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1.
Plant Biol (Stuttg) ; 22(1): 106-112, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31433536

RESUMO

Several Cerrado tree species have traits and structures that protect from fires. The effectiveness of a trait depends on the fire regime, especially the frequency. We used Vochysia elliptica, a common Cerrado tree, as a model to test whether different fire frequencies alter crown architecture and flower, fruit and seed production. We analysed the effect of fire on the production of inflorescences, fruits and seeds, as well as seed germination and tree architecture of 20 trees in each of three plots of a long-term ecological experiment managed with different fire regimes: burned every 2 years (B), burned every 4 years (Q) in mid-dry season and an area protected from fire (C). We found a large negative effect of fire frequency on crown architecture and on flower and fruit production. Trees in C and Q had significantly more main branches and a larger crown area than trees in B. At its peak, a tree in C was expected to produce 2.4 times more inflorescences than Q, and 15.5 times more than B, with similar magnitudes for fruits. Sixty per cent of trees in B and 10% in Q produced no fruits. The differences in architecture might explain the reduction in sexual reproduction due to a smaller physical space to produce flowers at the branch apices. Resource limitation due to plant investment to replace burned vegetative parts may also decrease sexual reproduction. Our results indicate potentially severe consequences of high fire frequencies for population dynamics and species persistence in Cerrado communities.


Assuntos
Fogo , Pradaria , Árvores , Dinâmica Populacional , Sementes/fisiologia , Árvores/anatomia & histologia , Árvores/fisiologia
3.
BMC Evol Biol ; 19(1): 231, 2019 12 26.
Artigo em Inglês | MEDLINE | ID: mdl-31878866

RESUMO

BACKGROUND: Natural selection on fitness-related traits can be temporally heterogeneous among populations. As climate changes, understanding population-level responses is of scientific and practical importance. We examined 18 phenotypic traits associated with phenology, biomass, and ecophysiology in 403 individuals of natural Populus trichocarpa populations, growing in a common garden. RESULTS: Compared with tree origin settings, propagules likely underwent drought exposures in the common garden due to significantly low rainfall during the years of measurement. All study traits showed population differentiation reflecting adaptive responses due to local genetic adaptation. Phenology and biomass traits were strongly under selection and showed plastic responses between years, co-varying with latitude. While phenological events (e.g., bud set and growth period) and biomass were under positive directional selection, post-bud set period, particularly from final bud set to the onset of leaf drop, was selected against. With one exception to water-use efficiency, ecophysiology traits were under negative directional selection. Moreover, extended phenological events jointly evolved with source niches under increased temperature and decreased rainfall exposures. High biomass coevolved with climatic niches of high temperature; low rainfall promoted high photosynthetic rates evolution. CONCLUSIONS: This work underpins that P. trichocarpa is likely to experience increased fitness (height gain) by evolving toward extended bud set and growth period, abbreviated post-bud set period, and increased drought resistance, potentially constituting a powerful mechanism for long-lived tree species in surviving unpredictably environmental extremes (e.g., drought).


Assuntos
Mudança Climática , Populus/genética , Aclimatação , Adaptação Fisiológica , Biomassa , Evolução Molecular , Jardins , Fotossíntese , Folhas de Planta , Populus/fisiologia , Seleção Genética , Árvores/genética , Árvores/fisiologia
4.
Nat Commun ; 10(1): 4590, 2019 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-31611554

RESUMO

Intact forests provide diverse and irreplaceable ecosystem services that are critical to human well-being, such as carbon storage to mitigate climate change. However, the ecosystem functions that underpin these services are highly dependent on the woody vegetation-animal interactions occurring within forests. While vertebrate defaunation is of growing policy concern, the effects of vertebrate loss on natural forest regeneration have yet to be quantified globally. Here we conduct a meta-analysis to assess the direction and magnitude of defaunation impacts on forests. We demonstrate that real-world defaunation caused by hunting and habitat fragmentation leads to reduced forest regeneration, although manipulation experiments provide contrasting findings. The extirpation of primates and birds cause the greatest declines in forest regeneration, emphasising their key role in maintaining carbon stores, and the need for national and international climate change and conservation strategies to protect forests from defaunation fronts as well as deforestation fronts.


