have negative consequences for tree recruitment, growth, and mortality, as well as forest ecosystem services. Furthermore, practical strategies for minimizing vulnerability to drought are limited. Tree population density, a metric of tree abundance in a gi...

An understanding of long-term patterns of forest structural and compositional development is critical for anticipating management outcomes and developing appropriate silvicultural strategies for restoring complex forest conditions. In most cases, this information comes from stand-level assessments; however, the impacts and outcomes of management an...

Fraxinus nigra Marsh. (black ash), a dominant tree species of wetland forests in northern Minnesota, USA, is imperiled by the invasive insect emerald ash borer (EAB; Agrilus planipennis Fairmaire, 1888). Regeneration of associated tree species is generally low in F.nigra forests and could be impacted further by climate change. Proactive management...

Question Resource availability and its influence on tree‐to‐tree interactions are expected to change over the course of forest stand development, but the rarity of long‐term data sets has limited examinations of neighbourhood crowding over extended time periods. How do a history of neighbourhood interactions and population‐level dynamics, including...

Questions Does the increase in disturbance associated with removing harvest residues negatively impact biodiversity and resilience in aspen‐dominated forest ecosystems? How do responses of functional diversity measures relate to community recovery and standing biomass? Location Aspen ( Populus tremuloides, Michx.) mixedwood forests in Minnesota an...

Intensive forest biomass harvesting, or the removal of harvesting slash (woody debris from tree branches and tops) for use as biofuel, has the potential to negatively affect the soil microbial community (SMC) due to loss of carbon and nutrient inputs from the slash, alteration of the soil microclimate, and increased nutrient leaching. These effects...

Concerns about loss of biodiversity and structural complexity in managed forests have recently increased and led to the development of new management strategies focused on restoring or maintaining ecosystem functions while also providing wood outputs. Variable retention harvest ( VRH ) systems, in which mature overstorey trees are retained in vario...

Red maple (Acer rubrum L.), historically a common but not abundant tree species in North America, has increased in abundance throughout its range over the last several decades; however, it has received little attention in growth and yield studies. The objectives of this study were to (i) evaluate the effects of stocking level and stand density on o...

The use of ecological forestry to achieve management objectives, such as the maintenance of native biodiversity, has become increasingly common on public and private ownerships in North America. These approaches generally use natural disturbance processes and their structural and compositional outcomes as models for designing silvicultural prescrip...