Seasonal occurrence and diel locomotor activity in littoral Cladocera in a mesohumic lake in Norway

The community structure and standing crop biomass of a mangrove forest in Futian Nature Reserve, Shenzhen, the People's Republic of China was studied. This mangrove, located towards the northern latitudinal limit of the mangrove development (22°N), had relatively simple structure and low diversity (the Shannon-Wiener index was 0.78). The three dominant species, namely Aegiceras corniculatum, Kandelia candel and Avicennia marina, possess importance values of 72, 19 and 9%, respectively. The average height of the mangrove community was 4.5 m with no vertical stratification. The values of tree density of A. corniculatum and A. marina were found to be 5290 and 260 ha^–1, respectively. The biomass of both A. corniculatum and K. candel was best estimated from regression equations using a combination of height and diameter at breast height as the independent variables. For Avicennia marina, there was no simple correlation between biomass and height or diameter. The regression models suggested by previous workers did not give satisfactory estimation of biomass of A. marina in this mangrove forest. The total biomass of this mangrove forest was 12.1 kg m^–2, with 73% of such production contributed by A. corniculatum and 8% by A. marina. Because of its small percentage, the inaccuracy in estimating biomass of A. marina did not affect the overall determination of biomass of the whole community. Average above-ground biomass was 8.7 kg m^–2 (72% of the total biomass) and the major components were aerial woody tissues, stems and branches. The root:shoot ratio of this plant community was 0.4:1.     

The nematode fauna of a temperate Australian mangrove mudflat; its population density,diversity and distribution

The nematode fauna of an estuarine mangrove Avicennia marina mudflat in Southeastern Australia has been intensively studied. About 85% of the nematodes occur in the top cm of soft mud, but 5–7 species inhabit the deeper anoxic mud down to 10 cm, both at low and high tide. One square metre was intensively sampled from four zones with different nematode faunas. At the low tide zone 58% of the nematodes were epistrate feeders, including many diatom-feeders, but in the mangrove zone selective microbial feeders made up over 60% of the population, while between high water neap and high water spring, above the mangrove zone, omnivore/predators and plant root feeding nematodes increased in relative importance. Random replicate cores reliably sampled species occurrence, but gave a high variance in density estimates. Replicate aliquots from homogenised mud gave lower density variance. Nematode densities (maximum 5 × 10⁶ m^-2) were not as high as have been reported from non-mangrove estuaries in other countries, but were within the range found in mangroves elsewhere in Australia. Margalef Species Richness values ranged from 1.7 to 3.89, which is similar to values found in other mangroves mudflats in Australia. Nematode biomass ranged from 888 mg dry weight m² (383 mg C m^-2) at the low tide zone to 19 mg dry weight m^-2 (8 mg C m^-2) at the upper tide level.     

Mangrove litter dynamics in La Mancha Lagoon,Veracruz, Mexico

In the mangrove surrounding the coastal lagoon of La Mancha, Veracruz, Mexico, we studied litter fall, litter standing crop, and turnover rates in four different mangrove settings, based on the ecological classification of Lugo and Snedaker (1974). We studied those three prominent ecological processes at the basin, fringe and riverine mangrove settings, being the last one a relict riverine stand. The aim was to describe and compare litter dynamics among mangrove types in a lagoon with an ephemeral inlet, as a way of understanding functional heterogeneity within this coastal ecosystem. The daily average values of litter fall were different (P < 0.01) among mangrove site basin I, formed by Avicennia germinans and Rhizophora mangle (2.35 g/m²/day); basin II, formed by Laguncularia racemosa, Avicennia germinans, and Rhizophora mangle (2.93 g/m²/day); fringe with Rhizophora mangle (2.13 g/m²/day); and relic riverine, also with R. mangle (4.70 g/m²/day). The amount of litter standing crop was different among sites (P < 0.001), and also between the dry and rainy season, for each mangrove type (P < 0.001). Turnover ratios were higher in basin I and basin II sites (6.34 and 7.44 times per year) than in relic riverine and fringe mangroves (1.49 and 2.39 times per year). Interstitial salinity and sediment nutrients varied among mangrove types and could influence litter production. Since this lagoon has an ephemeral inlet, continuous inundation throughout 7–8 months per year has an important effect on litter dynamics.     

