Contrasting trends of butterfly species preferring semi-natural grasslands,field margins and forest edges in northern Europe

Indicator classifications help us to focus on the most relevant groups of species in monitoring the effects of land use changes on biodiversity. We studied changes in distribution area of 74 butterfly species preferring one of the three common habitats of boreal agricultural landscapes: semi-natural grasslands (35 species), arable field margins (7) and forest edges (32). Using extensive atlas data from four time periods during the last 50 years in Finland, we quantified trends in the occupancy of the species in 10 km grid squares, and classified them into four classes: declining (23), stable (17), increasing (27) and fluctuating (7) species. Trends among the species favouring three habitats were different: 60% of the species of semi-natural grasslands had declined, whereas 86% of the species typical of open field margins had increased. An increase also predominated in species associated with forest edges. Declining and increasing species differed in three ecological characteristics: increasing species were more mobile, utilized a wider range of habitats and, based on their larval host plants, lived in more eutrophic habitats than declining species. Species overwintering as adults showed more positive trends in occupancy than species overwintering as eggs, larvae or pupae. Observed trends in occupancy are in good agreement with long-term changes in land use and habitat availability in Finland: a long-continued decrease in the area of semi-natural grasslands and an increased amount of open forest edges and clearings due to modern forestry during the past 50 years.     

The distribution of ecological species groups in Fagetum communities of Caspian forests: Determination of effective environmental factors

Aim of the research was the recognition of ecological species groups in beech forests south of the Caspian Sea (Northern Iran) and the determination of the main effective environmental factors explaining the distribution of plant ecological groups. Selective stratification sampling was used to locate samples. A total of 120 samples (400 m² each) were selected in Fagetum communities within the study area. At each sample, a floristic list of the plot and an estimate of percent cover and abundance of all vascular plants were recorded in separate strata using the Braun-Blanquet scale. At the center of each vegetation plot, two soil samples were taken of 0–10 and 10–30 cm depth levels for physico-chemical analyses. Cluster analysis was used for the classification of vegetation samples and Multi-response Permutation Procedure (MRPP) was used to test the hypothesis of no difference between ecological groups in the species space. Indicator species analysis was used to identify indicator species for each group. A Tukey test was used to compare environmental variables among groups. Detrended Correspondence Analysis (DCA) was used to analyze the relationships between the ecological groups and environmental variables.     

Segregation,nestedness and homogenisation in plant communities dominated by native and alien species

ABSTRACT

Background: Highly modified landscapes offer the opportunity to assess how environmental factors influence the integration of alien plant species into native vegetation communities and determine the vulnerability of different communities to invasion.

Aims: To examine the importance of biotic and abiotic drivers in determining whether alien plant species segregate spatially from native plant communities or become integrated and lead to biotic homogenisation.

Methods: Ordination and classification of a floristic survey of over 1200 systematically located 6 m × 6 m plots were used to examine how plant community segregation, nestedness and homogenisation varied in relation to climate, environmental and human-related factors across Banks Peninsula, New Zealand.

Results: The analyses of community structure indicated that native and alien plant communities were spatially and ecologically segregated due to different responses primarily to an anthropogenic impact gradient and secondly to environmental factors along an elevation gradient. Human-land use appeared most strongly linked to the distribution of alien species and was associated with increased vegetation homogenisation. However, despite spatial segregation of alien and native plant communities, biotic homogenisation not only occurred in highly managed grasslands but also in relatively less managed shrublands and forest.

Conclusions: The role played by anthropogenic factors in shaping alien and native plant species community structure should not be ignored and, even along a marked environmental gradient, if the recipient sites have a long history of human-related disturbance, biotic homogenisation is often strong.     

Base-cation Cycling by Individual Tree Species in Old-growth Forests of Upper Michigan,USA

