Geographical patterns in openland cover and hayfield mowing in the Upper Great Lakes region: implications for grassland bird conservation

Populations of many grassland bird species such as Grasshopper Sparrow (Ammodramus savannarum), Henslow’s Sparrow (A. henslowii), and Bobolink (Dolichonyx oryzivorus) have experienced considerable declines over the last century. To foster multi-species grassland bird conservation in the Upper Great Lakes (UGL) states of Michigan, Minnesota, and Wisconsin, we quantified geographic patterns within three sub-regional zones (e.g., North, Central, and South) of the UGL. Patterns of interest included the distribution and abundance of openland cover type (including managed pasture-hayland), the distribution, phenology, habitat affinity, and long-term population trends of ten grassland bird species, and (in particular) the geographic patterns in hayfield mowing and the temporal changes in hayfield cover. Approximately 10, 38, and 53% of the UGL openland was proportioned in the North, Central, and South zones, respectively. The distribution of hayland also varied by zone: North, 17%; Central, 46%; and South, 37%. In the central portion of the UGL where the greatest area is devoted to hay production, alfalfa—more intensively managed than mixed-grass hay—predominates. Although we found significance differences (P < 0.05) in hayfield mowing intensity between zones (with the majority of land under relatively low-intensity mowing found in the North Zone, particularly the Upper Peninsula of Michigan) no strong relationships were found between hayfield mowing patterns, other land cover-land use variables, and bird population trends at finer scales of study. Nonetheless, we suggest that the geographic patterns illustrated here provide useful information for grassland bird conservation planning across the UGL.     

The future demographic niche of a declining grassland bird fails to shift poleward in response to climate change

Context

Temperate grasslands and their dependent species are exposed to high variability in weather and climate due to the lack of natural buffers such as forests. Grassland birds are particularly vulnerable to this variability, yet have failed to shift poleward in response to recent climate change like other bird species in North America. However, there have been few studies examining the effect of weather on grassland bird demography and consequent influence of climate change on population persistence and distributional shifts.

Objectives

The goal of this study was to estimate the vulnerability of Henslow’s Sparrow (Ammodramus henslowii), an obligate grassland bird that has been declining throughout much of its range, to past and future climatic variability.

Methods

We conducted a demographic meta-analysis from published studies and quantified the relationship between nest success rates and variability in breeding season climate. We projected the climate-demography relationships spatially, throughout the breeding range, and temporally, from 1981 to 2050. These projections were used to evaluate population dynamics by implementing a spatially explicit population model.

Results

We uncovered a climate-demography linkage for Henslow’s Sparrow with summer precipitation, and to a lesser degree, temperature positively affecting nest success. We found that future climatic conditions—primarily changes in precipitation—will likely contribute to reduced population persistence and a southwestward range contraction.

Conclusions

Future distributional shifts in response to climate change may not always be poleward and assessing projected changes in precipitation is critical for grassland bird conservation and climate change adaptation.

     

Effects of patch size,isolation and regional abundance on forest bird communities

The aim of this study was to assess the impact of isolation on forest bird communities in agricultural landscapes in The Netherlands. We studied the avifauna of 235 small (0.1–39 ha) woodlots composed of mature deciduous trees in 1984–1985. These woodlots were selected in the eastern and central/southern part of the country within 22 regions showing great differences in landscape structure,i.e., degree of isolation. Multiple regression analysis indicated that woodlot size was the best single predictor of species number and probability of occurrence of most species. It turned out that the isolation variables, area of wood, number of woods, interpatch distance, and proximity and density of connecting elements, explained small but significant parts of the residual variances in species number. No single species was significantly affected by the density of connecting elements. Biogeographical differences between two groups of regions were emphasized. Evidence of four woodland species suggested that regional abundance affected the probability of occurrence in small isolates.     

Declines in biodiversity and the abundance of pest species across land use gradients in Southeast Asia

Context

Changes in land use have disruptive effects on community structure, causing many species to disappear, though a few thrive and become pests.

Objectives

To gain understanding on how anthropogenic activity changes spatial patterns of native species diversity while favoring pests, we conducted rapid biodiversity assessments of dacine fruit flies across eight regions in Southeast Asia.

Methods

Male lure traps were maintained for 2 days along transects at 233 sites, in forest, agricultural and urban environments.

