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A clear carryover effect of tree-ring formation was not detected based on a pulse-labelling experiment conducted on Juniperus communis in South Germany. The inherent linkage between photosynthesis and the formation of wood is important for the understanding of relationships between tree-ring series and climate/environmental data in dendroclimatology studies. However, it is impossible to reach a mechanistic procedure of tree stem radial growth depending on its carbon balance from a traditional statistical point of view alone. Pulse labelling experiment with stable carbon isotope (13CO2) has provided innovative insights into the fate of recently assimilated carbon in organs and carbon-containing compounds. In this study, we conducted an in situ pulse labelling experiment on 27 July 2016 to examine the response of tree ring and different-aged needles to short-term elevated 13CO2 of a juniper shrub growing on a heathland in South Germany. New and old needles from four expositions were sampled before and after the experiment. A wood segment was taken from the main branch and stable carbon isotope composition (δ13C) was analysed at an intra-annual time scale. Before the experiment, the mean δ13C was − 26.8 ± 0.4‰ (mean ± standard deviation) for both needle ages, while woody tissue showed about 3‰ higher δ13C compared to needles. Substantial enriched 13C was detected in the needles after the experiment. New needles showed significant higher δ13C than the old ones 1–7 days after the experiment. Significant enriched δ13C was detected in the wood from 35 to 61% of the annual tree ring in 2016, indicating that the short-term enrichment of 13C can affect wood formation for a large section. No enhancement in 13C signal appeared in the tree ring of the subsequent year 2017, suggesting the absence of a carryover effect. Wood formation did not reply on the carbohydrates stored even 1 year before and thus tree-ring ecophysiological modelling as well as dendrochronological studies should therefore benefit from such result.

There are important gaps to understand the composition of the fauna associated with macroalgae, such as, how distinct algal morphology and environmental features, like turbulence or circulation patterns, may affect the distribution of them. In this study, macroalgae and associated fauna samples were undertaken between 4 and 12-m depth at three sites within the Admiralty Bay, King George Island, during the austral summer of 2000/2001. Previous physical oceanography data from the bay showed that each of these sites featured different circulation regimes. Differences and similarities in composition and density of the fauna associated with five species of macroalgae with different morphologies were analyzed: foliose (Monostroma hariotii and Palmaria decipiens); mixed (Myriogramme mangini); and branched (Desmarestia menziesii and Phaeurus antarcticus). Results showed differences in density, dominance of taxa, and richness among taxonomic groups of the associated fauna were related to algal morphology and circulation patterns. The dominance of epifaunal groups among macroalgae (e.g., D. menziesii, M. hariotii, and M. mangini) showed an adaptive response to different water flow settings within the bay, particularly in the community under the most intense flow. Further studies on associated fauna, should consider other environmental physical features and take our study like baseline to understand how major processes (e.g., climate change, seawater properties and circulation) may affect the communities, especially in more vulnerable shallow water zones.

Climate change is expected to be heterogeneous across the world, with high impacts on the Himalayan ecosystems. There is a need to precisely document cambial phenology and wood formation in these regions to better understand climate-growth relationships and how trees face a warming climate. This study describes the dynamics of cambial phenology in pindrow fir (Abies pindrow) along its altitudinal gradient in the Himalaya. The stages of xylem phenology, and the duration and rate of wood formation were assessed from anatomical observations during the growing season from samples collected weekly from three sites at various altitudes (2392–2965 m a.s.l.) over two years. There were significant differences in the duration and rate of cell formation along the altitudinal gradient, which decreased at increasing altitudes. The growing season duration decreased by 5.2 and 3.7 days every 100 m of increase in altitude in 2014 and 2015, respectively, while the rate of cell formation decreased from 0.38 and 0.44 cells /day to 0.29 and 0.34 cells/day in 2014 and 2015, respectively. Cell production decreased from 63.3 and 67.0 cells to 38.3 and 45.2 cells with a decrease of 4.3 and 3.8 cells per 100 m increase in altitude in 2014 and 2015, respectively. The higher precipitation in 2015 increased the growth rate and resulted in a higher xylem production. Our findings give new insights into the dynamics of cambial phenology and help in better understanding of the potential impacts of climate change on tree growth and forest productivity of Himalayan forests.

Climate change is altering phenology; however, the magnitude of this change varies among taxa. Compared with phenological mismatch between plants and herbivores, synchronization due to climate has been less explored, despite its potential implications for trophic interactions. The earlier budburst induced by defoliation is a phenological strategy for plants against herbivores. Here, we tested whether warming can counteract defoliation-induced mismatch by increasing herbivore-plant phenological synchrony. We compared the larval phenology of spruce budworm and budburst in balsam fir, black spruce, and white spruce saplings subjected to defoliation in a controlled environment at temperatures of 12, 17, and 22°C. Budburst in defoliated saplings occurred 6-24 days earlier than in the controls, thus mismatching needle development from larval feeding. This mismatch decreased to only 3-7 days, however, when temperatures warmed by 5 and 10°C, leading to a resynchronization of the host with spruce budworm larvae. The increasing synchrony under warming counteracts the defoliation-induced mismatch, disrupting trophic interactions and energy flow between forest ecosystem and insect populations. Our results suggest that the predicted warming may improve food quality and provide better growth conditions for larval development, thus promoting longer or more intense insect outbreaks in the future.

19 pages, 8 figures,5 tables, supplemental Information https://doi.org/10.7717/peerj.12032.-- Data Availability: The following information was supplied regarding data availability: The raw measurements are available in the Supplemental File, The ecological physiology of anthozoans, as well as their resistance to stressors, are strongly influenced by environmental factors and the availability of resources. The energy budget of anthozoans can vary seasonally in order to find an equilibrium between the available resources and respiration, polyp activity, growth, and reproduction processes. The variation in the biochemical composition of the animal tissues in these organisms results from a combination of the productivity processes of the water column coupled with the reproductive effort and potential starvation periods of the anthozoans. Here, the seasonal variation in the polyp activity of a slow-growing passive suspension feeder, the octocoral Alcyonium acaule, as well as their carbohydrate, protein and lipid contents, was investigated in a warm temperate environment using in-situ observations and biochemical analyses. Polyp activity exhibited a significant variability that was moderately dependent on season, while an aestivation phenomenon in A. acaule (i.e., a resting period in which the anthozoan is not capable of any polyp activity) during the warmer months is clearly observed. Carbohydrate concentrations in the coral species showed a significant increase in the late winter and spring seasons, and the lipid content increased during the spring. A higher abundance of lipids and carbohydrates coincided with a higher primary productivity in the water column, as well as with the octocoral reproduction period. In late autumn, there was a depletion of these biomolecules, with protein levels exhibiting great variability across sampling times. Complex alterations driven by climate change could affect the energy fluxes that depend on the dead or alive particles that are intercepted by marine animal forests. The obtained findings show a food shortage in late summer and autumn of the benthic suspension feeder A. acaule through the integrative descriptors of the ecophysiology of these anthozoans. This research contributes to the knowledge of energy storage capabilities in benthic suspension feeders in general, highlighting the importance of understanding the limits of resistance to starvation periods through these indicators, This research was funded by the Spanish project MEDGORG, CICYT (REN2000-0633- C03-01/MAR), With the institutional support of the ‘Severo OchoaCentre of Excellence’ accreditation (CEX2019-000928-S)

Soil influences the growth of trees and the characteristics of the wood, but could this influence change during the ontogeny of trees? To answer this question, we analyzed the wood anatomy of 9-year-old trees and 2-year-old saplings of Enterolobium contortisiliquum, known as “tamboril”, growing in eutrophic and oligotrophic soil in the Brazilian Cerrado, and assessed the effect of age on plant–soil relationship. Sapwood samples were collected from the main stem, anatomical sections were prepared in the lab, and 12 anatomical wood traits were measured. Individuals in eutrophic soil had greater stem diameter and height than those in oligotrophic soil. Trees in eutrophic soil had vessel-associated parenchyma cells with abundant storage compounds. Fibers walls were 47% thicker and intervessel pits diameter were 14% larger in trees of eutrophic soil. A greater proportion of solitary vessels (74%) was observed in trees rather than in saplings (50%). The secondary xylem of trees was mainly formed by fibers (63%) whereas in saplings it was mainly formed by storage tissue (64%). Our study provides evidence that the influence of soil conditions on tree growth reflects variations in wood anatomical features. No significant response to soil type was observed in saplings, thus demonstrating that the relationship between soil type and wood growth is mediated by tree age. These findings help to develop reliable reforestation strategies in tropical ecosystems characterized by different levels of soil fertility.

