Rūrāne I., Evarts-Bunders P., Nitcis M., 2018: Distribution trends of some species of the Brassicaceae family in Latvia. - Botanica, 24(2): 124-131. The aim of this paper was to clarify and analyse the distribution trends of some Brassicaceae species (Bunias orientalis, Sisymbrium volgense, Barbarea arcuata, Draba nemorosa and Camelina alyssum) in Latvia. Field studies and the herbarium material analyses were carried out. The distribution trends were analysed by comparing all selected species in three time periods: by 1940, from 1941 to 1990, and from 1991 to the present. The study shows that the distribution of Brassicaceae species such as Bunias orientalis, Sisymbrium volgense, Barbarea arcuata and Draba nemorosa has increased significantly in Latvia during the time period from 1991 to the present, and these species are mostly found on railway, ruderal areas and roadsides, which are important habitats for species distribution. The occurrence of Camelina alyssum has considerably declined or perhaps the species has even disappeared from the flora of Latvia, which has been affected greatly by changes in the cultivation of agricultural crops as well as in agricultural land management.

1. Organisms that depend on rare and endangered microhabitats, such as old, hollow trees, have a high conservation value.2. To conserve these species, it is necessary to apply methods that identify habitats suitable for their survival.3. Until now, a comprehensive method has not been developed for predicting the occurrence of species associated with old, hollow trees.4. Here, we developed criteria to identify habitats for organisms associated with old, hollow trees, using Osmoderma barnabita as a model species.5. We used hexagonal tessellation to identify suitable habitats for hermit beetle. 6. Criteria for predicting the occurrence of a hermit beetle were applied in practise, and as result 47.56% of the known hermit beetle localities coincided with the hexagons where the probability of occurrence of the species was the highest. Based on these results, an ecological network was created for species dependency on old, hollow trees, using the hermit beetle as a model species.7. The proposed approach makes it possible to plan and implement environmental protection measures for species living in territories spanning several countries. In this work, we propose a method to identify species occurrence in core areas and to determine ecological corridors and gaps. This method could tailor conservation planning efforts.

Forest landscape plays a significant role in rare cryptogam distribution. However, data about the environmental demands of rare epiphytic bryophytes and lichens in boreo-nemoral forest landscapes are not complete. In this study, we focused on finding the main environmental predictors influencing the occurrence of three red-listed epiphytic bryophytes and three red-listed epiphytic lichens in the Latvian boreo-nemoral forest landscape. We obtained the records of species from the Natural Data Management System OZOLS database, which is a national information system on all rare taxa. We analyzed the occurrence of species in relation to forest stand age and area, forest type, heterogeneity and tree bark pH class. We found that selected red-listed bryophyte and lichen occurrence was mainly influenced by forest stand age and area. However, each of the red-listed epiphytic bryophyte and lichen has their own ecological demands in the boreo-nemoral landscape.

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Dytiscus latissimus (Coleoptera Dytiscidae) is an endangered diving beetle throughout its range. It is one of the two species of Dytiscidae listed in Annex II of the Habitats Directive, IUCN red list and in many national level legislations and therefore strictly protected. The conservation of endangered species first of all requires an assessment of their population size. Until now, a method has not been developed for estimating the size of D. latissimus populations. The article summarizes the results of two studies carried out independently in Germany and Latvia. Both studies were carried out in one water body used recapture method but with a different spatial placement of traps, which, according to our data, is an important factor in population estimation. We evaluated Jolly-Seber and Schnabel approaches of estimating aquatic beetle's populations and found that confidence intervals obtained by different methods in our research do not differ significantly, but combination of both models provide the most accurate estimates of population dynamics. As part of the study, we concluded that the populations of Dytiscus latissimus are relatively closed, so we accept that the Schnabel estimate shows more accurate data. By fixing the places of capture of each individual, it was found that females live mainly locally, and males actively move within the water body. This aspect indicates the advantage of the spatial placement of traps compared to the use of transects. The results of our study show a significantly higher number of both captured and recaptured males Such a sex ratio may indicate both a greater activity of males and differences in the sex ratio in the population. The study confirmed that environmental changes, such as the water level in a water body, can also significantly affect the result of a population assessment. In the frame of D. latissimus monitoring, to obtain an objective estimation of the species population size we recommend using four traps for each 100 m of water body shoreline with 4–8 censuses, dependently on the recapture rate.