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Showing 1401 - 1600 of 1720 Journals sorted alphabetically
The Condor     Full-text available via subscription   (Followers: 28)
The Enzymes     Full-text available via subscription   (Followers: 2)
The FASEB Journal     Hybrid Journal   (Followers: 23)
The Herpetological Journal     Full-text available via subscription   (Followers: 6)
The International Journal of Advanced Manufacturing Technology     Hybrid Journal   (Followers: 6)
The Journal of Technology Transfer     Hybrid Journal   (Followers: 15)
The Knee     Hybrid Journal   (Followers: 13)
The Lancet Microbe     Open Access   (Followers: 1)
The Lichenologist     Hybrid Journal   (Followers: 4)
The Nucleus     Hybrid Journal  
The Plant Cell     Full-text available via subscription   (Followers: 23)
The Protein Journal     Hybrid Journal   (Followers: 5)
Theoretical Biology and Medical Modelling     Open Access   (Followers: 1)
Theoretical Population Biology     Hybrid Journal   (Followers: 10)
Therya     Open Access  
Tissue and Cell     Hybrid Journal  
Tissue Engineering and Regenerative Medicine     Hybrid Journal   (Followers: 10)
Tissue Engineering Part A     Hybrid Journal   (Followers: 10)
Tissue Engineering Part B: Reviews     Hybrid Journal   (Followers: 8)
Tissue Engineering Part C: Methods     Hybrid Journal   (Followers: 8)
Toxicological Research     Hybrid Journal  
Toxicology in Vitro     Hybrid Journal   (Followers: 11)
Toxicon     Hybrid Journal   (Followers: 5)
Toxicon : X     Open Access  
Traffic     Hybrid Journal   (Followers: 5)
Transactions of the Royal Society of South Australia     Hybrid Journal  
Transcription     Full-text available via subscription   (Followers: 2)
Transgenic Research     Hybrid Journal   (Followers: 1)
Translational Psychiatry     Open Access   (Followers: 14)
Transportation Planning and Technology     Hybrid Journal   (Followers: 8)
Tree Genetics & Genomes     Hybrid Journal   (Followers: 4)
Trees     Hybrid Journal   (Followers: 3)
Trends in Bioinformatics     Open Access   (Followers: 17)
Trends in Biotechnology     Hybrid Journal   (Followers: 141)
Trends in Cell Biology     Full-text available via subscription   (Followers: 37)
Trends in Microbiology     Full-text available via subscription   (Followers: 42)
Trends in Molecular Sciences     Open Access   (Followers: 2)
Trends in Parasitology     Full-text available via subscription   (Followers: 10)
Trends in Plant Science     Full-text available via subscription   (Followers: 20)
Tropical Drylands     Open Access  
Tropical Ecology     Hybrid Journal  
Tropical Freshwater Biology     Full-text available via subscription  
Tunnelling and Underground Space Technology     Hybrid Journal   (Followers: 10)
Turkish Journal of Agricultural and Natural Science / Türk Tarım ve Doğa Bilimleri Dergisi     Open Access  
Ukrainian Journal of Ecology     Open Access  
Ultrasound in Medicine & Biology     Hybrid Journal   (Followers: 10)
UNED Research Journal / Cuadernos de Investigación UNED     Open Access  
Uniciencia     Open Access  
Universal Journal of Biomedical Engineering     Open Access  
UNM Journal of Biological Education     Open Access  
Unnes Journal of Biology Education     Open Access  
Vakuum in Forschung und Praxis     Hybrid Journal   (Followers: 2)
Vascular Cell     Open Access  
Vegetation Classification and Survey     Open Access  
Victorian Naturalist, The     Full-text available via subscription   (Followers: 2)
View     Open Access   (Followers: 3)
Virchows Archiv     Hybrid Journal   (Followers: 3)
Virologica Sinica     Hybrid Journal  
Virology Journal     Open Access   (Followers: 5)
Virulence     Open Access   (Followers: 1)
Virus Evolution     Open Access   (Followers: 3)
Virus Genes     Hybrid Journal   (Followers: 1)
Virus Research     Hybrid Journal   (Followers: 1)
Visnyk of Dnipropetrovsk University. Biology, ecology     Open Access   (Followers: 1)
Visnyk of Dnipropetrovsk University. Biology, medicine     Open Access  
VITIS : Journal of Grapevine Research     Open Access   (Followers: 1)
Walailak Journal of Science and Technology     Open Access  
Water Biology and Security     Full-text available via subscription   (Followers: 5)
Web Ecology     Open Access   (Followers: 3)
Webbia : Journal of Plant Taxonomy and Geography     Hybrid Journal  
West African Journal of Applied Ecology     Open Access  
Western Undergraduate Research Journal : Health and Natural Sciences     Open Access  
Wetlands     Hybrid Journal   (Followers: 25)
Wildlife Biology     Open Access   (Followers: 16)
Wildlife Research     Hybrid Journal   (Followers: 17)
Wiley Interdisciplinary Reviews - System Biology and Medicine     Hybrid Journal   (Followers: 2)
Wiley Interdisciplinary Reviews : Developmental Biology     Hybrid Journal   (Followers: 2)
Wiley Interdisciplinary Reviews : Membrane Transport and Signaling     Hybrid Journal  
Wiley Interdisciplinary Reviews : RNA     Hybrid Journal   (Followers: 3)
World Mycotoxin Journal     Hybrid Journal   (Followers: 3)
Xenobiotica     Hybrid Journal   (Followers: 7)
Yeast     Hybrid Journal   (Followers: 8)
Zebrafish     Hybrid Journal  
Zeitschrift für Evidenz, Fortbildung und Qualität im Gesundheitswesen     Hybrid Journal   (Followers: 6)
Zitteliana     Open Access  
Zygote     Hybrid Journal  