The influence of individual tree species on base-cation (Ca, Mg, K, Na) distribution and cycling was examined in sugar maple (Acer saccharum Marsh.), basswood (Tilia americana L.), and hemlock (Tsuga canadensis L.) in old-growth northern hardwood – hemlock forests on a sandy, mixed, frigid, Typic Haplorthod over two growing seasons in northwestern Michigan. Base cations in biomass, forest floor, and mineral soil (0–15 cm and 15–40 cm) pools were estimated for five replicated trees of each species; measured fluxes included bulk precipitation, throughfall, stemflow, litterfall, forest-floor leachate, mineralization + weathering, shallow-soil leachate, and deep-soil leachate. The three species differed in where base cations had accumulated within the single-tree ecosystems. Within these three single-tree ecosystems, the greatest quantity of base cations in woody biomass was found in sugar maple, whereas hemlock and basswood displayed the greatest amount in the upper 40 cm of mineral soil. Base-cation pools were ranked: sugar maple > basswood, hemlock in woody biomass; sugar maple, basswood > hemlock in foliage; hemlock > sugar maple, basswood in the forest floor, and basswood > sugar maple, hemlock in the mineral soil. Base-cation fluxes in throughfall, stemflow, the forest-floor leachate, and the deep-soil leachate (2000 only) were ranked: basswood > sugar maple > hemlock. Our measurements suggest that species-related differences in nutrient cycling are sufficient to produce significant differences in base-cation contents of the soil over short time intervals (<65 years). Moreover, these species-mediated differences may be important controls over the spatial pattern and edaphic processes of northern hardwood-hemlock ecosystems in the upper Great Lakes region.     

Habitat availability for multiple avian species under modeled alternative conservation scenarios in the Two Hearted River watershed in Michigan,USA

Due to differences in the responses of species to changing landscape patterns, developing a conservation plan with an optimal outcome of supporting contrasting habitat needs can be difficult. Landscape scenario modeling can provide a means to compare alternative conservation strategies and can reveal tradeoffs of managing for one objective versus another. In order to evaluate the impacts of alternative conservation strategies in a 53,653 ha landscape in Michigan's Upper Peninsula, four scenarios of alternative conservation strategies were modeled 100 years into the future using the VDDT^®/TELSA^® spatial model suite, and habitat availability was evaluated for five target bird species of local conservation concern under each scenario. The target species were Dendroica fusca (Blackburnian Warbler), Picoides arcticus (Black-backed Woodpecker), Dendroica kirtlandii (Kirtland's Warbler), Buteo lineatus (Red-shouldered Hawk), and Scolopax minor (American Woodcock). Scenarios were ranked based on relative performance of three habitat metric results (total primary habitat area, average size of habitat patches, and average distance to the nearest neighboring habitat patch) for each species. The final overall rank for each scenario was generally related to harvest intensity; the scenario with the smallest total area of even-aged management ranked the highest. Ranks were not consistent across all response variables. Relative species sensitivity was also evaluated, and the ranks did not match expectations, with the more habitat generalist species showing the highest sensitivity and the most specialist species showing the lowest. The approach here provides a means of projecting and comparing potential long-term impacts of alternative landscape strategies on diverse wildlife habitats. These results, when considered with budget considerations and species’ habitat area and population goals, can assist local managers and stakeholders in conservation planning by identifying tradeoffs and compromises aimed at optimizing protection for a variety of target species.     

Functional groups of lagoon fish species in Languedoc Roussillon, southern France

Ten functional traits of fish species were related to habitat, diet or food acquisition, to propose a classification of 21 lagoon fishes into 10 functional groups. The selection of traits was based on their functional interest and the ease of measurement. Some groups were taxonomically related containing species belonging to the same genus, e.g . Syngnathus , Atherina or Pomatochistus . Species with a flat body shape constituted another group and three species ( Anguilla anguilla , Gambusia affinis and Callionymus pusillus ) formed individual groups. These results could be used to constitute functional units and to simplify such complex ecosystems and their interactions.     

A spatially interactive simulation of climate change, harvesting, wind, and tree species migration and projected changes to forest composition and biomass in northern Wisconsin, USA

