广东湛江红树林保护区大型底栖动物群落的空间分带

用生态样带研究了广东湛江红树林保护区高桥镇核心区大型底栖动物的空间分带。结果表明：德耀村红树剖面中出现的大型底栖动物优势种类为琵琶拟沼螺、悦目大眼蟹、扁平拟闭口蟹、宽身闭口蟹、黑口滨螺、等齿角沙蚕、弧边招潮和中华伪露齿螺。该剖面大型底栖动物从高潮位到低潮位可分为3个分布带：琵琶拟沼螺-弧边招潮-浓毛拟闭口蟹带;宽身闭口蟹．悦目大眼蟹．黑口滨螺带;扁平拟闭口蟹-珠带拟蟹手螺带。群落生物量的变化主要由软体动物所主导,栖息密度的变化主要由软体动物和甲壳动物所主导,多样性指数变化主要由软体动物所主导。红寨村红树剖面中出现的大型底栖动物优势种类为琵琶拟沼螺、蝼姑虾、扁平拟闭口蟹、宽身闭口蟹、耳螺科的一种、黑口滨螺、中华伪露齿螺、哈氏仿对虾、弧边招潮和等齿角沙蚕。该剖面大型底栖动物也可分为4个分布带：黑口滨螺-中华伪露齿螺-等齿角沙蚕带;琵琶拟沼螺-宽身闭口蟹-耳螺科的一种带;蝼蛄虾．扁平拟闭口蟹带;沈氏长方蟹-珠带拟蟹守螺带。群落生物量的变化也主要由软体动物所主导,栖息密度的变化主要由甲壳动物所主导,多样性指数变化主要由软体动物所主导。底栖动物群落的等级聚类和非参数多变量标序显示,大型底栖动物分带与红树植物群落类型相一致。大型底栖动物分带受红树植物群落类型影响的主要原因是不同红树植物群落间的群落特征、沉积物性质和所处潮位线存在差异。     

The current status of mangroves along the Kenyan coast: a case study of Mida Creek mangroves based on remote sensing

Mangroves form a unique ecosystem of limited extent covering an area of about 53 000 ha along the Kenyan coast which need protection from overexploitation. Background information on the areal extent and status of these mangroves is limited and makes their protection and management difficult.A model study has been carried out on the Mida Creek mangroves based on a double sampling approach starting with SPOT multispectral satellite imagery followed by ground checks to provide information on species composition, density and distribution of mangroves. The utilization of mangroves and uses around and within the mangroves were determined.During this study, seven mangrove species were identified in Mida Creek, namely:Avicennia marina, Bruguiera gymnorrhiza, Ceriops tagal, Rhizophora mucronata, Sonneratia alba, Xylocarpus granatum andLumnitzera racemosa. This report briefly outlines the present utilisation of mangrove species. It is recommended that a multidisciplinary management plan be developed in order to conserve and manage the mangroves of Kenya on a sustainable yield basis.     

红树林湿地相手蟹科动物摄食生态研究进展

相手蟹科物种是红树林湿地的主要底栖动物类群,在生态系统中起着重要的作用。我国大陆地区目前已记录的相手蟹科物种数量为12种,低于其它红树林地区(国内常用的采样方法会造成螃蟹物种数量和密度的低估),其中褶痕相手蟹(Sesarma plicata)、无齿相手蟹(S.deaani)和双齿相手蟹(S.bidens)等是常见种。红树植物叶片是相手蟹科动物的主要食物来源,相手蟹科动物通过地表摄食和洞穴贮存的形为消耗了大量的红树植物凋落叶,使这些凋落叶的有机质和营养元素得以保留在生态系统内,在凋落叶的周转和物质归还方面起到重要的作用。它们同时也摄食红树植物的繁殖体并且对不同物种的繁殖体具有摄食偏好,这可能对一些红树物种的植被更新能力和红树植被群落结构产生影响。相手蟹科动物对不同物种和不同状态的红树叶片也存在摄食偏好,通常对腐烂的叶片摄食偏好较强;螃蟹的摄食偏好与叶片的营养成份、粗纤维和单宁含量以及C/N比等性质有关;但在恶劣的野外环境下,螃蟹则会表现出随机性摄食。目前关于相手蟹科动物生态学作用的认识仍不充分,例如它们的种群大小和对凋落物的转化作用等,有待于进一步研究。     

