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1.
海堤对广西沿海红树林的数量,群落特征和恢复的影响   总被引:20,自引:1,他引:19  
广西大陆海岸线的 63%为海堤 ,海堤数量达 498个 .海堤建立毁灭了原生红树林 ,现余 5654hm2 ,其中约 85%为堤前红树林 .海堤阻截了红树林滩涂的自然海岸地貌 ,结果是红海榄和木榄已很少 ,榄李濒危 ,角果木已消失 ,海漆和陆岸种类只能沿海堤坡面生长 ,而先锋红树植物白骨壤和桐花树成为现有红树林的优势种 .堤前红树林的恢复受到海堤维护时强烈的人为干扰 .堤前滩涂相对于平均海平面的高程较低 ,不是红树林繁盛的理想滩涂 .红树林人工造林的成活率和次生林恢复的速率在很大程度上取决于生境的沉积率 .  相似文献
2.
Organic carbon dynamics in mangrove ecosystems: A review   总被引:18,自引:11,他引:7  
Our current knowledge on production, composition, transport, pathways and transformations of organic carbon in tropical mangrove environments is reviewed and discussed. Organic carbon entering mangrove foodwebs is either produced autochthonously or imported by tides and/or rivers. Mangrove litter and benthic microalgae are usually the most important autochthonous carbon sources. Depending on local conditions, phytoplankton and seagrass detritus imported with tides may represent a significant supplementary carbon input. Litter handling by the fauna not only affects microbial carbon transformations, but also the amount of organic carbon available for export. Most mangrove detritus that enters the sediment is degraded by microorganisms. Aerobic respiration and anaerobic sulfate reduction are usually considered the most important microbial respiration processes, but recent evidence suggests that iron respiration may be important in mangrove sediments as well. Organic carbon that escapes microbial degradation is stored in sediments and in some mangrove ecosystems, organic-rich sediments may extend to several meters depth. Many mangrove forests also lose a significant fraction of their net primary production to coastal waters. Large differences occur between mangrove forests with respect to litter production and export. Mangrove-derived DOC is also released into the water column and can add to the total organic carbon export. Numerous compounds have been characterized from mangrove tissues, including carbohydrates, amino acids, lignin-derived phenols, tannins, fatty acids, triterpenoids and n-alkanes. Many of these may, together with stable isotopes, exhibit a strong source signature and are potentially useful tracers of mangrove-derived organic matter. Our knowledge on mangrove carbon dynamics has improved considerably in recent years, but there are still significant gaps and shortcomings. These are emphasized and relevant research directions are suggested.  相似文献
3.
Summary Measurements of litter fall and litter removal by crabs, in conjunction with estimates of litter decay by microbes and tidal export of litter from three high-intertidal mangrove forests were made during a year-long study in tropical northeastern Australia. In forests dominated by Ceriops tagal and Bruguiera exaristata, litter standing stocks remained low on the forest floor (mean 6 g·m-2), although litter fall was high; 822 and 1022 g·m-2·y-1, respectively. Sesarmid crabs removed 580 (Ceriops) and 803 (Bruguiera) g·m-2·y-1, or 71 and 79%, of the total annual litter fall from the forest floor. Relative to the rate of litter removal by crabs, microbial turnover of whole, unshredded litter was insignificant, accounting for <1% of annual litter fall. Export of litter by tides was estimated to remove 194 (Ceriops) and 252 (Bruguiera) g·m-2·y-1 or 24 and 25% of annual litter fall. In a forest dominated by Avicenniamarina, in which an ocypodid crab was more abundant than sesarmids, litter standing stocks were higher (mean 84 g·m-2) and crabs removed less litter; 173 g·m-2·y-1 or 33% of the annual litter fall of 519 g·m-2·y-1. Microbial turnover of intact litter was more important in the Avicennia forest (168 g·m-2·y-1 or 32% of annual litter fall), and tides exported 107 g·m-2·y-1 or 21% of litter production. In areas where sesarmid crabs were absent or rare in Ceriops forests, there were significantly higher standing stocks of litter and slower rates of leaf removal. Taking into account the probable assimilation efficiencies of sesarmid crabs feeding on mangrove leaves, we estimate that in Ceriops and Bruguiera forests leaf processing by crabs turns litter over at >75 times the rate of microbial decay alone, thus facilitating the high sediment bacterial productivity in these forests. The importance of litter processing by crabs increases with height in the intertidal in tropical Australia, in contrast to New World mangrove forests, where the reverse is true.Contribution No. 445 from the Australian Institute of Marine Science  相似文献
4.
