Species Of Wet Habitats Research Articles

Spatial and temporal patterns of species replacement in the Middle Pleistocene: а case study of Мicrotus nivaloides Major, 1902 and morphologically related species of the Northern Black Sea and Azov areas

AbstractThe Middle Pleistocene replacement of the extinct Microtus nivaloides with its likely descendant field vole (M. agrestis Linnaeus, 1761) shows regional differences suggesting the climatic control of the process. Our aim was to test this hypothesis. We studied samples of M. nivaloides and morphologically related species, both recent and extinct, from the Northern Black Sea and Azov areas by means of geometric morphometry. There were measured pairwise Euclidian distances between each fossil specimen and centroids of the extant groups, and between centroids of all studied groups. When the studied samples were arranged in stratigraphic order, the decrease in these distances indicated the nearest approach to (i.e. the appearance of) M. agrestis within the considered area. Our results show that it was an expansion rather than a continuation of previous evolutionary trends. M. agrestis, the species of wet habitats, came to the Northern Black Sea area from the west during the warm and humid Holsteinian interglacial (MIS 11). The species was not widespread within the area and allopatrically coexisted with M. nivaloides. Besides, Holsteinian warming enhanced migration of other mesophilic vole species from adjacent areas. Our approach may be expanded to other extinct species with overlapping ranges of variation.

Changes in subarctic vegetation after one century of land use and climate change

AbstractQuestionsHave species richness and composition in subarctic vegetation changed over the past ca. 90 years? Are compositional shifts linked to changes in land management or climate? Are observed changes associated with vegetation type, life form, or habitat preference?LocationRybachy and Sredny Peninsulas, NW Russia.MethodsWe resurveyed vegetation ca. 90 years after the first sampling in 1927–1930 to study changes in species richness, abundance and composition. Because of missing plot‐related environmental measurements we used a weighted averaging approach calculating relative changes in species‐specific optimum values for different environmental gradients represented by species indicator values to identify compositional change in relation to the environment. Changes in species composition were visualised using detrended correspondence analyses. Significances of observed changes in species richness and frequency were evaluated using restricted permutation tests. A χ2 test was used to test if observed changes in abundances were related to species’ life form and habitat preferences.ResultsSpecies composition has changed significantly over the past ca. 90 years, as indicated by significant changes in species’ frequencies and values of optima for the environmental gradients temperature, moisture, nutrients and light. Species richness decreased significantly, in particular in nitrophilous and wet growing vegetation. Species typical for grazed grasslands and meadows and species of wet habitats became less abundant, while dwarf shrubs and forest species increased.ConclusionsLand abandonment, in combination with climate change, is likely to have caused the observed changes in the subarctic vegetation of NW Russia. Shifts in the species dominance ratios and interspecific competition (e.g. for reallocated nutrients) after land abandonment may have been promoted by the subsequent change towards a warmer climate, facilitating the regrowth of previously open meadows with grazing‐intolerant tall herbs, forest herbs and dwarf shrubs. This study illustrates clearly the long‐term effects of land‐use change, the consequences of which are still visible even after almost one century in the subarctic.

Helianthus porteri, a Granite Outcrop Endemic, Does Not Have More Drought Resistant Traits Than Congeners

AbstractHelianthus porteri, a sunflower endemic to drought prone granite outcrops, has been hypothesized to be drought resistant. We compared H. porteri to three Helianthus species (H. annuus, H. agrestis, H. carnosus) from less drought prone habitats for traits associated with drought avoidance and tolerance in greenhouse experiments. Under well-watered conditions, H. porteri had high specific root length suggestive of high capacity for water uptake, but intermediate root mass ratio (RMR) and shallow rooting inconsistent with enhanced capacity for drought avoidance. In response to mild drought, none of the species exhibited osmotic adjustment, and H. porteri had no change in RMR and no greater capacity to increase water-use efficiency, again, inconsistent with greater drought avoidance. In response to cessation of watering, H. porteri wilted at a leaf water potential similar to a wet habitat species, inconsistent with greater drought tolerance. Overall, under the conditions assessed, we found no evidence that H. porteri possesses traits that confer a unique ability to avoid or tolerate drought as compared to congeners.