重金属镉对红树植物白骨壤和桐花树幼苗生理特性的影响

通过砂泥栽培实验研究了红树植物桐花树和白骨壤幼苗在含Cd 0.6～30 mmol·L~(-1)系列海水培养液中某些生理特性的变化。当培养液中Cd浓度为0.6 mmol·L~(-1)时桐花树和白骨壤幼苗生长正常,叶绿素含量和光合速率变化不大。当高于12 mmol·L~(-1)时,除桐花树和白骨壤幼苗除POD酶活性越来越高之外,叶绿素含量、光合速率、SOD、CAT酶活性均不断减弱,而且浓度愈高,这些指标下降愈大。结果表明Cd对红树植物桐花树和白骨壤幼苗具有毒害作用,Cd浓度愈高对其毒害愈严重,两种红树植物比较,桐花树抗重金属镉毒害的能力大于白骨壤。     

挖捕泥丁对红树植物白骨壤幼苗生长影响的模拟

沿海群众为了增加收入挖掘林下滩涂海洋经济动物可口革囊星虫,这是导致中国红树林退化的一个重要原因.本文研究了挖掘深度、弧度和频率3个因素对1年生白骨壤幼苗的苗高、基径、单叶面积、比叶面积、生物量和死根干质量等生长指标的影响,了解挖掘活动对红树林生长的影响机理,并筛选出红树林健康状况的评估指标.结果表明:挖掘活动使白骨壤幼苗的苗高和基径增长量、单叶面积、比叶面积和生物量显著减少,而死根干质量显著增加;挖掘深度和弧度对幼苗生长具有明显影响,但频率的影响不显著;当挖掘深度＜5 cm、弧度＜240°、每月2次以下时,对幼苗的伤害较轻,而挖掘深度＞5 cm则会对幼苗造成严重影响.     

大亚湾红树林研究I.澳头港的红树植物群落

本文报道了大亚湾澳头港附近的红树植物群落的种类组成、结构、外貌及演替。该地区红树群落的主要类型有7个,即白骨壤群落、白骨壤-桐花树群落、白骨壤+秋茄-桐花树群落、海漆-木榄群落、海漆-桐花树群落、桐花树群落、老鼠勒群落。     

Spatial and temporal distribution of Myrophis punctatus (Ophichthidae) and associated fish fauna in a northern Brazilian intertidal mangrove forest

The mangrove forest along the northern Brazilian coast is not inundated during low tide. However, many fish species stay in the mangrove forest during this time. Tidal behaviour strategies are described for fish species that linger in the mangrove forest during low tide. The samples were taken at the end of the dry season (December 1996) and at the end of the rainy season (July 1997). Fish were captured using an ichthyotoxic plant extract (Ichthyotere cunabi). Spatial and temporal fish density and biomass were analyzed statistically. Thirty-six samples were taken with a total density of 2.8 ind m^-2 and a total biomass of 17.4 g m^-2 distributed among seven families and 14 species. Myrophis punctatus was the most important species in number (1.66 ind m^-2) and weight (12.68 g m^-2) of all catches. The total fish densities were not significantly different among areas and between months, although, total biomass differed significantly in time and space. The densities and biomass for the three most dominant species (M. punctatus, Poecilia spp. and Gobionellus smaragdus) differed significantly among species. Only the biomass of these species showed significant monthly differences. The only significant main effect on variance in the densities and biomass of M. punctatus were encountered between months. In addition, the factor area was significantly different for the variable number of species.     

