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1.
Ecotoxicol Environ Saf ; 183: 109475, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31442810

RESUMO

Community-scale impacts of glyphosate-based herbicides on wetland plant communities and the magnitude of those impacts that should be considered biologically relevant are poorly understood. We contrast three different thresholds for setting biologically meaningful critical effect sizes for complex ANOVA study designs. We use each of the of the critical effect sizes to determine optimal α levels for assessment of how different concentrations of glyphosate-based herbicides affect wetland plant communities over two years of herbicide application (alone and in combination with agricultural fertilizers) and two subsequent years without herbicide (or fertilizer) application. The application of glyphosate-based herbicides was found to result in a decrease in macrophyte species richness, an increase in macrophyte species evenness, a decrease in macrophyte cover and a reduction in community similarity. There was little evidence that nutrient additions directly or indirectly affected plant community endpoints. The glyphosate effects were evident in the first year of herbicide application in 2009, and became more pronounced in the second year of herbicide application in 2010. However, when herbicides were not applied in 2011, recovery was observed in most endpoints, with the exception being species evenness, for which partial recovery was not observed until 2012. Optimal α levels differed among the three critical effect sizes for each ANOVA term and endpoint combination, however regardless of differences in α levels, conclusions were generally consistent across all critical effect sizes.


Assuntos
Acer/efeitos dos fármacos , Betula/efeitos dos fármacos , Glicina/análogos & derivados , Herbicidas/toxicidade , Picea/efeitos dos fármacos , Áreas Alagadas , Acer/crescimento & desenvolvimento , Agricultura , Betula/crescimento & desenvolvimento , Glicina/toxicidade , Modelos Teóricos , Novo Brunswick , Picea/crescimento & desenvolvimento
2.
BMC Plant Biol ; 19(1): 240, 2019 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-31170934

RESUMO

BACKGROUND: Red maple (Acer rubrum L.) is one of the most common and widespread trees with colorful leaves. We found a mutant with red, yellow, and green leaf phenotypes in different branches, which provided ideal materials with the same genetic relationship, and little interference from the environment, for the study of complex metabolic networks that underly variations in the coloration of leaves. We applied a combination of NGS and SMRT sequencing to various red maple tissues. RESULTS: A total of 125,448 unigenes were obtained, of which 46 and 69 were thought to be related to the synthesis of anthocyanins and carotenoids, respectively. In addition, 88 unigenes were presumed to be involved in the chlorophyll metabolic pathway. Based on a comprehensive analysis of the pigment gene expression network, the mechanisms of leaf color were investigated. The massive accumulation of Cy led to its higher content and proportion than other pigments, which caused the redness of leaves. Yellow coloration was the result of the complete decomposition of chlorophyll pigments, the unmasking of carotenoid pigments, and a slight accumulation of Cy. CONCLUSIONS: This study provides a systematic analysis of color variations in the red maple. Moreover, mass sequence data obtained by deep sequencing will provide references for the controlled breeding of red maple.


Assuntos
Acer/fisiologia , Perfilação da Expressão Gênica/instrumentação , Pigmentação/genética , Transcriptoma , Acer/genética , Acer/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia
3.
PLoS One ; 14(6): e0218884, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31226157

RESUMO

In many woody dicot plant species, colder temperatures correlate with a greater degree of leaf dissection and with larger and more abundant leaf teeth (the serrated edges along margins). The measurement of site-mean characteristics of leaf size and shape (physiognomy), including leaf dissection and tooth morphology, has been an important paleoclimate tool for over a century. These physiognomic-based climate proxies require that all woody dicot plants at a site, regardless of species, change their leaf shape rapidly and predictably in response to temperature. Here we experimentally test these assumptions by growing five woody species in growth cabinets under two temperatures (17 and 25°C). In keeping with global site-based patterns, plants tend to develop more dissected leaves with more abundant and larger leaf teeth in the cool treatment. Overall, this upholds the assumption that leaf shape responds in a particular direction to temperature change. The assumption that leaf shape variables respond to temperature in the same way regardless of species did not hold because the responses varied by species. Leaf physiognomic models for inferring paleoclimate should take into account these species-specific responses.