Questions: Elevational treelines are expected to shift upwards in response to warming climate. However, worldwide upward shifts of treelines are inconsistent because local scale factors can affect the response to temperature. In this study, we explore the hypothesis that in the Apennines, where the current altitudinal treeline position is largely depressed because of past human activity, shrubs act as nurse plants promoting the upward migration of Fagus sylvatica. Location: A 500–km-long latitudinal gradient in the Apennines, Italy. Methods: We selected, along this gradient, nine treeline sites with different elevations, rock substrates, and physiognomic types including Juniperus communis, Pinus mugo, Vaccinium myrtillus shrublands, and grasslands. Here, in 68 transects we collected and analysed spatially fine-scale distribution data of F. sylvatica individuals in relation to both their age and their position, associated or not with shrubs. Results: Fagus sylvatica regeneration is rare in open secondary grasslands at 1,600–2,100 m a.s.l., highlighting a bottleneck in the regeneration phase of this species. On the contrary, we systematically observed a strong association between shrubs and F. sylvatica individuals. Compared with the adjacent grassland, F. sylvatica regeneration was 58.3 times higher under Pinus mugo, 131.5 timeshigher under Juniperus communis and 102.4 times higher under Vaccinium myrtillus. The age structure of F. sylvatica population indicates that, in the last 50 years, recruitment under shrubs is continuous, while in grassland it is episodic. Conclusions: Above the current treeline of the Apennines, F. sylvatica individuals develop only in the presence of shrubs, which act as nurse species. Shrubs are a necessary condition for F. sylvatica re-colonization of the high-altitude open areas affected, in the last centuries, by intense human land use.

Warming-induced drought stress leads to convergent and negative growth responses to temperature between sympatric tree species, implying an increasing interspecific competition for soil moisture. In mixed forests, sympatric tree species avoid competition by partitioning their niches according to available environment resources. We raise the hypothesis that climate warming leads to a convergence in growth responses to climate, thus increasing the competition among sympatric species in drought-prone forests. In this study, we selected a mixed forest located at ca. 3600 m a.s.l in the Baima Snow Mountains, an inner dry valley of the southeastern Tibetan Plateau. We measured width of the tree rings produced during 1910–2016 in 60 trees belonging to three sympatric species: Abies georgei, Picea likiangensis, and Betula delavayi. We analyzed the changes in radial growth and their responses to climate. We detected shifts in the responses to climate after the 1990s. The radial growth of all species was positively correlated with precipitation from 1964 to 1990, but negatively correlated with March–June temperature from 1991 to 2016. Compared to the period 1964–1990, convergent and negative growth responses to warmer temperatures in the period 1991–2016 probably reflect less available soil moisture for growing in this mixed forest. We conclude that climate warming will affect the niches of sympatric species in mixed forests subjected to seasonal drought, thus increasing competition and altering structure and composition of the stands in dry regions.

Key messageThe intra-annual variability in stem size of marginal beech population from south-eastern distribution range of beech in Poland is higher within than between populations.AbstractOne of the key issues of the distribution of tree species is their ability to track environmental changes. European beech (Fagus sylvaticaL.) is a species highly sensitive to extreme climatic events, because of its high phenotypic plasticity. In this study, we aim to determine the variability in stem size between and within marginal beech populations. Marginal populations of beech growing under uniform environmental conditions of provenance trial offer unique opportunity to detect adaptive differentiations driven by natural selection. In this work, we studied stem size variation recorded by automatic band dendrometers in four beech marginal populations growing in a common garden in the south-eastern distribution range of beech in Poland over the period 2016–2018. Strong climatic effects and weak provenance differences in seasonal stem size variation were observed. The provenances exhibited similar climate-related seasonal stem circumference variation. A high within-provenance variation was confirmed. Temperature of spring as well as temperature and precipitation of autumn were detected as key climatic parameters mostly for onset and end of stem size variation. Maximum stem size was mostly affected by the later end of its variation, which positively affected its duration. Climatic distance between beech provenances and provenance trial had a negligible effect on the variability in seasonal stem size variation between provenances. The evidence of weak inter-provenance and high intra-provenance variation in stem size changes observed in the south-eastern distribution range indicates that an individual-based approach could be a suitable strategy, when selecting for phenotypic plasticity.

There is evidence that the ongoing climate change is happening through nighttime rather than daytime warming. How such a daily-asymmetric warming modifies plant phenology is still unclear. We investigated the effects of asymmetric warming on bud break by daily monitoring seedlings belonging to 26 black spruce [Picea mariana (Mill.) BSP.] and 15 balsam fir [Abies balsamea (L.) Mill.] provenances from the native range in Canada. Seedlings were subjected to either daytime or nighttime warming in three growth chambers at temperatures ranging between 10 and 24 °C. On average, a warming of 4 °C advanced the timings of bud break in both species by 2.4 days, with the later phases being more sensitive to the treatment. Bud break of both species responded more strongly to daytime warming, with the bud break occurred 1.2 and 3.2 days earlier under daytime than nighttime warming in black spruce and balsam fir, respectively. A marked ecotypic differentiation was only observed in black spruce that originated from provenances distributed broadly across Canada, with seedlings from the warmest provenance completing bud break 8.3 days later than those from the coldest one. However, no significant effect of provenance was observed for balsam fir, the narrowly distributed species. Overall, the above results suggest that a higher temporal resolution such as temperatures during daytime and nighttime, and higher spatial resolution should be taken into account to improve the accuracy of phenological model predictions under global change scenarios. Phenological models based on daily average temperature should take into account the diverging impacts of asymmetric warming on plant phenology. Our findings may indicate that the influence of warming on plant phenology may be less dramatic than expected.

A number of studies have suggested that growing season length determines carbon sequestration of forest ecosystems. Given the possibility that drought-induced growth decline will be caused by a prolonged growing season under a warming climate, we investigated the effect of growth rate and duration of xylem production on annual wood biomass in drought-prone environments. We analyzed the intra-annual dynamics of wood formation in Qilian junipers (Juniperus przewalskii) from the semi-arid north-eastern Tibetan Plateau, China (2009–2014) and in ponderosa pine (Pinus ponderosa) from the hyperarid Mojave Desert in Nevada, USA (2015–2016). Most variability in the number of xylem cells (Ncell) was related to growth rate (rm) rather than duration of cell production (Dcell). At the Tibetan sites, 69.9% and 54.7% of variability in Ncell was attributable to rm for the lower and upper treeline, respectively. Within the Mojave Desert site, 53.9% of the variability in Ncell was related to rm. The growth rate in the Tibetan Plateau forest is affected by minimum temperature and precipitation. Thus, rm is a primary control on wood biomass in conifer species of semi-arid forests. Under warmer and drier conditions, a longer growing season will not benefit xylem formation of conifers, and in turn warming-induced drought could limit carbon sequestration by reducing the rate of cell production.

Late spring frost plays a major role in the structure and function of forest ecosystems with potential consequences on species distribution at both local and regional scales. Paradoxically, in a warmer world the incidence and impact of frost is increasing because of earlier leaf unfolding and flowering as a response to warmer temperatures. In this regard, European Beech (Fagus sylvatica L.), a native tree species widely distributed in European forests, is considered particularly sensitive to changes in spring temperature regimes associated with climate change and thus especially subject to the risk of frost damage. Although several studies concerning F. sylvatica frost damage have been conducted in northern and central Europe, no extensive studies are available for the southern part of its range, i.e. central and southern Italy as well as Greece. In this paper the effect of a late spring frost occurring at the end of April 2016 is extensively documented with high spatial detail all along the Apennine Chain through satellite image data. Three different remote-sensing greenness indexes, namely the normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and the greenness index (GI) derived from Landsat-8 satellite images acquired from May to July in the years 2014, 2015, and 2016 at a spatial resolution of 30 m, were used to gauge the spatial response of common beech forests to this late frost event with relation to latitude, altitude and slope exposure. Frost damage was evaluated as a difference (Δ) of NDVI, GI and EVI between the mean of years 2014 and 2015 (i.e. MRY, mean of reference years), and 2016 (i.e. FEY, frost reference year). The three satellite remote-sensing indexes were efficient at detecting leaf damage with detailed spatial resolution and proved consistent with one another. The greatest damage occurred in the middle altitudinal range between 1500 and 1700 m a.s.l. with a decreasing trend toward both lower and higher elevations due to warmer temperatures below, and delayed phenology above. Exposure also influenced frost injury, with south-facing slopes of the mountain more damaged than the north. This difference was due to earlier spring leaf phenology of southern beech trees in response to a greater heat sum in the warm weeks preceding. Less damage in the northern Apennines is consistent with the spatial extent of minimum freezing temperatures. To sum up, frost damage is strongly related to site-specific conditions, i.e. on the one hand to minimum temperatures, and on the other to the phenological stage of the trees involving both altitude and exposure. Hence focusing on detailed sub-regional studies can be helpful for predicting future consequences of climate change on forests.

