Effect of landscape context on anuran communities in breeding ponds in the National Capital Region,Canada

Land cover change, predominantly habitat conversion to agricultural use and urbanization, has recently been recognized as the primary cause of biodiversity loss in terrestrial ecosystems. We evaluated the relative effects of urban and agricultural landscapes on anuran species richness and the abundance of six anuran species found at breeding ponds in and around the cities of Ottawa, Ontario and Gatineau, Quebec. We performed six call surveys at 29 permanent focal ponds surrounded by one of three landscape contexts: primarily urban, primarily agricultural, and primarily forested. We also measured three local pond variables to control for the effects of local habitat quality in our analyses. We found that anuran species richness was significantly lower in breeding ponds in urban landscapes compared to forested and agricultural landscapes, which exhibited no significant difference in species richness. The abundances of individual anuran species were also consistently lower in urban landscapes for all species except one, which exhibited no response to landscape type. Three species had their highest abundances in ponds in forested landscapes, whereas two species had their highest abundances in ponds in agricultural landscapes. We conclude that ponds embedded in urban landscapes support lower biodiversity than ponds in agricultural settings. We suggest that landscapes composed of a mosaic of forest and open habitats surrounding wetlands would hold the highest biodiversity of these species.     

Species diversity of urban forests in China

A good knowledge of species diversity is essential for urban forest planning and management. In this study, we analyzed species diversity of urban forests in China using data synthesized through a systematic review. Our analysis showed that 3740 taxa of woody plants at species level and below have been reported in urban forests in 257 cities. Merging to the species level, there were 2640 species, including 1671 trees, 743 shrubs, and 226 lianas. Salix babylonica L. was the most widely distributed urban tree species in China. Overall, native species accounted for 76.02% of the observed species while the rest were exotic species. Inside cities, parks contained more species than other types of land use. Among cities, composition similarity of urban forests decreased as spatial distances among them increased. Besides, there was a latitudinal pattern in compositional similarity of urban forests in China. The relatively low ratio of the number of woody plant species in urban forests to these naturally distributed in China indicates that there is plenty of room for increasing species diversity of urban forests in China. However, cautions must be taken to avoid increasing compositional similarity of urban forests in China at the same time.     

Processes of environmental degradation and opportunities for rehabilitation in Adwa,Northern Ethiopia

There are only a few studies of land cover-land use changes which provide an integrated assessment of the biophysical and societal causes and consequences of environmental degradation in Ethiopia. Our objectives were to determine the status of the environmental degradation, analyse and evaluate the relationships among vegetation, geomorphological and socio-economic factors contributing to environmental degradation, and propose opportunities for rehabilitation of these natural resources. Field and other environmental data in northern Ethiopia and those acquired by remote sensing techniques were used to accomplish these objectives. These were integrated with socio-economic data obtained from official sources using a Geographic Information System (GIS).Spatial information such as the percent of land cover-land use types and geomorphological categories, and the percent of each land cover-land use type in the geomorphological categories were calculated using Geographic Information System (GIS). The three most dominant features of the geomorphological categories (93.0%) are scarps and denuded rock slopes, erosion surfaces and badlands, while the three most dominant features in the land cover-land use types (71.3%) are croplands, open woodlands and bushlands. Badlands account for 38.7% of the geomorphological units and 41.8% of the croplands currently occur on badlands. Simple and partial correlation analyses were applied to explore the extent of the interaction between the anthropogenic and the natural system. The anthropogenic system is influenced by elevation, which is positively correlated with human population and livestock densities and area of croplands. The natural system finds its place only on steep slopes as shown by the positive correlation between woodland,slope, high potential erosion, scarps and denudational rock slopes. The study indicates that agriculture in the study area is in a critical environmental situation. A change of paradigm in land-use and development is needed to encourage participation of the landowners and users in the efforts to conserve the vegetation and the soil. This study provides sound options that could be used to rehabilitate the vegetation directly and to alleviate the current pressure on the land and improve human welfare indirectly. Matching the human and livestock densities with the carrying capacity of the land through recruitment of the surplus labour force for a modern economy, resettlement,off-farm employment and intensification of agriculture are t he long and short-term actions that may contribute to the rehabilitation of the degraded areas. This revised version was published online in July 2006 with corrections to the Cover Date.     