Seed predation by insects in tropical mangrove forests: extent and effects on seed viability and the growth of seedlings

Summary Although insects are known to be important seed predators in most terrestrial forests, their role in marine tidal (mangrove) forests has not been examined. Surveys at 12 sites in tropical Australia showed that between 3.1 and 92.7 percent of the seeds or propagules of 12 mangrove tree species had been attacked by insects. Seeds/propagules of six species (Avicennia marina, Bruguiera gymnorrhiza, B. parviflora, Heritiera littoralis, Xylocarpus australasicus and X. granatum) showed consistently high (>40%) levels of insect damage. Greater than 99% of H. littoralis seeds were attacked by insect predators. The survival and subsequent growth in height and biomass of insect-damaged and non-damaged control seeds/propagules of eight mangrove species were compared in shadehouse experiments. Mangrove species fell into 4 groups with regard to the effect of insect predators on their seeds and seedlings. Xylocarpus australasicus and X. granatum had significantly decreased survival (X 48 and 70%) and growth in height (X 61 and 96%) and biomass (X 66 and 85%). Bruguiera parviflora showed decreased survival (X 59%), but there was no effect of insects on the growth of surviving propagules. In contrast, there was no effect of insect damage on the survival of seedlings of Avicennia marina and Bruguiera exaristata, but decreased growth in height (X 22 and 25%) and biomass (X 22 and 26%). Survival and growth of seedlings of Rhizophora stylosa and Bruguiera gymnorrhiza were not affected. The influence of insect seed predators on the survival and growth of seeds of mangrove species in forests will depend on the relative abundance of seed-eating crabs and intertidal position in mangrove forests.This is Contribution No 499 from the Australian Institute of Marine Science     

Live and dead underground plant biomass in a natural meadow hydrosere

In seven meadow stands of natural hydroseres the average total underground biomass ranged from 1.6 to 3.7 kg. m^?2. The highest percentages of live roots (46–60%) and live underground biomass (1.40–1.61 kg. m^?2) were recorded in stands situated around the middle of the hydroseres and the lowest values (18%; 0.48 kg. m^?2 and 23%; 0.86 kg. m^?2) were both on the wettest and the driest sites. The total underground/aboveground biomass ratios varied between 3.2 and 12.2 while the live underground/aboveground biomass ratios lay between 0.7 and 3.4.     

红树林恢复初期莱氏锥滨螺分布动态

树栖腹足类动物是红树林底栖动物的重要组成部分,其组成和分布受到红树植被的影响。因此,在红树林生态修复中,腹足类动物的恢复依赖于植被的发育。滨螺科(Littorinidae)锥滨螺属(Mainwaringia)动物是亚洲红树林的广布种,但针对其在红树林中的分布及种群特征的研究较少,对红树林植被恢复过程中锥滨螺属动物的恢复动态更是鲜有研究。调查了厦门下潭尾湿地秋茄(Kandelia obovata)红树林恢复初期,新记录种莱氏锥滨螺(Mainwaringia leithii)种群恢复的时间动态,并分析其与植被参数的关系。研究发现,红树林恢复初期,秋茄植被生长迅速,株高、冠幅、基径和覆盖度分别由0.5年生幼林的41.3 cm、25.0 cm、1.04 cm和25%增长为8年生样地的179.2 cm、76.7 cm、5.96 cm和95%。在秋茄胚轴种植6个月左右开始记录到莱氏锥滨螺的个体,其密度和生物量在1.5 a后达到最大(分别为136个/m²和1.86 g/m²),而后逐渐降低,种植3 a后秋茄林内莱氏锥滨螺仅零星分布。除8年生的样地,莱氏锥滨...     

