Michael Bartoš

Integration in the clonal plant Eriophorum angustifolium : an experiment with a three-member-clonal system in a patchy environment

A clonal plant in heterogeneous environments is usually expected to profit from resource exchange via a clonal network where ramets placed in contrasting environments can specialise so to acquire the most abundant resources. An experiment was designed using the three member clonal system of Eriophorum angustifolium, which consisted of one parent ramet growing in a resource poor environment and two offspring: one was limited in growth by nutrients while the other was light limited; the contrast in availability of limited resources between the offspring ramets was high, medium or none, with the system either connected or severed. The total resource availability was the same in all treatments. We proposed four possible scenarios for the system: offspring ramets will share resources via the deficient parent ramet, and the whole clone will profit from the contrasting environment (scenario 1); offspring ramets will support exclusively the parent ramet, and the whole clone will profit from a homogeneous environment (scenario 2); offspring ramets will stop the export of the limiting resource to the parent ramet, with split and connected treatments not differing (scenario 3); and offspring ramets will exhaust the carbon stored in the biomass of the parental ramet; offspring ramet will profit from connection (scenario 4). In the experiment, the limiting resources were sent to the strongest sink (scenario 2). The parent ramet growing in a deficient environment received the highest support in the treatment where both offspring ramets were growing in the same conditions (no-contrast treatment). Production of new shoots, but not biomass of whole clone, was supported in a homogenous environment. The experiment revealed that multiple stresses might prohibit free exchange of limiting resources via the clonal network and supports the idea that experimental studies on more complex clones are essential for understanding the costs and benefits of clonal growth.

Plant Diversity Changes during the Postglacial in East Asia: Insights from Forest Refugia on Halla Volcano, Jeju Island

Understanding how past climate changes affected biodiversity is a key issue in contemporary ecology and conservation biology. These diversity changes are, however, difficult to reconstruct from paleoecological sources alone, because macrofossil and pollen records do not provide complete information about species assemblages. Ecologists therefore use information from modern analogues of past communities in order to get a better understanding of past diversity changes. Here we compare plant diversity, species traits and environment between late-glacial Abies, early-Holocene Quercus, and mid-Holocene warm-temperate Carpinus forest refugia on Jeju Island, Korea in order to provide insights into postglacial changes associated with their replacement. Based on detailed study of relict communities, we propose that the late-glacial open-canopy conifer forests in southern part of Korean Peninsula were rich in vascular plants, in particular of heliophilous herbs, whose dramatic decline was caused by the early Holocene invasion of dwarf bamboo into the understory of Quercus forests, followed by mid-Holocene expansion of strongly shading trees such as maple and hornbeam. This diversity loss was partly compensated in the Carpinus forests by an increase in shade-tolerant evergreen trees, shrubs and lianas. However, the pool of these species is much smaller than that of light-demanding herbs, and hence the total species richness is lower, both locally and in the whole area of the Carpinus and Quercus forests. The strongly shading tree species dominating in the hornbeam forests have higher leaf tissue N and P concentrations and smaller leaf dry matter content, which enhances litter decomposition and nutrient cycling and in turn favored the selection of highly competitive species in the shrub layer. This further reduced available light and caused almost complete disappearance of understory herbs, including dwarf bamboo.

Problems of agriculture and landscape management as perceived by farmers of the Šumava Mountains (Czech Republic)

Abstract The role agriculture plays in our economy is changing. The former preference for production is being replaced by a preference for the production of landscape. The landscape we live in has been created by rural tradition. It is the kind of landscape we perceive as pleasant; it is also highly appreciated from the ecological and aesthetic points of view. The problem facing us is how we should preserve the character of the rural landscape, which is closely connected with agricultural activity, under conditions of decreasing agricultural production. This question is extremely important in marginal areas whose economy is based on agriculture. Declining agricultural production in these areas results not only in social changes but also in changes in the landscape patterns of environmentally valuable areas. One possible solution to this problem is a policy of landscape management. This has been tried out in the Czech Republic, by implementing new types of subsidies in agricultural policy, to encourage sustainable landscape management. Our article seeks to reveal the shortcomings in the functioning of these ecological subsidies in marginal areas. Our qualitative analysis is based on interviews with farmers in Sumava Mountains to ascertain their opinions and experience with ecological subsidies as a new form of state support. The main reason that the ecological subsidies are failing appears to be because they ignore the social factor: the recipient of the subsidy. Most of the subsidies are awarded to businessmen (‘new experts’) who have no ties with the landscape or with its values and management. We conclude that the landscape cannot be managed from outside. We need a living countryside with farmers — recipients of subsidies and the real creators of the landscape. The social situation in the countryside must be taken into account in a broader context.