Assuntos
Biodiversidade , Conservação dos Recursos Naturais/métodos , Ecossistema , Florestas , Árvores/fisiologia , Animais , Biomassa , Aves/fisiologia , Carbono/metabolismo , Mudança Climática , Humanos , Modelos Biológicos , Primatas/fisiologia , Árvores/classificação , Vertebrados/fisiologia
5.
Nat Commun ; 10(1): 4757, 2019 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-31628336

RESUMO

Recent progress in remote sensing provides much-needed, large-scale spatio-temporal information on habitat structures important for biodiversity conservation. Here we examine the potential of a newly launched satellite-borne radar system (Sentinel-1) to map the biodiversity of twelve taxa across five temperate forest regions in central Europe. We show that the sensitivity of radar to habitat structure is similar to that of airborne laser scanning (ALS), the current gold standard in the measurement of forest structure. Our models of different facets of biodiversity reveal that radar performs as well as ALS; median R² over twelve taxa by ALS and radar are 0.51 and 0.57 respectively for the first non-metric multidimensional scaling axes representing assemblage composition. We further demonstrate the promising predictive ability of radar-derived data with external validation based on the species composition of birds and saproxylic beetles. Establishing new area-wide biodiversity monitoring by remote sensing will require the coupling of radar data to stratified and standardized collected local species data.


Assuntos
Biodiversidade , Florestas , Radar , Tecnologia de Sensoriamento Remoto/métodos , Árvores/fisiologia , Animais , Aves/classificação , Aves/fisiologia , Besouros/classificação , Besouros/fisiologia , Conservação dos Recursos Naturais/métodos , Modelos Teóricos , Reprodutibilidade dos Testes , Análise Espaço-Temporal , Árvores/classificação
6.
J Plant Res ; 132(6): 789-811, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31628563

RESUMO

The study aimed to assess response of juvenile progeny of seven forest tree species, Pinus sylvestris, Picea abies, Betula pendula, Alnus glutinosa, Populus tremula, Quercus robur and Fraxinus excelsior, and their populations to different combinations of climate change-related multiple stressors, simulated in a phytotron under elevated CO2 concentration: (1) heat + elevated humidity (HW); (2) heat + frost + drought (HFD); (3) heat + elevated humidity + increased UV-B radiation doses + elevated ozone concentration (HWUO); and (4) heat + frost + drought + increased UV-B radiation doses + elevated ozone concentration (HFDUO). Effects of the complex treatments, species and species-by-treatment interaction were highly significant in most of the growth, physiological and biochemical traits studied, indicating general and species-specific responses to the applied treatments. For deciduous trees, height increment was much higher under HW treatment than in ambient conditions (control) indicating a positive effect of elevated temperature and better water and CO2 availability. HFD treatment caused reduction of height increment in comparison to HW treatment in most species except for Q. robur and F. excelsior which benefited from lower humidity. Treatments HWUO and HFDUO have caused substantial damages to leaves in fast growing deciduous P. tremula, A. glutinosa and B. pendula, and resulted in their lower height increment than in HW treatment, although it was the same or even higher than that in the control. Rates of photosynthesis in most of the tree species were greatest in HFD treatment. A lower photosynthetic rate (compared to control) was observed in B. pendula, P. tremula and F. excelsior in HW treatment, and in most species-in HWUO treatment. Compared to control, intrinsic water use efficiency in all treatments was significantly lower in P. tremula, A. glutinosa and F. excelsior and higher in conifers P. sylvestris and P. abies. Significant population-by-treatment interactions found for most traits showed variation in response of populations, implying that this reflects adaptive potential of each tree species. The observed responses may not always be considered as adaptive as deteriorating growth of some populations or species may lead to loss of their competitiveness thus compromising regeneration and natural successions.


