Brice B. Hanberry

• Research Ecologist at US Forest Service

One question about historical grassland ecosystems in the Great Plains region of central North America is the percentage of tree cover overall and near major rivers, compared to current tree cover. Here, I assessed tree cover in reconstructions of historical grasslands in the eastern Great Plains, isolating tree cover adjacent to major rivers, and...

Pollinator species have declined globally during the last several decades due to a variety of factors, including habitat destruction and degradation, pesticides, disease and climate change. To examine the effects of climate change on pollinator distributions, I modelled summer occurrences of pollinator species from North America under current clima...

The relative influence of climate and Indigenous cultural burning on past forest composition in southern New England, US, remains debated. Employing varied analyses, this study compared data on Indigenous settlements from over 5000 years before present (YBP) with relative tree abundances estimated from pollen and land survey records. Results sugges...

Hanberry, Brice; Reeves, Matt C.; Brischke, Andrew; Hannemann, Mike; Hudson, Tipton; Mayberry, Richard; Ojima, Dennis; Prendeville, Holly R.; Rangwala, Imtiaz. 2019. Managing Effects of Drought in the Great Plains. In: Vose, James M.; Peterson, David L.; Luce, Charles H.; Patel-Weynand, Toral, eds. Effects of drought on forests and rangelands in th...

Data-driven decision support can help guide sustainable grazing management by providing an accurate estimate of grazing capacity, in coproduction with managers. Here, we described the development of a decision support model to estimate grazing capacity and illustrated its application on two sites in the western United States. For the Montgomery Pas...

In water‐limited dryland ecosystems of the Western United States, climate change is intensifying the impacts of heat, drought, and wildfire. Disturbances often lead to increased abundance of invasive species, in part, because dryland restoration and rehabilitation are inhibited by limited moisture and infrequent plant recruitment events. Informatio...

Since Euro-American settlement and associated fire exclusion, grasslands and open forests have converted to forests throughout the United States. Contributing to the weight of evidence, we determined if forestation also occurred in forests and grasslands of Colorado. Our study extent encompassed landscapes of the 0.5 million ha Arapaho and Roosevel...

Applying an interaction framework, we examined whether climate change and combined land use and disturbance changes were synergistic, antagonistic, or neutral for forest issues of wildfires, tree growth, tree species distributions, species invasions and outbreaks, and deer herbivory, focused on the eastern United States generally since the 1800s an...

The southeastern United States was historically characterized by open forests featuring fire-adapted species before land-use change. We compared tree composition and densities of historical tree surveys (1802 to 1841) to contemporary tree surveys, with the application of a similarity metric, in the Coastal Plain ecological province of Mississippi,...

Globally, in remaining wildlands, tree densities and forested cover have increased in grasslands and open forests since European settlement. In the southern Rocky Mountains of Colorado, United States, we determined tree composition and tree cover from historical (years 1875 to 1896) surveys and compared them to current (2002 to 2011) tree compositi...

Hanberry, Brice; Zheng, Xing; Johnson, Erik; Furniss, Michael J. 2024. Infrastructure, flood risk, and sustainable operations in Front Range national forests (Chapter 10). In: Hanberry, Brice B., ed. Colorado Front Range climate change vulnerability assessment for National Forests. Gen. Tech. Rep. RMRS-GTR-438. Fort Collins, CO: U.S. Department of...

Hanberry, Brice; Timberlake, Thomas; Clark, Nehalem; Miller, Brian W.; Peterson, Courtney. 2024. Scope, setting, and purpose of the Colorado Front Range climate change vulnerability assessment for national forests (Chapter 1). In: Hanberry, Brice B., ed. Colorado Front Range climate change vulnerability assessment for National Forests. Gen. Tech. R...

Hanberry, Brice. 2024. Summarizing concerns for natural resources due to climate change and interactions with non-climate stressors in the Rocky Mountains (Chapter 2). In: Hanberry, Brice B., ed. Colorado Front Range climate change vulnerability assessment for National Forests. Gen. Tech. Rep. RMRS-GTR-438. Fort Collins, CO: U.S. Department of Agri...

Karau, Eva; Hanberry, Brice; Dillon, Greg. 2024. Fire risk and climate change in the Colorado Front Range (Chapter 9). In: Hanberry, Brice B., ed. Colorado Front Range climate change vulnerability assessment for National Forests. Gen. Tech. Rep. RMRS-GTR-438. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research...