In short-rotation coppice, shoots grow at high density and compete for limiting resources with their neighbours. Interactions among shoots translate into individual size differences due to resource apportionment. In the present study we compared shoot dynamics of six hybrid poplars and three wild river genotypes of Populus nigra under the first three-year cycle of multi-stem short-rotation coppice. We investigated changes over time in diameter frequency distribution, mortality and biomass partitioning according to crown classes of the shoots. Unimodal shoot diameter distributions during rotation modelled by a two-parameter Weibull probability density distribution show that the values of the α scale parameter are higher in hybrid genotypes compared to wild black poplars (α ≥ 2.0 and α ≤ 2.0, respectively) in all three years. The values of the β shape parameter mostly decrease over time in hybrid genotypes and increase in wild black poplars in the narrow range from 1.42 to 2.38 and from 1.47 to 2.03, respectively. With regard to biomass partitioning among shoot crown classes, differences in size attributes are more pronounced in hybrids than native black poplar genotypes. In hybrid genotypes, 83.7% of the biomass is allocated to dominant shoots, while wild black poplars share 71.6% of the biomass in the dominant and 24.8% in the intermediate shoots. This disproportional biomass allocation among crown classes of hybrid compared to native genotypes could be related to their different origin of selection.

Climate scenarios for Slovenia suggest an increase in the mean annual temperature by 2 °C over the next six decades, associated with changes in the seasonal distribution of precipitation. European beech is an ecologically and economically important forest species in Europe, so it is important to understand the influence of changing conditions on its phenology and productivity for the upcoming years. We hypothesise that the ongoing warming and reduction in precipitation during the growing season will shorten the period of xylem development, thus limiting beech growth in the next decades. Xylem formation was monitored weekly from 2008 to 2016 at two sites in Slovenia. Onset and cessation of cell enlargement and secondary wall formation, as well as xylem growth, are used to evaluate climate-growth relationships by means of partial least squares regression and to predict xylem formation phenology and annual xylem increments under climate change scenarios. A positive correlation of spring phenological phases with March–May temperatures is found. In contrast, autumn phenological phases show a negative correlation with August and September temperatures, while high temperatures at the beginning of the year delay growth cessation. According to the selected climate change scenarios, phenological phases may advance by 2 days decade-1 in spring and delay by 1.5 days decade-1 in autumn. The duration of the growing season may increase by 20 days over the next six decades, resulting in 38 to 83% wider xylem increments. The growth of beech is expected to increase under a warming climate in the sites characterised by abundant water availability.

Water temperature directly affects life cycles, reproductive periods, and metabolism of organisms living the oceans, especially in the surface zones. Due to the ocean warming, changes in water stratification and primary productivity are affecting trophic chains in sensitive world areas, such as the Mediterranean Sea. Benthic and pelagic cnidarians exhibit complex responses to climatic conditions. For example, the structure and phenology of the Mediterranean hydrozoan community displayed marked changes in species composition, bathymetric distribution, and reproductive timing over the last decades. The regional species pool remained stable in terms of species numbers but not in terms of species identity. When the Scyphozoa group is considered, we observe that Pelagia noctiluca (among the most abundant jellyfish in the Mediterranean Sea and eastern Atlantic waters) has increasingly frequent massive outbreaks associated to warmer winters. Variations in metabolic activities, such as respiration and excretion, are strongly temperature-dependent, with direct increment of energetic costs with jellyfish size and temperature, leading to growth rate reduction. Water temperature affects sexual reproduction through changes in the energy storage and gonad development cycles. Anthozoan life cycles depend also on primary productivity and temperature: gonadal production and spawning are tightly related in shallow populations (0–30 m depth) with the spring-summer temperature trends and autumn food availability. Overall, the energy transferred from the mother colonies to the offspring may decrease, negatively affecting their potential to settle, metamorphose and feed during the first months of their lives, eventually impairing the dominance of long-living cnidarian suspension feeders in shallow benthic habitats. In this review, we describe the already ongoing effects of sea warming on several features of cnidarian reproduction, trying to elucidate how reproductive traits and potential dispersion will be affected by the cascade effects of increasing temperature in the Mediterranean Sea.

The occurrence of endocrine disrupting chemicals (EDCs) has been determined in two widely consumed fish species from Persian Gulf i.e., Epinephelus coioides and Platycephalus indicus by applying a validated analytical for the simultaneous detection of fourteen EDCs. The concentrations of all detected EDCs were greater in the liver than in the muscle (except for bisphenol A in P. indicus), suggesting a prolonged exposure of the fishes to these pollutants in the Persian Gulf. Specifically, the results showed that di (2-ethylhexyl) phthalate (DEHP) was the compound detected most frequently and at the highest concentration in both species. DEHP levels in ranged from 6.68 to 297.48 μg g-dw−1 and from 13.32 to 350.52 μg g-dw−1, in muscle and in liver, respectively. A risk assessment study was conducted, and demonstrated that consuming two fish based- meals per week may result in a moderate risk especially for vulnerable population groups.

Ecological profiling of non-native species is essential to predict their dispersal and invasiveness potential across different areas of the world. Cassiopea is a monophyletic taxonomic group of scyphozoan mixotrophic jellyfish including C. andromeda, a recent colonizer of sheltered, shallow-water habitats of the Mediterranean Sea, such as harbors and other light-limited, eutrophic coastal habitats. To assess the ecophysiological plasticity of Cassiopea jellyfish and their potential to spread across the Mare Nostrum by secondary introductions, we investigated rapid photosynthetic responses of jellyfish to irradiance transitions—from reduced to increased irradiance conditions (as paradigm of transition from harbors to coastal, meso/oligotrophic habitats). Laboratory incubation experiments were carried out to compare oxygen fluxes and photobiological variables in Cassiopea sp. immature specimens pre-acclimated to low irradiance (PAR = 200 μmol photons m−2 s−1) and specimens rapidly exposed to higher irradiance levels (PAR = 500 μmol photons m−2 s−1). Comparable photosynthetic potential and high photosynthetic rates were measured at both irradiance values, as also shown by the rapid light curves. No significant differences were observed in terms of symbiont abundance between control and treated specimens. However, jellyfish kept at the low irradiance showed a higher content in chlorophyll a and c (0.76±0.51SD vs 0.46±0.13SD mg g-1 AFDW) and a higher Ci (amount of chlorophyll per cell) compared to jellyfish exposed to higher irradiance levels. The ratio between gross photosynthesis and respiration (P:R) was >1, indicating a significant input from the autotrophic metabolism. Cassiopea sp. specimens showed high photosynthetic performances, at both low and high irradiance, demonstrating high potential to adapt to sudden changes in light exposure. Such photosynthetic plasticity, combined with Cassiopea eurythermal tolerance and mixotrophic behavior, jointly suggest the upside-down jellyfish as a potentially successful invader in the scenario of a warming Mediterranean Sea.

Poplar short rotation coppice (SRC) plantations have great potential for supplying environmentally friendly bio-based industries. However, little research has focussed on the linkages between SRC management regimes and the consumption of water for biomass production in the Mediterranean environment. Therefore, we compared six hybrid clones and four native black poplar genotypes with an aim to examine how two different lengthening periods (3 vs. 5 years) of single-stem rotation affected growth performance in the following three years of multi-stem rotation coppice. To achieve this goal, we assessed the aboveground dry biomass production and variation in water use efficiency (WUE) of the genotypes annually. A longer single-stem rotation increased biomass productivity and WUE in the multi-stem rotation of the native black poplar, rather than that of the hybrid genotypes. In contrast, biomass and WUE performances did not diverge between the native and hybrid genotypes under the shorter single-stem phase. These findings underline the importance of lengthening the rotation of single-stem SRC plantations in hot and dry Mediterranean climates. Native black poplar genotypes managed in SRC should be strongly considered as environmentally compatible genetic resources both in protected areas and in areas where water supply constrains biomass production.

