Community structure of the benthos in Scottish sea-lochs. III. Further studies on patchiness

Large-scale patchiness in the distribution of the benthic fauna was investigated in Loch Etive (Scottish west coast) by two series of van Veen grab hauls. Each series was taken along a traverse across the width of the loch, with sampling points about 100 m apart. One sample series was taken on sandy mud and the other, at a greater depth, on soft mud. Two approaches in data processing were applied: (1) The variance: mean ratio and the Morisita I tests for significant aggregation were applied to the species abundances in the sample series; (2) 3 measures of sample homogeneity, each involving the calculation of an index of faunal similarity, were applied to the separate samples. The results, however, could not show significant differences between the two series of samples. These findings were compared to results obtained from (a) a previous study, where differences in patchiness between areas were shown for a smaller scale of sampling design in Loch Etive and neighbouring areas, and to which the I method is also applied here; and (b) the results of applying the variance: mean ratio and I tests to data published by Holme (1953). The present results indicate greater aggregation at the present scale of sampling than for the previous, smaller scale of sampling, or for the comparable scale of Holme's sampling. The degree of concordance shown by the values of I for the circular-design sampling to the values of the 3 measures of patchiness applied previously, and to the means of the species abundances, was measured by Spearman's rank correlation coefficient. The results clearly demonstrated the I values, unlike the others measured, to be almost completely independent of the mean. It was concluded that, for comparing the pattern from benthic samples using standard-size bottom samplers, where the mean may vary widely between each set of samples, the I method is probably most useful.     

Community structure of the benthos in Scottish Sea-lochs. IV. Multivariate spatial pattern

Most studies of spatial patterns of invertebrates in soft sediments have concentrated on populations of individual species. Those that examined patterns in communities have tended to employ categorical analytical techniques. Using macrofaunal abundance data from van Veen grab samples collected 20 to 100 m apart in known spatial arrangements from Scottish sea-lochs, the relationships between patterns in macrobenthic species composition and distances between samples were explored using matrix correlations in a non-parametric framework. Using a simple definition of spatial structure, i.e. that intersample distances are monotonically correlated with intersample species-similarity, spatial structure at each of seven stations was assessed using non-parametric Mantel tests based on rank-correlations. Changes in community structure were positively correlated with distance at all sites in Loch Etive, on both current-swept muddy sands and soft deep muds. Different components of the macrobenthos contributed to spatial pattern at each site. Simple spatial structure was also detectable at a muddy-sand site in Loch Creran, but neither on soft mud, nor at the soft mud site in the Firth of Lorne. The concept of rank-correlograms was introduced. These were used to examine the extent and form of spatial structure in different components of the macrobenthos at each site. Relationships between similarity and distance were neither simple nor consistent. Results were compared to previous studies which used the same data, and it was concluded that studies carried out at a particular scale, or on a particular component of the benthos, are unlikely to be successful in predicting spatial relationships at other scales or for other components of the benthos. Correlational rather than categorical analyses are recommended for exploratory studies of spatial relationships in the benthos. Analyses of the spatial structure at these seven sea-loch sites suggests that by ensuring that samples are at least 40 m apart an investigator is unlikely to underestimate variability or otherwise invalidate statistical analyses based on the use of the samples as replicates. Spacing samples up to 100 m apart may increase variability estimates, further reducing the chance of concluding that a difference exists when one does not. Received: 4 May 1999 / Accepted: 8 March 2000     

Infaunal benthos of a natural petroleum seep: Study of community structure

At 8 wk intervals, from December 1975 through March 1978, we took a census of the infaunal benthic invertebrates at a natural petroleum seep near Santa Barbara, California, USA and at an area nearby where no fresh petroleum occurred in the sediments. Both sites had in common 72% of the populations representing over 90% of the individuals, strongly suggesting that the two sites are part of the same community. At the petroleum seep there were higher densities of individuals in many populations (60%), but no dramatic difference in diversity (Shannon-Wiener or dominance-diversity). The seep populations tended to be more variable from one sampling period to the next, possibly due, at least in part, to large larval settlements there. The most abundant populations at the seep site were dominated by deposit feeders (14 of the 15 species considered), especially oligochaetes which are extremely rare at the comparison site. The discussion includes a hypothesis of trophic enrichment of the seep populations by bacterial growth stimulated by fresh petroleum.     