Results

A total of 8393 individuals were collected, belonging to 57 described and 4 new or unidentified species. The majority (78 %) of individuals belonged to 14 pest species, dominated by Bactrocera dorsalis (Hendel). The 57 species represent 38 % of those recorded from the region, indicating effective sampling. Individual flies were collected in highest numbers in urban and agricultural sites, but species diversity was low. Forest samples yielded fewer specimens but highest species diversity, suggesting a shift in community structure after disturbance, benefiting a few pest species at the expense of the broader community, even in the same genus and ecological guild.

Conclusions

Dacine fruit flies may be useful in assessing habitat quality and bait systems permit the execution of rapid biodiversity and multi-species conservation assessments. Our results apply to broader patterns concerning biodiversity loss and the emergence of pest species under increasingly intensive land use gradients, and demonstrate the remarkable loss of biodiversity over very narrow distances as forest is converted into agricultural use, hence the importance in maintaining a mosaic of native habitats.

     

The effects of a vegetational corridor on the abundance and dispersal of insect biodiversity within a northern California organic vineyard

During 1996 and 1997, two adjacent 2.5 has organic vineyard blocks (A and B) were monitored to assess the distributional and abundance patterns of the Western grape leafhopper Erythroneura elegantula Osborn (Homoptera: Cicadellidae) and its parasitoid Anagrus epos Girault (Hymenoptera: Mymaridae), Western flower thrips Frankliniella occidentalis (Pergande) and generalist predators. The main difference between blocks was that block A was cut across by a corridor composed of 65 flowering plant species which was connected to the surrounding riparian habitat, whereas block B had no plant corridor. In both years, leafhopper adults and nymphs and thrips tended to be more numerous in the middle rows of block A and less abundant in border rows close to the forest and corridor where predators were more abundant. The complex of predators circulating through the corridor moved to the adjacent vine rows and exerted a regulatory impact on herbivores present in such rows. In block B all insects were evenly distributed over the field, no obvious density gradient was detected from the edges into the center of the field. Although it is suspected that A. epos depended on food resources of the corridor, it did not display a gradient from this rich flowering area into the middle of the field. Likewise no differences in rates of egg parasitism of leafhoppers could be detected in vines near the corridor or in the vineyard center. The presence of riparian habitats enhanced predator colonization and abundance on adjacent vineyards, although this influence was limited by the distance to which natural enemies dispersed into the vineyard. However, the corridor amplified this influence by enhancing timely circulation and dispersal movement of predators into the center of the field.     

Contrasting impacts of invasive plants and human-altered landscape context on nest survival and brood parasitism of a grassland bird

Context

Humans have altered grasslands in recent decades through crop conversion, woody encroachment, and plant invasions. Concurrently, grassland birds have experienced range-wide declines. Studies have reported effects of plant invasions and land conversion on nest ecology, but few have assessed relative impacts of these changes.

Objectives

We compared impacts of invasive plants and landscape context on nest survival of a grassland songbird, the dickcissel (Spiza americana). We also compared effects on parasitism by brown-headed cowbirds (Molothrus ater) and tested whether parasitism affects survival.

Methods

From 2013–2016, we monitored 477 dickcissel nests. We measured nest-site vegetation (including woody plants, tall fescue Schedonorus arundinaceous, and other invasive grasses) and measured landscape context at broad scales.

Results

Nest survival declined with increasing tall fescue cover at nest sites, and parasitism was more common at nests with greater fescue and woody cover. Some evidence suggested a negative effect of row-crop cover within 1000 m on nest survival, but no landscape patterns unambiguously affected survival. Woodland cover and wooded-edge prevalence were associated with reduced parasitism risk. Parasitized nests had smaller clutches, failed more frequently, and produced fewer fledglings than non-parasitized nests.

Conclusions

Determining the impacts of invasive plants and other anthropogenic changes on grassland birds will aid in prioritizing management to improve habitat quality. Our results indicate that optimizing landscape context around habitats may not affect dickcissel nest survival strongly, except perhaps through effects on parasitism. In contrast, controlling tall fescue and shrubs within grasslands could benefit birds by increasing nest success and reducing parasitism.

     

Potential cheatgrass abundance within lightly invaded areas of the Great Basin

Landscape Ecology - Anticipating where an invasive species could become abundant can help guide prevention and control efforts aimed at reducing invasion impacts. Information on potential abundance...     

