New Zealand machair vegetation

Abstract. Machair vegetation is reported for the first time from New Zealand. The habitat is similar to that of British machairs in climate, topography and generally in soil. pH and CaCO₃ content are much lower through most of the sequence, though this difference may partly reflect the greater disturbance of British machair. Sea machair is present, predominantly comprising native species. This grades into machair proper, which contains many species found also in British machair. The machair includes Ammophila-occupied hillocks, a feature typical of British machair. Machair marsh is also present.     

Habitat use by fishes after tidal reconnection of an impounded estuarine wetland in the Indian River Lagoon,Florida (USA)

Most of the wetlands located along the Indian River Lagoon (IRL) ineast-central Florida (USA) have been impounded since the 1950's and1960's to reduce mosquito reproduction. Impounded marsh (i.e.,impoundment) dikes physically separate the wetlands from the estuary toallow artificial flooding of the impoundments during the mosquito breedingperiod (May to October). Presently, Rotational ImpoundmentManagement (RIM) is the preferred impoundment management techniquein the IRL. Impoundments maintained under RIM have culverts installedthrough the dikes which are kept closed during the mosquito breedingseason (to control mosquitos) and are allowed to remain open for theremainder of the year (to allow tidal flow). A 24.3 ha impoundment8 km north of Sebastian Inlet that had been isolated from the IRL for over39 years was studied for 12 months to determine habitat use by fishes aftertidal reconnection and the implementation of RIM. Fish sampling wasconducted with a seine in the perimeter ditch and with clover and minnowtraps in the upper marsh and tidal creek areas of the impoundment. Waterlevel, impoundment bottom topography, and the seasonal nursery functionof the impoundment were factors that contributed to observed patterns offish habitat use during the study. Within the first 15 weeks of perimeterditch sampling, an increase from 9 to 40 species was observed. Transientspecies used the perimeter ditch almost exclusively and entered theimpoundment primarily during the spring open period. Juvenile Pogonias cromis (Linnaeus), Elops saurus Linnaeus, Centropomusundecimalis (Bloch), and Megalops atlanticus Valenciennes were themost abundant recreationally important species, respectively. Habitat useby the most abundant resident species (Gambusia holbrooki Girard,Poecilia latipinna (Lesueur), Cyprinodon variegatus Lacepède, andFundulus confluentus Goode & Bean) was influenced primarily bywater level fluctuations. Resident species used the upper marsh and tidalcreek habitats during summer flooded periods and the cyprinodontids leftthe interior surface of the impoundment last as water levels decreased. Thisstudy is the first to document the recovery of fish populations in areconnected impoundment north of Sebastian Inlet using both active andpassive sampling techniques.     

长江口芦苇和互花米草盐沼湿地蟹类洞穴分布特征及主要影响因子

蟹类洞穴是蟹类在潮间带盐沼生存、繁衍的特征性结构,具有重要的生态功能。洞穴分布特征及其影响因子的分析,是深入探讨蟹类及其洞穴的生态系统功能的重要基础。2015年10月,在崇明北滩单一芦苇(Phragmites australis)群落,单一互花米草(Spartina alterniflora)群落和芦苇-互花米草混合群落3种典型生境中,对蟹类洞穴的分布特征及其相关的大型底栖动物、植被、沉积物等的特征参数进行了调研与分析。结果表明,生境类型差异对蟹类洞穴分布特征及相关生境因子具有重要影响。蟹类洞穴的分布密度和开口直径在不同生境间存在显著差异(P0.05),且单一芦苇群落生境内洞穴密度要显著高于单一互花米草群落生境(P0.05),洞穴开口直径在单一互花米草生境要显著高于单一芦苇生境(P0.05);大型底栖动物生物量、密度、植物地下部分生物量在不同生境间差异不显著(P0.05),而植株密度、活植株高度、植物地上部分生物量以及沉积物含水率、p H、氧化还原电位在不同生境间存在显著差异(P0.05)。沉积物中值粒径,总氮含量和总碳含量在不同生境间的差异随深度不同会发生变化。不同生境主要生境因子的差异是导致蟹类洞穴分布特征不同的根本原因;蟹类洞穴分布特征受多个生境因子的综合作用。筛选的生境因子的组合虽然与洞穴分布特征具有显著相关性,但相关系数较小。未来研究中需要拓展生境因子涵盖范围,加强多因子综合作用分析。     

