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Marshallia legrandii (Oak Barrens Barbara's-buttons) is a critically imperiled perennial herb in North Carolina and Virginia's Piedmont region. We completed a flowering census of this species at 2 of its 3 known populations in 2021, and again at the largest of those measured populations in 2022. We compared flowering density with canopy openness at both sites. At the largest population, we also measured competing vegetation, soil properties, and Oak Barrens Barbara's-buttons density to describe its habitat. Here, we also implemented an experimental augmentation of Oak Barrens Barbara's-buttons to monitor planting survival and growth under different light environments. We found that Oak Barrens Barbara's-buttons can flower under a broader range of canopy openness than previously believed. In addition to light, we found that competing vegetation, soil temperature, and soil moisture are important predictors of flowering success. Survival of augmented Oak Barrens Barbara's-buttons was nearly 90%, and 28–42% of plants bloomed 2 years after planting. [ABSTRACT FROM AUTHOR]

Ludwigia ravenii (G1G2) is a wetland-obligate perennial, endemic to the Atlantic Coastal Plain. The species appears to be relegated to roadside ditches and ruts, and is under review for federal listing. The objectives of this study were to quantitatively assess biotic and abiotic habitat characteristics of extant populations and augment knowledge of the species ecology. Two congeners were selected for comparative analysis: L. alternifolia and L. pilosa. Over two field seasons, data were collected from 108 1 m2 quadrats and variable length transects across the species range. All 17 element occurrences of L. ravenii on record during the 2020--2021 sampling period were visited and 15 (nplots=62) were sampled. Forty-six plots at 14 sites were collectively sampled for the target congeners (L. alternifolia, nplots=27; L. pilosa, nplots=19). Variables assessed included: physical ditch dimensions, aspect, elevation, canopy cover, abiotic and vegetative cover, and edaphic variables (nutrient composition and pH). Data were visualized using NMS and PCA, and analyzed using ANOVA and post-hoc tests. Only PCA showed distinct clustering of quadrats of L. ravenii along soil fertility gradients. Quadrats of L. ravenii exhibited median values compared to congeners in many measured variables, including canopy cover, species richness, and Shannon's diversity index. Quadrats of L. ravenii differed most strongly from congeners by more acidic mean soil pH (4.68±0.05). Although no single species emerged as an ideal indicator, the combination of L. linearis and Kellochloa verrucosa was found highly suggestive of suitable habitat for L. ravenii. [ABSTRACT FROM AUTHOR]

Branches reduce stem quality, and the level of the effect is determined by the geometry, size, and number, of associated knots. Quantifying branchiness is difficult, as visual estimates are subjective, and mechanical measurements are impractical. Acoustic velocity (AV) is a relatively novel measurement capturing the speed stress travels through wood. AV is correlated with wood stiffness and is affected by internal characteristics like knots. This project tested AV as an indirect branchiness metric by measuring AV, height, diameter, and counting branches classified by diameter on 255 standing 8 year old longleaf pine (Pinus palustris). AV was highly correlated with height (r = 0.76, p < 0.0001) and slenderness (r = 0.52, p < 0.0001). AV was moderately correlated with large living branches (diameter > 2.54 cm) (r = −0.27, p < 0.0001), but not correlated with total branches. Height, slenderness, and the count of large living branches (diameter > 2.54 cm) were included in the selected model for AV. Inclusion of dead or small (diameter < 2.54 cm) branches reduced model power. The best model captured 11% of the variation in AV, of which branches explained 5%. We conclude that AV does not appropriately quantify individual tree branchiness, but may be suitable for comparing populations such as families or provenances. [ABSTRACT FROM AUTHOR]

Dead woody material (DWM) plays numerous important roles in forest ecosystems; however, through the process of decomposition, it undergoes structural and chemical changes that progressively alter its function in these roles. Much remains unknown about how DWM mechanical strength and structural integrity change through decomposition in natural forest settings. We assessed changes in wood strength (bending strength, compressive strength, and surface hardness) using standard wood stakes of known initial mass from three species. The stakes were placed in forested settings for two and four years before collection for laboratory analyses. All three strength metrics decreased as stakes lost mass due to decay; however, bending strength had the strongest relationship with mass loss, a result that was consistent for all species, as well as species-pooled data. Results for all strength-loss metrics indicate that stakes had experienced ca. 10% strength loss before any detectable mass loss had occurred. Further, our results suggest that the decay class system typically used during field inventories--based in large part on tactile assessments of wood structural integrity--may provide a reasonable characterization of DWM mass loss, which is a critical assumption for carbon accounting and modelling based on inventory data. Key words: carbon accounting, decay class, decay stakes, forest fuels, wood decay, woody debris. Le materiel ligneuxgrossier (MLG) joue plusieurs roles importants dans les ecosystemes forestiers. Cependant, durant le processus de decomposition il subit des changements structuraux et chimiques qui modifient progressivement les fonctions associees a ces roles. Beaucoup de choses demeurent inconnues au sujet de la facon dont la resistance mecanique et l'integrite structurale du MLG changent durant sa decomposition en foret naturelle. Nous avons evalue les changements dans la resistance du bois (resistance a la flexion, resistance a la compression et durete superficielle) a l'aide de baguettes de bois standards dont on connaissait la masse initiale de trois especes. Les baguettes ont ete laissees en foret pendant deux et quatre ans avant d'etre recoltees pour les analyses en laboratoire. Les resultats des trois mesures de resistance ont diminue a mesure que progressait la perte de masse due a la decomposition des baguettes. Cependant, la resistance a la flexion etait le plus etroitement reliee a la perte de masse, un resultat constant chez toutes les especes ainsi qu'avec les donnees des especes regroupees. Les resultats pour toutes les mesures de perte de resistance indiquent que les baguettes avaient subi une perte de resistance d'environ 10 % avant que survienne une perte de masse detectable. De plus, nos resultats confirment que le systeme de classes de decomposition normalement utilise lors des inventaires terrestres, fonde en grande partie sur des evaluations tactiles de l'integrite structurale du bois, fournit une approximation raisonnable de la perte de masse du MLG, laquelle est essentielle pour la modelisation et la comptabilisation precise du carbone sur la base des donnees d'inventaire. [Traduit par la Redaction] Mots-cles: comptabilisation du carbone, classe de decomposition, baguettes de bois servant a mesurer la decomposition, combustibles forestiers, decomposition du bois, debris ligneux., Introduction Dead woody material (DWM) plays a crucial role in forest ecosystems where it contributes to carbon storage, nutrient cycling, and biodiversity maintenance (Harmon et al. 1986; Stokland et al. [...]