In the coming century, forecast climate changes caused by increasing greenhouse gases may produce dramatic shifts in tree species distributions and the rates at which individual tree species sequester carbon or release carbon back to the atmosphere. The species composition and carbon storage capacity of northern Wisconsin (USA) forests are expected to change significantly as a result. Projected temperature changes are relatively large (up to a 5.8°C increase in mean annual temperature) and these forests encompass a broad ecotone that may be particularly sensitive to climate change. Our objective was to estimate the combined effects of climate change, common disturbances, and species migrations on regional forests using spatially interactive simulations. Multiple scenarios were simulated for 200 years to estimate aboveground live biomass and tree species composition. We used a spatially interactive forest landscape model (LANDIS‐II) that includes individual tree species, biomass accumulation and decomposition, windthrow, harvesting, and seed dispersal. We used data from two global circulation models, the Hadley Climate Centre (version 2) and the Canadian Climate Center (version 1) to generate transient growth and decomposition parameters for 23 species. The two climate change scenarios were compared with a control scenario of continuing current climate conditions. The results demonstrate how important spatially interactive processes will affect the aboveground live biomass and species composition of northern Wisconsin forests. Forest composition, including species richness, is strongly affected by harvesting, windthrow, and climate change, although five northern species (Abies balsamea, Betula papyrifera, Picea glauca, Pinus banksiana, P. resinosa) are lost in both climate scenarios regardless of disturbance scenario. Changes in aboveground live biomass over time are nonlinear and vary among ecoregions. Aboveground live biomass will be significantly reduced because of species dispersal and migration limitations. The expected shift towards southern oaks and hickory is delayed because of seed dispersal limitations.     

Effects of fluvial geomorphology on riparian tree species in Rekifune River,northern Japan

Classification of riverbed geomorphic surfaces based on flooding frequency was conducted and the relationship between their distribution and river morphology was analyzed, to provide an understanding of the structure and species composition of riparian forests dominated by Chosenia arbutifolia. The channel floors of two contrasting river morphologies (bar-braided and incised meandering channels), were divided into five geomorphic surfaces (gravel bar, lower and upper floodplains, secondary channel, and terrace) based on the water level of a 2-yr and a 20-yr recurrence interval. The environmental variables of the same geomorphic surfaces showed similar trends regardless of braided and meandering channel morphology, but differed significantly among the five geomorphic surfaces, which influenced the dominance of tree species. The geomorphic surface map based on recurrence interval of flood and physiognomical vegetation map based on aerial photos appeared almost identical. Geomorphic surface distribution, determined by river channel dynamics and the sediment transport processes occurring at a larger scale and a longer time frame, played an important role in shaping the structure and composition of the riparian forests. C. arbutifolia dominated gravel bar, and the upper and lower floodplains, because these geomorphic surfaces were characterized by gravelly soils which have lower soil moisture availability than soils of other geomorphic surfaces. Thus, an extensive distribution of C. arbutifolia in the braided channel section can be attributed to the frequent lateral migrations of river channels, which resulted in a high ratio of gravel bars, and lower and upper floodplains. In order to preserve indigenous plant communities in riparian zone, dynamic nature and processes of braided rivers should be maintained.     

Effects of spatial heterogeneity on butterfly species richness in Rocky Mountain National Park, CO, USA

We investigated butterfly responses to plot-level characteristics (plant species richness, vegetation height, and range in NDVI [normalized difference vegetation index]) and spatial heterogeneity in topography and landscape patterns (composition and configuration) at multiple spatial scales. Stratified random sampling was used to collect data on butterfly species richness from seventy-six 20 × 50 m plots. The plant species richness and average vegetation height data were collected from 76 modified-Whittaker plots overlaid on 76 butterfly plots. Spatial heterogeneity around sample plots was quantified by measuring topographic variables and landscape metrics at eight spatial extents (radii of 300, 600 to 2,400 m). The number of butterfly species recorded was strongly positively correlated with plant species richness, proportion of shrubland and mean patch size of shrubland. Patterns in butterfly species richness were negatively correlated with other variables including mean patch size, average vegetation height, elevation, and range in NDVI. The best predictive model selected using Akaike’s Information Criterion corrected for small sample size (AIC_c), explained 62% of the variation in butterfly species richness at the 2,100 m spatial extent. Average vegetation height and mean patch size were among the best predictors of butterfly species richness. The models that included plot-level information and topographic variables explained relatively less variation in butterfly species richness, and were improved significantly after including landscape metrics. Our results suggest that spatial heterogeneity greatly influences patterns in butterfly species richness, and that it should be explicitly considered in conservation and management actions.     

云南高黎贡山北段植物物种多样性的垂直分布格局

在高黎贡山北段沿海拔梯度设置17个样地,采用数量分类,对高黎贡山北段植物群落类型、物种组成和多样性的垂直格局进行了研究.结果表明:(1)随着海拔的升高,森林群落类型由常绿阔叶林(2 000～2 300 m)依次过渡为以阔叶树为主的针阔混交林(2 300～2 600 m)、以针叶树为主的针阔混交林(2 600～3 000 m)和针叶林(3 000～3 100 m);(2)木本植物的物种丰富度随着海拔高度的增加显著下降,而草本植物的物种丰富度则随着海拔高度的增加先下降,然后在林线以上显著上升;(3)木本植物β多样性随着海拔的上升呈单调下降趋势,而草本植物β多样性在中海拔附近区域较低;(4)在植物区系方面,热带亚热带成分所占比例随海拔上升而下降,温带成分、世界分布成分则随着海拔的升高而增加.中国特有分布成分所占比重较小,主要分布在中海拔区域.总体上,温带成分占主导地位.区系平衡点在海拔2100～2200 m.     