Assuntos
Acer/crescimento & desenvolvimento , Betula/crescimento & desenvolvimento , Betulaceae/crescimento & desenvolvimento , Folhas de Planta/anatomia & histologia , Quercus/crescimento & desenvolvimento , Acer/anatomia & histologia , Betula/anatomia & histologia , Betulaceae/anatomia & histologia , Clima , Temperatura Baixa , Temperatura Alta , Quercus/anatomia & histologia , Sementes/crescimento & desenvolvimento , Especificidade da Espécie
4.
Chemosphere ; 229: 589-601, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31100630

RESUMO

The study aimed to evaluate the physiological mechanisms underlying differences in metals and metalloid uptake and tolerance of two tree species cultivated in mining waste material. Two-year old Acer platanoides L. and Tilia cordata Mill. were cultivated in mining sludge characterized by high pH, salinity and an extremely high concentration of As. Both species were able to develop leaves from leafless seedlings, however, their total biomass was greatly reduced in comparison to control plants, following the severe disturbances in chlorophyll content. Phytoextraction abilities were observed for T. cordata for Ba, Nb, Rb and Se, and phytostabilisation was stated for Pd, Ru, Sc and Sm for both species, Ba and Nd for A. platonoides and Be for T. cordata only. Metal exclusion was observed for the majority of detected elements indicating an intense limitation of metal transport to photosynthetic tissue. A diversified uptake of elements was accompanied by a species-specific pattern of physiological reaction during the cultivation in sludge. Organic ligands (glutatnione and low-molecular-weight organic acids) were suppressed in A. platanoides, and enhanced biosynthesis of phenolic compounds was observed for both species, being more pronounced in T. cordata. Despite its higher accumulation of key metabolites for plant reaction to oxidative stress, such as phenolic acids, flavonoids and organic ligands, T. cordata exhibited relatively lower tolerance to sludge, probably due to the increased uptake and translocation rate of toxic metal/loids to aerial organs and/or restricted accumulation of salicylic acid which is known to play a decisive role in mechanisms of plant tolerance.


Assuntos
Acer/crescimento & desenvolvimento , Mineração , Poluentes do Solo/farmacocinética , Tilia/crescimento & desenvolvimento , Acer/efeitos dos fármacos , Arsênico/análise , Arsênico/farmacocinética , Biodegradação Ambiental , Clorofila/metabolismo , Metais/farmacocinética , Metais/toxicidade , Fotossíntese/efeitos dos fármacos , Fotossíntese/fisiologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Especificidade da Espécie , Tilia/efeitos dos fármacos , Árvores/efeitos dos fármacos , Árvores/crescimento & desenvolvimento
5.
Sci Total Environ ; 663: 537-547, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30721845

RESUMO

Alkaline residuals, such as wood ash and lime mud generated from pulp and paper mills, could be recycled as liming agents in sugar maple (Acer saccharum Marsh.) forests affected by soil acidification. The objectives of this study were (1) to evaluate soil chemistry, in particular soil acidity, after the application of three alkaline residuals from the pulp and paper industry, and (2) to determine if these alkaline residuals altered soil greenhouse gas (GHG) emissions as a result of the change in soil pH or due to their chemical composition. Soil properties and GHG fluxes were monitored for two years after alkaline residuals were applied to six forest sites dominated by sugar maple in southeastern Quebec, Canada. Each site received six treatments: wood ash applied at 5, 10 and 20 t ha-1, lime mud (7.5 t ha-1), a mixture of slaker grits and green liquor sludge (7 t ha-1) and an unamended control. These treatments had acid-neutralizing power from 0 to 9 t ha-1. All alkaline residuals buffered soil acidity as a function of their neutralizing power, and more neutralization occurred in the forest floor layer than in the underlying mineral soil. In the forest floor, the alkaline residual treatments significantly increased pH by more than one unit, nearly doubled the base saturation, and reduced exchangeable acidity, Al and Fe concentrations compared to control plots. The CO2 and N2O fluxes were lower after application of alkaline residuals, and this was related to the soil pH increase and the type of alkaline residual applied. Lime mud was more effective at reducing GHG fluxes than other alkaline residuals. We conclude that these alkaline residuals can effectively counteract soil acidity in sugar maple forests without increasing soil GHG emissions, at least in the short term.