Spatial pattern and ecological process in the coffee agroforestry system

The coffee agroforestry system provides an ideal platform for the study of spatial ecology. The uniform pattern of the coffee plants and shade trees allows for the study of pattern generation through intrinsic biological forces rather than extrinsic habitat patchiness. Detailed studies, focusing on a key mutualism between an ant (Azteca instabilis) and a scale insect (Coccus viridis), conducted in a 45-ha plot in a coffee agroforestry system have provided insights into (1) the quantitative evaluation of spatial pattern of the scale insect Coccus viridis on coffee bushes, (2) the mechanisms for the generation of patterns through the combination of local satellite ant nest formation and regional control from natural enemies, and (3) the consequences of the spatial pattern for the stability of predator-prey (host-parasitoid) systems, for a key coccinelid beetle preying on the scale insects and a phorid fly parasitoid parasitizing the ant.     

底栖动物在水生生态系统健康评价中的作用分析

从生态系统健康的概念入手,通过对生态系统健康评价方法的研究和分析,对底栖动物尤其是大型底柄无脊椎动物在生态系统健康评价中的作用进行了分析和总结.生物监测法和多指标评价法是水生态系统健康评价的主要手段,而利用指示物种、预测模型和底柄生物的完整性指数等多种方法可以对水生态系统健康进行快速和准确的评价.如何完善底栖动物在生态系统健康评价中的作用并综合运用其他评价技术,以及结合评价结果对受损水生态系统进行生态修复和重建将是这一领域未来研究的重点所在.     

重污染河道浮游动物种群的特点

苏州城市河道水情复杂,氮磷浓度较高,属于重污染的滞流水体.通过对试验区南园水系为期1a的调查研究表明:该河段共有浮游动物33种,其中原生动物4种,轮虫类24种,枝角类4种,桡足类1种.各河段浮游动物年平均密度为678 ind·L-1,生物量为56.028 mg·L-1.从种类数来看,轮虫类大于原生动物大于枝角类大于桡足类.从密度看,全年平均以轮虫最多,其次为原生动物,桡足类最少.从生物量看,以枝角类最高,桡足类次之,原生动物最少.从季节变化来看,春夏季较多,秋冬季较少.优势种为轮虫类和枝角类,这些种类极耐有机污染,耐低溶氧.在苏州古城区重污染河道中,浮游动物的总量与水体理化指标及浮游植物的数量等均没有线性相关性(差异显著,p<0.05),这可能与苏州城市河道污染较重有关.城市河道特殊的水域环境决定了浮游动物种群的形成、演变及其发展都有其特殊性.探讨了重污染的城市河道的浮游动物种类组成特点,提出了控制某些优势种群发展的设想,为改善河道水环境提供了理论依据.     

内蒙古皇甫川五分地沟小流域土地覆盖空间格局特征及其持续性分析

基于1979、1987和2002年3个时期的土地覆盖类型图，从斑块面积、形状、空间关系3方面着手。利用斑块面积百分比、面积变异系数、分维数3个景观格局指数对内蒙古皇甫川五分地沟小流域的土地覆盖格局及变化特征进行研究；并以流域为尺度，测算土地覆盖破碎度、多样性指数、分维数、合理性指数4个指标随时间变化的持续性。结果表明：研究区土地覆盖现状呈现各类型相对较均衡的镶嵌状分布格局，土地覆盖类型较稳定，斑块形状较简单，受人类干扰较大。土地覆盖特征指数的持续性分析结果与对应的指标分析结果相吻合。     

内蒙古皇甫川五分地沟小流域土地覆盖空间格局特征及其持续性分析

基于1979、1987和2002年3个时期的土地覆盖类型图,从斑块面积、形状、空间关系3方面着手,利用斑块面积百分比、面积变异系数、分维数3个景观格局指数对内蒙古皇甫川五分地沟小流域的土地覆盖格局及变化特征进行研究;并以流域为尺度,测算土地覆盖破碎度、多样性指数、分维数、合理性指数4个指标随时间变化的持续性。结果表明:研究区土地覆盖现状呈现各类型相对较均衡的镶嵌状分布格局,土地覆盖类型较稳定,斑块形状较简单,受人类干扰较大。土地覆盖特征指数的持续性分析结果与对应的指标分析结果相吻合。     

