Climate change can influence the distributions of species and communities in mountain environments, but responses may differ among vegetation belts and may be strongly modified by local habitat conditions. Although distributional shifts have been studied widely, much evidence comes from alpine and arctic environments, while detailed resurvey studies focusing on individual species across broader elevational gradients remain comparatively rare. Here, we compared past (2000-2002) and current (2019) distributions of two closely related grasses in the Giant Mountains (Czech Republic): Anthoxanthum odoratum (an allotetraploid primarily of lower elevations) and A. alpinum (a diploid occurring mainly at higher elevations). We assessed changes in their occurrences over two decades and tested which environmental factors were associated with current occurrence, appearance and disappearance. Overall, elevational ranges changed only modestly, with weak evidence that A. odoratum now occurs at slightly higher elevations than in 2000-2002. A. alpinum also appeared at a small number of lower-elevation sites. Changes in occurrence were associated with local habitat characteristics (vegetation and bryophyte cover, nutrient and soil moisture indicator values, and community composition) and were largely independent of elevation as a broad proxy for macroclimate. These results suggest that fine-scale habitat context is a key correlate of distribution and recent distributional dynamics in this species pair.
Effects of topography on the composition of trees and seedlings have been demonstrated in many tropical forests. Less attention has been paid to interannual changes in seedling establishment as a potential driver of the species composition. We explored the associations of neighbouring vegetation physiognomy and the abiotic environment (mainly topography) with the composition of tree seedlings. To reveal the shifts in habitat preferences through ontogeny, we compared the compositional response of tree composition to the same abiotic variables. Further, we evaluated interannual differences in seedling composition and composition of newly recruited seedlings. Seedling composition was monitored in 800 permanent quadrats within the 50 ha forest dynamics plot in the lowland tropical forest in Papua New Guinea for five consecutive years. Redundancy analyses were used to reveal the effects of abiotic and biotic factors on the composition of trees and seedlings. The ridge-valley position and the slope steepness were associated with the distribution of seedlings and even more so of trees. The effect of neighbouring vegetation physiognomy on seedlings was negligible. We found mostly concordant responses of established trees and their seedlings to the ridge-valley gradient, although some species exhibited preferential shifts during their ontogeny. The species composition of seedlings varied significantly over consecutive years. Topography appears to shape the species composition with varying strength depending on the species identity and through the ontogeny of individual trees. Strong interannual variation in the distribution and identity of newly recruited seedlings can contribute to the maintenance of local tree diversity.
The present study provides a detailed macro- and micro-morphological and anatomical description of seeds of 13 Cistaceae taxa (two Fumana and 11 Helianthemum), some of which are presented here for the first time (the near-endemic H. crassifolium subsp. sphaerocalyx and the rare H. sancti-antoni, H. sessiliflorum, H. vesicarium, and Helianthemum virgatum subsp. ciliatum). The seed shape, size, texture, hilum characteristics, epidermal cell patterns, anticlinal and periclinal cell walls, seed-coat ultrastructure, and the shape, thickness, and arrangement of different seed-coat layers were comparatively examined using light and scanning electron microscopy methods. The taxonomic significance of these characteristics is discussed, and a determination key using seed morphological and anatomical attributes is presented. Multivariate analyses of seed characters compared the previous and current sectional classifications of the two studied genera. Based on seed morphological and anatomical traits, our results support inclusion of H. aegyptiacum in sect. Helianthemum. This finding agrees with recent systematic treatments of the genus. Moreover, our results support the treatment of H. sessiliflorum as a distinct species, rather than a synonym of H. lippii.
Forest road verges are common secondary habitats in managed forest landscapes, however their vegetation development remains insufficiently documented. We investigated the successional changes in ground vegetation on newly built forest road verges in Latvia over an eight-year period using six repeated surveys, analysing the taxonomic diversity of vascular plants and bryophytes, their ecological indicator values, Rao’s quadratic entropy as a measure of niche differentiation, and the functional trait composition of vascular plants based on Grime’s CSR strategies and Raunkiær’s life forms. Our results showed a continuous increase in taxonomic richness throughout the study period, whereas niche differentiation increased mainly after the first year following road construction and remained relatively stable thereafter. Regarding the examined ecological indicator values, nutrient availability consistently showed the highest niche differentiation, whereas light and moisture showed comparatively lower variation. Functional composition shifted from ruderal-dominated communities to an increasing representation of stress-tolerant and competitive vascular plant species. The results from the mixed-effects models revealed high spatial variation among road sections, indicating that early secondary succession on forest road verges is shaped by both successional processes and local environmental conditions.
The flowers of members of the Capparaceae are characterized by an open morphology with numerous stamens, suggesting generalist pollination systems. Despite the conservative nature of this floral form within the family, there is evidence of significant variation in other traits, as indicated by sporadic records of different pollination systems. The research on the pollination biology of the Capparaceae seems to be sparse and fragmented, revealing an Eltonian shortfall in relation to plant–animal interactions in this family. Our objectives were: (1) to compile information from the literature on floral traits and pollination systems in the Capparaceae; (2) to summarize current knowledge about reproductive systems in the Capparaceae; (3) to test the existence of a latitudinal gradient in functional and ecological specialization within the family; and (4) to identify priority areas and species for further studies on pollination. We found considerable variation in floral traits, including colour, size and the number of stamens. Our results show a high degree of functional specialization, with the largest species being pollinated mainly by bees. We observed differences along a latitudinal gradient: Whereas the richness of pollinators reaches the peak near the equator, specialized groups, such as bats and moths, are restricted to tropical zones, making extratropical species more dependent on widespread pollination by bees. Variations in reproductive systems, including changes between self-incompatibility and self-compatibility, suggest a high degree of reproductive plasticity in response to environmental pressures and the scarcity of pollinators. We emphasize the need for further research on pollination ecology in Africa and South America, where many species of the Capparaceae are at risk of extinction.