Assuntos
Poluição do Ar/prevenção & controle , Fertilizantes/análise , Agricultura Florestal/métodos , Florestas , Gases de Efeito Estufa/análise , Resíduos Industriais/análise , Solo/química , Acer/crescimento & desenvolvimento , Concentração de Íons de Hidrogênio , Indústrias , Papel , Quebeque
6.
Sci Total Environ ; 658: 1523-1530, 2019 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-30678010

RESUMO

Trees are important components of urban landscapes because of the ecosystem services they provide. However, the effects of urbanization, particularly high temperatures, can benefit chronic insect pests and threaten ecosystem services offered by urban trees. Urban forest fragments are an often-overlooked component of the greater urban forest which may help to mitigate the damaging effects of urbanization. Melanaspis tenebricosa (gloomy scale) is a common pest of Acer rubrum (red maple) that becomes more abundant because of the urban heat island effect. We conducted observational and manipulative field experiments to test the hypothesis that trees in urban forest fragments would be cooler than those in surrounding ornamental landscapes and would thus have fewer M. tenebricosa, particularly in a hot mid-latitude city. Trees in forest fragments were 1.3° cooler and had three orders of magnitude fewer M. tenebricosa than trees in ornamental landscapes in Raleigh, NC USA. However, there was no difference in M. tenebricosa density between forest and landscape trees in Newark, DE and Philadelphia, PA USA which are 3.95 degrees of latitude higher, and nearer to the northern range extent. Trees in landscapes and forest fragments did not differ in predawn water potential, a measure of water stress, but likely differed in soil composition and moisture. We used potted trees to control for these differences and found that M. tenebricosa density still increased three times more in landscapes than forests suggesting temperature and not tree stress is the dominant factor. Taken together our results indicate two things. First, that trees growing in urban forest fragments are buffered from a chronic urban tree pest due to lower temperatures. Second, that temperature-driven differences in M. tenebricosa density which we saw in Raleigh could predict future density of the pest in higher latitude cities as the climate warms.


Assuntos
Acer/fisiologia , Florestas , Aquecimento Global , Hemípteros/fisiologia , Árvores/fisiologia , Acer/crescimento & desenvolvimento , Animais , Cidades , Mudança Climática , Cadeia Alimentar , Herbivoria , Temperatura Alta , North Carolina , Dinâmica Populacional , Árvores/crescimento & desenvolvimento , Urbanização
7.
Equine Vet J ; 51(5): 701-704, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30629759

RESUMO

BACKGROUND: Several pasture management strategies have been proposed to avoid hypoglycin A (HGA) intoxication in horses, but their efficacy has never been investigated. OBJECTIVES: To evaluate the effect of mowing and herbicidal spraying on HGA content of sycamore seedlings and the presence of HGA in seeds and seedlings processed within haylage and silage. STUDY DESIGN: Experimental study. METHODS: Groups of seedlings were mowed (n = 6), sprayed with a dimethylamine-based (n = 2) or a picolinic acid-based herbicide (n = 1). Seedlings were collected before intervention, and at 48 h, 1 and 2 weeks after. Cut grass in the vicinity of mowed seedlings was collected pre-cutting and after 1 week. Seeds and seedling (n = 6) samples processed within haylage and silage were collected. HGA concentration in samples was measured using a validated LC-MS-based method. RESULTS: There was no significant decline in HGA content in either mowed or sprayed seedlings; indeed, mowing induced a temporary significant rise in HGA content of seedlings. HGA concentration increased significantly (albeit to low levels) in grass cut with the seedlings by 1 week. HGA was still present in sycamore material after 6-8 months storage within either hay or silage. MAIN LIMITATIONS: Restricted number of herbicide compounds tested. CONCLUSIONS: Neither mowing nor herbicidal spraying reduces HGA concentration in sycamore seedlings up to 2 weeks after intervention. Cross contamination is possible between grass and sycamore seedlings when mowed together. Mowing followed by collection of sycamore seedlings seems the current best option to avoid HGA toxicity in horses grazing contaminated pasture. Pastures contaminated with sycamore material should not be used to produce processed hay or silage as both seedlings and seeds present in the bales still pose a risk of intoxication.


Assuntos
Acer/química , Doenças dos Cavalos/induzido quimicamente , Hipoglicinas/metabolismo , Plântula/química , Acer/crescimento & desenvolvimento , Acer/metabolismo , Agricultura , Animais , Doenças dos Cavalos/prevenção & controle , Cavalos , Hipoglicinas/química , Hipoglicinas/toxicidade , Plântula/crescimento & desenvolvimento , Plântula/metabolismo
8.
Pest Manag Sci ; 75(7): 1971-1978, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30609246

RESUMO

BACKGROUND: The flatheaded appletree borer (Chrysobothris femorata Olivier) (FHAB) is a native pest of fruit, shade and nut trees throughout the United States. Use of cover crops is an effective pest management tool for some key insect pests in vegetable and cereal production systems, but its impact in woody ornamental production systems has not been investigated. The goal of this study was to evaluate the effectiveness of a winter cover crop for management of FHAB in nursery production. Red maple trees (Acer rubrum L.) grown under four treatment regimes (cover crop, cover crop + insecticide, bare row and bare row + insecticide) were evaluated for damage by FHAB and impact on tree growth parameters. RESULTS: The cover crop reduced FHAB damage, with results equivalent to standard imidacloprid treatments. The reduction in FHAB attacks in cover crop treatments may be due to microclimate changes at preferred oviposition sites, trunk camouflage or interference with access to oviposition sites. Tree growth was reduced in the cover crop treatments due to competition for resources. CONCLUSION: Physical blockage of oviposition sites by cover crops and subsequent microclimate changes protected against FHAB damage. Therefore, cover crops can be an alternative to chemical insecticides. © 2019 Society of Chemical Industry.


