Flowering and quality of seeds and pollen in endangered populations of Betula humilis

Key message Lowered pollen and seed quality of B. humilis compared to its widespread tree relatives may threaten its populations at the southwestern edge of the species range. Abstract Inability to produce vital propagules is the main threat to the persistence of rare plants at the edges of species distribution. In the present investigation, factors responsible for the low germinability of shrub birch (Betula humilis) seeds in the peripheral populations were analysed. As shrub birch populations are found in phosphorus (P)-limited peatlands with high groundwater levels, the impact of groundwater PO43− ion contents and groundwater table for B. humilis flowering was also studied. Qualities of the B. humilis seeds and pollen were compared to those of tree congeners silver birch (B. pendula) and downy birch (B. pubescens), which usually represent a high reproductive performance. We revealed that the poor germination ability of B. humilis seeds was caused by the high proportions of empty seeds (44.8%) and seeds with partially developed embryos (47.3%). The insufficient numbers of viable seeds may be a consequence of low-quality shrub birch pollen, as only 1.6% of pollen grains sprouted. The germinability of shrub birch pollen was significantly lower than that of Betula tree pollen; thus, there is a risk of pollination of B. humilis female flowers by pollen grains of tree birches. Positive relationships between the P concentrations in seeds and seed germinability were revealed in tree birches, but not in B. humilis. The availability of PO43− ions in the groundwater did not affect B. humilis flowering, but male inflorescences were more numerous in stands with higher groundwater levels. Consequently, the maintenance of peatlands is crucial for the efficient sexual reproduction of shrub birches.

Epicuticular wax lipid composition of endemic European Betula species and its application to chemotaxonomy and paleobotany

Plants, in particular trees with specific habitat demands are excellent indicators of climate state. Vegetation successions in subrecent and deep geologic time is recorded in fossil macro-remains or pollen accumulating in geological archives like limnic and marine sediments, peat bogs and mires. Birch trees in Europe form a major part in plant successions and constitute the dwarf species Betula nana and Betula humilis representing cold-adapted habitats or climates and two tree birches, Betula pubescens and Betula pendula characteristic for temperate habitats or climates. These birch species exhibit highly similar pollen shape and size, preventing their unambiguous application as paleoclimate/paleovegetation proxies. We here present a chemotaxonomic differentiation of the four European birch species based on their epicuticular wax lipids. The dominating lipid classes in epicuticular birch waxes were found to be n-alkanes (in the range of n-C23 to n-C33), straight-chain primary alcohols and fatty acids (in the range of n-C20 to n-C32), and long-chain wax ester (in the range of n-C38 to n-C46) in variable amounts and distributions. When preserved in geological archives these lipids may serve in paleovegetation/paleoclimate reconstruction. Long-chain wax esters are susceptible to hydrolysis and upon diagenesis the release of ester-bound alcohols and fatty acids may modify the distribution pattern of the corresponding primary free lipids. Quantitative analysis of the hydrolyzable wax ester proportion revealed primary distribution patterns of birch lipids not to change substantially upon release of bound analogues. The specific composition and abundance of epicuticular wax lipids facilitates unambiguous chemotaxonomic separation of the four European birch species. Wax lipid-based discrimination in field application, however, is complicated by mixing of alkyl lipids derived from different birch species and contribution of wax lipids from other plants. In cases, where palynology indicates a high contribution of Betula species to European vegetation associations, wax lipids may serve for differentiation of the species contributing.

Stanowiska reliktowego gatunku Betula humilis (Betulaceae) w Dolinie Górnego Nurca na Nizinie Północnopodlaskiej

Betula humilis Schrank (shrubby birch) is among the most endangered shrub species in Poland. All localities are in the eastern and northern parts of the country, where the species reaches the western border of its geographical range in Europe. Betula humilis is disappearing in Poland due to wetland melioration and shrub succession. Over 80% of the localities described in Poland have not been confirmed in the last 20 years. Five new localities of B. humilis in the North Podlasie Lowland were recorded from 2008 to 2019 in the Upper Nurzec Valley (Fig. 1): 1–1.5 km south-west of Pawlinowo village (in the ATPOL GC7146 plot) and 1.5–2 km north-west of Żuki village (ATPOL GC7155, GC156 and GC166). The population near Pawlinowo (locality 1) is currently composed of ~80 individuals (101 individuals were noted in 2010) and is one of the largest populations in north-eastern Poland. Betula humilis grows there within patches dominated by Salix rosmarinifolia and megaforbs. The population at locality 5 is composed of 18 individuals. At the remaining localities, only 1–4 individuals were found, scattered along drainage ditches surrounded by hay meadows. At some of these localities the species is threatened with extinction. It is suggested to remove competitive trees and shrubs (mainly Populus tremula, Betula pubescens and Salix cinerea) in order to maintain the local populations.