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Similar Journals
Journal Cover
Trees
Journal Prestige (SJR): 0.726
Citation Impact (citeScore): 2
Number of Followers: 3  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0931-1890 - ISSN (Online) 1432-2285
Published by Springer-Verlag Homepage  [2469 journals]
  • Estimation of ploidy levels by flow cytometry and identification of
           Torreya grandis cultivars and breeding strains by SSR markers

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      Abstract: Key message This study is the first to report a core set of polymorphic SSR markers in Torreya grandis developed to identify T. grandis cultivars and breeding strains and estimate ploidy levels. Torreya grandis Fort. ex Lindl has a high economic value because it produces edible, nutrient seeds with high oil content as food for thousands of years in China. T. grandis has rich variation in morphological traits and ploidy levels as well as commonly occurring natural hybridization. In this regard, an efficient molecular method should be developed to identify T. grandis cultivars and strains and determine ploidy levels for breeding program. In this study, 25 T. grandis materials with different ploidy levels including 17 cultivars and 8 strains were collected and analyzed with a core set of 10 polymorphic simple sequence repeat (SSR) markers developed from the transcriptome data. The ploidy level of the materials was estimated through SSR marker genotyping and flow cytometry (FCM). The polymorphism information content (PIC) values for 10 SSR loci indicated that six loci were highly polymorphic, three loci were average polymorphic, and one loci was low polymorphic. The SSR genotyping profiles and the UPGMA clustering demonstrated that the 10 core SSR markers can be used as effective DNA fingerprints to identify most of the 25 T. grandis materials including all polyploids. The ploidy level estimated from SSR marker genotyping corresponded with that estimated by FCM among 17 diploid and 5 triploid materials but not among 1 tetraploid. Tg_U33 was a highly heterozygous locus that can be used to rapidly and efficiently identify ploidy levels in T. grandis materials from a large number of samples.
      PubDate: 2022-07-02
       
  • Responses of radial growth of Picea crassifolia to climate change over
           three periods at different elevations in the Qilian Mountains, northwest
           China

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      Abstract: Key message Qinghai spruce at different elevations showed inconsistent growth trends and responses to climate change. Under global warming, mountains in arid and semi-arid regions have become the main ecologically vulnerable areas affected by climate change. Northwest China has experienced intermittent climate change in recent decades that can be divided into three periods: steady change (T1), a rapid temperature increase (T2) and a warming hiatus (T3). How this unsteady change in climate has affected the growth and response of trees at different elevations in the region remains unclear. Therefore, we established three standard chronologies of Qinghai spruce (Picea crassifolia) at high, middle and low elevations in the central Qilian Mountains to investigate its responses during different periods. We drew three primary conclusions. First, trees at high elevations are primarily impacted by higher temperatures, while trees at middle and low elevations are mainly impacted by water stress due to drought. Second, trees at the three elevations showed unstable responses to all temperature factors, while those at the middle and low elevations showed relatively stable responses to total precipitation in the late growing season of the previous year. Third, different interannual growth variations were observed at the three elevations, indicating a nonsignificant change at high elevations and significant declines at middle and low elevations. At the same time, growth patterns were different for the three climatic periods. Therefore, the dominant conifers at different elevations of the Qilian Mountains showed inconsistent responses during different periods. It is necessary to take effective measures to manage forest ecosystems according to spatial and temporal adaptation strategies for climate change.
      PubDate: 2022-07-01
       
  • Effect of climate on cork-ring width and density of Quercus suber L. in
           Southern Portugal

