Michael R. Saunders

Purdue University | Purdue · Department of Forestry and Natural Resources

Managing old-growth forests and promoting old-growth complexity in aging forests for carbon emissions mitigation has become an important component of diversified land management strategies. In the midwestern US, the Central Hardwoods Region (CHR) is the largest continuous deciduous forested area and includes a diverse range of species compositions,...

The advantages of clonal forestry have been well described, but little progress has been made in the identification of phenotypes best suited to this method in high-value hardwood species. The genetic variation within, clonal repeatability (broad-sense heritability) of, and Pearson's correlations among phenological, morphological, physiological, an...

Forests provide myriad ecosystem services, many of which are vital to local and regional economies. Consequently, there is a need to better understand how predicted changes in climate will impact forest dynamics and the implications of such changes for society as a whole. Here we focus on the impacts of climate change on Indiana forests, which are...

The seed and seed oil of Xanthoceras sorbifolium Bunge has high value in multiple applications, but varies considerably in different populations. To provide a basis for seed selection, physicochemical traits of the seeds from 13 areas were determined and analyzed in relation to geographical-climatic factors. Most mineral elements and fatty acids ex...

The iconic American chestnut (Castanea dentata) once spanned a large portion of eastern North America before its functional extinction in the early 20th century due primarily to non-native fungal pathogens. The pronounced loss of this species likely resulted in an abrupt alteration of many ecological processes , including fire. The potential to res...

Loss of native foundation tree species to introduced pests profoundly alters the structure and function of many forest ecosystems. Recent advances to resurrect or prevent the loss of species by developing resistant hybrids hold promise, but uncertainty remains about the potential impacts of introducing a novel genotype on ecological processes, such...

In eastern North America, oak (Quercus) regeneration failure has spurred management using silvicultural approaches better aligned with the autecology of oaks. In particular, shelterwood harvests can create favorable intermediate light conditions for oak establishment and prescribed fire is predicted (by the oak–fire hypothesis) to favor oak regener...

Securing desirable regeneration is essential to sustainable forest management, yet failures are common. Detailed seedling measurements from a forest inventory across 24 northern US states were examined for plausible regeneration outcomes following overstory removal. The examination included two fundamental regeneration objectives: 1) stand replacem...

Despite their long history as a forest dominant, the importance of Quercus (oak) species is declining under contemporary disturbance regimes in many parts of the world. This is cause for concern considering the great economic and ecological value of this genus. While many chronosequence studies have shown that clearcutting has accelerated the loss...

Throughout eastern North America, oaks (Quercus) are a foundational tree species, but are regenerating poorly, particularly on mesic sites. This regeneration failure has spurred development of new management practices that create heterogeneous regeneration conditions that better match oak's response to disturbances such as surface fire and windthro...

Invasive shrubs in forest understories threaten biodiversity and forest regeneration in the eastern United States. Controlling these extensive monotypic shrub thickets is a protracted process that slows the restoration of degraded forest land. Invasive shrub removal can be accelerated by using forestry mulching heads, but evidence from the western...

Establishing adequate advanced oak reproduction prior to final overstory removal is crucial for regenerating oak forests in the eastern U.S. Many management approaches exist to this end, but benefits associated with any individual technique can depend on the suite of techniques employed and the geographic location. At four mixed-hardwood upland for...

Declines in the diversity of herbaceous and woody plant species in the understory of eastern North American hardwood forests are increasingly common. Forest managers are tasked with maintaining and/or promoting species diversity and resilience; however, the success of these efforts depends on a robust understanding of past and future system dynamic...

Declining populations of forest songbirds in the eastern U.S. have emphasized a need for scientists and managers to understand habitat selection by birds in remnant patches of contiguous forest. Past work has identified effects of landscape-scale covariates on bird occurrence and abundance; however, less is known about the effects of local-scale fo...

Securing desirable forest regeneration outcomes is an essential component of sustainable forest management. When natural reproduction is preferred over planting, achieving desirable outcomes may be the principal challenge for forest managers, as reports of struggles and even failures are common across many regions and forest ecosystems. Informing m...

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...

In this inquiry-based unit, students use real scientific data to investigate how a bird community and individual forest animals respond to a clearcut timber harvest. In this investigation, students: use scientific inquiry to gain knowledge and answer questions; apply that knowledge to the engineering design process; and design a viable management s...

