Genetic structure of expanding wolf (Canis lupus) populations in Italy and Croatia,and the early steps of the recolonization of the Eastern Alps

After centuries of range contraction and demographic declines wolves are now expanding in Europe, colonizing regions from where they have been absent for centuries. Wolf colonizing the western Alps originate by the expansion of the Italian population. Vagrant wolves of Italian and Dinaric-Balkan origins have been recently observed in the Eastern Alps. In this study we compared the genetic structure of wolf populations in Italy and Croatia, aiming to identify the sources of the ongoing recolonization of the Eastern Alps. DNA samples, extracted from 282 Italian and 152 Croatian wolves, were genotyped at 12 autosomal microsatellites (STR), four Y-linked STR and at the hypervariable part of the mitochondrial DNA control-region (mtDNA CR1). Wolves in Croatia and Italy underwent recent demographic bottlenecks, but they differ in genetic diversity and population structure. Wolves in Croatia were more variable at STR loci (N_A = 7.4, H_O = 0.66, H_E = 0.72; n = 152) than wolves in Italy (N_A = 5.3, H_O = 0.57, H_E = 0.58; n = 282). We found four mitochondrial DNA (mtDNA CR1) and 11 Y-STR haplotypes in Croatian wolves, but only one mtDNA CR1 and three Y-STR haplotypes in Italy. Wolves in Croatia were subdivided into three genetically distinct subpopulations (in Dalmatia, Gorski kotar and Lika regions), while Italian wolves were not sub-structured. Assignment testing shows that the eastern and central Alps are recolonized by wolves dispersing from both the Italian and Dinaric populations. The recolonization of the Alps will predictably continue in the future and the new population will be genetically admixed and very variable with greater opportunities for local adaptations and survival.     

Disentangling patch and landscape constraints of nested assemblages

The role of the matrix for the functionality of residual patches and therefore for species persistence has been recently recognised. However its influence on assemblage structure and composition is still unclear. We studied the effect of both patch and matrix attributes on community assemblage structure and composition in a fragmented landscape of central Italy. We used bird assemblages as a study model. Birds were sampled in 24 wood patches and distribution patterns were analysed considering both assemblage and guild-level responses. Patch composition and structure together with landscape patterns quantified with GIS were used as explanatory variables. The assemblages appeared to be strongly influenced by the landscape context, both in terms of composition and configuration. The functional connectivity of the patches, in terms of amount of neighbouring borders between woods and hedgerows, the shape of the woods in the matrix, together with the age of the patches, expressed as tree diameter, acted as the essential determinants, and even if the assemblages presented a significant nested structure, seven out of 40 species showed an idiosyncratic distribution. The study of the association between functional guilds and environmental parameters highlighted the influence of ecological constraints on the occurrence of unexpected presences and absences, suggesting the ability of some species to perceive and exploit matrix habitats. The matrix holds the capability to at least mitigate the effects of isolation and habitat loss, and the semi-natural elements of the mosaic may represent a biodiversity reservoir in an otherwise deprived landscape.     

Different factors affect the local distribution,persistence and spread of alien tree species in floodplain forests

Floodplain forests are characterized by high and increasing levels of invasions by plant species, but the factors that drive their spread are insufficiently understood. Using data from 708 plots surveyed twice (1998, 2008) supplemented with further data (management, stand age, distance to dispersal corridors, type of ecosystems invaded) we analyzed the factors which shape the local distribution, growth, persistence and spread of three invasive alien tree species (Acer negundo, Ailanthus altissima, Robinia pseudoacacia) in the National Park Donau-Auen in Austria. Using Generalized Linear Models (GLMs), we found that the distribution of the study species per plot is contingent on stand age (R. pseudoacacia), type of floodplain forest (A. negundo, A. altissima) and distance to the next water body (A. negundo). For all study species, colonization of new plots between both surveys is driven by short distance spread from already established invasion foci. Moreover, recipient habitats (softwood vs. hardwood floodplain forests) modify invasion success in species-specific ways. The probability of occurrence and colonization of plots located in softwood floodplain forests is higher for A. negundo, whereas A. altissima more frequently colonizes hardwood floodplain forests. Persistence of R. pseudoacacia decreases with stand age, whereas its growth rate is significantly higher in plots located in zones where management is allowed than in those which are not managed. Persistence and growth of the other two study species were not related to any explanatory variables analyzed. The on-going spread of the study species in the National Park Donau-Auen suggests that their local distribution is in disequilibrium, i.e. not all suitable habitat patches have yet been colonized. This implies that increased management efforts are necessary to reverse the spread of alien tree species in the study area and to maintain the high conservation value of this iconic area which protects one of the largest floodplain forests in Europe.     

Landscape structure versus the effectiveness of nature conservation: Roztocze region case study (Poland)

The objective of the study was to examine the extent to which landscape metrics could be used as an indicator of efficient management of protection areas. The selected sampling areas were natural–landscape units distinguished within the Roztocze Region located in the central-east Poland. Among 446 units, those representing three typological groups determined by three factors were selected. The factors included (1) the area of the unit; (2) the dominant or characteristic type of ecosystem; and (3) the form of protection. Subsequently, thirteen landscape metrics were calculated with the application of the Fragstats software. The analysis revealed high correlation between the form of nature protection and the majority of the calculated indexes. National park units show the highest landscape diversity and stability of various types of ecosystems. This suggests high conservation efficiency. Landscape park units are distinguished by fragmented patchy composition, and spatial structure even less stable than that of the non-protected areas. The study results show that landscape metrics could be used as an indicator of efficient management of different forms of nature protection. They provide an insight into the structure and functioning of the environment at various levels of its organisation. We particularly found diversity metrics to be useful for indicating whether nature conservation goals are archived, and the size and density metric for measuring human interference in the landscape. The selection and interpretation of indexes should be determined by the specific character of a given area.     

