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。     

The interaction of disturbances and small mammal community dynamics in a lowland forest in Belize

1. Three floods (July 2000, August 2002, September 2003) and a hurricane (October 2001) that occurred in a lowland forest in the southern Maya Mountains of Belize presented an opportunity to evaluate the influence of these disturbances on the structure of a small mammal assemblage. 2. Four terrestrial and four primarily scansorial/arboreal species were trapped July 2000-March 2005 in six grids over 14 irregularly spaced trapping periods. 3. Community dynamics were characterized more by changes in species composition than changes in diversity. The dynamics were driven by species-specific variation in abundance, with changes in composition generally, but not exclusively, due to the occurrence or disappearance of species at low abundance. Despite the disturbances, species richness remained relatively constant. Evenness within the assemblage was consistently low, primarily as a result of dominance by one species, Heteromys desmarestianus. 4. Effects of flooding on community structure were direct but relatively brief (< 1 year), and varied with the duration and intensity of flooding. Effects from the hurricane were indirect but long-lasting and strongly related to severely reduced food resources. 5. This study suggests that long-term dynamics in the structure of many animal communities in the tropics often results from interactions between direct and indirect effects of disturbance. It also suggests that community resistance will depend on variation in disturbance type and regime, but resilience will be determined by the life-history characteristics of each species.     

Is a community still a community? Reviewing definitions of key terms in community ecology

Community ecology is an inherently complicated field, confounded by the conflicting use of fundamental terms. Nearly two decades ago, Fauth et al. (1996) demonstrated that imprecise language led to the virtual synonymy of important terms and so attempted to clearly define four keywords in community ecology; “community,” “assemblage,” “guild,” and “ensemble”. We revisit Fauth et al.'s conclusion and discuss how the use of these terms has changed over time since their review. An updated analysis of term definition from a selection of popular ecological textbooks suggests that definitions have drifted away from those encountered pre‐1996, and slightly disagreed with results from a survey of 100 ecology professionals (comprising of academic professors, nonacademic PhDs, graduate and undergraduate biology students). Results suggest that confusion about these terms is still widespread in ecology. We conclude with clear suggestions for definitions of each term to be adopted hereafter to provide greater cohesion among research groups.     

Reproductive allocation of Solidago canadensis L. plays a key role in its invasiveness across a gradient of invasion degrees

Reproductive allocation (RA) plays a vital role in the development of ecological strategies during the life cycle of plant species. Invasive alien plants (IAP) may exist at various invasion degrees across a gradient of the colonization process with several grades of relative abundances in the occupied environments. The progressive variation in the invasion degree of IAP has the potential to modify their RA strategy. This study purposes of estimating the RA strategy of the IAP Solidago canadensis L. and the correlations among RA of S. canadensis, the invasion intensity of S. canadensis, the invasiveness of S. canadensis, and the community invasibility across a gradient of invasion degrees by using the field sampling experiment. The height and relative abundance of S. canadensis did not remarkably affect its RA. The RA of S. canadensis was positively related to its reproductive biomass and total biomass. The key reason may be that plant individuals with higher total biomass can allocate more resources into sexual reproduction. The RA of S. canadensis was positively related to its invasiveness. Thus, the RA of S. canadensis may be crucial to its invasiveness.     

Effects of flooding on a wetland bird community

The Lake Izunuma–Uchinuma was extensively flooded in 1998 and vast areas (approximately 200 ha) of rice fields were submerged for the first time since the land was reclaimed in 1963. When the numbers of birds in 1998 were compared with those in normal years (1995–1997), the numbers of black-crowned night herons (Nycticorax nycticorax L.), cattle egrets (Bubulcus ibis L.) and black kites (Milvus migrans Boddaert) increased during the flooding, and the numbers of ducks, especially dabbling ducks (seven species of 11 Anas spp.) were high even after the flooding, while the numbers of the little grebe Tachybaputus ruficollis Pallas were diminished by the flooding.     

Response of fungal, bacterial and ureolytic communities to synthetic sheep urine deposition in a grassland soil

In grazed pastures, soil pH is raised in urine patches, causing dissolution of organic carbon and increased ammonium and nitrate concentrations, with potential effects on the structure and functioning of soil microbial communities. Here we examined the effects of synthetic sheep urine (SU) in a field study on dominant soil bacterial and fungal communities associated with bulk soil and plant roots (rhizoplane), using culture-independent methods and a new approach to investigate the ureolytic community. A differential response of bacteria and fungal communities to SU treatment was observed. The bacterial community showed a clear shift in composition after SU treatment, which was more pronounced in bulk soil than on the rhizoplane. The fungal community did not respond to SU treatment; instead, it was more affected by the time of sampling. Redundancy analysis of data indicated that the variation in the bacterial community was related to change in soil pH, while fungal community was more responsive to dissolution of organic carbon. Like the universal bacterial community, the ureolytic community was influenced by the SU treatment. However, different taxa within the ureolytic bacterial community responded differentially to the treatment. The ureolytic community comprised of members from a range of phylogenetically different taxa and could be used to measure the effect of environmental perturbations on the functional diversity of natural ecosystems.     

