Vulnerability assessment of European forests to climate changes by multitemporal and multiscale approach

Dr. Giuseppe D'Andrea, MSc.

Disertační práce

Abstract:

The recent phenomenon of forest dieback has occurred in many forest types (biomes). Among these are the Mediterranean zone and Central European region in the zone of deciduous broadleaved forests which have different climate types. The focus of this thesis was to compare the global climate change (GCC) impact of forest stands/ecosystems using the specific approach: the evaluation of Normalized Difference Vegetation Index (NDVI) and dendrochronological reactions of selected stands on temperature and precipitation dynamics. For this purpose, we focused on the most important coniferous and deciduous tree species, i.e., Norway spruce and European beech. For the research, we selected: six Norway spruce plots in the Czech Republic, one European beech plot in Poland, two beech plots in the Czech Republic, and three beech plots in Italy, reflecting the areal range of this species. The spruce plots were chosen in three regions of the central part of the Czech Republic: Karlštejn (1–2), Cukrák (3–4), and Kostelec (5–6) (Figure 12) with an altitude ranging between 319 and 422 m a.s.l. (Table 2), representing the hilly flat area. For beech, three sites in Central Europe (Chojnik 1, Rýchory 2, Rýchory 27 (Figure 22)) with an altitude between 510 and 1030 m a.s.l. (Table 3) and three sites in Southern Europe (Sellata 3, La Lama 4, Monte Volturino 5 (Figure 22)) were selected having an altitude between 1275 and 1740 m a.s.l. (Table 3). We used an open-source tool, Climate Engine, to obtain NDVI MODIS (MOD13Q1 collection 6 product) time-series collections from 2000 to 2018 in the spruce study and from 2000 to 2017 in the beech study to discuss the possible imbalance in NDVI patterns between several sites. For dendrochronological analysis, the core samples from 180 spruce and 180 beech individuals were provided by Pressler borer, i.e., 30 samples per research plot. Tree-ring samples were collected at breast height (1.3 m), perpendicular to the slope, following the standard dendrochronological procedures. The cross-dating procedure was performed by Cdendro software (Cybis Electronik & Data), while tree-ring widths were measured by LINTAB (Rinntech) with an Olympus binocular magnifier, from bark to the pith (on a scale of 0.01 mm) and sets of tree-ring data were processed with TSAP-Win software. From this study, it was revealed that the Norway spruce despite the low altitudes, if grows on soils with a good water availability (as in the case of the KO 1 locality), reports good growth rate (Table 4); while European beech had substantial values of radial growth in sites located at lower altitudes compared to the sites located at higher altitudes. Therefore, radial growth decreases with increasing altitude at both Central European and Southern European study sites (Table 5). Despite the dryer study plots in southern Italy than the plots in the Czech Republic and Poland, they showed a higher radial growth than the rest of the study sites. This result shows us that despite the GCC, beech forests at low altitudes have shown higher values of radial growth. Future studies are needed to verify if the affected plots have an optimal microclimate for beech radial growth or if there are other factors that we have not taken into consideration that could have positively influenced the radial growth of the trees. In the studied lowland forests, it was observed that precipitation during the growing season had a positive effect on spruce radial growth, while temperature during the growing season had a negative effect on radial growth (Table 6). In the case of beech located at different vegetative belts observed in selected sites, the same results (for the major part of the study plots) were found (but the correlations in this case were not significant) (Table 7). As for the relationship between remote data (NDVI) and field data (RWI) of Norway spruce, the maximum NDVI values of the growing season tended to be more correlated than the mean NDVI values fo

Abstract:

r most sites. The higher correlations were found in sites susceptible to drought, but despite of the general view, the correlation was not significant (Table 6). In the case of beech, the most significant positive correlations to radial growth were observed with maximum seasonal NDVI in Southern European plots located at lower altitudes (Table 7). In general, the study confirmed that the relationship between NDVI and RWI is more correlated in drier locations, such as the Mediterranean ones, and further studies are needed to state whether NDVI is also a valid indicator for less arid locations like those of Central Europe, and to state whether it is a reliable index for both deciduous and coniferous trees.

Keywords

Global climate change (GCC), NDVI (Normalized Difference Vegetation Index), air temperature, precipitation, forest health, Norway spruce, European beech, dendrochronology

Jazyk práce: angličtina

Datum vytvoření / odevzdání či podání práce: 22. 1. 2024

Obhajoba závěrečné práce

• Vedoucí: prof. Ing. Vilém Podrázský, CSc.

Česká zemědělská univerzita v Praze

Fakulta lesnická a dřevařská

Doktorský studijní program / obor:
Forestry Engineering / Silviculture