Assuntos
Acer/parasitologia , Besouros/fisiologia , Controle Biológico de Vetores/métodos , Acer/crescimento & desenvolvimento , Animais , Controle de Insetos/métodos , Inseticidas , Medicago , Neonicotinoides , Nitrocompostos , Oviposição , Triticum
9.
Tree Physiol ; 39(3): 417-426, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30239951

RESUMO

The introduction of species contributes to both ecological restoration and regional economics, while serving as a potential strategy to conserve species under rapid climate change. Despite an anticipated significant increase in temperature at high latitudes by the end of the 21st century, very few experimental migration trials have been conducted regarding large climate range changes. We employed a provenance trial by introducing a temperate sugar maple (Acer saccharum Marsh) of three provenances with a mean annual temperature of 3.0 °C in Manitoba, 4.2 °C in Quebec and 9.4 °C in Ontario, Canada, to 15.8 °C at an introduced site in subtropical China. We measured survival, growth, summer photosynthesis in the field and stress-resistance responses under a temperature gradient in growth chambers with first-year seedlings. We found that the Ontario provenance had the highest propensity for survival and growth, followed by the Quebec provenance, while the Manitoba provenance had the lowest. The photosynthetic parameters of the seedlings changed over time of the day, with the Ontario provenance having a higher photosynthesis rate and stomatal conductance than the Quebec and Manitoba provenances. Furthermore, the growth chamber results revealed that the Ontario provenance had the best physiological adjustment for self-protection from heat stress, followed by the Quebec and Manitoba provenances. Our results suggested that the change in climate range drove the survival and growth of introduced seedlings and that the tolerance to summer heat stress through physiological mechanisms was responsible for the success of species introduction, from a cold to a warm climate.


Assuntos
Acer/fisiologia , Temperatura Alta/efeitos adversos , Fotossíntese , Termotolerância , Acer/crescimento & desenvolvimento , Canadá , China , Mudança Climática , Espécies Introduzidas , Longevidade , Estações do Ano , Estresse Fisiológico
10.
Glob Chang Biol ; 25(2): 420-430, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30506555

RESUMO

Changes in growing season climate are often the foci of research exploring forest response to climate change. By contrast, little is known about tree growth response to projected declines in winter snowpack and increases in soil freezing in seasonally snow-covered forest ecosystems, despite extensive documentation of the importance of winter climate in mediating ecological processes. We conducted a 5-year snow-removal experiment whereby snow was removed for the first 4-5 weeks of winter in a northern hardwood forest at the Hubbard Brook Experimental Forest in New Hampshire, USA. Our results indicate that adverse impacts of reduced snowpack and increased soil freezing on the physiology of Acer saccharum (sugar maple), a dominant species across northern temperate forests, are accompanied by a 40 ± 3% reduction in aboveground woody biomass increment, averaged across the 6 years following the start of the experiment. Further, we find no indication of growth recovery 1 year after cessation of the experiment. Based on these findings, we integrate spatial modeling of snowpack depth with forest inventory data to develop a spatially explicit, regional-scale assessment of the vulnerability of forest aboveground growth to projected declines in snowpack depth and increased soil frost. These analyses indicate that nearly 65% of sugar maple basal area in the northeastern United States resides in areas that typically experience insulating snowpack. However, under the RCP 4.5 and 8.5 emissions scenarios, we project a 49%-95% reduction in forest area experiencing insulating snowpack by the year 2099 in the northeastern United States, leaving large areas of northern forest vulnerable to these changes in winter climate, particularly along the northern edge of the region. Our study demonstrates that research focusing on growing season climate alone overestimates the stimulatory effect of warming temperatures on tree and forest growth in seasonally snow-covered forests.