Exploitation and community engagement: Can Community Advisory Boards successfully assume a role minimising exploitation in international research?

It has been suggested that community advisory boards (CABs) can play a role in minimising exploitation in international research. To get a better idea of what this requires and whether it might be achievable, the paper first describes core elements that we suggest must be in place for a CAB to reduce the potential for exploitation. The paper then examines a CAB established by the Shoklo Malaria Research Unit under conditions common in resource‐poor settings – namely, where individuals join with a very limited understanding of disease and medical research and where an existing organisational structure is not relied upon to serve as the CAB. Using the Tak Province Border Community Ethics Advisory Board (T‐CAB) as a case study, we assess the extent to which it might be able to take on a role minimising exploitation were it to decide to do so. We investigate whether, after two years in operation, T‐CAB is capable of assessing clinical trials for exploitative features and addressing those found to have them. The findings show that, although T‐CAB members have gained knowledge and developed capacities that are foundational for one‐day taking on a role to reduce exploitation, their ability to critically evaluate studies for the presence of exploitative elements has not yet been strongly demonstrated. In light of this example, we argue that CABs may not be able to perform such a role for a number of years after initial formation, making it an unsuitable responsibility for many short‐term CABs.     

Towards a morphological metric of assemblage dynamics in the fossil record: a test case using planktonic foraminifera

With a glance, even the novice naturalist can tell you something about the ecology of a given ecosystem. This is because the morphology of individuals reflects their evolutionary history and ecology, and imparts a distinct ‘look’ to communities—making it possible to immediately discern between deserts and forests, or coral reefs and abyssal plains. Once quantified, morphology can provide a common metric for characterizing communities across space and time and, if measured rapidly, serve as a powerful tool for quantifying biotic dynamics. Here, we present and test a new high-throughput approach for analysing community shape in the fossil record using semi-three-dimensional (3D) morphometrics from vertically stacked images (light microscopic or photogrammetric). We assess the potential informativeness of community morphology in a first analysis of the relationship between 3D morphology, ecology and phylogeny in 16 extant species of planktonic foraminifera—an abundant group in the marine fossil record—and in a preliminary comparison of four assemblages from the North Atlantic. In the species examined, phylogenetic relatedness was most closely correlated with ecology, with all three ecological traits examined (depth habitat, symbiont ecology and biogeography) showing significant phylogenetic signal. By contrast, morphological trees (based on 3D shape similarity) were relatively distantly related to both ecology and phylogeny. Although improvements are needed to realize the full utility of community morphometrics, our approach already provides robust volumetric measurements of assemblage size, a key ecological characteristic.     

Denitrification by the sessile microbial community of a polluted river

Denitrification by the sessile microbial community of the River Tamagawa was studied in laboratory experiments. Inorganic nitrogen loss was observed when river water was incubated with sessile microbial community of the river in a continuously circulating system. It was confirmed by the ¹⁵N tracer technique that both sessile microbial communities of unpolluted and polluted areas had denitrifying activity, even though they were incubated in oxygenated river water. The denitrification rate of the sessile microbial community taken from a polluted area, measured by the ¹⁵N tracer technique, was 8–16 mg N/m²/day in October and December, 1977, and it was enhanced 10-fold by raising the water temperature from 14 to 30° C. Denitrification in the river was also suggested by determining the N₂: Ar ratio of gases evolved from the river bed.     

生态社区评价指标体系研究进展

生态社区建设融合了建筑学、生态学、社会学等多学科原理,充分体现了人与自然和谐的理念,是符合可持续发展理念的社区发展模式。生态社区评价指标体系在一定的一级指标框架下,采用定性或定量的评价指标,评判社区的可持续发展水平。对生态社区的概念和内涵、形成与发展历程、国内外生态社区相关评价指标体系进行总结和归纳,在此基础上综述了生态社区评价指标体系的研究进展,包括评价主体、一级指标框架的构建、二三级指标使用的频度分析及指标权重的确定方法。最后总结分析了生态社区指标体系研究中对外环境关联、动态发展、参与性与适应性等方面的不足,提出将复杂性理论、生命周期分析方法和生态足迹分析引入生态社区评价指标体系的研究,以提高指标体系的系统性、科学性和参与性。     

