Average Annual Biomass Research Articles

Testing the importance of native plants in facilitation the restoration of coastal plant communities dominated by exotics

Casuarina equisetifolia was introduced to China in 1897 from Australia to reduce coastal erosion. It grows vigorously and has spread over much of the southern and southeastern coast, from Zhejiang to Guangxi, over a range of more than 10° of latitude. To date, little is known about its interactions with native species in the coastal zone.We used a field experiment to study how the understorey species diversity and soil conditions in monoculture stands of C. equisetifolia were influenced by different native plant species. We also examined the effects of interplanting native species on plant numbers, leaf area index (LAI), and aboveground biomass accumulation. We planted three native species (Hibiscus tiliaceus, Melia azedarach and Calophyllum inophyllum) at two initial densities in stands of C. equisetifolia.Over a period of ten years, the density and aboveground biomass were relatively low in plots planted with three native species compared to plots that were not planted. In contrast, understory diversity and soil conditions were relatively high where native species were added. Moreover, the number of dead tree, aboveground biomass increment, and diameter growth had significant difference among different native tree species because of their different natural characteristics.The fast-growing pioneer species, M. azedarach, had a positive effect on LAI, regeneration, shrub diversity and grass coverage than the other two native species, and M. azedarach was most effective in plots that were initially planted with higher densities. The pioneer plant H. tiliaceus had more individuals and greater aboveground biomass than others native species. The later-succession species C. inophyllum had the smallest effect on the development of understory vegetation and soil conditions over 10-yrs among three native plants. For different native planted species, M. azedarach showed good effects on the average annual aboveground biomass and DBH increment, and C. inophyllum had the least dead number in coastal environments.In summary, C. equisetifolia and native species have facilitation relationships that differ according to the species, and coastal conservation managers should shift from their traditional focus on C. equisetifolia afforestation to the recognition of multi-species configuration.

Remote Sensing-Based Biomass Estimation and Its Spatio-Temporal Variations in Temperate Grassland, Northern China

Grassland biomass is essential for maintaining grassland ecosystems. Moreover, biomass is an important characteristic of grassland. In this study, we combined field sampling with remote sensing data and calculated five vegetation indices (VIs). Using this combined information, we quantified a remote sensing estimation model and estimated biomass in a temperate grassland of northern China. We also explored the dynamic spatio-temporal variation of biomass from 2006 to 2012. Our results indicated that all VIs investigated in the study were strongly correlated with biomass (α < 0.01). The precision of the model for estimating biomass based on ground data and remote sensing was greater than 73%. Additionally, the results of our analysis indicated that the annual average biomass was 11.86 million tons and that the average yield was 604.5 kg/ha. The distribution of biomass exhibited substantial spatial heterogeneity, and the biomass decreased from the eastern portion of the study area to the western portion. The interannual biomass exhibited strong fluctuations during 2006–2012, with a coefficient of variation of 26.95%. The coefficient of variation of biomass differed among the grassland types. The highest coefficient of variation was found for the desert steppe, followed by the typical steppe and the meadow steppe.

Key parameters for outdoor biomass production of Scenedesmus obliquus in solar tracked photobioreactors

The biomass productivity of Scenedesmus obliquus was investigated outdoors during all seasons in solar tracked flat panel photobioreactors (PBR) to evaluate key parameters for process optimization. CO2 was supplied by flue gas from an attached combined block heat and power plant. Waste heat from the power plant was used to heat the culture during winter. The parameters pH, CO2, and inorganic salt concentrations were automatically adjusted to nonlimiting levels. The optimum biomass concentration increased directly with the photosynthetic active radiation (PAR) from 3 to 5 g dry weight (DW) L−1 for a low PAR of 10 mol photons m−2 day−1 and high PAR of 40–60 mol photons m−2 day−1, respectively. The annual average biomass yield (photosynthetic efficiency) was 0.4 ± 0.5 g DW mol−1 photons. However, biomass yields of 1.5 g DW mol−1 photons close to the theoretical maximum were obtained at low PAR. The productivity (including the night biomass losses) ranged during all seasons from −5 up to 30 g DW m−2 day−1 with a mean productivity of 9 ± 7 g DW m−2 day−1. Low night temperatures of the culture medium and elevated day temperatures to the species-specific optimum increased the productivity. Thus, continuous regulation of the biomass concentration and the culture temperature with regard to the fluctuating weather conditions is essential for process optimization of outdoor microalgal production systems in temperate climates.