The design and function of birds' nests

All birds construct nests in which to lay eggs and/or raise offspring. Traditionally, it was thought that natural selection and the requirement to minimize the risk of predation determined the design of completed nests. However, it is becoming increasingly apparent that sexual selection also influences nest design. This is an important development as while species such as bowerbirds build structures that are extended phenotypic signals whose sole purpose is to attract a mate, nests contain eggs and/or offspring, thereby suggesting a direct trade‐off between the conflicting requirements of natural and sexual selection. Nest design also varies adaptively in order to both minimize the detrimental effects of parasites and to create a suitable microclimate for parents and developing offspring in relation to predictable variation in environmental conditions. Our understanding of the design and function of birds' nests has increased considerably in recent years, and the evidence suggests that nests have four nonmutually exclusive functions. Consequently, we conclude that the design of birds' nests is far more sophisticated than previously realized and that nests are multifunctional structures that have important fitness consequences for the builder/s.     

基于分割的多尺度城市绿地景观

利用多分辨率分割生成3种尺度的城市绿地景观.以50像元和300像元的目标分割值生成小尺度和大尺度的景观影像目标层,利用最近邻法分类两个目标层.对小尺度景观分类后的结果进行分割生成中间尺度的景观影像目标层并进行分类.从3个景观尺度的分类目标层中矢量化提取出绿地信息并计算6个景观指数：多样性、优势度、均匀度和分维数、破碎度和内缘比.多样性、优势度、均匀度和分维数的最大值分别为2.2、0.681、0.948和0.326,最小分别为1.641、0.122、0.707和0.113.表明多样性、均匀度和破碎度随着景观尺度的增大而减小,优势度随着景观尺度的增大而增大.基于分割产生多尺度景观的方法可以满足城市绿地景观研究的需求.     

煤矿井田区地表沉陷对植被景观的影响——以山西省晋城市东大煤矿为例

借助地表沉陷预测模型,预测了地表沉陷状况,依据地表沉陷对景观的破坏程度划分出重度影响区和轻度影响区;在遥感及地理信息系统技术的支持下,把植被景观现状与地表沉陷影响区叠加,通过沉陷前后景观格局的变化分析,对山西省晋城市东大煤矿的生态影响进行了探索性评价研究。结果表明:1) 重度影响区地表会出现盆型、马鞍型和波浪型等塌陷或裂缝,土壤侵蚀的作用将导致土壤养分空间格局发生明显变化。塌陷或裂缝周围生境恶化,成为养分流失源,植被恢复困难;养分汇处土壤水、肥条件优越,植被演替迅速,适当的人为干扰可以加快区域生态环境的恢复步伐。2) 地表沉陷后,植被景观破碎及隔离程度严重,原有的稳定态景观格局被打破,随着地形、土壤的空间变化,植被开始新一轮发展演替。由于原先占绝对优势的退化植被类型白羊草(Bothriochloa ischemum)-百里香(Thymus mongolicus)型优势度下降,同时,大部分次优势景观的内部生态功能受影响不大,这对景观整体的生物多样性以及次优势景观类型的演替是有益的,但是,重度影响区对斑块的隔离呈直线性,这对物种迁移的障碍是明显的。因此,重视井田区的封育与引种工作,科学规划、合理布局,在此基础上,引导植被演替沿着白羊草-百里香型—白羊草-黄背草(Themeda japonica)型—灌木丛—阔叶林的方向发展是可行的。     

郑州黄河滩地生态重建研究

通过生态重建和景观重建,使郑州黄河滩地重新发挥生态系统功能与价值。以郑州黄河滩地为研究区,以实地调查数据、卫片资料等为依据,通过合理地定位重建目标、控制景观结构、划分景观分区和采用生态经济学方法进行成效评估,制定郑州黄河滩地生态重建方案。郑州黄河滩地蕴含着巨大的生态系统服务功能与价值潜力,生态重建后可以为城市公众提供更好的服务。主要表现为生态功能:生物多样性维持功能,调节气候和涵养水源功能,保持土壤和净化环境功能,生态防灾功能;经济生产功能和社会功能:科研教育功能,旅游和遗产价值。     

厦门滨海湿地景观格局变化研究

选取了厦门市1986年,1993年和2003年三个时期遥感影像解译数据作为基本信息源.在ArcGIS支持下,应用GIS技术获取滨海湿地基本数据,通过对景观格局指数的计算和分析,对过去17年间厦门滨海湿地的景观格局变化特征进行了研究.结果表明:湿地总面积呈下降趋势,由1986年的419.764km²下降至2003年的394.237km²,湿地斑块数量由1986年的810块增加至2003年的1092块.湿地景观破碎度不断增加,而研究区域湿地景观多样性指数和均匀度指数则下降.