Landscape drivers of connectivity for a forest rodent in a coffee agroecosystem

Landscape Ecology - The majority of remaining tropical forests exist as fragments embedded in a matrix of agricultural production. Understanding the effects of these agricultural landscapes on...     

Landscape diversity and field border density enhance carabid diversity in adjacent grasslands and cereal fields

Landscape Ecology - Permanent grasslands have declined across Europe since the agricultural intensification. Grassland vicinity, landscape heterogeneity and vicinity of hedgerows are enhancing...     

Landscape variables impact the structure and composition of butterfly assemblages along an urbanization gradient

How urbanization affects the distribution patterns of butterflies is still poorly known. Here we investigated the structure and composition of butterfly assemblages along an urbanization gradient within the most urbanized and densely populated region in France (Île-de-France). Using a method issued from artificial neural networks, i.e. self-organizing maps (SOMs), we showed the existence of four typical assemblages ranging from urban-tolerant species to urban-avoider species. We identified indicator species of these assemblages: the peacock butterfly (Inachis io) in urbanized areas, the swallowtail (Papilio machaon) in sites with intermediate human pressure, or the meadow brown (Maniola jurtina), the small heath (Coenonympha pamphilus) and the gatekeeper (Pyronia tithonus) in meadows around Paris. A discriminant analysis showed that the four assemblages were mainly segregated by landscape elements, both by structural variables (habitat type, proportion of rural areas and artificial urban areas, patch surface) and functional variables (distance to the nearest wood, artificial area and park). Artificial neural networks and SOMs coupled stepwise discriminant analysis proved to be promising tools that should be added to the toolbox of community and spatial ecologists.     

Landscape patterns and diversity of meadow plants and flower-visitors in a mountain landscape

Context

Wild flowering plants and their wild insect visitors are of great importance for pollination. Montane meadows are biodiversity hotspots for flowering plants and pollinators, but they are contracting due to tree invasion.

Objectives

This study quantified flowering plants and their flower-visitor species in montane meadows in the western Cascade Range of Oregon. Species diversity in small, isolated meadows was expected to be lower and nested relative to large meadows. Alternatively, landform features may influence richness and spatial turnover.

Methods

Flowering plants and their visitors were sampled in summers of 2011–2017 in twelve montane meadows with varying soil moisture. All flowering plants and all flower-visitors were recorded during five to seven 15 min watches in ten 3?×?3 m plots in each meadow and year.

Results

A total of 178 flowering plant species, 688 flower-visitor species and 137,916 interactions were identified. Richness of flower-visitors was related to meadow patch size, but neither plant nor flower-visitor richness was related to isolation measured as meadow area within 1000 m. Species in small meadows were not nested subsets of those in large meadows. Species replacement accounted for more than 78% of dissimilarity between meadows and was positively related to differences in soil moisture.

Conclusions

Although larger meadows contained more species, landform features have influenced meadow configuration, persistence, and soil moisture, contributing to high plant and insect species diversity. Hence, conservation and restoration of a variety of meadow types may promote landscape diversity of wild plants and pollinators.

     

发展户用沼气 构建和谐农村

1、发展户用沼气,构建和谐农村1．1发展农村沼气是农业增效、农民增收的有效途径 沼气建设是一项投资少、见效快,一次投资多年受益的利国利民工程。一个8—10m3的沼气池能够满足一个4—5口之家生活用能,每户每年可节约煤款600元,节约电费100元t每户养猪4头以上,一年出栏2次,共出栏8头以上,每头猪纯收入按100元计,仅养猪一项可增收800余元,沼液、沼渣是高效有机肥,     

Landscape context of rural residential development in southeastern Wisconsin (USA)

Private on-site sewage systems serve residential development in rural landscapes throughout the United States. In the State of Wisconsin, three major types of private sewage systems facilitate residential development on sites that span gradients in slope, soil permeability, depth to bedrock, and depth to water-table. Conventional soil-absorption sewage treatment systems are constructed on sites with minimal physiographic constraints; more highly engineered alternative sewage treatment systems are installed on sites with moderate to severe constraints; holding tanks provide no on-site sewage treatment and are employed on sites with the most severe physiographic limitations. An environmental impact statement (EIS), prepared in 1979 on the proposed widespread use of alternative private sewage systems, suggested that alternative systems might facilitate in-fill development on poor sites near existing cities and lead to compact, higher density development patterns.The research reported in this paper tested the validity of this EIS scenario by comparing development patterns associated with a sample of conventional systems, alternative systems, and holding tanks installed during the 1980s in Ozaukee County, Wisconsin. Land use data, soils data, and other site attribute data were assembled and analyzed in a vector geographic information system (GIS). Because each type of private sewage system has a unique set of siting criteria, the three sets of sampled systems are located in significantly different physiographic regions within the County. Collectively, installations of all three systems facilitated scattered residential development throughout the rural landscape. This development consists of relatively small residential patches dispersed within an agricultural matrix. Wastewater management technology, if not constrained by public policies or other socioeconomic factors, can be an important anthropogenic factor influencing both the process and pattern of landscape change.     