滴水湖浮游动物群落结构及其与环境因子的关系

PDF HTML阅读 XML下载 导出引用 引用提醒 滴水湖浮游动物群落结构及其与环境因子的关系 DOI: 10.5846/stxb201303010332 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: Zooplankton community structure and its relationship with environmental factors in Dishui Lake Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为研究上海市滴水湖浮游动物群落结构及其与环境因子的关系,于2012年1-12月对滴水湖进行了一年调查采样。共检出浮游动物33属61种,其中轮虫22属45种,枝角类4属7种,桡足类7属9种。优势种包括10种轮虫,桡足类为中华窄腹剑水蚤(Limnoithona sinensis)和无节幼体,枝角类不形成优势种。浮游动物年均密度为1200个/L,年均生物量为1.67mg/L,种类数、密度和生物量均为春夏两季相对较高。Shannon-Wiener多样性指数H'和Margalef丰富度指数D年均值分别为1.61和1.01,多样性季节差异显著而各样点间差异不显著。相关性分析和多元回归分析显示,水温是影响滴水湖浮游动物群落结构变化的决定性因子,冗余分析(RDA)显示TN、TP、叶绿素a和pH也是影响浮游动物群落变化的重要因素,表明滴水湖浮游动物群落结构的季节变化与水体营养状况密切相关。综合运用水质理化因子、综合营养状态指数、多样性指数及浮游动物优势种对滴水湖进行水质污染水平和富营养化评价,得出2012年滴水湖水质状况属于α-中污型,营养程度为中富营养水平。 Abstract:Dishui Lake is the largest artificial lake in Shanghai, China. Water in the lake comes from the Huangpu River via the Dazhi River through surrounding river networks, accepts surface runoff and passes through a sluice into the East China Sea. The lake is important for flood control, drainage, water replacement and other functions, and is critical to the Lin'gang New District's landscape and to Shanghai's eco-city construction. It is a newly formed lake with a fragile ecosystem and could easily be affected by external pollutant sources. Zooplankton play an important role in lake ecosystems and biological productivity at the base of the food chain since they eat phytoplankton, bacteria and detritus and provide food for fish and other aquatic organisms. Filter-feeding fish were put into the lake in recent years to control phytoplankton numbers, but a growing filter-feeding fish population could harm the zooplankton community. Consequently, long-term monitoring of variation in the zooplankton community is vital to the health of Dishui Lake. In order to explore the relationship between zooplankton community structure and environmental factors in Dishui Lake, we investigated the species composition, density and biomass distribution, dominant species of zooplankton and water quality parameters in Dishui Lake. We used eight sampling sites and took samples monthly from January to December, 2012. We identified 61 species belonging to 33 genera, including 45 Rotifera belonging to 22 genera, 7 Cladocera belonging to 4 genera and 9 Copepoda belonging to 7 genera., Dominant species included Copepoda species Limnoithona sinensis and nauplii, ten Rotifera species, while Cladocera had no dominant species. Dominant species were different in each season. The annual average density of zooplankton was 1200 ind./L and the annual average biomass was 1.67mg/L. Zooplankton species number, density and biomass were all higher in spring and summer than in autumn and winter. The annual average of Shannon-Wiener and Margalef diversity indices were 1.61 and 1.01 respectively. Both of these diversity indices were significantly different in different seasons, but not significantly different between the eight sampling sites. Pearson Correlation analysis, Multiple Regression Analysis and Redundancy analysis (RDA) of species number, density and biomass of zooplankton and environmental factors displayed a significant relationship between zooplankton community and environmental factors. This indicated that the seasonal variation of zooplankton community structures in Dishui Lake was closely related to the water eutrophication status. Water temperature was a key factor in variation in the zooplankton community structure, and chlorophyll a, pH, total nitrogen (TN) and total phosphorus (TP) were also important factors. Zooplankton species number, density and biomass increased with a rise in water temperature and a decline in pH. TN increased the density and biomass, but excess TP tended to reduce the number of species present. Several methods were used to assess the water quality and eutrophication levels. Results showed that the water quality status of Dishui Lake in 2012 could be classified as α-mesosaprobic and its eutrophication level was at semi-eutrophic levels under a comprehensive application of the water quality index, trophic level index (TLI) and diversity indices assessment methods. 参考文献 相似文献 引证文献

