Habitat quality is one main trigger for the persistence of butterflies. The effects of the influencing biotic and abiotic factors may be enhanced by the challenging conditions in high-alpine environments. To better our knowledge in this field, we performed a mark-release-recapture study with Boloria pales in the Southern Carpathians. We analysed population structure, movement and foraging behaviour to investigate special adaptations to the alpine environment and to reveal differences between sexes. We compared these aspects in one sector with and one sector without grazing to address the effects of grazing intensity on habitat quality. We observed “soft” protandry, in which only a small number of males appeared before females, and an extended emergence of individuals over the observed flight period, dividing the population’s age structure into three phases; both observations are considered adaptations to high mountain environments. Although both sexes were mostly sedentary, movement differences between them were obvious. Males flew larger distances than females and were more flight-active. This might explain the dimorphism in foraging behaviour: males preferred nectar sources of Asteraceae, females Caprifoliaceae. Transition from the grazed to the ungrazed sector was only observed for males and not for females, but the population density was higher and the flight distances of the individuals were significantly longer on the grazed sector compared with the ungrazed one. Soft protandry, an extended emergence of the individuals and an adapted behavioural dimorphism between sexes render to represent a good adaptation of B. pales to the harsh environmental conditions of high mountain ecosystems. However, land-use intensity apparently has severe influence on population densities and movement behaviour. To protect B. pales and other high-alpine species from the negative consequences of overgrazing, areas without or just light grazing are needed.
The Alcon Blue Maculinea alcon and the Mountain Alcon Blue Maculinea ‘ rebeli ’ are obligate ant‐parasitic butterflies with no distinct morphological and genetic differences but clear ecological separation. The two butterflies generally lay their eggs on distinct host plant species: M. alcon on Gentiana pneumonanthe and M . ‘ rebeli ’ on Gentiana cruciata . The egg‐laying behaviour of these two ecotypes has previously only been investigated in sympatric, but not in syntopic populations. We studied the egg‐laying preferences of M. alcon and M . ‘ rebeli ’ in a unique area where they co‐occur, and where they use different host plants. The distance to the nearest other host plant does not seem to influence the decision of female butterflies as to whether to lay eggs on a specific host plant. The two butterflies laid their eggs on different parts of their host plants: M. alcon preferred the sepals of G. pneumonanthe flower buds, while M . ‘ rebeli ’ laid most eggs on the leaves of G. cruciata . The major factor correlated with the number of eggs laid on the host plant seemed to be plant quality (number of flowers, stem length, etc.) for both butterflies. The present study reveals behavioural differences between the two Alcon Blue forms under unique syntopic conditions, a hidden intraspecific diversity that is worth conserving.
The article reports the growth stop phenomenon, which was documented only for baobabs, i.e. for trees belonging to the Adansonia genus. The identification of growth stop was enabled by radiocarbon dating, which allows a complex investigation of samples collected from the trunk/stems of baobabs. In several cases, the outermost rings of baobabs, which were close to the bark, were found to be old, with ages of several hundreds of years, instead of being very young. Dating results of samples collected from six baobabs are presented. For multistemmed baobabs, the growth stop may occur only for one or several stems. We identified four factors that may induce the growth stop: (i) stress determined by severe climate conditions, (ii) old age, (iii) the need to keep a stable internal architecture, and (iv) the collapse of stems that survive this trauma. Baobabs and their stems affected by growth stop may survive for several centuries, by continuing to produce leaves, flowers, and fruits. This phenomenon was associated with the capacity of baobabs to store large amounts of water in their trunks/stems in the rainy season. This reservoir of water is used during the dry season and allows the trees to survive prolonged drought periods.
The year 2016 witnessed the fall of a symbol of the botanical world: the historic Chapman baobab of Botswana. This article presents the results of our investigation of the standing and fallen tree. The Chapman baobab had an open ring-shaped structure composed of six partially fused stems. Several wood samples collected from the stems prior and after their collapse were analysed by using radiocarbon dating. The radiocarbon date of the oldest sample was 1381 ± 22 BP, which corresponds to a calibrated age of 1345 (+10, −15) calendar years. The dating results show that the six stems of the Chapman baobab belonged to three different generations, which were 1350–1400, 800–1000 and 500–600 years old. The growth rate variation of the largest and oldest stem is presented and correlated with the climate evolution in the area over the past 1000 years. The factors that determined the sudden fall and death of the Chapman baobab are also presented and discussed.
The Omusati region belongs to historic Ovamboland, an area of northern Namibia populated by tribes of the Ovambo group. Four very large African baobabs of Omusati played an important role in historic events of the area, such as the tribal wars and the Namibian War of Independence. The four historic baobabs are the Ombalantu baobab (8 stems; circumference 24.50 m), Okahao baobab (4+ stems; around 25 m), Amadhila baobab (12 stems; 25.35 m) and Sir Howard baobab (9 stems; 31.60 m). Two historic baobabs collapsed totally or partially. The stems of the Amadhila baobab toppled and died in 2021, while 3 stems of the Okahao baobab collapsed a long time ago, but are still alive. Our research aimed to determine the architecture and age of these baobabs. Three baobabs (Ombalantu, Amadhila, Sir Howard) exhibit a closed ring-shaped structure, with a false cavity inside. One baobab (Okahao) had an open ring-shaped structure, before its collapse. Several wood cores were extracted from the baobabs and investigated by radiocarbon dating. The dating results indicate ages of 770 ± 50 years for the Ombalantu baobab, 650 ± 50 years for the Okahao baobab, 1100 ± 50 years for the Amadhila baobab and 750 ± 50 years for the Sir Howard baobab.