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      Abstract: Abstract Cork rings have been extensively used in dendroecological studies of the Mediterranean evergreen cork oak (Quercus suber L.). Through measurements of cork-ring width only, strong relationships have been found between cork-ring widths and climate parameters. To our knowledge, cork-ring density, which is an important cork quality attribute, has never been used in any dendroecological study to explore physiological responses of the cork oak to climate change. In this study, we measured cork-ring width and density over 50 years (1962–2013), corresponding to five consecutive cork harvests, and analyzed their inter-annual fluctuations in eight trees from two different sites, a wetter peneplain area (Benavente) and a drier mountainous area (Grândola). Our results revealed a statistically significant correlation between cork-ring width and density (p < 0.05) at both sites; however, it was negative (r =− 0.261) and relatively weaker at Benavente, and positive at Grândola (r = 0.410). Moreover, a direct relationship between cork density and spring–summer temperature was found only at Grândola. Here, cork growth sensitivity to inter-annual variability of precipitation and temperature in summer-autumn of the current growth year (p < 0.01) was the highest and, respectively, positive and negative. We conclude that in drier Mediterranean environments, summer drought stress might negatively affect both cork growth and density, by changing tree physiological processes involved in cork formation, resulting in narrower and denser cork rings. Considering scenarios of future climate change effects in Southern Europe, in particular the longer drought periods and rising temperatures, it seems that both cork yield and cork density will be affected, with implications on cork quality.
      PubDate: 2022-06-29
       
  • Combined effects of tree size and tapping techniques on resin production
           of Boswellia dalzielii Hutch., an African frankincense tree

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      Abstract: Key message Slant incisure tapping yielded the highest resin production. Resin production was proportional to tree size, tapping intensity, and frequency. Resin production was higher during hot dry season than cold dry season. Boswellia dalzielii Hutch. is an African frankincense tree species with high medicinal and economic values mostly derived from its resin. In Burkina Faso, it has potentials to be the source of significant income for local communities, but it is currently neglected and underutilized. This study aims to assess the species resin production in relationship to tree size, tapping technique, season, intensity, and frequency of harvesting in natural stands of Sudano-Sahelian zone of Burkina Faso. Two independent experiments were conducted on resin yield: (i) experiment 1 combined the tapping technique (six techniques) and tree stem-diameter (10–20 vs. 20–30 cm) using 120 trees; (ii) experiment 2 used the slant incisure tapping technique (best from the first experiment) and combined five tapping intensities (number of grooves: 2, 4, 6, 8 and 10), period of tapping (cold vs. hot dry season), and tree stem-diameter (10–20, 20–30, and > 30 cm), using 90 trees. For each experiment, resin production was collected every 2 weeks for 12 weeks. Analysis of variance and linear mixed model on longitudinal data were used for data analyses. All trees had exudated resin and the average resin yield per tree was 36.28 ± 8.62 g (experiment 1) and 40.43 ± 3.82 g (experiment 2). Tapping techniques and intensity, and tree stem-diameter had significant (P < 0.001) effect on resin yield. Slant incisure tapping yielded the highest resin production, followed by tapping in E-shape cut, V-shape cut and circular tape (intermediate yield production), whereas thin deep vertical incisure and node tape gave the lowest resin production. Larger trees exuded higher quantity of resin. Higher tapping intensity and frequency (wound renewal) also gave higher resin production. Trees tapped during hot dry season produced 1.23 times higher quantity of resin (44.58 ± 7.51 g) than in cold dry season. The findings of this research could help design better harvesting strategies for the sustainable management of B. dalzielii resources in West Africa.
      PubDate: 2022-06-25
       
  • Frankia diversity in sympatrically occurring red alder (Alnus rubra) and
           Sitka alder (Alnus viridis) trees in an early successional environment

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      Abstract: Key Message Frankia diversity on Mount St. Helens has recovered to regionally-observed levels, but small-scale geographic heterogeneity affects host-specificity of Frankia communities in red and Sitka alder. Alders (Alnus sp.) are key pioneer tree species in disturbed and nutrient-poor ecosystems. Due to their association with nitrogen-fixing Frankia bacteria they have a disproportionate impact on soil quality and successional processes. However, surprisingly little information exists on the host-specificity and colonization patterns of Frankia communities among sympatrically occurring alder hosts in nature. We analyzed variation in Frankia community composition in sympatric red alder (Alnus rubra) and Sitka alder (Alnus viridis) root nodules from the Pumice Plain of Mount St. Helens, WA (Lawetlat'la in the Cowlitz language; USA). Five 2500 m2 plots containing both red (n = 11) and Sitka alder (n = 12) trees were sampled along a 1.5-km transect. Five root nodules were collected from each tree, and Frankia genotypes were assessed by sequencing both nifH and 16S rRNA genes. In addition to root nodules, soil samples were collected from the rhizosphere of each tree for chemical analyses. We did not observe within-tree variation as only one Frankia genotype was detected per host tree, and the overall observed Frankia diversity was low and comparable to other studies of Alnus–Frankia symbioses. The most abundant nifH genotype was observed in both alder host species, in all plots, and occurred in 70.8% of all samples (69.6% of all trees). However, community composition was significantly different among plots (PERMANOVA, p = 0.002). Comparisons of communities among plots revealed modest correlations between geographic distance and community similarity (Mantel test, p = 0.001). Our findings suggest that even small-scale spatial variation and microenvironment conditions can affect an important plant–microbe symbiosis, which may have consequences for host local adaptation.
      PubDate: 2022-06-23
       
