Lakeshore Plants Research Articles

Effects of water level fluctuations on lakeshore vegetation of three subtropical floodplain lakes, China

Vegetation communities in floodplain lakes are adapted to natural water regimes. Construction of sluices or dams between rivers and their floodplain lakes will inevitably lead to great changes in plant communities. In order to evaluate the effects of water level fluctuations (WLFs) on lakeshore vegetation in floodplain lakes of the Yangtze River, a field investigation was conducted in two river-disconnected lakes (Wuchang Lake and Shengjin Lake) and one river-connected lake (Shimen Lake). The results showed that plant species richness was highest in the disconnected Shengjin Lake with intermediate amplitude of WLFs, and lowest in the connected Shimen Lake. Species composition differed among the three lakes and the two disconnected lakes with more similar WLFs exhibiting the greatest similarity. Six plant communities were classified using TWINSPAN. Multivariate analyses showed that the amplitude of WLFs was the most important factor in determining the distribution of lakeshore plants, followed by relative elevation and duration of submergence. Our results provide an eco-hydrological basis for plant restoration in the Yangtze floodplain lakes. We suggest that fluctuating amplitude should be increased in lakes with small WLFs, and small habitats with various hydrological regimes should be created in lakes with large WLFs.

滇西北高原纳帕海湿地湖滨带优势植物生物量及其凋落物分解

选取滇西北高原湿地纳帕海湖滨带优势植物茭草(<em>Zizania caducifolia</em>)、水葱(<em>Scirpus tabernaemontani</em>)和刘氏荸荠(<em>Heleocharis liouana</em>),研究其生物量及其凋落物分解特征,结果表明:水葱、茭草、刘氏荸荠为纳帕海湿地湖滨带单优植物群落,均具有较高的地上生物量,不同植物群落地上生物量不同,其中,茭草地上生物量(853.6±58.2)g·m^-2·a^-1显著高于水葱(730.7±7.8)g·m^-2·a^-1与刘氏荸荠(338.9±32.6) g·m^-2·a^-1的地上生物量。3种植物群落凋落物分解速率不同、并随月平均气温升高均呈增加的趋势,其中,刘氏荸荠分解速率<em>k</em>值最大(0.067±0.0026)、茭草(0.062±0.0072)其次、水葱最小(0.039±0.0062)。凋落物经过1年的分解,水葱、茭草和刘氏荸荠凋落物存留率分别为(62.0±8.8)%、(47.5±9.0)%和(44.5±7.9)%。综合3种湖滨带植物地上生物量与凋落物年分解,水葱地上生物量年存留量(453.1±4.9) g·m^-2·a^-1显著高于茭草(405.4±27.7) g·m^-2·a^-1和刘氏荸荠(150.9±14.5) g·m^-2·a^-1。研究进一步表明滇西北高原湿地湖滨带植物具有极高的生物量存留率,成为该类型湿地生态系统碳汇功能的基础,其碳汇过程及其贡献率需要进一步深入研究。;Biomass production and litter decomposition of wetland plants are two important phases for carbon cycle of wetland ecosystems and its trade-off is essential for the carbon sink function and carbon sequestration research on wetland ecosystems. Napahai wetland, one of the 12 Ramsar plateau wetlands, is located in the northwest Yunnan plateau. It is a typical wetland with enclosed and semi-enclosed character and its high biodiversity and uniqueness has received considerable concern worldwide. However, there is few studies on its ecological function of regional carbon cycle and greenhouse gas trade-off under a chilly and humid plateau climate. In this paper, three dominant lakeshore plants, <em>Zizania caducifolia, Scirpus tabernaemontani</em> and <em>Heleocharis liouana</em> were selected as target species. For each species their community characteristics and aboveground biomass were measured by field survey and harvesting, and their litter decomposition rate was determined by mesh bag method. The aims of this study were 1) to quantify biomass retention among these species and 2) to gain insights into the carbon cycle process of wetland ecosystems and their roles of different lakeshore plants. The results showed that <em>Zizania caducifolia, Scirpus tabernaemontani,</em> and <em>Heleocharis liouana</em> all formed typical lakeshore monoculture communities with high biomass that varied among species. Aboveground biomass of <em>Zizania caducifolia</em> (853.6±58.2) g·m^-2·a^-1 was significantly higher than those of <em>Scirpus tabernaemontani</em> (730.7±7.8) g·m^-2·a^-1, and <em>Heleocharis liouana</em> (338.9±32.6) g·m^-2·a^-1. In addition of a general trend of increase with rising mean monthly temperatures, their litter decomposition rates differed. The decomposition rate value <em>k</em> of <em>Heleocharis liouana</em> (0.067±0.0026) was the largest, followed by <em>Zizania caducifolia</em> (0.062±0.0072) and <em>Scirpus tabernaemontani</em> (0.039±0.0062). Meanwhile, after one-year decomposition, the litter residual was (62.0±8.8)%, (47.5±9.0)% and (44.5±7.9)% for <em>Scirpus tabernaemontani</em>, <em>Zizania caducifolia and Heleocharis liouana</em> respectively. Further analysis showed that the annual retention of aboveground biomass of <em>Scirpus tabernaemontani</em> (453.1±4.9) g·m^-2·a^-1 was significantly higher than those of <em>Zizania caducifolia</em> (405.4±27.7) g·m^-2·a^-1 and <em>Heleocharis liouana</em> (150.9±14.5) g·m^-2·a^-1. These results indicated that litter decomposition rate of the lakeshore plants were low under the chilly and humid condition of Napahai wetland. Consequently a large amount of biomass of lakeshore plants could be accumulated into the soil in the form of organic matter, which served as a carbon sink function in such ecosystem. This study obtained a primary picture on carbon sink function and carbon sink process in Napahai wetland in the northwestern Yunnan Plateau and further study on plant-specific processes and their roles is needed to reveal the carbon sequestration processes and functions in this region.