12 pages, 9 figures, 1 table, Alcyonium coralloides is an epibiotic soft coral overgrowing living colonies of Mediterranean gorgonians. The main features of the sexual reproductive cycle of this soft coral species are described and quantified for the first time, in a population found at 18 to 22 m depth off the Medes Islands (NW Mediterranean). A. coralloides is a gonochoric internal brooder. The sexual cycle showed a single reproductive event per year. Gametogenesis took 5 to 6 mo, which is the shortest known gametogenesis in littoral octocorals (especially for oogenesis). The maximum mean ± SD diameter was 365 ± 86 µm for spermatic cysts and 632 ± 125 µm for mature oocytes. Sperm was released in spring (late May). Average male and female fecundity in this last phase of the cycle was 15 ± 9 spermatic cysts and 7 ± 4 oocytes per polyp, respectively. Larvae of about 1000 µm in length were observed in the gastrovascular cavities of female colonies in May, before they were released in June. We suggest that the remarkable short gametogenesis and timing shown by A. coralloides is an adaptation to optimize the colonization of its host (in this case the gorgonian octocoral Paramuricea clavata). We conclude that A. coralloides larvae could be ready to settle in early summer when the host P. clavata is probably more vulnerable as a result of its own reproductive cycle coming to an end, We are especially grateful to J. Pascual for environmental data collection, E. Rodriguez from the American Museum of Natural History, NY, for reviewing the text and the reviewers who critically read the manuscript and helped to improve the document with their comments. This work was partially funded by the program LIFE+INDEMARES (LIFE07 NAT/E/000732- ‘Inventariación y designación de la red Natura 2000 en áreas marinas del estado español’). Partial support was provided to T.M. by a JAEDoc (Consejo Superior de Investigaciones Científicas, SPAIN) grant; S.R. was funded by a Ramón y Cajal contract (RYC-2007-01327)

Invasive species are one of the biggest threats to coastal areas. Jellyfish, when found in aquaculture systems, may cause major economic damage; they are already present in many aquaculture facilities in the Mediterranean, Yellow Sea, and Bohai Sea. Herein, for the first time, we describe the occurrence of the upside-down jellyfish (genus Cassiopea) in shrimp (Litopenaeus vannamei) farms. The observed specimens were collected on the equatorial Southwestern Atlantic coast (Northeast Brazil) for identification by genetic sequence data (COI). The results indicate that the jellyfish in aquaculture systems are similar in terms of morphology and genetics to those found in natural environments in Bermuda, Egypt, Hawaii, Florida, and elsewhere in Brazil (Rio de Janeiro) and are related to specimens originally inhabiting the Red Sea (Cassiopea andromeda). In addition, we report the northward expansion of C. andromeda along the Brazilian equatorial margin. Only female jellyfish were observed, which suggests that the maintenance and spread of the non-indigenous population occur by asexual reproduction. The high abundance and presence of juvenile and adult animals may have major economic impacts on a high-value industry, given the potential of the population to spread to shrimp farms located in tropical mangroves.

International audience; Defoliation can enhance tree water status by reducing canopy transpiration under drought. During long-lasting insect outbreaks however, this effect can be transient as reduced foliage affects not only transpiration but also the entire soil-plant-atmosphere continuum. In this study, we investigated the effects of defoliation and vapor pressure deficit (VPD) on plant and soil water status in balsam fir and black spruce defoliated by spruce budworm, Choristoneura fumiferana (Clemens). We sampled 48 fir trees and 36 spruce trees subjected to differing severities of defoliation. In May–September 2014 and 2015, we monitored the relative shoot water content (RWC) and soil volumetric water content (VWC), and midday shoot water potential (Ψmd, only in 2015). We applied linear mixed models (LMMs) to assess changes in RWC, Ψmd, and VWC to defoliation and VPD and we ran structural equation models (SEM) to determine the causal relationships between the measured variables in relation to defoliation and VPD. In LMMs models, defoliation and VPD, as individual factors, reduced Ψmd in both balsam fir and pooled species models but did not affect RWC. Defoliation alone increased VWC in balsam fir and in pooled models. We observed no interaction between VPD and defoliation on tree water status, but significant effect on VWC (in balsam fir and pooled models), indicating that both factors had independent and additive effects on plants but not on soil. However, in SEM models, RWC was negatively correlated to defoliation, suggesting a hydraulic safety margin. Under conditions of multiple-years of natural defoliation during a spruce budworm outbreak, the decrease in Ψmd reflects the amount of internal water capacitance that could be caused by both a lower Ψmd due to larval feeding and a negative feedback between defoliation and xylem vulnerability.

Made available in DSpace on 2020-12-12T02:21:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-09-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Intraspecific studies with populations replicated in different sites allow the effects of genotype and environment on wood features and plant growth to be distinguished. Based on climate change predictions, this distinction is important for establishing future patterns in the distribution of tree species. We quantified the effects of genotype and environment on wood features and growth of 30-year-old Balfourodendron riedelianum trees. We used three provenances planted in two common garden experiments with difference in precipitation and temperature. We applied linear models to estimate the variability in wood and growth features and transfer functions to evaluate the responses of these features to temperature, precipitation, and the standardized precipitation evapotranspiration index (SPEI). Our results showed that genotype had an effect on vessels and rays, where narrower vessels with thinner walls and larger intervessel pits, and shorter, narrower and more numerous rays were observed in provenances from drier sites. We also observed the effect of the environment on wood features and growth. Trees growing in the wetter site were taller and larger, and they had wider vessels with thicker walls and lower ray density. Transfer functions indicated that an increase in temperature results in larger vessels with thicker walls, taller and denser rays, shorter and narrower fibers with thinner walls, and lower wood density. From a functional perspective, these features make trees growing in warmer environments more prone to drought-induced embolisms and more vulnerable to mechanical damage and pathogen attacks. Tree growth varied with precipitation and SPEI, being negatively affected in the drier site. Overall, we demonstrated that both genotype and environment affect wood features, while tree growth is mainly influenced by the environment. Plastic responses in hydraulic characteristics could represent important functional traits to mitigate the consequences of ongoing climate change on the growth and survival of the species within its natural range. Laboratório de Anatomia da Madeira Departamento de Ciência Florestal Solos e Ambiente Faculdade de Ciências Agronômicas Universidade Estadual Paulista (UNESP), Câmpus de Botucatu Département des Sciences Fondamentales Université du Quebec à Chicoutimi Instituto Florestal Laboratório de Anatomia da Madeira Departamento de Ciência Florestal Solos e Ambiente Faculdade de Ciências Agronômicas Universidade Estadual Paulista (UNESP), Câmpus de Botucatu FAPESP: 2015/14954-1

Cassiopea jellyfish have successfully invaded several marine ecosystems worldwide. We investigated if Cassiopea andromeda grows larger (umbrella size) and if their populations are more stable in shrimp farms than in mangroves in the Brazilian coast. Our results show that jellyfish abundance is higher in the shrimp farm during the rainy season and in the mangrove during dry season. The population is stable during both seasons in the shrimp farm, but unstable in the mangroves, as jellyfish are absent during rainy season. Shrimp farm-associated jellyfish are three times larger than those in the mangroves, regardless of season. We recorded the largest (49.2 cm of umbrella diameter) ever C. andromeda individual in the shrimp farm. Unlike the mangroves, the shrimp farm provides environmental intra-annual stability that promotes jellyfish growth and population persistence. Therefore, C. andromeda populations can be seasonally dynamic and artificial environments such as aquaculture facilities may facilitate the invasion process.

17-a-ethinylestradiol (EE2) belongs to the increasing list of Endocrine Disruptors Chemicals (EDCs), able to interfere with the endocrine system in both vertebrates and invertebrates. Regardless of its great dispersion in the environment, to date there is still little knowledge about its action mechanisms and harmful effects in invertebrates. To better evaluate its potential role in invertebrates, we used the model system Drosophila melanogaster, an insect in which the hormonal response has been widely described. The effects of EE2 in D.melanogaster adults have been evaluated by using life traits as well as molecular endpoints. It was found that EE2 significantly decreases survival and fertility in both sexes, with a higher effect in female flies, as well as affects the expression of the Ecdysone Receptor (EcR), Estrogen Related Receptor (ERR), Yolk protein2 (Yp2) and yolkless (yl) genes. In conclusion, our results suggest that EE2 treatment may have potential toxic and endocrine effects on Drosophila melanogaster adults of both sexes. In particular, our data provide an indication that, after EE2 treatment, two of the genes involved in the vitellogenesis process (yl and Yp2) are transcribed in adult males where are mostly silent, and suggest future studies forward their use as potential molecular markers to EDCs exposure in Drosophila male.