Species distribution models contain bias, or inaccurate predictions, due to predictors and species occurrences. Collinearity of predictor variables is a concern limited to standard error of estimates for data models, although issues remain about identification of important variables and model transferability, whereas thinning of species occurrences...

Researchers have debated the relative importance of environmental versus Indigenous effects on past fire regimes in eastern North America. Tree-ring fire-scar records (FSRs) provide local-resolution physical evidence of past fire, but few studies have spatially correlated fire frequency from FSRs with environmental and anthropogenic variables. No s...

Erosion is a concern due to environmental degradation, loss of valuable cropland, increased sediment loads in aquatic systems, and reduced reservoir capacity. To manage erosion, riparian forest buffers and bendway weirs were installed in the Little Blue River, Kansas, during years 2002–2010. To illustrate land cover changes associated with manageme...

While many tree species occur across the Coastal Plain of the southeastern United States, longleaf pine (Pinus palustris C. Lawson) savannas and woodlands once dominated this region. To quantify longleaf pine’s past primacy and trends in the Coastal Plain, we combined seven studies consisting of 255,000 trees from land surveys, conducted between 18...

Climate classifications supply climate visualization with inference about general vegetation types. The Köppen classification system of thermal classes and an arid class is widely used, but options are available to strengthen climate change detection. For this study, I incorporated temperature and aridity information into all climate classes to iso...

Present-day species distributions modeled with climate variables cannot provide potential future climate space for species that have contracted in range due to extirpations, regardless of abundant sample sizes within current ranges. My objective was to examine effects of range contractions on modeling of species to determine suitable space under cl...

Using Fire Compartments and Historical Land Cover to Rediscover Grasslands in the Eastern U.S. for Restoration & Management https://www.youtube.com/watch?v=IFglDFeiAz0

Background One issue in invasive plant ecology is identification of the factors related to the invasion process that increase number of non-native species. When invasion by non-native species increases, so does the probability that some non-native species will become harmful, or classified as invasive species, which disrupt natural ecosystems with...

Land area in urban use may be growing faster than population growth, increasing urban sprawl. With calibrated population density thresholds from the Worldpop population model, area and densities can be measured for suburban and urban density classes (≥ 250 humans per square kilometer) at global and national scales and both broad multi-city agglomer...

Pollen reconstructions of tree genera in North America since glaciation are available, but species distributions predicted for paleoclimate based on tree inventories may inform knowledge gaps. Here I examined the distributions of 25 species or species groups from 20 000 years ago (ka) to 5 ka to give potential paleoecological ranges of boreal and t...

Natural disturbances are critical ecosystem processes, with both ecological and socioeconomic benefits and disadvantages. Large herbivores are natural disturbances that have removed plant biomass for millions of years, although herbivore influence likely has declined during the past thousands of years corresponding with extinctions and declines in...

Environmental factors control species distributions and abundances, but effectiveness of land use and disturbance variables for modeling species generally is unknown compared to climate, soil, and topography variables. Therefore, I used predictor variables from categories of 1) land use and disturbance, 2) climate, and 3) soil, topography, and wind...

Ecosystem transformations to altered or novel ecological states are accelerating across the globe. Indicators of ecological resilience to disturbance and resistance to invasion can aid in assessing risks and prioritizing areas for conservation and restoration. The sagebrush biome encompasses parts of 11 western states and is experiencing rapid tran...

Background Maximizing the effectiveness of fuel treatments at landscape scales is a key research and management need given the inability to treat all areas at risk from wildfire. We synthesized information from case studies that documented the influence of fuel treatments on wildfire events. We used a systematic review to identify relevant case stu...

Background: Past burning by Native Americans can be analyzed from tree-ring fire-scar records (FSRs) via dendrochronological methods. However, the degree to which FSRs have adequately captured the varied locations where Native Americans burned landscapes, at both local and regional scales, remains largely unknown. Also unassessed is whether individ...

In drylands, water‐limited regions that cover ~40% of the global land surface, ecosystems are primarily controlled by access to soil moisture and exposure to simultaneously hot and dry conditions. Quantifying ecologically relevant environmental metrics is difficult in drylands because the response of vegetation to moisture and temperature condition...

Wildfires, tree removals, and deer herbivory are potential pathways for spread of non-native plants. I modeled the number of recorded nonnative plant species by county compared to wildfire area, tree removals, and deer densities in the eastern United States and also eastern forests. Species richness of 1016 plant species in 780 primarily forested c...

No common global definition exists of urban populations, resulting in a lack of shared standards across countries for equivalent comparisons. Therefore, I used global population models of Landscan, Worldpop, and Gridded Population of the World to generate a provisional classification of population density classes to define urban and rural by human...

