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Fire is an integral component of ecosystems globally and a tool that humans have harnessed for millennia. Altered fire regimes are a fundamental cause and consequence of global change, impacting people and the biophysical systems on which they depend. As part of the newly emerging Anthropocene, marked by human-caused climate change and radical changes to ecosystems, fire danger is increasing, and fires are having increasingly devastating impacts on human health, infrastructure, and ecosystem services. Increasing fire danger is a vexing problem that requires deep transdisciplinary, trans-sector, and inclusive partnerships to address. Here, we outline barriers and opportunities in the next generation of fire science and provide guidance for investment in future research. We synthesize insights needed to better address the long-standing challenges of innovation across disciplines to (i) promote coordinated research efforts; (ii) embrace different ways of knowing and knowledge generation; (iii) promote exploration of fundamental science; (iv) capitalize on the "firehose" of data for societal benefit; and (v) integrate human and natural systems into models across multiple scales. Fire science is thus at a critical transitional moment. We need to shift from observation and modeled representations of varying components of climate, people, vegetation, and fire to more integrative and predictive approaches that support pathways toward mitigating and adapting to our increasingly flammable world, including the utilization of fire for human safety and benefit. Only through overcoming institutional silos and accessing knowledge across diverse communities can we effectively undertake research that improves outcomes in our more fiery future.

We assessed natural regeneration of longleaf pine (Pinus palustris Mill.) using the data collected from the Escambia Experimental Forest in southern Alabama. Fifteen years after the regeneration control, natural regeneration of longleaf pine remained patchy across a wide range of site and stand conditions; slightly more than half of all plots contained regeneration, but the density of seedlings and saplings varied significantly. The abundance of seedlings [less than or equal to] 1- year-old was positively related to stand age and time since last fire, but negatively related to overstory basal area. The abundance of seedlings and saplings was positively related to stand age, but negatively related to time since last fire and overstory basal area. The probability of achieving at least 15 000 seedlings * [ha.sup.-1] that are older than 1 year but less than 1 m tall and at least 1250 saplings * [ha.sup.-1] that are over 1 m tall was, respectively, positively related to the ratio of time since last fire to overstory basal area and the ratio of quadratic mean diameter to site index. A longer fire interval (> 2 to 3 years) should be adopted to naturally regenerate longleaf. We did not find clear zones of exclusion present in natural regeneration even though overstory trees, seedlings, and saplings tended to be repulsive spatially and >80% grass stage seedlings and saplings occurred outside tree crowns. Key words: longleaf pine (Pinus palustris Mill.), natural regeneration, zero- inflated negative binomial model, point pattern data, spatial analysis. Nous avons evalue la regeneration naturelle du pin des marais (Pinus palustris Mill.) en utilisant les donnees recueillies dans la Foret experimentale d'Escambia situee dans le sud de l'Alabama. Quinze ans apres une inspection de la regeneration, la regeneration naturelle du pin des marais etait restee irreguliere malgre une large gamme de conditions de station et de peuplements; un peu plus de la moitie des placettes etaient regenerees, mais la densite des semis et des gaules variait considerablement. L'abondance des semis de moins d'un an etait positivement liee a l'age du peuplement et au temps ecoule depuis le dernier feu, mais negativement liee a la surface terriere du couvert dominant. L'abondance des semis et des gaules etait positivement liee a l'age du peuplement, mais negativement liee au temps ecoule depuis le dernier feu et a la surface terriere du couvert dominant. La probabilite d'obtenir au moins 15 000 semis * [ha.sup.-1] plus vieux qu'un an mais d'une hauteur egale ou inferieure a 1 m, et au moins 1250 gaules * [ha.sup.-1] d'une hauteur superieure a 1 m etait, respectivement, positivement correlee au rapport entre le temps ecoule depuis le dernier feu et la surface terriere du couvert dominant et au rapport entre le diametre quadratique moyen et l'indice de qualite de station. Un intervalle de feu plus long (plus de 2 a 3 ans) devrait etre adopte pour regenerer naturellement le pin des marais. Nous n'avons pas trouve de zones claires d'exclusion de la regeneration naturelle meme si les arbres du couvert dominant, les semis et les gaules avaient tendance a etre spatialement repulsifs et que plus de 80 % des petits semis et des gaules etaient etablis hors de la projection de la cime des arbres. [Traduit par la Redaction] Mots-cles: pin des marais (Pinus palustris Mill.), regeneration naturelle, modele binomial negatif a exces de zero, donnees par patron de points, analyse spatiale., Introduction The longleaf pine (Pinus palustris Mill.) forest ecosystem in the southern United States is a unique ecological community that has experienced a drastic reduction in area, from approximately 37.2 [...]

