Two Potamogeton species (Potamogetonaceae) new to the Caucasus

A revised lichen catalog for Georgia, the South Caucasus, the second after 1986, is presented here. It is based on a literature survey and recent study of herbarium material. The list includes 713 species of lichens and nine species of nonlichenized fungi traditionally treated by lichenologists. As a basis for the present catalog, 106 literature sources reporting the first findings of the listed taxa in floristic regions of Georgia were used. The accepted taxa in bold are followed by references from the literature, if applicable, as well as references from herbarium specimens seen by us at local and several foreign herbaria. Specimens of the 547 of the 722 reported species are stored in the local herbaria: 542 at the National Herbarium of Georgia, the Institute of Botany, Ilia State University, Tbilisi (TBI), and 94 in the Herbarium of the State Museum of Georgia, Tbilisi (TGM). In each literature citation and herbarium code, the occurrence of respective species in Georgia’s floristic regions is given. In addition, a short historical background and comprehensive bibliography are provided.

The results presented in this study provide updated information on diversity and distribution of aquatic plants in West Georgia, mostly on new floristic records. During the studies in 2022 and 2023, two non-native species of South American origin were identified. Azolla filiculoides is reported for the first time for Georgia and southwestern Caucasus with its presence known in two coastal waterbodies in Adjara and Guria, however its status remains uncertain. Another non-native species, Elodea densa, which has been spreading in the region since the 1970s from the Batumi Botanical Garden, has become invasive and widely distributed along the coastal water bodies of the Kolkheti Lowland, often dominating in macrophyte communities. As the information on the distribution of E. densa in Georgia was highly generalized, additional records and field observations have been provided. Examination of herbarium materials from the region has also allowed to exclude from the flora of Adjara Elodea canadensis, a similar species previously reported in the Batumi Botanical Garden. Three additional species native to the Caucasus flora, Najas major, Potamogeton nodosus, and Zannichellia pedunculata, are reported for the first time for southwestern regions of Georgia. Najas major is a species new to the South Caucasus.

In Brazil, although, high-altitude shallow lakes comprise large parts of conservation units and are considered highly important environments for biodiversity studies, little is known about the factors that regulate the zooplankton community. In the present study, we sought to identify the effect of regional (hydroperiod and altitude) and local (lake area and macrophyte cover) factors on the zooplankton communities in eight shallow high-altitude lakes (from 1080 m a.s.l. to lakes above 1200 m a.s.l.) in the Espinhaço Mountain Range (Brazil). Of the 116 zooplankton species identified, 66 (56%) showed a high degree of spatial aggregation, occurring in only a few lakes. Accessory species occurred predominantly in small lakes, while rare species were better represented in the larger lakes, suggesting species sorting associated with the niche effect. Zooplankton richness was strongly influenced by hydroperiod, indicating that temporary lakes can congregate species resistant to the environmental filter of the drought, playing an important role in the diversification of the zooplankton community. We identified environmental heterogeneity (macrophyte cover) as the factor that most influenced the species diversity: zooplankton responded positively to increased macrophyte cover, confirming that the presence of aquatic plants constitutes a strong environmental filter to explain the variation of the zooplankton community. Zooplankton species composition and abundance differed among lakes, indicating a certain degree of heterogeneity in assemblage structure, but no influence on zooplankton diversity was observed. Our results provide evidences that altitude did not influence zooplankton diversity and this may affect the regional diversity (ß diversity) of tropical high-altitude lakes, and merits further study.

Muchas especies de briófitas tropicales crecen en habitats periódicamente inundados como lechos del río, pantanos y cascadas, pero se presentan pocos briófitas sumergidas permanentamente y están más que todo en lagunas de alta montaña. Su identificación podría ser dificil por la modificación de rasgos inducidos por el medio acuático. Aquí se trata de una población sumergida del género Herbertus de las hepáticas de una laguna glaciar a 4120 m en la Sierra Nevada del Cocuy, Colombia. Las plantas acuáticas caracterizadas por el porte enano y los apices obtusos de las hojas. Se ha identificado como H. oblongifolius, un taxon raro descrito de Brazil y recientemente, basado en la morfología, ubicada como sinónima de la especie variable, H. sendtneri, de distribución amplia. Análisis molecular ha confirmado que las plantas acuáticas pertenecen a H. sendtneri. La semejanza de las plantas acuáticas con las ramitas de H. sendtneri parece de sugerir un fenótipo juveníl. Las plantas acuáticas probablemente tienen su origen en una población en las rocas y lajas cercanas y han llegado a la laguna a través de ramitas vegetativas caedizas y así traidas a la laguna por el viento y el agua, o plantas enteras entraron a la laguna con lluvias fuertes inundando las lajas. © 2018. Acad. Colomb. Cienc. Ex. Fis. Nat.