Quantitative evaluation of water-level effects on “regeneration safe-sites” for lakeshore plants in Lake Kasumigaura, Japan

Nishihiro, J. and I. Washitani. 2009. Quantitative evaluation of water-level effects on “regeneration safe-sites” for lakeshore plants in Lake Kasumigaura, Japan. Lake Reserv. Manage. 25:217–223. We evaluated the effects of water-level regime on the area of “regeneration safe-sites” for seed germination and initial establishment of seedlings of helophytes occurring in the emergent vegetation zone of Lake Kasumigaura, Japan. Based on the results of previous studies and an original experiment, potential regeneration safe-sites (PRS) for helophytes were defined as sites in which the ground surface was inundated for less than 3 consecutive days from 1 April to 15 May. We estimated and compared the areas of PRS both before and after the implementation of an artificial water-level regime in the mid-1970s. Comparisons were made using data on daily water levels during 1960–1969 and 1996–2005, topographic profiles of the lakeshore in 1967 and 2005, and areas of the emergent vegetation in 1972 and 1997. We estimated that the current area of PRS in the lake has been reduced to 24% of past levels. This reduction was accompanied by both a complete loss of a spring drawdown and a decrease in the area of emergent vegetation. The areas of PRS under various water management regimes indicated that a relatively slight lowering of the spring water level could cause a marked increase in the area of PRS (e.g., a 10-cm decrease in the managed target water level could result in a doubling of the area of PRS). Our results suggest a water-level management policy that includes a spring drawdown can be effective in the restoration of helophyte species diversity through the recovery of PRS.

"Ribbon of Steel and Concrete": A Cultural Biography of the Buffalo Skyway (1955)

The Buffalo Skyway, a mile long and 110 feet high, opened in 1955 in an atmosphere of triumph and celebration, city planners certain that the enormous structure would invigorate the area's economy by eliminating troublesome rail and automobile bottlenecks between the city's downtown core and lakeshore plants and factories to the southwest. Today, the bridge is the whipping boy for politicians and regionalists, who view the structure as a concrete dinosaur, astride waterfront land that might otherwise be productively developed, ala Baltimore. This essay examines the cultural forces that produced the Skyway and many similar structures of the era. It contextualizes Buffalo's high-level bridge not just as an instrument of efficiency and commercial renewal, but as an icon of size and power, speed and mobility, movement and flight--a piece of 'structural art' in the mode of biomorphic, vital forms modernism, built and egineered for those who loved to drive, in the golden age of the American automobile.

Cause of Periodic Variation in Lakeshore Elevation at Ohyama Region in Lake Kasumigaura

Kasuga (2006) has been measuring the lakeshore elevation at a point in front of the seawall at Ohyama region in Lake Kasumigaura once a day since 1993. Due to this observation, the elevation at the point showed a strong periodicity of a year. To investigate the cause of the changes, original data taken by Kasuga was analyzed as well as seabed sounding and sampling test of seabed materials. Wave forecasting and numerical simulation using the contour-line-change model was carried out. It was found that this periodic variation of the elevation was induced by the seasonal changes in direction of longshore sand transport on a pocket beach between a drainage gate and lakeshore plants.

Regeneration failure of lakeshore plants under an artificially altered water regime

To reveal the effects of artificial alteration of water level regime on the regeneration of lakeshore plants from seeds, we examined the factors causing regeneration failure in Lake Kasumigaura, Japan. A survey of microtopography within and around a remnant fragment of lakeshore vegetation revealed that, over a large range, the habitat is frequently inundated in spring under the current water regime, although it was rarely inundated under past water regimes. Analysis of the patterns of seedling emergence and establishment at microsites at various elevations revealed a significant negative correlation between number of inundation days and abundance or species‐richness of seedlings that emerged in the spring. Most seedling deaths occurred when the study site was inundated. We suggest that regeneration failure caused by the artificial raising of the lake's water level is one of the principal mechanisms of the recent vegetational decline in the lake.

