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61.
Vertical (arboreality) and horizontal (dispersal) movement increase the resilience of vertebrates to climatic instability
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62.
森林年龄结构一直是森林生态学研究的重要内容之一,利用胸径指标间接推测树木年龄是获得森林年龄结构的有效手段。基于黑龙江省小兴安岭林区156株成熟红松解析木数据,分析成熟红松个体胸径与年龄之间关系,探讨地形与竞争因子对红松胸径与年龄关系的影响。研究结果表明:对所搜集的红松解析木数据,海拔、坡度、坡向、竞争因子等因素都对红松胸径与年龄关系产生影响,其中坡向与坡位对红松胸径-年龄关系影响最为明显,而竞争因子的影响较小并且在不同地形条件下表现出差异性。在南坡向-中坡位的红松个体,其胸径与年龄之间表现出了最佳的拟合效果。对地形与竞争因子的影响机理还有待于进一步研究。 相似文献
63.
A non-destructive method of total vertical projections for estimating the length of rigid root systems, not introduced yet
in plant sciences, is described. It is demonstrated on measuring less and more dense root systems of seedlings of Zea mays
grown at hypoxic or control conditions. Photographs of six vertical projections (30° apart) of each root system were taken
and evaluated. The method being based on proved mathematical formula offers unbiased estimation of the length of a rigid root
system, curved in three-dimensional space, by non-destructive means. Thus, it is applicable during ongoing experimentation
on plants grown in a solution culture. It was shown that less than 120 intersections between the root projection and test
lines in one photograph ensured sufficient precision of the method and that the observer subjectivity could be overcome by
presented instructions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
64.
CO2 evasion from boreal lakes: Revised estimate,drivers of spatial variability,and future projections
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Adam Hastie Ronny Lauerwald Gesa Weyhenmeyer Sebastian Sobek Charles Verpoorter Pierre Regnier 《Global Change Biology》2018,24(2):711-728
Lakes (including reservoirs) are an important component of the global carbon (C) cycle, as acknowledged by the fifth assessment report of the IPCC. In the context of lakes, the boreal region is disproportionately important contributing to 27% of the worldwide lake area, despite representing just 14% of global land surface area. In this study, we used a statistical approach to derive a prediction equation for the partial pressure of CO2 (pCO2) in lakes as a function of lake area, terrestrial net primary productivity (NPP), and precipitation (r2 = .56), and to create the first high‐resolution, circumboreal map (0.5°) of lake pCO2. The map of pCO2 was combined with lake area from the recently published GLOWABO database and three different estimates of the gas transfer velocity k to produce a resulting map of CO2 evasion (FCO2). For the boreal region, we estimate an average, lake area weighted, pCO2 of 966 (678–1,325) μatm and a total FCO2 of 189 (74–347) Tg C year?1, and evaluate the corresponding uncertainties based on Monte Carlo simulation. Our estimate of FCO2 is approximately twofold greater than previous estimates, as a result of methodological and data source differences. We use our results along with published estimates of the other C fluxes through inland waters to derive a C budget for the boreal region, and find that FCO2 from lakes is the most significant flux of the land‐ocean aquatic continuum, and of a similar magnitude as emissions from forest fires. Using the model and applying it to spatially resolved projections of terrestrial NPP and precipitation while keeping everything else constant, we predict a 107% increase in boreal lake FCO2 under emission scenario RCP8.5 by 2100. Our projections are largely driven by increases in terrestrial NPP over the same period, showing the very close connection between the terrestrial and aquatic C cycle. 相似文献
65.
Yuri Miura Noritaka Hashii Yuki Ohta Yoko Itakura Hiroki Tsumoto Junya Suzuki Daisuke Takakura Yukiko Abe Yasumichi Arai Masashi Toyoda Nana Kawasaki Nobuyoshi Hirose Tamao Endo 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(6):1462-1471
Background
Glycosylation is highly susceptible to changes of the physiological conditions, and accordingly, is a potential biomarker associated with several diseases and/or longevity. Semi-supercentenarians (SSCs; older than 105?years) are thought to be a model of human longevity. Thus, we performed glycoproteomics using plasma samples of SSCs, and identified proteins and conjugated N-glycans that are characteristic of extreme human longevity.Methods
Plasma proteins from Japanese semi-supercentenarians (SSCs, 106–109?years), aged controls (70–88?years), and young controls (20–38?years) were analysed by using lectin microarrays and liquid chromatography/mass spectrometry (LC/MS). Peak area ratios of glycopeptides to corresponding normalising peptides were subjected to orthogonal projections to latent structures discriminant analysis (OPLS-DA). Furthermore, plasma levels of clinical biomarkers were measured.Results
We found two lectins such as Phaseolus vulgaris, and Erythrina cristagalli (ECA), of which protein binding were characteristically increased in SSCs. Peak area ratios of ECA-enriched glycopeptides were successfully discriminated between SSCs and controls using OPLS-DA, and indicated that tri-antennary and sialylated N-glycans of haptoglobin at Asn207 and Asn211 sites were characterized in SSCs. Sialylated glycans of haptoglobin are a potential biomarker of several diseases, such as hepatocellular carcinoma, liver cirrhosis, and IgA-nephritis. However, the SSCs analysed here did not suffer from these diseases.Conclusions
Tri-antennary and sialylated N-glycans on haptoglobin at the Asn207 and Asn211 sites were abundant in SSCs and characteristic of extreme human longevity.General significance
We found abundant glycans in SSCs, which may be associated with human longevity. 相似文献66.