Generalization versus Specialization in Pollination Systems: Visitors, Thieves, and Pollinators of Hypoestes aristata (Acanthaceae)

Many recent studies have suggested that the majority of animal-pollinated plants have a higher diversity of pollinators than that expected according to their pollination syndrome. This broad generalization, often based on pollination web data, has been challenged by the fact that some floral visitors recorded in pollination webs are ineffective pollinators. To contribute to this debate, and to obtain a contrast between visitors and pollinators, we studied insect and bird visitors to virgin flowers of Hypoestes aristata in the Bamenda Highlands, Cameroon. We observed the flowers and their visitors for 2-h periods and measured the seed production as a metric of reproductive success. We determined the effects of individual visitors using 2 statistical models, single-visit data that were gathered for more frequent visitor species, and frequency data. This approach enabled us to determine the positive as well as neutral or negative impact of visitors on H. aristata’s reproductive success. We found that (i) this plant is not generalized but rather specialized; although we recorded 15 morphotaxa of visitors, only 3 large bee species seemed to be important pollinators; (ii) the carpenter bee Xylocopa cf. inconstans was both the most frequent and the most effective pollinator; (iii) the honey bee Apis mellifera acted as a nectar thief with apparent negative effects on the plant reproduction; and (iv) the close relationship between H. aristata and carpenter bees was in agreement with the large-bee pollination syndrome of this plant. Our results highlight the need for studies detecting the roles of individual visitors. We showed that such an approach is necessary to evaluate the pollination syndrome hypothesis and create relevant evolutionary and ecological hypotheses.

Amenity Migration in the Context of Landscape-Ecology Research

Amenity Migration in the Context of Landscape-Ecology Research Amenity migration is a specific type of migration that is not economically motivated. Rather it is brought about by a desire to render more valuable the natural or socio-cultural environment of the target territory, and it is often directed from metropolitan to rural areas. This phenomenon has been strongly supported by the spread and growing accessibility of mass information technologies. As with any other kind of migration, it can lead to changes in the spatial distribution of human activities in the target territory. Under specific conditions, it can become one of the driving societal forces determining the socio-economic development of a given rural region. In the European context, amenity migration appears to be in its early stages of development. As such, it has been the subject of theoretical debate rather than being documented by empirical evidence. Amenity migration can be seen as an ambiguous phenomenon. Optimistic hypotheses claim that it could support local development of rural space and thus diminish the disproportionate development of particular regions and that it can maintain or even improve these regions environmental and cultural quality. On the other hand, it can also lead to a massive invasion of urban behavioural patterns into rural areas, making them culturally uniform. Tried and tested GIS methods exist for identifying a landscapes potential for amenity migration. The use of qualitative and quantitative techniques is a useful and progressive approach to landscape ecological research. We can expect further progress in the methods used to study amenity migration and for evaluating rural development within a landscape context following further research on amenity migrants, which will take place over the coming years.

Specialization of pollination systems of two co-flowering phenotypically generalized Hypericum species (Hypericaceae) in Cameroon

The degree of specialization in plant–pollinator relationships is probably the most intensively discussed topic of pollination biology. Phenotypically generalized flowers are typically also considered to be generalized ecologically and/or functionally. Our study focuses on visitors to flowers of Hypericum roeperianum and H. revolutum, two closely related co-flowering Afromontane plants with flat flowers, which can be visited by many insects. We collected insect visitors and recorded their behaviour. Both Hypericum species were visited by large numbers of morphospecies and functional groups, which might indicate that they are highly generalized plants. Nevertheless, after including the visitors’ abundance, behaviour and contact with the plants’ reproductive organs, only a single carpenter bee species could be considered an effective pollinator of H. roeperianum, and a few smaller bee species (mainly Apis mellifera and Meliplebeia ogouensis) could be considered as effective pollinators of H. revolutum. Despite the fact that the flowers appear at first glance phenotypically generalized, both species seem to be ecologically and functionally specialized for bee pollination. Our results indicate that even phenotypically generalized flowers can be functionally and ecologically specialized. More precise knowledge of their visitors’ behaviour is crucial for understanding their pollination systems. Our results cast doubts upon the currently leading opinion that generalization prevails in pollination systems, as such conclusions are based mainly on community-wide studies, which usually do not consider the true role of insect visitors.