Assuntos
Mudança Climática , Secas , Temperatura Alta/efeitos adversos , Ozônio/efeitos adversos , Árvores/fisiologia , Raios Ultravioleta , Tempo (Meteorologia) , Dióxido de Carbono/análise , Especificidade da Espécie
7.
Plant Physiol Biochem ; 144: 118-126, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31563092

RESUMO

As nitrogen deposition increases, acid rain is gradually shifting from sulfuric acid rain (SAR) to nitric acid rain (NAR). Acid rain can severely affect plant growth, damage ecosystems, and reduce biodiversity. Thus, a shift in acid rain type presents another challenge to the conservation of endangered plant species. We investigated the effect of three acid rain types (SAR, mixed acid rain [MAR], and NAR) and pH on the growth of an endangered Chinese endemic tree, Horsfieldia hainanensis Merr., using simulated rain in a greenhouse environment. Over nine months, growth indices, chlorophyll content, antioxidant enzyme activity, malondialdehyde content, and chlorophyll fluorescence parameters were investigated for treated and control saplings. The results indicated that at a pH of 5.6, H. hainanensis could adapt to SAR and MAR, but NAR inhibited below-ground growth. At a pH of 2.5 and 4.0, SAR inhibited stem and leaf biomass accumulation, whereas NAR inhibited root biomass accumulation and altered root morphology. MAR had intermediary effects between those of SAR and NAR. Adverse effects on leaf physiology were reduced as the rain type shifted from SAR to NAR; however, roots were increasingly adversely affected. Our results suggest that conservation efforts for H. hainanensis should shift from an above-ground to a below-ground focus as acid rain transitions toward NAR.


Assuntos
Chuva Ácida/toxicidade , Myristicaceae/fisiologia , Ácido Nítrico/toxicidade , Ácidos Sulfúricos/toxicidade , Árvores/fisiologia , China , Ecossistema , Concentração de Íons de Hidrogênio , Myristicaceae/efeitos dos fármacos , Árvores/efeitos dos fármacos
8.
Nat Commun ; 10(1): 4385, 2019 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-31558795

RESUMO

Forest mortality is accelerating due to climate change and the largest trees may be at the greatest risk, threatening critical ecological, economic, and social benefits. Here, we combine high-resolution airborne LiDAR and optical data to track tree-level mortality rates for ~2 million trees in California over 8 years, showing that tree height is the strongest predictor of mortality during extreme drought. Large trees die at twice the rate of small trees and environmental gradients of temperature, water, and competition control the intensity of the height-mortality relationship. These findings suggest that future persistent drought may cause widespread mortality of the largest trees on Earth.


Assuntos
Secas , Florestas , Estresse Fisiológico/fisiologia , Árvores/fisiologia , Adaptação Fisiológica/fisiologia , California , Temperatura Ambiente , Árvores/anatomia & histologia , Água
9.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2614-2620, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418185

RESUMO

Three typical plant communities (evergreen broad-leaved forest at low-altitude 1100 m, evergreen and deciduous mixed broad-leaved forest at mid-altitude 1500 m, and evergreen conife-rous and broad-leaved mixed forest at high-altitude 1900 m) in Maoer Mountain, Guangxi, China were surveyed along an altitude gradient. We measured the tree layer plant architecture and environmental factors, to analyze the variation of plant architecture traits among the three communities and its influencing factors. The results showed that the tree layer canopy area, basal diameter at 45 cm height, diameter at breast height (DBH), and leaf convergence increased with increasing altitude, whereas tree height, branch height, and canopy thickness first increased and then decreased. Horizontal branches occurred more often in communities at lower altitude , less frequent at high altitude, and the least frequent in middle altitude communities. Correlations among tree layer plant architecture traits were stronger in the mid-altitude community than that in the other altitude communities. Results from the redundancy analysis showed that soil organic matter and total solar radiation were the main factors driving the variation of plant architecture traits in the tree layers, accounting for 39.6% and 23.9% of the total variation, respectively. Soil organic matter had a greater positive impact on canopy area and branch height, whereas total solar radiation was more influential on the DBH and 45 cm basal diameter. In conclusion, tree layer architecture of communities along the altitude gradient in Maoer Mountain was divergent, with soil organic matter and total solar radiation as the main driving forces.