青岛八大关园林植物多样性研究

把植物生态学的研究方法应用于园林植物群落,调查分析青岛八大关公共绿地园林植物群落的物种多样性,结果表明:八大关公共绿地有园林植物93种,隶属于42科69个属,其中频度较高的主要是刺槐、紫荆和砂地柏.乔木Margalef丰富度指数平均值为2.05,灌木Margalef丰富度指数平均值为1.36,Shannon-Wienner多样性指数为3.69,Pielou均匀度指数为0.93,可以看出乔木层比灌木层丰富度高,多样性指数相对较高.     

青岛市中山公园木本植物多样性研究

对青岛市中山公园木本植物的群落多样性进行调查研究。结果表明:中山公园有木本植物199种,隶属于55科113属;频度指数最高的为刺槐和朴树,均为62.5%。乔木Margalef丰富度指数均值为1.32,灌木Margalef丰富度指数均值为0.47,乔木和灌木的Shannon-Wienner指数分别为2.39和1.96,乔木层多样性指数高于灌木层。     

Landscape Position, Local Environmental Factors, and the Structure of Molluscan Assemblages of Lakes

Biotic communities are structured by both regional processes (e.g., dispersal) and local environmental conditions (e.g., stress). We examined the relative importance of landscape position (position within the hydrologic flow system and distance from other lakes) and local environmental factors in determining the assemblage structure of lake-dwelling snails and fingernail clams in a boreal landscape. Both landscape position and local environmental factors were highly influential in structuring the molluscan assemblages. In canonical correspondence analysis, 53.6% of snail and 48.2% of fingernail clam assemblage composition were accounted for by both sets of variables. The pure effects of landscape position were higher than those of environmental variables, and a considerable amount of variability was shared by the two sets of variables. In regression analysis, 95.5% of snail and 62.2% of fingernail clam species richness was accounted for by the explanatory variable groups, with most of the variability being related to shared effects, followed by landscape position. The effects of landscape position on species composition suggest that passive dispersal increases the similarity of molluscan assemblages in adjacent lakes. This process does not lead to an overall homogenisation of assemblage composition across the landscape, however, because local conditions set a strong environmental filter, excluding species that arrive at an unsuitable lake. These environmental filters may reflect either extinction probability (area, productivity) or species niche differences (calcium levels, abiotic stress). Landscape position may also be important in maintaining the species richness of lake-dwelling molluscan assemblages. By providing potential colonists, nearby source lakes are likely to be important in countering local extinctions. Our test of the relative importance of landscape position and local drivers of assemblage structure was partly confounded by their co-variation. Nevertheless, studying the relationship between landscape position and local variables is useful because it can tell us about the importance of local and regional processes in shaping lake communities.     

Urban sprawl and its impacts on land use change in Central Ethiopia

This study aimed to understand the major drivers of urban sprawl and its impacts on land use conversion in the peri-urban kebeles of the Dukem town, Central Ethiopia. GIS software was used to create status and location maps of industries out of the GPS data. The results from qualitative data obtained from interviews and focus group discussions showed that more land was used beyond the total size of land allocated initially planned for. Furthermore, urban sprawl has also caused an extensive agricultural land conversion (ALC) that has seriously affected agricultural production. Industrialization, residential expansion and infrastructure development were identified as the leading drivers of ALC that negatively affects the size of cultivated land and food crop production in the hinterlands. In contrast with government policies and community expectations, most converted lands had a very low development status and some of them were underdeveloped and demonstrated leapfrog sprawling.     

