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

Provenance affects the growth and mortality of teak (Tectona grandis L.f.) plantations cultivated in central Nicaragua

Teak has been planted extensively by smallholders in Central America within reforestation programmes and has become one of the most valuable timbers. The five-year growth and mortality of teak cultivated in a plantation in central Nicaragua, representing sites at the low limit of teak ecological valence, were evaluated. From 2006 to 2010, 72 pure teak stands were established, with 48.93 ha in total. For afforestation, planting stock from five provenances was used and planted at 1 m x 1 m spacing to stimulate the height growth and reduce broad crowns formed by self-pruning. In the pure teak stands, 144 permanent sample plots of 0.01 ha in size were established in 2011. From 2011 until 2015, the tree height and stem girth of all individuals in the studied sample plots were measured, and mortality based on the stand density was assessed. Significant differences between the provenances were observed. The highest growth was noted in the Local provenance originated from the studied area, whereas the Semilla provenance from Costa Rica, characterised by the lowest growth ability, was characterized by lower radial increment and mean tree height with high mortality.O

Predicted occurrence of ancient coppice woodlands in the Czech Republic

Coppicing started in the Neolithic period and has been practiced throughout European history. This traditional silvicultural system was abandoned in many European countries during the 20th century. The Czech Republic now has a very low proportion of coppice woods (CW), as more than 1000 km2 CW were converted into high forests after World War II. Nevertheless, many CW were maintained as stored coppices, which could be the last remainders of ancient coppice woods (ACW) in the Czech Republic. Knowledge of area and distribution of stored coppices is currently missing in the Czech Republic, because they are recorded as high forests in forest management plans. Many stored forests are currently approaching the maturity age, with a high risk that these last ACW remainders will be lost; therefore, an inventory of ancient coppice woods is necessary. In our study, we develop an index of likelihood of coppice occurrence (COP) based on the distribution of habitats favourable for coppices, as well as on past and current occurrence of CW in the Czech Republic from historical maps. COP index values were then used to generate a map showing the relative likelihoods of occurrence of ACW, which can serve as a baseline to support the compilation of an ACW inventory and their mapping in the field. Our results can help prioritize forest areas to be inventoried based on their higher probabilities of ACW occurrence.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

Seed Viability and Potential Germination Rate of Nine Endemic Boswellia Taxa (Burseraceae) from Socotra Island (Yemen)

The endemic Boswellia species (Burseraceae) on Socotra Island (Yemen) are of great local significance due to their various local ethnobotanical uses. However, despite the fact that these trees are endangered, little is known about their biology. We tested seed germination rates in controlled experiments (trials of 21 days) for two subsequent years and for nine endemic taxa of Boswellia occurring on Socotra Island. For this, seeds were collected island-wide from a wide range of localities and for several populations per species. We observed differences in germination among Boswellia species, among species and localities and among both years, which indicates that the development of seeds is strongly affected by external ecological factors. Although we noted a large variation in seed germination (relatively high in Boswellia socotrana), and half of the species showed relatively low mean daily germination, our study indicated that all endangered endemic Frankincense Tree taxa of Socotra harbor the potential for in situ conservation through recruitment, given that known impacts can be reduced in local replantation areas (e.g., grazing).O

Starobylé výmladkové lesy v krajině České republiky

Ancient coppice woodlands are forest stands of coppice origin with a long-term continual development and preserved typical natural and historic elements of old coppices. Significant natural elements in ancient coppices include polycormons of coppice shoots, pollard trees, trees with holes, dendrotelms, reserved trees, ecotones, glades and significant plant and animal species. Significant historic elements of localities with ancient coppices include archaeological monuments, boundary ditches and walls, boundary stones, boundary trees, myths and legends, sacral objects, old roads and paths, technical objects and plough land remainders. The paper presents differentiation of assumptions for the occurrence of ancient coppices in the territory of the Czech Republic using the COPF coefficient and examples of results from basic regional inventory (Kuřim region) and detailed local survey (locality Lebeďák) of coppice-originated forests. The extinction of the phenomenon of ancient coppice woodlands would mean irreparable impoverishment of the natural and cultural heritage.Za starobylé výmladkové lesy označujeme lesní porosty výmladkového původu s dlouhodobým kontinuálním vývojem a zachovanými typickými přírodními a historickými prvky starých pařezin. K významným přírodním prvkům ve starobylých pařezinách patří výmladkové polykormony, hlavaté stromy, doupné stromy, dendrotelmy, výstavky, ekotony, světliny a významné druhy rostlin a živočichů. Mezi významné historické prvky lokalit starobylých výmladkových lesů řadíme archeologické památky, hraniční příkopy a valy, hraniční kameny, hraniční stromy, pověsti a legendy, sakrální objekty, staré cesty a stezky, technické objekty a zbytky plužiny. V článku je prezentována diferenciace předpokladů výskytu starobylých pařezin na území České republiky s využitím koeficientu COPF a příklady výsledků základního regionálního (Kuřimsko) a podrobného lokálního (Lebeďák) průzkumu lokalit lesů výmladkového původu. Zánik fenoménu starobylých pařezin by znamenal nenapravitelné ochuzení přírodního a kulturního dědictví.O

Climate change effects on the potential distribution of the endemic Commiphora species (Burseraceae) on the island of Socotra

The Socotra Archipelago (Yemen) is an interesting biodiversity hotspot, with a significant proportion of endemic species that have evolved to survive in an arid subtropical environment, inscribed as a World Heritage Site by UNESCO. The terrestrial ecosystems of Socotra face several threats, including climate change, overgrazing and soil degradation. Socotra Island has four endemic species of the genus Commiphora (Burseraceae). Little is known about their local distribution and ecology, yet these trees could be useful indicator species. Our study focuses on the distribution and niche characterisation of the four endemic Commiphora species of Socotra and how climate change may affect them. The aim is to improve insights into their habitats and to provide an essential basis for future local management plans and ecological restoration. We compared the current distribution with the forecasted potential distribution under a CMIP6 (Coupled Model Intercomparison Project) climate scenario, allowing us to define target conservation areas and assess potential local extinction risks. To achieve this, we collected distribution data in the field throughout Socotra Island, covering the current distribution ranges of the four species. To assess the potential distribution of these species, we applied three models (GAM, MaxEnt, RandomForest) using bioclimatic, topographic and soil variables. Forecasts under a climate change scenario were made using bioclimatic variables from the CMCC-CESM2 climate model for two different socioeconomic pathways. The distribution of three endemic Socotran Commiphora is mainly correlated to clay content in the soil and winter precipitation, while C. socotrana is affected by seasonal precipitation and temperature. Under different potential future climate scenarios, the distribution of C. ornifolia is predicted to remain stable or increase, while C. parvifolia distribution could increase, yet C. planifrons and C. socotrana are predicted to undergo a strong reduction of suitable areas and an upward shift in the mountains. Our results highlight that it is essential to conserve the unique terrestrial ecosystems in Socotra and to preserve these endemic trees which have a wide range of ecosystem services. Updates on the predicted extinction risk assessment are fundamental to understand conservation priorities and strategize future actions to ensure the persistence of Socotran myrrh trees and other endangered endemic tree taxa on the island

supplementary material for submission to Sustainability

supplementary material for submission to Sustainabilit