Assuntos
Florestas , Congelamento , Aquecimento Global , Neve , Solo , Árvores/crescimento & desenvolvimento , Acer/crescimento & desenvolvimento , Mudança Climática , New Hampshire
11.
Environ Entomol ; 47(4): 881-889, 2018 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-29771321

RESUMO

This project investigated associational interactions (associational resistance or susceptibility) between native and non-native trees commonly found in urban landscapes in the southeastern United States. Non-native plants offer limited ecological services because few native herbivore species are capable of feeding on them. In a 2-yr field study, abundance and species richness of caterpillars, plant damage, and herbivore natural enemies were evaluated in plots where a native red maple (Acer rubrum L. [Sapindales: Aceraceae]) was planted singly (no neighbors) or interplanted with either non-native non-congeneric crepe myrtles (Lagerstroemia indica L. [Myrtales: Lythraceae]), non-native congeneric Norway maples (Acer platanoides L. [Sapindales: Aceraceae]), or other red maples. Dryocampa rubicunda Fabricius (Lepidoptera: Saturniidae) accounted for most of the damage and caterpillar abundance. There were few significant differences between treatment groups in the establishment year of 2014, but in 2015 there was greater tree defoliation, caterpillar abundance, and caterpillar species richness when red maples were surrounded by crepe myrtles. We describe this as a biological fence effect in which the presence of crepe myrtle causes caterpillars to accumulate on the focal red maples over multiple generations. Red maples interplanted with Norway maple neighbors hosted an intermediate abundance and species richness of caterpillars compared to red maples interplanted with crepe myrtles and those with other red maples, indicating a spillover of herbivores to the related maple. No significant trends in insect natural enemy abundance or diversity between treatment groups were detected. These results highlight the necessity of considering plant associational interactions in context of species origin to alleviate pest outbreaks and develop sustainable landscape designs.


Assuntos
Acer/crescimento & desenvolvimento , Cadeia Alimentar , Herbivoria , Lagerstroemia/crescimento & desenvolvimento , Mariposas/fisiologia , Animais , Florida , Agricultura Florestal , Espécies Introduzidas , Larva/crescimento & desenvolvimento , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Árvores/crescimento & desenvolvimento
12.
J Plant Physiol ; 223: 72-83, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29550567

RESUMO

Approximately 20% of plant species, including silver maple (Acer saccharinum L.), produce seeds that are sensitive to desiccation, which is reflected in their poor storage potential and viability. In the search for a compound that can improve seed recalcitrance, freshly harvested seeds were soaked in either 2.5 mM reduced glutathione (GSH) or water and desiccated to comparable water levels of 55-20%. We examined the impact of a doubled endogenous level of glutathione on the seed germination capacity, the activity of enzymes involved in glutathione metabolism, the cell membrane components and integrity, reactive oxygen species, and ascorbate levels. GSH treatment resulted in slower dehydration and a higher germination capacity. The increased glutathione was mainly consumed by glutathione S-transferase, leading to more efficient detoxification, and by dehydroascorbate reductase (DHAR), accelerating the ascorbate regeneration. As a result, the cellular environment became more reduced, and protection of the membrane structures was enhanced. The ameliorated membrane integrity was manifested via a lower electrolyte leakage and a lower lipid peroxide level despite the higher level of hydrogen peroxide (H2O2) detected in the GSH-treated seeds. The degradation of phospholipids (PLs) was less intense and related to the phosphatidylinositol (PI) level, which is the precursor of the phospholipase D cofactor, whereas in water-soaked seeds, PL degradation was promoted by H2O2. The germination capacity of the dehydrated seeds depended primarily on the level of H2O2, lipid hydroxyperoxides, electrolyte leakage, GSH, the half-cell reduction potential of glutathione, PI, and the activity of DHAR and γ-glutamylcysteine synthetase. Interestingly, H2O2 affected all of the parameters. The germination of GSH-boosted seeds was strongly impacted by the pool of ascorbate, the half-cell reduction potential of ascorbate, and the glutathione peroxidase activity. In general, germination was DHAR activity-dependent. A strong negative correlation was detected in the water-soaked seeds, whereas a strong positive correlation was detected in the GSH-treated seeds. The enhanced level of glutathione likely improved the efficiency of the ascorbate-glutathione cycle, confirming its effect on seed germinability after dehydration.