제주도 주변 해역 조하대 해조류 군집구조의 계절적 변동

Marine macroalgal community structures and characteristics of ocean environmental factors were examined seasonally at four sites in Jeju Island, Korea, from March to November 2012. A total of 71 macroalgal species were identified, including 9 green, 7 brown, and 55 red algae. Peyssonnelia capensis occurred at all study sites and in all seasons. The average annual biomass of seaweed was 991.84 g wet , with seasonal variations from 543.80 g in autumn to 1,284.17 in summer. A green alga, Codium coactum, was the dominant species, occupying 21.31% (211.39 ) of the total algal biomass in Jeju Island. Subdominant species were Ecklonia cava and Lithophyllum okamurae, comprising 20.85% (206.75 ) and 19.64% (194.75 ), respectively, of the total algal biomass in Jeju Island. The vertical distribution of subtidal seaweeds was represented by L. okamurae at 5 m depth, C. coactum at 10 m depth, E. cava at 5-10 m depth and P. capensis at the 20 m depth level. In the present study, crustose coralline algae, which predominated on barren ground, were subdominant species at all study sites. Community indices varied between 0.51-0.63 for dominance index (DI), 5.53-8.14 for richness index (R), 0.51-0.63 for evenness index (J`), and 2.04-2.32 for diversity index (H`). On the basis of seaweed biomass and community indices, Sinchang was the best preserved coastal area, showing maximal values in biomass, and evenness- and diversity-indices, and minimal value in the dominance index, representing stable environmental conditions. In contrast, the Onpyung and Topyeong sites, located near tourist venues such as Udo and Seogwipo were relatively poor habitats based on community indices and biomass. The present results could imply that climate changes alter seaweed community structure, and long-term monitoring of the study sites is required.

Long‐term biomass yields of giant reed, mimosa and switchgrass in Alabama

AbstractThe US Department of Energy conducted two studies to estimate the potential of cellulosic biomass crops for production of biofuels on a national scale. However, limited long‐term experimental information is available to support the resultant yield projections. The objectives of this research were: (i) to determine long‐term (>10 years) biomass yields and soil impacts of switchgrass (Panicum virgatum L.), giant reed (Arundo donax L.) and mimosa (Albizia julibrissin Durazz.) in Alabama; and (ii) to establish relationships between precipitation and yields of these perennial biomass crops, and yields of cotton, maize, and soybean. Mimosa and giant reed received no fertilizer and were harvested once each year while switchgrass received 84 kg ha–1 of N fertilizer annually, and was harvested twice each year. Cotton, maize, and soybean were managed according to traditional practices for these crops in this region. Average annual biomass yields of mimosa, giant reed, and switchgrass were 40.1, 35.5 and 23.5 kg ha–1 over 16‐, 11‐ and 22‐year periods, respectively, with corresponding estimated annual N accumulation in aboveground biomass of 388, 372 and 163 kg ha–1. Yields of maize, cotton and soybean decreased sharply with decreasing precipitation, but there was no corresponding decrease in yield of the three perennial biomass crops. Changes in the yields of the biomass crops with age were also relatively small. Analysis of topsoil samples suggested considerably less removal of P, K, Ca, and Mg than was estimated from yield and concentrations of these elements in the biomass that was actually removed. © 2013 Society of Chemical Industry and John Wiley & Sons, Ltd

