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To enhance forest resilience to predicted increases in forest stressors, managers increasingly desire ecologically based restoration approaches that increase ecosystem adaptation potential. Mixedwood stands, which contain a range of life history and functional traits, may be more resistant and resilient to ecosystem stressors. Management of Quercus–Pinus mixedwood stands includes the use of prescribed fire, which requires an understanding of vegetation-fuels-fire feedbacks in these ecosystems. However, a paucity of knowledge exists on the intra-stand spatial patterns of fire effects. We analyzed the effects of a newly initiated prescribed fire program on the intra-stand characteristics of understory woody plants and fuelbed composition and loading in a long-unburned Quercus–Pinus mixedwood stand in Tennessee, USA. We sampled vegetation and fuels in two plots, one that experienced two prescribed fires (burned plot), and one fire-excluded plot directly adjacent (unburned plot). On the burned plot, we recorded lower sapling and seedling densities across taxa. Spatial analysis of advance reproduction in the burned plot indicated a combination of patchy fire effects, canopy openings, and high-light understory environments. We documented significant reductions in total fuel mass. The combination of spatial analysis and ordination revealed that prescribed fires homogenized fuel loads within the burned plot. [ABSTRACT FROM AUTHOR]

Temperate mixedwoods (hardwood-softwood mixtures) in central and eastern United States and Canada can be classified into two overarching categories: those with shade-tolerant softwoods maintained by light to moderate disturbances and those with shade-intolerant to mid-tolerant softwoods maintained by moderate to severe disturbances. The former includes red spruce (Picea rubens Sarg.), balsam fir (Abies balsamea (L.) Mill.), or eastern hemlock (Tsuga canadensis (L.) Carr.) in mixture with northern hardwood species; the latter includes pine (Pinus) --oak (Quercus) mixtures. Such forests have desirable socio-economic values, wildlife habitat potential, and (or) adaptive capacity, but management is challenging because one or more softwood species in each can be limited by depleted seed sources, narrow regeneration requirements, or poor competitive ability. Appropriate silvicultural systems vary among mixedwood compositions depending on shade tolerance and severity of disturbance associated with the limiting softwoods, site quality, and level of herbivory. Sustainability of mixedwood composition requires that stand structure and composition be managed at each entry to maintain vigorous trees of species with different growth rates and longevities and to encourage development of advance reproduction or seed-producing trees of desired species. Regardless of silvicultural system, maintaining seed sources of limiting softwoods, providing suitable germination substrates, and controlling competition are critical. Here, we describe commonalities among temperate mixedwoods in central and eastern North America and present a framework for managing them. Key words: mixed-species forests, deciduous-coniferous mixtures, silvicultural systems, tree regeneration, shade tolerance. Les forets mixtes (melanges de feuillus et de resineux) temperees du centre et de l'est des Etats-Unis et du Canada peuvent etre classees en deux categories principales : celles qui sont composees de resineux tolerants a l'ombre maintenus par des perturbations legeres a moderees et celles qui sont composees de resineux intolerants et semi-tolerants a l'ombre maintenus par des perturbations moderees a severes. La premiere categorie comprend l'epinette rouge (Picea rubens Sarg.), le sapin baumier (Abies balsamea (L.) Mill.) ou la pruche du Canada (Tsuga canadensis (L.) Carr.) en melange avec des especes de feuillus nordiques; la deuxieme categorie comprend des melanges de pins (Pinus) et de chenes (Quercus). Ces forets possedent une valeur socio-economique interessante, un potentiel d'habitat faunique ou une capacite d'adaptation, mais leur amenagement est difficile parce que la presence d'au moins une espece resineuse dans chaque categorie peut etre limitee par un manque de semences, des exigences de regeneration trop strictes ou une faible capacite concurrentielle. Les systemes sylvicoles qui sont appropries varient en fonction de la composition de ces forets et dependent de la tolerance a l'ombre et de l'intensite des perturbations associees aux resineux critiques, a la qualite de la station et au degre d'herbivorie. La durabilite de la composition des forets mixtes necessite que la structure et la composition des peuplements soient amenagees a chaque rotation de facon a maintenir des arbres vigoureux d'especes ayant des longevites et des taux de croissance differents et a favoriser le developpement de la regeneration preetablie ou d'arbres semenciers d'especes desirees. Quel que soit le systeme sylvicole, il est essentiel de maintenir des sources de semences des resineux critiques, de creer des substrats de germination appropries et de maitriser la concurrence. Dans cet article, nous decrivons les points communs entre les forets mixtes temperees du centre et de l'est de l'Amerique du Nord et presentons une marche a suivre pour leur amenagement. Mots-cles: forets mixtes, melanges de feuillus et de coniferes, systemes sylvicoles, regeneration des arbres, tolerance a l'ombre., Introduction Silviculture must integrate knowledge of forest ecology, growth and yield, and operations while accounting for multiple goals depending on the context of application (Puettmann et al. 2009). The design [...]

