Search Results (3)

Trunk sap flow is essential for assessing plant water use efficiency and adaptation, yet the mechanisms underlying drought resistance and water utilization strategies in dry and hot valleys remain poorly understood. This study investigates the sap flow dynamics of four tree species (Albizia kalkora, Diospyros dumetorum, Terminalia franchetii, and Acacia auriculiformis) in a dry and hot valley using Granier’s thermal diffusion probe method. The aims were to analyze interspecific differences and their response mechanisms to environmental factors using a fitted model of sap flow density and transpiration variables, supplemented by Pearson’s and Mantel’s tests. The results showed that (1) the trunk sap flow of each tree species is significantly higher in the wet season than in the dry season. (2) In the dry and wet seasons, the average trunk sap flow rates were in the order Albizia kalkora > Diospyros dumetorum > Terminalia franchetii > Acacia auriculiformis. (3) The correlation between environmental factors and trunk sap flow was in the order photosynthetically active radiation > atmospheric temperature > saturated water vapor pressure difference > relative humidity > wind speed. (4) Deciduous plants demonstrated stronger water-conducting capacities than evergreen plants and native plants exhibited better drought resistance than introduced plants. (5) Acacia auriculiformis and Albizia kalkora were identified as rainfall-sensitive plants, while Diospyros dumetorum and Terminalia franchetii were rainfall-insensitive. By optimizing species selection based on water use efficiency, rainfall sensitivity, and environmental conditions such as light and temperature, this research contributes to enhancing the stability and resilience of ecosystem restoration in arid regions. Full article

Surface fuel removal is crucial to facilitate the mitigation of severe fires in forests. Prescribed burning is often used by forest managers, thanks to its low cost and high efficiency in hard-to-reach areas. The determination of heat transfer between fires and trees has rarely been carried out on living species and consequently, their long-term effects on tree physiology are still not fully understood. In this study, a multidisciplinary approach was conducted to evaluate the impact of a late spring (June) prescribed burning on a Mediterranean pine forest (Pinus nigra subsp. laricio). The surface fuels consisted of a 656 g m⁻² needle litter, mixed with a few scattered living herbaceous strata. During the fire spread, measurements of the inner and outer trunk temperatures were made at the base of 12 trees with an average bark thickness of 19.4 ± 7.0 mm. The fireline intensity and flame residence time were in the range of 110–160 kW m⁻¹ and 220–468 s, respectively. Despite a maximum heating rate at the cambial area of 4.37 °C min⁻¹, the temperature of these tissues remained below 60 °C, a critical threshold above which thermal damage will occur. In addition, prior- and post-fire physiological monitoring was performed over a long time period (2.5 years) on 24 trees, using sap flow, chlorophyll fluorescence and gas exchange measurements. All parameters remain highly correlated and indicate that the burned trees did not suffer physiological damage. Moreover, drought resistance strategies were not altered by the prescribed burning. The thermal insulation capability of the bark allowed the functional tissues to experience low heat stress that did not affect tree vitality. Full article

The paper presents an original method for the evaluation of bark structure characteristics of tree trunks on the basis of terrestrial laser scanning data. Measurements testing the method proposed were performed in laboratory conditions for trunks of pine (Pinus sylvestris L.) and oak (Quercus robur L.). The laser scanner used was a FARO Focus 3D. The scanning was carried out in two variants for natural trunks (variant I: samples Oak-I, Pine-I) and for trunks wrapped in foil (variant II: samples Oak-II, Pine-II). The point clouds obtained were combined into a three-dimensional (3D) model, filtered, and exported to the *.xyz format in SCENE (v. 5×) software provided by FARO. For calculation of the bark structure characteristics the geoprocessing Tree Trunk Bark Structure Model (TTBSM) operating in the ArcGIS environment was developed. The mean bark height factor (BHF) of the natural pine and oak tree trunks was calculated to be 0.39 cm and 0.37 cm, while the values for the trunks wrapped in foil were 0.27 cm and 0.25 cm, respectively. The BHF of the tree trunks wrapped in foil varied in the range 0.26–0.28 cm and 0.24–0.26 cm for pine and oak, respectively, while for the natural tree trunks the range was 0.38–0.46 cm and 0.35–0.38 cm for pine and oak, respectively. The effect of BHF on the flow resistance was evaluated in a measuring trough and proved to be significant. The coefficient of flow resistance was on average 20% higher for the natural tree trunks than for those foil-wrapped. Full article