Gap- or group-based silvicultural techniques can influence understory conditions and regeneration in the forest matrix beyond harvest boundaries, however this regeneration is frequently overlooked. We present early data from the first large-scale expanding group shelterwood (Femelschlag) harvests in the Central Hardwood Region, focusing on spatial...

Biomass harvesting removes unmarketable vegetative material from timber harvests for use as cellulosic bioenergy, leaving only leaf litter. To test whether biomass harvests negatively affect red-backed salamander (Plethodon cinereus) populations, we set up coverboard arrays at 10 sites (mean 3.29 ha, range 2.35-4.61 ha) with varying degrees of biom...

Underplanting tree seedlings in areas where natural regeneration is limited may offer a tool by which desired overstory composition can be maintained or restored in forests. However, invasive plant species and ungulate browsing may limit the effectiveness of underplanting, and in-turn, the successful restoration of forest ecosystems. Individually,...

Contemporary forest management offers a trade-off between the potential positive effects of habitat heterogeneity on biodiversity, and the potential harm to mature-forest communities caused by habitat loss and perforation of the forest canopy. While the response of taxonomic diversity to forest management has received a great deal of scrutiny, the...

Aboveground tree growth is influenced by light availability, light capture, and the efficiency captured light is converted into growth. All three factors are influenced by neighborhood species composition and stand structure and can be modified with silvicultural treatments. The objective was to examine the absorption of photosynthetically active r...

Forest management and ungulate herbivory are extant drivers of herbaceous-layer community composition and diversity. We conducted a white-tailed deer (Odocoileus virginianus) exclosure experiment across a managed landscape to determine how deer impacts interact with the type of forest management system in influencing herb-layer (all vascular plants...

We resampled plots from a repeated measures study implemented on the Hoosier National Forest (HNF) in southern Indiana in 1988 to investigate the influence of site and seedling physical attributes on height growth and establishment success of oak species (Quercus spp.) reproduction in stands regenerated by the clearcut method. Before harvest, an ar...

Silvicultural strategies such as thinning may minimize productivity losses from a variety of forest disturbances, including forest insects. This study analyzed the 10-year postthinning response of stands and individual trees in thinned white spruce (Picea glauca [Moench] Voss) plantations in northern Minnesota, USA, with light to moderate defoliati...

We examined the effects of partial harvesting on the successional and structural development of forest stands relative to an unmanaged relict stand in Quercus-dominated forests in Indiana, USA over an 84-year period. Despite abundant ingrowth of shade-tolerant Acer and Ulmus species into the understorey of all stands, the double-harvest stand exhib...

Aims Using a network of permanent plots, we determined how multiple old-growth forests changed over an 18–19-year period at a state-wide scale. This examination of change allowed us to assess how the compositional and structural stability of each forest varied with site characteristics (topography, physiography and productivity) and stochastic dist...

While negative impacts of invasive species on native communities are well documented, less is known about how these communities respond to the removal of established populations of invasive species. With regard to invasive shrubs, studies examining native community response to removal at scales greater than experimental plots are lacking. We examin...

The expansion of populations of invasive species continues to compromise the ecological and economic integrity of our natural resources. The negative effects of invasive species on native biota are widely reported. However, less is known about how the duration (i.e., age of oldest invaders) and intensity (i.e., density and percent cover) of an inva...

When a tree dies, it continues to play an important ecological role within forests. Coarse woody debris (CWD), including standing deadwood (SDW) and downed deadwood (DDW), is an important functional component of forest ecosystems, particularly for many dispersal-limited saproxylic taxa and for metapopulation dynamics across landscapes. Processes, s...

American chestnut (Castanea dentata) has been killed or reduced to recurrent stump sprouts throughout its range following the importation of multiple pathogens in the 19th and early 20th centuries. Understanding what drives chestnut growth and survival would aid the development of appropriate silvicultural guidelines for restoring the species once...

Little is known about local patterns and rates of woody plant invasions, and even less is known about changes in spatial patterning and factors influencing structural characteristics of individuals as invasion phase progresses from establishment to saturation. We examined age distributions and spatial patterns of Amur honeysuckle (Lonicera maackii...

Partial canopy cover promotes regeneration of many ecologically and/or economically favoured tree species in temperate mesic forests. However, the specific effects of belowground resource competition from different canopy strata in these systems are poorly understood. This is particularly the case for American chestnut (Castanea dentata (Marsh.) Bo...

American chestnut restoration depends on a multitude of biological, administrative, and technological factors. Germplasm traditionally bred for resistance to the chestnut blight disease caused by the exotic pathogen Cryphonectria parasitica has been deployed on national forests in the Eastern and Southern Regions of the National Forest System (NFS)...