As interest in managing and maintaining mixedwood forests in the northern United States (US) grows, so does the importance of understanding their abundance and distribution. We analyzed Forest Inventory and Analysis data for insights into mixedwood forests spanning 24 northern US states from Maine south to Maryland and westward to Kansas and North Dakota. Mixedwoods, i.e., forests with both hardwoods and softwoods present but neither exceeding 75%-80% of composition, comprise more than 19 million hectares and more than onequarter of the northern US forest. They are most common in the Adirondack--New England, Laurentian, and Northeast ecological provinces but also occur elsewhere in hardwood-dominated ecological provinces. These mixtures are common even within forest types nominally categorized as either hardwood or softwood. The most common hardwoods within those mixtures were species of Quercus and Acer, and the most common softwoods were species of Pinus, Tsuga, and Juniperas. Although mixedwoods exhibited stability in total area during our analysis period, hardwood saplings were prominent, suggesting widespread potential for eventual shifts to hardwood dominance in the absence of disturbances that favor regeneration of the softwood component. Our analyses suggest that while most mixedwood plots remained mixedwoods, harvesting commonly shifts mixedwoods to either hardwood- or softwood-dominated cover types, but more specific information is needed to understand the causes of these shifts. Key words: hardwood, softwood, deciduous, coniferous, Forest Inventory and Analysis (FIA). Au fur et a mesure qu'augmente l'interet pour l'amenagement et le maintien des forets mixtes dans le nord des Etats-Unis, la comprehension de leur abondance et de leur repartition devient de plus en plus importante. Dans le but d'obtenir de l'information, nous avons analyse les donnees du programme d'inventaire forestier et d'analyse portant sur les forets mixtes de 24 Etats du nord des Utats-Unis, a partir du Maine vers le sud jusqu'au Maryland et vers l'ouest jusqu'au Kansas et au Dakota du Nord. Les forets mixtes, c'est-a-dire les forets composees a la fois de feuillus et de resineux, dont la proportion n'excede pas 75 a 80% dans un cas comme dans l'autre, representent plus de 19 millions d'hectares, ce qui correspond a plus du quart des forets du nord des Etats-Unis. Elles sont plus frequentes dans les provinces ecologiques des Adirondacks en Nouvelle-Angleterre, Laurentienne et du Nord-Est, mais elles sont aussi presentes ailleurs dans les provinces ecologiques dominees par les feuillus. Les forets mixtes sont courantes meme dans les types forestiers categorises nominalement comme etant feuillus ou resineux. Les feuillus les plus courants dans ces forets sont des especes des genres Quercus et Acer alors que les resineux les plus courants sont des especes des genres Pinus, Tsuga et Juniperus. Bien que la superficie totale des forets mixtes soit demeuree stable au cours de notre periode d'analyse, les gaules de feuillus etaient predominantes, ce qui indique que la composition d'une forte proportion de ces forets pourrait tendre vers une dominance des feuillus s'il n'y a pas de perturbations favorisant la regeneration de la composante resineuse. Nos analyses indiquent que meme si la plupart des parcelles de forets mixtes sont demeurees des forets mixtes, la recolte de bois modifie generalement la composition des forets mixtes vers des types de couvert domines par des feuillus ou des resineux, mais la comprehension des causes de ces changements necessite de l'information plus specifique. Mots-cles: feuillus, resineux, especes decidues, coniferes, programme d'inventaire forestier et d'analyse (FIA)., Introduction Forests with both hardwoods and softwoods (i.e., generally broadleaf, deciduous, and needle-leaf, evergreen trees, respectively) present but neither exceeding 75%-80% of basal area, crown cover, or other metric are [...]

