Staging of Pacific flyway brant in relation to eelgrass abundance and site isolation, with special consideration of Humboldt Bay, California     

Jeffrey E. Moore  Mark A. Colwell  Ryan L. Mathis  Jeffrey M. Black 《Biological conservation》2004,115(3):475-486

Spring distributions of black brant (Branta bernicla nigricans) are closely related to that of their primary food plant, eelgrass (Zostera marina). Using historical (1931-2001) brant data from Humboldt Bay, California, we show that proportional use of two main feeding areas in the bay strongly reflects food abundance. We used multiple regression to investigate whether the spatial relationship between brant and eelgrass holds at the flyway level. We related peak brant numbers at 11 staging areas in the Pacific flyway to the sites' Z. marina abundance and isolation from other important staging areas. We explained 90% of the variation in peak brant numbers across sites with these variables; isolated bays with high eelgrass abundance supported the most brant. Our results emphasize the importance of protecting large eelgrass habitats along the Pacific Coast, particularly in bays that are geographically isolated from other large staging areas.  相似文献   

Estimates of the Enchytraeidae (Oligochaeta,Annelida) contribution to energy flow in the soil system of an acid beech wood forest     

J. Römbke 《Biology and Fertility of Soils》1991,11(4):255-260

Summary The data introduced here are part of a project lasting from 1976 to 1985 in an acid beech wood forest in the northern part of the Black Forst in Southern Germany. With Enchytraeidae (Oligochaeta) as an example, attempts were made to determine the part played by the mesofauna in the soil system. Parameters such as respiration, production, and consumption were estimated using abundance and biomass data as a basis. The results show that not only the Enchytraeidae but even single species like Cognettia sphagnetorum or Mesenchytraeus glandulosus contribute a measurable amount to the energy flow of the soil ecosystem. The respiration of the whole population, for example, corresponds to 3.4% of the total energy input via leaf litter, and consumption amounts to 8.1% of the total litter including twigs. It seems that the Enchytraeidae contribute around 60% of the total soil animal respiration in this acid beech wood, and thus play an important role in soil renewal.  相似文献   

白令海阿留申海盆区狭鳕当年生幼鱼数量分布的调查研究   总被引：1，自引：0，他引：1  

唐启升  金显仕  李富国  陈聚法  王为祥  陈毓桢  赵宪勇  代芳群 《中国水产科学》1994,1(1):37-47

１９９３年夏季白令海狭鳕资源调查期间，作者等应用声学／拖网评估调查方法，首次发现阿留申海盆区有大量当年生狭鳕幼鱼分布。研究结果表明：（１）当年生幼鱼主要分布在海盆区东北部，密集区位于东白令海陆架斜坡与公海区之间，呈西北东南走向；（２）鱼群主要栖息于中上层８０—１２０米处，有明显的昼夜垂直移动现象；（３）７月份海盆区东北部幼鱼鱼体长度为２９—４７毫米，而南部波哥斯洛夫岛附近的鱼体长度仅为１１—１７毫米，系两个不同产卵期鱼群的子代；（４）幼鱼主要栖息层的水温为３—５℃，盐度为３２．９—３３．１，其分布与陆架斜坡地理环境和饵料生物关系较密切。  相似文献   

Energetic equivalence in a soil arthropod community from an aspen-conifer forest     

Timothy D. Meehan  Perrin K. Drumm  R. Schottland Farrar  Kaan Oral  Karen E. Lanier  Elden A. Pennington  Lindsey A. Pennington  Isabel T. Stafurik  Dante V. Valore  Amanda D. Wylie 《Pedobiologia》2006,50(4):307-312

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Near infrared reflectance spectroscopy (NIRS) could be used for characterization of soil nematode community     

Bernard G. Barthès  Didier Brunet  Oumar Ba 《Soil biology & biochemistry》2011,43(8):1649-1659