To What Degree Can the Specifics of Occurrence of Glacial Relic Betula humilis Schrank Be an Indicator of Habitat Conditions of Moderate Climate Peatlands?

Anthropogenic transformations of habitat conditions in moderate climate peatlands frequently cause a decrease in the number of sites of occurrence and the size of the population of many valuable plant species, including the boreal relic Betula humilis. The objective of this paper was an attempt to relate the specifics of the occurrence of the glacial relic Betula humilis in the peatlands of Central-Eastern Poland, which developed under moderate climate conditions, to the conditions of the natural environment identified through research into the physical and chemical parameters of the groundwater, as well as botanical research into its habitat. The study results confirm that shrub birch has a broad range of ecological tolerance to the majority of the studied factors and can therefore be an indicator of habitat transformation. Important environmental factors affecting its abundance are water relations and the contribution of calcium hydroxide and phosphorus fractions. A condition favouring the proper functioning of individuals of the studied species is TP values lower than other obtained values, in the following range: 0.08–0.32; P-PO4: 0.1; TN: 2.2–21.2; N-NH4: 0.1–0.46; DOC: 24.6–55.9 (mg·dm−3), as well as higher than average pH values, in the following range: 5.34–5.95; Ca: 5.67–28.1; Mg: 0.56–2.41 (mg·dm−3) and EC: 72.1–142.3 (µS·cm−1).

Флористичні особливості гідрологічного заказника місцевого значення «Оріхівський» Ратнівського району Волинської області

У статті проаналізовано флору гідрологічного заказника місцевого значення «Оріхівський» Ратнівського району Волинської області. Основним завданням роботи було встановлення сучасного стану флористичного та фітоценотичного різноманіття гідрологічного заказника місцевого значення «Оріхівський» і виявлення на його території рідкісних та зникаючих видів флори, занесених до Червоної книги України й інших природоохоронних документів. У статті проаналiзовано аспекти становлення та розвитку флористичних досліджень заказника, подано опис фітоценотичного різноманіття. На території заказника виявлено види з Європейського червоного списку: Crataegus uсrainica Pojark., Silene lithuanica Zapał. Tragopogon ucrainicus Artemcz.; види, занесені до Додатка № 1 Бернської конвенції: Aldrovanda vesiculosa L, Cypripedium calceolus L. Liparis loeselii (L.) Rich, Pulsatilla patens (L.) Mill.; види з Червоної книги України: три зникаючі, п’ять вразливих, шість рідкісних видів на території, серед зникаючих видів потрібно відзначити Huperzia selago, Oxycoccus microcarpus, Scheuchzeria palustris, із-поміж вразливих – Cephalanthera rubra (L.), Drosera anglica Huds, Epipactis helleborine (L.) O. Kuntze, Lilium martagon L., Lycopodiella inundata (L.) Holub., серед рідкісних – Betula humilis Schrank, Listera ovata (L.) R.Br., Neottia nidus-avis (L.) Rich., Platanthera bifolia (L.) Rich., Salix myrtilloides L., Salix starkeana Willd.

РАСТИТЕЛЬНОСТЬ БОЛОТНОЙ СИСТЕМЫ ЯМНИЦКАЯ ЧИСТЬ (ЛЕНИНГРАДСКАЯ ОБЛАСТЬ), "Ботанический журнал"

Приводятся результаты первичного исследования болотной системы Ямницкая Чисть, а также ближайших ее окрестностей, осуществленного авторами статьи в 2015 г. Ранее опубликованные сведения с описанием этой территории отсутствовали. Болотная система Ямницкая Чисть расположена на юго-востоке Ленинградской обл. (Бокситогорский р-н) в границах планируемой к созданию одноименной особо охраняемой природной территории (ООПТ) регионального значения, занимая основную ее площадь. Особенности болотной системы обусловлены положением на наклонной поверхности равнины, примыкающей с юга к Вепсовской возвышенности, а также, по-видимому, обширными торфяными пожарами в прошлом. Слагающие болотную систему разнотипные болотные массивы, среди которых встречаются редкие для Ленинградской обл. типы болот, имеют заметный уклон поверхности, что отражается на ландшафтной структуре и характере растительного покрова. Болотная система окружена лесами, эталонными для юго-востока Ленинградской обл. и представляющими весь спектр южнотаежных лесных ассоциаций. На территории болотной системы и в окружающих ее лесах обнаружены редкие виды сосудистых растений, мхов, лишайников и грибов - Betula humilis, Epipogium aphyllum, Pulsatilla patens, Sphagnum palustre, Pylaisia selwynii, Heterogemma laxa, Lobaria pulmonaria, Hericium coralloides и др.