Molecular identification and relative abundance of cryptic Lophodermium species in natural populations of Scots pine,Pinus sylvestris L.

The multi-locus phylogenetic species recognition approach and population genetic analysis of Amplified Fragment Length Polymorphism (AFLP) markers were used to delineate Lophodermium taxa inhabiting needles of Scots pine (Pinus sylvestris) in native pinewoods within Scotland. These analyses revealed three major lineages corresponding to the morphological species Lophodermium seditiosum and Lophodermium conigenum, fruiting on broken branches, and Lophodermium pinastri, fruiting on naturally fallen needles. Within L. pinastri three well supported sister clades were found representing cryptic taxa designated L. pinastri I, L. pinastri II, and L. pinastri III. Significant differences in mean growth rate in culture were found among the cryptic taxa. Taxon-specific primers based on ITS sequences were designed and used to classify over 500 Lophodermium isolates, derived from fallen needles of P. sylvestris in three Scottish and one French pinewood site, into the three L. pinastri cryptic taxa. Highly significant differences in the relative abundance of the three taxa were found among the Scottish pinewood sites, and between the French and all of the Scottish sites.     

The influence of herbivory on plant cover and species composition in the Pryor Mountain Wild Horse Range,USA

We investigated the effects of short- and long-term ungulate grazing on plant species cover and composition in arid lowland and more mesic upland communities of the Pryor Mountain Wild Horse Range (PMWHR). Measurements were taken over two years which differed significantly in growing season precipitation. Interannual differences in plant cover were significantly greater than differences between grazed and ungrazed communities. In the arid lowlands total plant cover decreased from 47% in 1993, a relatively wet year, to 29% in 1994, a relatively dry year. In the more mesic uplands total plant cover decreased from 107% in 1993 to 56% in 1994. The magnitude of change in cover was greatest in the grasses, especially for Pseudoroegneria spicata, the most abundant species in the lowland communities, which decreased from 21% cover in 1993 to 11% in 1994. There was not a consistent effect of herbivory on plant cover across sites, but its effects, particularly on the dominant perennial grasses, were conspicuous at some sites. For instance, in the lowlands cover of P. spicata was 3–12% in long-term grazed sites and 9–28% in short- to long-term ungrazed sites. Our study indicates that abiotic factors (e.g., precipitation) are more likely than grazing to affect abundances of key plant species, and hence ecosystem dynamics, in the PMWHR, and that the effects of herbivory are more localized and more prevalent in the lowland grasses than in the other plant functional groups.     

Comparison of fecundity, embryo loss and fatty acid composition of mangrove crab species in sewage contaminated and pristine mangrove habitats in Mozambique

The effects of anthropogenic activities combined with the lack of technical solutions for sewage treatment have lead to serious contamination problems in the coastal ecosystems of East Africa. However, not all contaminants can be considered pollutants. Determining when contamination results in pollution requires not only chemical but also biological measurements. Because benthos integrates conditions over time, macrobenthic organisms are considered good bioindicators to assess local environmental quality. Crabs constitute one of the most important macrofauna taxa in terms of abundance, species richness and biomass in mangrove ecosystems. In the present study, the reproductive potential and quality of Uca annulipes population inhabiting a peri-urban mangrove, subjected to domestic sewage discharges, was compared to populations inhabiting pristine mangroves. Fecundity, egg quality (fatty acids composition) and potential fertility were evaluated and compared by sampling a representative fraction of ovigerous females captured in each of the mangrove habitats at two seasons (February to March, 2006 — wet season; and August to September, 2006 — dry season). Most of the measured reproductive parameters of U. annulipes were different at Maputo peri-urban mangrove when compared to nearby pristine locations. Although we cannot prove that sewage discharge done at Costa do Sol mangrove was the main factor influencing the reproductive dynamics of U. annulipes populations, at this peri-urban mangrove this fiddler crab species extended its reproductive season, increased fecundity, as well as improved embryo quality, mainly regarding the concentration of SFA and MUFA, in relation to the pristine mangrove populations.     