Water availability, fundamental niches and realized niches: A case study from the Cape flora

AbstractThe ability of plants to survive drought or waterlogging constitutes an important niche parameter, which might be particularly significant in explaining species coexistence in the species‐rich and seasonally dry Cape Floristic Region of South Africa. However, the degree of physiological adaptation and specialization to these eco‐hydrological parameters (the fundamental niche) cannot be readily inferred from correlative studies based on species distributions and spatial variation in environmental parameters (the realized niche). We used an ex situ greenhouse experiment to compare the fundamental hydrological niches (different mean annual precipitation, rainfall seasonality and soil drainage) of six eco‐hydrologically divergent African Restionaceae species. Juvenile plants were subjected to six different watering treatments, ranging from no watering to waterlogging, to determine drought and waterlogging susceptibility and optimal growth conditions. We used the rate of biomass accumulation and survival rate as response measures. We found that species from dry and mesic (but well‐drained) habitats had optimal or near‐optimal growth at benign conditions (under which most restio species grow well). All species performed worse when droughted and died when not watered. Species from dry habitats tended to perform better (assessed in growth) than species from wet habitats under droughting. Species from wet habitats performed best when waterlogged, whereas species from dry habitats performed very poorly when waterlogged – thus showing that realized and fundamental niches covaried at the wet end of the hydrological gradient. We conclude that eco‐hydrological parameters are part of the fundamental niche, and fundamental and realized species niches are approximately correlated along them. The distribution of wet habitat species appears not to reflect their drought tolerance, suggesting that it may not be predicted by bioclimatic variables, but rather by soil drainage characteristics.

Reproductive Strategies and Life History Evolution of Some CaliforniaSpeyeria(Nymphalidae)

ABSTRACT. Egg weights and total eggs produced by nine Speyeria spp. (Nymphalidae) in California allowed estimates of per-egg and lifetime reproductive effort. Interpopulation reproductive effort in four species and intrapopulation reproductive effort of two species in different years were documented. Female body weight was uncorrelated with either individual egg weight or total lifetime egg weight. Smallest eggs (mean dry wt/egg = 0.05 – 0.06 ug), and the greatest number of eggs, were from S. coronis (Skinner) and S. zerene (Boisduval) whose females undergo summer reproductive diapause in dry habitats. Largest eggs (mean dry wt/egg = 0.10 ug) were from S. nokomis (Skinner), a wet habitat species. The greatest relative reproductive effort was made by dry habitat species lacking reproductive diapause. Reproductive effort and duration of first instar exposure to summer temperatures were positively correlated. Intrayear variation in total egg weight did not vary significantly among populations of S. callippe ...

Morphological and physiological differentiation of seedlings between dry and wet habitats in a tropical dry forest

A common observation in tropical dry forests is the habitat preference of tree species along spatial soil water gradients. This pattern of habitat partitioning might be a result of species differentiation in their strategy for using water, along with competing functions such as maximizing water exploitation and tolerating soil water stress. We tested whether species from drier soil conditions exhibited a tolerance strategy compared with that of wet-habitat species. In a comparison of 12 morphophysiological traits in seedlings of 10 closely related dry and wet-habitat species pairs, we explored what trade-offs guide differentiation between habitats and species. Contrary to our expectations, dry-habitat species showed mostly traits associated with an exploitation strategy (higher carbon assimilation capacity, specific leaf area and leaf-specific conductivity and lower water-use efficiency). Strikingly, dry-habitat species tended to retain their leaves longer during drought. Additionally, we detected multiple strategies to live within each habitat, in part due to variation of strategies among lineages, as well as functional differentiation along the water storage capacity-stem density (xylem safety) trade-off. Our results suggest that fundamental trade-offs guide functional niche differentiation among tree species expressed both within and between soil water habitats in a tropical dry forest.