Assuntos
Altitude , Árvores/fisiologia , China , Florestas , Plantas , Solo , Árvores/anatomia & histologia
10.
Sci Total Environ ; 687: 1065-1072, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31412444

RESUMO

We analyzed the Italian National Forest Inventory data set to evaluate the interdependence of forest productivity, tree species richness (used to indicate biodiversity), climate, and soil factors. We tested the hypotheses that the relationship between biodiversity and forest productivity is positive and significant for all forests in Italy and whether the relationship is the same for forests growing in the temperate and Mediterranean bioclimatic domains (regions) of Italy. We used generalized additive models to explore the univariate response curves for the data and then performed structural equation modeling (SEM) and multi-group SEM analyses to evaluate the relationship between biodiversity and productivity. We found that the SEM model for the entire dataset explained about 60% of the variation in forest productivity. In addition, the variation associated with species richness was greater than variation due to climatic factors and the variation in climate factors was greater than the variation in soil factors (all relative to their contributions to productivity). The multi-group SEM showed a more predominant effect of biodiversity and climate on productivity in Mediterranean compared to temperate forests. In both cases, we observed a moderate effect of soil (factors) on forest productivity. Our results support the hypothesis that increasing tree diversity in forests could help reduce the effects of climate warming and enhance ecosystem productivity in the Mediterranean region.


Assuntos
Biodiversidade , Clima , Florestas , Árvores/classificação , Biomassa , Mudança Climática , Ecossistema , Monitoramento Ambiental , Itália , Região do Mediterrâneo , Árvores/fisiologia
11.
An Acad Bras Cienc ; 91(suppl 3): e20180768, 2019 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-31460592

RESUMO

As a focus for conservation efforts, biodiversity has received increased attention in the last fifty years. Searching for patterns in biodiversity, researchers have suggested studies including: ecological communities, cladistics classifications, hierarchical compositions of different levels of organization, and groups of taxonomically related species. Here, we propose that the study of the biodiversity of interactions may present a new perspective in the efforts to conserve biodiversity, especially in endangered ecosystems like the tropical savannas. We suggest that Cerrado, like other tropical savannas, is a particularly important ecosystem in which we can direct efforts to explain what determines the major part of variation in the outcomes of species interactions.


Assuntos
Formigas/fisiologia , Biodiversidade , Conservação dos Recursos Naturais , Ecossistema , Árvores/fisiologia , Animais , Brasil
12.
BMC Plant Biol ; 19(1): 367, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31429697

RESUMO

BACKGROUND: Adaptation to abiotic stresses is crucial for the survival of perennial plants in a natural environment. However, very little is known about the underlying mechanisms. Here, we adopted a liquid culture system to investigate plant adaptation to repeated salt stress in Populus trees. RESULTS: We first evaluated phenotypic responses and found that plants exhibit better stress tolerance after pre-treatment of salt stress. Time-course RNA sequencing (RNA-seq) was then performed to profile changes in gene expression over 12 h of salt treatments. Analysis of differentially expressed genes (DEGs) indicated that significant transcriptional reprogramming and adaptation to repeated salt treatment occurred. Clustering analysis identified two modules of co-expressed genes that were potentially critical for repeated salt stress adaptation, and one key module for salt stress response in general. Gene Ontology (GO) enrichment analysis identified pathways including hormone signaling, cell wall biosynthesis and modification, negative regulation of growth, and epigenetic regulation to be highly enriched in these gene modules. CONCLUSIONS: This study illustrates phenotypic and transcriptional adaptation of Populus trees to salt stress, revealing novel gene modules which are potentially critical for responding and adapting to salt stress.