红树林有机碎屑在河口生态系统中的作用   总被引:9,自引:4,他引:5  
生长在热带、亚热带潮间带的红树林,由于其独特的生境和生物学特征,吸引了人们的好奇心,也引起人们对其科学价值的研究。人们首先注意到的是红树植物的形态适应特征(如胎生现象、支柱根和呼吸根等)和耐盐性。过去,人们对于红树林价值的认识是从直接用途开始的,如保护堤岸、提取丹宁、作为建筑材料和薪炭材等。早期的研究只注重于生物学  相似文献
5.
Preliminary estimates of the ratio of mangrove forest: shrimp pond area necessary to remove nutrients from shrimp pond effluent are made using budgets of nitrogen and phosphorus output for semi-intensive and intensive shrimp ponds combined with estimates of total net primary production in Rhizophora-dominated mangrove forests in tropical coastal areas. If effluent is delivered directly to mangrove forest plots, it is estimated that, depending on shrimp pond management, between 2 and 22 hectares of forest are required to filter the nitrogen and phosphorus loads from effluent produced by a 1 hectare pond. While such ratios may apply to small scale, integrated shrimp aquaculture — mangrove forestry farming systems, the variability in mangrove hydrodynamics makes it difficult to apply such ratios at a regional scale. Before mangroves can be used to strip shrimp pond effluent more research is required on the effects that high ammonia and particulate organic matter loads in pond effluent have on nutrient transformations in mangrove sediments and on forest growth.  相似文献
6.
7.
福建红树林区大型藻类的生态学研究   总被引:5,自引:0,他引:5  
主要研究中国福建省红树林区大型藻类分布、优势种的生物量和林冠下藻种的垂直分布特点。结果表明:福建红树林区的大型藻类有24属42种,其中蓝藻8属15种、红藻3属7种、绿藻13属20种。优势种中鹧鸪菜(Caloglossa leprieurii)和节附链藻(Catenella impudica)的生物量在6月分别为2.22~8.44g/m~2 DW和2.69g/m~2 DW,在12月分别为0.15~0.20g/m~2 DW和2.12g/m~2 DW。红树林中树干上附着生长的大型藻类的垂直分布自下而上可分成6个带:1.无隔藻(Vaucheria sp.)带;2、节附链藻带;3.侧枝鹧鸪菜-混合卷枝藻(Caloglossa ogasawaraensis-Bostrychia mixta)带;4.鹧鸪菜带;5.硬毛藻-岸生根枝藻(Chaetomorpha macrotona-Rhizoclonium riparium)带;6.绿球藻(Chlorococcum sp.)带。  相似文献
8.
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  相似文献
9.
10.
Studies on soil quality of mangrove forests would be of immense use in minimizing soil degradation and in adopting strategies for soil management at degraded sites. Among the various parameters of soil quality, biological and biochemical soil properties are very sensitive to environmental stress and provide rapid and accurate estimates on changes in quality of soils subjected to degradation. In this study, we determined the general and specific biochemical characteristics of soils (0-30 cm) of inter-tidal areas of 10 undisturbed mangrove forest sites of S. Andaman, India. In order to determine the effects of disturbance, soils from the inter-tidal areas of 10 disturbed mangrove forest sites were also included in the study. The general biochemical properties included all the variables directly related to microbial activity and the specific biochemical parameters included the activities of extracellular hydrolytic enzymes that are involved in the carbon, nitrogen, sulfur and phosphorus cycles in soil. The pH, clay, cation exchange capacity, Al2O3 and Fe2O3 levels exhibited minimum variation between the disturbed and undisturbed sites. In contrast, organic C, total N, Bray P and K levels exhibited marked variation between the sites and were considerably lower at the disturbed sites. The study also revealed marked reductions in microbial biomass and activity at the disturbed sites. In comparison to the undisturbed sites, the levels of all the general biochemical parameters viz., microbial biomass C, microbial biomass N, N flush, basal respiration, metabolic quotient (qCO2), ATP, N mineralization rates and the activities of dehydrogenase and catalase were considerably lower at the disturbed sites. Similarly, drastic reductions in the activities of phosphomonoesterase, phosphodiesterase, ß-g1ucosidase, urease, BAA-protease, casein-protease, arylsulfatase, invertase and carboxymethylcellulase occurred at the disturbed sites due mainly to significant reductions in organic matter/substrate levels. The data on CO2 evolution, qCO2 and ATP indicated the dominance of active individuals in the microbial communities of undisturbed soils and the ratios of biomass C:N, ATP:biomass C and ergosterol:biomass C ratios indicated low N availability and the possibility of fungi dominating over bacteria at both the mangrove sites. Significant and positive correlations between soil variables and biochemical properties suggested that the number and activity of soil microorganisms depend mainly on the quantity of mineralizable substrate and the availability of nutrients in these mangrove soils.  相似文献
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