Tree distributions and densities have been dynamic since Euro-American settlement in North America. Historically dominant fire-tolerant tree species have decreased, and fire-sensitive, successional species have increased, and tree species have expended westward since the 1800s into the central Great Plains grasslands. Divergent compositional trajec...

Climate classification allows an efficient encapsulation of climate data into climate units. For North America and most of Central America during 20, 14, 13, 11, 10, 7, 5, and 1 thousand years ago (ka) and recent years, I applied a Köppen-Trewartha classification system, but with dry classes subsumed under primary thermal classes to preserve inform...

Old-growth open forests of foundation longleaf and shortleaf pine savannas and woodlands have been replaced by successional closed forests and pine plantations in the southeastern United States

A tour of the central eastern historical forests, which primarily were oak, with some beech and pine locations.

Historically, grasslands with limited tree presence were embedded in a matrix of predominantly open oak and pine forests in the eastern United States. These open ecosystems mostly have been lost to other land uses, particularly agriculture, and also to closed forests under fire exclusion because frequent surface fire prevents tree encroachment. We...

Climate and vegetation phenology are closely linked, and climate change is already impacting phenology in many systems. These impacts are expected to progress in the future. We sought to forecast future shifts in rangeland growing season timing due to climate change, and interpret their importance for land management and ecosystem function. We trai...

We used historical and contemporary survey data to assess the dynamics in two old-growth forests at Savage Mountain, Maryland, versus secondary forests from the surrounding landscape of the northern Allegheny Mountain Plateau (AMP). This is the first published compilation of witness trees from western Maryland. The old-growth forests on Savage Moun...

Heat waves lasting days or weeks are among potential hazards expected to increase with climate change, but beyond heat waves, sustained temperatures may be incompatible with high urban population densities. I examined patterns of population density classes and exposure to maximum monthly temperature to identify where high urban population density c...

Increased abundance of historically rare native tree species is symptomatic of land use change that causes ecosystem regime shifts. I tested for an association between mean agricultural area, a proxy for land use change, and native tree species. I first modeled agricultural area during years 1850 to 1997 and historical and current percent compositi...

Eastern redcedar (Juniperus virginiana L.) is increasing in density in the eastern United States and expanding in range to the west, while western Juniperus species also are increasing and expanding, creating the potential for a novel assemblage. I estimated range expansion and intersection by comparing recent USDA Forest Service Forest Inventory a...

Forests in the western United States generally have increased in tree density since Euro-American settlement, particularly through increases in fire-sensitive species, such as spruces, firs, and junipers. Like most areas, the Black Hills region in western South Dakota and eastern Wyoming was logged for forest products and underwent agricultural con...

Land use by Indigenous people (Native Americans) and climate are primary factors affecting the dynamics of oak (Quercus) forests and woodlands in the eastern United States. Prior to Euro-American settlement, much of the eastern deciduous forest was dominated by oak species. The role of periodic surface burning, agriculture, and other forms of land...

Maximizing the effectiveness of fuel treatments at the landscape scale is a key research and management need given the inability to treat all areas at risk from wildfire, and there is a growing body of scientific literature assessing this need. We synthesized existing scientific literature on landscape-scale fuel treatment effectiveness in North Am...

Long-term observations inform relationships among changes in vegetation, climate, and land use. For the eastern United States, I compared the timing of tree change, comprised of density and diversity increases, with the timing of climate change, as measured by change point detection of the Palmer Modified Drought Index (PMDI) that accounts for wate...

Nowadays forest fires are so rare in the Mississippi Alluvial Valley and other floodplains of the southeastern USA that these floodplains appear fireproof. Fire was once much more common across the Southeastern Coastal Plain, including in these forested floodplains. Even so, fire was not the fundamental ecological disturbance in floodplain forests...

White‐tailed deer (Odocoileus virginianus) populations have recovered to about 30 million animals in the United States, but land cover has changed during the interval of recovery. To address the relationship between deer densities and current land cover at regional scales, I applied random forests and extreme gradient boosting classifiers to model...

Land use and fire exclusion have influenced ecosystems worldwide, resulting in alternative ecosystem states. Here, I provide two examples from the southeastern United States of fire-dependent open pine and pine-oak forest loss and examine dynamics of the replacement forests, given continued long-term declines in foundation longleaf (Pinus palustris...