Assuntos
Adaptação Fisiológica/genética , Regulação da Expressão Gênica de Plantas , Populus/genética , Estresse Salino/genética , Transcrição Genética , Ontologia Genética , Redes Reguladoras de Genes , Genoma de Planta , Fenótipo , Populus/fisiologia , RNA de Plantas , Análise de Sequência de RNA , Transcriptoma , Árvores/genética , Árvores/fisiologia
13.
PLoS One ; 14(7): e0218741, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31291260

RESUMO

BACKGROUND: Many studies have analysed the effect of browsing by large herbivores on tree species but far fewer studies have studied their effect on understorey shrubs and herbs. Moreover, while many studies have shown that forest features and management intensity strongly influence understorey vegetation, the influence of such variation on the effect of large-herbivore exclusion is not known. THIS STUDY: In this study, we analysed changes of species richness, Shannon diversity, evenness and cover of understorey herbs and shrubs after excluding large herbivores for seven years on 147 forest sites, differing in management intensity and forest features, in three regions of Germany (Schwäbische Alb, Hainich-Dün, Schorfheide-Chorin). Further, we studied how the effect of large-herbivore exclusion on understorey vegetation was influenced by forest management intensity and several forest features. RESULTS: As expected, exclusion of large herbivores resulted in highly variable results. Nevertheless, we found that large-herbivore exclusion significantly increased cover and Shannon diversity of shrub communities, while it did not affect herb communities. Forest management intensity did not influence the effect of large-herbivore exclusion while some forest features, most often relative conifer cover, did. In forests with high relative conifer cover, large-herbivore exclusion decreased species richness and cover of herbs and increased Shannon diversity of herbs and shrubs, while in forests with low relative conifer cover large-herbivore exclusion increased species richness and cover of herbs, and decreased Shannon diversity of herbs and shrubs. CONCLUSION: We suggest that browsing by large herbivores should be included when studying understorey shrub communities, however when studying understorey herb communities the effects of browsing are less general and depend on forest features.


Assuntos
Cadeia Alimentar , Poaceae/fisiologia , Traqueófitas/fisiologia , Árvores/fisiologia , Biodiversidade , Agricultura Florestal/métodos , Florestas , Alemanha , Herbivoria/fisiologia
14.
PLoS One ; 14(7): e0219270, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31291307

RESUMO

Land use and land cover change induced by large scale ecological restoration programs has a significant impact on the terrestrial ecosystem carbon cycle, especially on the net primary productivity (NPP) in arid and semi-arid regions. This study investigated the change in NPP caused by the large-scale ecological restoration in the Chinese Loess Plateau (LPR) region from 1986 to 2015 based on land cover datasets and NPP calculated using the Carnegie-Ames-Stanford Approach model. The results indicated that the annual total NPP exhibited a significant uptrend (P < 0.01) throughout the whole vegetation restoration region during the last 30 years, with an annual increase of 0.137 Tg C. A significant abrupt change was detected in 2006 for the annual total NPP series. Over half of the restoration region showed an increase in NPP in the past three decades, however, about 30~40% of the vegetation restoration region exhibited NPP loss before 2006, but subsequently NPP loss was found in only approximately 20% of the study region. Overall, the increase in NPP attributed to the vegetation restoration reached 51.14 Tg C in the past three decades, indicating that these large-scale vegetation restoration programs increased the carbon sequestration capacity of terrestrial ecosystems in the Loess Plateau. The findings of this study improve our understanding of the effects of the green campaign on terrestrial ecosystems.


Assuntos
Agricultura , Ciclo do Carbono , Mudança Climática , Ecossistema , Sequestro de Carbono , China , Clima Desértico , Florestas , Pradaria , Humanos , Modelos Teóricos , Árvores/metabolismo , Árvores/fisiologia
15.
PLoS One ; 14(6): e0217198, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31188862

RESUMO

Insect pollinator communities are thought to transition from bee-dominated communities at low elevations to fly-dominated communities at high elevations. We predicted that increased tree canopy cover and a subsequent decrease in meadows and flowering plants would limit bees but not flies at higher elevations. We tested and supported this prediction by examining changes in both abundance and species richness for 128 bee species and 96 fly species at key points along an elevational gradient in Northern Arizona represented by distinct vegetation life zones. In addition to an increase in fly species and abundance relative to bees with increasing elevation, there were changes in community structure). To better understand factors that might influence this transition we examined how tree canopy cover changed along the elevational gradient and how this influenced the change in insect pollinator communities. While bee communities were progressively divergent between forest and meadow habitats with increasing elevation and tree canopy cover, there was no significant pattern with flies between meadow and forest habitats. However, fly abundance did increase with increasing elevation relative to bees. Along a comparable elevational gradient on an adjacent mountain with no tree canopy cover (i.e., a fire burned mountain), the bee-to-fly transition did not occur; bees persisted as the dominant pollinator into the highest life zone. This suggests that tree canopy cover can in part explain the transition from bee-to fly-dominated communities. In conclusion, this is the first study in North America to document a bee-fly transition for both abundance and species richness and show that tree canopy cover may play a role in determining pollinator community composition, by restricting bees to open meadow habitats.