Studying soil nematofauna provides useful information on soil status and functioning but requires high taxonomic expertise. Near infrared reflectance (NIR) spectroscopy (NIRS) has been reported to allow fast and inexpensive determination of numerous soil attributes. Thus the present study aimed at assessing the potential of NIRS for determining the abundance and diversity of soil nematodes in a set of 103 clayey topsoil samples collected in 2005 and 2006 from agricultural soils in the highlands of Madagascar.The morphological characterization of soil nematofauna involved extraction through elutriation then counting under binoculars and identification at family or genus level using microscopy, on ca. 150-g fresh soil samples. Taxa were assigned to five trophic groups, namely bacterial feeders, fungal feeders, obligate plant feeders, facultative plant feeders, and omnivores and predators (together). In addition, four ecological indexes were calculated: the Enrichment index, Structure index, Maturity index, and Plant parasitic index.Oven-dried (40 °C) < 2-mm sieved 5-g soil subsamples were scanned in the NIR range (1100-2500 nm), then spectra were fitted to nematofauna data using partial least square regression. Depending on the sample set considered (year 2005, year 2006, or both years), NIRS prediction of total nematode abundance was accurate (ratio of standard deviation to standard error of cross validation, i.e. RPD ≥ 2) or acceptable (RPD ≥ 1.6). Predictions were accurate, acceptable, or quasi-acceptable (RPD ≥ 1.4) for several of the six most abundant taxa, and to a larger extent, for most trophic groups (except facultative plant feeders); but they could not be made for taxa present in a small number of samples or at low abundance. By contrast, NIRS prediction of relative abundances (in proportion of total abundance) was poor in general, as was also the prediction of ecological indexes (except for the 2006 set). On the whole, these results were less accurate than NIRS predictions of soil attributes often reported in the literature. However, though not very accurate, NIRS predictions were worthwhile considering the labor-intensity of the morphological characterization. Most of all, NIRS analyses were carried out on subsamples that were probably too small (5 g) to allow representative sampling of nematofauna. Using larger samples for NIRS (e.g. 100 g) would likely result in more accurate predictions, and is therefore recommended. Scanning un-dried samples could also help improve prediction accuracy, as morphological characterization was carried out on samples not dried after sampling.Examining wavelengths that contributed most to NIRS predictions, and chemical groups they have been assigned to, suggested that NIRS predictions regarding nematofauna depended on constituents of both nematodes and preys’ food. Predictions were thus based on both nematofauna and soil organic properties reflected by nematofauna.  相似文献   

山西特早熟棉区棉铃虫发生特点及防治对策研究初报     

马利平  周运宁 《山西农业科学》1996,24(2):62-64

１９９３～１９９５年，在晋中祁县从５月上旬到８月底利用棉铃虫性诱剂对棉铃虫的发生代数、发生时期等进行了观察。晋中特早熟棉区棉铃虫一年发生４代。越冬代成虫发生期为５月中旬至６月上旬，以后各代约间隔一个月发生。造成为害的主要为２代，３代次之。据此，提出了以化学防治为主、生物防治为辅的重点防治２代、３代棉铃虫的防治对策。  相似文献   

绵阳雏鳳山及周边冬·春季白颊噪鹛数量及分布     

潘红星  刘杰  涂朝勇  李容  朱东阳  刘宁 《安徽农业科学》2013,41(8):3386-3387,3402

2009年11月～2010年4月,采用样线调查法对雏鳳山及周边环境冬春两季白颊噪鹛(Garrulax sannio)数量及分布进行了调查。共记录实体4 073只次,其中冬季2 003只次,春季2 070只次。结果表明,白颊在调查区均有分布,乔灌林的种群数量明显高于河道,其遇见率为37.167只次/(h.km),河道遇见率为12.615只次/(h.km),其他区域遇见率约为12.667～17.308只次/(h.km);春季数量略高于冬季,与生存和繁殖相关资源条件(食物、水分、隐蔽条件)较优越的生境其分布数量明显较多,干扰较大的公路沿线绿化林地有相当大的数量。最后,对此次调查研究方法的可靠性及其数量分布的差异进行了分析,同时对城市及近郊开展鸟类保护工作提出了建议。  相似文献   

Effects of landscape patterns on species density and abundance of trees in a tropical subdeciduous forest of the Yucatan Peninsula     