Climate may separate grasslands from surrounding forests and shrublands, but an alternative option is that grasslands are suitable for trees except in the presence of frequent fires, which are spread great distances by strong winds. To develop a ruleset that demarcated the central North American grasslands, I modeled grasslands using precipitation...

Open forests of savanna and woodlands span the spectrum between closed canopy forests and treeless grasslands, and therefore contain structure, composition, and function distinctive from either endpoint. In this special issue, researchers provide examples from different open forest ecosystems to examine the underlying ecological principles and spec...

Forest classifications by disturbance permit designation of multiple types of both old growth forests and shorter-lived forests, which auto-replace under severe disturbance, and also identification of loss of the disturbance type and associated forest. Historically, fire and flooding disturbance regimes, or conversely, infrequent disturbance, produ...

Open forests: Structure, composition, function, and management

We discovered unique Douglas-fir open woodlands in the Umatilla National Forest using historical surveys. Historical ponderosa pine forests of the western United States are transitioning to denser forests comprised of a greater proportion of fire-sensitive species, including true firs. We used historical (1879 to 1887) surveys to quantify the compo...

TWS 2020 presentation

Fire-sustained open oak and pine forests were once widespread across eastern North America, but are now comparatively scarce. To regain the goods and services of these open forests, managers are increasingly looking to restore them with the silvicultural systems and tools best suited to meet their objectives. Hence, we synthesized a number of resea...

Fire is an ecological process that also has socioeconomic effects. To learn more about fire occurrence, I examined relationships between land classes and about 12,000 spatially delineated large wildfires (defined here as uncontrolled fires ≥200 ha, although definitions vary) during 1999 to 2017 in the conterminous United States. Using random forest...

Recent global declines of pollinator populations have highlighted the importance of pollinators, which are undervalued despite essential contributions to ecosystem services. To identify critical knowledge gaps about pollinators, we describe the state of knowledge about responses of pollinators and their foraging and nesting resources to historical...

Once dominant but now largely excluded from eastern North America, open forests of savannas to woodlands occupy the ecosystem gradient between grasslands and closed forests. These fire-maintained systems differ in structure, processes, and species from closed canopy, succession-driven forests that currently dominate this region. In functional open...

On the Ground •Remote sensing for rapid estimation of forage losses. •Cross referencing forage losses from drought with ecological sites can aid seeding decisions. •Drought monitors, by themselves, do not necessarily reflect extent and scope of forage losses. •Partnering with multiple agencies and stakeholders can enhance the overall response to d...

Despite widespread interest in white‐tailed deer ( Odocoileus virginianus ) in the southeastern United States, historical deer populations and densities have not been compiled into one accessible source. We digitized maps from 1950, 1970, 1982, and 2003 and reviewed literature to quantify population sizes and densities in the Southeast, although pr...

Pre-Euro-American settlement vegetation provides information about historical ecology. I evaluated baseline conditions and novel status of current forests in Michigan using historical (1836 to 1858) and current (2010–2015) surveys and assessed quantitative and qualitative measures of novel status. Aspen (increased from 2% to 11% of all trees) and r...

The wildland–urban interface (WUI) occurs at the intersection of houses and undeveloped wildlands, where fire is a safety concern for communities, motivating investment in planning, protection, and risk mitigation. Because there is no operational definition of WUI based on where fires in fact have occurred, I used fire occurrences to objectively es...

Energy is an integral part of society. The major US energy sources of fossil fuels (coal, oil, natural gas); biofuels (ethanol); and wind are concentrated in grassland ecosystems of the Great Plains. As energy demand continues to increase, mounting pressures will be placed on North American grassland systems. In this review, we present the ecologic...

Historically open oak and pine savannas and woodlands have transitioned to closed forests comprised of increased numbers of tree species throughout the eastern United States. We reviewed evidence for and against a suite of previously postulated drivers of forest transition focused on (1) change in fire regimes, (2) increased precipitation, (3) incr...

Climate change is increasing the risk of extreme events, resulting in social and economic challenges. I examined recent past (1971–2000), current and near future (2010–2039), and future (2040–2069) fire and heat hazard combined with population growth by different regions and residential densities (i.e., exurban low and high densities, suburban, and...

Throughout the Great Plains, aboveground annual net primary productivity (ANPP) is a critical ecosystem service supporting billions of dollars of commerce and countless stakeholders. Managers and producers struggle with high interannual change in ANPP, which often varies 40% between years due to fluctuating precipitation and drought. To quantify AN...

Background Despite availability of valuable ecological data in published thematic maps, manual methods to transfer published maps to a more accessible digital format are time-intensive. Application of object-based image analysis makes digitization faster. Methods Using object-based image analysis followed by random forests classification, we rapid...