Understanding the effects of fire on advance regeneration of oak (Quercus L.) species and their competitors is an important step in determining the role of prescribed fire in regenerating and restoring upland oak ecosystems. Our study aimed to understand how dormant-season prescribed fire affects advance regeneration of chinkapin oak (Quercus muehlenbergii Engelm.), black oak (Quercus velutina Lam.), and their major competitors at sites targeted for woodland restoration and management. We analyzed relationships between stem size and survival probability; determined the effect of fire temperature on survival probability; and compared how mortality, sprouting, and survival differed among species. For chinkapin oak, black oak, and bitternut hickory (Carya cordiformis (Wangenh.) K. Koch), mortality was low and rate of sprouting was high after shoot dieback. Initial basal diameter was significantly related to survival probability after one fire for all species except chinkapin oak and black oak. Height was a significant predictor of survival probability for all species except chinkapin oak. Although sugar maple (Acer saccharum Marsh.) also responded to fire by sprouting, it did so at a much lower rate than oaks and hickory (20% versus 43%-68%). These data reveal that heavily invaded, fire-suppressed woodlands on the prairie-forest border region may not experience major structural and compositional shifts without repeated burning or mechanical treatments. Key words: chinkapin oak, prescribed fire, mortality, logistic models. La comprehension des effets du feu sur la regeneration preetablie des especes de chene (Quercus L.) et de leurs concurrents est une etape importante pour determiner le role du brulage dirige dans la regeneration et la restauration des ecosystemes bien draines de chene. Notre etude visait a comprendre comment le brulage dirige applique pendant la saison de dormance influence la regeneration preetablie des chenes jaune (Quercus muehlenbergii Engelm.) et noir (Quercus velutina Lam.) et celle de leurs principaux concurrents sur des stations destinees a la restauration et l'amenagement de zones boisees. Nous avons analyse les relations entre la taille des tiges et la probabilite de survie, determine l'effet de la temperature du feu sur la probabilite de survie, et compare les differences de mortalite, de repousse et de survie entre les especes. Pour le chene jaune, le chene noir et le caryer cordiforme (Carya cordiformis (Wangenh.) K. Koch), la mortalite etait faible et le taux de repousse etait eleve apres la mort des tiges. Le diametre initial a la souche etait significativement lie a la probabilite de survie apres un feu pour toutes les especes sauf les chenes jaune et noir. La hauteur etait une variable predictive importante de la probabilite de survie de toutes les especes, a l'exception du chene jaune. Bien que l'erable a sucre (Acer saccharum Marsh.) ait aussi reagi au feu en produisant des repousses, le taux de repousse etait beaucoup plus faible que celui des chenes et du caryer (20 % contre 43 % a 68 %). Ces donnees revelent que les zones boisees fortement envahies et protegees du feu, et etablies dans l'ecotone entre la prairie et la foret peuvent se developper sans profonds changements structurel et compositionnel si des brulages diriges ou des traitements mecaniques ne sont pas appliques de facon repetee. [Traduit par la Redaction] Mots-cles: chene jaune, brulage dirige, mortalite, modeles logistiques., 1. Introduction Fire has been an important driver in shaping plant communities in the Central United States (US) for millennia (Abrams 1992; Anderson et al. 1999; Nelson 2010). As a [...]