13 pages, 5 figures, 2 tables, supplementary information https://doi.org/10.1038/s41598-018-30474-x, Jellyfish populations apparently have increased in some places around the world and human problems with them also have increased. However, effects of jellyfish outbreaks in the ecosystems remain poorly understood and little or no information is available on their dietary preferences - in relation to the seasonal shifts of prey abundance - and on the potential variability of their impact on marine food webs. The mauve stinger Pelagia noctiluca (Forsskål, 1775) is by far the most common outbreak-forming scyphozoan jellyfish in the Western Mediterranean. By use of a combination of stomach contents, stable isotope (SI) and fatty acid (FA) analyses, we tested the hypothesis that changes in the seasonal dietary sources of P. noctiluca parallel changes in the FA and SI composition. Stomach content and biomarker analyses suggested that P. noctiluca is not a selective predator, cyclically shifting between carnivory and omnivory depending on the seasonality of accessible prey. The combination of SI and FA analyses highlighted the importance of microzooplankton as prey. Specific FA biomarkers showed that the diet of P. noctiluca changed seasonally depending on the availability of living plankton or suspended detritus. This study also revealed significant biochemical differences between jellyfish somatic and gonadal tissues, with total fatty acid concentration in the gonads up to ten times higher than in the somatic tissues, This work has received funding from the European Union’s projects MED-JELLYRISK (grant n. I-A/1.3/098 - ENPI CBCMED programme), VECTORS (Vectors of Change in Oceans and Seas Marine Life, Impact on Economic Sectors, grant n. 266445, FP7th programme) and CERES (Climate Change and European Aquatic Resources, grant n. 678193, Horizon 2020 programme)

Octocorals represent an important group in reef communities throughout the tropical seas and, like scleractinian corals, they can be found in symbiosis with the dinoflagellate Symbiodinium. However, while there is extensive research on this symbiosis and its benefits in scleractinians, research on octocorals has focused so far mainly on the host without addressing their symbiosis. Here, we characterized and compared the photophysiological features of nine Caribbean octocoral species with different colony morphologies (sea fan, plumes, whips and rods) and related key morphological features with their respective symbiont photobiology. Colony features (branch shape and thickness), as well as micromorphological features (polyp size, density), were found to be significantly correlated with symbiont performance. Sea fans and plumes, with thinner branches and smaller polyps, favor higher metabolic rates, compared to sea rods with thicker branches and larger polyps. Daily integrated photosynthesis to respiration ratios > 1 indicated that the autotrophic contribution to organisms’ energy demands was important in all species, but especially in sea whips. This information represents an important step towards a better understanding of octocoral physiology and its relationship to host morphology, and might also explain to some extent species distribution and susceptibility to environmental stress.

PREMISE OF THE STUDY: Most dendroecological studies focus on dominant trees, but little is known about the growing season of trees belonging to different size classes and their sensitivity to biotic factors. The objective of this study was to compare the dynamics of xylem formation between dominant and suppressed trees of Abies fabri of similar age growing in the Gongga Mountains, southeastern Tibetan Plateau, and to identify the association between xylem growth and climate. METHODS: The timing and duration of xylogenesis in histological sections were investigated weekly during the 2013-2015 growing seasons. KEY RESULTS: Our investigation found that timing and duration of xylogenesis varied with canopy position and its associated tree size. Xylogenesis started 6-14 days earlier, and ended 5-11 days later in dominant trees than in suppressed trees, resulting in a significantly longer growing season. Dominant trees also exhibited higher temperature sensitivity of tracheid production rate than suppressed trees. CONCLUSIONS: The observed differences in xylogenesis among trees suggested that competition affects tree growth by reducing the growing period in suppressed trees. Representative climate-growth relationships should involve trees of all size classes when evaluating the effects of the environment on forest dynamics.

Drought is the primary limiting factor for tree growth in arid and semi-arid regions, where it can greatly influence xylem anatomical traits and induce multiple responses to wood development. However, the mechanisms driving xylogenesis and intra-annual density fluctuations (IADFs), as well as the seasonal dynamics of wood development in water-limited environments, are still unclear. In this study, we assessed the kinetics of xylem development weekly in Chinese pine (Pinus tabuliformis) and Qinghai spruce (Picea crassifolia), at two altitudes in the Helan Mountains, semi-arid China. Results indicate that summer drought in June inhibited cambial division and reduced xylogenesis, resulting in only 40% of the xylem developing before August. The onset of abundant precipitation in mid-July reactivated radial growth. This second growth extended the growing season by one month and partly compensated for the negative effect of the drought on growth. E-type IADF were characterized by narrow cells with thick walls, formed during July and early August. The duration of cell enlargement explained 57% of variance in tracheid diameter, showing that it played an important role in determining cell size. In contrast, changes in the cell wall thickness were mainly driven by the rate of secondary wall thickening, which explained 65% of the variance. This study reveals the potential mechanisms for xylem development and E-IADF formation under summer drought in semi-arid China, provides evidence for the plasticity and resistance of Chinese pine and Qinghai spruce under varying environmental conditions, and contributes to our understanding of likely future trends in forest productivity under climate changes.

The Himalayas are experiencing dramatic warming and drought events, which occur at a faster rate than the global average. How will the high-elevation ecosystems cope with such changing conditions? This study aims to combine cambial phenology with quantitative wood anatomy to understand how the growth dynamics affect the trade-off between safety and efficiency of water transport in the Himalayan forests. We investigated the timing of xylogenesis and its relationship with hydraulic wood anatomical traits in Himalayan birch (Betula utilis D. Don) at two altitudes in the central Himalayas. Xylogenesis was monitored weekly from April to September 2014 by collecting microcores. We measured vessel area on histological sections, calculated the hydraulic diameter, and assessed the effects of climate on xylem production rate. Xylogenesis occurred from June to September in both study sites. Moisture availability influenced positively xylem growth besides thermal conditions. The onset and duration of vessel enlargement were correlated with the hydraulic diameter. Trees with earlier onsets and longer durations of vessel enlargement exhibited larger hydraulic diameters. The close relationship between cambial phenology and hydraulic diameter suggests that earlier growth resumption induced by climate changes may result in larger vessels, which are more efficient in water transport, but vulnerable to drought-induced cavitation. The ongoing warming and drying climate conditions may menace the survival of birch forest in the central Himalayas.

The peculiar shallow-water reefs of the Tropical Southwestern Atlantic Ocean have thrived in conditions considered suboptimal (e.g., moderate turbidity, higher level of nutrients, and resuspension of sediments) under the optics of classical coral reefs. Recently, these marginal reefs have been hypothesized to provide climate-change refugia from natural and anthropogenic impacts; yet with little empirical evidence. Therefore, in this article we discuss the known effects of multiple pressures on the Brazilian reefs. A wide evaluation of the peer reviewed literature reported that bleaching events affected 26 species of scleractinians, hydrocorals, octocorals, and zoanthids in turbid-zone reefs over the last 26 years (1994–2020) in the Tropical SW Atlantic Brazil. Between 1994 and 2018 no species suffered post-bleaching mass mortality. However, the recent and intense heatwaves of 2019 and 2020 caused higher mortality rates in several key foundation corals (e.g., Millepora alcicornis, Millepora braziliensis, and Mussismilia harttii) showing that the SW Atlantic reefs are not long-term protected and universal refuges. Moreover, other direct and indirect human pressures threaten these tropical reefs. Local and regional (e.g., pollution and fisheries) and large-scale pressures (e.g., global warming and marine heatwaves) act simultaneously on the health of these reefs, which intensifies negative species-specific impacts. We outline the occurrence of pressures that have been important factors responsible for the reduction in species richness and reef fish biomass, changing geo-ecological functions, altered reef composition and dominant morpho-functional groups, as well as phase shifts. Along with large-scale climatic changes, such as heatwaves, fisheries, urbanization, mining disasters, oil spills, increased sedimentation, increased warming, marine debris, contamination by domestic, agricultural, and industrial effluents, and introduction of invasive species are likely the most severe pressures on Brazilian reefs. We discuss that the “Brazilian reef refuge hypothesis” could be partially applied for some stress-tolerant massive corals during acute disturbances (short-term refuge); yet should not be assumed as a reef ecosystem-wide feature under ongoing environmental change. Therefore, we argue that it is essential to alleviate the main local and regional human impacts and to adopt resilient-based management strategies at local and global scales to protect the low-functional redundancy and higher endemism of these unique marginal coral reefs.

