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Tytuł:
Subspace memory clustering
Autorzy:
Struski, Łukasz
Spurek, Przemysław
Tabor, Jacek
Opis:
We present a new subspace clustering method called SuMC (Subspace Memory Clustering), which allows to efficiently divide a dataset D c RN into k 2 N pairwise disjoint clusters of possibly different dimensions. Since our approach is based on the memory compression, we do not need to explicitly specify dimensions of groups: in fact we only need to specify the mean number of scalars which is used to describe a data-point. In the case of one cluster our method reduces to a classical Karhunen-Loeve (PCA) transform. We test our method on some typical data from UCI repository and on data coming from real-life experiments.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Effects of different fire severity levels on soil chemical and physical properties in Zagros forests of western Iran
Autorzy:
Ali, Mahdavi
Mehdi, Heydari
Ali, Salehi
Mostafa, Adibnejad
Wydawca:
Instytut Badawczy Leśnictwa, Komitet Nauk Leśnych PAN
Opis:
Przemysław Szmit
The study focused on the effect of different intensities of fire on physical and chemical properties of soil in Zagros forests of western Iran. The dominant tree species in these forests is oak (Quercus persica). Three sites were selected; high severity burned site (HS), low severity burned site (LS) and control (not burned) site (C). Soil chemical properties such as: organic matter (OM), the total nitrogen (N), NO3-N, soluble potassium (K), soil phosphorus (P), pH, soil electrical conductivity (EC), cation exchangeable capacity (CEC), base cations (Ca, Mg, Na), CO2 and soil physical properties such as saturation percentage (SP), bulk density (BD), sand, clay and silt percentages were assessed in soil samples. To determine significance of differences among the three observed sites and most effective variables in the separation of sample plots, one-way analysis of variance and principal component analysis were used, respectively. Mean pH, N, NO3- N, OM, SP, P, K, and CEC at HS site were lower than at the sites with other fire intensities but the EC value for HS site was higher in comparison with other sites observed. According to Duncan's test, mean BD value for HS site was higher when compared with other sites but SP value was comparatively lowest. At LS site, mean sand content was lowest and the amount of silt was highest, in comparison with other sites. The results showed that observed fire severities had significant effects on physical and chemical properties of soil, yet fire low severity and control sites were very similar to each other in terms of investigated factors. Therefore, it can be concluded that low-severity fire regime has no significant influence on soil properties. In a management strategy, controlled low-severity fire regime can be an alternative management tool in improving soil conditions.
Dostawca treści:
Repozytorium Centrum Otwartej Nauki
Artykuł
Tytuł:
The impact of drought in 2015 on the health forest condition determined using Landsat-8 OLI images
Autorzy:
Rynkiewicz, Alicja
Rotchimmel, Karol
Kacprzak, Mariusz
Nasiłowska, Sylwia A.
Kotlarz, Jan
Kubiak, Katarzyna
Wydawca:
Instytut Badawczy Leśnictwa (Forest Research Institute), Sękocin Stary, Poland
Cytata wydawnicza:
Nasiłowska, S. A., Kotlarz, J., Kacprzak, M., Rynkiewicz, A., Rotchimmel, K., & Kubiak, K. (2019). The impact of drought in 2015 on the health forest condition determined using Landsat-8 OLI images, Forest Research Papers, 80(1), 55-68. doi: https://doi.org/10.2478/frp-2019-0005
Opis:
The main aim of this research was to determine the impact of drought (in 2015) on forests stand condition using remote sensing and statistical techniques. The study was based on the analysis of vegetation indices calculated from a series of Landsat-8 OLI satellite images covering the 2014 and 2015 growing seasons. Various tree biophysical and physical parameters as well as forest habitat characteristics were tested in order to find the most significant factors affecting drought resistance. Three approaches were used: (i) index differences, (ii) PCA analysis, and (iii) ANOVA statistical analysis. All three approaches used in this study indicate that forest biodiversity is the most important factor determining habitat response to stress conditions. Coniferous and mixed tree habitats were less sensitive than deciduous ones. Statistical analysis revealed the relationship between stress and soil types, as those more permeable were less dependent on rainwater. The highest stress was found for precipitation-dependent gley soils. Undergrowth density and height were also indicated as important factors inducing habitat response to a changing weather situation. All the results confirmed the usefulness of mid-infrared based indices for water shortage monitoring in forests. They confirmed that habitat biodiversity has a positive effect on its resistance to stressful conditions. Also forest type (conifer/deciduous) determines it's sensitivity. Precipitation and groundwater shortages have different effects on the forest condition depending on soil type.
Dostawca treści:
Repozytorium Centrum Otwartej Nauki
Artykuł
Wyświetlanie 1-10 z 23

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