Germination characteristics of lakeshore plants under an artificially stabilized water regime

To examine the possibility of the failure of lakeshore plants to germinate under an anthropogenically controlled water regime, we investigated physiological germination responses to temperature and inundation among 25 lakeshore plant species from Lake Kasumigaura, Japan. The requirement of low temperature for dormancy breakage, which is common in spring-germinators, was seen in 14 species. Eight species showed sensitivity to temperature fluctuation, which is thought to be relevant to bare ground detection for germination. Seed germination of most species was significantly reduced under inundation. Seedling emergencies under outdoor conditions in which the wet and inundated conditions of the natural lakeshore habitat were simulated showed that the timing of all species was concentrated in spring. A significant reduction of emergence in the inundated condition was observed in 19 species. Therefore, most of the lakeshore plant species are adapted to germinate in spring on exposed bare ground during low-water periods. The recent imposition of water level control with a winter-spring elevation possibly prevents regeneration of most common lakeshore plants through the loss of seasonal safe sites for germination.

Archaeobotanical investigations of late neolithic lakeshore settlements (Lake Biel, Switzerland)

This paper describes the results of the archaeobotanical examination of four Late Neolithic lakeshore settlements on Lake Biel in Switzerland. Due to the excellent preservation conditions in lakeshore settlements, non-carbonized as well as carbonized seeds and fruits were recovered in large numbers. In addition to the diaspore analyses, some samples of charcoal and moss were identified. The spectrum of cultivated plants was markedly different between the sites. In the transition from the 34th to 33rd century B.C. (sites Nidau, Lüscherz and Lattrigen ‘VI’) naked wheat and barley were predominant, while in the 32nd century B.C. (Lattrigen'VII') emmer (a glume wheat) was most abundant. Flax and opium poppy were of great importance during the whole late Neolithic period. In addition to cereals, a large number of cereal weeds were detected. The wild flora included a high percentage of aquatic and lake-shore plants which results from the strong influence of water on the cultural layers. Taxa of flood-plain forest are also common. The proportion of potential grassland plants was low (in total only 13 taxa) which suggests that in addition to the cultivated fields only few pastures and grassland areas existed close to the settlements.

Plasticity, Morphology and Distribution in Twelve Lakeshore Plants

The ecological significance of plasticity in twelve lakeshore plant species was investigated by examining the relationship of plasticity to growth form, competitive ability and position along an environmental gradient of soil organic matter content. Study species occupied different positions along the gradient and had a variety of growth forms, including basal rosettes, creeping graminoids, and stemmed, leafy dicots. Plasticity was measured in plants grown singly along an experimental gradient of soil organic matter content for one growing season. The degree of platicity exhibited by a species was not significantly related to its competitive ability measured in a diallel experiment

Effects of a water-depth gradient on the germination of lakeshore plants

The germination requirements of many wetland species commonly found in the seed bank are poorly understood. The purpose of this study is to explore the germination responses of lakeshore plant species to a water-depth gradient on each of two soil types normally found on shorelines and to test whether germination patterns predict field distributions of adults. Germination patterns were determined in a greenhouse by sowing seeds of 24 lakeshore species along an artificial water-depth gradient, using two soil types (sand and organic soil). Those species showing significant treatment effects were then tested for similar or different germination patterns, using Kendall's coefficient of concordance. Species had similar germination patterns (n = 5, P = 0.02) on sand. Species had different germination patterns (n = 7, P &gt; 0.50) on the organic soil. Mean water-depth of germination was significantly correlated with the mean depth occupied by adults in the field for seven species (r = 0.81, P = 0.04). This study shows that germination requirements are important in controlling recruitment of wetland species after disturbance.

Biomass accumulation by Rhexia virginica and Triadenum fraseri along two lakeshore gradients: a field experiment

Lakeshore plants are distributed along many gradients, two of which are exposure to waves and water depth (height on the shoreline). Not only does disturbance vary along these gradients, but the rate of recovery after disturbance may vary as well. We therefore tested whether biomass accumulation in two shoreline plants, Triadenum fraseri and Rhexia virginica, was influenced by these two gradients, and whether the responses of the two species differed. The exposure gradient was represented by three substrate types (measured by soil organic content) and the height gradient was represented by three positions relative to the lower limits of shoreline shrubs. The greatest accumulated biomass for both species was found below the lower limits of shrubs in organic substrates. The rate of recovery after disturbance would therefore be lower on sandy shores, even though such shores are more regularly disturbed. Rhexia virginica is normally restricted to substrates with an intermediate organic content, but there is no evidence that it is narrowly specialized upon this substrate as it actually grew better in the organic treatment. Rhexia virginica did not respond to favourable changes in either experimental factor when the other factor was not also favourable to growth. Triadenum fraseri, however, increased in biomass when one of the factors was favourably changed, regardless of the second factor. These differences may partially explain the more restricted distribution of R. virginica on shorelines.