Spatial zonation of macrobenthic fauna in Zhanjiang Mangrove Nature Reserve, Guangdong, China

The spatial zonation of macrobenthic fauna in the core region of Zhanjiang Mangrove Nature Reserve was studied with two transects vertical to the shoreline. The first transect was near Deyao Village where three faunal zones of the mangrove swamp could be divided into the following types from the high tide part to the low tide part: the Assiminea lutea-Uca arcuata-Paracleistostoma crassipilum zone, the Cleistostoma dilatatum-Macrophthalmus erato-Littoraria melanostoma zone, and the Paracleistostoma depressum-Cerithidae cingulata zone. Mollusck and crustacean exhibited the highest individual density in this transect. Mollusck mainly influenced the dynamics of community biomass as well as the species diversity index. In the second transect near Hongzhai Village, the following four faunal zones could be determined: the Littoraria melanostoma-Pseudoringicula sinensis-Ceratonereis burmensis zone, the Assiminea lutea-Cleistostoma dilatatum zone with a dominant species belonging to the Ellobiidae, Upogebia sp.-Paracleistostoma depressum zone, and the Metaplax sheni-Cerithidae cingulata zone. The crustacean showed the highest individual density in this transect. Similar to the Deyao transect, dynamics of community biomass and the species diversity index of the Hongzhai transect were mainly influenced by mollusck. By hierarchical clustering and nonmetric multidimensional scaling, the macrobenthic fauna communities could be divided into three and four groups in the Deyao and Hongzhai transects, respectively. These groups corresponded to different types of vegetation of the mangrove swamp. Taken together, our observations indicated that the spatial zonation of the macrobenthic fauna was mainly affected by the characteristics of the mangrove community, sediment characteristics and the tidal line.     

Spatial zonation of macrobenthic fauna in Zhanjiang Mangrove Nature Reserve, Guangdong, China

The spatial zonation of macrobenthic fauna in the core region of Zhanjiang Mangrove Nature Reserve was studied with two transects vertical to the shoreline. The first transect was near Deyao Village where three faunal zones of the mangrove swamp could be divided into the following types from the high tide part to the low tide part: the Assiminea lutea-Uca arcuata-Paracleistostoma crassipilum zone, the Cleistostoma dilatatum-Macrophthalmus erato-Littoraria melanostoma zone, and the Paracleistostoma depressum-Cerithidae cingulata zone. Mollusck and crustacean exhibited the highest individual density in this transect. Mollusck mainly influenced the dynamics of community biomass as well as the species diversity index. In the second transect near Hongzhai Village, the following four faunal zones could be determined: the Littoraria melanostoma-Pseudoringicula sinensis-Ceratonereis burmensis zone, the Assiminea lutea-Cleistostoma dilatatum zone with a dominant species belonging to the Ellobiidae, Upogebia sp.-Paracleistostoma depressum zone, and the Metaplax sheni-Cerithidae cingulata zone. The crustacean showed the highest individual density in this transect. Similar to the Deyao transect, dynamics of community biomass and the species diversity index of the Hongzhai transect were mainly influenced by mollusck. By hierarchical clustering and nonmetric multidimensional scaling, the macrobenthic fauna communities could be divided into three and four groups in the Deyao and Hongzhai transects, respectively. These groups corresponded to different types of vegetation of the mangrove swamp. Taken together, our observations indicated that the spatial zonation of the macrobenthic fauna was mainly affected by the characteristics of the mangrove community, sediment characteristics and the tidal line.     