Vascular plant species richness and rarity across a minerotrophic gradient in wetlands of St. Lawrence County,New York,USA

Thirteen wetlands in St. Lawrence County, NY were sampled to examine the effect of a minerotrophic gradient on vascular plant species richness and rarity. Wetlands ranged from organic soil based poor fens (average conductivity 46.40 microsemens, average Ca 3.55 ppm) to mineral soil based rich fens (average conductivity 342.10 microsemens, Ca 23.00 ppm). Vascular plant species richness was sampled during 1990 in randomly located 1.0 m² quadrats. Specific conductivity, presence or absence of hummocks, and water depth predicted 62% of the variation in richness. Richness increased as conductivity increased until 413 microsemens at which a down trend became obvious. The negative curvilinear relation between conductivity and richness is in accordance with the hump-backed model of Grime but occurs at high rather than intermediate conductivity values. State-listed rare species were found in species-rich wetlands only and had a mean associated richness value of 14.50 species m^-2. This relationship should be taken into consideration when selecting wetlands for protection or managing wetlands for maximum plant diversity.     

Climatic and biophysical controls on conifer species distributions in mountain forests of Washington State, USA

Abstract Aim The purpose of this study was to quantify relationships between conifer species distributions and climatic and biophysical variables, in order to provide better insight into the potential for redistribution of species on the landscape in response to climatic change. Location Data are from 10,653 georeferenced sites in Washington State, USA, along a longitudinal gradient from west of the crest of the Cascade Range to the beginnings of the western slope of the Rocky Mountains, and across two physiographic provinces, the Northern Cascades, characterized by steep, rugged topography, and the Okanogan Highlands, presenting moderate slopes and broad rounded summits. Methods Tree data were drawn from the USDA Forest Service Area Ecology Program database, collected in mature, undisturbed stands. We compared simple climatic variables (annual temperature, growing‐degree days, annual and seasonal precipitation) to biophysical variables (soil, hydrologic, and solar radiation) derived from climatic variables. Climatic and biophysical variables were taken from the output of climatological and hydrological simulation models and estimated for each plot in the tree database. Generalized linear models were used, for each of fourteen tree species, at multiple spatial extents, to estimate the probability of occurrence of that species as a function of climatic and biophysical predictors. Models were validated by a combination of bootstrapping and estimating receiver operating characteristic (ROC) curves. Results For the majority of species, we were able to fit variables representing both moisture and temperature gradients, and in all but a few cases these models identified a unimodal response of species occurrence to these gradients. In some cases the ecological/environmental niche of a species had been clearly captured by the model, whereas in others a longer gradient in the predictor variable(s) would be needed. Responses of most species were consistent across three spatial scales. Main conclusions By identifying the ecological niches of multiple species, we can forecast their redistribution on the landscape in response to climatic change, evaluate the predictions of simulation models, and alert managers to particularly sensitive or vulnerable ecosystems and landscapes.     

水坝工程对澜沧江中游陆生植物的生态风险评估

以澜沧江中游小湾水库库周为研究区,在1997年(小湾水库建设前)澜沧江中游小湾水库下游3个样地[输电区(1号样地)、变电站和进站公路区(2号样地)和水库移民区(3号样地)]植被调查基础上,2010年(小湾水库建设后)分别对3个样地进行植被组成、盖度和优势种观测,评估了水坝工程对澜沧江中游陆地植物的生态风险.结果表明:3个样地上优势种的总和优势度在水坝建设前后均发生了明显变化.本研究根据物种类型(优势种和非优势种)及物种总和优势度变率将生态风险划分为无风险/极低风险(0)、低风险(Ⅰ)、中风险(Ⅱ)、高风险(Ⅲ)、极高风险(Ⅳ)5个等级.研究区处于Ⅲ级生态风险(高风险)的物种数量最多,部分物种处于Ⅳ级生态风险(极高风险);3号样地处于Ⅲ级(高风险)和Ⅳ级(极高风险)生态风险的物种比例明显高于l、2号样地.水坝建设导致的物种水平生态风险主要表现为原生物种减少、外来物种大量入侵等.应采取有效的保护措施降低陆生植物物种水平水坝生态风险.