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Richard Paul Guyette, an accomplished scientist and Emeritus Professor of Dendrochronology at the University of Missouri, passed away in 2023. Throughout his career, which spanned nearly 40 years, Guyette made significant contributions to tree-ring research, pioneering new methods and applications. His work included assessing climate change, dating historical structures, studying fire history, and analyzing dendrochemistry. Guyette's legacy continues to be relevant in addressing challenges facing forest ecosystems in North America, and he is recognized as an expert in dendrochronology and fire ecology. He is remembered for his passion, creativity, and influence in the field. [Extracted from the article]

Low-intensity surface fire is required to restore and maintain Quercus-Pinus mixedwood composition, structure, and function. However, historical fire exclusion has resulted in altered vegetation-fuel-fire feedbacks in long-unburned mixedwoods. Fire is now being reintroduced to reduce fire-intolerant understory and midstory stem density, consume excessive litter accumulation, eradicate the duff layer, and achieve various other goals; however, the consequences of restoring fire are poorly understood. The goal of this study was to quantify the effects of fire reintroduction on intra-stand Pinus echinata neighborhoods in a mixed Quercus-P. echinata stand following an extended period of fire exclusion. We report results from a 3-year sampling of the effects of one dormant season and one early growing season fire on woody plant dynamics, understory light, fuel conditions, and P. echinata basal duff-ring accumulation. The sapling assemblage was unaffected by one fire, but the second fire resulted in shoot mortality across all taxa. Understory light availability was unchanged after two fires, and litter depth was significantly reduced after the first and second fire. We found that fire seasonality was likely more important than fuel conditions to achieve desired fire effects. Our results indicated that continued fire and midstory treatment will be required to regenerate P. echinata. [ABSTRACT FROM AUTHOR]

The ground flora stratum affects stand structure, resource acquisition, nutrient cycling, and taxonomic richness in forest ecosystems. Disturbances such as thinning and prescribed fire alter forest understory growing conditions that generally increase ground flora cover and richness. We studied annual changes in ground flora assemblages over three growing seasons after fire in thinned and frequently burned (3-year rotation) Pinus-Quercus stands. Our results corroborated trends from other studies that indicated greater ground flora richness and cover after thinning and burning compared with thin-only treatments. We also found that the stratum experienced relatively rapid succession between growing seasons that complimented the tolerance succession model. Forbs had reduced cover and richness from increasingly difficult growing conditions over time and were replaced by woody plants, shrubs, and seedlings. This likely occurred from changing competition dynamics that favored quick growth in the first growing season and long-term investment in vertical growth in the third growing season. The successful regeneration pathways also fit ground flora regeneration models and added a unique pathway to strengthen the predictive power of these models. As many stand management goals are focused towards improving biodiversity, prescribed fire and thinning may be used to increase understory richness in Pinus-Quercus stands. Key words: ground flora, prescribed fire, herbs, litter, advanced reproduction. La strate composee de la flore du sol influence la structure du peuplement, l'acquisition des ressources, le recyclage des nutriments et la richesse taxonomique dans les ecosystemes forestiers. Les perturbations, telles que l'eclaircie et le brulage dirige, modifient les conditions de croissance dans le sous-bois des forets et augmentent generalement la richesse et le couvert de la flore du sol. Nous avons etudie les variations annuelles dans les assemblages de la flore du sol pendant trois saisons de croissance apres feu dans des peuplements eclaircis et frequemment brules (a tous les 3 ans) de pin et de chene (Pinus et Quercus, respectivement). Nos resultats corroborent les tendances rapportees dans d'autres etudes indiquant que la richesse et le couvert de la flore du sol augmentent apres une eclaircie