Effects of spatial scale and taxonomic group on partitioning of butterfly and bird diversity in the Great Basin,USA

Different taxonomic groups perceive and respond to the environment at different scales. We examined the effects of spatial scale on diversity patterns of butterflies and birds in the central Great Basin of the western USA. We partitioned the landscape into three hierarchical spatial levels: mountain ranges, canyons, and sites within can yons. We evaluated the relative contribution of each level to species richness and quantified changes in species composition at each level. Using additive partitioning, we calculated the contribution of spatial level to overall species diversity. Both canyon and mountain range had significant effects on landscape-level species richness of butterflies and birds. Species composition of butterflies was more similar in space than species composition of birds, but assemblages of both groups that were closer together in space were less similar than assemblages that were further apart. These results likely reflect differences in resource specificity and the distribution of resources for each group. Additive partitioning showed that alpha diversity within canyon segments was the dominant component of overall species richness of butterflies but not of birds. As the size of a sampling unit increased, its contribution to overall species richness of birds increased monotonically, but the relationship between spatial scale and species richness of butterflies was not linear. Our work emphasizes that the most appropriate scales for studying and conserving different taxonomic groups are not the same. The ability of butterflies and birds to serve as surrogate measures of each others diversity appears to be scale-dependent.This revised version was published online in May 2005 with corrections to the Cover Date.     

A riverscape perspective on habitat associations among riverine bird assemblages in the Lake Champlain Basin,USA

The riverscape perspective recognizes the heterogeneous habitat types within the stream corridor as a single, integrated ecological unit operating across spatial scales. Although there is ample evidence that the riverscape notion is appropriate in understanding the physical phenomena of stream corridors, significantly less attention has focused on its ecological ramifications. To this end, we surveyed riverscape habitat variables and bird community characteristics in the Champlain Valley of Vermont, USA. From the data collected, we used information theoretic methodology (AIC_c) to model relationships between bird community attributes and key habitat variables across the riverscape. Our models with the greatest support suggest that riverine bird communities respond to a suite of characteristics; representing a variety of riverscape habitats at the in-stream, floodplain, and riparian levels. Channel slope, drainage area, percent conifers, and in-stream habitat condition were among the most influential variables. We found that piscivores are potentially important indicators of riverscape condition, responding to a host of variables across the riverscape. Our results endorse a holistic approach to assessing and managing the mosaic of patches in the riverscape and suggest that a riverscape approach has significant conservation potential.     

黄河流域传统果园发展现状及旅游发展潜力分析

全国重要农业文化遗产系统构成了令人叹为观止的优美人文景观,展现着传统农业生态多样性、生态系统适应性和珍贵的文化遗产。这些世代相传的农业系统构成了当代和未来农业创新和技术的基石。已公布的37个传统果园类全国重要农业文化遗产地,有14个沿黄河流域分布,是我国果业重要的发源地。拟以黄河流域的传统果园为研究对象,系统梳理其发展历史、现状及传统果园农耕系统,同时重点分析黄河流域主要果品的区位发展优劣势,最后结合传统果园的人文价值和区域经济发展因素等,综合探索传统果园的传承和利用途径,为我国果业发展提供传统农业系统和技术创新基础,也为传统果园的保护和传承发展以及农业管理部门挖掘和健全果园文化遗产保护机制提供参考。     

岷江上游干旱河谷葡萄栽培的土壤适宜性研究

 研究结果表明，在本区气候生态适宜的前提下，本区的土壤条件亦能确保鲜食和酿酒葡萄优质高产。运用叶片分析与土壤分析相结合诊断土壤对葡萄的养分供应，葡萄叶片的养分含量主要与品种特性有关，也因土壤条件而异，但又具有“中低氮、高中磷和高钾”的总体营养组合特征,同时铁、锌营养大多不足。这大致与供试土壤部分供氮不足、大部磷、钾丰富的状况相对应。此外,土壤pH、质地、土层 厚度等基本能满足葡萄建园的要求。因此葡萄园应根据不同品种和土壤，实施诊断、平衡施肥，同时注意 坡土的水土保持和改良培肥。     

Land-use and land-cover change processes in the Upper Uruguay Basin: linking environmental and socioeconomic variables

Landscape Ecology - Land-use and land-cover change affects both ecological and socioeconomic processes, motivating the integration of environmental and socioeconomic data to help understand this...     