  • Laurel wilt susceptibility of three avocado (Persea americana Mill.)
           ecotypes in relation to xylem anatomy, sap flow and leaf gas exchange

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      Abstract: Key message Relative susceptibility to laurel wilt among clonal, non-grafted avocado trees of different ecotypes is relate to the xylem vessel diameter, with larger vessels potentially allowing more rapid movement of fungal conidia in the transpiration stream, creating a potential for faster colonization of the vascular system by the pathogen. Laurel wilt, caused by the fungus Harringtonia lauricola, is a devastating vascular disease prevalent in avocado (Persea americana Mill.) orchards in Florida, where it has caused significant tree losses. Differential susceptibility to laurel wilt has been observed among grafted trees of three avocado ecotypes, Guatemalan (G), and West Indian (WI), and Mexican (M) with grafted WI cultivars reportedly the most susceptible. It has been suggested that differential susceptibility among ecotypes is related to the rate of xylem sap flow as affected xylem vessel size and density. This study compared laurel wilt susceptibility among representative clonally propagated, non-grafted cultivars of three ecotypes (G, WI, and M × G) in relation to xylem vessel anatomy, xylem sap flow rate, net CO2 assimilation (A), stomatal conductance (gs), transpiration (E), intrinsic water use efficiency (WUE), the leaf chlorophyll index (LCI), the ratio of variable to maximum chlorophyll fluorescence (Fv/Fm) and hydraulic conductance (Kh). Laurel wilt negatively affected all physiological variables measured and caused a profuse development of tyloses that blocked the xylem vessels and inhibited xylem sap flow in trees of each ecotype. Differences in disease susceptibility were observed among ecotypes, which were related to xylem vessel size, xylem sap flow, and the development of tyloses in xylem vessels. Trees of the ecotype with the greatest inherent functional xylem vessel diameter and sap flow rates were more susceptibility to the disease after inoculation with H. lauricola. Trees of the M × G ecotype formed the most tyloses which blocked the xylem vessels resulting in a greater decrease in sap flow compared to trees of the other ecotypes.
      PubDate: 2022-06-22
       
  • Recovery of trembling aspen, tamarack, and white spruce seedlings from
           NaCl stress following winter dormancy: implications for increased foliar
           potassium, necrosis, and sodium management as stress resistance mechanisms
           

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      Abstract: Key message Different tree species exposed to NaCl stress exhibited similar responses including elevated foliar K, increased foliar necrosis, as well as the exclusion or accumulation of foliar Na. Revegetation of boreal forest lands disturbed by surface mining for bitumen can be challenging due to fluctuating levels of soil NaCl and harsh winter temperatures. These stressors may hinder the growth and survival of planted tree seedlings. Two experiments were carried out to examine the processes of recovery from NaCl stress and overwintering in trembling aspen, tamarack, and white spruce seedlings. In the recovery experiment, seedlings were treated with 0, 50, or 100 mM NaCl for 60 days and then allowed to recover for 60 days. Most of the examined physiological variables (total dry weight, chlorophyll concentration, photosynthesis, and transpiration) in all examined species returned to control levels after 30 days of recovery from the NaCl treatment. In the overwintering experiment, seedlings were subjected to 0 or 50 mM NaCl treatment throughout the first growing season, overwintered, and treated with 0, 50, or 100 mM NaCl for 8 weeks during the second growing season. All tested species exhibited foliar chlorosis and necrosis from NaCl treatment in the first year. Several similarities were observed between species in both experiments, including increased foliar K and necrosis in trembling aspen and tamarack. Trembling aspen exhibited remarkably low foliar Na, whereas tamarack and white spruce had high concentrations of foliar Na despite the recovery of physiological variables to control levels. Elevated foliar K, necrosis, and Na management may constitute important salt resistance mechanisms for the tree species tested.
      PubDate: 2022-06-17
       
  • Differentiating refilling and transpiration from night-time sap flux based
           on time series modelling