Comparison of two different bioenergy production options from late harvested biomass of Estonian semi-natural grasslands

Semi-natural grasslands are characterized by high biodiversity and can be maintained only with continuous management. In current situation, without sufficient demand for these biomass as cattle fodder, this source can be used for bioenergy production. In Estonia the largest average annual dry biomass yield per area was achieved in alluvial meadows (5.5 t ha−1) and the lowest in wooded meadows (1.9 t ha−1). Chemical characteristics of herbaceous biomass from wooded meadows differed from mesic and alluvial meadows resulting in the highest values of N, Ca, K, Mg and ash (1.3%, 2.4%, 0.3%, 10.9% and 9.5% of the dry matter, respectively) and lower ash softening temperature (1161 °C). The energy potential for combustion was estimated to be 102, 53 and 34 GJ ha−1 y−1 for alluvial, mesic and wooded meadows, respectively. The highest feedstock-specific methane yield can be produced from the biomass of wooded meadows (299 lN CH4 kg−1 VS (volatile solids)) and the lowest from alluvial meadows (269 lN CH4 kg−1 VS). The area-specific methane yield was obtained from 514 for wooded to 1375 m3 CH4 ha−1 for alluvial meadows that corresponds to 20 and 55 GJ ha−1. Via biogas production it is possible to achieve less than 60% of energy available for combustion.

Mapping biomass change after forest disturbance: Applying LiDAR footprint-derived models at key map scales

Accurate estimate of biomass and its changes at local to regional scales are important for a better understanding of ecosystem function, biodiversity and sustainability. In this study we explored the forest biomass prediction and dynamic monitoring from Light detection and ranging (LiDAR) waveform metrics at different key map scales. NASA's Laser Vegetation Imaging Sensor (LVIS) data were acquired in Penobscot County, Maine, USA, during August 2003 and 2009 airborne campaigns in the New England region. Field data were collected in 2003, and 2009 to 2011. Regression models developed at the scale of footprint were applied to all LVIS waveforms within the two study sites: Howland Forest (HF) and Penobscot Experiment Forest (PEF). The effect of forest disturbances on LVIS biomass prediction models was investigated. Two types of models, i. e. combined model without consideration of disturbances and disturbance-specific models were developed and compared. Field data from nested field plots of 0.25ha, 0.5ha and 1.0ha were used to evaluate the averaged, footprint-level (~0.03ha, 20m diameter) estimates in these plots. The results demonstrate that: 1) prediction model at the scale of individual LVIS footprints is reliable when the geolocations of the measured footprints were determined by DGPS with a best accuracy of 0.5–1.0m. 2) The differences between biomass prediction models for disturbed and undisturbed forests were statistically significant (p<0.001) at the scale of footprint, and the disturbance-specific models performed slightly better (R2=0.89, RMSE=27.9Mg·ha−1, and relative error of 22.6%) than the combined model (R2=0.86, RMSE=31.0Mg·ha−1, 25.1%). 3) The evaluation using field plot data showed that the predictions of biomass were improved markedly with the increase of plot sizes from 0.25ha to 1.0ha and that the effect of disturbance was not strong. At 1.0ha plot-level, both disturbance-specific and combined models agreed well with field estimates (R2=0.91, 23.1Mg∙ha−1, 16.1%; and R2=0.91, 22.4Mg·ha−1, 15.6%). 4) Sensitivity analysis on levels of variation and error to footprint density suggests that a certain density of LVIS footprints is required for biomass mapping. The errors were minimized when footprint coverage approached about 50% of the area of 1.0ha plots (16 footprints). 5) By applying the footprint-level models developed from 2009 LVIS data to both 2009 and 2003 LVIS data, the change of biomass from 2003 to 2009 could be assessed. The average annual biomass reduction rate from forest disturbance at two sites is −7.0Mg·ha−1 and −6.2Mg·ha−1, the average annual biomass accumulation from regrowth is +4.4Mg·ha−1 and +5.2Mg·ha−1, respectively.