Standing crop and aboveground biomass partitioning of a dwarf mangrove forest in Taylor River Slough,Florida

The structure and standing crop biomass of a dwarf mangrove forest, located in the salinity transition zone ofTaylor River Slough in the Everglades National Park, were studied. Although the four mangrove species reported for Florida occurred at the study site, dwarf Rhizophora mangle trees dominated the forest. The structural characteristics of the mangrove forest were relatively simple: tree height varied from 0.9 to 1.2 meters, and tree density ranged from 7062 to 23 778 stems ha^–1. An allometric relationship was developed to estimate leaf, branch, prop root, and total aboveground biomass of dwarf Rhizophora mangle trees. Total aboveground biomass and their components were best estimated as a power function of the crown area times number of prop roots as an independent variable (Y = B × X^–0.5083). The allometric equation for each tree component was highly significant (p<0.0001), with all r² values greater than 0.90. The allometric relationship was used to estimate total aboveground biomass that ranged from 7.9 to 23.2 ton ha^–1. Rhizophora mangle contributed 85% of total standing crop biomass. Conocarpus erectus, Laguncularia racemosa, and Avicennia germinans contributed the remaining biomass. Average aboveground biomass allocation was 69% for prop roots, 25% for stem and branches, and 6% for leaves. This aboveground biomass partitioning pattern, which gives a major role to prop roots that have the potential to produce an extensive root system, may be an important biological strategy in response to low phosphorus availability and relatively reduced soils that characterize mangrove forests in South Florida.     

广东湛江保护区红树林种群的生物量及其分布格局

本文研究了广东湛江红树林自然保护区高桥镇红寨村及德耀村海滩红树植物的种群分布格局与生物量。结果表明：５年生桐花树群落、白骨壤群落、秋茄群落、１０年生木榄群落、３０年生红海榄群落的总生物量分别为５５４７５ｇ／ｍ２、１６３７０１ｇ／ｍ２、６２６４４８ｇ／ｍ２、４１３８４３ｇ／ｍ２、９６１０２０ｇ／ｍ２;其中地下部分生物量占总生物量的比例依次为３２２８％、４５４５％、４１３１％、２９８５％和２８２９％。计算得Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ物种多样性指数为２２３２。种群的分布格局中桐花树、白骨壤、红海榄和秋茄种群为集群分布,而木榄种群为随机分布。     

深圳福田红树植物群落特征及金属元素分布状况

通过对深圳福田红树林群落特征的研究,对红树植物的区系组成、群落的外貌和结构、群落的主要类型和分布进行了概述,并对该红树林中的桐花树+秋茄+白骨壤+老鼠簕+海漆混交群落林地土壤和红树植物的金属元素分布进行分析。结果发现,该林地土壤金属元素含量分布具有一定规律性,元素K、Na、Ca、Mg在各层土壤中分布均匀;必需金属元素Fe、Mn在各层土壤中含量变化不明显;非必需重金属元素Cr、Ni、Pb、Hg、Cd和必需元素Zn、Cu含量从底层至表层逐步提高;金属元素在该林地红树植物中分布也具有一定规律性,元素K、Na、Ca、Mg在五种红树植物的不同部位均大量存在;必需金属元素Fe、Mn、Zn、Cu在各种红树植物中含量FeMnZnCu;非必需重金属元素Cr、Ni、Pb、Hg、Cd在各种红树植物中含量表现出差异性,秋茄和海漆中Ni含量较大,白骨壤中Pb含量最大,桐花树中Cr含量最大,老鼠簕Cu含量最大,Cd和Hg在五种红树植物中含量都最低;植物中金属元素含量分布和土壤中金属元素含量分布具有相关性。     