Monitoring water spread and aquatic vegetation using earth observational data for Nani-High Altitude Lake (N-HAL) of Uttarakhand State, India

Large 13C enrichment in primary carbonates from Andean Altiplano lakes, northwest Argentina

The paper is dedicated to the surface water resources of Azerbaijan and their efficient use. Azerbaijan is in the list of the countries with small water supply. Compared to the other countries of the South Caucasus, the water resources of Azerbaijan are limited and comprise only 15 % of water resources of the whole region. The water percent per head of the population in Azerbaijan is on the lowest level compared to the other Republics. The main reason for this is various locations of water sources. The estimated reserves of water in our country are equal to 30.9 bln. m3, of which 33 % is local, and 66 % - the water formed due to the transborder rivers. The contamination of Araz and Kur rivers, the major water sources, by the neighboring states worsens the situation. To meet the demand of the crop plants in irrigation water, the amount of the agricultural water should be increased. Therefore, the supply of farm lands with water is directed to the implementation of the different water-related activities, as well as to the engineering-melioration and other organizational issues with the purpose of rational use of the water.

Notes on the taxonomy of Nymphaeaceae and Menyanthaceae in Mongolia

Leaf dimension, degree of leaf rolling or folding, and stomatal densities on adaxial and abaxial leaf surfaces were measured on herbarium specimens of 39 grass species from a range of dry to wet habitats in western Canada. Stomata were counted on vinyl leaf impressions taken from the herbarium specimens. Representative surfaces also were examined using scanning electron microscopy. All species from dry habitats had narrow rolled or folded leaves (4 mm or less). The proportion of stomata on the abaxial surface of species from dry habitats ranged from 0 to 65%, but 56% of the species were strongly amphistomatous. The results were compatible with a conceptual model predicting that rolling, amphistomatous leaves would be selected for habitats in which water supply and demand fluctuate widely on seasonal or diurnal time scales. The evolutionary adaptation of grasses involves a syndrome of physiological, anatomical, and morphological characteristics. Grass leaf structure is closely coupled with major physiological processes such as photosynthesis, water relations, and energy balance. For example, vascular bundle and mesophyll cell arrangement are related to the type of photosynthetic pathway (Black et al., 1973; Hattersley & Watson, 1975), which, in turn, can influence niche separation in grasses (Monson et al., 1983). Specialized leaf tissue structure in some grasses results in leaf rolling, which strongly influences water and energy balances by changing the characteristic leaf dimension and the conductance of heat, water vapor, and carbon dioxide (Ripley & Redmann, 1976). This paper concentrates on the relationship between leaf rolling and stomatal distribution and conductance. The anatomy and mechanism of leaf rolling in grasses have been studied for over a century (Tschirch, 1882; Shields, 1951). Loss of turgor in the bulliform cells on the adaxial (upper) surface generally is considered to induce rolling. Shrinkage of the adaxial subepidermal sclerenchyma and mesophyll, due to water loss, also contributes to involution; rolling can occur in leaves that lack bulliform cells (Shields, 1951). Some grasses have permanently rolled or folded leaves. Leaves of native grasses from semi-arid grassland roll in response to increased plant water stress during dry periods (Ripley & Redmann, 1976). More mesic grasses such as cereal crops also exhibit leaf rolling when exposed to water stress (Hurd, 1976; O'Toole et al., 1979). Leaves of Sorghum bicolor roll and unroll in response to diurnal changes in plant water status, provided stress is not too severe (Begg, 1980). The early textbooks on plant ecology generally explained rolling as a xeromorphic adaptation for reducing transpiration by protecting the stomata, which were considered to be concentrated on the upper surface (Warming, 1909; Weaver & Clements, 1929; McDougall, 1949). Unfortunately, references to data supporting this explanation were not given, but the idea probably originated with early work on ecological plant anatomy. Tschirch (1882) classified grasses as meadow type, with flat leaves, or steppe type, with rolling leaves. Lewton-Brain (1904) grouped British grasses into four categories representing progressively more drought resistant types: (1) leaves with flat upper surfaces, amphistomatous, (2) leaves with ribbed upper surfaces, amphistomatous, (3) leaves with ridged upper surfaces, rolled with drying, epistomatous, and (4) leaves permanently rolled or folded, epistomatous. I was unable to find published comparative data on relative stomatal distributions on grass leaves in relation to rolling or drought resistance that would verify the generalizations described above. Parkhurst (1978) pointed out that the limited data in the literature show no clear trends 1 This research was supported by a Natural Science and Engineering Research Council of Canada grant. Thanks go to G. Shaw who did the electron microscopy work using facilities in the Department of Biology, University of Saskatchewan. V. L. Harms contributed valuable discussion regarding drought resistance classification. 2 Department of Crop Science and Plant Ecology, University of Saskatchewan, Saskatoon S7N OWO, Canada. ANN. MISSOURI BOT. GARD. 72: 833-842. 1985. This content downloaded from 207.46.13.153 on Fri, 05 Aug 2016 06:11:51 UTC All use subject to http://about.jstor.org/terms