Assuntos
Abelhas/fisiologia , Dípteros/fisiologia , Árvores/fisiologia , Animais , Arizona , Florestas , Polinização , Dinâmica Populacional
17.
Sci Total Environ ; 684: 113-125, 2019 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-31153061

RESUMO

In forest ecosystems, litter quality is a major driver for soil and understorey characteristics, but elevation, microtopography and subsoil properties may also be important. We tested the importance of each factor in two ancient mixed forests on decalcified marl, dominated by trees with different litter quality such as European hornbeam, with high-palatable litter, and beech, with low-palatable litter. We mapped elevation, differences in local height (microtopography), tree distribution and understorey cover on slopes ranging from crest to bottom, and sampled 200 7 × 7 m grid cells for characteristics of litter input, understorey, topsoil and subsoil. In both forests, elevation decreased gradually, but microtopography showed irregular patterns of depressions and mounds of a few cm below or above average local height. Tree distribution was not affected by elevation or subsoil properties, but clearly by microtopography. Adult beech was abundant on local mounds, while hornbeam was more common in local depressions. Topsoil and understorey characteristics were mainly affected by litter quality (tree species dominance) and microtopography. Litter quality had separate effects from microtopography, but could reinforce this. High litter quality (hornbeam) and low local height both led to high earthworm activity, low litter mass, high erosion, impermeable clay layers close to the surface, high pH, high soil moisture and high diversity of the understorey. Low litter quality (beech) and high local height both led to low earthworm activity, high litter mass, low erosion, low pH, low soil moisture and low plant diversity. Beech and hornbeam may act as ecosystem engineers, which change habitat conditions and local hydrology, and make habitats more suitable to themselves, and/or unsuitable to the other. However, they also increased spatial complexity of the forest and length of the habitat gradient. This may increase forest biodiversity as a whole, but also resilience to prolonged wet or dry periods.


Assuntos
Biodiversidade , Florestas , Dispersão Vegetal , Solo/química , Árvores/fisiologia , Geografia , Luxemburgo
18.
Am J Bot ; 106(6): 760-771, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31157413

RESUMO

PREMISE: Cambial activity in some tropical trees varies intra-annually, with the formation of xylem rings. Identification of the climatic factors that regulate cambial activity is important for understanding the growth of such species. We analyzed the relationship between climatic factors and cambial activity in four tropical hardwoods, Acacia mangium, Tectona grandis, Eucalyptus urophylla, and Neolamarckia cadamba in Yogyakarta, Java Island, Indonesia, which has a rainy season (November-June) and a dry season (July-October). METHODS: Small blocks containing phloem, cambium, and xylem were collected from main stems in January 2014, October 2015 and October 2016, and examined with light microscopy for cambial cell division, fusiform cambial cells, and expanding xylem cells as evidence of cambial activity. RESULTS: During the rainy season, when precipitation was high, cambium was active. By contrast, during the dry season in 2015, when there was no precipitation, cambium was dormant. However, in October 2016, during the so-called dry season, cambium was active, cell division was conspicuous, and a new xylem ring formation was initiated. The difference in cambial activity appeared to be related to an unusual pattern of precipitation during the typically dry months, from July to October, in 2016. CONCLUSIONS: Our results indicate that low or absent precipitation for 3 to 4 months induces cessation of cambial activity and temporal periodicity of wood formation in the four species studied. By contrast, in the event of continuing precipitation, cambial activity in the same trees may continue throughout the year. The frequency pattern of precipitation appears to be an important determinant of wood formation in tropical trees.