Effects of species partition on explanatory variables in direct gradient analysis - a case study from Senegal

Abstract. Species-environment data from Senegal, West Africa, are used to study the effects of partition of a large species data set into subsets corresponding to rare and common species respectively. The original data set contains 129 woody plant species from 909 plots and 60 explanatory variables. By applying Canonical Correspondence Analysis to data subsets, marked differences in the forward-selected variables were detected. The highest resemblance was found between the complete species set and the common species subset. Only one of eight selected variables was common to all species and the rare species groups. These findings were tested with partial ordination, applying the selected variables from the original species group (Vb), as variables and covariables to the analyses of common and rare species. For the common species this application resulted in a constrained ordination with higher eigenvalues as compared to the set of variables selected with reference to the common species group. Using the rare species group, the application of Vb gave a much lower sum of eigenvalues than did the ordination with selected variables based on the rare species group only. Evidently, the set of variables selected on the basis of the rare species data were more significant. Hence, the resulting gradients depend on the frequency of the species. Gradient analysis is apparently only valid for groups of species with closely resembling characteristics. This implies that different functional types of species, with different distributions and abundances, respond individually to environmental variation. Extrapolating deduced gradients from one species group to another maybe risky, particularly when used in vegetation modelling.     

Evaluating,predicting and mapping belowground carbon stores in Kenyan mangroves

Despite covering only approximately 138 000 km², mangroves are globally important carbon sinks with carbon density values three to four times that of terrestrial forests. A key challenge in evaluating the carbon benefits from mangrove forest conservation is the lack of rigorous spatially resolved estimates of mangrove sediment carbon stocks; most mangrove carbon is stored belowground. Previous work has focused on detailed estimations of carbon stores over relatively small areas, which has obvious limitations in terms of generality and scope of application. Most studies have focused only on quantifying the top 1 m of belowground carbon (BGC). Carbon stored at depths beyond 1 m, and the effects of mangrove species, location and environmental context on these stores, are poorly studied. This study investigated these variables at two sites (Gazi and Vanga in the south of Kenya) and used the data to produce a country‐specific BGC predictive model for Kenya and map BGC store estimates throughout Kenya at spatial scales relevant for climate change research, forest management and REDD+ (reduced emissions from deforestation and degradation). The results revealed that mangrove species was the most reliable predictor of BGC; Rhizophora muronata had the highest mean BGC with 1485.5 t C ha^?1. Applying the species‐based predictive model to a base map of species distribution in Kenya for the year 2010 with a 2.5 m² resolution produced an estimate of 69.41 Mt C [±9.15 95% confidence interval (C.I.)] for BGC in Kenyan mangroves. When applied to a 1992 mangrove distribution map, the BGC estimate was 75.65 Mt C (±12.21 95% C.I.), an 8.3% loss in BGC stores between 1992 and 2010 in Kenya. The country‐level mangrove map provides a valuable tool for assessing carbon stocks and visualizing the distribution of BGC. Estimates at the 2.5 m² resolution provide sufficient details for highlighting and prioritizing areas for mangrove conservation and restoration.     

基于MAXENT模型评估北部湾潮间带中国鲎和圆尾鲎稚鲎的潜在地理分布及种群保育对策

鲎具有极高的经济价值和科研意义。近年来由于过度捕捞和栖息地受损等原因,亚洲鲎种群数量正急剧下降。鲎漫长的生命周期使得鲎资源的保护和增殖迫在眉睫。生态位模型已经广泛应用于物种的潜在地理分布预测。基于实地调研数据和公开发表的北部湾中国海域中国鲎和圆尾鲎地理分布数据,运用MAXENT模型得到中国鲎和圆尾鲎在广西北部湾(中国部分)的栖息地适宜度指数(Habitat suitability index, HSI),确定了这两种稚鲎在北部湾中国海域潜在适生区。模型分析结果表明,潮间带坡度和地形指数是影响中国鲎分布的主要环境因子,而潮间带底质的有机物含量和植被指数是影响圆尾鲎分布的主要环境因子,根据研究结果建议在两种稚鲎适生区建立保护区,进行人工放流稚鲎,加强对海草和红树林的生态建设,进而促进鲎资源种群恢复和发展。     