Assuntos
Acer/crescimento & desenvolvimento , Acer/metabolismo , Dessecação , Germinação/efeitos dos fármacos , Glutationa/metabolismo , Sementes/crescimento & desenvolvimento , Ácido Ascórbico/metabolismo , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos , Água/metabolismo
13.
Int J Biometeorol ; 62(6): 949-959, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29404687

RESUMO

It has been widely reported that the urban environment alters leaf and flowering phenophases; however, it remains unclear if land pavement is correlated with these alterations. In this paper, two popular deciduous urban trees in northern China, ash (Fraxinus chinensis) and maple (Acer truncatum), were planted in pervious and impervious pavements at three spacings (0.5 m × 0.5 m, 1.0 m × 1.0 m, and 2.0 m × 2.0 m apart). The beginning and end dates of the processes of leaf budburst and senescence were recorded in spring and fall of 2015, respectively. The results show that leaf budburst and senescence were significantly advanced in pavement compared to non-pavement lands. The date of full leaf budburst was earlier by 0.7-9.3 days for ash and by 0.3-2.3 days for maple under pavements than non-pavements, respectively. As tree spacing increases, the advanced days of leaf budburst became longer. Our results clearly indicate that alteration of leaf phenophases is attributed to land pavement, which should be taken into consideration in urban planning and urban plant management.


Assuntos
Acer/crescimento & desenvolvimento , Fraxinus/crescimento & desenvolvimento , Microclima , Folhas de Planta/crescimento & desenvolvimento , China , Planejamento de Cidades , Manufaturas , Estações do Ano , Temperatura , Urbanização
14.
BMC Res Notes ; 10(1): 369, 2017 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-28789702

RESUMO

BACKGROUND: Sugar maple (Acer saccharum Marsh.) is a hardwood tree species native to northeastern North America and economically valued for its wood and sap. Yet, few molecular genetic resources have been developed for this species to date. Microsatellite markers have been a useful tool in population genetics, e.g., to monitor genetic variation and to analyze gene flow patterns. The objective of this study is to develop a reference transcriptome and microsatellite markers in sugar maple. FINDINGS: A set of 117,861 putative unique transcripts were assembled using 29.2 Gb of RNA sequencing data derived from different tissues and stress treatments. From this set of sequences a total of 1068 microsatellite motifs were identified. Out of 58 genic microsatellite markers tested on a population of 47 sugar maple trees in upper Michigan, 22 amplified well, of which 16 were polymorphic and 6 were monomorphic. Values for expected heterozygosity varied from 0.224 to 0.726 for individual loci. Of the 16 polymorphic markers, 15 exhibited transferability to other Acer L. species. CONCLUSIONS: Genic microsatellite markers can be applied to analyze genetic variation in potentially adaptive genes relative to genomic reference markers as a basis for the management of sugar maple genetic resources in the face of climate change.


Assuntos
Acer/genética , Genoma de Planta , Repetições de Microssatélites , Folhas de Planta/genética , Transcriptoma , Acer/crescimento & desenvolvimento , Mudança Climática , Fluxo Gênico , Variação Genética , Heterozigoto , Sequenciamento de Nucleotídeos em Larga Escala , Folhas de Planta/crescimento & desenvolvimento , Árvores
15.
Tree Physiol ; 37(10): 1337-1351, 2017 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-28338906

RESUMO

A key trait used in canopy and ecosystem function modeling, leaf mass per area (LMA), is influenced by changes in both leaf thickness and leaf density (LMA = Thickness × Density). In tall trees, LMA is understood to increase with height through two primary mechanisms: (i) increasing palisade layer thickness (and thus leaf thickness) in response to light and/or (ii) reduced cell expansion and intercellular air space in response to hydrostatic constraints, leading to increased leaf density. Our objective was to investigate within-canopy gradients in leaf anatomical traits in order to understand environmental factors that influence leaf morphology in a sugar maple (Acer saccharum Marshall) forest canopy. We teased apart the effects of light and height on anatomical traits by sampling at exposed and closed canopies that had different light conditions at similar heights. As expected, palisade layer thickness responded strongly to cumulative light exposure. Mesophyll porosity, however, was weakly and negatively correlated with light and height (i.e., hydrostatic gradients). Reduced mesophyll porosity was not likely caused by limitations on cell expansion; in fact, epidermal cell width increased with height. Palisade layer thickness was better related to LMA, leaf density and leaf thickness than was mesophyll porosity. Vein diameter and fraction of vascular tissue also increased with height and LMA, density and thickness, revealing that greater investment in vascular and support tissue may be a third mechanism for increased LMA with height. Overall, decreasing mesophyll porosity with height was likely due to palisade cells expanding into the available air space and also greater investments in vascular and support tissue, rather than a reduction of cell expansion due to hydrostatic constraints. Our results provide evidence that light influences both palisade layer thickness and mesophyll porosity and indicate that hydrostatic gradients influence leaf vascular and support tissues in mature Acer saccharum trees.