Estimating Aboveground Biomass and Average Annual Wood Biomass Increment with Airborne Leaf-on and Leaf-off LiDAR in Great Lakes Forest Types

Estimating Aboveground Biomass and Average Annual Wood Biomass Increment with Airborne Leaf-on and Leaf-off LiDAR in Great Lakes Forest Types

Looking for patterns in the phytoplankton community of the Mediterranean microtidal Venice Lagoon: evidence from ten years of observations

By analysing a ten-year series (1998-2007) of data on hydrochemical properties, phytoplankton abundance and species composition in the Venice Lagoon, we identified i) the average annual phytoplankton biomass cycle, mainly unimodal and fairly well tuned with the fluctuations in temperature and irradiance and (ii) the seasonal succession of the most important species, allowing us to construct a “phytoplankton calendar”. Phytoplankton biomass was significantly lower in the second half of the ten-year period (2003-2007) than in the first half (1998-2002).

Biomass production of four willow clones grown as short rotation coppice on two soil types in Denmark

Ambitious targets for reducing emissions of carbon dioxide have created a demand for renewable sources of energy. Short rotation coppice (SRC) willow has the potential for meeting part of this demand. In this study, an experiment including four commercial clones of willow grown on two different soil types in northern Denmark is reported. Annual biomass production was estimated after the first and second growing season in the first rotation using a non-destructive method and total biomass production was measured by harvesting of the willow after the second growing season. The non-destructive method showed a large increase in annual biomass production from the first to the second growing season. Based on the harvested willow, average annual biomass production of the four clones ranged from 5.2 to 8.8 odt ha−1 yr−1 with a significant effect of both soil type and clone. The interaction between clones and soil types was also significant, indicating that different clones may be better suited for different soil types. On average, estimates of annual biomass production obtained by non-destructive estimation exceeded those obtained by destructive methods by 1.2 odt ha−1 yr−1. This bias indicates a need to revise commonly used methods for assessment of biomass production in SRC willow.

Biogeochemical cycling in terrestrial ecosystems of the Caatinga Biome

The biogeochemical cycles of C, N, P and water, the impacts of land use in the stocks and flows of these elements and how they can affect the structure and functioning of Caatinga were reviewed. About half of this biome is still covered by native secondary vegetation. Soils are deficient in nutrients, especially N and P. Average concentrations of total soil P and C in the top layer (0-20 cm) are 196 mg kg(-1) and 9.3 g kg(-1), corresponding to C stocks around 23 Mg ha(-1). Aboveground biomass of native vegetation varies from 30 to 50 Mg ha(-1), and average root biomass from 3 to 12 Mg ha(-1). Average annual productivities and biomass accumulation in different land use systems vary from 1 to 7 Mg ha(-1) year(-1). Biological atmospheric N2 fixation is estimated to vary from 3 to 11 kg N ha(-1) year-1 and 21 to 26 kg N ha(-1) year(-1) in mature and secondary Caatinga, respectively. The main processes responsible for nutrient and water losses are fire, soil erosion, runoff and harvest of crops and animal products. Projected climate changes in the future point to higher temperatures and rainfall decreases. In face of the high intrinsic variability, actions to increase sustainability should improve resilience and stability of the ecosystems. Land use systems based on perennial species, as opposed to annual species, may be more stable and resilient, thus more adequate to face future potential increases in climate variability. Long-term studies to investigate the potential of the native biodiversity or adapted exotic species to design sustainable land use systems should be encouraged.