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      Abstract: Key message Although night-time transpiration occurs most of the time, stem refilling contributed more to the amount of night-time sap flux, which indicates that there was no water loss in Schima superba at night-time. It has been historically shown to be difficult to identify the night-time transpiration (En) and stem refilling (Rn) components from night-time sap flux (NFt). We applied an autoregressive moving-average (ARMA) model with exogenous variables (ARMAX) fitting En to distinguish NFt of Schima superba for avoiding autocorrelation. In total, 23 optimum models were chosen at the node moments of the night in the dry and wet seasons. Models performed seasonal variations in involving environmental factors and build time. Vapor pressure deficit (VPDt) alone or with wind speed (WSt) drove positively NFt in most of the time in both seasons. SMt dominated NFt only at the beginning of the night-time in the dry season. En occurred 1 h later and was lower in the wet than in the dry season (ca. 1.09 kg h−1 vs 1.82 kg h−1), and Rn is the opposite (ca. 2.36 kg h−1 vs 1.9 kg h−1). This may cause by greater water storage deficit in the trunk due to stronger day-time transpiration. We found that NFt was minor compared to day-time sap flux (DFt), and the mean ratio of night-time sap flow (Qn) to daily sap flow (Qw) was only 0.02. Our results showed that there were no seasonal differences on the contribution of NFt to the 24-h Ft, and no water loss at the daily scale in Schima superba in both seasons (Rn > En). This study first quantifies En and Rn, and reveals seasonal variations in tree night-time water use and provides a basis for better understanding of En function.
      PubDate: 2022-06-17
       
  • Age-related tree-ring sensitivity at the dry forest-steppe boundary in
           northwestern Patagonia

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      Abstract: Key message The association between growth and climate in the forests of Austrocedrus chilensis placed at the forest-steppe ecotone was found to be age dependent, with ring widths from the oldest trees providing a better expression of climate variability. Over the course of their lives, trees may undergo changes in sensitivity to climate during their ontogenetic development, i.e., from seedling to maturity. Identifying these age-dependent responses is relevant to minimize under or over estimations of the climatic signal in dendroclimatic reconstructions. It also provides important clues in predicting the reactions of different age-class trees to ongoing climate changes. In this context, the main goal of this study was to determine the sensitivity of radial growth of Austrocedrus chilensis (Ciprés de la Cordillera) to climate variability as a function of tree age. Wood cores from 90 trees growing in the forest-steppe ecotone of northwestern Patagonia in Argentina, were sampled. By analyzing their growth rings, trees were classified in two age classes: young (< 93 years) and mature (≥ 93 years). Pearson’s and moving correlations revealed that spring-early-summer total precipitation positively correlated with growth regardless of age, particularly during the previous growing season. Mean temperature and standardized precipitation-evapotranspiration index (SPEI-1 month), however, showed a stronger association with the growth of mature trees than with young trees, especially in relation to the previous growing season. The moving correlation analysis showed, moreover, that the associations between climatic variables and radial growth of A. chilensis varied between age classes during the last century. The obtained results could help to improve our understanding of the ecology of A. chilensis and provide a better interpretation of how Patagonian forests could be influenced by climate change processes.
      PubDate: 2022-06-08
       
  • Effects of climate on the tree ring density and weight of Betula ermanii
           in a cool temperate forest in central Japan

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      Abstract: Key Message The tree ring weight of Betula ermanii was primarily controlled by the ring width, but not by its ring density. The climate responses of them were clarified by dendrochronological analysis. Global warming scenarios have made the understanding of carbon sequestration changes in the stems of forest trees important. However, there is a lack of understanding about climate change’s effects on the wood density of hardwood, which is a crucial indicator of wood biomass. Therefore, we investigated the effects of climatic factors on the ring density and ring weight of B. ermanii, a dominant tree species in cool temperate regions and subalpine regions of Japan. We calculated the annual ring weight growth by multiplying the ring width and density. We developed the residual chronologies of the ring density and weight and performed a correlation analysis between the chronologies and the climate data. We deduced that the ring density was independent of the ring width for individual cores. The ring weight chronology showed a positive correlation with the ring width but not with ring density. The ring density decreased due to higher temperature, long sunshine duration, and less precipitation from mid-July to early October in the previous year. Conversely, those from mid-June to mid-August increased the ring density in the current year. The previous year’s high nighttime temperature in autumn and dry conditions during the current year’s summer decreased the ring weight, similar to the climate responses of ring width. Therefore, we concluded that ring weight was not controlled by ring density, but majorly regulated by ring width. Conclusively, this study’s results can evaluate the impact of climate change on the carbon sequestration potential of the stem of B. ermanii.
      PubDate: 2022-06-04
       
  • Dry and hot years drive growth decline of Pinus halepensis at its southern
           range limit in the Moroccan High Atlas Mountains

