Phenotypic plasticity enables considerable acclimation to heat and drought in a cold-adapted boreal forest tree species

Increasing frequencies of severe heat waves and drought are expected to influence the composition and functioning of ecosystems globally. Our ability to predict and mitigate these impacts depends on our understanding of species- and age-specific responses to these stressors. To assess the adaptive capacity of balsam fir to climate change, a cold-adapted boreal tree species, we conducted a climate-controlled greenhouse experiment with four provenances originating from across the species biogeographic range, 12 temperature treatments ensuring a minimum of +11°C warming, and five drought treatment intensities. We found considerable acclimation to temperature and drought treatments across all provenances, with steady gains in biomass under temperatures well-beyond the “worst-case” (RCP 8.5) climate forcing scenario within the species natural range. Acclimation was supported by high phenotypic plasticity in root:shoot ratio (RSR) and photosynthesis, which were greatly increased with warming, but were not affected by drought. Our results suggest that regardless of the observed provenance variation, drought and heat are not limiting factors of the current-year balsam fir seedling growth, instead, these factors may be more impactful on later stages of regeneration or previously stressed individuals, thus highlighting the necessity of incorporating the factors of ontogeny and provenance origin in future research regarding plant and climate interactions

The changing culture of silviculture

Changing climates are altering the structural and functional components of forest ecosystems at an unprecedented rate. Simultaneously, we are seeing a diversification of public expectations on the broader sustainable use of forest resources beyond timber production. As a result, the science and art of silviculture needs to adapt to these changing realities. In this piece, we argue that silviculturists are gradually shifting from the application of empirically derived silvicultural scenarios to new sets of approaches, methods and practices, a process that calls for broadening our conception of silviculture as a scientific discipline. We propose a holistic view of silviculture revolving around three key themes: observe, anticipate and adapt. In observe, we present how recent advances in remote sensing now enable silviculturists to observe forest structural, compositional and functional attributes in near-real-time, which in turn facilitates the deployment of efficient, targeted silvicultural measures in practice that are adapted to rapidly changing constraints. In anticipate, we highlight the importance of developing state-of-the-art models designed to take into account the effects of changing environmental conditions on forest growth and dynamics. In adapt, we discuss the need to provide spatially explicit guidance for the implementation of adaptive silvicultural actions that are efficient, cost-effective and socially acceptable. We conclude by presenting key steps towards the development of new tools and practical knowledge that will ensure meeting societal demands in rapidly changing environmental conditions. We classify these actions into three main categories: reexamining existing silvicultural trials to identify key stand attributes associated with the resistance and resilience of forests to multiple stressors, developing technological workflows and infrastructures to allow for continuous forest inventory updating frameworks, and implementing bold, innovative silvicultural trials in consultation with the relevant communities where a range of adaptive silvicultural strategies are tested. In this holistic perspective, silviculture can be defined as the science of observing forest condition and anticipating its development to apply tending and regeneration treatments adapted to a multiplicity of desired outcomes in rapidly changing realities

Spatio-temporal divergence in the responses of Finland's boreal forests to climate variables

Spring greening in boreal forest ecosystems has been widely linked to increasing temperature, but few studies have attempted to unravel the relative effects of climate variables such as maximum temperature (TMX), minimum temperature (TMN), mean temperature (TMP), precipitation (PRE) and radiation (RAD) on vegetation growth at different stages of growing season. However, clarifying these effects is fundamental to better understand the relationship between vegetation and climate change. This study investigated spatio-temporal divergence in the responses of Finland's boreal forests to climate variables using the plant phenology index (PPI) calculated based on the latest Collection V006 MODIS BRDF-corrected surface reflectance products (MCD43C4) from 2002 to 2018, and identified the dominant climate variables controlling vegetation change during the growing season (May-September) on a monthly basis. Partial least squares (PLS) regression was used to quantify the response of PPI to climate variables and distinguish the separate impacts of different variables. The study results show the dominant effects of temperature on the PPI in May and June, with TMX, TMN and TMP being the most important explanatory variables for the variation of PPI depending on the location, respectively. Meanwhile, drought had an unexpectedly positive impact on vegetation in few areas. More than 50 % of the variation of PPI could be explained by climate variables for 68.5 % of the entire forest area in May and 87.7 % in June, respectively. During July to September, the PPI variance explained by climate and corresponding spatial extent rapidly decreased. Nevertheless, the RAD was found be the most important explanatory variable to July PPI in some areas. In contrast, the PPI in August and September was insensitive to climate in almost all of the regions studied. Our study gives useful insights on quantifying and identifying the relative importance of climate variables to boreal forest, which can be used to predict the possible response of forest under future warming.Peer reviewe

Can plantations develop understory biological and physical attributes of naturally regenerated forests?