Rotifer community structure and assessment of water quality in Yangcheng Lake

Rotifer community structure was investigated in Yangcheng Lake in 2008. Dominant species and species diversity indices were determined and QB/T was used to assess water quality. The annual average density and biomass of the rotifers in Yangcheng Lake was 2 894 ± 1 006 ind./L and 12.47 ± 10.28 mg/L, respectively. The highest densities were observed in the western portion of the lake in March, but the highest biomass occurred in inflowing creeks in September. Within a year of monitoring in Yangcheng Lake, 93 species were identified and the dominant species were found to be Polyarthra trigla, Brachionus angularis, Keratella cochlearis, Keratella valga, Brachionus calyciflorus, and Filinia major. Of the species recorded, 75 were pollution indicator species. Density and biomass exhibited significant positive correlations with water temperature (R = 0.209, P = 0.003; R = 0.446, P = 0.000), but the peak density showed two lags in response to chl a. According to the Jaccard similarity index (SJ), the greatest similarity among dominant species occurred between creeks and the eastern part of the lake. The annual average Shannon-Wiener diversity index H′, Margalef richness index D and Pielou evenness index J were 1.96 ± 0.34, 1.61 ± 0.50 and 0.77 ± 0.10, respectively. In all four areas of Yangcheng Lake, β-mesosaprobic species comprised the largest share of pollution indicator species. These data suggest that Yangcheng Lake is mesosaprobic.

Temporal and spatial patterns of &lt;i&gt;Limnodrilus hoffmeisteri&lt;/i&gt; Clapar&amp;#232;de in Lake Taihu

2005年1-12月对太湖霍甫水丝蚓进行了逐月调查.太湖霍甫水丝蚓年均密度和生物量分别为3273.75 ind./m²和4.697 g/m²,均在2月份达到最大值.根据体长频数分布的周年变化,推测太湖霍甫水丝蚓一年有三代.太湖霍甫水丝蚓密度和生物量在空间上表现出明显的差异性,且随季节变化较小,其高值区域均出现在太湖北部梅梁湾和竺山湾及西部河口湖区,而在其它区域的现存量均较低.分析表明太湖霍甫水丝蚓空间差异可能与营养水平、底质类型、可摄食的食物及生境的稳定性等因素有关.;The population of Limnodrilus hoffmeisteri Claparède in Lake Taihu (Eastern China) was investigated in 2005 by monthly sampling. The annual average density and biomass of this worm were 3273.75 ind./m² and 4.697 g/m², respectively. Both population density and biomass peaked in February. According to the annual dynamics of the frequency distributions of body length, the species had three generations and reproduced in considerable time throughout the year. The results showed a strong clumped distribution pattern of L. hoffmeisteri but it changed little among seasons. The highest population density and biomass of L. hoffmeisteri were found in Meiliang Bay, Zhushan Bay and the river-mouths areas in the west, while other places of the lake had very low worm density. The key factors regulating this spatial distribution pattern may be nutrient state, types of substrate, food availability and habitat stability.

Corrigendum to: Annual secondary production of two estuarine mysid species (Mysidacea : Mysidae) inhabiting an intermittently closed estuary, south-eastern New Zealand

Estimates of secondary production are essential to understanding how communities function. Estimates of secondary production for key species such as mysids are scarce, especially in estuarine environments. There are no estimates for mysid production in intermittently closed estuaries in the world, and no estimates for endemic New Zealand mysids. The current study presents length?mass models for two mysid species (Tenagomysis chiltoni Tattersall, 1923 and T. novae-zealandiae Thomson, 1900) from the south-eastern coast of the South Island, New Zealand. Kaikorai Lagoon, a small intermittently closed estuary, supported a large average annual biomass of T. novae-zealandiae (861.77 mg m?2) and T. chiltoni (971.90 mg m?2). The Hynes average-cohort method was used with length?mass models to estimate the annual production of breeding populations of T. chiltoni and T. novae-zealandiae collected over a year in parts of the Kaikorai Lagoon. Compared with similar temperate ecosystems worldwide, the studied ecosystem indicated high annual production (11 328.8 mg m?2 year?1 and 6585.2 mg m?2 year?1) and turnover rates (P : B) (13.16 and 6.78) for T. novae-zealandiae and T. chiltoni, respectively. High annual secondary production may be due to relatively stable hydrological and food conditions found in intermittently closed estuaries, leading to dense stable populations that are maintained through much of the year.

