Age Estimation of Dracaena cinnabari Balf. f. on Socotra Island: A Direct Method to Determine Its Lifespan

Background: Dracaena cinnabari is a monocot species that does not form annual tree rings; thus, its age can only be estimated. This species is threatened by low natural regeneration, with an evident absence of younger individuals most likely caused by overgrazing; therefore, knowing trees' ages is important for possible conservation strategies; Methods: Data collection was conducted on the Firmihin Plateau on Socotra Island (Yemen) in 2021, and the diameter at breast height (DBH) of 1077 individuals was measured, the same as those established on monitoring plots 10 years before the current measurement. The 10-year radial stem increment and DBH obtained in 2011 served as a basis for the linear model from which the equations for the age calculation were derived. Results and Conclusions: A direct model of age estimation for D. cinnabari was developed. According to the fit model, the age in the first (10.1-15 cm) DBH class was estimated to be 111 years, while that in the last DBH class (90.1-95 cm) was estimated to be 672 years. The results revealed that the previously used indirect methods for D. cinnabari age estimation were accurate.O

Metrics of Growth Habit Derived from the 3D Tree Point Cloud Used for Species Determination-A New Approach in Botanical Taxonomy Tested on Dragon Tree Group Example

Detailed, three-dimensional modeling of trees is a new approach in botanical taxonomy. Representations of individual trees are a prerequisite for accurate assessments of tree growth and morphological metronomy. This study tests the abilities of 3D modeling of trees to determine the various metrics of growth habit and compare morphological differences. The study included four species of the genus Dracaena: D. draco, D. cinnabari, D. ombet, and D. serrulata. Forty-nine 3D tree point clouds were created, and their morphological metrics were derived and compared. Our results indicate the possible application of 3D tree point clouds to dendrological taxonomy. Basic metrics of growth habit and coefficients derived from the 3D point clouds developed in the present study enable the statistical evaluation of differences among dragon tree species.O

Populace smrku ztepilého při horní hranici lesa v Hrubém Jeseníku

This dissertation presents research results of Norway spruce (Picea abies L. Karst) populations in timberline ecotone of the Hrubý Jeseník Mts. The work is presented in the form of five scientific articles, 3 of which are accepted for publication, or already printed. Two articles are in the form of submitted manuscripts. The first article describes the biometric and age structure of spruce populations, including the assessment of the possibility of their vegetative as well as seed-based reproduction and compares these characteristics between two vertically connected sections of timberline ecotone. The second article analyzes the influence of dwarf pine stands of different cover on the ability of vegetative reproduction of spruce and their height growth. The third article deals with the historical dynamic of spruce trees establishment within timberline ecotone. This are correlated with both temperature characteristics and agricultural land abandonment during the last 100 years. The fourth article deals with measurements of the quantity and directions of sap flow in layering branches as well as parent and daughter trees in Norway spruce clonal groups. The article evaluates the importance of sap flow quantity in layering branch to the total amount of water use by parent and daughter trees. The fifth article substantially extends the fourth article of measurements on more interconnected tree pairs within a longer time series. Additionally, this article includes the drought stress experiment in the daughter tree and subsequent monitoring of changes in sap flow in layering branch

Species-Specific Effects of Groundwater Level Alteration on Climate Sensitivity of Floodplain Trees

European floodplain forest is facing increasingly frequent and severe drought events related with ongoing climate change. Moreover, this ecosystem type was frequently affected by river regulation, leading to groundwater table lowering; however, river revitalization has, in some locations, achieved some restoration of groundwater levels. In this study, we investigated the growth–climate sensitivity and growth modulation after groundwater-level manipulation for Fraxinus angustifolia Vahl. and Quercus robur L. in one of the most important floodplain forest complexes in Central Europe. We constructed three different types of tree ring chronologies to reflect the high frequency variability, medium-low frequency variability, and basal area increment. We found F. angustifolia to be more sensitive than Q. robur to both drought and groundwater level fluctuations. Moreover, F. angustifolia showed more pronounced short-term and long-term growth decreases after artificial ground water level alteration than did Q. robur. We also found that the groundwater level increase due to river revitalization reduced the climate sensitivity for both F. angustifolia and Q. robur. The decrease in climate sensitivity associated with revitalization was more pronounced for F. angustifolia which, moreover, showed a greater basal growth after river revitalization. Our results suggest that F. angustifolia will be more threatened than Q. robur by the diminution in groundwater availability and increase in drought with ongoing climate change. They also show that river revitalization can be a suitable management tool to help the adaptation to climate change

First Age-Estimation Model for Dracaena ombet and Dracaena draco subsp. caboverdeana

Research Highlights: The first model for crown age estimation was developed for Dracaena ombet Heuglin ex Kotschy and Peyr. and D. draco subsp. caboverdeana Marrero Rodr. and R. Almeida. Background and Objectives: Dracaena species are monocotyledon trees without annual tree rings. Most arborescent dragon tree species are endangered; thus, it is important to determine the age structures of these populations for proper conservation management strategies, and for modelling of population trends. For these reasons, it is necessary to develop a methodology of crown age estimation. Materials and Methods: Field data were collected in the Desa’a Forest (Ethiopia) and in Santo Antão (Cape Verde Islands). Trees within each age class, as expressed by the number of branch orders, were measured. The diameter at breast height, tree height, stem height, number of branch orders, number of all leaf rosettes and number of flowering leaf rosettes within the crown were recorded for each sampled tree. The flowering probabilities were counted as input data for the model used. Results: The duration of the interval between flowering events was 5.23 years for D. ombet and 4.94 years for D. draco subsp. caboverdeana. The crown of the oldest tree of D. ombet with 18 branch orders was estimated to be 94.2 years old, and the crown of the oldest tree of D. draco subsp. caboverdeana with 22 branch orders was estimated to be 108.6 years old

Metrics of Growth Habit Derived from the 3D Tree Point Cloud Used for Species Determination—A New Approach in Botanical Taxonomy Tested on Dragon Tree Group Example

Detailed, three-dimensional modeling of trees is a new approach in botanical taxonomy. Representations of individual trees are a prerequisite for accurate assessments of tree growth and morphological metronomy. This study tests the abilities of 3D modeling of trees to determine the various metrics of growth habit and compare morphological differences. The study included four species of the genus Dracaena: D. draco, D. cinnabari, D. ombet, and D. serrulata. Forty-nine 3D tree point clouds were created, and their morphological metrics were derived and compared. Our results indicate the possible application of 3D tree point clouds to dendrological taxonomy. Basic metrics of growth habit and coefficients derived from the 3D point clouds developed in the present study enable the statistical evaluation of differences among dragon tree species

Vliv výsadeb borovice kleče (Pinus mugo) na biotopovou a druhovou diverzitu arkto-alpinské tundry ve východních Sudetech (CHKO Jeseníky‚ NPR Kralický Sněžník)

Výsledky řešení projektu za celé období řešení. Hlavním cílem projektu bylo přinést co nejvíce informací o tom, jakým způsobem interaguje borovice kleč s přírodním prostředím nejvyšších poloh Hrubého Jeseníku a Králického Sněžníku. Prokázané vlivy odůvodňují potřebu asanace porostů borovice kleče v Hrubém Jeseníku. Nástin priorit byl podán v návrhu managementových opatření