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We examined the performance of sweetgum (Liquidambar styraciflua L.), cherrybark oak (Quercus pagoda Raf.), and loblolly pine (Pinus taeda L.) in two-species pine-hardwood mixtures (sweetgum : loblolly pine and cherrybark oak : loblolly pine) at various planting densities (1482-1976 trees per hectare (TPH)) over 23 years in northern Louisiana, USA. Species were planted in alternating rows with hardwood establishment occurring 1 year prior to loblolly pine. Mixtures were also compared to loblolly pine monocultures at a common density (1482 TPH) to assess whether mixing improved productivity. Sweetgum exerted more competitive pressure on loblolly pine than cherrybark oak. At final measurement, sweetgum survival statistically exceeded that of loblolly pine across mixture density. Moreover, sweetgum cumulative basal area and volume growth nearly tripled that of loblolly pine in balanced high-density mixtures (1976 TPH, 50 pine : 50 hardwood). In contrast, cherrybark oak basal area and volume growth did not significantly exceed loblolly pine at any density. At a common density (1482 TPH), loblolly pine monoculture cumulative basal area and volume significantly exceeded those of mixtures with sweetgum and cherrybark oak by 19% and 24%, respectively. Collectively, these results indicate that growing loblolly pine in mixture with these two species did not produce complementary interactions and negatively affected stand-level growth. Key words: overyielding, loblolly pine, cherrybark oak, sweetgum, interspecific competition, mixed stands Nous avons examine la performance du copalme d'Amerique (Liquidambar styraciflua L.), du chene a feuilles en pagode (Quercus pagoda Raf.) et du pin a encens (Pinus taeda L.) dans des melanges de pins et de feuillus a deux especes (copalme d'Amerique : pin a encens et chene a feuilles en pagode : pin a encens) a diverses densites de plantation (1482 a 1976 TPH) pendant 23 ans dans le nord de la Louisiane, aux Etats-Unis. Les especes ont ete plantees en rangs alternes, l'etablissement des feuillus ayant lieu un an avant celui des pins a encens. Les melanges ont egalement ete compares aux monocultures de pin a encens a une densite commune (1482 TPH) pour evaluer si le melange ameliorait la productivite. Le copalme d'Amerique a exerce une plus grande pression concurrentielle sur le pin a encens que le chene a feuilles en pagode. Lors de la mesure finale, la survie du copalme d'Amerique a statistiquement depasse celle du pin a encens, quelle que soit la densite du melange. De plus, la croissance cumulative de la zone basale et du volume du copalme d'Amerique a presque triple par rapport a celle du pin a encens dans les melanges equilibres a haute densite (1976 TPH, 50 pins : 50 feuillus). En revanche, la croissance de la surface terriere et du volume du chene a feuilles en pagode n'a pas depasse de maniere significative celle du pin a encens, quelle que soit la densite. A une densite commune (1482 TPH), la zone basale et le volume cumules de la monoculture du pin a encens ont depasse de maniere significative ceux des melanges avec le copalme d'Amerique et le chene a feuilles en pagode de 19% et 24%, respectivement. Collectivement, ces resultats indiquent que la culture du pin a encens en melange avec ces deux especes n'a pas produit d'interactions complementaires et a affecte negativement la croissance au niveau du peuplement. [Traduit par la Redaction] Mots-cles : rendement excessif, pin a encens, chene a feuilles en pagode, copalme d'Amerique, competition interspecifique, peuplements mixtes, Introduction Maintaining productive forests is a global priority. Historically, monocultures have been established to maximize forest productivity (Rubilar et al. 2018). However, concerns over declining biodiversity, enhanced risk of species-specific [...]

HEPScore is a new CPU benchmark created to replace the HEPSPEC06 benchmark that is currently used by the WLCG for procurement, computing resource pledges, usage accounting and performance studies. The development of the new benchmark, based on HEP applications or workloads, has involved many contributions from software developers, data analysts, experts of the experiments, representatives of several WLCG computing centres and WLCG site managers. In this contribution, we review the selection of workloads and the validation of the new HEPScore benchmark.

