The unprecedented loss of biological diversity has negative impacts on ecosystems and the associated benefits which they provide to humans. Bromeliads have high diversity throughout the Neotropics, but they have been negatively affected by habitat loss and fragmentation, climate change, invasive species, and commercialization for ornamental purpose. These plants provide direct benefits to the human society, and they also form microecosystems in which accumulated water and nutrients support the communities of aquatic and terrestrial species, thus maintaining local diversity. We performed a systematic review of the contribution of bromeliads to ecosystem services across their native geographical distribution. We showed that bromeliads provide a range of ecosystem services such as maintenance of biodiversity, community structure, nutrient cycling, and the provisioning of food and water. Moreover, bromeliads can regulate the spread of diseases, and water and carbon cycling, and they have the potential to become important sources of chemical and pharmaceutical products. The majority of this research was performed in Brazil, but future research from other Neotropical countries with a high diversity of bromeliads would fill the current knowledge gaps and increase the generality of these findings. This systematic review identified that future research should focus on provisioning, regulating, and cultural services that have been currently overlooked. This would enhance our understanding of how bromeliad diversity contributes to human welfare, and the negative consequences that loss of bromeliad plants can have on communities of other species and the healthy functioning of the entire ecosystems.

Boreal mixedwood forests with varying proportions of coniferous and deciduous species are found throughout the North American continent. Maintenance of a deciduous component within boreal forests is currently favoured, as deciduous species are believed to promote faster nutrient turnover and higher nutrient availability. Results of comparisons of deciduous and coniferous forests are, however, inconsistent in supporting this generalization. We compared indices of soil nitrogen (N) availability in the forest floor and mineral soil of deciduous, mixed, and coniferous stands of boreal mixedwood forest in northwestern Alberta. Deciduous stands had higher N availability, reflected by higher pools of NH 4 -N and inorganic N in the forest floor. Forest floors of deciduous stands also tended to have higher concentrations of microbial N but did not have higher levels of NO 3 -N or higher rates of net nitrification. Mixed stands showed the highest rates of net N mineralization. Soil N availability was more closely related to litter N content than to litter decomposition rate. The variation among the forest types is likely attributable to vegetation, as topography is fairly uniform, stands do not differ in soil texture, and N-availability indices correlated directly with the proportion of deciduous trees. Résumé :Les forêts boréales mélangées, qui contiennent des proportions variables de conifères et de feuillus, sont pré-sentes partout sur le continent nord-américain. On encourage actuellement le maintien d'une composante feuillue dans les forêts boréales croyant que les espèces feuillues favorisent un recyclage plus rapide et une plus grande disponibilité des nutriments. Les résultats de comparaisons entre des forêts résineuses et feuillues sont cependant trop inconsistants pour supporter cette généralisation. Les auteurs ont comparé les indices de disponibilité de l'azote (N) du sol dans la couverture morte et le sol minéral de peuplements feuillus, mélangés et résineux de la forêt boréale mélangée du nordouest de l'Alberta. Les peuplements feuillus avaient une plus grande disponibilité de N reflétée par des pools de N-NH 4 et de N inorganique plus importants dans la couverture morte. La couverture morte des peuplements feuillus avait aussi tendance à avoir de plus fortes concentrations de N microbien mais n'avait pas de niveaux plus élevés de N-NO 3 ou de plus hauts taux de nitrification nette. Les peuplements mélangés avaient les taux de minéralisation nette de N les plus élevés. La disponibilité de N du sol était plus étroitement reliée au contenu en N de la litière qu'à son taux de dé-composition. Les différences entre les types de forêts sont probablement attribuables à la végétation étant donné que la topographie est assez uniforme, que les peuplements ont des sols dont la texture est semblable et que les indices de disponibilité de N sont directement corrélés avec la proportion de tiges feuillues.[Traduit par la Rédaction] Jerabkova et al. 122