Restoring structural features of old-growth forests, such as increased canopy gap sizes and coarse woody debris, is a common management goal for second-growth, even-aged stands. We experimentally manipulated forest structure by creating variable-size canopy gaps in a second-growth northern hardwood forest in north-central Wisconsin following two growing seasons of pre-treatment monitoring. The objectives of this study were to quantify the influence of canopy gaps of different sizes (50-380 [m.sup.2]) on aboveground biomass and productivity of each vegetation stratum two growing seasons following treatment. Two years after treatment, ground layer biomass in canopy openings increased significantly relative to surrounding undisturbed transition zones. The response of ground layer biomass was greatest in the large versus the medium and small gaps. Sapling aboveground net primary productivity was significantly greater in undisturbed transition zones than within gaps across gap sizes following the second post-treatment growing season. Annual stem diameter increment was greatest for trees along gap borders and was correlated with crown class, percentage of crown perimeter exposed, gap area, and shade tolerance. Total aboveground net primary productivity was significantly lower in the gap addition plots the first year but by the second post-treatment growing season no longer differed from that in the control plots. Resume: La restauration des attributs structuraux des vieilles forets, tels que des trouees de plus grande taille dans la canope e et davantage de gros debris ligneux, est une pratique d'amenagement usuelle dans les peuplements equiennes de seconde venue. Nous avons modifie experimentalement la structure forestiere en creant des trouees de taille variable dans la canopee d'une foret de feuillus nordiques de seconde venue etablie dans le centre-nord du Wisconsin. Ce travail a ete precede d'un suivi pretraitement pendant deux saisons de croissance. Les objectifs de cette etude etaient de quantifier l'influence des trouees de taille variable (de 50 a 380 [m.sup.2]) dans la canopee sur la biomasse aerienne et la productivite de chaque strate de la vegetation apres les deux saisons de croissance qui ont suivi l'application du traitement. Deux ans apres le traitement, la biomasse de la vegetation au sol dans les ouvertures de la canopee avait significativement augmente par rapport aux zones de transition environnantes non perturbees. La reaction de la biomasse de la vegetation au sol etait plus forte dans les grandes ouvertures que dans les moyennes et petites ouvertures. La productivite primaire nette aerienne des gaules etait significativement plus grande dans les zones de transition non perturbees qu'a l'interieur des trouees pour toutes les tailles de trouees apres deux saisons de croissance. L'accroissement annuel en diametre des tiges etait plus eleve chez les arbres situes en bordure des trouees et etait correle a la classe de cime, au pourcentage du perimetre de la cime expose, a la superficie de la trouee et a la tolerance a l'ombre. La productivite primaire nette aerienne totale etait significativement plus faible dans les placettes situees dans les trouees que dans les placettes temoins au cours de la premiere anne e, mais cette difference disparaissait au cours de la deuxieme saison de croissance apres l'application du traitement. [Traduit par la Redaction], Introduction Foresters and ecologists have long been interested in the influence of silvicultural systems or disturbances on ecosystem structure and function. The need for this information has increased as demands [...]

Questions: How do deer mediate the response of forest ground‐layer plant communities to canopy gap size? Location: Flambeau River State Forest in north central Wisconsin, USA (47°37.4ʹ N, 90°47.8ʹ W). Method: We examined responses of resources, growth forms and temporal guilds to factorial combinations of canopy gap treatments consisting of a range of gap sizes (80, 200 and 380 m2), and deer (Odocoileus virginianus) exclusion (0.64 ha fenced exclosures) 4 years following gap creation (3 years following deer exclusion). We contrasted responses in central and transition zones. Results: In the absence of deer, forb productivity increased from pre‐treatment levels, particularly where light transmittance and soil moisture were high. In contrast, forb productivity decreased in the presence of deer. These effects were stronger among forbs with early‐ and late‐summer leafing phenology than spring ephemeral, and evergreen species. In contrast, deer amplified increases in graminoid productivity, which were related primarily to light transmittance. Deer did not alter responses of ferns, shrubs, trees seedlings or vines. Canopy gaps increased community heterogeneity among gap sizes and zones, but only in the absence of deer. This was related to the effects of deer on the composition and diversity of gap specialists. Conclusions: The maintenance of biodiversity in northern temperate forest ground‐layer plant communities by canopy gap dynamics appears to hinge on deer herbivory, even at relatively modest populations of deer and a productive site. Conversely, increases in resource availability within gaps may function to mitigate some negative effects of deer on forb productivity. Effects may be transient, as species turnover to shrub‐ and sapling‐dominated communities and canopy closure may cause communities to converge in the future. However, populations of undefended gap specialists remain particularly sensitive. [ABSTRACT FROM AUTHOR]