Reestablishing appropriate tree species is an important step in converting off‐site monocultures into woodlands. Species conversion is often necessary, as off‐site exotic species rarely function like woodland species. However, when off‐site tree species are native, and functionally redundant to woodland species, conversion may be unnecessary. To explore this possibility in the southeastern United States, we reviewed the literature on trait differences among the primary southern pines and qualitatively assessed the effect of their identity at the species and stand‐levels. In this region, woodland restoration focuses on removing loblolly (Pinus taeda) and slash pine (P. elliottii) to reestablish longleaf (P. palustris) or shortleaf pine (P. echinata). Our review found minimal variation among species in understory flammability, fire resistance at maturity, and Red‐cockaded Woodpecker (Leuconotopicus borealis) habitat at the stand‐level. Longleaf and shortleaf pine were generally more resistant to abiotic and pest disturbance at the tree‐level; however, stand‐level differences in wind, drought, and boring insect resistance among southern pines growing in open forests were considered minimal. Retaining loblolly and slash pine will improve stand‐level productivity in the short term, but creates regeneration problems due to low juvenile fire resistance and resilience. Ice resistance and long‐term carbon sequestration will also likely be reduced by retaining loblolly and slash pine. Collectively, these results suggest that southern pine species are generally interchangeable at the stand‐level in woodlands; although woodlands featuring loblolly and slash pine may be less stable in the face of disturbance than those dominated by shortleaf and longleaf pine. [ABSTRACT FROM AUTHOR]

Summary: Many trees exhibit masting – where reproduction is temporally variable and synchronous over large areas. Several dominant masting species occur in tropical cyclone (TC)‐prone regions, but it is unknown whether TCs correlate with mast seeding.We analyzed long‐term data (1958–2022) to test the hypothesis that TCs influence cone production in longleaf pine (Pinus palustris). We integrate field observations, weather data, satellite imagery, and hurricane models to test whether TCs influence cone production via: increased precipitation; canopy density reduction; and/or mechanical stress from wind.Cone production was 31% higher 1 yr after hurricanes and 71% higher after 2 yr, before returning to baseline levels. Cyclone‐associated precipitation was correlated with increased cone production in wet years and cone production increased after low‐intensity winds (≤ 25 m s−1) but not with high‐intensity winds (> 25 m s−1).Tropical cyclones may stimulate cone production via precipitation addition, but high‐intensity winds may offset any gains. Our study is the first to support the direct influence of TCs on reproduction, suggesting a previously unknown environmental correlate of masting, which may occur in hurricane‐prone forests world‐wide. See also the Commentary on this article by Pearse & Wion, 242: 8–9. [ABSTRACT FROM AUTHOR]