Early primary succession on Mount St. Helens,Washington, USA

Abstract. The north slope of Mount St. Helens was sampled with 141 circular 100-m² plots to describe vegetation and environmental patterns 13 yr after the 1980 eruption. At least 114 vascular plant taxa were encountered. We recognized four habitat types: Refugia, Pumice barrens, Pyroclastic surfaces and Drainages. A fifth category, Lupine patches, includes samples on primary surfaces that were rapidly colonized. Refugia provided small enclaves where underground portions of several species survived the eruption. They retained an inconsistent array of forest understory species and contained 86 species (mean = 20.8 per plot). Refugia are dominated by woody species such as Penstemon cardwellii, Rubus spp., Ribes spp. and Alnus sinuata, with herbs such as Agrostis diegoensis, Luzula parviflora and Anaphalis margaritacea. Anaphalis represents a suite of species that invaded Refugia after the eruption. Diversity (N₂ and H′) is significantly greater in Refugia than in any other habitat. No plants survived on primary sites, which remain sparsely vegetated and dominated by readily dispersed taxa. Total richness ranges from 36 species (9.9 per plot) on pyroclastic surfaces, through 42 species (11.2 per plot) in drainages, to 66 (11.7 per plot) on Pumice barrens. H′ and N₂ of the three habitats do not differ significantly. Lupine-dominated vegetation occurs sporadically in Pyroclastic and drainage habitats. Lupine patches are characterized by high Lupinus cover and a suite of invaders. These sites have high cover and 52 species (12.6 per plot). H′ and N₂ scores were significantly lower than any other habitat due to strong lupine dominance. Canonical Correspondence Analysis showed that site history and slope contributed most to species composition. Geographic effects accounted for 10 25 % of the explained species-environment relationship. Forest understory species have migrated only short distances and have made negligible contributions to vegetation development. A few species common in Refugia, including Agrostis diegoensis and Carex mertensii, have invaded barren surfaces, but most have not. Refugia also have been invaded by open site species abundant on the Pumice Plain. The heterogeneity of plots within habitat types and small statistical linkage of vegetation to environmental and spatial factors suggests that stochastic events have played a leading role in early primary succession.     

Isolation and characterization of 11 microsatellite loci in the mangrove crab, Ucides cordatus (Ocypodidae: Ucidinae)

Eleven polymorphic microsatellite loci were described for the mangrove crab, Ucides cordatus, an important fishery resource on the Brazilian coast. The number of alleles observed at each locus varied between eight and 23. Observed and expected mean heterozygosities were 0.791 and 0.893 respectively. Amplification of all loci was highly successful, under the same polymerase chain reaction conditions. With the exception of P2D3, all loci adhered to the assumptions of the Hardy-Weinberg equilibrium and did not present deviations reflecting linkage disequilibrium. Given this, these markers will be extremely useful in future management programmes for U. cordatus stocks.     

Habitat and zonation patterns of Littoraria species (Gastropoda: Littorinidae) in Indo-Pacific mangrove forests

The zonation of 15 species of Littoraria in the scabra group is described, using a transect method, at 13 mangrove localities in Australia, Thailand, Malaysia and Hawaii. At these localities the littorinids occurred only on trees, and showed both vertical and horizontal patterns of zonation, with broad overlaps between co-occurring species. It is suggested that vertical distribution is determined mainly by behavioural responses, while the landward limits of horizontal distribution may be set by physiological tolerance. Several species occurred predominantly on either leaf or bark substrates, but no consistent associations with tree species were found. On the basis of local distribution patterns, Littoraria species can be classified as continental or oceanic in character. Oceanic species may be less tolerant of sediment in the water or on the substrate.     

Defining phytoclimatic units in Galicia,Spain, by means of multivariate methods

Abstract. Floristic and climate data from 150 plots in 25 sites in Galicia, Spain, were analysed to test the hypothesis that climate is the major factor governing the distribution of woody plant species. TWINSPAN classification, Detrended Correspondence Analysis and Canonical Correspondence Analysis were applied in successive stages of the data analysis to describe vegetational variation in relation to climatic gradients. Six groups of species were defined, two clearly oceanic (Maritime and Cool Maritime), one mediterranean maritime, and three mediterranean (Cold Mediterranean, Cool Mediterranean and Temperate Mediterranean). An aridity gradient was revealed as the primary factor regulating the distribution of the species considered. This main gradient reflects the transition between the Eurosiberian and Mediterranean bio-geographic regions. The gradient can be characterized by means of the Vernet bioclimatic index. A value ≥ 4 for this index can be taken to define the mediterranean zone in our study area. The mean minimum temperature in the coldest month was the second most influential climatic variable. Partial ordination analysis revealed that the residual variation was insignificant and that the observed variation in vegetation can be fully accounted for by climatic variables.     