Considering climate change, there is no consensus on the impact of global warming on forest growth. Therefore, it is crucial to investigate the effects of climate change on tree radial growth. However, in arid eastern central Asia, the large-spatial scale radial growth-climate relationship remains poorly understood. In this study, we collected radial growth data from 13 Siberian larch (Larix sibirica) plots along an altitudinal gradient (1100–2200 m a.s.l.) in the Altai Mountains, China. Principal component analysis (PCA), bootstrapped correlation, and linear regression were conducted to detect and quantify the effects of climatic factors on radial growth and to reveal the spatial variation in the radial growth-climate relationship. Results showed that chronologies were clustered into low- and high-altitude groups. In the low-altitude group, the self-calibrating Palmer Drought Severity Index (scPDSI) in current April showed a strong positive impact on radial growth, while the previous September mean temperature and diurnal temperature range in previous July both significantly negatively affected radial growth. These three climate variables explained 63% of radial growth variance. Among them, the scPDSI, with a relative importance of 63%, was the primary limiting factor. In the high-altitude group, the current January maximum temperature and previous July precipitation were significantly negatively correlated with radial growth, while the June minimum temperature was significantly positively correlated with radial growth. These three climatic factors together contributed to 38% variance in radial growth. Furthermore, the plot-specific relationship between climate variables and radial growth varied significantly with different altitudes. As the climate becomes wetting and warming in the Altai Mountains, our result suggests that the radial growth might benefit in an altitude between 1800 and 1900 m a.s.l., where temperature and precipitation were both positively correlated with radial growth. These findings will provide a basis for sustainable forest management under global climate change.

In recent decades, anthropogenic activities have increased nitrogen (N) deposition in terrestrial ecosystems. This higher availability of N is expected to impact plant growth. However, the effects of N deposition on tree growth remain inconclusive due to the wide variability of experimental methods used. This study aimed to test the effect of short-term N addition on the intra-annual wood formation of Chinese red pine (Pinus massoniana Lamb.) in a warm-temperate forest of Central China. From 2013, solution containing 25 kg N ha-1 year-1 was applied monthly to the understory of experimental plots from April to December to double the current natural N deposition. Each week from March to December in 2014 and 2015, cambial activity and the timings and dynamics of xylem formation were monitored by collecting microcores from stems. Xylem formation lasted from March to November, producing an average of 19 and 33 cells for all studied trees in 2014 and 2015, respectively. No difference in xylem cell production was observed between control and N-treated trees. Moreover, N-treated trees had similar timings, rates and durations of xylem formation as control trees. These findings indicated that short-term N addition was unable to affect timings and dynamics of xylem formation in Chinese red pine of warm-temperate forest.

The reduction of competition through thinning increases radial growth in the stem and roots of many conifer species. However, not much is known about the effect of thinning on the dynamics of wood formation and intra-annual development of the growth ring, especially in the roots, which are an essential part of the tree for stability and resource acquisition. The aim of this study was to evaluate the effect of an experimental thinning on the dynamics and phenology of xylogenesis in the stem and roots of black spruce and balsam fir. Experimental and control trees were selected in two mature even-aged stands, one black spruce (Picea mariana (Mill.) BSP) and one balsam fir (Abies balsamea (L.) Mill.). Wood microcores were collected weekly in the stem and roots from May to October for a period of 4 years. The onset and ending of each cell differentiation phase were computed, as well as growth rate and total cell production. Results show that thinning increased the cell production rate of stem and roots of black spruce and balsam fir. This higher daily growth rate caused an increase in the total number of cells produced by the cambium. The intensity of the treatment was sufficient to significantly increase light availability for residual trees, but insufficient to modify soil temperature and water content to a point at which a significant change in the timing or duration of xylogenesis would be induced. Thus, thinning increased cell production rate and total number of cells produced in both stem and roots, but did not result in a change in the phenology of wood formation that could lead to increased risks of frost damage in the spring or autumn.

Divergent reproductive strategies of tree species generate differences in the dynamics of seed production and dispersion. The spatial and temporal variability in seed rain abundance and viability was monitored during the period 2000-2007 in four boreal stands in Quebec, Canada. The aim was to compare the inter- and intra-annual patterns of seed dispersal between species with diverging adaptive characteristics and reproductive strategies by testing the hypothesis that sympatric species can exhibit different patterns of seed dispersal according to specific ecological adaptations. The coefficient of variation (CV), representing the inter-annual variability in seed rain, was close to or higher than 1 in balsam fir (Abies balsamea [L.] P. Mill.) and white birch (Betula papyrifera Marsh.) and confirmed the mast seeding habit of the two species. In contrast, CV in black spruce (Picea mariana [Mill.] BSP) ranged between 0.24 and 0.54, indicating a more homogeneous inter-annual amount of seed dispersal because of its semiserotinous cones that preserve seeds for an indefinite period of time. The species showed divergent intra-annual patterns of seed dispersal. Most seed dispersal of the companion species was observed in September-November, while black spruce concentrated seed rain in spring, when the proportion of germinated seeds was higher. Boreal stands experience annual seed rains constituted by a gradual dispersal of seeds of different ages and originating from cones belonging to multiple cohorts. However, asynchronous seed rains in terms of quantity and quality can occur if companion species are associated to the dominant black spruce.

European beech (Fagus sylvatica L.) is highly sensitive to climatic fluctuations, and its distribution is expected to be affected by the projected climate change. In our study, we applied high-resolution stem size variation measurements to understand the effect of provenance and season on the variability in phenotypic plasticity between and within marginal beech populations. Four marginal beech populations were selected among those growing in common garden experiment in Oleszyce, Southeastern Poland. Stem circumference variation were recorded by automatic band dendrometers during 2016 – 2018. Our results highlighted the key importance of climatic conditions, namely temperature and precipitation of August as well as temperature of June and precipitation of April for stem size variation, but the effect of provenance was scares. Temperature of spring and temperature with precipitation of autumn affect onset and end of stem size variation. Thus, high intra-provenance variation in stem size changes suggests that local populations will cope with climate anomalies thanks to relatively high adaptive potential.

12 pages, 3 figures, 3 tables, supporting information https://doi.org/10.1038/s41598-019-49797-4, Terrestrial (trees, shrubs) and marine (seaweeds and seagrasses) organisms act as carbon (C) sinks, but the role of benthic suspension feeders in this regard has been largely neglected so far. Gorgonians are one of the most conspicuous inhabitants of marine animal forests (mainly composed of sessile filter feeders); their seston capture rates influence benthic-pelagic coupling processes and they act as C sinks immobilizing carbon in their long-living structures. Three gorgonian species (Paramuricea clavata, Eunicella singularis and Leptogorgia sarmentosa) were studied coupling data of population size structure, biomass and spatial distribution in a NW Mediterranean area (Cap de Creus, Spain) with feeding, respiration and growth rates. In the study area, we calculated that P. clavata sequestered 0.73 ± 0.71 g C m−2 year−1, E. singularis 0.73 ± 0.89 g C m−2 year−1 and L. sarmentosa 0.03 ± 0.02 g C m−2 year−1. To our knowledge, this is the first attempt to calculate the importance as C sinks of gorgonian species that we consider as a starting point to estimate the importance of marine animal forests in C sequestration, and to ensure appropriate management and protection especially in areas and at depths where they are concentrated, C was funded by a FI AGAUR research grant (2012_FI_B00752), CZ was funded by the Erasmus Placement fellowship, SR was funded by a Marie Curie International Outgoing Fellowship (ANIMAL FOREST HEALTH, Grant Agreement Number 327845) and assistance from P-SPHERE (COFUND Marie Curie, Grant Agreement Number 665919). The authors thank the Generalitat de Catalunya (MERS) for their support (2017 SGR - 1588)

Invasive plant species are major threats to biodiversity. They can be identified and monitored by means of high spatial resolution remote sensing imagery. This study aimed to test the potential of multiple very high-resolution (VHR) optical multispectral and stereo imageries (VHRSI) at spatial resolutions of 1.5 and 5 m to quantify the presence of the invasive lantana (Lantana camara L.) and predict its distribution at large spatial scale using medium-resolution fractional cover analysis. We created initial training data for fractional cover analysis by classifying smaller extent VHR data (SPOT-6 and RapidEye) along with three dimensional (3D) VHRSI derived digital surface model (DSM) datasets. We modelled the statistical relationship between fractional cover and spectral reflectance for a VHR subset of the study area located in the Himalayan region of India, and finally predicted the fractional cover of lantana based on the spectral reflectance of Landsat-8 imagery of a larger spatial extent. We classified SPOT-6 and RapidEye data and used the outputs as training data to create continuous field layers of Landsat-8 imagery. The area outside the overlapping region was predicted by fractional cover analysis due to the larger extent of Landsat-8 imagery compared with VHR datasets. Results showed clear discrimination of understory lantana from upperstory vegetation with 87.38% (for SPOT-6), and 85.27% (for RapidEye) overall accuracy due to the presence of additional VHRSI derived DSM information. Independent validation for lantana fractional cover estimated root-mean-square errors (RMSE) of 11.8% (for RapidEye) and 7.22% (for SPOT-6), and R2 values of 0.85 and 0.92 for RapidEye (5 m) and SPOT-6 (1.5 m), respectively. Results suggested an increase in predictive accuracy of lantana within forest areas along with increase in the spatial resolution for the same Landsat-8 imagery. The variance explained at 1.5 m spatial resolution to predict lantana was 64.37%, whereas it decreased by up to 37.96% in the case of 5 m spatial resolution data. This study revealed the high potential of combining small extent VHR and VHRSI- derived 3D optical data with larger extent, freely available satellite data for identification and mapping of invasive species in mountainous forests and remote regions.