Once dominant across the United States (US) Southeastern Coastal Plain, the longleaf pine (Pinus palustris Mill.) ecosystem covers a fraction of its historic geographic range. Restoration efforts have largely occurred on public lands, while most private forests feature alternative pine species. A better understanding of public interest in ecological restoration is critical to sustained efforts and successes. This research examines both forest landowner and general public interest in longleaf pine restoration. Results contribute to research on the social dimensions of ecological restoration, much of which has focused on small-scale projects rather than landscape-scale initiatives. In addition, this study addresses the lack of knowledge regarding factors driving attitudes towards ecological restoration other than demographic and psychometric variables. We employed a telephone survey of 2700 participants across eight states in the southeastern US in the historical range of longleaf pine. A majority of respondents supported restoration as a general goal and were supportive of the use of prescribed fire as a restoration practice. Place attachment, knowledge about longleaf pine, and age were among the significant predictors of restoration support. Findings have implications for future research focusing on sociocultural influences of restoration projects, as well as expanded public support for restoration of fire-maintained ecosystems. Key words: longleaf pine, place attachment, restoration, prescribed fire, southeastern US. Autrefois dominant dans la plaine cotiere du sud-est des Etats-Unis, l'ecosysteme du pin des marais (Pinuspalustris Mill.) occupe une fraction de l'aire de repartition qu'il occupait. Les efforts de restauration ont surtout ete orientes vers les terres publiques, tandis que la plupart des forets privees sont occupees par d'autres especes de pin. Une meilleure comprehension de l'interet du public pour la restauration ecologique est essentielle pour maintenir les efforts et les succes. Cette recherche explore l'interet des proprietaires forestiers et du grand public pour la restauration du pin des marais. Les resultats contribuent a la recherche sur les dimensions sociales de la restauration ecologique qui a surtout mis l'accent sur les projets a petite echelle plutot que sur les initiatives a l'echelle du paysage. De plus, cette etude s'interesse au manque de connaissance sur les facteurs qui determinent les attitudes envers la restauration ecologique, autres que les variables demographiques et psychometriques. Nous avons realise une enquete telephonique aupres de 2700 participants dans huit Etats du sud-est des Etats-Unis dans l'aire de repartition historique du pin des marais. Une majorite de repondants supportait la restauration comme objectif general et etait en faveur de l'utilisation du brulage dirige comme methode de restauration. L'attachement a un lieu, la connaissance du pin des marais et l'age etaient parmi les predicteurs significatifs du support pour la restauration. Les resultats ont des implications pour les recherches futures qui devraient mettre l'accent sur les influences socioculturelles des projets de restauration ainsi que sur l'elargissement du support publique pour la restauration des ecosystemes maintenus par le feu. [Traduit par la Redaction] Mots-cles: pin des marais, attachement a un lieu, restauration, brulage dirige, sud-est des Etats-Unis., Introduction Once dispersed across approximately 57 million acres (23 million ha) of the Southeastern Coastal Plain, longleaf pine (LLP; Pinus palustris Mill.) covers a fraction of its original native range, [...]

Pruning or the physical removal of lower branches, in combination with wider tree spacing, offers an alternative management scheme for small nonindustrial private forest landowners in areas lacking markets for small diameter wood. A 5-year-old loblolly pine (Pinus taeda) plantation was thinned to 495 trees/ha (200 trees/ac). Four crown-lifting treatments of 35%, 40%, 45%, and 50% live crown ratio (LCR) were then implemented. An additional unmanaged plot was established in an unthinned, unpruned area. Two replications were established for all pruning treatments. The target LCR was maintained throughout the study with the additional crown-lifting activities in 2003, 2004, and 2008. At age 8, the average diameter of the unmanaged plot was 13.5 cm (5.3 in), and the diameter of the 50% LCR treatment, which had the greatest diameter growth of all the treatments, was 20.8 cm (8.2 in). The highest mortality rate (22%) was observed in the unmanaged plot, but it was not significantly greater than the other treatments. Low density plantings maintained with pruning could allow small nonindustrial private landowners to obtain a high value sawtimber product while eliminating the need for thinning practices commonly used in traditional pine plantation management. [ABSTRACT FROM AUTHOR]