Trees in dry forests often regenerate in episodic pulses when wet periods coincide with ample seed production. Factors leading to success or failure of regeneration pulses are poorly understood. We investigated the impacts of stand thinning on survival and growth of the 2013 cohort of ponderosa pine (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) seedlings in northern Arizona, United States. We measured seedling survival and growth over the first five growing seasons after germination in six stand basal areas (BAs; 0, 7, 14, 23, 34, and 66 (unthinned) [m.sup.2]*[ha.sup.-1]) produced by long-term experimental thinnings. Five-year survival averaged 2.5% and varied among BAs. Mean survival duration was longer in intermediate BAs (11 to 16 months) than in clearings and high BAs (5 months). The BAs of 7, 14, and 23 [m.sup.2]*[ha.sup.-1] had >2600 5-year-old seedlings*[ha.sup.-1]. In contrast, regeneration was lower in the clearing (666 seedlings*[ha.sup.-1]) and failed completely in the 34[m.sup.2]*[ha.sup.-1] and unthinned treatments. Seedling survival was highest during wet years and lowest during drought years. Many surviving seedlings had no net height growth between years 4 and 5 because of stem browsing. Results indicate that natural regeneration of ponderosa pine is influenced by stand BA, drought, herbivory, and interactions between extreme climatic events. Key words: Pinus ponderosa, thinning, tree seedling establishment, seedling mortality, stand management. Les arbres des forets seches se regenerent souvent en vagues episodiques lorsque des periodes humides coincident avec une production abondante de graines. On connait mal les facteurs responsables du succes ou de l'echec des vagues de regeneration. Nous avons etudie les effets de l'eclaircie des peuplements sur la survie et la croissance de la cohorte de semis de pin ponderosa (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) etablie en 2013 dans le nord de l'Arizona, aux Etats-Unis. Nous avons mesure la survie et la croissance des semis au cours des cinq premieres saisons de croissance apres leur germination en fonction de six classes de surface terriere (0, 7, 14, 23, 34 et 66 (non eclairci)[m.sup.2]*[ha.sup.-1]) provenant d'un dispositif experimental suivi a long terme. Le taux de survie a 5 ans etait en moyenne de 2,5 % et variait selon la surface terriere. La duree de survie moyenne etait plus longue pour les surfaces terrieres intermediaires (11 a 15 mois) que dans les zones coupees a blanc et celles oU la surface terriere etait elevee (5 mois). Les surfaces terrieres de 7, 14 et 23 [m.sup.2]*[ha.sup.-1] avaient plus de 2600 semis-ha-1 ages de 5 ans. En revanche, la regeneration etait plus faible dans les zones coupees a blanc (666 semis*[ha.sup.-1]) et etait completement absente dans le traitement a 34 [m.sup.2]*[ha.sup.-1] et les zones non eclaircies. La survie des semis etait la plus elevee pendant les annees humides et la plus faible pendant les annees de secheresse. La croissance nette en hauteur de nombreux semis survivants a ete nulle entre la quatrieme et la cinquieme annee en raison du broutement. Les resultats indiquent que la regeneration naturelle du pin ponderosa est influencee par la surface terriere du peuplement, la secheresse, l'herbivorisme et les interactions entre les evenements climatiques extremes. [Traduit par la Redaction] Mots-cles: Pinus ponderosa, eclaircie, etablissement des semis, mortalite des semis, amenagement des peuplements., Introduction Many coniferous forests of western North America are experiencing large-scale mortality of mature trees from drought, wildfire, and bark beetle (Dendroctonus ponderosae Hopkins, 1902) attacks (Cohen et al. 2016; [...]