北方民族大学校园园林植物配置及其应用

论述了北方民族大学校园园林植物的种类组成和在园林绿化中的应用.结果表明:该校现有园林植物63种,隶属于29科,44属;乔木、灌木和草本植物分别有40种、17种和6种,乔/灌(含草本)比为1∶0.57;常绿植物9种,落叶植物54种,分别占总数的14.3%和85.7%;乡土种36种,引进种27种,分别占总数的57.1%和42.9%.分析了校园绿化工作中存在的问题,并提出了改进建议.     

Variations in land surface temperature and cooling efficiency of green space in rapid urbanization: The case of Fuzhou city,China

Rapid urbanization has caused significant land cover change (LCC) as well as changes in the land surface temperature (LST). However, the crucial land dynamic process, which could significantly contribute to the increase in LST and aggravation of the urban heat island (UHI) effect, remains poorly understood. Additionally, a strategy to optimize the most significant decreased land cover type in order to maximize the cooling effect is still lacking. Therefore, in this study, we selected the rapidly urbanizing and ‘hottest’ city in China, Fuzhou, as a case study. Two algorithms were selected to compare and obtain reliable LST data. A land use transfer matrix was used to detect critical contributions leading to the LST variations. The concept of cooling efficiency (CE) and the threshold value of efficiency (TVoE) are also proposed, defined, and calculated. The results show that LST values increased with increasing proportion of built-up land and sharply decreasing proportion of green space. Areas where LST differences exceed 4 °C cover 93% of the areas where green spaces decreased. Additionally, the LST variation is not only associated with the dominant land cover types but is also affected by the land cover transfer pattern and dynamics. Finally, we have calculated the TVoE of green space in Fuzhou city to be 4.55 ± 0.5 ha. This finding implies that when Fuzhou municipality implements urban/landscape planning, a green space area of 4.55 ± 0.5 ha is the most efficient to reduce the heat effect. This study extends the current understanding of LCC dynamics and LST variation. The concepts of the CE and TVoE are meaningful for landscape planning practice and can be used in other cases.     

几种地被植物光能及水分利用特性研究

采用LI-6400光合系统分析仪,研究了7种地被植物的光合生理生态的日变化。结果表明:萱草和蜘蛛兰的净光合速率日变化曲线为单峰,香叶菖蒲、万年青、鸢尾、花叶玉簪、朱顶红的净光合速率日变化曲线为双峰,表现出明显的"午休"现象,净光合速率日均值大小顺序为蜘蛛兰萱草香叶菖蒲鸢尾花叶玉簪朱顶红万年青;蜘蛛兰、鸢尾、花叶玉簪、万年青、香叶菖蒲的蒸腾速率日变化曲线呈单峰,萱草和朱顶红表现为双峰,蒸腾速率日均值大小顺序为蜘蛛兰萱草花叶玉簪香叶菖蒲鸢尾朱顶红万年青;水分利用效率依次为万年青萱草蜘蛛兰香叶菖蒲鸢尾朱顶红花叶玉簪。光能利用效率依次为蜘蛛兰萱草香叶菖蒲朱顶红鸢尾万年青花叶玉簪。综上可知,生长旺季蜘蛛兰、萱草获取光能能力强,吸收CO2量大,对空气的碳-氧平衡贡献比其它地被植物大。万年青、朱顶红、鸢尾、香叶菖蒲调节水分损失的能力及适应干旱环境的能力较强。     

聊城市区广场树木生长状况与园林植物多样性相关关系的研究

对聊城市广场树木生长状况与园林植物多样性之间的关系进行研究,结果表明:广场树木生长状况的数量化值与用 Shannon-Wiener 指数表示的园林植物多样性之间有良好的相关关系,相关方程为:G=2.7799 1.3056H,相关系数为R=0.9597,估计可靠性P=99.9%.     