Dynamics of mesozooplankton assemblages in subtropical coastal waters of Hong Kong: A comparative study between a eutrophic estuarine and a mesotrophic coastal site

A monthly comparative study of mesozooplankton biomass and composition between a eutrophic Pearl River estuarine site (WE) and a mesotrophic coastal-oceanic site (EO) in Hong Kong waters was conducted to examine the response of mesozooplankton to nutrient-rich riverine discharge. Although the annual average mesozooplankton biomass was higher at WE than at EO, they were not statistically significant. Variations of mesozooplankton biomass at both stations followed similar trends of Chl a concentrations, with the exception of July at WE where mesozooplankton biomass was low but total Chl a was high. This mismatch may be due to the high flushing effect of the Pearl River discharge in summer and a time lag in mesozooplankton population growth. On the other hand, the composition of mesozooplankton was significantly modified by riverine discharge and eutrophication conditions. While small copepods dominated at both sites, the eutrophic estuarine water had a high abundance of barnacle and polychaete larvae, while cladocerans, bivalve larvae, gastropod larvae and chaetognaths mainly occurred at EO. Eutrophication increased the top-down role of copepods in the grazing community, revealed by an increase in the percentage of copepods in the total metazoan mesozooplankton, especially during the period of high river discharge. Moreover, mesozooplankton diversity at the two stations was similar, and they both showed relatively higher diversity during autumn and winter and lower diversity during summer, especially at WE. These results suggest that, despite high nutrient and Chl a concentrations in estuarine waters, mesozooplankton biomass were not enhanced compared to coastal waters with no river impact, possibly due to poor food quality and increased predation in the eutrophic estuarine waters.

Annual secondary production of two estuarine mysid species (Mysidacea: Mysidae) inhabiting an intermittently closed estuary, south-eastern New Zealand

Estimates of secondary production are essential to understanding how communities function. Estimates of secondary production for key species such as mysids are scarce, especially in estuarine environments. There are no estimates for mysid production in intermittently closed estuaries in the world, and no estimates for endemic New Zealand mysids. The current study presents length–mass models for two mysid species (Tenagomysis chiltoni Tattersall, 1923 and T. novae-zealandiae Thomson, 1900) from the south-eastern coast of the South Island, New Zealand. Kaikorai Lagoon, a small intermittently closed estuary, supported a large average annual biomass of T. novae-zealandiae (861.77 mg m–2) and T. chiltoni (971.90 mg m–2). The Hynes average-cohort method was used with length–mass models to estimate the annual production of breeding populations of T. chiltoni and T. novae-zealandiae collected over a year in parts of the Kaikorai Lagoon. Compared with similar temperate ecosystems worldwide, the studied ecosystem indicated high annual production (11 328.8 mg m–2 year–1 and 6585.2 mg m–2 year–1) and turnover rates (P : B) (13.16 and 6.78) for T. novae-zealandiae and T. chiltoni, respectively. High annual secondary production may be due to relatively stable hydrological and food conditions found in intermittently closed estuaries, leading to dense stable populations that are maintained through much of the year.

Seasonal Variability of Seaweed Biomass along the Vertical Shore Gradients of Nachido and Odo Islands, the Yellow Sea, Korea