Assuntos
Acer/anatomia & histologia , Acer/fisiologia , Acer/crescimento & desenvolvimento , Luz , Fotossíntese , Folhas de Planta/anatomia & histologia , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Água/fisiologia
16.
Tree Physiol ; 37(1): 47-59, 2017 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-28173593

RESUMO

A useful approach to monitor tree response to climate change and environmental extremes is the recording of long-term time series of stem radial variations obtained with precision dendrometers. Here, we study the impact of environmental stress on seasonal growth dynamics and productivity of yellow birch (Betula alleghaniensis Britton) and sugar maple (Acer saccharum Marsh.) in the Great Lakes, St Lawrence forest region of Ontario. Specifically, we research the effects of a spring heat wave in 2010, and a summer drought in 2012 that occurred during the 2005­14 study period. We evaluated both growth phenology (onset, cessation, duration of radial growth, time of maximum daily growth rate) and productivity (monthly and seasonal average growth rates, maximum daily growth rate, tree-ring width) and tested for differences and interactions among species and years. Productivity of sugar maple was drastically compromised by a 3-day spring heat wave in 2010 as indicated by low growth rates, very early growth cessation and a lagged growth onset in the following year. Sugar maple also responded more sensitively than yellow birch to a prolonged drought period in July 2012, but final tree-ring width was not significantly reduced due to positive responses to above-average temperatures in the preceding spring. We conclude that sugar maple, a species that currently dominates northern hardwood forests, is vulnerable to heat wave disturbances during leaf expansion, which might occur more frequently under anticipated climate change.


Assuntos
Acer/crescimento & desenvolvimento , Betula/crescimento & desenvolvimento , Secas , Temperatura Alta , Folhas de Planta/crescimento & desenvolvimento , Árvores/crescimento & desenvolvimento , Mudança Climática , Florestas , Ontário , Estações do Ano , Estresse Fisiológico
17.
PLoS One ; 12(2): e0171321, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28234921

RESUMO

Nitrogen and phosphorous are critical determinants of plant growth and productivity, and both plant growth and root morphology are important parameters for evaluating the effects of supplied nutrients. Previous work has shown that the growth of Acer mono seedlings is retarded under nursery conditions; we applied different levels of N (0, 5, 10, and 15 g plant-1) and P (0, 4, 6 and 8 g plant-1) fertilizer to investigate the effects of fertilization on the growth and root morphology of four-year-old seedlings in the field. Our results indicated that both N and P application significantly affected plant height, root collar diameter, chlorophyll content, and root morphology. Among the nutrient levels, 10 g N and 8 g P were found to yield maximum growth, and the maximum values of plant height, root collar diameter, chlorophyll content, and root morphology were obtained when 10 g N and 8 g P were used together. Therefore, the present study demonstrates that optimum levels of N and P can be used to improve seedling health and growth during the nursery period.


Assuntos
Acer/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Acer/metabolismo , Clorofila/metabolismo , Fertilizantes , Nitrogênio/química , Fósforo/química , Raízes de Plantas/metabolismo , Plântula/metabolismo , Solo/química
18.
Ecology ; 97(12): 3359-3368, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27912011

RESUMO

Snow cover is projected to decline during the next century in many ecosystems that currently experience a seasonal snowpack. Because snow insulates soils from frigid winter air temperatures, soils are expected to become colder and experience more winter soil freeze-thaw cycles as snow cover continues to decline. Tree roots are adversely affected by snowpack reduction, but whether loss of snow will affect root-microbe interactions remains largely unknown. The objective of this study was to distinguish and attribute direct (e.g., winter snow- and/or soil frost-mediated) vs. indirect (e.g., root-mediated) effects of winter climate change on microbial biomass, the potential activity of microbial exoenzymes, and net N mineralization and nitrification rates. Soil cores were incubated in situ in nylon mesh that either allowed roots to grow into the soil core (2 mm pore size) or excluded root ingrowth (50 µm pore size) for up to 29 months along a natural winter climate gradient at Hubbard Brook Experimental Forest, NH (USA). Microbial biomass did not differ among ingrowth or exclusion cores. Across sampling dates, the potential activities of cellobiohydrolase, phenol oxidase, and peroxidase, and net N mineralization rates were more strongly related to soil volumetric water content (P < 0.05; R2  = 0.25-0.46) than to root biomass, snow or soil frost, or winter soil temperature (R2  < 0.10). Root ingrowth was positively related to soil frost (P < 0.01; R2  = 0.28), suggesting that trees compensate for overwinter root mortality caused by soil freezing by re-allocating resources towards root production. At the sites with the deepest snow cover, root ingrowth reduced nitrification rates by 30% (P < 0.01), showing that tree roots exert significant influence over nitrification, which declines with reduced snow cover. If soil freezing intensifies over time, then greater compensatory root growth may reduce nitrification rates directly via plant-microbe N competition and indirectly through a negative feedback on soil moisture, resulting in lower N availability to trees in northern hardwood forests.