Ecophysiological responses of nine floodplain meadow species to changing hydrological conditions

Here, we investigated how species from different floodplain meadow plant communities differ in their ecophysiological responses to an abrupt change in hydrological conditions. We simulated two contrasting hydrological scenarios for 5 weeks under controlled conditions: the waterlogging of a mesophilic species mixture (flooding scenario) and the drying of a hygrophilic species mixture (drying scenario). The mesophilic mixture was composed of three characteristic species of dry habitats (dry species) and three indifferent species with regard to the hydrological conditions; the hygrophilic mixture was composed of three characteristic species of wet habitats (wet species) and the same three indifferent species. The flooding scenario induced a significant decrease in photochemical efficiency (F v/F m) of all species for at least one day, and four of these species did not readjust their F v/F m at the end of the experiment. The F v/F m of four species was significantly reduced by the drying scenario, but was readjusted within the time of the experiment. Significant leaf plastic responses were mainly detected under the drying scenario, through increasing specific leaf area (SLA) and decreasing leaf dry matter content (LDMC) for two indifferent species, and through decreasing SLA and increasing LDMC for two wet species. Finally, the flooding scenario significantly decreased the aboveground biomass of one dry species, but increased the aboveground biomass of the three indifferent species, suggesting an acclimation response to waterlogging through increasing shoot/root ratio. Since the dry species did not show ecophysiological acclimation to changing hydrological conditions (in contrast to the wet species and the indifferent species), this study demonstrated that mesophilic meadow communities should be particularly affected by a change from dry to wet conditions.

Effects of Light, Scarification, and Gibberellic Acid on Seed Germination of Eight Pedicularis Species from Yunnan, China

Seeds of most Pedicularis species do not germinate easily and uniformly, which hinders the process of seeking solutions for successful cultivation of these taxa. In an attempt to determine optimal conditions and effective methods for uniform, rapid, and high-percent germination, the effects of light, scarification, and gibberellic acid (GA3) were tested on seed germination of eight Pedicularis species from nine sites in the northwestern Yunnan Province of China. There were some differences in germination characteristics among the tested species. Seed germination of some species was promoted by light, but not in others. Wet-habitat species generally had positive photoblastic responses. For many species, scarification was effective to promote seed germination, but neither 100 nor 500 mg·L−1 GA3 had consistent promoting effects.

Genome size variation in Central European species of Cirsium (Compositae) and their natural hybrids.

Nuclear DNA amounts of 12 diploid and one tetraploid taxa and 12 natural interspecific hybrids of Cirsium from 102 populations in the Czech Republic, Austria, Slovakia and Hungary were estimated. DAPI and PI flow cytometry were used. 2C-values of diploid (2n = 34) species varied from 2.14 pg in C. heterophyllum to 3.60 pg in C. eriophorum (1.68-fold difference); the 2C value for the tetraploid C. vulgare was estimated at 5.54 pg. The DNA contents of hybrids were located between the values of their putative parents, although usually closer to the species with the smaller genome. Biennial species of Cirsium possessed larger nuclear DNA amounts than their perennial relatives. Genome size was negatively correlated with Ellenberg's indicator values for continentality and moisture and with eastern limits of distribution. A negative relationship was also detected between the genome size and the tendency to form natural interspecific hybrids. On the contrary, C-values positively corresponded with the spinyness (degree of spinosity). AT frequency ranged from 48.38 % in C. eriophorum to 51.75 % in C. arvense. Significant intraspecific DNA content variation in DAPI sessions was detected in C. acaule (probably due to the presence of B-chromosomes), and in tetraploid C. vulgare. Only the diploid level was confirmed for the Pannonian C. brachycephalum, generally considered to be tetraploid. In addition, triploidy was discovered for the first time in C. rivulare. Considerable differences in nuclear DNA content exist among Central European species of Cirsium on the diploid level. Perennial soft spiny Cirsium species of wet habitats and continental distributions generally have smaller genomes. The hybrids of diploid species remain diploid, and their DNA content is smaller than the mean of the parents. Species with smaller genomes produce interspecific hybrids more frequently.

