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40 results for “tree age”
Tree ages and Locations on the Eastern Shore of Virginia National Wildlife Refuge
Cores were taken from live trees in the hillslope site in the Eastern Shore of Virginia National Wildlife Refuge. "TreeAges.csv" has the ID of the tree, the UTM 18N Easting and Northing and the NAVD88 Elevation (these are identical to the hillslope "ALIVE" points in the topographic surveys - dataset VCR19288), and the year that the tree was established from the dendrochronology analysis. Complete methods for the dendrochronology analysis can be found in Fernandes et al. (2018) Declining radial growth response of coastal forests to hurricanes and nor'easters. JGR: Biogeosciences. (https://doi.org/10.1002/2017JG004125) Location and elevation data were collected using a real-time kinematic (RTK) Global Positioning System (GPS) unit.
Is tree age or tree size reducing height increment in Abies alba Mill. at its southernmost distribution limit?
<p>Many factors limit height increment of trees when age and size increase in large-statured tree species. Height-diameter allometric relationships are commonly used measures of tree growth.</p> <p>The data were collected in a silver fir forest located in Southern Italy, at the southernmost distribution limit for this species. Through a stratified random sampling, 100 trees were selected. All the selected trees were then felled and the total tree height, height increments (internode distances), diameter at breast height, and diameter increments (ring widths) were measured.</p> <p>Conventional methods for estimating the current annual increment of stand volume are based on the uncertain assumption that height increment decreases with tree age. Conversely, size, rather than age, should be accounted for the observed senescence-related declines in relative growth rate and, consequently, implemented in silvicultural manuals. Results stem from a study on Abies alba Mill. at its southern limit of distribution.</p>
Twig age data from 12 tree species sampled in S & N Wisconsin and Upper Michigan
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Influence of tree height and age on leaf drip-tip morphology in lowland tropical rain forest trees
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Sex and age differences in tree cavity dependence in a small arboreal marsupial
<p>Many mammal species depend on tree cavities for shelter and for breeding. Some species may use tree cavities as well as other varied shelters but the extent of their dependence on tree cavities is unknown. One such species is the eastern pygmy-possum (<i>Cercartetus nanus</i>) from eastern Australia which typically shelters alone. I addressed four key questions: i) do different age and sex classes differ in their preferences for small (4 cm diameter) and large (10 cm diameter) cavities, ii) does the availability of large cavities influence female breeding status, iii) does the availability of large cavities influence where adult females and males are detected, and iv) does the availability of large cavities influence survival and abundance? I provisioned two 9-ha plots containing few (≤2 per ha) 'large' natural cavities with artificial cavities in different years. When plots were provisioned with small and large cavities breeding females (<i>n</i> = 46) showed a pronounced preference for sheltering in the large cavities whilst adult males (<i>n</i> = 67) and subadults (<i>n </i>= 40) preferred the small cavities. When one plot and not the other was provisioned with large cavities adult females were significantly more likely to be reproductive and be detected on the plot with large cavities, but survival was not influenced. Detection of adult males did not vary with large cavity provisioning. The abundance of adult pygmy-possums varied among years, being higher on the plot provisioned with large cavities when the other plot was not provisioned, but equivalent when both were provisioned. The findings of this study are consistent with the hypothesis that breeding females are dependent on a large cavity to raise a litter. Other mammal species around the world are likely to exhibit similar but currently unrecognised shelter site strategies which have implications for their management.</p>
Data from: Leaf size in three generations of a dioecious tropical tree, Ocotea tenera (Lauraceae): sexual dimorphism and changes with age
PREMISE OF THE STUDY: In dioecious species, selection should favor different leaf sizes in males and females whenever the sexes experience distinct environments or constraints, such as different costs of reproduction. We took advantage of a long-term experimental study of Ocotea tenera (Lauraceae), a dioecious understory tree in Monteverde, Costa Rica, to explore leaf size differences between genders and age classes across generations. METHODS: We measured leaf size in adult trees in a natural population, in their adult F1 offspring in two experimental populations, and in their F2 offspring at the seedling stage. Individual trees were measured at various times over a 20-year period. RESULTS: Leaves of female trees averaged 8% longer and 12% greater in area than those of males. Leaves were sexually dimorphic at reproductive maturity. Leaf size declined over the course of most trees' lifetimes. Heritability estimates for leaf length were positive although not statistically significant (h2 = 0.63, SE = 0.48, P= 0.095). CONCLUSIONS: We ruled out the "ecological causation" hypothesis for sexual dimorphism in leaf size because male and female trees co-occurred in the same habitats. Sexual dimorphism appeared not to result from genetic or phenotypic correlations with other traits such as height or flower size. Rather, females appear to compensate for higher costs of reproduction and diminished photosynthetic capacity by producing larger leaves. Additive genetic variance in leaf size, a prerequisite for an evolutionary response to selection for sexual dimorphism, was suggested by positive (although only marginally significant) heritability estimates.