In the latest literature, climate models show that the conditions for pines, spruces, larches, and birches will deteriorate significantly. In Poland, as well as in other European countries, there are already signs of the decline of these species. This review article deals with the symbiotic relationships between fungi and plants, which can hardly be overestimated, using the example of pine trees. These are the oldest known symbiotic relationships, which are of great benefit to both components and can help plants, in particular, survive periods of severe drought and the attack of pathogens on the roots. This article describes symbioses and their causal conditions, as well as the mycorrhizal components of pine trees and their properties; characterizes ectomycorrhizal fungi and their mushroom-forming properties; and provides examples of the cultivation of pure fungal cultures, with particular attention to the specificity of the mycorrhizal structure and its effects on the growth and development of Pinus species. Finally, the role of mycorrhiza in plant protection and pathogen control is described. [ABSTRACT FROM AUTHOR]

Background Black locust (BL, Robinia pseudoacacia) is considered a promising tree species for reforestation due to its great ability to fix nitrogen. However, after two or three coppice-harvesting rotations, the productivity of BL declines. Whether soil microbial communities are affected and how these groups correlate with the nitrogen mineralization process across multi-generation stands remains unclear. Methods We investigated the composition and structure of free-living nitrogen-fixing microorganisms (diazotrophs) by sequencing the marker gene nifH and compared these results to levels of soil nitrogen mineralization in the bulk soil and rhizosphere in black locust plantations on Mount Tai, China. Results The results showed multi-generation BL coppice plantations decreased the total soil nitrogen (N), soil phosphorus (P), soil microbial biomass N (MBN), soil microbial biomass C (MBC), soil nitrification rate (Rn), soil ammonification rate (Ra), and net soil N mineralization rate (Rm), but significantly increased the concentration of soil NH4+-N to maintain sufficient NO3−-N. The dominant species in bulk soil and rhizosphere changed from Rhodopseudomonas (22.62% and 15.76%), unclassified_c_Alphaproteobacteria (22.37% and 29.28%), unclassified_o_Rhizobiales (15.40% and 13.31%), Bradyrhizobium (12.00% and 11.74%) in seedling plantations to Bradyrhizobium (45.95% and 47.86%) and Rhodopseudomonas (43.56% and 41.84%) in coppice plantations, respectively. Mantel test and Redundancy analysis (RDA) revealed that Rn, Ra, and Rm were the most important factors shaping the diazotrophic communities. Conclusions Our results suggest that the multi-generation BL coppice plantation can homogenize soil diazotrophic communities, which is mainly regulated by the available N loss caused by nitrogen mineralization. Strengthening the management technology of coppice plantations will provide more beneficial external consumption. [ABSTRACT FROM AUTHOR]

In ancient times, human beings believed that the sun revolved around the Earth. Copernicus and Galileo, among others, demonstrated that the opposite was true, that the Earth actually revolved around [...]

A better understanding of the response of plant growth to elevational gradients may shed light on how plants respond to environmental variation and on the physiological mechanisms underlying these responses. This study analyzed whole plant growth and physiological and morphological properties of needles in young Pinus koraiensis Sieb. et Zucc. trees at thirteen points along an elevational gradient ranging from 750 to 1350 m above sea level (a.s.l.) at the end of a growing season on Changbai Mountain in northeastern China. Sampling and analyses indicated the following; (1) many needle properties of P. koraiensis varied with forest type along the elevational gradient though some needle properties (e.g., intrinsic water use efficiency, concentration of chlorophyll, and leaf mass per area) did not change with elevation and forest types; (2) growth was significantly influenced by both forest type and elevation and growth of saplings in P. koraiensis and mixed broadleaved forests was greater than that in evergreen forests and increased with elevation in both forest types; (3) in P. koraiensis and mixed broadleaved forests, there were significant correlations between growth properties and light saturation point, leaf water potential, mean within-crown humidity, annual precipitation, cumulative temperature (≥5 °C), within-crown air temperature, and atmospheric pressure; while in evergreen forests, the leaf C, leaf P content, net rate of light saturation in photosynthesis, water content of soil, within-crown humidity, annual precipitation, cumulative temperature (≥5 °C), within-crown air temperature, and total soil P content displayed a significant relationship with plant growth. These results may help illuminate how P. koraiensis responds to environmental variation and evaluate the adaptive potential of Pinus koraiensis to climate change. Data presented here could also contribute to the more accurate estimation of carbon stocks in this area and to refinement of a plant trait database. [ABSTRACT FROM AUTHOR]