广东省森林植被碳储量空间分布格局

基于广东省2007年森林资源清查档案数据,采用材积源生物量法,量化广东省森林植被碳储量,研究广东省森林植被碳储量空间分布格局。结果表明,广东省森林植被碳储量为246.35Tg,碳密度为22.96mg·hm-2。受人为干扰和环境因素的影响,广东省森林植被碳储量在不同经济区和流域空间分布格局严重不均。就不同经济区而言,粤北及周边经济区森林植被碳储量最大,达180.22Tg;珠三角经济区次之,为34.60Tg;接着是粤西沿海经济区,为21.49Tg;粤东沿海经济区最小;仅为10.04Tg。在不同流域方面,森林植被碳储量依次为：北江流域〉东江流域〉西江流域〉韩江流域〉其他流域。广东省乔木林碳储量为202.85Tg,以中幼龄林为主,占77.1%;乔木林龄组结构与碳密度近乎成正比关系,存在较大的相关性。     

深圳湾浮游动物的群落结构及季节变化

2008年2月、5月、8月和11月分别对深圳湾浮游动物进行了周年的季节调查,结果共检出浮游动物38种和浮游幼体13类,其中原生动物2种,腔肠动物4种,介形类1种,桡足类22种,软甲类3种,毛颚类3种,被囊类1种,多毛类2种,浮游幼体（包括仔鱼）13类。年均丰度和生物量分别为406.7 ind.m-3和764.0 mg.m-3,高峰均位于夏季,低谷分别位于冬、春季。种类数（包括浮游幼虫）秋季最多为43种,夏季次之为30种,冬季最少仅23种。主要优势种为太平洋纺锤水蚤Acartia pacifica、刺尾纺锤水蚤Acartia spinicauda、短角长腹剑水蚤Oithona brevicornis、双生水母Diphyes chamissonis、卡玛拉水母Malagazzia carolinae、蔓足类幼体和桡足幼体等。多样性指数和均匀度年均值分别为2.568和0.526。回归分析表明浮游动物丰度和生物量与各环境因子之间存在明显的相关性,但有季节变化。     

城乡建设用地景观格局多尺度差异

以郑州市域内1989、2000和2009年的典型城市与农村样地（25 km×25 km）为例,应用空间自相关、半方差、以及九项轨迹方差分析方法,对城市与农村建设用地景观多尺度上的空间格局特征与动态差异进行研究,结果表明,（1）城市建设用地景观聚集强度较高,斑块规模较大,而农村建设用地景观在大部分尺度上呈随机或均匀分布,斑块规模较小。（2）随着尺度的增加,城市及农村建设用地景观分布状态都由聚集向均匀过渡,但前者过渡较为平缓,而后者在小尺度范围（0~2km）变化速度较快,在较大尺度（3~16 km）上其分布状态的波动较小。（3）1989-2009年,城市与农村建设用地景观动态特征有较大差异,并表现出尺度依赖性。城市较小尺度上（0~4 km）建设用地景观的分布状态表现出聚集-分散的趋势,在较大尺度上（8~14 km）表现出分散-聚集的变化趋势。农村小尺度上（0~4 km）建设用地景观的分布状态也表现出聚集-分散的趋势,但大尺度（4~16 km）上状态变化很小且没有规律。     

Spatial pattern of soft-bottom Polychaeta off Nova Scotia,Canada

Patchiness of polychaetes at the micro-scale (i.e. proportional to the sphere of influence of an organism) and macro-scale was investigated in the Northwest Atlantic in 1977 and 1981. Seven box-core samples (each 2 500 cm²) from three sites off Nova Scotia, Canada were completely subsampled as 25 contiguous 100cm² cores and analysed for their polychaete faunas. Dispersion chi-square and autocorrelation analyses were performed on the complete data set. The inshore fauna (St. Margaret's Bay) was strongly clumped with patchiness at several scales: <10cm in diameter, equal to 10 to 50cm (37% of the species), and>50cm. Polychaetes in samples from off-shore stations were much less aggregated, and discordantly dispersed to varying degrees. The results conform with the present understanding of infaunal spatial patterns and reject the hypothesis that a depth gradient in patchiness exists in addition to the well documented density and biomass gradients.     