Accessibility as a determinant of landscape transformation in western Honduras: linking pattern and process

This study evaluates the relationship between landscape accessibility and land cover change in Western Honduras, and demonstrates how these relationships are influenced by social and economic processes of land use change in the region. The study area presents a complex mosaic of land cover change processes that involve approximately equal amounts of reforestation and deforestation. Landsat Thematic Mapper (TM) satellite imagery of 1987, 1991 and 1996 was used to create three single date classifications and a land cover change image depicting the sequence of changes in land cover between 1987–1991–1996. An accessibility analysis examined land cover change and landscape fragmentation relative to elevation and distance from roads. Between 1987 and 1991, results follow ‘expected’ trends, with more accessible areas experiencing greater deforestation and fragmentation. Between 1991 and 1996 this trend reverses. Increased deforestation is found in areas distant from roads, and at higher elevations; a result of government policies promoting expansion of mountain coffee production for export. A ban on logging, and abandonment of marginally productive agricultural fields due to agricultural intensification in other parts of the landscape, has led to increased regrowth in accessible regions of the landscape. Roads and elevation also present different obstacles in terms of their accessibility, with the smallest patches of cyclical clearing and regrowth, relating mostly to the agricultural fallow cycle, found at the highest elevations but located close to roads. This research highlights the need to locate analyses of land cover change within the context of local socio-economic policies and land use processes. This revised version was published online in August 2006 with corrections to the Cover Date.     

The influence of management history and habitat on plant species richness in a rural hemiboreal landscape,Sweden

We explored patterns of plant species richness at different spatialscales in 14 habitats in a Swedish rural landscape. Effects of physicalconditions, and relationships between species richness and management historyreaching back to the 17^th century were examined, using old cadastralmaps andaerial photographs. The most species-rich habitats were dry open semi-naturalgrasslands, midfield islets and road verges. Alpha diversity (species richnesswithin sites) was highest in habitats on dry substrates (excluding bedrock withsparse pines) and beta diversity (species richness among sites) was highest inmoist to wet habitats. Alpha and beta components of species richness tended tobe inversely related among habitats with similar species richness. Managementhistory influenced diversity patterns. Areas managed as grasslands in the17^th and 18^th century harboured more species than areasoutside the villages. We also found significant relationships between speciesrichness and soil type. Silt proved to be the most species-rich topsoil(10–20 cm) in addition to thin soils top of on green- orlimestone bedrock. The variation in species richness due to local relief orform of thesite also showed significant relationships, where flat surfaces had the highestnumber of species. In contrast, no significant relationship was found betweenspecies richness and aspect. Our study suggests that present-day diversitypatterns are much influenced by management history, and that small habitat,e.g., road verges and midfield islets, are important for maintaining speciesrichness.This revised version was published online in May 2005 with corrections to the Cover Date.     

地被植物在南京仙林大学城景观规划中的应用

阐述园林地被植物的概念、生态习性,调查研究南京仙林大学城绿地中常见的多年生草本地被植物,同时对地被植物在景观规划中的配置应用及存在的问题进行探讨。     

The Impact of Misclassification in Land Use Maps in the Prediction of Landscape Dynamics

Land use maps are widely used in modeling land use change, urban sprawl, and for other landscape related studies. A misclassification confusion matrix for land use maps is usually provided as a measure of their quality and uncertainty. However, this very important information is rarely considered in land use map based studies, especially in modeling landscape dynamics. Ignoring uncertainty of land use maps may cause models to provide unreliable predictions. This study is an attempt to investigate the impact of the accuracy of land use maps used as input for an urban sprawl model. In the study area, the regional confusion matrix has been localized using a topographical map. Based on the regional and local confusion matrices, several error levels have been defined. The results showed that a localized confusion matrix that reflected the characteristics of the study area had error rates that were much different than the regional confusion matrix. The predictions of the probability of urban sprawl based on the land use maps and defined error levels were quite different.     