et un brulage comparativement a une eclaircie seule. Nous avons egalement trouve que la strate connaissait une succession relativement rapide entre les saisons de croissance, ce qui va dans le sens du modele de succession base sur la tolerance. Le couvert et la richesse des plantes herbacees non graminoides ont diminue avec le temps a cause des conditions de croissance de plus en plus difficiles et elles etaient remplacees par des plantes ligneuses, des arbustes et des semis. Cela est survenu vraisemblablement a cause du changement dans la dynamique de la competition qui a favorise une croissance rapide durant la premiere saison de croissance et un investissement a long terme dans la croissance verticale durant la troisieme saison de croissance. Les trajectoires qui favorisent la regeneration correspondent aussi aux modeles de regeneration de la flore du sol et ont ajoute une trajectoire unique pour renforcer l'efficacite predictive de ces modeles. Etant donne que plusieurs objectifs d'amenagement des peuplements sont axes sur l'amelioration de la biodiversite, le brulage dirige et l'eclaircie pourraient etre utilises pour augmenter la richesse du sous-bois dans les peuplements de pin et de chene. [Traduit par la Redaction] Mots-cles: flore du sol, brulage dirige, herbacees, litiere, regeneration preetablie., 1. Introduction The ground flora stratum (herbaceous and woody plants [less than or equal to] 1 m from the forest floor) constitutes a majority of plant diversity and rare species [...]

Reference charts have long been used in the medical field for quantitative clinical assessment of juvenile development by plotting distribution quantiles for a selected attribute (e.g., height) against age for specified peer populations. We propose that early stand dynamics is an area of study that could benefit from the descriptions and analyses offered by similar references for various tree measures. Reference charts provide a flexible quantitative framework that would complement traditional methods for assessing tree development. In young, mixed stands, competitive dynamics are, in part, a function of intraspecific, interspecific, and temporal variation in height development. A suite of reference charts can explicitly describe each of these, offering additional context and potentially greater insight into the complex development patterns of young trees. We illustrate this possibility and potential applications by constructing height-age reference charts for several tree species in young, mixed stands within the Missouri Ozarks. Key words: height growth, percentile, regeneration, recruitment, stand dynamics. Des abaques de reference ont longtemps ete utilises dans le domaine medical pour realiser des evaluations cliniques quantitatives du developpement juvenile en tracant les quantiles de distribution d'un attribut selectionne (p. ex., la hauteur) en fonction de l'age pour des populations homologues specifiques. Nous croyons que la dynamique des jeunes peuplements est un domaine d'etude qui pourrait beneficier des descriptions et des analyses offertes par de tels outils de reference pour diverses mesures d'arbre. Les abaques de reference offrent un cadre quantitatif flexible qui completerait les methodes traditionnelles d'evaluation du developpement des arbres. Dans les jeunes peuplements mixtes, la dynamique de competition est partiellement fonction des variations intraspecifique, interspecifique et temporelle du developpement en hauteur. Une serie d'abaques de reference peut decrire explicitement chacune de ces relations, ce qui offre un contexte supplementaire et un apercu potentiellement meilleur des schemas complexes du developpement des jeunes arbres. Nous illustrons cette possibilite et des applications potentielles par la mise au point d'abaques de reference entre la hauteur et l'age de plusieurs especes d'arbres se developpant dans de jeunes peuplements mixtes situes dans les monts Ozarks au Missouri. [Traduit par la Redaction] Mots-cles: croissance en hauteur, percentile, regeneration, recrutement, dynamique des peuplements., Introduction The development of forest stands following disturbance includes general stages described through the study of stand dynamics. The early stages of this process are complex and dynamic, including the [...]

Mixed-species forests are, or were, a common feature of most forested regions around the globe (Bauhus et al. 2017b). The ecology and silviculture of these systems has been a consistent [...]