亚热带大型水库—新丰江水库的浮游生物群落特征

于2000年丰水期和枯水期,调查了新丰江水库的浮游生物群落结构。新丰江水库处于贫营养状态,浮游生物密度和生物量均较低。浮游植物34种,丰水期以蓝、绿藻为主,分别占总数量的31.7%和26.8%,蓝藻、绿藻细胞微小,chl-a量未占优势;枯水期硅藻为优势种群,占63.9%。浮游动物22种,丰水期轮虫为主,占65.3%,枯水期桡足类占81%,丰水期动物密度较高,但丰水期以轮虫如螺形龟甲轮虫为主,枯水期以无节幼体、桡足幼体及广布中剑水蚤居多,因此枯水期生物量高于丰水期。     

A comparison of the responses of two microcosm designs to a toxic input of copper

Two microcosm designs were compared for their sensitivity to toxic concentrations of copper. One design simulated a littoral zone, including macrophytes, sediment, and associated organisms. The other design used a periphyton community collected on polyurethane foam artificial substrata. Microcosms were dosed with copper sulfate (0–300 µg Cu 1^–1, nominal concentrations) and monitored for changes in several structural and process variables. Coefficients of variation of responses measured from the littoral microcosms were greater than from responses measured from the artificial-substrata microcosms. Effects were detected more frequently at lower concentrations of copper in the artificial-substrata microcosms than in the littoral microcosms. Lowest observable effect concentrations (LOECs) for measures of community structure ranged from 20.2–42.8 µg Cu 1^–1 in the artificial-substrata microcosms and from 24.0–98.5 µg Cu 1^–1 in the littoral microcosms. LOECs for measures of community process ranged from 42.8–310.3 µg 1^–1 in the artificial substrata microcosms. Significant differences from controls for community process were detected only at 304.7 µg Cu 1^–1 in the littoral microcosms. While there were differences between the two microcosm designs in the concentrations of copper that resulted in adverse effects, response trends were similar. Often, dose-response relationships between variables and copper concentrations were not log-linear, but showed stimulations at intermediate concentrations of copper (10–100 µg 1^–1, nominal concentrations). The choice of microcosm design should be dependent on the particular research question, as the designs differ in complexity and in the ease of construction and maintenance.     

Ecological indicators for assessing ecological success of forest restoration: a world review

Restoration is increasingly being used to reverse degradation and destruction of forest ecosystems. With increasing investment in restoration, there is an urgent need to develop effective programs to assess treatment efficacy and effects. We conducted a global review of forest restoration assessments, in order to identify geographic trends in the locations where assessments have been implemented and the specific ecological attributes (ecosystem composition, structure, and function) and indicators being used to measure effects. We found that the number of forest restoration assessments varied by region and was not related to degree of degradation or restoration need. Some regions, like Africa, which have experienced high rates of forest loss and degradation, had few assessments. The majority (43%) of assessments included indicators for only two of three key ecological attributes (composition‐structure or composition‐function) and assessments on average used fewer than three indicators per attribute. The most commonly employed indicators for composition were richness and abundance of plant species and for structure were height and diameter of trees, variables that are generally relatively easy to measure. The use of functional indicators has been increasing over time and they are now more commonly used than structural indicators. The most common functional indicators were soil functions. Most investigators evaluated treatment effects for 6–10 years after implementation. Our findings related to gaps in analysis of ecological indicators can serve as a guide for developing monitoring and assessment protocols for current global forest restoration initiatives by 2020–2030.     

Distinct successional patterns and processes of free-living and particle-attached bacterial communities throughout a phytoplankton bloom

1. Understanding the successional patterns of microbial communities during a phytoplankton bloom is crucial for predicting the compositional and functional stability of lake ecosystems in response to the disturbance of a bloom. Previous studies on bacterial communities associated with blooms have rarely studied the dynamics of these communities. The successional patterns of bacterial communities within different micro-habitats (i.e. water column versus particles) and mechanisms that shape these communities that differ in composition and structure remain unclear.
2. We selected a eutrophic urban lake to investigate the succession of bacterial communities during a bloom. We divided the bacterial communities into free-living (FL) and particle-attached (PA) groups based on their different lifestyles. The amplicon-based 16S rRNA gene high-throughput sequencing technology was used to obtain bacterial community composition and phylogenetic structure.
3. Our study showed distinct successional patterns between FL and PA bacterial communities, and the two bacterial lifestyles showed different responses and resilience to the bloom, in terms of diversity and relative abundance of bacterial taxa. Alpha-diversity of the PA bacterial community decreased during the bloom, whereas that of the FL bacterial community increased. More taxa in the FL bacterial community showed resilience after the disturbance than in the PA bacterial community.
4. The influence of phytoplankton blooms on the assembly of the bacterial community can be viewed as niche selection that led to the decrease in the relative importance of stochastic processes in shaping both FL and PA bacterial communities. This study shows the ecological significance of the bacterial community response to bloom events in lakes. It also shows that assembly processes differ for bacterial communities that have different lifestyles in lake ecosystems disturbed by phytoplankton blooms.