Zonation of mangrove flora and fauna in a subtropical estuarine wetland based on surface elevation

In the context of sea‐level rise (SLR), an understanding of the spatial distributions of mangrove flora and fauna is required for effective ecosystem management and conservation. These distributions are greatly affected by tidal inundation, and surface elevation is a reliable quantitative indicator of the effects of tidal inundation. Most recent studies have focused exclusively on the quantitative relationships between mangrove‐plant zonation and surface elevation, neglecting mangrove fauna. Here, we measured surface elevation along six transects through the mangrove forests of a subtropical estuarine wetland in Zhenzhu Bay (Guangxi, China), using a real‐time kinematic global positioning system. We identified the mangrove plants along each transect and investigated the spatial distributions of arboreal, epifaunal, and infaunal molluscs, as well as infaunal crabs, using traditional quadrats. Our results indicated that almost all mangrove forests in the bay were distributed within the 400–750 m intertidal zone, between the local mean sea level and mean high water (119 cm above mean sea level). Mangrove plants exhibited obvious zonation patterns, and different species tended to inhabit different niches along the elevation gradient: Aegiceras corniculatum dominated in seaward locations while Lumnitzera racemosa dominated in landward areas. Mangrove molluscs also showed distinct patterns of spatial zonation related to surface elevation, independent of life‐form and season. The spatial distributions of some molluscs were correlated to the relative abundances of certain mangrove plants. In contrast, the spatial distributions of crabs were not related to surface elevation. To the best of our knowledge, this is the first study to explicitly quantify the influences of surface elevation on the spatial distributions of mangrove fauna. This characterization of the vertical ranges of various flora and fauna in mangrove forests provides a basic framework for future studies aimed at predicting changes in the structure and functions of mangrove forests in response to SLR.     

An improved method for pollen release from anther: a case study with mangroves

The estimation of pollen production is widely used in pollination and reproductive ecology, aerobiology and pollen-vegetation relationship studies. Pollen release is the key step in estimating pollen production and therefore, the technique used to release pollen is critical. Three methods, the drying method (DM), mechanical method (MM) and chemical method (CM), are used to determine the amount of pollen released from anthers. Few studies have compared the results obtained from each method, making it difficult to determine which method is most appropriate in a given situation. In this study, we compared existing methods with a new method that increases the amount of pollen released from anthers. Eight species of mangrove trees from the Neilingding-Futian National Nature Reserve were selected for study. We combined the MM and CM to produce a new method (the ultrasonic method, UM). To determine the best ultrasonic treatment time using the UM, different durations were tested and the various responses were analysed. The relationships between pollen rupture and the ultrasonic treatment time, pollen size, exine thickness and aperture size were analysed. Finally, four methods for pollen release from anthers were compared. The results indicated that the UM could be an efficient method to release pollen from the anther. To avoid pollen rupture, ultrasonic treatment times in the UM should be less than 30 s. The pollen rupture rate was significantly correlated with the ultrasonic treatment time (r = 0.618, p < 0.001) and the aperture size (r = 0.248, p = 0.036). This comparative experiment indicated that the UM can generate a greater pollen yield than other methods while causing less pollen rupture than the MM. Therefore, the UM may be suitable for more plant species and more accurate for pollen production estimates than the existing three methods, particularly when estimating pollen production in all community plants.     

The natural diet of the mud crab Scylla olivacea (Herbst, 1896) in Pichavaram mangroves,India

Food and feeding habits of mud crab Scylla olivacea (Herbst, 1896) in Pichavaram mangroves was investigated quantitatively and qualitatively for a period of two years from June 2010 to May 2012. Gut contents from 1737 specimens comprising 843 males and 894 females in the size range between 45 mm and 148 mm were examined. Crustaceans form the predominant food item in a majority of size groups in terms of percentage wet weight and frequency of occurrence, while molluscs showed a preference in few size groups. The other dietary items includes fishes, detritus, mud and sand and miscellaneous. Gut content analysis revealed no significant variation between the quantities of food consumed by both sexes. Feeding intensity was higher in juveniles and subadults of both sexes than that of adults, revealing a greater preference to feed on fast moving prey such as crustaceans and fishes. The results of the present study indicate that S. olivacea in Pichavaram mangroves exhibited a clear preference for crustaceans.     