Comparing weed composition in natural and planted hedgerows and in herbaceous field margins adjacent to crop fields

Hedgerows and field margins are common features of the agricultural landscape in southern Québec. In the last decade, hedgerow establishment has been encouraged primarily for the prevention of soil erosion, though many farmers view them as reservoirs of invasive weeds and pests. In this study, we compared weed assemblages of several hedgerow types and herbaceous field margins. Ranking that takes into consideration weed abundance was clearly demonstrated: planted hedgerows > herbaceous field margins > natural woody hedgerows. The latter harboured many perennial plant species of less weedy propensity than planted hedgerows, which accommodated a larger number of weedy species. In planted hedgerows close to 50% of plants were weeds, even in their central position, although planted and natural hedgerows sheltered similar weed composition in their central parts. Likewise, most species inventoried in adjacent fields were weeds. Weeds characterising the central position of hedgerows/field margins were often species of wet habitats (Lythrum salicaria L., Equisetum arvense L., Cicuta maculata L.). Management practices of hedgerows and perhaps of crop fields adjacent to hedgerows may be mostly responsible for the abundance of weeds in hedgerows and field margins. Key words: Hedgerow, field margins, weed, management practices, pesticide, fertiliser

ITS Base Sequence Phylogeny in Bidens (Asteraceae): Evidence for the Continental Relatives of Hawaiian and Marquesan Bidens

Abstract We sequenced the complete ITS regions and the 5.8S gene of nuclear ribosomal DNA of 24 plants representing 20 species and two hybrids from six sections of Bidens, plus one species of Cosmos, and produced a phylogenetic tree. All Hawaiian species have identical sequences, including B. cosmoides. Bidens cosmoides is the most morphologically divergent species in the genus, and has previously been segregated into the monotypic section Degeneria and considered to represent a separate introduction of Bidens into Hawaii. Hawaiian and southeast Polynesian species represent a single monophyletic colonization of islands in the Pacific Ocean. There is a basal dichotomy in Bidens between north temperate species of wet habitats in sections Hydrocarpaea and Bidens and subtropical and tropical species of well drained habitats in sections Psilocarpaea, Campylotheca, and Greenmania, suggesting the two groups are not closely related. Segregation of the aquatic B. beckii as the monotypic genus Megalodonta is not su...

Reductions in abscisic acid are linked with viviparous reproduction in mangroves

We investigate physiological mechanisms behind the convergent evolutionary loss of seed dormancy in plant lineages, focusing on mangroves as a model system. More than 60 angiosperm families, including several mangrove taxa, contain species with seeds that are intolerant of drying and do not undergo dormancy. These desiccation-intolerant species occur with disproportionate frequency in wet or coastal tropical habitats. In plants, the hormone abscisic acid (ABA) coordinates both the development of desiccation tolerance during the onset of seed dormancy and whole-organism responses to flooding. Thus, changes in ABA levels and/or modes of action in different plant compartments are implicated in the repeated evolutionary loss of seed dormancy among species of wet habitats. We compare ontogenetic dynamics of ABA levels in embryonic, maternal, and mature vegetative tissue of four phylogenetically independent pairs of related viviparous mangroves and nonviviparous nonmangroves. We demonstrate that ABA levels are consistently lower in embryos of viviparous mangrove taxa than embryos of nonmangrove, nonviviparous sister taxa. In contrast, elevated tissue concentrations of ABA characterize leaves of all mangrove species tested, while ABA levels in maternal tissues vary among mangrove species. These commonalities suggest a functionally important trade-off between the maintenance of embryonic development and the adjustment of the parent tree to salinity stress. This study yields comparative data on seed physiology in naturally occurring desiccation-intolerant species, for which these data are currently scarce, and demonstrates a potentially significant role of phytohormones in the evolution of plant life histories.