Effects of disturbance regime on carbohydrate reserves in meadow plants

Plants in unmown meadows are able to store large amounts of carbohydrates. These stores, however, become depleted during winter and/or spring and thus do not differ from levels in mown plots at the peak of the next growing season. It is clear, moreover, that although carbohydrate concentrations at first reflect the carbohydrate mobilization needed for resprouting in response to plant damage and then the refilling of reserves thereby expended, the total carbohydrate amounts are affected by the growth of storage organs. Although concentrations and total amounts of carbohydrates reflect different aspects of plant carbohydrate storage, their concentration might sufficiently describe short-term effects of disturbance.

Changes in Migration to Rural Regions in The Czech Republic: Position and Perspectives

Abstract Migration trends in the Czech Republic after 1990 are discussed in this paper. To evaluate the migration trends, the databases of immigrants and emigrants from the Czech Statistical Office from 1990 to 2010, are used. While migration from rural areas to urban areas prevailed in the past, after 1990 the direction changed: the population in rural areas with good natural and socio-cultural environments has been increasing due to migration. Small municipalities have a positive migration balance. We can conclude that these trends could be influenced primarily by social and environmental problems in cities, the increase in automobile use and the development of communication technologies, the migration of pensioners who settle in second homes, and the changing residential preferences of people and entrepreneurs. Shrnutí Článek hodnotí migrační trendy ve venkovských oblastech v České republice po roce 1990. K hodnocení byla použita databáze přistěhovalých a vystěhovalých Českého statistického úřadu za období 1990-2010. Zatímco v minulosti převažovala migrace z venkovských oblastí do měst, po roce 1990 se směr migrace změnil: počet obyvatel ve venkovských oblastech s dobrým přírodním a příznivým socio-kulturním prostředím roste díky migraci. Malé obce mají kladné migrační saldo. Lze předpokládat, že tyto trendy by mohly být ovlivněny především sociálními a ekologickými problémy ve městech, zvýšením motorizace a rozšířením komunikačních technologií, stěhováním důchodců do objektů druhého bydlení a změnami preferencí bydlení.

Interference Competition Between Sunbirds and Carpenter Bees for the Nectar of Hypoestes aristata

Interference competition for nectar sources has been repeatedly described between hummingbirds and various insects, but rarely recorded in other nectarivorous birds. We observed aggressive behaviour by African sunbirds (Cinnyris reichenowi and Cinnyris bouvieri) defending the nectar plant Hypoestes aristata against carpenter bees (Xylocopa caffra and Xylocopa inconstans) in the Bamenda Highlands, Cameroon. During 200 hours of observation, we recorded 38 cases of the sunbirds attacking carpenter bees; all these intrusions occurred only in the flower-richest patches of the plant.We predict that similar aggressive interactions will occur between other Old World nectarivorous birds and insects. Such interference competition between distantly related taxa could have an important impact on the evolution of pollination systems.

The potential benefit of intracarpal pressure measurement in endoscopic carpal tunnel syndrome surgery--an analysis of EMG findings and pressure values.

Endoscopic carpal tunnel syndrome surgery is a modern minimally invasive method of carpal tunnel decompression. However, the method does also have its critics, who emphasize that there is an increased rate of complications in comparison to open procedures. To further improve and optimize results of endoscopic surgery we used an intracarpal pressure sensor to verify the effect of carpal tunnel decompression. The endoscopic single portal approach was used in all cases. Median nerve conduction studies were performed prior to and 3 months after surgery. Two groups, those with pressure studies and those without, were then compared according to several EMG parameters such as: median nerve distal motor latency, amplitude of motor response, sensory nerve conduction velocity to the index finger, and amplitude of sensory nerve action potential. In both groups, we observed similarly significant improvements in all conduction parameters, except the amplitude of motor response, which did not change in either group, i.e. no difference in postoperative EMG between the two groups was observed. Despite this fact, intracarpal pressure measurement is still useful in localising the point in which the median nerve is compressed and provides valuable functional information on the level decompression achieved.