降雨和汇流对黑土区坡面土壤侵蚀的影响试验研究

东北黑土区上坡汇流对坡面土壤侵蚀有重要影响,因此辨析降雨和汇流对黑土区坡面土壤侵蚀的影响对农田土壤侵蚀防治有重要意义。通过设计不同降雨强度和汇流速率以及二者组合的模拟降雨及上方汇流试验,分析了降雨和汇流对黑土坡面侵蚀的影响及其贡献。试验处理包括两个降雨强度(50 mm/h和100 mm/h)、两个汇流速率(50 mm/h和100 mm/h,即:10 L/min和20 L/min)、以及4种不同降雨强度和汇流速率的组合((50+50)mm/h、(50+100)mm/h、(100+50)mm/h和(100+100)mm/h)。结果表明,在50 mm/h和100 mm/h上方汇流引起的坡面侵蚀量仅分别是50 mm/h和100 mm/h降雨引起坡面侵蚀量的1.9%和0.6%;当降雨强度和坡上方汇流速率分别由50 mm/h增加至100 mm/h时,降雨试验处理下的坡面侵蚀量增加6.1倍,汇流试验处理下的坡面侵蚀量增加3.2倍,说明降雨对坡面土壤侵蚀的影响显著大于汇流的作用。在降雨和汇流组合试验中,总供水强度(降雨强度+汇流速率)为150 mm/h时,降雨强度为100 mm/h和汇流速率为50 mm/h组合试验的坡面侵蚀量是降雨强度为50 mm/h和汇流速率为100 mm/h组合试验坡面侵蚀量的7.9倍。在相同汇流条件下,降雨强度由50 mm/h增加到100 mm/h时,降雨强度的增加对坡面侵蚀量的贡献率为89.6%-99.5%;而在相同降雨条件下,坡面汇流速率由50 mm/h增加100 mm/h时,汇流速率的增加对坡面侵蚀量的贡献率为17.2%-78.7%,说明在东北黑土区防治坡面汇流对坡面土壤侵蚀影响也尤为重要。     

Factors influencing occupancy and density of salt marsh songbirds in northeast Florida

Salt marshes and the organisms that depend on them are subject to a variety of anthropogenic threats. In Florida, Worthington’s Marsh Wrens (Cistothorus palustris griseus) and MacGillivray’s Seaside Sparrows (Ammospiza maritima macgillivraii) are species of concern that inhabit a small, narrow range of salt marsh in the northeastern corner of the state, an area of increasing human development. The historic ranges of these subspecies encompassed salt marshes in five counties, but their ranges had contracted to just two counties by the early 2000s and their populations declined. We surveyed the historic ranges of the two subspecies during the breeding seasons of 2014 and 2015 to document their distributions, identify habitat features that influenced occupancy and density, and assess whether any recolonization had occurred in areas previously abandoned. We found that the ranges of both subspecies remained relatively stable compared to the early 2000s, with no signs of either further contraction or recolonization. Both Marsh Wrens and Seaside Sparrows were more likely to occupy areas farther from uplands. Marsh Wren occupancy was positively associated with marshes dominated by smooth cordgrass (Spartina alterniflora) and negatively associated with marshes dominated by black needlerush (Juncus roemerianus). Seaside Sparrows were more likely to occur at sites of moderate elevation. We found greater densities of both subspecies in areas farther from uplands, with moderate elevations, and dense vegetation. Marsh Wren density also increased in smooth cordgrass marshes, whereas sparrow numbers increased in areas of moderate vegetation height. Despite these differences between subspecies, the need for dense vegetation away from uplands highlights the importance of smooth cordgrass marshes in the region.     

Microhabitat use by marsh-edge fishes in a Louisiana estuary

Synopsis We used a drop sampler to characterize use of the marsh-edge ecotone by small fishes along two transects running inland from the Gulf of Mexico for ca. 25 km in Louisiana's Barataria-Caminada Bay System. Monthly sampling was stratified among upper, middle, and lower reaches and within reaches to characterize fish responses to salinity, depth, distance from shore, substrate, dissolved oxygen concentration, temperature, turbidity, velocity, and emergent stem density. In 681 quantitative samples, covering 658 m², collected between October 1987 and October 1989, we collected 57 fish species and 16 864 individuals, primarily larvae and juveniles. The 15 most abundant fishes, comprising 97.7% of all individuals, were concentrated near the marsh edge (i.e., 0 to 1.25 m distance). Some significant differences within species for seasonal variables (e.g., temperature and dissolved oxygen concentration) reflected the ephemeral duration of early life history stages. Other differences reflected ontogenetic microhabitat shifts (e.g., depth and distance from shore). Within ecological groups, characterized as demersal residents, nektonic transients, and demersal transients, spatial and temporal segregation reflected the particular habitat requirements of each species. In a principal component analysis of microhabitat use, the first three components were interpreted as seasonal, depth-and-distance, and salinity axes, respectively. The array of species and size classes in principal component space reflected the complex dimensionality of microhabitat use. The high density of fish larvae and juveniles near the marsh edge confirmed the importance of the marsh-edge ecotone as a nursery for many estuarine-dependent fishes.     