Historical forests (circa 1799 to 1846) of Indiana were predominantly composed of American beech (25% of all trees) and upland oaks (27% of all trees). I compared historical forest composition, using studies of smaller areas to approximate composition for uncommon species or genera (< 4.5% of all trees) and forest types, to current forest compositi...

White-tailed deer (Odocoileus virginianus) have increased during the past century in the USA. Greater deer densities may reduce tree regeneration, leading to forests that are understocked, where growing space is not filled completely by trees. Despite deer pressure, a major transition in eastern forests has resulted in increased tree densities. To...

Abstract Background Current forests of the eastern USA have the potential to succeed in composition to more shade-tolerant species. However, long-term processes of transition from fire-tolerant tree species to fire-sensitive species and effects of current land use on forests may interfere with successional progression. Methods I examined if forests...

The Great Plains Grassland Summit: Challenges and Opportunities from North to South was held April 10–11, 2018 in Denver, Colorado to provide syntheses of information about key grassland topics of interest in the Great Plains; networking and learning channels for managers, researchers, and stakeholders; and working sessions for sharing ideas about...

In Wisconsin, as in other states, management goals sometimes include restoration of historical forest conditions, which may prepare forests to be more compatible with future climates, disturbances such as drought and fire, and forest health threats. We quantified historical (1830–1866) composition and structure to develop historical reference condi...

Methods to extract data from figures

The Great Plains is the grasslands of the central United States, but precise delineation of this region has evaded agreement due to the transition between Great Plains grasslands and forests of the eastern United States. After comparing Great Plains delineations in readily available geographic information system layers, I established a northeastern...

Many potential geographic information system (GIS) applications remain unrealized or not yet extended to diverse spatial and temporal scales due to the relative recency of conversion from paper maps to digitized images. Here, we applied GIS to visualize changes in the ecological boundaries of plant hardiness zones and the Köppen-Trewartha classific...

Wildlife biologists classify some bird species as early successional because of apparent dependence on early successional vegetation such as forbs, grasses, shrubs, and small trees. We propose that many “early successional” species were more often associated with open forests such as savannas and woodlands, which covered a much greater extent of th...

We present a reconceptualization of forests in eastern North America by differentiating the ecological characteristics of open oak (Quercus) and pine (Pinus) forests from closed successional and old‐growth forests. Despite historical abundance of savannas and woodlands, the fundamental ecology of open forest ecosystems remains ill‐defined when comp...

We address the climate versus disturbance debate to understand drivers of change in human-environment systems. We examine whether recent increased precipitation episodes (‘pluvials’) are unique and have ecological implications for the humid climate of the eastern United States. Robust statistical analyzes presented here indicate that the 20th centu...

Forests and grasslands have changed during the past 200 years in the eastern USA, and it is now possible to quantify loss and conversion of vegetation cover at regional scales. We quantified historical (ca. 1786–1908) and current land cover and determined long-term ecosystem change to either land use or closed forests in eight states of the Great L...

Historical forests in the Southeastern Mixed Forest province of the United States have been less researched than other regions using historical tree surveys. We used 81,000 tree records from surveys during the 1800s to quantify composition of this ecological province. Upland oaks and pines comprised about 75% of all trees, with relatively equal com...

Historical GIS involves applying GIS to historical research. Using a unique method, I recovered historical tree survey information stored in bar chart figures of a 1956 publication. I converted PDF files to TIF files, which is a format for a GIS layer. I then employed GIS tools to measure lengths of each bar in the TIF file and used a regression (...

Original bar graph from Potzger, Potzger & McCormick (1956) as a TIF GIS layer

Longleaf pine (Pinus palustris) historically was a widespread ecosystem composed of a simple tree canopy and grasslands ground layer. After widespread loss of this ecosystem due to logging and fire exclusion, little quantitative information exists about historical structure for restoration goals. We identified composition in De Soto National Forest...

Context Species distribution models (SDM) establish statistical relationships between the current distribution of species and key attributes whereas process-based models simulate ecosystem and tree species dynamics based on representations of physical and biological processes. TreeAtlas, which uses DISTRIB SDM, and Linkages and LANDIS PRO, process-...

Context Global climate change impacts forest growth and methods of modeling those impacts at the landscape scale are needed to forecast future forest species composition change and abundance. Changes in forest landscapes will affect ecosystem processes and services such as succession and disturbance, wildlife habitat, and production of forest produ...