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      Abstract: Key message Pinus halepensis trees at the southern limit of the species distribution show less growth, low relative resilience, and more missing rings in response to increased temperatures and droughts. Climate change is increasing the frequency and intensity of extreme droughts in the northern hemisphere, leading to forest decline and tree mortality. Species are more vulnerable to climate fluctuations at the rear-edge limits of their distribution ranges. Pinus halepensis Mill. is a Mediterranean conifer with its southern distribution limit in the High Atlas Mountains of Morocco. The purpose of this study was to analyse the climate response of P. halepensis tree rings from the High Atlas Mountains of Morocco, and to determine its resilience to extreme drought events. Climate data for the study site revealed that temperature has significantly increased in recent decades, but precipitation remained unchanged, resulting in increased aridity. The ring-width time series revealed several missing rings since 1999, possibly linked to the increased aridity. Tree-ring width responded negatively to spring and summer maximum temperature and positively to previous winter and spring precipitation. Moving correlation analysis revealed an increased negative relation with maximum temperature in April, June, and July, supporting the adverse effect of global warming on P. halepensis growth. Resilience analysis revealed that trees were able to recover from extreme droughts, but its detrimental effect remained in the following years. Pinus halepensis trees at the southern limit of their distribution are already suppressing growth in extreme drought years. If the frequency of extreme droughts increases, as predicted by climate change models, the recovery capacity of these trees will be compromised, resulting in habitat loss and in the potential contraction of the species southern range.
      PubDate: 2022-06-03
       
  • Receptiveness of soil bacterial diversity in relation to soil nutrient
           transformation and canopy growth in Chinese fir monoculture influenced by
           varying stand density

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      Abstract: Key message Varying stand density was the principal factor altering bacterial diversity compared to soil properties. Soil bacteria with a higher alpha diversity were present in low stand density. Absract Different land-use patterns and silvicultural practices contribute to the shifting composition and assemblage of soil bacterial communities. Positive plant and soil responses to nutrient acquisition, promotion of sustainable growth, resistance to biotic and abiotic stress, and disease suppression depend on favorable interactions between plant roots and microbes. This study investigated the community assemblage of soil bacteria and its interaction with soil quality indicators and canopy growth parameters (e.g., mean tilt angle of the leaf (MTA), leaf area index (LAI), and canopy openness index (DIFN)) in low, intermediate and high density stands of Chinese fir plantation at two soil depths (0–20 and 20–40 cm). The results showed that the soils of the low-density stand had higher α-bacterial diversity than the soils of medium and high-density forests. Among all variables, Acidobacteria was the most dominant phylum with 24.72%, followed by Actinobacteria, Proteobacteria and Chloroflexi with 20.41%, 15.89%, 11.67%, respectively. Among different canopy parameters, low-density associated bacterial diversity was positively correlated with the canopy openness index. Among soil properties, potassium, nitrogen, and phosphorus were considerably influential factors to bacterial communities. Redundancy analysis (RDA) results showed that soil physiochemical properties accounted for 31.86% of the total migration of the soil bacterial communities. Although soil attributes were the significant contributing factors affecting bacterial communities, varying stand density was the main factor altering bacterial diversity. By revealing changes in soil bacterial relative abundance and richness patterns at different levels of stand density, this study would provide comprehensive proof of the complexity of belowground ecology. It will also serve as a foundation for developing sustainable management strategies in silty oxisol soil types and plantation crops.
      PubDate: 2022-06-01
       
  • Bases for genetic conservation of Freziera atlantica, an endangered wood
           species and endemic to the Atlantic Forest hotspot

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      Abstract: Key Message Freziera atlantica is an endangered species. It was found that intrapopulation genetic diversity is high, possibly maintained by the seed bank, but human disturbances threaten the population. In the Anthropocene, one of the major concerns worldwide is related to landscape disturbances, causing changes in the planet’s climate and declining genetic diversity of plant populations. Establishing concrete plans for genetic conservation of species is a great challenge, with knowledge of their genetic variations as a key element. In this study, we evaluated the diversity and genetic structure of an isolated population of the endangered species F. atlantica, focused on the purpose of contributing to the conservation of tree plants and the future mediation identification of tree matrixes for seed collection. Total genomic DNA from 44 adult individuals was extracted and purified. Thus, diversity, similarity and population genetic structure were measured from ISSR genotyping. Polymorphisms between the analyzed individuals were identified in the electrophoretic analysis by the presence or absence of bands. The results indicate low polymorphism among the F. atlantica individuals (46.6%) studied, possibly as a response to population isolation and aggregate distribution at the site. However, genetic diversity can be considered high and is possibly maintained by a self-incompatibility mechanism as a response to dioecy. Our results are a first approach for the structuring and genetic diversity in the neotropical Freziera genus and the first steps to acquire knowledge of biological aspects and proposition of in situ and ex situ conservation strategies for F. atlantica.
      PubDate: 2022-06-01
       