子宫颈糜烂病毒病因的探讨

491份宫颈拭子病毒分离结果表明:糜烂宫颈单纯疱疹病毒(HSV)分离阳性率(30.8％)是正常宫颈(2.6％)的11.8倍,用人干扰素治疗一个疗程后,病毒分离率下降至疗前的1/4.36例糜烂宫颈活体组织DNA分子杂交表明,乳头瘤病毒16型(HPV-16)阳性者占52.8和,HPV-18占17.9％,HPV-6B占28.1％,HPV-11占7.7％,251例宫颈糜烂患者经人(?)D型基因工程干扰素双盲对比治疗后,总有效率达93.8％,显效率达60％,分析临床疗效与HSV分离率的变化表明,临床有效病例中有35％(49/140)在治疗后病毒阴转,有57％在疗前疗后均未分离出HSV,有5％在疗前疗后保持阳性不变,有2.9％疗前阴性,疗后阳性,上述结果表明,HSV和HPV与慢性宫颈炎有一定关系。     

Screening for bacterial-fungal associations in a south-eastern US salt marsh using pre-established fungal monocultures

Both bacteria and fungi play critical roles in decomposition processes in many natural environments, yet only rarely have they been studied as an integrated community. We examined whether physical associations exist between individual bacterial and fungal species that co-occur on decaying smooth cordgrass, Spartina alterniflora, in a south-eastern US salt marsh. Fungal-pervaded decaying Spartina was used as "bait" for potential bacterial associates. The bundles (infiltrated with one of three dominant fungal members of the decomposer assemblage, or an autoclaved control) were placed in a salt marsh and collected biweekly for 6 weeks during the first experiment (late summer 2002), and weekly for 3 weeks during the second experiment (early summer 2003). Terminal-restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes was used to track colonization by bacterial taxa in association with the established fungal species. T-RFLP analysis of 18S-to-28S internal transcribed spacer (ITS) regions was used to monitor changes in fungal communities once bundles had been placed in the field. Results from both years were nearly identical, and showed that invasion by fungi other than the bait species was slow, resulting in a virtual fungal monoculture for several weeks into the experiments. Surprisingly, bacterial communities were unaffected by the identity of the fungal bait. Regardless of the fungal species, and even in the absence of prior fungal colonization, bacterial 16S rRNA profiles were remarkably similar. These results suggest that few species-specific associations, either positive or negative, exist between bacterial and fungal members of the Spartina decomposer community during initial colonization.     

Implications of land-cover types for soil erosion on semiarid mountain slopes: Towards sustainable land use in problematic landscapes

The impact of land-cover types on soil erosion and runoff, as well as on physico-chemical soil properties, was monitored. The study area, an agroforestry landscape was located in Sierra Nevada Mountains in south-eastern Spain. Eight land-cover types were investigated: farmland planted with olive, almond, and cereals; forest with P. halepensis and P. sylvestris; shrubland; grassland; and abandoned farmland. The erosion plots replicated twice were located on hillslopes, where erosion and runoff were measured after 22 storm events. Forest dominated by Pinus stands exhibited significantly the lowest amounts of erosion and runoff, contrasting with abandoned farmland. Olive had higher erosion than did almond, cereals, or grasslands, but with the highest runoff rate under almond groves. The erosion and runoff response to shrubland showed an intermediate situation between forest and farmland–grassland uses. Under forest and shrubland, better soil properties were determined, especially higher organic C and total N, and lower soil-bulk density. Erosion was highly dependent on runoff, bulk density, soil organic C, and the degree of soil surface covered. Thus, the alteration in land cover is essential to an understanding of productivity of soil undergoing erosion, as sustainable planning can mitigate soil-degradation processes in the overall agroforestry landscape.