Distribution and conservation status of littoral vascular plant species along the European coasts

A comprehensive list of 1068 typical littoral plant species and subspecies has been composed. They are considered endemic in a wide sense and are subdivided into widespread, transregional, regional and local endemics, the latter three categories being considered as endemics s.s. For each taxon the distribution, habitat preference, endemic status and conservation status are given. The list, which is available upon request, is summarized in a number of figures and tables, from which it appears that 61% of all species are endemics s.s., that ca. 30% of all species are dune and beach species and another nearly 30% are maritime rock species. Species of wet habitats are concentrated in northern and northwestern Europe, dune species in western and southwestern Europe, western Mediterranean and Black Sea. The conservation status of most species is indicated; 37% is considered threatened. It is concluded that the Bern Convention and the European Habitat Directive offer an entirely insufficient framework for effective conservation action. It is suggested to take the present list as a starting point for a geographical/taxonomical/ecological data base of European coastal endemics.

Some Effects of Afforestation on the Flora and Fauna of an Upland Sheepwalk During 12 Years After Planting

(1) Following afforestation of an upland sheepwalk, the effects of reduced grazing, ground preparation and the early stages of plantation development induce marked changes in the frequency of occurrence of vascular plants and of vertebrate animals. (2) On an area of 139 ha, the number of vascular plants recorded in systematically placed quadrats changed little in the first 9 years: eighty-one remained whilst twenty-seven disappeared and were replaced by twenty-nine others. Quadrats placed in Sitka spruce and western hemlock plantations had significantly fewer plant species after 9 years. Grasses and rushes increased most in frequency whilst species of wet habitats and of small stature became less frequent. (3) An estimated 271 pairs of birds, of twenty species, nested on the study area in 1972, but in 1984, 724 pairs from twenty-five species nested, of which only seven species remained from 1972. (4) Tests of association between selected feeding or breeding birds and mammals and site characteristics suggested significant positive and negative associations with vegetation, tree species, tree height and woodland edge. Bird densities showed large variations within the study area, particularly in relation to tree height, and whilst whinchat densities were less than reported elsewhere, coal tits and goldcrests were present in greater densities. A flight pond provided good bags of duck for at least 8 years.

The Flammability and Energy Content of Some Important Plant Species and Fuel Components in the Forests of Southeastern Tasmania

Energy content and rate of flame front movement in various plant species and fuel components from the forests of southeastern Tasmania exhibited a range in values, and responses. Eucalypt dry forest species and fuel components showed the highest energy content and the greatest tendency to propagate fire whereas species from wet sclerophyll and gully habitats and Casuarina dry forest communities propagated fire less readily. Species from dry habitats have, in general, low ash contents, high energy levels, high volatile oil contents and low moisture contents. Wet habitat species have high percentages of moisture and ash. General support is given to the hypothesis that natural selection has favoured flammable characteristics in fire-dependent plant communities.

The carabid communities on peat and upland grasslands in northern England

During a two year period 13498 individuals of 66 species of carabids were taken from 44 sites on peat and upland grasslands over an altitude range of 11‐847 m in the north of England. The similarities between the carabid faunas of each site have been assessed using a modified form of the Sørensen's Index and the sites clustered according to their similarities. Five carabid communities on peat and three on mineral soils have been identified and the more abundant species have been used to characterise them. Peat Community I occurs on dry heath and is characterised by peat associated species such as Trichocellus cognatus and Bradycellus ruficollis together with widespread open habitat species such as Pterostichus madidus, Notiophilus aquaticus, Calathus melanocephalus and Nebria salina. Peat Community II is found on areas where dry heath and deep wet peat are adjacent and is characterised by the species already mentioned together with typical wet habitat species such as Pterostichus diligens, P. nigrita, Patrobus assimilis. Agonum fuliginosum. Peat Community III is found on blanket bog and is characterised by the wet habitat species in the absence of the species present on the dry heath. Peat Community IV found on the lowland oligotrophic mires is characterised by the small number of species present and the addition of Pterostichus niger and Agonum ericeti to the few wet habitat species present. Peat Community V, on the scarp slope of Dun Fell, consists of the wet habitat species of Peat Community III together with Pterostichus madidus. Nebria salina, Notiophilus aquaticus and Calathus melanocephalus.Grassland Community I, on the fell tops, is characterised by the presence of Nebria gyllenhali, Notiophilus germinyi and Patrobus assimitis. Grassland Community II and III are less clearly defined but Grassland Community II may be present on wetter sites than III and is characterised by the presence of Pterostichus nigrita, P. diligens and P. strennus together with Notiophilus biguttatus. N. aquaticus, Pterosfichus madidus and Patrobus afrorufus. Grassland Community III consists of the latter group of species together with Nebria salina, Calathus melanocephalus and Notiophilus aestuans. The number of grassland sites studied was small and there may be further communities on the upland grasslands.