Seasonal variation in seaweed biomass was examined along vertical shore gradients on the rocky shores of Nachido and Odo Islands, the Yellow Sea, Korea, from August 2007 to April 2008. The average annual biomass of seaweed was 404.07 g wet wt/<TEX>$m^2$</TEX>, with seasonal variation from 232.61 g in the spring to 754.90 g wet wt/<TEX>$m^2$</TEX> in the summer at Nachido Island. At Odo Island, average biomass was 270.82 g wet wt/<TEX>$m^2$</TEX> and ranged from 48.35 g in the winter to 451.66 g wet wt/<TEX>$m^2$</TEX> in the spring. Seaweed biomass exhibited an even distribution across the shore gradient from the high intertidal zone to -5 m depth at Nachido Island, whereas seaweed biomass was concentrated from the mid intertidal zone to -1 m depth in the subtidal zone at Odo Island. Sargassum thunbergii was the most dominant species, occupying 28.24% (114.12 g wet wt/<TEX>$m^2$</TEX>) and 36.57% (99.05 g wet wt/<TEX>$m^2$</TEX>) of total biomass at Nachido and Odo Islands, respectively. Subdominant seaweed species was Gelidium amansii, comprising 15.23% (61.52 g wet wt/<TEX>$m^2$</TEX>) and 14.70% (39.82 g wet wt/<TEX>$m^2$</TEX>) of total biomass at Nachido and Odo Islands, respectively. Dominant functional group was the coarsely branched-form group, which grows under moderate environmental conditions and comprised 93.34% (377.15 g wet wt/<TEX>$m^2$</TEX>) and 66.96% (181.35-g wet wt/<TEX>$m^2$</TEX>) of total biomass at Nachido and Odo Islands, respectively. Percentage biomass of sheet-form seaweeds growing at relatively disturbed and polluted areas was approximately 20.83% (56.40 g wet wt/<TEX>$m^2$</TEX>) of total biomass along the Odo rocky shore. Based on the biomass and functional-form composition of seaweeds, we concluded that Nachido Island provides better environmental conditions than does Odo Island. In addition, the vertical distribution and dominant species of seaweeds on the two islands were very similar, but the functional-form composition of seaweeds at Nachido Island differed slightly from that at Odo Island.

Long term changes of biodiversity of benthic macroalgae in the intertidal zone of the Nanji Islands

A long term observation on biodiversity and biomass of benthic macroalgae in Point 1 of the intertidal zone of the Nanji Islands, Zhejiang were carried out during 1959–2007, including three phases, i.e. 1959–1965, 1980–1985 and 2000–2007. The results show that the species of the benthic macroalgae there disappeared by 41.7%, and decreasing trend of the biodiversity has been getting quick; the community structure clearly shifted, i.e. the proportion of subtropical and warm-temperate species increased, and that of cold-temperate species decreased in the benthic macroalgae assemblage, particularly the calcareous nullipore became an absolutely dominant group. In comparison with the second phase (1980–1985), during the third phase the average annual biomass of the benthic macroalgae decreased by 52.5%; the average spring and winter biomass decreased by 54.1% and 87.2%; while the average summer and autumn biomass increased by 11.1% and 3.2%, respectively. The causes of the decrease in the biodiversity have been discussed, and the authors considered that the climate change and increase in CO 2 concentration have been the main reasons to lead berserk growth of the nullipore, resulting in desertification tendency of the intertidal zone of the Nanji Islands.

The potential of Estonian semi-natural grasslands for bioenergy production

High biodiversity of Estonian semi-natural grasslands can only be maintained through continuous management. One option for the usage of biomass from these areas is bioenergy production, if both the herbaceous biomass yield and the chemical characteristics of the cut meet the needs. In 2007 the largest average annual biomass yield per area was achieved in floodplain meadows (5.7 t dry mass/ha), which also have the highest potential for biomass production among Estonian semi-natural grasslands (more than 113,000 t dry mass). The area of mesic meadows is larger, but due to lower average yield per area (2.5 t dry mass/ha), the potential of this meadow type was less than half of that of floodplain meadows (53,000 t dry mass). The corresponding numbers for wooded meadows were 1.6 t dry mass/ha and 12,000 t dry mass, respectively. Chemical characteristics of herbaceous biomass from wooded meadows significantly differed from mesic and floodplain meadows, giving the highest values of Ca, K, Mg, crude protein and ash (1.3%, 2.4%, 0.3%, 10.9% and 9.5% of the dry biomass, respectively). The energetic value of the biomass from different meadow types varied between 18.1 kJ/g and 18.6 kJ/g. Therefore, various options for bioenergy conversion should be considered depending on the local plant community and restrictions to the harvest time.