Numerous models are available in northeastern North America to estimate aboveground tree biomass, yet most have focused on trees ≥12.5 cm diameter, and these models are often poor predictors of small tree biomass (<12.5 cm diameter). Additionally, models available to estimate small tree biomass often lack independent evaluation with field data. We...

Maintenance of late-successional structures to enhance biodiversity and sequester carbon has been a major focus of forest research over the past two decades. Several long-term, disturbance-based silvicultural trials have been installed to try to balance the maintenance of complex forest conditions yet allow for economical extraction of timber. One...

Background/Question/Methods Concurrent disturbances can interact to affect the diversity and spatial structure of forest understory plant communities. Forest management and deer herbivory are two common disturbances that often occur concurrently. Plant communities in canopy gaps tend to be dominated by ruderals due to increased resource availabili...

Amur honeysuckle (Lonicera maackii) is an exotic shrub that has invaded many forests throughout the United States. Although effects on native plants and birds have been documented, little is known about the influence of Amur honeysuckle on small mammals. We examined the short-term effects of removing Amur honeysuckle and other exotic shrubs on the...

Leaf area index (LAI) affects forest-atmosphere fluxes and light interception rates and thus influences forest productivity. Early silvicultural treatments affect LAI partitioning among species of different shade tolerance in natural stands due to changes in composition and structure. We examined effects of species compositional objectives (conifer...

http://www.treesearch.fs.fed.us/pubs/46841 American chestnut [Castanea dentata Marsh. (Borkh.)] is an iconic species with important ecological and utilitarian values, but was decimated by the mid-20th century by exotic fungal species from Asia. Successful restoration will require sustainable silvicultural methods to maximize survival and afford ch...

Background/Question/Methods The Central Hardwood Region (CHR) was historically dominated by Quercus forests, woodlands, and savannas. Over the past century, changes in structure and species composition in CHR forests have been attributed to changes in the natural disturbance regime, with a pointed focus on reduced fire frequency. The primary objec...

Background/Question/Methods The ecosystem management paradigm embraces the restoration and maintenance of ecological processes across many scales, and coarse woody debris (CWD) is an essential element of forest ecosystems. Standing (SDW) and down dead wood (DDW) are important components whose many ecological roles are well documented, but our kno...

Epicormic branches can be a serious silvicultural problem in many Quercus species because of the potential reduction in log value associated with their occurrence. The phenomenon is also problematic for tree improvement since the genetic component of epicormic branching has not been well quantified. The strong influence of ontogeny on epicormic dev...

Intrastand variability is promoted by many silvicultural systems designed to emulate natural disturbance regimes (natural disturbance-based silviculture [NDBS] systems) in the eastern United States and Canada but this variability is difficult to model in many growth-and-yield models, limiting application by the region's forest managers. We used a r...

Early successional stands composed of naturally regenerated hardwood and conifer species are abundant in the forests of northeastern North America. Substantial improvements in the composition and growth of these stands may be possible with early management intervention. Unfortunately, stand responses to early management inputs are poorly understood...

Introduction Intensive plantation management of high value hardwoods, such as black walnut (Juglans nigra L.), is focused on maximizing both stem form and growth at the stand and tree level. While significant research has focused on genetic improvement in black walnut, little is known about the production ecology of this species in plantation setti...

Background/Question/Methods Amur honeysuckle (Lonicera maackii (Rupr.) Herder) is a non-native, invasive shrub that has aggressively colonized many forests in the central U.S. While it is well known that this species suppresses the growth and regeneration of native plants, less is known about factors influencing the spatial distribution and life s...

Public land management across North America now incorporates multiple ecological and social values and has led to use of increasingly complex silvicultural systems, such as those designed to emulate natural disturbance regimes, in an effort to manage for this wider variety of objectives. In the eastern United States and Canada, canopy gap-based sil...

In 2009, the Forest Inventory and Analysis Program (FIA) updated ts biomass estimation protocols by switching to the component ratio method to estimate biomass of medium and large trees. Additionally, FIA switched from using regional equations to the current FIA aboveground sapling biomass equations that predict woody sapling (2.5 to 12.4 cm d.b.h....

In 2009, the Forest Inventory and Analyss Program (FIA) updated ts bomass estmaton protocols by swtchng to the component rato method to estmate bomass of medum and large trees. Addtonally, FIA swtched from usng regonal equatons to the current FIA aboveground saplng bomass equatons that predct woody saplng (2.5 to 12.4 cm d.b.h.) bomass usng the Jen...