Abstract:The regional effects of climate change on forest ecosystems in the temperate climate zone of Europe can be modelled as shifts of forest vegetation zones in the landscape, northward and to higher elevations. This study applies a biogeographical model of climate conditions in the forest vegetation zones of the Central European landscape, in order to predict the impact of future climate change on the most widespread tree species in European deciduous forests-the European beech (Fagus sylvatica L.). The biogeographical model is supported by a suite of software applications in the GIS environment. The model outputs are defined as a set of conditions -climate scenario A1B by the Special Report on Emission Scenarios (SRES) for a forecast period, for a specified geographical area and with ecological conditions appropriate for the European beech, which provide regional scenarios for predicted future climatic conditions in the context of the European beech's environmental requirements. These predicted changes can be graphically visualized. The results of the model scenarios for regional climate change show that in the Czech Republic from 2070 onwards, optimal growing conditions for the European beech will only exist in some parts of those areas where it currently occurs naturally. Based on these results, it is highly recommended that the national strategy for sustainable forest management in the Czech Republic be partly re-evaluated. Thus, the presented biogeographical model of climate conditions in forest vegetation zones can be applied, not only to generate regional scenarios of climate change in the landscape, but also as a support tool for the development of a sustainable forest management strategy.

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Clear-cut harvesting of forests may be associated with increased availability and losses of nitrogen (N), and variable-retention (VR) harvesting has been proposed as an environmentally acceptable alternative to clear-cutting. In boreal forests, however, harvesting has often not led to significant increases in N availability and it is thus important to assess whether variable retention practices are necessary and justifiable in such forests with respect to nutrient dynamics. We compared N availability in clear-cut and VR-harvested stands in the boreal mixedwood forest of northwestern Alberta. We measured soil concentrations of nitrate, ammonium, soluble organic N, and microbial N in uncut, 50% and 20% retention, and clearcuts of deciduous-dominated, coniferous-dominated, and mixed stands 4 years after harvesting. There was little apparent effect of harvesting on N availability in all forest types. Nitrate, ammonium, and microbial N concentrations and net N mineralization and nitrification rates were similar in clearcuts and uncut forests and there was no threshold effect of harvesting on N availability. Soluble organic N concentrations were lower in coniferous and mixed clearcuts than in uncut stands on only one occasion. Clear-cut harvesting in itself does not appear to lead to long-lasting increased N availability and losses in boreal mixedwoods. Adoption of VR harvesting in these ecosystems may not be justified on the grounds of reducing changes in N availability when compared with clear-cutting.

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Thorny shrubs are considered as an important driver in the natural development of temperate forest structures, particularly in European lowland forests. We assessed the current role of thorny shrubs in the regeneration of deciduous tree species under heavy browsing pressure in a central European temperate forested landscape. The study’s military training area offered a unique opportunity to investigate the processes in which deciduous tree seedlings grew under thorny shrubs and in the close vicinity of thorny shrubs in a landscape with a high density of large herbivores (red deer and sika deer). We assessed the number of seedlings, species composition, seedling height, and degree of browsing damage, and their relationship to study plots elevation, thorny shrub species, coverage, and height. The regenerated tree seedlings were mostly detected as common ash (Fraxinus excelsior) and wild cherry (Cerasus avium). The species of thorny shrubs were blackthorn (Prunus spinosa), hawthorn (Crataegus sp.), and wild rose (Rosa sp.). We found that the thorny shrubs protected the tree seedlings from browsers to a large extent. However, the effects of thorny shrubs on the tree seedlings' characteristics varied among the shrub species. While results revealed significant effects of hawthorn and wild rose on the tree seedlings' abundance and survival, blackthorn’s negative effect of shading the tree seedlings outweighed its protective role. These results indicated a possible mechanism that enabled the regeneration of deciduous tree species under large herbivore pressure. These results can be applied in the landscape planning and forest management of deciduous tree regeneration and forest restoration in temperate forested lowland landscapes, where high densities of large herbivores (without the presence of large predators) usually occur.

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