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.     

Landscape history,time lags and drivers of change: urban natural grassland remnants in Potchefstroom,South Africa

Context

The history of the landscape directly affects biotic assemblages, resulting in time lags in species response to disturbances. In highly fragmented environments, this phenomenon often causes extinction debts. However, few studies have been carried out in urban settings.

Objectives

To determine if there are time lags in the response of temperate natural grasslands to urbanization. Does it differ for indigenous species and for species indicative of disturbance and between woody and open grasslands? Do these time lags change over time? What are the potential landscape factors driving these changes? What are the corresponding vegetation changes?

Methods

In 1995 and 2012 vegetation sampling was carried out in 43 urban grassland sites. We calculated six urbanization and landscape measures in a 500 m buffer area surrounding each site for 1938, 1961, 1970, 1994, 1999, 2006, and 2010. We used generalized linear models and model selection to determine which time period best predicted the contemporary species richness patterns.

Results

Woody grasslands showed time lags of 20–40 years. Contemporary open grassland communities were, generally, associated with more contemporary landscapes. Altitude and road network density of natural areas were the most frequent predictors of species richness. The importance of the predictors changed between the different models. Species richness, specifically, indigenous herbaceous species, declined from 1995 to 2012.

Conclusions

The history of urbanization affects contemporary urban vegetation assemblages. This indicates potential extinction debts, which have important consequences for biodiversity conservation planning and sustainable future scenarios.

     

Landscape and local correlates with anuran taxonomic,functional and phylogenetic diversity in rice crops

Context

Deforestation is a major driver of biodiversity loss, mainly due to agriculture. As rice is among the world’s most important crops, determining how agricultural communities are shaped is imperative. However, few studies have addressed the factors that alter community assembly in human-modified landscapes. We aim to quantify taxonomic, functional, trait and phylogenetic diversity of an anuran community from rice crops on a biodiversity hotspot.

Objectives

Identify local and landscape characteristics responsible for variations in multiple dimensions of anuran diversity in rice crops.

Methods

This study was performed in Tocantins, Brazil. We chose 36 lentic waterbodies on rice fields for anuran sampling. We quantified taxonomic diversity (TD), functional diversity (FD) and phylogenetic diversity (PD) for each waterbody. We also estimated the mean functional differences among species for each trait separately. To evaluate how local and landscape scale features affect anurans, we performed generalized linear mixed models in 500, 1000 and 1500 m buffers around each waterbody.

Results

We found increased PD and FD in waterbodies closer to many other waterbodies and large forest patches. Anuran biomass decreased with increasing distance to the closest waterbody. Trait diversity varied with waterbody abundance and closeness, percentage of bare ground and marginal vegetation.

Conclusions

Our study emphasizes the importance of waterbody and forest patch networks for maintaining high anuran FD and PD in agricultural landscapes. As both metrics are known to be related to ecosystem resilience, understanding these patterns is pivotal for biodiversity management, especially in the tropics, where agricultural expansion is unrelenting and biodiversity is especially unique.

     

Landscape composition is the major driver of the taxonomic and functional diversity of tropical frugivorous birds

Landscape Ecology - Anthropogenic land use and cover changes impact biodiversity worldwide. However, ecological groups are differently affected by landscape composition and configuration....     

Landscape patch shape complexity as an effective measure for plant species richness in rural landscapes

The application of landscape patch shape complexity as a predictor ofvascularplant and bryophyte species richness is analysed. Several common complexityindices (shape index, fractal dimension, comparison to the area of the minimumbounding rectangle) are tested for their predictive power for plant speciesrichness. One new robust measure for shape complexity is presented whichovercomes some disadvantages of common complexity measures applied to highresolution analysis of agricultural landscapes based on aerial photographs. Thenew index is based on the number of shape characterising points along apolygons boundary. This new measure shows promising predictive capabilitiesforspecies richness of vascular plants and bryophytes (correlation coefficient:0.85 for vascular plants, 0.74 for bryophytes).This revised version was published online in May 2005 with corrections to the Cover Date.     

Landscape configuration of an Amazonian island-like ecosystem drives population structure and genetic diversity of a habitat-specialist bird

Landscape Ecology - Amazonian white-sand ecosystems (campinas) are open vegetation patches which form a natural island-like system in a matrix of tropical rainforest. Due to a clear distinction...     