     

Temporal Dynamics of River Biofilm in Constant Flows: A Case Study in a Riverside Laboratory Flume

A 15‐week experiment was performed in a riverside laboratory flume (with diverted river water) to check variations of river biofilm structure (biomass, algal and bacterial compositions) and function (community gross primary production GPP and respiration) under constant flow while water quality went through natural temporal variations. One major suspended matter pulse coinciding with one river flood was recorded after 10 weeks of experiment. Epilithic biofilm first exhibited a 10‐week typical pattern of biomass accrual reaching 33 g ash‐free dry matter (AFDM) m^–2 and 487 mg chlorophyll‐a m^–2 and then, experienced a shift to dominance of loss processes (loss of 60% AFDM and 80% chlorophyll‐a) coinciding with the main suspended matter pulse. Algal diversity remained low and constant during the experiment: Fragilaria capucina and Encyonema minutum always contribute over 80% of cell counts. DGGE banding patterns discriminated between two groups that corresponded to samples before and after biomass loss, indicating major changes in the bacterial community composition. GPP/R remained high during the experiment, suggesting that photoautotrophic metabolism prevailed and detachment was not autogenic (i.e., due to algal senescence or driven by heterotrophic processes within the biofilm). Observational results suggested that silt deposition into the biofilm matrix could have triggered biomass loss. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The influence of biomanipulation on fish community development in a southeastern United States cooling reservoir

L Lake, a reactor cooling reservoir in South Carolina, USA was managed after filling to promote the development of healthy ecological communities similar to those in mature regional cooling reservoirs. Two types of biomanipulation were undertaken to achieve this goal, the introduction of typical southeastern US reservoir fishes (bluegill and largemouth bass) and artificial planting of native aquatic macrophytes. Fish assemblages were monitored by electrofishing from reservoir filling in 1986 until 1998. Multivariate analysis divided the fish samples into five sequential periods resulting from species replacements and additions. Small species that colonized L Lake from a feeder stream predominated in the first period but were mostly eliminated, as bluegill, largemouth bass, and other lentic species increased in the second period. A rapid increase in threadfin shad abundance characterized the third period, and small littoral zone and phytophilous fishes increased during the fourth and fifth periods coincident with the proliferation of aquatic macrophytes. Analysis of Bray-Curtis similarities and the species accumulation rate indicated that the rate of fish community change decreased with time and that fish community structure changed little during the last several years of the study. By the end of the study, community structure was similar to that in a nearby cooling reservoir that supported diverse and resilient biota. Biomanipulation contributed to the rapid establishment of lentic species and later increases in small littoral and phytophilous species suggesting that biomanipulation may be useful in accelerating fish community development in new cooling reservoirs.     

Community and population-level responses to disturbance in a sandflat community

The responses of soft sediment infauna were investigated in an intertidal sandflat to determine patterns of recolonization and succession at the community and population level. Experimental disturbance plots, 1 m², were initiated in August and sampled for 4.5 months along with ambient sediments. Sediment grain-size was used as a general indicator of the physical state of the disturbance patches, and grain-size distributions among disturbance and ambient patches became similar after ∼2.5 months. Recolonization varied among the dominant infaunal taxa. Densities of infauna that were most abundant in the habitat, primarily syllid polychaetes, did not recover to ambient levels until 3-4 months after disturbance, when ambient densities were falling to winter lows. Multivariate analysis indicated that community recovery occurred by the end of the study period after 4.5 months. Although community structure recovered by the end of the study, the population structure of the dominant species Parapionosyllis longicirrata remained significantly different among ambient and disturbed patches. On all sampling dates except one, disturbance patches had a higher number of larger individuals than ambient sediments. Previous studies have shown that bedload transport of juveniles and adults, and other processes, can cause recolonization to be relatively rapid on intertidal sandflats. However, our results indicate that recovery times may be on the order of months at large disturbance sizes. Therefore, rapid responses may occur primarily in the case of small-scale (<1 m²) disturbance patches. Secondly, recovery at the community level does not necessarily mean that population-level characteristics of species comprising the community have recovered. Population-level differences may be longer lasting than indicated by community level indicators of recovery.