The formation of epicormic sprouts on the boles of trees is a phenomenon that has, until recently, been poorly understood. Renewed interest in the topic in the last two decades has led to significant advances in our knowledge of the subject, especially in regard to bud anatomy, morphology and ontogeny. There exists, however, no comprehensive synthe...

Background/Question/Methods Amur honeysuckle (Lonicera maackii (Rupr.) Herder) is a non-native shrub that was introduced to the United States from Asia in the 1890s. Since its introduction, it has aggressively colonized many forests throughout the central U.S., leading to decreased diversity and richness in native plant communities. We examined g...

Disturbance-based silvicultural systems generally seek to promote complex stand structures that are consistent with temporal and spatial patterns of natural disturbance while allowing for the sustainable harvest of timber. Gap-based harvesting systems are commonly used within this framework because they can be designed to approximate the frequencie...

Forest plantations in the northeastern United States comprise a small proportion of the total forest area. Most plantations are typically softwood dominated and managed for sawlog and pulpwood production, while high-yield hardwood plantations for bioenergy feedstocks have not been as widely investigated. The objective of this study was to compare t...

The effects of thinning treatments on growth and survivorship of white spruce (Picea glauca [Moench] Voss) plantations affected by recent eastern spruce budworm (SBW) outbreaks were examined over a 5-year period in northern Minnesota. Thinning treatments increased individual tree growth, live crown ratios (LCRs), and survival relative to unthinned...

We simulated growth and development from 481 plots within 21 even-aged, mixed hardwood stands (21-35 years old) under no treatment and crop tree release (CTR) treatments using the new Central States Variant of the US Forest Service Forest Vegetation Simulator. We assumed a multiobjective approach focused on financial returns (timber production) and...

Both nutrient concentrations and pre and post-harvest pool sizes were determined across down woody debris decay classes of several hardwood and softwood species in a long-term, natural disturbance based, silvicultural experiment in central Maine. Concentrations of N, P, Ca, Mg, Cu, Fe, and Zn generally increased 2- to 5-fold with increasing decay c...

The northeast variant of the Forest Vegetation Simulator (FVS-NE) produces output that is of considerable use to forest managers in the northeastern United States. Designed to be relatively easy to use and requiring modest data inputs, FVS-NE is readily available at no cost and is well documented. However, as with all models, users need to apprecia...

Height-diameter models were developed for nine tree species common to the northeastern United States: Abies balsamea, Acer rubrum, Betula papyrifera, B. populifolia, Picea rubens, P. mariana, Pinus strobus, Populus tremuloides, and Tsuga canadensis. Stem heights and diameters were collected from 6 146 trees (between 136 and 2 615 trees per species)...

Using inventory data from a long-term silviculture experiment in east-central Maine, spatial models were developed to analyze 28years (19742002) of stand structural dynamics. Differences in spatial pattern, species mingling, height differentiation, and relative stand complexity index (rSCI) were compared among five treatments: commercial clear-cutt...

Research plots in many long-term studies of forest ecosystems often cannot be used for spatial modeling because of their small scale and nested inventory design. This has been unfortunate as these plots represent some of the best records of structural development as affected by forest management. I developed methodologies to reconstruct both tree h...

The most comprehensive study of stand dynamics in the Acadian Forest Region is an experiment by the USDA Forest Service at the Penobscot Experimental Forest (PEF) in Maine. It was established from 1952-1957 to study changes in structure, composition, and productivity from an array of silvicultural treatments. Ingrowth, accretion, and mortality of i...

To investigate complex growth compensation patterns, white pine (Pinus strobus L.) seedlings were clipped to simulate different herbivory levels. Seedlings were growing with different understory competition levels (created through monthly weeding vs no brush control) under a range of overstory canopy closures. Compensation patterns varied for the d...

We measured the response of white pine (Pinus strobus L.) saplings after partial release of a hardwood overstoiy on three sites in central Minnesota. Both lieiglit and diameter growth increased quickly after release compared to prerelease growth. Diameter growth response was related to prerelease diameter growth, but not to initial size of the sapl...

Browsing of seedlings by white-tailed deer (Odocoileus virginianus) can make natural and artificial forest regeneration difficult. Few mathematical models predict deer browsing within and between sites, giving managers only landscape-level characteristics, such as deer population levels and yearly snowfall measurements, to determine where deer-prot...