Successful canopy recruitment is one of the most important components of sustainable forestry practices. For many desirable species in oak-dominated forests, insufficient sapling growth is a common limitation to successful recruitment. The objectives of this study were to (i) examine the impact of overstory density on sapling growth in the Missouri Ozarks, (ii) investigate the potential for overstory retention to promote compositional shifts via interspecific differences in sapling height growth, and (iii) compare the use of mean and near-maximum growth rates to quantify the impact of overstory density on sapling growth and height differentiation among species. We found that the periodic annual height increment of saplings decreased with increasing overstory density for all species groups in this study (red oaks (Quercus spp.), white oaks (Quercus spp.), hickories (Carya spp.), sassafras (Sassafras spp.), blackgum (Nyssa spp.), dogwood (Cornus spp.), red maple (Acer spp.), ashes (Fraxinus spp.), and elms (Ulmus spp.)). There was evidence of interspecific differentiation in growth rates during the sapling stage, and the observed differences were more pronounced at low overstory densities. Increasing overstory densities either reduced or eliminated the differences in growth among species. Although red oaks displayed the greatest maximum growth rates of all species under low overstory densities ( Key words: silviculture, regeneration, recruitment, differentiation, quantile. Resume: Le succes du recrutement dans le couvert dominant est une des plus importantes composantes des pratiques de foresterie durable. Dans le cas de plusieurs especes desirees des forets dominees par le chene, la croissance insuffisante des gaules est le facteur qui limite couramment la reussite du recrutement. Les objectifs de cette etude consistaient a (i) examiner l'impact de la densite du couvert dominant sur la croissance des gaules dans les monts Ozarks du Missouri, (ii) evaluer le potentiel de mesures de retention du couvert dominant pour favoriser des changements de composition induits par des differences interspecifiques de croissance en hauteur des gaules et (iii) comparer l'utilisation des taux de croissance moyen et pres du maximum pour quantifier l'impact de la densite du couvert dominant sur la croissance des gaules et sur les differences de croissance entre les especes. Nous avons trouve que l'accroissement annuel periodique en hauteur des gaules diminuait avec l'augmentation de la densite du couvert dominant pour tous les groupes d'especes dans cette etude (chenes rouge et blanc, caryers, sassafras, nyssa, cornouiller, erable rouge, frenes et ormes). Il y avait des signes de differences interspecifiques du taux de croissance des gaules et les differences observees etaient plus prononcees lorsque la densite du couvert dominant etait faible. L'augmentation de la densite du couvert dominant reduisait ou eliminait les differences de croissance entre les especes. Bien que le chene rouge ait montre le taux maximal de croissance le plus eleve parmi toutes les especes lorsque la densite du couvert dominant etait faible ( Mots-cles: sylviculture, regeneration, recrutement, differentiation, quantile., Introduction Regeneration and canopy recruitment are two vital ecosystem processes necessary for sustainable forestry (Dey 2014). Unfortunately, difficulties and failures to regenerate either economically or ecologically important species are common [...]

This study aimed to investigate the effect of road construction on plant species composition, and tree and shrub regeneration in relation to soil properties. Ten transects were established perpendicular to the main axis of the road that went up to 35 m inside the forest. The sampling was done at plots located at 5, 15, 25, and 35 m along each transect. The relevé method of Braun--Blanquet was used for vegetation sampling. A total of 40 relevés were established, with each relevé covering an area of 100 m² (10 m x 10 m), to count the number of woody species regeneration. To study the physical and chemical properties of soils, composite soil samples were collected from the depth of 0-10 cm from three cores taken near the center of each plot. Results showed that plant species were classified into two groups using two-way indicator species analysis. Multivariate analyses (principal component analysis and canonical correspondence analysis) were used to identify the most important soil variables and determine relationships between plant species composition and soil properties. Classification of vegetation into two recognizable groups indicated that species composition had been modified based on distance from the road. In plots near the road, moisture content, saturation, clay, porosity, and organic carbon decreased, while the amount of sand and silt, bulk density, and pH increased. Findings showed that roads could have significant influence on adjacent ecosystems, and therefore, it is essential to estimate the extent of the road-effect zone and to determine the environmental changes due to forest roads. [ABSTRACT FROM AUTHOR]