  • Trimming influences tree light interception and space exploration:
           contrasted responses of two cultivars of Fraxinus pennsylvanica at various
           scales of their architecture

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      Abstract: Key message Complementarities and/or synergies among different scales of tree architecture enable to achieve different functions simultaneously and/or optimize one function. After trimming, tree reaction occurred in all the scales. Trees are modular organisms within which each scale has attributes enabling them to optimize different functions. Among these functions, space exploration and light interception are strong determinants of tree productivity and survival. By modifying the crown shape, including foliage dispersion in the 3D space and carbon allocation, tree trimming (i.e. the removal of the higher part of the crown) may largely influence how trees fulfill the space exploration and light interception functions. In this study, we used field measurements of tree annual shoots combined with tree reconstruction from Terrestrial Laser Scanning data to analyze how different scales of the tree architecture complement each other to fulfill different functions simultaneously or combine to fulfill one single function more efficiently. We used morphological and functional variables measured at the annual shoot, axis, and tree scales to compare the architectural and functional strategies of two Fraxinus pennsylvanica cultivars and observe how trimming modifies these strategies. Results show that the two cultivars exhibit different strategies. One cultivar tended to optimize the space exploration function at both the annual shoot and axis scales and to optimize the light interception by displaying a large leaf area at the tree scale. The other cultivar tended to optimize light interception efficiency at both axis and tree levels. In both cultivars, trimming improved light interception efficiency and increased investments into space exploration. Nevertheless, after trimming, the two cultivars maintained their main architectural and functional strategy.
      PubDate: 2022-06-01
       
  • Legacy effect of extreme wetness events on subsequent tree growth
           

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      Abstract: Key message Extreme wetness changed the pattern of tree water uptake and improved tree water status at the beginning of the growing season in the subsequent year. Improved understanding of tree and ecosystem responses to precipitation changes is paramount for their conservation and management. However, not much is known about the influence of extremely high rainfall periods on forest ecosystems. In this study, tree stem growth, water use uptake, leaf water potential, and leaf water use efficiency of Pinus tabulaeformis plantations were assessed to investigate the legacy effects of extreme wetness events on subsequent tree growth in a semi-arid region of North China. The soil water content in 20–40 cm and 40–80 cm soil layers was higher than that in 0–10 cm and 10–20 cm layers after an extreme wetness event in 2018, and the high soil water content lasted until July 2019. This consequently increased the ratio of tree water uptake from middle and deep soil layers, and improved tree water status at the beginning of the growing season, which can be explained by strong stem growth increase observed in 2019. These findings reveal regional forest dynamics under increased precipitation pattern variability, and play a vital role in providing adaptive forest management strategies in semi-arid regions of North China.
      PubDate: 2022-06-01
       
  • Temporal expression of defense-related genes in Ganoderma-infected oil
           palm roots

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      Abstract: Key message Salicylic acid-mediated early defense response in asymptomatic oil palm roots infected by Ganoderma boninense . Jasmonic acid-mediated defense response in oil palm with root lesions caused by Ganoderma boninense . The oil palm defense responses could not eradicate basal stem rot but may delay deterioration of infected oil palms. Basal stem rot is an oil palm disease which causes substantial loss to the oil palm industry in Southeast Asia. Temporal gene expression analysis of oil palms infected with Ganoderma boninense is important to identify the defense pathways at biotrophic and necrotrophic phases of fungal infection. The aim of this study was to analyze the gene expression of oil palm genes related to respiratory burst oxidation, phytohormone biosynthesis, salicylic acid- and jasmonic acid-mediated defense pathways in oil palm roots infected by G. boninense at different time points. The findings of this study confirmed that salicylic acid mediated the early defense response from infected oil palm during the biotrophic phase of fungal infection, while the JA-mediated defense response was triggered when the root lesions occurred in the infected oil palm root tissues during the necrotrophic phase of Ganoderma infection. The oil palm defense responses may play a role in delaying the progression of basal stem rot but is insufficiently effective to eradicate Ganoderma infection. Temporal gene expression may help in finding methods to ameliorate the impact of basal stem rot by prolonging the productive lifespan of diseased trees and to reduce the economic loss due to this disease.
      PubDate: 2022-06-01
       
  • Industrial scale-up of tissue-cultured Dracaena cambodiana Pierre ex
           Gagnep