J. Luis Hernndez-Stefanoni  Juan Manuel Dupuy 《Forest Ecology and Management》2008,255(11):3797-3805

Most studies of the effects of fragmentation and landscape patterns on plant communities focus on particular patches and on local species richness (α-diversity), while few studies examine different patch-types at the whole landscape level and address effects on abundance and composition of species or functional groups. The present study aims to identify and characterize relationships between patch-type metrics and species density and abundance of trees using four tropical subdeciduous forest landscapes in the Yucatan Peninsula considering the entire landscape as the unit of study. Species density and abundance of different groups of tree species resulting from hierarchical clustering were related to landscape patterns of patch-types (area, edge, shape, similarity and contrast) using regression analysis and Akaike Information Criterion (AIC). The abundance of tree species in the oldest stages of succession was associated with percentage of land of a patch-type. Total area may favor the establishment of shade-tolerant tree species in the study area because as the area of forest patches increases, the area of forest interior conditions also increases. Conversely, the abundance of species at early and intermediate stages was related to total edge contrast and edge density, respectively. Fragmentation increases the proportion of edge zones of a patch-type, creating contrasting microclimate conditions that could promote the establishment of pioneer and light-demanding species. Thus, the combined effect of total area and edge length of a patch-type may enhance total tree species richness in the study area by favoring species with different life-history strategies. The appearance of area, shape, edge and contrast in most of the regression models suggests that some generalization can be made about the effects of spatial geometry of patch-types on species composition and abundance of tropical trees. Understanding associations between landscape metrics and species density and abundance of objectively derived groups or guilds of species can provide important insights on the effects of fragmentation and landscape pattern on these guilds and on overall α-diversity, as well as guidelines for their conservation and management.  相似文献   

晋东南地区城市公园景观中地域文化的多样性及其表达          下载免费PDF全文

申小雪  武小钢  杜景新  郭春瑞 《农学学报》2017,7(7):47-53

为解决城市建设中地域文化景观特色衰退的问题,以城市公园景观为研究对象,根据地域文化设计表达上的常用手法对地域文化进行分类,参照植物多样性研究方法对山西省晋东南地区长治、晋城市的城市公园中地域文化景观进行了研究。调查结果表明,整体上地域文化的丰富度不高,地域文化中缺少地域历史遗迹的保留。在5类地域文化中,艺术再创造类景观占有绝对优势,生活场景再现类景观的数量、多样性及文化表达等各项指标值都最小。地域文化艺术再创造和历史题材的借鉴类景观在设计与表达方面效果很好,表现形式主要为雕塑及景墙,文化题材丰富,但地域文化的表达在景观要素上种类单一,缺乏对地域文化表现形式的创新,地域文化内在含义挖掘不够深刻,多为表面形式展示,而缺少对文化的深层挖掘与传达。  相似文献   

Forecasting vole population outbreaks in forest plantations: The rise and fall of a major mammalian pest     

Thomas P. Sullivan  Druscilla S. Sullivan 《Forest Ecology and Management》2010

Voles of the genera Microtus and Myodes feed on tree seedlings planted on cutover forest land in temperate and boreal forests of North America and Eurasia. This damage may have serious economic implications as well as limit regeneration of appropriate tree species in certain forest ecosystems. Prediction of vole population outbreaks and feeding damage to forest plantations, across even a limited geographic range, has yet to be achieved in North America. Thus, a major objective was a detailed analysis of changes in population dynamics of long-tailed voles (Microtus longicaudus), and to test three hypotheses (H) that vole populations would: (H₁) rise and fall in accordance with the abundance of herbaceous plants (grasses and forbs) during early vegetative succession after forest harvesting, (H₂) be positively associated with grass-seeded sites; and (H₃) incidence of feeding damage to seedlings would be positively associated with vole abundance. Voles were live-trapped for 6 years (2004–2009) from the time of harvesting on intensive sites, as well as surveyed over a range of extensive sites. Population numbers were related to habitat characteristics and tree damage in young forest plantations near Golden, British Columbia, Canada.  相似文献