Regional patterns of riparian characteristics in the interior Columbia River basin, Northwestern USA: applications for restoration planning

Recent declines in anadromous Pacific salmonids (Oncorhynchus spp.) have been attributed, in part, to degradation of freshwater habitat. Because riparian areas directly affect instream habitat, assessing riparian characteristics is essential for predicting salmon habitat quality and for prioritizing restoration projects. We quantified land use modification of anadromous fish-bearing streams in the interior Columbia River basin at multiple resolutions. We identified riparian areas in several land use and land cover classes using remotely sensed data. We then interpreted aerial photographs at random locations within each class to quantify riparian modifications at a local (stream reach) scale. Riparian areas in agricultural and urban areas were significantly narrower (~30 m, median) than those in forested or shrub/grass areas (~70 m). The largest proportion of modified riparian areas occurred in low-gradient streams with floodplains in semi-arid ecoregions. Riparian vegetation in these areas is unlikely to provide adequate in-stream functions, making these areas a natural starting point for restoration prioritization. We investigated how existing riparian restoration projects were spatially related to riparian land use and found that restoration effort varied among subwatersheds. Effective strategies for restoring high quality salmon habitat will be watershed-specific and must restore natural watershed processes. By using a hierarchical analysis to identify regional strategies, restoration or conservation activity can be focused in specific basins and thereby increase the likelihood that efforts will significantly improve habitat conditions for listed salmonids.     

长沙城市公园绿地植物群落基本类型及物种多样性研究

公园是城市园林绿地系统的主体,也是植物群落及其物种多样性最丰富的地方。研究公园植物多样性可为城市生物多样性保护提供依据。根据对长沙市3个公园绿地植物群落的调查,分析和总结了长沙城市公园绿地植物群落组成和基本类型,论述了公园绿地物种多样性特征。     

Models to distinguish effects of landscape patterns and human population pressures associated with species loss in Canadian national parks

It is widely accepted that large protected areas are required to effectively conserve historical species composition. However, recent analyses of mammal species loss in Canadian and African national parks contradict earlier conclusions that extent of local extinctions (i.e., extirpations) is strongly inversely related to park size, suggesting that park size alone is inadequate to predict reserve designs that may sustain biodiversity. To plan protected areas that will meet conservation goals, reserve-design models that incorporate other landscape-scale factors in addition to reserve area are needed; potential factors include the types and intensity of land use and habitat change, together with land cover types, in and around parks. Additionally, human population size around parks, and visitor density in parks may affect species loss. We quantified land use, land cover, and human population in and around 24 Canadian national parks to model effects of human disturbance and changes in natural habitats on known mammal extirpations.Multiple regression models were compared using the Akaike Information Criterion (AIC_c). The most parsimonious model (AIC_c weighting w _i = 0.5391) emphasized effective habitat area in and around parks and not visitor numbers nor human population size around parks. Our model suggests that parks with as little as 3140 km² of effective habitat area inside may be large enough to conserve historical mammal species composition if they are also surrounded by at least 18 000 km² of effective habitat within 50 km of park boundaries.     

Predicting land cover changes and their impact on the sediment influx in the Lake Balaton catchment

The land cover pattern in the Lake Balaton catchment (Hungary) has been changing since decollectivization in the 1990s. These land cover changes significantly impact the landscape connectivity, controlling the influx of sediments into the lake. A comparison of high resolution land cover maps from 1981, 2000 and 2005 showed a significant extensification of the agriculture with land cover conversions from arable land and vineyards to grassland and forest. For each land unit transition probabilities were assessed using logistic regression techniques to evaluate to which extent land cover changes are controlled by physical or socio-economic parameters. A stochastic land cover allocation algorithm was applied to generate future land cover patterns. The landscape connectivity for each of the simulated land cover patterns was assessed by means of a distributed routing algorithm. The simulations suggest that further land abandonment in the upslope parts of the catchment will cause a non-linear reduction of average soil erosion rates. The changes, however, have a relatively low impact on the sediment volume entering the lake because of the land unit’s poor connectivity with permanent river channels. The major contributors to the lakes sediment load are the vineyards near the lakeshore. They are likely to be maintained because of their touristic value. A significant reduction of the total sediment input in the lake can be expected only if soil conservation measures in the vineyards near the shorelines are undertaken.