Search results for "diameter [Area]"
showing 6 items of 16 documents
Modelling dendro-anthracological parameters with dendrochronological reference datasets: interrogating the applicability of anthraco-typology to asse…
2020
International audience; Aleppo pine (Pinus halepensis Miller) is present in the palaeoenvironmental records of Mallorca (Balearic Islands, Western Mediterranean) since the Early Holocene. It is also documented in the archaeological charcoal analysis (aka anthracology) of early prehistoric sites, but it was especially exploited at certain sites during the Late Iron Age. However, different woodland exploitation strategies cannot be deciphered purely through the taxonomical identification of charcoal fragments, so it is difficult to assess if the presence of Aleppo pine in archaeological assemblages is due to specific social management strategies (branches and/or trunks exploitation). Anthraco…
Dynamics of natural hemiboreal woodland in the Moricsala Reserve, Latvia: the studies of K. R. Kupffer revisited
2010
Abstract Karl Reinhold Kupffer (1872–1935), an outstanding botanist and plant ecologist, took the initiative that led to the establishment of the first nature reserve in Latvia, on Moricsala Island in 1912. The reserve provided an excellent reference area for natural hemiboreal woodland for future generations. There have been very few studies on the dynamics of natural broadleaved forest in Europe, probably owing to lack of primeval forests of this type. However, Kupffer produced a map of forest types in the reserve with accurate descriptions of the vegetation by layers, and his descriptions include interpretations of forest dynamics processes. This information, together with the present ag…
Influence of ocular aberrations on the diameter of retinal blood vessels
2011
Lower-order and higher-order ocular aberrations influence not only visual perception but also appearance of retinal images. We suggest that the diameter of blood vessels may differ for various patterns of aberrations based on how the maps of point spread functions are orientated to these vessels. We tested our hypothesis by a star chart simulation method and by using simulating aberrations in a real image of a living retina. We observed that broadening of the blood vessels due to ocular aberrations depends not only on the relative orientation of the wavefront but also on their actual width. The change in the diameter ratio is clinically significant and is comparable to changes in the arteri…
Bayesian Mapping of Lichens Growing on Trees
2001
Suitability of trees as hosts for epiphytic lichens are studied in a forest stand of size 25 ha. Suitability is measured as occupation probabilites which are modelled using hierarchical Bayesian approach. These probabilities are useful for an ecologist. They give smoothed spatial distribution map of suitability for each of the species and can be used in detecting high- and low-probability areas. In addition, suitability is explained by tree-level covariates. Spatial dependence, which is due to unobserved spatially structured covariates, is modelled through an unobserved Markov random field. Markov chain Monte Carlo method has been applied in Bayesian computation. The extensive spatial data …
Recent applications of point process methods in forestry statistics
2000
Forestry statistics is an important field of applied statistics with a long tradition. Many forestry problems can be solved by means of point processes or marked point processes. There, the "points" are tree locations and the "marks" are tree characteristics such as diameter at breast height or degree of damage by environmental factors. Point pro- cess characteristics are valuable tools for exploratory data analysis in forestry, for describing the variability of forest stands and for under- standing and quantifying ecological relationships. Models of point pro- cesses are also an important basis of modern single-tree modeling, that gives simulation tools for the investigation of forest stru…
Relaciones suelo-vegetación en una toposecuencia del Escudo Guayanés, Venezuela
2014
El Escudo Guayanés es uno de los territorios más antiguos del planeta; tiene millones de años sometido a procesos de lixiviación y erosión que dejan suelos oligotróficos. El objetivo de este trabajo fue hacer la caracterización de los parámetros físicos y químicos de los suelos, en diferentes comunidades boscosas de la Reserva Forestal Imataca, e identificar ciertas relaciones entre los componentes edáficos y las especies que allí se presentan. Se realizó un inventario de todos los individuos mayores a 10cm dap (diámetro a la altura del pecho) en 15 parcelas (1ha); en cada una de esas parcelas se evaluaron cuatro sub-parcelas de sotobosque (100m²) para contabilizar todas las espermatofitas;…