江淮地区乌塌菜品种比较试验

对江淮地区12个乌塌菜品种的形态特性、生长情况及产量等指标进行了观察比较和统计分析,以期筛选出适合江淮地区栽培的优良品种.结果表明:“塌地乌2号”和“塌地乌8号”综合表现最佳,生长势强、株型美观、生长整齐、较耐抽薹、产量高,适宜在江淮流域种植推广.     

黄河上游地区节水减氮对设施越冬芹菜生长发育及产量的影响

以芹菜为试材,在黄河上游地区研究了灌水量、施用氮肥等节水减氮技术对芹菜生长发育及产量的影响,以期为温室芹菜高产、优质、高效栽培及节水灌溉提供科学依据。结果表明:节水减氮对西芹产量的影响达到显著水平;品质方面,总糖含量变化、糖酸化变化受施氮量影响较大,而维生素C含量变化受灌水量影响较为明显,叶绿素含量变化受施氮量影响明显,性能指数则受灌水量变化影响较大。     

长江流域设施蔬菜害虫的发生与防控现状

对长江流域设施蔬菜害虫的发生特点和防控现状进行了概述。长江流域设施蔬菜的害虫发生具有种类多、优势种类明显、发生为害时间提早或为害期延长、抗药性问题突出等特点。当前,长江流域设施蔬菜害虫防治依赖于化学手段。笔者认为,因地制宜建立设施蔬菜害虫绿色防控技术模式、加强设施蔬菜害虫识别和绿色防控技术的培训、发挥植保专业化服务和农药经销从业人员的作用等,是提升长江流域设施蔬菜害虫防控水平、实现设施蔬菜化学农药减施的可行途径。     

Spatial scaling of core and dominant forest cover in the Upper Mississippi and Illinois River floodplains, USA

Different organisms respond to spatial structure in different terms and across different spatial scales. As a consequence, efforts to reverse habitat loss and fragmentation through strategic habitat restoration ought to account for the different habitat density and scale requirements of various taxonomic groups. Here, we estimated the local density of floodplain forest surrounding each of ~20 million 10-m forested pixels of the Upper Mississippi and Illinois River floodplains by using moving windows of multiple sizes (1?C100 ha). We further identified forest pixels that met two local density thresholds: ??core?? forest pixels were nested in a 100% (unfragmented) forested window and ??dominant?? forest pixels were those nested in a >60% forested window. Finally, we fit two scaling functions to declines in the proportion of forest cover meeting these criteria with increasing window length for 107 management-relevant focal areas: a power function (i.e. self-similar, fractal-like scaling) and an exponential decay function (fractal dimension depends on scale). The exponential decay function consistently explained more variation in changes to the proportion of forest meeting both the ??core?? and ??dominant?? criteria with increasing window length than did the power function, suggesting that elevation, soil type, hydrology, and human land use constrain these forest types to a limited range of scales. To examine these scales, we transformed the decay constants to measures of the distance at which the probability of forest meeting the ??core?? and ??dominant?? criteria was cut in half (S _1/2, m). S _1/2 for core forest was typically between ~55 and ~95 m depending on location along the river, indicating that core forest cover is restricted to extremely fine scales. In contrast, half of all dominant forest cover was lost at scales that were typically between ~525 and 750 m, but S _1/2 was as long as 1,800 m. S _1/2 is a simple measure that (1) condenses information derived from multi-scale analyses, (2) allows for comparisons of the amount of forest habitat available to species with different habitat density and scale requirements, and (3) can be used as an index of the spatial continuity of habitat types that do not scale fractally.     

长江流域塑料大棚紫苏栽培技术

紫苏又名赤苏、白苏、青苏、香苏等,为唇形科紫苏属一年生草本植物。原产于中国,在我国各地都有野生种发现,目前在东亚和东南亚大部分国家和地区都有分布,以中国、日本和韩国栽培较为普遍。紫苏嫩叶营养丰富,据测定,每100 g紫苏嫩叶含粗蛋白3.84 g、粗脂肪1.30 g、粗纤维6.96 g、维生素C 68 mg、硫胺素0.02 mg、核黄素0.35 mg、尼克酸1.3 mg、类胡萝卜素9.09 mg、钾522 mg、钙217 mg、镁70.4 mg、磷44 mg、钠4.24 mg、铁20.7 mg、锰1.25 mg、铜0.34 mg、锌1.21 mg、锶1.50 mg、硒3.24μg,此外,还含有具特异芳香味的紫苏醛、紫苏醇、薄荷酮、薄荷醇、丁香油酚、白苏烯酮等物质。