With an increasing proportion of natural forests being replaced by plantations, there is a need to determine their potential to fulfill ecological purposes other than wood production. This study evaluated the extent to which deciduous and coniferous plantations develop understory attributes comparable to those of naturally regenerated stands. A functional group approach was used to synthesise species responses in terms of their ecological traits. Multivariate analyses of ecological traits revealed 16 emergent groups that shared common traits associated with a similar life history strategy. Responses of these groups, understory structure, and understory environmental conditions to plantation types and stand stages were analyzed and compared to naturally regenerated stands. Clear associations of trait responses to stand developmental stages and plantation types emerged. Light-demanding and wind-dispersed species groups were associated with early-successional stages, while woody groups, ferns and ant-dispersed spring-flowering herbs were associated with late-successional stages. Analyses also revealed an indicator group associated with old naturally regenerated forest. The understory functional groups and environmental conditions of deciduous plantations converged toward those of old naturally regenerated forests. However, understory structure in deciduous plantations remained poorly developed and richness of the indicator group was low compared to unplanted stands. Conifer plantations, currently the most common plantation type in the northern hardwood biome, showed a completely different pathway of understory development. Modifications to current plantation management practices are proposed to help recreate or maintain natural understory biological and physical attributes

Effects of soil warming and nitrogen foliar applications on bud burst of black spruce

Key message: In mature black spruce, bud burst process is anticipated by soil warming, while delayed by foliar applications of nitrogen; however, the effects depend on growth conditions at the site. Abstract: The observation of phenological events can be used as biological indicator of environmental changes, especially from the perspective of climate change. In boreal forests, the onset of the bud burst is a key factor in the length of the growing season. With current climate change, the major factors limiting the growth of boreal trees (i.e., temperature and nitrogen availability) are changing and studies on mature trees are limited. The aim of this study was to investigate the effects of soil warming and increased nitrogen (N) deposition on bud burst of mature black spruce [Picea mariana (Mill.) BSP]. From 2008 onwards, an experimental manipulation of these environmental growth conditions was conducted in two stands (BER and SIM) at different altitudes in the boreal forest of Quebec, Canada. An increase in soil temperature (H treatment) and a canopy application of artificial rain enriched with nitrogen (N treatment) were performed. Observations of bud phenology were made during May–July 2012 and 2013. In BER, H treatment caused an anticipation (estimated as 1–3 days); while N treatment, a delay (estimated as 1–2 days but only in 2012) in bud burst. No treatments effect was significant in SIM. It has been demonstrated that soil temperature and N availability can play an important role in affecting bud burst in black spruce but the effects of these environmental factors on growth are closely linked with site conditions

La fierté d’être anormal : valorisation des stigmas comme nouvelle identité chez les lolita et angura à Tokyo

Downtown districts of Tokyo are well known for the eccentric fashion style of some individuals, especially around Shinjuku, Harajuku, Shibuya or Roppongi. Some of them are part of large subcultural communities and have an active role in the cultural life of Tokyo, expressing themselves through fashion events, shows, dance parties or art exhibits. The lolita, gothics, angora (“underground”), fetishists and others have formed a culturally and aesthetically marginal community. This study explores identity formation of subculture community members and the discourse of “perversion” and “abnormality.” The latter has become a key word in their “marginal” identity, grounding their activities and serving as esthetical resistance to the dominant culture.Les quartiers du centre de Tokyo sont reconnus mondialement pour l’excentricité esthétique de certains individus qu’on y retrouve, notamment à Shinjuku, Harajuku, Shibuya ou Roppongi. Ils forment des communautés de sous-culture et participent activement à la vie culturelle de la ville à travers des évènements de mode, des spectacles, des soirées de danse ou des expositions artistiques. Les lolita, les gothiques, les angura (« underground ») et les fétichistes forment, à travers ces évènements, une communauté esthétiquement et culturellement marginale. Cette note de recherche se penche sur la construction identitaire des membres de ces communautés et sur le discours de l’« anomalie » et de la « perversion » comme élément clé de leur identité « marginale ». Leur identité en tant qu’« anormaux » est centrale à leurs activités et se veut une résistance esthétique contre la culture dominante