Carbon dioxide exchange characteristics of C4 Hawaiian Euphorbia species native to diverse habitats.

The characteristics of the photosynthetic apparatus of 11 Hawaiian Euphorbia species, all of which possess C4 photosynthesis but range from arid habitat, drought-deciduous shrubs to mesic or wet forest evergreen trees and shrubs, were investigated under uniform greenhouse conditions. Nine species exhibited CO2 response curves typical of C4 plants, but differed markedly in photosynthetic capacity. Light-saturated CO2 uptake rates ranged from 48 to 52 μmol m-2 s-1 in arid habitat species to 18 to 20 μmol m-2 s-1 in mesic and wet forest species. Two possessed unusual CO2 response curves in which photosynthesis was not saturated above intercellular CO2 pressures [p(CO2)] of 10 to 15 Pa, as typically occurs in C4 plants.Both leaf (g'1) and mesophyll (g'm) conductances to CO2 varied widely between species. At an atmospheric p(CO2) of 32 Pa, g'1 regulated intercellular p(CO2) at 12-15 Pa in most species, which supported nearly maximum CO2 uptake rates, but did not result in excessive transpiration. Intercellular p(CO2) was higher in the two species with unusual CO2 response curves. This was especially apparent in E. remyi, which is native to a bog habitat. The regulation of g'1 and intercellular p(CO2) yielded high photosynthetic water use efficiencies (P/E) in the species with typical CO2 response curves, whereas P/E was much lower in E. remyi.Photosynthetic capacity was closely related to leaf nitrogen content, whereas correlations with leaf morphological characteristics and leaf cell surface area were not significant. Thus, differences in photosynthetic capacity may be determined primarily by investment in the biochemical components of the photosynthetic apparatus rather than by differences in diffusion limitations. The lower photosynthetic capacities in the wet habitat species may reflect the lower light availability. However, other factors, such as reduced nutrient availability, may also be important.

Size, productivity, and paleoecological implications of ericaceous pollen from Burns Bog, southern Fraser River Delta, British Columbia

Measurements of pollen tetrad diameters of eight ericad species from Burns Bog, Delta, B.C., showed that although diameters range continuously from 22 to 53 μm, groups of species can be recognized. These groups are ecologically significant with (i) small tetrads indicating dry habitats, (ii) intermediate tetrads indicating intermediate to dry sites, and (iii) large tetrads characteristic of wet habitat species. Pollen productivity of six of the above species varies, with those in dry sites producing much more pollen than species of wet habitats. Tetrad diameter spectra obtained from bog sediments under various ericad associations are dominated by tetrads of a diameter characteristically produced by the species growing at the site. Therefore fossil ericad assemblages can be interpreted on the basis of tetrad diameters.

Differential effects of water stress on respiration in the light in woody plants from wet and dry habitats

Respiration in the light, dark respiration, and leaf water status were monitored once a day in leaves of woody plants as seedlings dried during 7- to 10-day periods. Light respiration was estimated from an electrical analogue model of the response of net photosynthesis to ambient CO2 concentration and also by the rate of CO2 evolution into CO2-free air. Respiration in the light was found to increase with water stress in four dry-habitat species and to decrease with stress in four wet-habitat species. Dark respiration changes could not account for the different trends observed. When light respiration in dry-habitat plants under water stress was temporarily inhibited, net photosynthesis during recovery from water stress was reduced compared with controls for at least a week. This may indicate a protective role of light respiration in these plants when under water stress.