广州中心城区公园绿地空间格局及可达性分析

公园绿地是城市中一类典型的开敞空间,对维护城市生态与人居环境健康具有重要意义,其空间布局的合理性与可达性直接影响其对城市居民的服务水平。以广州中心城区为例,借助GIS技术和景观格局指数,分析城市公园绿地景观格局、可达性和服务状况,并探讨城市公园绿地空间格局对其可达性影响。结果表明：①市级公园其面积占公园绿地总面积的84.71%,城市公园绿地聚集度为92.44,广州中心城区公园绿地景观类型和空间格局不尽合理;②网络分析表明研究区仅有22.35%的面积和44.67%的人口能够较便捷地到达邻近公园绿地,广州中心城区公园绿地的可达性和服务效果不理想;③城市公园绿地数量与空间格局是影响其可达性与服务水平的重要因子。     

Community structure of the rocky shore macrobenthos in southern Hokkaido,Japan

Relationships between community structure and environmental factors were sought through multivariate analysis (quantification analysis and correspondence analysis) of data obtained in a benthic macrofauna survey of a rocky low-tide platform located at Usujiri, southern Hokkaido, Japan. A total of 21 species were found. However, their annual mean abundance was dominated by only a few species. Three dominant species of the platform (Chthamalus challengeri, Littorina brevicula andSeptifer virgatus) accounted for an average of 92% of total abundance. Three environmental factors with associated species groups were examined. Among them, micro-topographic characteristics and wave action defined the main correspondence variables.L. brevicula was a characteristic member of the boulder and sheltered field.S. virgatus was the dominant species of sloped surfaces.C. challengeri, S. virgatus, andMytilus edulis were characteristic of ledge or bench environments. Finally,C. challengeri was characteristic of nip and high wave-exposure environments, given its exclusive appearences in these locations. However, as the degree of exposure depends on the scale of wash through the platform, it is directly limited by the microtopographic properties of low-tide platforms. Specific environmental influences such as exposure and height above the datum-plane were rather disapparent. Any overall effects on the community structure were synthesized by those of microtopography. After complete consideration, it was concluded that the community structure of the macrobenthos in this low-tide platform was found to be primarily under the influence of microtopographic characteristics.     

Spatial pattern and persistence of historical fire boundaries in southern interior British Columbia

Recent ecosystem and fire management research aims to quantify, model and understand historical fire disturbances focusing on their frequency, size and distribution. Less attention, however, has been paid to fire boundaries and their location on the landscape. Our study presents a spatial method to quantify the location, pattern and persistence of historical fire boundaries using tree ring fire scar data in the lower Stein watershed (British Columbia). Data from Pinus ponderosa and Pseudotsuga menziesii collected in 35 one-hectare plots over a 412-hectare study area were analyzed for the period between 1879 and 1947 using local spatial statistics and boundary detection techniques. Results of the analysis using local spatial statistic Moran’s I showed significant clustering of boundaries near topographic breaks. To determine and test whether fire boundaries between plots were persistent, we used boundary detection methods and developed a spatially restricted randomization test. The results revealed that out of 86 possible boundary links, 8 were significantly persistent (P < 0.025) while another 8 were significantly rare (P < 0.025). These spatial methods can help determine the historical spatial configuration of persistent boundaries and can be used to maintain natural forest dynamics.