Aims Morphological variation of leaves is a key indicator of plant response to climatic change. Leaf size and shape are associated with carbon, water and energy exchange of plants with their environment. However, whether and how leaf size and shape responded to climate change over the past decades remains poorly studied. Moreover, many studies have only explored inter- but not intraspecific variation in leaf size and shape across space and time. Methods We collected >6000 herbarium specimens spanning 98 years (1910–2008) in China for seven representative dicot species and measured their leaf length and width. We explored geographical patterns and temporal trends in leaf size (i.e. leaf length, leaf width and length × width product) and shape (i.e. length/width ratio), and investigated the effects of changes in precipitation and temperature over time and space on the variation in leaf size and shape. Important Findings After accounting for the effects of sampling time, leaf size decreased with latitude for all species combined, but the relationship varied among species. Leaf size and shape were positively correlated with temperature and precipitation across space. After accounting for the effects of sampling locations, leaf size of all species combined increased with time. Leaf size changes over time were mostly positively correlated with precipitation, whereas leaf shape changes were mostly correlated with temperature. Overall, our results indicate significant spatial and temporal intraspecific variation in leaf size and shape in response to climate. Our study also demonstrates that herbarium specimens collected over a considerable period of time provide a good resource to study the impacts of climate change on plant morphological traits.

The effect of channel maintenance on the aquatic macrophytes of the drainage channels of the monmouthshire levels, South Wales, 1840–1976

The article presents results of the study of flora of the reservoirs in the eastern part of the Dnieper-Donetsk basin. An annotated list of flora was compiled on the base of personal field research, analysis of herbarium materials, and available literature data. The annotated list provides information on the herbarium specimens, species distribution in the study region, its general geographic distribution, habitat ecology, conservation status, life form, economic significance, and known literature references in the study region. It is established that the flora of water bodies of the area in question includes at least 61 species of higher aquatic vascular plants. The family Potamogetonaceae is the most species-rich (18 species, about 30% of the total aquatic flora of the region). The most species-rich genus is Potamogeton (16 species); other taxa are represented by a small number of species. A dominant life form is a group of submerged rooted aerohydatophytes, which numbers 28 species (45.9% of the total flora); the rooted aerohydatophytes with leaves floating on the water surface account for 12 species (19.6%). In terms of geographical distribution, the most abundant is the species group with a circumpolar type of area (28 species). Fourteen species have Eurasian ranges. Other area types are represented by a small number of species. The aquatic flora of the eastern part of the Dnieper-Donetsk basin has a high sozological value. Twenty-six species (42.6% of the flora) have conservation status. The Red Book of Ukraine includes six species, viz. Aldrovanda vesiculosa L., Utricularia intermedia Hayne, U. minor L., Salvinia natans (L.) All., Trapa natans L., and Nymphoides peltate (S.G. Gmel.) Kuntze. Three of them are listed in Annex I of the Berne Convention, and the other three are tertiary relics. Three species are included in the European Red List of Vascular Plants. The list of rare, endangered, typical, and in need of special protection plant groups (Green Book…., 2009) includes 14 aquatic assemblages. Recently, against the background of a general decrease in autochthonous floristic diversity, new invasive species have appeared in the region, behaving aggressively towards the native flora: Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms.

High methylmercury uptake by green algae in Lake Titicaca: Potential implications for remediation

An ecosystem is generally sustained by a set of integrated physical elements forming a functional landscape unit—ecotope, which supplies nutrients, microclimate, and exchanges matter and energy with the wider environment. To better predict environmental change effects on ecosystems, particularly in critically sensitive regions such as high altitudes, it is imperative to recognise how their natural landscape heterogeneity works at different scales to shape habitats and sustain biotic communities prior to major changes. We conducted a comprehensive survey of catchment physical, geological and ecological properties of 380 high-altitude lakes and ponds in the axial Pyrenees at a variety of scales, to formulate and test an integrated model encompassing major flows and interactions that drive lake ecosystems. Three composite drivers encompassed most of the variability in lake catchment characteristics. In order of total percentage of variance explained, they were (i) hydrology/hydrodynamics—responsible for type and discharge of inlets/outlets, and for waterbody size; (ii) bedrock geomorphology, summarising geology, slope and fractal order—all dictating vegetation cover of catchment slope and lake shore, and the presence of aquatic vegetation; and (iii) topography, that is, catchment formation type—driving lakes connectivity, and the presence of summer snow deposits. Although driver (i) appeared to be local, (ii) and (iii) showed gradient changes along altitude and latitude. These three drivers differentiated several lake ecotopes based on their landscape similarities. The three-driver model was successfully tested on a riparian vegetation composition dataset, further illustrating the validity and fundamental nature of the concept. The findings inform on the relative contribution of scale-dependent catchment physical elements to lake ecotope and ecosystem formation in high-altitude lakes, which should be considered in any assessment of potentially major deleterious effects due to environmental/climate change.

Changes of organic matter sources in sediment cores from a high-altitude lake (Pumoyum Co, southeastern Tibetan plateau) over the last 19,000 years