Tag Archives: principal component analysis

215–228 A.A.P.D. Baker, F.C. Da Silva and A.L. Belém
Multivariate analysis of the factors influencing soil organic carbon stock (0–30 cm) based on land use and its transitions in the Atlantic Forest Biome
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Multivariate analysis of the factors influencing soil organic carbon stock (0–30 cm) based on land use and its transitions in the Atlantic Forest Biome

A.A.P.D. Baker¹*, F.C. Da Silva¹ and A.L. Belém²

¹Fluminense Federal University, Department of Agricultural and Environmental Engineering, Niterói, Rio de Janeiro, BR24210-240, Brazil
²Fluminense Federal University, Graduate Program in Ocean and Earth Dynamics, Niterói, Rio de Janeiro, BR24210-240, Brazil
*Correspondence: annaamandipdb@gmail.com

Abstract:

Soil organic carbon (SOC) stocks co‑vary with land use, land‑cover dynamics and their temporal transitions in human‑modified biomes such as the Atlantic Forest. This study explores how land‑use classes and their annual transitions help to understand the dynamics of SOC variability in the 0–30 cm layer using MapBiomas Soil data and Principal Component Analysis (PCA). This study analyzed total SOC stocks, the areal extent of major land uses (forest, pasture, agriculture, non‑vegetated areas, forestry plantations, hydrography and herbaceous vegetation), and their dominant transitions. Correlation analysis indicated positive associations between SOC and pasture, herbaceous vegetation and native forest, whereas agriculture, forestry plantations and non‑vegetated areas were negatively related to SOC stocks, in line with recent findings for Brazilian landscapes. In the PCA, the first component (PC1) captured most of the variance and was strongly associated with SOC and transitions between open and vegetated areas, representing a gradient linked to the intensity of landscape conversion. PC2 was mainly associated with transitions involving gains in forestry plantations, corresponding to a gradient of plantation expansion or contraction, while PC3 was associated with transitions affecting water bodies and wetlands, indicating a secondary axis of SOC variation. Overall, the results suggest that both current land use and the direction and intensity of land‑cover change are key factors associated with SOC stocks. These patterns are consistent with the importance of conserving vegetation cover and promoting stable, sustainable land management to maintain and enhance soil carbon in agricultural and natural environments across the Atlantic Forest biome.

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1364-1372 L. Buša, M. Bērtiņš, A. Vīksna, L. Legzdiņa and D. Kobzarevs
Evaluation of carbon, nitrogen, and oxygen isotope ratio measurement data for characterization of organically and conventionally cultivated spring barley (Hordeum vulgare L.) grain
Abstract |
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Evaluation of carbon, nitrogen, and oxygen isotope ratio measurement data for characterization of organically and conventionally cultivated spring barley (Hordeum vulgare L.) grain

L. Buša¹*, M. Bērtiņš¹, A. Vīksna¹, L. Legzdiņa² and D. Kobzarevs¹

¹University of Latvia, Faculty of Chemistry, Department of Analytical Chemistry, Jelgavas street 1, LV-1004 Riga, Latvia
²Institute of Agricultural Resources and Economics, Priekuli Research Centre, 2 Zinatnes street, LV-4126 Priekuli, Latvia
*Correspondence: lauma.busa@lu.lv

Abstract:

With the growing interest of public in the quality of their consumed food, organic produce has been steadily gaining an important place in everyday menus of our society. The growing demand has boosted organic farming and we have also seen the price difference between organic products and their conventional counterparts. It is important to the public to have security, that the food labelled ‘organic’ has really been grown according to the good practices of organic farming and that it has not received any chemical pesticides, herbicides, and synthetic fertilizers. Stable isotope ratios of crops from different crop management systems can help to answer these questions, as these values depend on the growing conditions, fertilizers used etc. In this study, 10 barley grain samples from conventional and organic crop management systems have been studied. Carbon, nitrogen and oxygen isotope ratios have been determined and the element content in the samples has been calculated. Student’s t-test has been performed to evaluate whether the differences between various parameters are significant. For potential clustering and discrimination of organic and conventional grains principal component analysis has been carried out. The PCA showed that no significant clustering can be observed, however the Student’s t-test for δ15N values confirmed that barley grown with green-manure fertilizers are significantly (p < 0.01) enriched with the heavier nitrogen isotope. Furthermore, it has been concluded that the total element content of carbon and nitrogen in barley grains does not correlate with the stable isotope ratios and cannot help with discriminating of these samples.

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815-826 M. Musto and M. L. Satriano
Fruit responses to postharvest heat treatment time: characterisation of heat-treated strawberry (Fragaria x ananassa) cv. ‘Candonga’ fruits
Abstract |
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Fruit responses to postharvest heat treatment time: characterisation of heat-treated strawberry (Fragaria x ananassa) cv. ‘Candonga’ fruits

M. Musto¹ and M. L. Satriano²

¹Metapontum Agrobios S.r.l., s.s. 106 Jonica Km 448.2, 75010 Metaponto (MT), Italy;
e-mail: mauro.musto@gmail.com
²Freelance researcher

Abstract:

Strawberries cv. ‘Candonga’ were heat-treated in an air oven (45°C) for 0.2 and 4 h,
and then stored at 0°C for 2 days. One-way ANOVA revealed significant differences in terms of
physical and chemical quality properties due to heat treatment time (P=0.000). In particular, as
treatment time increased, strawberries showed a significant decrease of weight, firmness,
redness (a*), yellowness (b*) and colour saturation (chroma). Additionally, the fruits were
darker (lower L* value) after 2 h of treatment and lighter after 4 h (higher L* value). Among
chemical quality properties, ph and soluble solids content (SSC) increased during treatments,
whereas vitamin C content (TAA) decreased. After 4 h of treatment, total anthocyanins and total
soluble phenolics (TSP) significantly decreased and increased, respectively. Principal
component analysis (PCA) was executed on the correlation matrix of significant variables. Two
principal components were extracted, explaining the 73.38% of the data variance. PC1 (60.15%
variance) was associated with most of the physical and chemical variables, whereas PC2
(13.23% variance) was associated with fruit lightness. PCA was found to be of value in
obtaining a visual representation of fruit samples based on heat treatment time.

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