Spatial and temporal pattern in seagrass community composition and productivity in south Florida

We document the distribution and abundance of seagrasses, as well as the intra-annual temporal patterns in the abundance of seagrasses and the productivity of the nearshore dominant seagrass (Thalassia testudinum) in the south Florida region. At least one species of seagrass was present at 80.8% of 874 randomly chosen mapping sites, delimiting 12,800 km² of seagrass beds in the 17,000-km² survey area. Halophila decipiens had the greatest range in the study area; it was found to occur over 7,500 km². The range of T. testudinum was almost as extensive (6,400 km²), followed by Syringodium filiforme (4,400 km²), Halodule wrightii (3,000 km²) and Halophila engelmanni (50 km²). The seasonal maxima of standing crop was about 32% higher than the yearly mean. The productivity of T. testudinum was both temporally and spatially variable. Yearly mean areal productivity averaged 0.70 g m⁻²day⁻¹, with a range of 0.05–3.29 g m⁻² day⁻¹. Specific productivity ranged between 3.2 and 34.2 mg g⁻¹ day⁻¹, with a mean of 18.3 mg g⁻¹ day⁻¹. Annual peaks in specific productivity occurred in August, and minima in February. Integrating the standing crop for the study area gives an estimate of 1.4 × 1011 g T. testudinum and 3.6 × 10¹⁰ g S. filiforme, which translate to a yearly production of 9.4 × 10¹¹ g T. testudinum leaves and 2.4 × 10¹¹ g S. filiforme leaves. We assessed the efficacy of rapid visual surveys for estimating abundance of seagrasses in south Florida by comparing these results to measures of leaf biomass for T. testudinum and S. filiforme. Our rapid visual surveys proved useful for quantifying seagrass abundance, and the data presented in this paper serve as a benchmark against which future change in the system can be quantified. Received: 30 January 2000 / Accepted: 24 July 2000     

梅江流域鸟类群落结构及其多样性

采用固定样带法和样点法对梅江流域的鸟类群落进行了研究,共记录到201种,隶属16目49科127属,其中留鸟81种、冬候鸟67种、夏候鸟40种、旅鸟13种,分别占40．1％、33．3％、19．9％、6．7％;古北界种类95种（占47．3％）,东洋界种类64种（占31．8％）,广布型种类42种（占20．9％）;国家I级保护种类1种,国家II级保护种类21种（占10％）;《国际湿地公约》指定种类24种（占12％）,《中澳候鸟保护协议》指定种类22种（占11％）,《中日候鸟保护协议》指定种类76种（占38％）,《濒危野生动植物种国际贸易公约》（CITES）指定种类19种（占9％）,有益的、有重要经济价值的、有重要科学研究价值的物种155种（占77％）。该流域的鸟类群落多样性指数3．7617,均匀度指数0．7093。     

Community responses to UV radiation. II. Effects of solar UVB on field-grown diatom assemblages of the Carribean

The effects of ambient solar UV on community productivity and structure were assessed during primary succession of benthic diatoms on artificial substrate in a coral reef of the Caribbean. Artificial substrates, partially enclosed by UV cutoff filters, were placed at a depth of 60 cm below surface. During the initial colonization stages, the assemblages exposed to the full solar spectrum had a mean productivity 43.4% lower than the assemblages exposed to PAR+UVA only. Some differences in species diversity of assemblages under the different UV treatments were also observed. Sensitive species to UVB exposure were Mastogloia angulata, M. ovata, M. paradoxa, Nitzschia longissima, Plagiogramma staurophorum, Rhopalodia musculus, and Surirella ovata. These UVB effects gradually diminished as succession proceeded; 5 to 6 weeks after the placement of the substrates in the water, no significant differences in productivity were observed between the different treatments, while after 6 weeks of growth, species diversity and evenness were higher, although not statistically significant, in the UVB-exposed assemblages. During the first 2 weeks of growth, the productivity under PAR+UVA was significantly lower than that under PAR only. Received: 12 July 1996 / Accepted: 20 November 1997     

Community structure and the effects of pollution in sea-grass meadows and adjacent habitats

Differences in the structure of epibenthic invertebrate species assemblages were investigated in two estuarine areas in Apalachee Bay, Florida (USA), and related to the presence or absence of pulp-mill effluents. Invertebrate species associated with sea-grass beds, mud flats, and oyster reefs were included in the analyses. Surprisingly, several commonly used indicators of pollution stress were ineffective in differentiating the study areas, even though there were large differences in abundance and dominance relationships between them, and these differences were clearly related to the presence of the pulp-mill effluents. Recommendations for data analyses in similar types of studies are made, based on the results of this investigation and others in the same study areas.