Assuntos
Acer/microbiologia , Florestas , Raízes de Plantas/microbiologia , Neve , Acer/crescimento & desenvolvimento , Nitrificação , Raízes de Plantas/crescimento & desenvolvimento
19.
Environ Entomol ; 45(4): 1040-8, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27412195

RESUMO

Exotic ambrosia beetles are among the most damaging pests of trees grown in nurseries. The primary pests Xylosandrus crassiusculus Motschulsky and Xylosandrus germanus Blandford use ethanol to locate vulnerable trees. Research, primarily with X. germanus, has shown that flood-stressed trees emit ethanol and are preferentially attacked by ambrosia beetles. Our goal was to develop a media (also called potting soil) moisture threshold as an integrated pest management (IPM) tactic and assess grower practices that lead to ambrosia beetle attacks. Flooded Cornus florida L., Cornus kousa Burg., and Magnolia grandiflora L. trees incurred more attacks than unflooded trees that were not attacked. To determine optimal media moisture levels, we grew flood-tolerant Acer rubrum L. and flood-intolerant C. florida in containers with 10, 30, 50, 70, or 90% media moisture. No flooded or unflooded A. rubrum were attacked. However, C. florida grown in 70 or 90% moisture were attacked and died, whereas trees at 30 and 50% moisture were not attacked. Thus, we suggest an upper moisture threshold of 50% when growing C. florida and other flood-intolerant trees. However, during peak ambrosia beetle flight activity in spring 2013 and 2014, we found that media moisture levels in commercial nurseries were often between 50 and 90%. Implementing a media moisture threshold, as a new IPM tool, could reduce ambrosia beetle attacks and the need for insecticide applications, which is currently the only available management tactic. Future research should focus on how changes in substrates, irrigation, and other practices could help growers meet this threshold.


Assuntos
Inundações , Agricultura Florestal/métodos , Herbivoria , Árvores/fisiologia , Gorgulhos/fisiologia , Acer/crescimento & desenvolvimento , Acer/fisiologia , Animais , Cornus/crescimento & desenvolvimento , Cornus/fisiologia , Etanol/metabolismo , Magnolia/crescimento & desenvolvimento , Magnolia/fisiologia , North Carolina , Distribuição Aleatória , Árvores/crescimento & desenvolvimento
20.
PLoS One ; 11(7): e0160238, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27467130

RESUMO

Ecological communities are structured in response to spatial and temporal variation of numerous factors, including edaphic conditions, biotic interactions, climatic patterns and disturbance regimes. Widespread anthropogenic factors such as timber harvesting can create long-lasting impacts, obscuring the relationship between community structure and environmental conditions. Minimally impacted systems such as old-growth forests can serve as a useful ecological baseline for predicting long-term compositional shifts. We utilized decadal tree species sampling data (1979-2010) divided into three strata (understory, midstory, overstory) to examine temporal changes in relative abundances and spatial distributions of dominant taxa, as well as overall shifts in community composition, in a relatively pristine Appalachian old-growth forest in eastern Kentucky, USA. Quercus and Carya species persisted mainly as mature canopy trees with decreasing juvenile recruitment, especially in mesic areas. In contrast, Acer, Fagus, and other mesophytic species were abundant and spatially widespread in subcanopy layers suggesting these species are more likely to recruit in gap-scale canopy openings. In the overstory, mesophytic species were spatially restricted to lower and mid-slope mesic habitats. Temporal changes in community composition were most evident in the understory and tended to be greater in mesic areas, a trend seemingly driven by recruitment failure among xerophytic species. In subcanopy vegetation we discovered a loss of distinction through time among the ecological community designations established following the 1979 survey (Chestnut oak, Mixed mesophytic, and Beech). The overstory was more stable through time, suggesting a storage effect where long-lived trees have maintained a particular community composition through time in areas where regeneration opportunities are minimal under current environmental conditions. Overall, sitewide canopy succession is occurring slowly in the absence of major disturbance, and topography-driven environmental variation appears to have an important local-scale filtering effect on communities.


Assuntos
Acer/crescimento & desenvolvimento , Florestas , Quercus/crescimento & desenvolvimento , Ecossistema
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