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      Abstract: Key message An in vitro-to-ex vitro shoot tip-derived protocol was developed to mass propagate (40,000 plants/year) Dracaena cambodiana . Dracaena cambodiana Pierre ex Gagnep (Agavaceae) has considerable ornamental and medicinal value, but due to over-exploitation of its natural stands, it has become endangered. In this study, we developed an in vitro-to-ex vitro protocol that allows for the mass propagation (micropropagation) of this plant. A regeneration protocol was developed for this plant from the culture of shoot tips. Callus and then adventitious shoots were induced on MS medium supplemented with 2.0 mg/L BA and 0.5 mg/L NAA while 2.0 mg/L TDZ and 1.0 mg/L BA in MS medium induced resembling somatic embryo-like structures, each which was able to develop a radicle, a hypocotyl and shoot. BA induced hyperhydricity when used at 4.0 mg/L. When cultured on ½MS medium with 0.5 mg/L of either NAA or IBA, 100% of shoots formed roots within one month. Almost 100% of plantlets transferred to a substrate of coconut husk and peat (1:1, v/v) survived. This study also reports the first large-scale production of D. cambodiana plantlets in plastic bags (40,000 plants/year), with the potential for more than 1 million plants/year, allowing for market demand to be met and plants to be produced in sufficient volumes for eco-restoration projects.
      PubDate: 2022-06-01
       
  • Effects of climate and protection status on growth and fruit yield of
           Strychnos spinosa Lam., a tropical wild fruit tree in West Africa

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      Abstract: Key Message Strychnos spinosa growth was less responsive than its fruit production, to tree size, protection status and climate; its fruit production increased with tree size, and more so on protected sites. Abiotic and biotic mechanisms (e.g. climate, human perturbations) are presumed to shape tree growth and reproductive performances. Using the wild fruit tree Strychnos spinosa Lam., as a case study in Benin, we tested whether (and how) tree growth and fruit production were influenced by protection status (non-protected vs. protected sites), climatic zones (Sudanian vs. Sudano-Guinean zones) and size classes (tree diameter < 15 cm; 15–20 cm and > 20 cm). We also tested which climatic variables were important in predicting tree growth/fruit production. Tree growth was only influenced by size class, with higher growth rate in smaller than bigger size classes. Unlike tree growth, fruit production varied significantly with climate and protection status (higher fruit production in Sudano-Guinean than in sudanian zone, and on protected sites than non-protected sites). Fruit production also increased with tree size, and more so on protected sites than non-protected sites. The effect of protection status on fruit production also varied with climatic zones, with protected trees having more fruits than non-protected trees in Sudano-Guinean zone, while both protected and non-protected trees showed similar fruit production in the Sudanian zone. There was a trade-off mechanism between fruit production and growth, which was more pronounced on protected sites. Our study showed that both climate and protection status were considerably important for fruit production, in significant positive (resp. negative) effects of temperature and relative humidity, via mediation by tree size in protected (resp. non-protected) sites. These underlying drivers should be taken into account when predicting scenario for fruit yield under future climate.
      PubDate: 2022-06-01
       
  • Strategies of urban trees for mitigating salt stress: a case study of
           eight plant species

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      Abstract: Key message Some species synthesize larger amounts of polyprenols, which probably increase the plant’s ability to mitigate salt stress. Salt stress does not cause macronutrient deficiency in the leaves of urban trees. Ionic imbalance in the leaves caused by soil salinity worsens the health status of sensitive species. Street trees are exposed to relatively high stress levels, and the average lifespan of street trees is shortened compared to those of trees living under controlled natural conditions. Soil salinity adversely affects trees at all stages of growth and development. This study attempts to determine how the urban environment, with particular emphasis on salt stress, affects tree species with different levels of salinity sensitivity. The aim of this study was to identify the strategies of eight tree species for mitigating salt stress based on the determination of the chemical composition of the macroelements in the leaves, the ionic imbalance, and the ability of the trees to synthesize and accumulate polyprenols in the leaves. The obtained results suggest that individual species implemented different strategies in response to salt stress. The low sensitivity species: Q. rubra, R. pseudoacacia, G. triacanthos and A. campestre. blocked the uptake of Cl and Na to the leaves. The medium-sensitivity species: P. x hispanica blocked the uptake of Cl and Na and G. biloba maintained very high contents of Cl and Na in its leaves without leaf damage and synthesized large amounts of polyprenols. G. triacanthos and A. campestre synthesized large amounts of polyprenols. The high-sensitivity species (T. x euchlora and A. platanoides) exhibited very high contents of Cl and Na in their leaves, which were significantly damaged and had a pronounced ionic imbalance. These effects were not compensated for by the increased synthesis of polyprenols. In conclusion, the accumulation of polyprenols in leaf tissue may be one of the strategies that increase the resistance of plants to salt stress. Plants have many other methods of mitigating salt stress.
      PubDate: 2022-06-01
       
  • Intra-annual tree-ring isotope variations: do they occur when environment
           remains constant'

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      PubDate: 2022-04-20
       
 
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