Spruce budworm (Choristoneura fumiferana) outbreaks are important disturbance events in the boreal forests of northeastern North America, causing major growth loss and widespread tree mortality. The physiological mechanisms leading to tree mortality remain poorly understood and two important functional traits, tree-ring width and concentration of stored carbohydrate, can serve as indicators of tree vitality during defoliation. This study aims to test the hypothesis that storage starch is an indicator of tree vitality by (1) exploring the link among reductions in storage, growth and mortality, and (2) identifying starch or sugar threshold to predict the risk of mortality. We use balsam fir and black spruce, two main host species of spruce budworm. We sampled 81 trees across seven experimental sites in eastern Quebec, Canada, and assessed defoliation intensity, tree-ring growth, and tree vitality. Soluble sugar and starch concentrations in needles, twigs, and roots were measured from spring to autumn. Under conditions of increased defoliation, carbon allocation to reserves and radial growth decreased in a similar manner for both species. Starch concentration within twigs and needles in May and June was the best indicator of carbon status in defoliated trees. We observed the highest reductions in growth two to three years prior to mortality concurrently with reductions in starch in May and June. When starch concentrations were lower than 28 mg·g-1dw in needles, the probability of balsam fir mortality exceeded 50%. At this level of starch, reserves and newly produced carbon are insufficient to support tree growth and vitality.

The look on the face of the first Cuban or Florida peninsula fisherman to find a lion fish (Pterois volitans) in his nets must have been worth seeing, back in the mid-1990s. This fish had never been spotted here before, so it was a focus of attention, especially for subaqua tourists in the Western Pacific. While it is a beautiful fish its venom can be deadly, yet it is even more harmful to the ecosystem, to other fish and crustaceans, due to its voracity. Its introduction seems to come directly from marine aquarology, possibly inadvertently, and is damaging. Rapid migration has already established this invader in the tropical waters of Venezuela and further south, 25 years after the first official record in 1992. I saw it myself in the waters of the Riviera Maya in 2013–2015. The flesh could be bought at fish stalls—and its consumption was encouraged. It is one of the many cases of an alien species that has managed to be introduced in a very particular type of pollution, that of biological invasion or contamination.

It’s an early start for a couple of amateur fishermen who decide to try their luck with tuna off the coast of England. It is the beginning of July 1928, and both of them are euphoric because they know that they may be lucky: tuna have been seen in that area since late May and now seem to be abundant. Who doesn’t like to eat a good plate of grilled tuna? It is also Atlantic bluefin tuna (Thunnus thynnus), one of the finest on the market. When several boats are engaged in fishing for them in the open sea, the news spreads like wildfire and many professionals (and also recreational boats) concentrate on fishing for tuna and opening up a market that, until then, had not been presented to them. In Norway, northern France and Denmark, they are also engaged in this new type of fishing. They are not experts, but they learn quickly and use increasingly sophisticated methods to catch a fish that is undoubtedly elusive because of its agility and power.

When I first visited a coral reef, I went down from a beach next to the apartments occupied by a colleague and I near Sant Genis on Reunion Island (near Madagascar). It was the first thing in the morning in mid-December back in 1997, and I was looking for a place to take some photographs as a souvenir of the trip. We had gone there to study the feeding of various species of cnidarians in the reef area and, being a newcomer, as soon as I had the chance I rushed into the sea to see the coral structures that I had heard so much about. I found myself in a scattered and poor environment, nothing like what I had seen in documentaries and photos. This was not surprising, as the reefs on that island are considered immature, due to volcanic action, but I found myself a little disappointed to find nothing but clumps of an undefined species of staghorn coral (Acropora) here and there. The few formations I found, moreover, were defended by fierce little fish jealous of their home, and these kept harassing me by biting my fingers and legs when the occasion presented itself, so the underwater excursion ended up being a disaster. A few days later, my colleague and I located a place to carry out our experiments where the fauna was a little more abundant but, despite the polychromatic hues, I was not much encouraged by this spot where, apart from four small fish and a handful of species of coral, anemones and small gorgonians, the most exciting thing I saw was a brightly coloured nudibranch (sea slug) gliding smoothly past.

Here comes spring, and with it heat and light. It is the time for algae, utilizing the abundant nutrients that are dissolved in the seawater to proliferate, forming large populations that will become the basis of the food chain in every ocean. But not all proliferations are good for or edible by the organisms that live in the sea. Sometimes the algae proliferate abnormally, forming dense populations, from a few hundred cells per litre to tens of millions in the same volume. The worst is when, in addition, these algae have associated natural toxins and become what the specialists call harmful algal blooms, after exponential growth. They are the famous red tides, also known as discolourations (red, white, green), absolutely nothing to do with physical tides involving the rise or fall of the sea level. In some places, what was once a sporadic natural phenomenon has become a recurring nightmare for coastal residents, the creatures that inhabit the waters as well as the humans who live near the shore. Some species of algae produce toxins that enter the food chain in these organisms, killing or causing serious damage to those that consume them.

The boreal forests of Central Asia play a vital role in biodiversity protection and regional economic development. It is important to study potential changes in the growth dynamics of boreal species in a context of global change. In this study, we developed a network of 34 tree-ring chronologies for two tree species, Siberian larch (Larix sibirica Ledeb.) and Siberian pine (Pinus sibirica Du Tour). The network extended across a large latitudinal gradient (45°N to 55°N). Principal component analysis (PCA) was used to detect spatial patterns in tree radial growth during a common period 1943–2004. Results indicated an obvious clustering pattern with chronologies being divided into a northeastern (NR) and a southwestern (SR) region. Bootstrapped correlation analyses of regional climate versus aggregated chronologies showed that tree radial growth in both regions was positively associated with summer temperature (June and July). Tree radial growth in the northeastern region was however positively associated with early spring precipitation and spring Palmer Drought Severity Index (PDSI) whereas, in the southwestern region, it was characterized by negative correlations with early summer precipitation and summer PDSI. The warm pool El Nino-Southern Oscillation (WP ENSO) and North Atlantic Oscillation (NAO) regulated tree radial growth through their influence on regional precipitation and temperature. Results suggest that tree radial growth in the region may decline with future projected climate change. This study provides a more comprehensive understanding to tree growth-climate associations across Central Asia.

Quantitative assessment of planktonic organisms is a key issue in understanding biodiversity, biomass, and carbon fluxes in marine ecosystems during the ongoing Anthropocene. However, the implications of the choice of plankton sampling equipment in tropical marine ecosystems have not been fully addressed. The goal of this study was to investigate the abundance and diversity of copepods derived from two different mesh sizes, 120 and 300 μm, to determine differences that may change our perception of the actual role of the key planktonic organisms in tropical marine ecosystems, due to the fact that missing information may be a real problem in trophic estimations (e.g. benthic-pelagic coupling processes in coastal areas). Samples were collected along 650 km of coastline in the Equatorial Atlantic. The average abundance of copepods calculated using the 120 μm net was five times higher than that of the 300 μm net. However, species richness was higher when using the 300 μm net compared to that of the 120 μm. Using the 300 μm net, the number of exclusive taxa (not found in the 120 μm mesh sampling) was higher. The Venn diagram showed that 10% of the copepod taxa were recorded exclusively in 120 μm net, whereas only 30% occurred in the 300 μm net. To improve our understanding of the structure and functioning of tropical marine ecosystems, plankton nets with smaller mesh openings should always be used to estimate abundance because of the dominance of small organisms in the nutrient-poor food webs, giving a new perspective on the available energy in water column and benthic processes of suspension feeding organisms. The absence of these smaller nets will produce an inaccurate picture of the plankton communities and their contributions to other trophic levels, including the blue carbon budget estimates worldwide.

