This study investigates the effect of the spatial distribution of soil water and nutrients on cork oak (Quercus suber) architecture. Fertirrigation is being tested in cork oak plantations to accelerate tree growth up to the production stage. To assess the impact of wet bulb location on tree development, six trees (three subjected to subsurface drip irrigation and three controls) were fully excavated at a sandy soil site, along with a seventh tree subjected to surface drip irrigation at a sandy loam soil site. The aerial parts of the trees were digitized using a Polhemus Fastrak magnetic digitizer and segmented into orders starting from the main trunk. Roots with diameters greater than 0.5 cm were digitized during excavation and segmented by size and order from the root collar. For each segment, length, orientation, and spatial location were calculated. General linear models were then applied to compare total root length across orientation and quadrant classes. Crown architecture was influenced by factors such as light competition. Irrigation treatments did not significantly affect root architecture when wet bulb formation was constrained. However, tree no. 7 had 50% of its total root length located within the wet bulb quadrant. These findings suggest that differences in soil type and irrigation method influence wet bulb formation, potentially reducing the impact of fertirrigation on root architecture. Strategies to minimize tree dependence on wet bulb zones are crucial for enabling future irrigation suppression.

In the context of climate change conditions, addressing the shifting composition of forest stands and changes in traditional forest management practices are necessary. For this purpose, understanding the biomass allocation directly influenced by crown architecture is crucial. In this paper, we want to demonstrate the possibility of 3D mensuration of canopy architecture with the digitizer sensor Fastrak Polhemus and demonstrate its capability for assessing important structural information for forest purposes. Scots pine trees were chosen for this purpose, as it is the most widespread tree species in Europe, which, paradoxically, is very negatively affected by climate change. In our study, we examined young trees since the architecture of young trees influences their growth potential. In order to get the most accurate measurement of tree architecture, we evaluated the use of the Fastrak Polhemus magnetic digitizer to create a 3D model of individual trees and perform a subsequent statistical analysis of the data obtained. It was found that the stand density affects the number of branches in different orders and the heights of the trees in the process of natural regeneration. Regarding the branches, in our case, the highest number of branch orders was found in the clear-cut areas (density = 0.0), whereas the lowest branching was on-site with mature stands (density = 0.8). The results showed that the intensity of branching (assessed as the number of third-order branches) depends on the total number of branches of the tree of different branch orders but also on stand density where the tree is growing. An important finding in this study was the negative correlation between the tree branching and the tree height. The growth in height is lower when the branching expansion is higher. Similar data could be obtained with Lidar sensors. However, the occlusion due to the complexity of the tree crown would impede the information from being complete when using the magnetic digitizer. These results provide vital information for the creation of structural-functional models, which can be used to predict and estimate future tree growth and carbon fixation.

Cork oak ( Quercus suber L.) mortality events have spurred scientific research into new afforestation techniques, particularly the use of fertigation to accelerate tree growth and hasten the onset of the productive phase when cork stripping becomes feasible. This study examines the effects of fertigation on the development of root and aerial systems, with the objective of determining if fertigation can eventually be discontinued without compromising tree vitality. Six seven-year-old trees growing under natural conditions were selected for analysis, grouped into three pairs, each with similar crown sizes but subjected to different watering regimes – fertigation and rainfed. These trees were analyzed using the Fastrak Polhemus method, focusing on seven parameters: volume, area, length, root diameter, root-to-shoot ratio, shape area, and circularity. Analyses were conducted both graphically and using partial correlation statistics. The findings indicate that tree size accounted for the most significant differences in these parameters. Conversely, fertigation was associated with an increase in trunk volume, while rainfed conditions led to larger root diameters, likely as an adaptation to drought. The most pronounced differences were observed in smaller trees, where both groups exhibited unbalanced but opposing root-to-shoot ratios: rainfed trees invested more in root development, while fertigation trees prioritized aerial growth. The impact of irrigation on the development of below-ground and above-ground biomass in arid regions is crucial in the context of ongoing climate change, which will further intensify drought during the growing seasons.

Accurate measurement of tree architecture is vital for understanding forest dynamics and supporting effective forest management. This study evaluates close-range photogrammetry (CRP) using TreeQSM (v2.4.1) software, reconstructing 3D tree structures in both deciduous and coniferous species and comparing its performance to the Fastrak 3D digitizing method. CRP proved less labor-intensive and effective for estimating parameters like tree height, stem diameter, and volume of thicker branches in small trees. However, it struggled with capturing intricate structures, overestimating volumetric values and underestimating branch lengths and counts. Mean relative root mean square errors for height, diameter at 0.3 m height, volume, and branch count were 34.19%, 69.9%, 107.87%, and 142.03%, respectively. These discrepancies stem from challenges in reconstructing moving objects and filtering non-woody elements. While CRP shows potential as a complementary method, further advancements are necessary to improve 3D tree model reconstruction, emphasizing the need for ongoing research in this domain.