Katarzyna M. Zielińska

Regional climate and geology affecting habitat availability for a relict plant in a plain landscape: the case of Festuca amethystina L. in Poland

Background: The distribution of refugial habitats is the main factor affecting the existence of cold-adapted species in the lowlands. In addition, regional climatic conditions could have an influence on relicts. Aims: Co-occurrence of environmental factors in the determination of the distribution of the glacial relict Festuca amethystina was examined in Poland. Methods: Climatic data, habitat indicator species, parent material of soils and range of glaciations were analysed, using ecological niche modelling. Prediction of Festuca amethystina occurrence for different sets of data – only climatic, only habitat and all data – was modelled. Results: The distribution of Festuca amethystina was related to the presence of oak forests (Potentillo albae-Quercetum), to moderate subcontinental climate, but not to the distribution of loess soils. In addition, variables related to temperature and precipitation in the driest quarter of the year, isothermality and a mean diurnal range had the strongest influence on the occurrence of F. amethystina within the Potentillo-Quercetum range. Conclusions: Climate acts as a regional filter and habitat availability as a local filter for distribution of the species. Therefore, the habitat can act as microrefugium in some parts of its range. In a flat landscape, relicts can persist where environmental conditions are simultaneously favourable for the persistence of refugial vegetation and relict populations.

The relationship between climatic conditions and generative reproduction of a lowland population of Pulsatilla vernalis: the last breath of a relict plant or a fluctuating cycle of regeneration?

The alpine-boreal plants which have survived in Central European lowlands during glacial periods depend both on the preservation of their refugial habitat, and their capability for vegetative and generative reproduction and dispersion. Pulsatilla vernalis (L.) Mill. is a model species which occurs throughout most of the European alpine system, as well as in isolated populations in the lowlands. At present, the relict lowland localities of this species often have a historic character. In the Polish lowlands, only the population located in Rogowiec is characterized by effective recruitment. It presents a large number of rosettes and a diversified demographic structure, with plants in all stages of development. The study examines the population in Rogowiec from 2002 to 2008 with regard to the number of flowering and fruiting shoots, new seedlings, and loss of juvenile rosettes, and the obtained data are correlated with climatic conditions. Three years were found to demonstrate effective recruitment, with numerous seedlings and little loss of juvenile rosettes. No significant relationship was found between seedling dynamics and the flowering–fruiting process. However, correlations were found between effective renewal and some climatic factors. Temperature, water balance, and solar radiation were found to have a limiting effect on the reproduction and regeneration of the analyzed relict population. Due to the longevity of the rosettes, favorable climatic conditions occurring every few years are sufficient for survival of the species in this location. However, serious threats are posed by the climate change trends expected in Europe over the coming decades, and the fact that due to its small-scale dispersal ability, the analyzed species occupies only a small area in Rogowiec.

Forest roadsides harbour less competitive habitats for a relict mountain plant ( Pulsatilla vernalis ) in lowlands

The long-term survival of relict populations depends on the accessibility of appropriate sites (microrefugia). In recent times, due to the mass extinction of rare species that has resulted from the loss of natural habitats, the question is – Are there any human-made sites that can act as refugial habitats? We examined forest roadside populations of the mountain plant Pulsatilla vernalis in the last large lowland refugium in Central Europe. We compared the habitat conditions and community structure of roadsides with P. vernalis against the forest interior. Light availability and bryophyte composition were the main factors that distinguished roadsides. Pulsatilla occurred on sites that had more light than the forest interior, but were also more or less shaded by trees, so more light came as one-side illumination from the road. Roadsides had also a lower coverage of bryophytes that formed large, dense carpets. At the same time, they were characterised by a greater richness of vascular plants and ‘small’ bryophytes, which corresponds to a higher frequency of disturbances. In a warming and more fertile Anthropocene world, competition plays the main role in the transformation of forest communities, which is why relict populations have found refugia in extensively disturbed human-made habitats.

TRANSFORMATION OF FOREST VEGETATION AFTER 40 YEARS OF PROTECTION IN THE TOMCZYCE NATURE RESERVE (CENTRAL POLAND)

Transformation of Forest Vegetation After 40 Years of Protection in the Tomczyce Nature Reserve (Central Poland) The Tomczyce nature reserve is characterized by a degenerated forest vegetation. We assume that the regeneration process was possible to launch after the establishment of the nature reserve in 1968. The vegetation of the Tomczyce forest complex was characterized for the first time by Jakubowska-Gabara (1976) whose studies were taken as a basis of our research. The phytocenoses after 40. years of protection have a greater participation of species with higher trophic and moisture requirements. The regeneration process in communities with pine trees is caused by an expansion of broad-leaved trees and shrubs. Transformation of forest vegetation causes a decrease in cover of thermophilous and heliophilous species. On the other hand, species of oak-hornbeam forests as well as anthropophytes are in expansion. Planning of the protection activities in the nature reserve needs to include these dynamic tendencies of the vegetation.