Woody Debris in the Mangrove Forests of South Florida1

Woody debris is abundant in hurricane‐impacted forests. With a major hurricane affecting South Florida mangroves approximately every 20 yr, carbon storage and nutrient retention may be influenced greatly by woody debris dynamics. In addition, woody debris can influence seedling regeneration in mangrove swamps by trapping propagules and enhancing seedling growth potential. Here, we report on line‐intercept woody debris surveys conducted in mangrove wetlands of South Florida 9–10 yr after the passage of Hurricane Andrew. The total volume of woody debris for all sites combined was estimated at 67 m³/ha and varied from 13 to 181 m³/ha depending upon differences in forest height, proximity to the storm, and maximum estimated wind velocities. Large volumes of woody debris were found in the eyewall region of the hurricane, with a volume of 132 m³/ha and a projected woody debris biomass of approximately 36 t/ha. Approximately half of the woody debris biomass averaged across all sites was associated as small twigs and branches (fine woody debris), since coarse woody debris >7.5 cm felled during Hurricane Andrew was fairly well decomposed. Much of the small debris is likely to be associated with post‐hurricane forest dynamics. Hurricanes are responsible for large amounts of damage to mangrove ecosystems, and components of associated downed wood may provide a relative index of disturbance for mangrove forests. Here, we suggest that a fine:coarse woody debris ratio ≤0.5 is suggestive of a recent disturbance in mangrove wetlands, although additional research is needed to corroborate such findings.     

Nematode numbers,biomass and respiratory metabolism in a beech woodland—Wytham Woods,Oxford

Summary The mean annual population density of nematodes in the litter and upper 6 cm of soil was found to be 368,000 m^-2. Mean individual live weight biomass approximated 0.2 g and mean biomass was calculated to be 74.6 mg live weight m^-2. No evidence of seasonal vertical migration between the litter, 0–3 cm and 3–6 cm strata was found and on average these strata contained 21.9, 46.2 and 31.9% respectively of the total number of nematodes recovered. The equivalent biomass values were 26.14, 56.57, and 17.29%. Total numbers revealed a general picture of low densities in spring and high ones in early winter, whereas biomass m^-2 was low in late summer — autumn and high in winter. The annual oxygen consumption of the extracted nematodes was calculated to approximate 0.211 m^-2 (4.0 kJ m^-2) but when corrected for the effect of individual biomass (weight specific oxygen uptake) was equivalent to an energy expenditure 6.0 kJ m^-2 which in its turn, because of the efficiencies of extraction, probably accounts for only 87% of the total energy expenditure by the nematode fauna. The nematodes were estimated to be responsible for a minimum of 0.11% to a maximum of 0.13% of the total soil respiration. A production/biomass ratio of 5.16 was estimated as was a net population production efficiency of 36.63%.     

深圳湾福田红树林群落演替

对深圳湾福田凤塘河红树林演替过程中的群落结构、物种组成、多样性变化及演替趋势的研究结果表明:(1)演替各阶段群落均由秋茄(Kandelia candel)、木榄(Bruguiera gymnorrhiza)、桐花树(Aegiceras corniculatum)、白骨壤(Avicennia marina)及老鼠簕(Acanthus ilicifolius)5个种类组成。(2)演替早期(4 a)群落高度增长较快,之后继续保持较快增长,至17 a时趋于稳定,之后增长速度缓慢。(3)4 a和17 a的群落立木级均分布在Ⅱ级—Ⅳ级,56 a和73 a的群落立木均达到最高级Ⅴ级,该两群落立木在Ⅱ级—Ⅴ级均有分布。(4)随着演替的进展,除了73 a群落盖度较56 a群落稍有下降外,其它演替群落盖度逐渐增加;群落胸高断面积表现出与盖度一致的变化趋势;群落个体密度则逐渐下降;群落物种多样性和均匀度不断提高,群落优势度则逐渐下降;群落相似性系数的变化表明在演替过程中群落物种组成结构没有发生明显变化。(5)群落变化及演替为:秋茄+桐花树群落→秋茄群落→白骨壤+秋茄群落→白骨壤群落。     