Tree species distributions and diversity could be explained by rank changes in performance over multiple spatiotemporal resource gradients, i.e., resource partitioning. For 14 species planted in 45 harvest gap and closed canopy locations in a mesic northern hardwood forest community, Michigan, USA, we asked the following questions: (i) are species growth responses to light, nitrogen (N), or N form (ammonium vs. nitrate) related to their ecological distributions and phylogenies? and (ii) is there evidence of growth-based resource partitioning over measured resource gradients? Growth responses to the N form were consistent with both differences in uptake energy requirements between N forms and their availability through succession and across fertility gradients; height growth was negatively related to the species shade-tolerance score, especially in high light, i.e., shade-intolerant species responded to soil nitrate-N and shade-tolerant species responded to ammonium-N; fertile soil associated species responded to nitrate-N and infertile soil associated species to ammonium-N; and gymnosperms responded to ammonium-N and angiosperm responses varied. Modeled growth responses to resources showed only modest evidence for rank changes over resource gradients, with N contributing less to rank changes than light. Thus, growth responses to resources were accurately predicted by species ecology and (or) phylogeny; however, there was only modest support for the notion that growth-based resource partitioning underlies community-scale diversity in a northern hardwood forest. Key words: height growth, shade tolerance, soil nitrogen, nitrate, ammonium, tree diversity. La distribution et la diversite des especes d'arbre pourraient etre expliquees par des changements de classe de performance selon de multiples gradients spatiotemporels de ressources, c'est-a-dire la repartition des ressources. Pour 14 especes plantees a 45 endroits (trouee forestiere ou couvert ferme) dans une communaute de feuillus nordiques etablie sur une station mesique du Michigan, aux Etats-Unis, nous avons pose les questions suivantes: (i) est-ce que la reaction de croissance des especes a la lumiere, a l'azote (N) ou a la forme de N (ammonium ou nitrate) est reliee a leur distribution ecologique et a leur phylogenie? et (ii) est-ce qu'il y a des signes de repartition des ressources fondee sur la croissance selon le gradient des ressources mesurees? La croissance en hauteur etait negativement reliee au degre de tolerance a l'ombre des especes, particulierement en conditions de forte luminosite. En fonction des gradients de succession et de fertilite, la reaction de croissance a N etait generalement coherente avec la disponibilite des formes de N et des exigences energetiques pour leur absorption : les especes intolerantes a l'ombre reagissaient a N du sol sous forme de nitrate et les especes tolerantes a l'ombre a N sous forme d'ammonium; les especes associees aux stations fertiles reagissaient a N sous forme de nitrate et les especes associees aux sols infertiles a N sous forme d'ammonium; les gymnospermes reagissaient a N sous forme d'ammonium alors que la reaction des angiospermes variait. La reaction modelisee de croissance aux ressources ne montrait que des signes modestes de changements de classe selon le gradient des ressources et N contribuait moins aux changements de classe que la lumiere. Ainsi, la reaction de croissance aux ressources etait predite correctement par l'ecologie et la phylogenie des especes, mais il n'y avait qu'un appui modeste a la notion voulant que la repartition des ressources fondee sur la croissance soit a l'origine de la diversite a l'echelle de la communaute dans les forets de feuillus nordiques. [Traduit par la Redaction] Mots-cles: croissance en hauteur, tolerance a l'ombre, azote du sol, nitrate, ammonium, diversite des arbres., Introduction A popular hypothesis proposed to explain tree diversity is that species have specialized regeneration niches and thus are able to coexist by partitioning complex environments (Grubb 1977). For trees, [...]

Intensive pine silviculture has become the dominant management paradigm in the southeastern United States. Although productivity has been substantially increased by the combination of cultural, silvicultural, and genetic advancements, wood quality is sometimes sacrificed in intensive silviculture. Extending the optimal rotation allows trees to grow more timber, which may result in the production of better quality sawtimber; however, landowners may require incentives to do so. We simulated loblolly, slash, shortleaf, and longleaf pine for growth and yield using the Forest Vegetation Simulator (FVS) to determine sawtimber price premiums landowners would require to offset the costs associated with delaying the final harvest by 10 to 30 years in even-aged systems. Required incentives increased with the length of harvesting delay beyond the financially optimal rotation age. On medium productivity sites, landowners would be willing to delay the final harvest by 10 years for sawtimber price premiums of $5.06/ton (20.47%) for loblolly, $5.34/ton (21.6%) for slash, $4.56/ton (18.45%) for longleaf, and $6.71/ton (27.14%) shortleaf pine, respectively. Harvest delays of 10 to 20 years were financially justifiable, whereas extensions exceeding 30 years were prohibitively costly for all species. Delaying the optimal harvest could benefit landowners by generating a premium price for their sawtimber while providing important ecosystem services. [ABSTRACT FROM AUTHOR]