Assuntos
Câmbio/anatomia & histologia , Câmbio/fisiologia , Chuva , Árvores/anatomia & histologia , Árvores/fisiologia , Acacia/anatomia & histologia , Acacia/crescimento & desenvolvimento , Acacia/fisiologia , Câmbio/crescimento & desenvolvimento , Divisão Celular , Eucalyptus/anatomia & histologia , Eucalyptus/crescimento & desenvolvimento , Eucalyptus/fisiologia , Agricultura Florestal , Indonésia , Lamiaceae/anatomia & histologia , Lamiaceae/crescimento & desenvolvimento , Lamiaceae/fisiologia , Rubiaceae/anatomia & histologia , Rubiaceae/crescimento & desenvolvimento , Rubiaceae/fisiologia , Estações do Ano , Especificidade da Espécie , Árvores/crescimento & desenvolvimento
19.
Ying Yong Sheng Tai Xue Bao ; 30(5): 1608-1614, 2019 May.
Artigo em Chinês | MEDLINE | ID: mdl-31107017

RESUMO

Non-structural carbohydrates (NSC, including soluble sugars and starch) are key meta-bolites in tree, the storage characteristics of which in tree organs have received extensive attention. It is still unclear how NSC are allocated in the tissues (phloem and xylem) that have different function. In this study, we analyzed the concentration and allocation of NSC in the roots, and in phloem and xylem of the trunk in three dominant species of broadleaved Korean pine forest in the Changbai Mountain, Pinus koraiensis, Fraxinus mandschurica, and Tilia amurensis. The results showed that there was a significant difference in the concentration of NSC between the phloem and xylem. The soluble sugar dominated in the phloem, while starch dominated in the xylem. The concentration of NSC in trunk outside (divided by annual rings, 0-20 years), intermediate (20-40 years) and inner (>40 years) of different tree species was significantly different, but with no difference in the roots. The total soluble sugar concentration in the phloem of P. koraiensis and F. mandschurica was significantly higher than that of T. amurensis, while the difference in xylem was not significant. The results indicated that NSC allocation in the phloem and xylem of the tree had clear tissue differentiation, which might be related to the succession stage of the tree species or the functional evolution of the tissue. These findings would improve our understanding of the carbon storage characteristics and allocation mechanism in temperate trees.


Assuntos
Carboidratos/fisiologia , Monitoramento Ambiental , Florestas , Árvores/fisiologia , China , Pinus
20.
Tree Physiol ; 39(6): 971-982, 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-31086983

RESUMO

Evergreen tree species that maintain positive carbon balance during the late growing season may subsidize extra carbon in a mixed forest. To test this concept of 'carbon subsidy', leaf gas exchange characteristics and related leaf traits were measured for three gymnosperm evergreen species (Chamaecyparis thyoides, Tsuga canadensis and Pinus strobus) native to the oak-hickory deciduous forest in northeast USA from March (early Spring) to October (late Autumn) in a single year. All three species were photosynthetically active in Autumn. During the Summer-Autumn transition, photosynthetic capacity (Amax) of T. canadensis and P. strobus increased (T-test, P < 0.001) and was maintained in C. thyoides (T-test, P = 0.49), while dark respiration at 20 °C (Rn) and its thermal sensitivity were generally unchanged for all species (one-way ANOVA, P > 0.05). In Autumn, reductions in mitochondrial respiration rate in the daylight (RL) and the ratio of RL to Rn (RL/Rn) were observed in P. strobus (46.3% and 44.0% compared to Summer, respectively). Collectively, these physiological adjustments resulted in higher ratios of photosynthesis to respiration (A/Rnand A/RL) in Autumn for all species. Across season, photosynthetic biochemistry and respiratory variables were not correlated with prevailing growth temperature. Physiological adjustments allowed all three gymnosperm species to maintain positive carbon balance into late Autumn, suggesting that gymnosperm evergreens may benefit from Autumn warming trends relative to deciduous trees that have already lost their leaves.


Assuntos
Ciclo do Carbono , Chamaecyparis/fisiologia , Pinus/fisiologia , Árvores/fisiologia , Tsuga/fisiologia , New York , Folhas de Planta/fisiologia , Transpiração Vegetal , Estações do Ano
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