Plants exhibit morphological and anatomical adaptations to cope the environmental constraints of their habitat. How can mechanisms for adapting to contrasting environmental conditions change the patterns of tree rings formation? In this study, we explored differences in climatic conditions of permafrost and non-permafrost zones and assessed their influence on radial growth and wood traits of Larix gmelinii Rupr (Rupr) and Larix sibirica L., respectively. We quantified the contribution of xylem cell anatomy to the tree-ring width variability. Comparison of the anatomical tree-ring parameters over the period 1963–2011 was tested based on non-parametric Mann-Whitney U test. The generalized linear modeling shows the common dependence between TRW and the cell structure characteristics in contrasting environments, which can be defined as non-specific to external conditions. Thus, the relationship between the tree-ring width and the cell production in early- and latewood are assessed as linear, whereas the dependence between the radial cell size in early- and latewood and the tree-ring width becomes significantly non-linear for both habitats. Moreover, contribution of earlywood (EW) and latewood (LW) cells to the variation of TRW (in average 56.8% and 24.4% respectively) was significantly higher than the effect of cell diameters (3.3% (EW) and 17.4% (LW)) for the environments. The results show that different larch species from sites with diverging climatic conditions converge towards similar xylem cell structures and relationships between xylem production and cell traits. The work makes a link between climate and tree-ring structure, and promotes a better understanding the anatomical adaptation of larch species to local environment conditions.

Summary Environmental conditions and the structure of the dormant cambium are assumed to affect seasonal patterns of cambial activity, hence controlling allocation of non-structural carbohydrates (NSC) to growth. However, seasonal dynamics of xylogenesis, and their connections with NSC content and dormant cambium size, have been rarely assessed along an environmental gradient. We monitored xylogenesis and leaf phenology during 2012 and 2013, and NSC in 2012, for the drought-sensitive Quercus robur and the drought-tolerant Quercus pyrenaica along a water-availability gradient in the north-western Iberian Peninsula, and analysed dependencies of xylem production and phenology on the number of cells in dormant cambium. Study oak species showed comparable seasonal fluctuations in cambial activity and NSC content, despite Q. pyrenaica had a shorter growing season and a lower wood production than Q. robur. A sharp drop in spring NSC levels at all study sites evidenced that stored carbohydrates were crucial for earlywood formation. Under drier conditions, both species extended the growing period in spring and autumn, but reduced and even stopped xylogenesis in summer, showing an enhanced NSC accumulation before dormancy. A higher number of cells in dormant cambium of large dominant oaks accounted for their wider xylem increments and longer active periods. Our study demonstrates that xylogenesis is modulated by predisposing effects of dormant cambium size on xylem production and growing season length. Moreover, the high plasticity of cambial activity in deciduous oaks would confer resistance against recurrent summer drought through the improvement of the NSC status. A lay summary is available for this article.

The threshold minimum air temperature driving xylem growth of alpine Rhododendron aganniphum is lower than that commonly observed at the treeline of conifers. Understanding how alpine shrubs grow and which environmental factors drive their biomass gain could help to functionally differentiate trees and shrubs. The cambium is the main meristem responsible for wood formation in trees and shrubs. Thus, a better knowledge of cambium growth dynamics in alpine shrubs would allow explaining why shrubs displace trees above the treeline. Here, we aim to investigate the timings and dynamics of xylogenesis and to identify the thermal thresholds controlling the onset of xylem growth of Rhododendron aganniphum, a tall shrub growing above the alpine treeline on the Tibetan Plateau. Timings of xylogenesis and radial growth rates were assessed from anatomical observations of the developing xylem during three growing seasons (2011, 2012, and 2013). The threshold temperature at which xylogenesis had a 0.5 probability of being active was calculated with logistic regressions. The onset of xylogenesis was observed between mid and late June, whereas the end of xylogenesis lasted from mid to late September. Overall, the duration of xylem growth lasted 88–101 days, and 94 % of the ring was formed from June to August. The threshold for the onset of xylem growth was observed at 2.0 ± 0.6 °C for the minimum air temperature, lower than that commonly observed for treeline conifers (ca. 6 °C). This low thermal threshold allows alpine shrubs to have a growing season long enough to complete xylem production and maturation during the warmest summer months. Our results suggest that the time required to complete xylogenesis is critical to understand why shrubs displace trees above the treeline.

International audience; Sessile marine species such as Anthozoans act as ecosystem engineers due to their three-dimensional structure. Gorgonians, in particular, can form dense underwater forests that give shelter to other species increasing local biodiversity. In the last decades, several Mediterranean gorgonian populations have been affected by natural and anthropogenic impacts which drastically reduced their size. However, some species showed unexpected resilience, mainly due to the supply of new individuals. To understand the mechanisms underlying recovery processes, studies on the first life history stages (i.e. larval dispersal, settlement and recruitment) are needed. In tropical coral reefs, crustose coralline algae (CCA) are known to influence coral larvae habitat selection and settlement. This capacity however is not ubiquitous among CCA species and larvae of different coral species may have different preferences. The present work focuses on three Mediterranean gorgonians (Eunicella singularis, Paramuricea clavata and Corallium rubrum) with the objective of quantifying settlement and recruitment in presence of two common CCA species (Litophyllum stictaeforme and Litophyllum incrustans). Results showed that the presence of CCA activates earlier settlement in E. singularis and increases the density of recruits, with different trends for the three species. Our results suggest that CCA should be taken into account in the implementation of conservation strategies. Moreover, a deeper comprehension of settlement mechanisms could help improving restoration techniques based on sexual reproduction.

Understanding how severe disturbances affect forest dynamics is fundamental in ecology, conservation and management. Earthquakes of large magnitude severely impact mountain landscapes, causing strong disturbances on forests. However, it is unknown how the resilience of tree growth after strong earthquakes changes as a function of site factors as elevation. Herein, we investigated the radial-growth responses of surviving trees after the 1950-Zayu-Medog MW 8.6 earthquake which devastated the southeastern Tibetan Plateau. We reconstructed radial growth dynamics of Abies delavayi var. motuoensis after 1950 in six sites selected along an elevational transect located in the Medog valley. Post-earthquake growth responses were detected among 60% of sampled trees in the period 1950–1955, but these responses varied depending on site elevation. Trees at the alpine treeline were less disturbed compared to those located at mid and low elevations. Severe growth suppressions, including the formation of missing rings, occurred during the first three years after the earthquake, and were stronger at low elevations. Growth releases mostly occurred after 1954. Long-term growth release, lasting more than ten years, was mainly observed at low elevations, near talus fans prone to landslides and rock falls. Growth rates returned to pre-earthquake values 45 years after the earthquake occurrence. Our results evidence how tectonic influences on tree growth depend on local factors as elevation, and demonstrate that tree resilience after severe geo-hazards is contingent on site conditions.

Although cambial reactivation is considered to be strongly dependent on temperature, the importance of water availability at the onset of xylogenesis in semi-arid regions still lacks sufficient evidences. In order to explore how environmental factors influence the initiation of cambial activity and wood formation, we monitored weekly cambial phenology in Qilian juniper (Juniperus przewalskii) from a semi-arid high-elevation region of northwestern China. We collected microcores from 12 trees at two elevations during the growing seasons in 2013 and 2014, testing the hypothesis that rainfall limits cambial reactivation in spring. Cambium was reactivated from late April to mid-May, and completed cell division from late July to early August, lasting 70&ndash, 100 days. Both sites suffered from severe drought from January to April 2013, receiving &lt, 1 mm of rain in April. In contrast, rainfall from January to April 2014 was 5&ndash, 6 times higher than that in 2013. However, cambial reactivation in 2014 was delayed by 10 days. In spring, soil moisture gradually increased with warming temperatures, reaching 0.15 m3/m3 before the onset of xylogenesis, which may have ensured water availability for tree growth during the rainless period. We were unable to confirm the hypothesis that rainfall is a limiting factor of cambial reactivation. Our results highlight the importance of soil moisture in semi-arid regions, which better describe the environmental conditions that are favorable for cambial reactivation in water-limited ecosystems.