广西西端海岸四种红树植物天然种群生境高程

在广西防城港市东湾渔洲坪、石角、交东3个样地平行海面方向共设置18条剖面对4种红树植物白骨壤(Avicenniamarina)、桐花树(Aegiceras corniculatum)、秋茄(Kandelia obovata)、木榄(Bruguiera gymnorhiza)在沿海滩涂生长带高程测量和群落调查。调查结果表明:由于人类活动造成东湾渔洲坪和交东两个样地的坡度变化较大,分别从-0.37变化为-0.05和-0.72变化为-0.10,而地处北仑河口保护区内的石角样地受到保护,没有人为因素的影响,坡度从-0.23变化为-0.10变化不大。石角和交东两个样地中的桐花树集中出现在高程15至40 cm和33至36 cm范围内;秋茄集中出现在高程43至60 cm和37至51cm范围内;木榄集中出现在高程94至106 cm和111至119 cm范围内。所有样地中的白骨壤在高程60至80 cm范围内,树高最高达到220 cm,且分布密集;桐花树在高程20至40 cm范围内,树高最高达到200 cm,且分布密集;秋茄在高程40至80 cm范围内,树高最高达到200 cm,且分布密集;木榄在高程60至100 cm范围内,且分布密集,树高最高达280 cm。通过对各样地剖面上红树植物种类出现频度的分析和林木高度的测量,4种红树植物天然林临界滩涂高程分别为:桐花树为-7 cm;秋茄为+33 cm;白骨壤为+23和+26 cm;木榄为+44 cm。对应的浸淹时间分别为8.5、7.0、7.0、6.0h。在石角和交东分别有30.0%和56.7%的桐花树分布于平均海平面以下,秋茄也能分布在此高程下,平均株高也达1.75 m。根据现场实际调查结果,桐花树、秋茄可以大量生存在平均海平面以下的滩涂上。     

A note on the root development in dry tropical naturally revegetated coalmine spoils

Root biomass distribution on an age series of naturally revegetated coalmine spoils in a dry tropical environment is described. 65 to 85% of the total root biomass was observed in the upper 0–15 cm of spoil depth. Highest (724 g m^-2) and lowest (186 g m^-2) values of root biomass were found on 12-yr old protected flat surfaces and 5-yr old grazed undulating sites, respectively. There is an increase in root biomass with increase in age of coalmine spoil.     

Patterns of Root Dynamics in Mangrove Forests Along Environmental Gradients in the Florida Coastal Everglades,USA

Patterns of mangrove vegetation in two distinct basins of Florida Coastal Everglades (FCE), Shark River estuary and Taylor River Slough, represent unique opportunities to test hypotheses that root dynamics respond to gradients of resources, regulators, and hydroperiod. We propose that soil total phosphorus (P) gradients in these two coastal basins of FCE cause specific patterns in belowground biomass allocation and net primary productivity that facilitate nutrient acquisition, but also minimize stress from regulators and hydroperiod in flooded soil conditions. Shark River basin has higher P and tidal hydrology with riverine mangroves, in contrast to scrub mangroves of Taylor basin with more permanent flooding and lower P across the coastal landscape. Belowground biomass (0–90 cm) of mangrove sites in Shark River and Taylor River basins ranged from 2317 to 4673 g m⁻², with the highest contribution (62–85%) of roots in the shallow root zone (0–45 cm) compared to the deeper root zone (45–90 cm). Total root productivity did not vary significantly among sites and ranged from 407 to 643 g m⁻² y⁻¹. Root production in the shallow root zone accounted for 57–78% of total production. Root turnover rates ranged from 0.04 to 0.60 y⁻¹ and consistently decreased as the root size class distribution increased from fine to coarse roots, indicating differences in root longevity. Fine root biomass was negatively correlated with soil P density and frequency of inundation, whereas fine root turnover decreased with increasing soil N:P ratios. Lower P availability in Taylor River basin relative to Shark River basin, along with higher regulator and hydroperiod stress, confirms our hypothesis that interactions of stress from resource limitation and long duration of hydroperiod account for higher fine root biomass along with lower fine root production and turnover. Because fine root production and organic matter accumulation are the primary processes controlling soil formation and accretion in scrub mangrove forests, root dynamics in the P-limited carbonate ecosystem of south Florida have a major controlling role as to how mangroves respond to future impacts of sea-level rise.