Figure 6. Maximum credibility Bayesian tree obtained from a in Morphology and Bayesian tip-dating recover deep Cretaceous-age divergences among major chrysidid lineages (Hymenoptera: Chrysididae)
Figure 6. Maximum credibility Bayesian tree obtained from a combined analysis of a partitioned dataset of 300 morphological characters employing a relaxed morphological clock model with tip-dating. Character-state transformations (ChN, character; ChS, character state) are colour-coded with tagma as represented in the diagram on the bottom, and are depicted as solid (unequivocal changes) or empty (reversed or multiple changes) charts; mesosomal characters derived from legs and wings are depicted as rectangle and hexagon portrayals respectively; slow changes (DelTran optimization) are indicated by '+'. Fossil taxa are indicated by daggers. Phylogenetic relationships among Chrysididae (Clade 1) are shown in detail in Figures 7–12.
FIGURE 3. a. Acer campestre young tree bark. b. Aged tree bark. c in Confirmation of Acer campestre (Sapindaceae) presence in Algeria and new sites records
FIGURE 3. a. Acer campestre young tree bark. b. Aged tree bark. c. Shoot of the year. d. Axillary bud. e. Terminal bud. Photographed by S. Ait Said (a–b) and Z. Chikhaoui (c–e).
Data from: Leaf size in three generations of a dioecious tropical tree, Ocotea tenera (Lauraceae): sexual dimorphism and changes with age
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Data from: A novel growth model evaluating age-size effect on long-term trends in tree growth.
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Data from: Exact distribution of divergence times from fossil ages and tree topologies
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Sex and age differences in tree cavity dependence in a small arboreal marsupial
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Data from: Age-dependent and lineage-dependent speciation and extinction in the imbalance of phylogenetic trees
It is known that phylogenetic trees are more imbalanced than expected from a birth–death model with constant rates of speciation and extinction, and also that imbalance can be better fit by allowing the rate of speciation to decrease as the age of the parent species increases. If imbalance is measured in more detail, at nodes within trees as a function of the number of species descended from the nodes, age-dependent models predict levels of imbalance comparable to real trees for small numbers of descendent species, but predicted imbalance approaches an asymptote not found in real trees as the number of descendent species becomes large. Age-dependence must therefore be complemented by another process such as inheritance of different rates along different lineages, which is known to predict insufficient imbalance at nodes with few descendent species, but can predict increasing imbalance with increasing numbers of descendent species.
Data from: Age-dependent and lineage-dependent speciation and extinction in the imbalance of phylogenetic trees
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Data from: Size-related scaling of tree form and function in a mixed-age forest
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ABoVE: Tree Canopy Cover and Stand Age from Landsat, Boreal Forest Biome, 1984-2020
This dataset contains Landsat-derived locally-calibrated estimates of tree canopy cover (TCC) and forest stand age across global boreal forests from 1984-2020 in Cloud-Optimized GeoTIFF (*.tif) format. These raster data span the circum-hemispheric boreal forest biome between 47 to 73 degrees north at 30 m resolution. Machine learning models calibrated with data from the World Reference System 2 were used to predict TCC from Landsat data at 30-m spatial resolution at annual temporal resolution. Through analysis of TCC time series, forest change estimates of stand age from 1984-2020 were developed. The broad spatial and temporal coverage of these data provide insight into forest and carbon dynamics of the global boreal forest system. Boreal forests store a large proportion of global soil and biomass carbon and have experienced disproportionately high levels of warming over the past century.
LBA-ECO CD-08 Radiocarbon Dating of Tree Ages in Amazonas, Acre, and Para in Brazil
This data set reports the ages and growth rates of trees determined by radiocarbon dating (14C) in three Amazonia forests. Tree samples were collected from permanent research plots at ZF2 km 34, Manaus, Amazonas, the Catuaba Experimental Farm, Acre, and the km 83 tower site (logged forest site) in the Tapajos National Forest, Para, between 2001-2003.Samples from 97 individual trees were either tree cores (Manaus and Acre) or a combination of tree cores and slabs cut from stems as part of the logging in the Tapajos National Forest (Para). Radiocarbon dating (14C) was used to determine the age and the mean diameter growth increment of samples from individual trees in various diameter size classes. These measurements can be used to verify and extend short-term diameter increment measurements done with dendrometers and to constrain models of tree demography.There is one comma-separated ASCII data file with this data set.
Single-nucleus transcriptomic sequencing and cross integration comparison of multiple species revealed new cell composition and specific gene marker in hippocampal aging of tree shrew
GEO Series GSE229035. Tupaia belangeri. 15 samples. Type: Expression profiling by high throughput sequencing.
A single-nucleus transcriptomic atlas reveals cellular and genetic characteristics in the hippocampus of natural aging-inducing Alzheimer’s disease tree shrews
GEO Series GSE235838. Tupaia belangeri. 6 samples. Type: Expression profiling by high throughput sequencing.
Single-cell nuclear transcriptome sequencing and cross-species analysis reveal tree shrew retina Age-associated cellular profiles and specific markers
GEO Series GSE227524. Tupaia belangeri. 15 samples. Type: Expression profiling by high throughput sequencing.
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.