We present some results of a six-year (2008-2013) study in two localities of Liparis loeselii (L.) Rich. near Lake Engure. The annual cycle of L. loeselii, an early successional species, may indicate its potential survival in its typical wet habitat with fluctuating levels of water. Flowering of L. loeselii usually begins in the first decade of June and lasts for several weeks. If the initiation of development was delayed, leaves and inflorescence started to grow almost simultaneously. Development of the first fruit began during flowering and continued to August. Ripening of fruit and seeds occurred in September-October, and they were dispersed mostly by melt water of snow in spring, which is very important for populations in sites overgrowing with perennial herbs. The previous season capsules of L. loeselii remained till the middle of the next growing season; a part of the seeds remained in capsules and less than 1% of seeds had viable embryos. This may increase the survival potential of the population. The studies of herbarium records of L. loeselii in the area of Lake Engure showed that the annual cycles of L. loeselii have been similar and that the species has not responded drastically to climate change.

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The Eastern pasqueflower (Pulsatilla patens (L.) Mill.) is considered as an endangered species in all European countries where it is found, including Latvia. An important factor for the survival of P. patens - a species with low competitiveness is not only the conditions suitable for germination and further growth, but also the indicators of seed viability. This is particularly important as there is no persistent soil seed bank for this species. Only limited data is available on the factors affecting seed viability, especially in the terms of soil conditions. Therefore, the main goal of this study was to find out the potential relationship between seed viability and soil agrochemical composition in 8 different locations of P. patens in Latvia. Demographic parameters were also analyzed as factors that could lead to differences in seed viability between populations. Overall, there were almost no substantial differences between study sites in terms of the seed production per one infructescence of P. patens. However, significant differences were found in seed viability data, with the percentage of viable seeds ranging from 2.1% to 53.8%. The results revealed a significant positive correlation between seed viability and concentrations of Ca and Mg in the soil. Our study suggested that one of the factors that positively affect seed viability could be the higher micronutrient (B, Cu, Fe) level in the topsoil. In addition to the wide range of nutrient concentrations in the soil, the studied sites also differed according to the demographic characteristics of the populations. Preliminary results showed that populations with a higher proportion of new generative plants had higher levels of viable seeds. This was convincingly evident in the nearby sample plots. Comparing the two adjacent areas, it was found that new generative plants dominated in those where the values of at least two soil parameters, such as Ca, Mg, organic matter, Cu and Fe, were higher. Further research is needed to better understand the relationship between soil conditions, population demographics and seed viability, thus contributing to the development of protection measures for P. patens in Latvia.

Dianthus superbus is one of the most endangered species in Latvia and is on the verge of local extinction. Therefore, the aim of this study was to inventory previously identified populations of D. superbus in Latvia and to develop activities to conserve this species in accordance with the results obtained in situ. Expeditions on 18 previously documented locations, according to the data of Nature Conservation Agency, revealed only 3 existing D. superbus localities in Latvia with a significant number of specimens located in the Latgale region near Silenieki. In 2020, for the first time, two more new D. superbus localities were found in the vicinity of these 3 approved locations. As it is not possible to create micro-reserves in the existing localities which are mainly located either on roadsides or in a cemetery, additional activities are needed to preserve the D. superbus in Latvia. In vitro culture was initiated from shoot explants obtained in situ, from which, in turn, ex vitro plantings were done in the National Botanic Garden (NBG) and the Botanical Garden of the University of Latvia (BG UL). Their quality and compliance with plants in situ were analysed. Overall, it was concluded that the plants grown ex situ were qualitatively equivalent to those obtained in situ, as a very high percentage of seed viability and germination was found both for in situ and ex situ growing D. superbus. Based on the results obtained we could conclude that D. superbus is a species that is able to adapt to different soils with a wide range of nutrient levels, moisture conditions and pH, as long as there are three main preconditions - adequate lighting, low overgrowth of other plant species, and non-destructive human activities.