How do ditches contribute to bryophyte diversity in managed forests in East-Central Europe?

The study focuses on identifying and assessing the effect of the presence of drainage and roadside ditches on the diversity of bryophytes in managed forests. We compared the composition of moss and liverwort species, their richness and abundance in plots that are located in ditches as well as corresponding control plots in the surrounding forests with regard to the forest type (coniferous, mixed and deciduous). ANOVA demonstrated the pronounced impact that the presence of ditches in managed forests has on an increase in bryophyte species richness. A comparison of forest and ditch types using DCA pointed to a correlation between the number of deciduous trees in the stands and an increased dissimilarity of ditch bryophytes when compared to the bryophytes of the corresponding control plots. Using the ecological indicator values, CCA confirmed the special significance of ditch settlements for hygrophilous species, which at present cannot otherwise find favorable conditions in managed forests. The study proves that ditches, and especially those with intermittent pools of stagnant water, may become a significant source of microhabitat diversity. Their presence may provide a welcome preserve for rare and protected species that cannot find suitable substrates in managed forests.

Habitat and spatial thinning improve the Maxent models performed with incomplete data

Species distribution models need adequate sets of data, particularly in the case of range-restricted species. The problem faced in the modeling of rare species is twofold: a small sample size and the occurrence of sampling biases. The present analysis combines spatial- and habitat-thinning approaches to improve maximum entropy models based on geographically incomplete data of relict and subendemic Festuca amethystina L. grass on Polish territory. The results show that models based on strongly incomplete historic data did not predict the occurrence of all important areas where the species was found in the following decades. However, the introduction of species-specific thinning allows for more precise prediction of the species range, i.e., the detection of suitable areas on a more local scale. The introduction of habitat thinning caused the diversity of important predictors in model to increase, but spatial thinning decreased the number of significant predictors and made interpretation easier. Additionally, a combination of thinning techniques allowed significant improvements to be made to the model predictions after the experimental addition of a lower number of localities to regions which had previously been poorly recognized. It can be concluded that in the case of incomplete data, the above corrections allow the true range of the species to be predicted after the discovery of a lower number and relatively dispersed new localities.

Refugial debate: on small sites according to their function and capacity

The occurrence and location of long-term refugia determine the current patterns of biodiversity on Earth. The importance of the refugial debate is certain to increase in response to observed and expected species extinctions caused by climate change. Small areas where species survive outside their core range are important, as unique natural phenomena and model systems for observing the response of species to climate change. They can play a crucial role as potential sources for species recovery in the future or can act as progenitors of a new species. While most authors believe that sites connected with only long-term isolation should be included into the refugium concept, this approach can result in the loss of linkage between the ecological and evolutionary processes taking place during different phases of the species range dynamics. Moreover, the papers often interpret the nature of described phenomena in different ways. In response, the conceptual scheme given in our letter summarises the patterns which occur during species range shift. It proposes an equivalent scheme for small refugial sites according to their function and capacity, based on the relict species concept. This approach and proposed terminology is tested on the example of two plant species with different pattern of the long term range dynamics. Our paper highlights the importance of sites harboring ‘trailing-edge’ young relicts for the future long-term persistence of the species (as old relicts) under unfavorable regional conditions. By considering the age gradients of small refugial sites it is possible to reveal community interactions, species traits or genes that drive the responses of biota to climate changes.

Morphometric traits in the fine-leaved fescues depend on ploidy level: the case of Festuca amethystina L.

Background Polyploid specimens are usually characterized by greater exuberance: they reach larger sizes and/or have a larger number of some organs. Festuca amethystina L. belongs to the section Aulaxyper. Based on morphological features, four subspecies of F. amethystina have been already identified. On the other hand, it has two cytotypes: diploid and tetraploid. The main aim of our study was to distinguish morphological differences between the cytotypes of F. amethystina, assuming that its phenotype differs significantly. Methods The nuclear DNA content was measured by flow cytometry in dry leaves from specimens originating from 13 populations of F. amethystina. Several macrometric and micrometric traits of stems, spikelets and leaf blades were taken into account in the comparative analysis of two cytotypes. Results In the case of cytotypes, specimens of tetraploids were larger than diploids. The conducted morphometric analysis of leaf cross-sections showed significant differences between the cytotypes. Discussion The research has confirmed for the first time that in the case of F. amethystina the principle of greater exuberance of polyploids is true. Differences between the cytotypes are statistically significant, however, they are not enough to make easy the distinction of cytotypes on the basis of the measurements themselves. Our findings favor the rule known in Festuca taxonomy as a whole, i.e. that the ploidy level can be one of the main classification criteria.