Testing patterns of zonation in mangroves: scale dependence and environmental correlates in the Sundarbans of Bangladesh

Summary 1  Associations between abiotic variables and patterns of species distribution and abundance are a major preoccupation of community ecologists. In many habitats, this association is manifest in discrete zones of vegetation.
2  We used statistical methods to examine tree species distribution patterns in relatively undisturbed regions of the Sundarbans of Bangladesh. We tested the hypothesis that mangroves occur in discrete zones with respect to elevation. These data were gathered with explicit attention to local and regional differences in edaphic characteristics so that species-environment relationships could be analysed at several spatial scales.
3  Correlations were also assessed between mangrove species composition and edaphic variables that co-vary with elevation, i.e. salinity, field capacity, cation exchange capacity, percentage silt, and mangrove physiognomic category (slope, basin, levee and flat).
4  Quantitative statistical analysis using randomization techniques failed to detect species zonation along any of 33 individual 200-m transects, within 1-km² blocks, or within 1200-km² regions.
5  Canonical correspondence analysis relating edaphic variables to species distributions accounted for a total of only 24% of the variance in species composition.
6  Our data suggest that the absence of zonation in the Bangladesh Sundarbans reflects the underlying biology of the system and is not an artefact of long-term human disturbance.     

Invaders' control on post-disturbance succession in coastal mangroves

Aims In recent years, coastal mangroves have been frequently affected by large disturbances (cyclones, hurricanes, flooding and tsunamis) and post-disturbance vegetation is often dominated by small stature mangrove, mangrove-associate and non-mangrove species potentially affecting ecosystem functioning. Knowledge on the processes of mangrove vegetation development and recovery (succession) following normal and large disturbances will benefit practitioners in designing robust ecosystem management/restoration plans. Here we propose a conceptual model of disturbance-mediated succession in mangroves.Methods Based on field observations and species' life history traits, we develop conceptual models of mangrove succession under normal disturbance regime and recently experienced increased frequency of large disturbances. We evaluate our conceptual models by conducting a scenario testing experiment.Important findings We suggest two predominant processes affecting mangrove succession after disturbance: propagule limitation due to damage of seed producing mature trees and dispersal barrier resulting from biological invasion associated with large disturbance. We argue that large disturbances affect mature trees more than the small-stature non-tree (shrubs, herbs and climbers) species creating a larger propagule shortage for mangrove tree species than non-tree species. Secondly, large disturbances facilitate invasion of free-floating aquatics, which may interfere with the flow-facilitated propagule dispersal and seedling establishment of mangrove species. In a scenario testing experiment, we have shown that similar levels of disturbance impact vegetation development and recovery differently depending on the presence or absence of invasive species. We conclude that since biological invasion is one of the major drivers of post-disturbance mangrove succession, the dimension of biological invasion should be included in prediction, management and restoration of mangrove forests.     

世界蓑藓属植物分布式样及其系统演化和生物地理学意义

蓑藓属（Macromitrium）是苔藓植物分类、生态学研究及生物多样性保护的重要类群。以“Index Muscorum”中的14个藓类植物地理分布单位为分析区域,基于标本信息和相关文献,在分类修订的基础上,统计了世界蓑藓属274种植物在14个地理单位的分布数据,基于这些数据,应用聚类分析和除趋势对应分析法,分别得到了14个地理单位的聚类图和三维空间图,直观展示了世界蓑藓属植物的地理分布格局。发现蓑藓属植物区系在东亚（As2）、大洋洲（Oc）、南亚和东南亚（As3,As4）、非洲（Afr2,Afr3,Afr4）、中美洲-南美洲（Am2,Am3,Am4,Am5）、澳洲（Austr1,Austr2）存在区域分化。热带亚洲和热带美洲是世界蓑藓属植物的多样化中心。除长柄蓑藓（M.microstomum（Hook.&Grev.）Schwägr.）在14个地理单位均有分布外,大部分种类分布限于少数或仅一个地理单位。蓑藓属植物在东亚、热带亚洲、热带美洲和澳洲不仅种类存在明显分化,而且形态性状也有区域特点。根据蓑藓属植物的现代分布式样,探讨了其系统演化和生物地理学意义。