Stigmatisation de la jeunesse japonaise par le discours et les représentations de la délinquance juvénile (1997-2010)

À la suite de certains grands meurtres commis en 1997 et 2000 par des jeunes de 14 et 17 ans, un discours sur les délinquants juvéniles comme étant plus violents, plus cruels, plus anormaux et plus nombreux que jamais auparavant s’installait chez les intellectuels et dans les médias japonais. Or, par dérapage analytique, ce discours a été généralisé à tous les jeunes, qui ont été considérés comme étant des individus violents, incompréhensibles, anormaux et potentiellement criminels malgré une certaine normalité apparente, faisant d’eux des dangers pour la nation. Cette étude présente le développement du discours stigmatisant la jeunesse des années 2000, en présentant les concepts clés qui ont été utilisés comme caractéristiques ainsi que comme arguments de la monstruosité cachée chez les jeunes Japonais.Five murders in Japan committed by juvenile criminals attracted immense attention from the media in the years 1997 and 2000. A new discourse about juvenile delinquency followed these incidents, stipulating that juvenile delinquents had become more cruel, more violent, more abnormal, and more numerous than ever before. However, the discourse developed on its own, taking a radical ideological turn : it began to apply not only to juvenile delinquents, but labelled the entire population of Japanese youth as dangerous, incomprehensible, and abnormal while seeming to be proper and normal members of society. The discourse strongly influenced the Japanese society ideologically and legally, and labelled its youth as a threat to the nation. This study presents the development of this particular discourse that led to the negative portrayal of the Japanese youth in the first decade of the 21st century. Key concepts used as characteristics of this cohort are examined, breaking down the discourse into sociocultural and ideological reasoning and systems.Debido a ciertas grandes muertes cometidas entre 1997 y 2000 por jóvenes entre 14 y 17 años, un discurso sobre los delincuentes juveniles, supuestamente más violentos, más crueles, más anormales y más numerosos que nunca antes, se instaló entre los intelectuales y los medios japoneses. Ahora bien, gracias a un derrape analítico, ese discurso ha sido aplicado a todos los jóvenes, considerándolos como individuos violentos, incomprensibles, anormales, potencialmente criminales, a pesar de su normalidad aparente, convirtiéndolos en un peligro para la nación. Este estudio presenta el desarrollo del discurso de estigmatización de la juventud de los años 2000, presentando los conceptos clave utilizados como características y argumentos de la monstruosidad escondida entre los jóvenes japoneses

A three-year increase in soil temperature and atmospheric N deposition has minor effects on the xylogenesis of mature balsam fir

Tree growth in most boreal forests is strongly regulated by temperature and nitrogen (N) availability. The expected increases in soil temperature and N deposition over the next decades have the potential to affect the phenology of tree growth and xylogenesis. To test for these changes on xylogenesis of balsam fir (Abies balsamea (L.) Mill), 12 mature trees were subjected to a combination of experimentally increased soil temperature (+4 °C) with an earlier snowmelt (2-3 weeks) and N deposition (3 × ambient rain N concentrations using NH4-NO3 in artificial precipitation) over a 3-year period. Increased soil temperature and atmospheric N deposition had no significant effect on the number of tracheids produced (38-51), tracheid diameter (27.2-29.0 μm) and cell wall thickness (2.5-3.1 μm). For the 3 years of treatment, xylogenesis was initiated at minimum and average daily air temperatures of 0.6 ± 0.5 and 6.5 ± 0.6 °C, respectively, with inter-annual differences of 17 days in the onset of xylogenesis. The earlier snowmelt induced by soil warming did not hasten resumption of xylogenesis, and the time dynamics of xylogenesis was not affected by higher N deposition. Our results suggest that soil temperature and the timing of snowmelt have no direct influence on the breaking of cambium dormancy in balsam fir. The short-term effects of increased soil temperature and N deposition on xylogenesis of mature balsam fir appear to be small compared with the effects of air temperature and are likely to be associated with a persistent N limitation

Beneficial effects of climate warming on boreal tree growth may be transitory

The productivity of boreal forests in Eastern North America is predicted to increase with warming under sufficient moisture supply. Here D’Orangeville et al. study seven tree species and predict that growth enhancements may be seen up to 2 °C warming, but would decline if temperatures exceed this