三种杀虫剂对梨小食心虫和桃小食心虫的残效研究

【目的】了解氯虫苯甲酰胺、氟虫双酰胺和灭幼脲对梨小食心虫和桃小食心虫的直接致死效果及对后续各虫态发育的影响。【方法】采用浸渍法,用3种杀虫剂分别处理2种食心虫的卵和老熟幼虫。【结果】氟虫双酰胺200 mg·kg-1和氯虫苯甲酰胺50 mg·kg-1、25 mg·kg-1虽能显著降低梨小食心虫卵孵化率,但幅度较小。各药剂浓度处理均可显著提高初孵幼虫死亡率。3种药剂基本不影响桃小食心虫卵孵化,但灭幼脲和氟虫双酰胺各浓度处理可显著提高初孵幼虫死亡率。氯虫苯甲酰胺降低了梨小食心虫的化蛹率、成虫羽化率,对F1代卵的孵化也有抑制作用。灭幼脲只影响处理当代虫的发育变态,对F1代卵孵化没有影响。除氯虫苯甲酰胺25 mg·kg-1处理外,其他药剂处理均可抑制桃小食心虫幼虫化蛹。所有试验药剂处理均显著抑制桃小食心虫的成虫羽化和产卵,其中氟虫双酰胺200 mg·kg-1、灭幼脲200mg·kg-1和100 mg·kg-1处理的桃小食心虫均不能产卵。【结论】综合以上试验结果,认为氟虫双酰胺、氯虫苯甲酰胺和灭幼脲对2种食心虫的初孵幼虫具有高杀虫活性;虽然对老熟幼虫直接致死效果低,但可以抑制其发育变态及繁殖,缓慢降低种群数量,起到控制害虫的效果。因此,在生产上使用上述3种杀虫剂防治梨小食心虫和桃小食心虫时,建议在卵期和幼虫脱果期喷药,便于及时控制食心虫危害。     

色彩景观在香草植物专类园规划设计中的应用

色彩景观在现代园林空间和植物景观的营造中起到了重要作用。色彩的冷暖及其产生的心理感受可以改变园林空间的大小,而合理运用植物色彩的互补、邻近、类似色调,可以达到丰富多样的景观效果。在香草植物专类园的设计实例中,以视觉和嗅觉感官体验为特色,将园林景观要素的色彩、体量、肌理等合理规划,营造景色怡人的大地景观。     

食用菌产业推动农村三产融合发展的现状分析

乡村振兴战略作为新时代"三农"工作总抓手,产业兴旺被列为第一个目标,在实现产业兴旺的过程中,需要深入推动农村三产融合,促进农业转型升级和农村生态环境保护。通过分析2004—2019年中国食用菌产量、产值,以及2019年中国食用菌分品种(按大类统计)进出口数据,初步了解中国食用菌产业发展现状,发现中国食用菌产业在推动农村三产融合的过程中存在整体技术水平不高、产业投资存在一定盲目性,社会化服务体系不健全等问题。提出培育农村三产融合新型经营主体,不断激发市场活力;发掘农村发展内生动力,加强农村三产融合;开启"政企农共建"模式,增强农村产业融合社会化服务等新路径,以促进我国食用菌产业健康有序发展,在三产融合过程中发挥更大作用。     

Landscape prerequisites for the survival of a modelled metapopulation and its neutral genetic diversity are affected by climate change

In response to climate change a species may move, adapt, or go extinct. For the adaptability of a population its genetic diversity is essential, but climate change-induced range shifts can cause a loss of genetic diversity. We investigated how landscape structure affects the level and distribution of genetic diversity in metapopulations subject to climate change-induced range shifts. For this we used the spatially explicit, individual-based model METAPHOR which simulates metapopulation demography and genetics under different temperature increase scenarios. The results indicated that increasing total habitat area may enhance the maintenance of the genetic diversity in metapopulations while they are shifting their range under climate change. However, the results also showed that a high level of total habitat area did not prevent the populations in the newly colonised habitat area of being depleted of much of the original genetic diversity. We therefore conclude that enhancing landscape connectivity may lead to a delayed loss of genetic diversity in metapopulations under climate change, but that additional measures would be necessary to ensure its long-term conservation. Importantly, our simulations also show that a landscape which could be regarded as well-structured under stable climatic conditions, may be inferior for the conservation of genetic diversity during a range shift. This is important information for landscape management when developing strategies for the in situ conservation of genetic variation in natural populations under climate change.     