Sensilla lining the inner walls of the sacculus on the third antennal segment of Drosophila melanogaster were studied by light and transmission electron microscopy. The sacculus consists of three chambers: I, II and III. Inside each chamber morphologically distinct groups of sensilla having inflexible sockets were observed. Chamber I contains no-pore sensilla basiconica (np-SB). The lumen of all np-SB are innervated by two neurons, both resembling hygroreceptors. However, a few np-SB contain one additional neuron, presumed to be thermoreceptive. Chamber II houses no-pore sensilla coeloconica (np-SC). All np-SC are innervated by three neurons. The outer dendritic segments of two of these neurons fit tightly to the wall of the lumen and resemble hygroreceptor neurons. A third, more electron-dense sensory neuron, terminates at the base of the sensillum and resembles a thermoreceptor cell. Chamber III of the sacculus is divided into ventral and dorsal compartments, each housing morphologically distinct grooved sensilla (GS). The ventral compartment contains thick GS1, and the dorsal compartment has slender sensilla GS2. Ultrastructurally, both GS1 and GS2 are doublewalled sensilla with a longitudinal slit-channel system and are innervated by two neurons. The dendritic outer segment of one ofthe two neurons innervates the lumen of the GS and branches. On morphological criteria, we infer this neuron to be olfactory. The other sensory neuron is probably thermoreceptive. Thus, the sacculus in Drosophila has sensilla that are predominantly involved in hygroreception, thermoreception, and olfaction. We have traced the sensory projections of the neurons innervating the sacculus sensilla of chamber III using cobaltous lysine or ethanolic cobalt (II) chloride. The fibres project to the antennal lobes, and at least four glomeruli (VM3, DA3 and DL2-3) are projection areas of sensory neurons from these sensilla. glomerulus DL2 is a common target for the afferent fibres of the surface sensilla coeloconica and GS, whereas the VM3, DA3 and DL3 glomeruli receive sensory fibres only from the GS. 相似文献
67.
Foliar phosphorus (P) and nitrogen (N) concentrations and nutrient resorption in the forest understory shrub Lonicera maackii (Rupr.) Maxim (Caprifoliaceae) were measured along contiguous topographic gradients in two southwestern Ohio forests during 1992–1994. Mean summer foliar P varied significantly among topographic positions (but not sites or years), with uplands having greatest P concentrations and bottomlands exhibiting the lowest. Unlike for P, the mean summer foliar N concentrations varied little among sites, topographic positions, and years. Mean absolute and proportional P resorption ranged from 0.48 mg/dm2 (33.7%) in slope positions to 0.80 mg/dm2 (53.1%) in bottomland positions. Repeated-measures analysis of variance (RMANOVA) for P resorption indicated significant topographic and year effects, a site × year and a site × year × topographic interaction. Mean absolute and proportional foliar N resorption ranged from 6.82 mg/dm2 (30.7%) in bottomlands to 8.41 mg/dm2 (37.3%) in slope positions. RMANOVA indicated a significant topographic effect for both absolute and proportional N resorption and a significant year effect for absolute N resorption. These significant year effects for P and N stemmed from lowest resorption of nutrients in 1993. The results for P resorption support the hypothesis that foliar resorption is greater in forested sites with lower P fertility. However, resorption rates for N did not support the hypothesis clearly, as slopes with intermediate N availability had greater N resorption rates than did N-rich bottomlands. 相似文献
68.
Gregg D. Jacobs Herbert Benson Richard Friedman 《Applied psychophysiology and biofeedback》1996,21(2):121-129
The purpose of this study was to assess the central nervous system effects of the relaxation response (RR) in novice subjects using a controlled, within-subjects design and topographic EEG mapping as the dependent measure. Twenty subjects listened to a RR and control audiotape presented in a counterbalanced order while EEG was recorded from 14 scalp locations. TheRR condition produced greater (p<.0164) reductions in frontal EEG beta activity relative to the control condition. No significant differences were observed for any other frequency band or scalp region. These findings suggest that elicitation of the RR produces significant reductions in cortical activation in anterior brain regions in novice subjects. 相似文献
69.
Stimulation of cerebellar interpositus nucleus and (astigial nucleus could influence the neuronal activi-ty of lateral hypothalamic area in the cat, and some of the neurons which respond to the cerebellar stimulations are glucose-sensitive neurons. These results suggest that the cerebellum is involved not only in motor control, but also in the regulation of non-somatic functions through the cerebello-hypothalamic pathways. 相似文献
70.
Soil properties and above-and belowground forest structure were studied across various topographies in a 20-year-oldPinus thunbergii Parl. plantation on Mt Tanakami, Japan. The soil properties and stand structure varied greatly with slope position fromridge
top to valley floor. Soil thickness, fine soil content and soil moisture content were greater in lower slope positions. The
amount of organic carbon in the forest floor was greater in upper slope positions. The organic carbon content in the mineral
soil was slightly greater in lower slope positions. These changes in soil properties suggested an upslope decrease in decomposition
rate and water and/or nutrient availability. The aboveground structure ofP. thunbergii was more developed at lower slope positions. The mean stem diameter, height and volume ofP. thunbergii increased downslope with decreasing tree density. However, fine root biomass increased greatly upslope. This inverse relationship
between tree height and fine root biomass indicated morphological plasticity ofP. thunbergii in exploiting environmental heterogeneity. Variations in soil-plant interactions in the stand along various topographies
caused spatial heterogeneity in the accumulation pattern of organic matter in plants and the soil. 相似文献