Landscape dynamics and equilibrium in areas of slash-and-burn agriculture with short and long fallow period (Bragantina region,NE Brazilian Amazon)

Fallow periods used in slash-and-burn agriculture in the Bragantinaregion, the oldest agricultural frontier in the Brazilian Amazon, are beingreduced. The objective of this study was to analyze the effects of a shortenedfallow period on the Bragantina landscape dynamics and equilibrium. Dynamicswere characterized by landscape structural changes, particularly in the spatialdistribution of secondary forests, and by transition matrix. Equilibrium wasdefined by temporal and spatial parameters, and by the increment ofagriculturalareas from 1985 to 1996, analyzed with 6 LANDSAT-TM images. I worked with 6areas of 250 ha each, 3 with short fallow periods (2–4years)and 3 with long fallow periods (about 10 years). Results showed that shortfallow period areas did not present an equilibrium situation. In these areas,developed secondary vegetation tended to disappear and agricultural areas werebeing expanded at an average rate of 3% per year. Landscape structure changespointed out that a reduction in fallow period was occurring in already shortfallow period areas. Long fallow period areas presented a shifting mosaicsteady-state condition, where punctual changes due to agricultural uses werecompensated by field abandonment rate. Both agricultural uses and fieldabandonment rates were lower in long fallow period areas when compared withshort ones. Comparisons with indigenous traditional cropping-fallow cyclesindicate that sustainable conditions could be maintained with 11 years offallowfor each cropping year, while shorter cycles would break down the system ifagricultural improvements are not implemented.This revised version was published online in May 2005 with corrections to the Cover Date.     

Spatial and temporal organization of macroinvertebrate assemblages in a lowland floodplain ecosystem

An important goal in ecology is to understand controls on community structure in spatially and temporally heterogeneous landscapes, a challenge for which riverine floodplains provide ideal laboratories. We evaluated how spatial position, local habitat features, and seasonal flooding interact to shape aquatic invertebrate community composition in an unregulated riverine floodplain in western Alabama (USA). We quantified sediment invertebrate assemblages and habitat variables at 23 sites over a 15-month period. Dissolved oxygen (DO) varied seasonally and among habitats, with sites less connected to the river channel experiencing frequent hypoxia (<2 mg O₂ L^?1) at the sediment–water interface. Differences in water temperature among sites were lowest (<1 °C) during winter floodplain inundation, but increased to >14 °C during spring and summer as sites became isolated. Overall, local habitat conditions were more important in explaining patterns in assemblage structure than was spatial position in the floodplain (e.g., distance to the main river channel). DO was an important predictor of taxonomic richness among sites, which was highest where hydrologic connections to the main river channel were strongest. Compositional heterogeneity across the floodplain was lowest immediately following inundation and increased as individual sites became hydrologically isolated. Our results illustrate how geomorphic structure and seasonal flooding interact to shape floodplain aquatic assemblages. The flood pulse of lowland rivers influences biodiversity through effects of connectivity on hydrologic flushing in different floodplain habitats, which may prevent the development of harsh environmental conditions that exclude certain taxa. Such interactions highlight the ongoing consequences of river regulation for taxonomically diverse floodplain ecosystems.     

Response of snails and slugs to fragmentation of lowland forests in NW Germany

Habitat fragmentation is a major cause for species loss, but its effect on invertebrates with low active dispersal power, like terrestrial gastropods, has rarely been studied. Such species can not cross a hostile habitat matrix, for which the predictions of island theory, such as positive relations between species richness and patch size, should apply. In order to test this prediction, we studied gastropod species diversity by assessing gastropod assemblage characteristics from 35 sites in 19 fragments of deciduous old-growth forests in the Lower Rhine Embayment, Germany. Assemblages differed between larger (≥700 ha) and smaller forests (<400 ha), those of large forests held a higher percentage of forest species. Although α-diversity was similar between the two forest size classes, small forests often comprised matrix species, resulting in a higher β-diversity. Edge effects on the species richness of matrix species were noticeable up to 250 m into the forest. Hierarchical partitioning revealed that distance to disturbances (external edge, internal edges like roads) explained most assemblage variables, whereas forest size and woodland cover within a 1 km radius from the sites explained only a few assemblage variables. Densities of two forest-associated species, Discus rotundatus and Arion fuscus, decreased with forest size. Yet, forest size was positively correlated with richness of typical forest species and densities of Limax cinereoniger. The latter species seems to need forests of >1,000 ha, i.e., well above the size of most fragments. In conclusion, the prediction is valid only for forest species. The response to fragmentation is species specific and seems to depend on habitat specialization and macroclimatic conditions. Jean-Pierre Maelfait: Deceased.