Using ecological networks to answer questions in global biogeography and ecology

Ecological networks have classically been studied at site and landscape scales, yet recent efforts have been made to collate these data into global repositories. This offers an opportunity to integrate and upscale knowledge about ecological interactions from local to global scales to gain enhanced insights from the mechanistic information provided by these data. By drawing on existing research investigating patterns in ecological interactions at continental to global scales, we show how data on ecological networks, collected at appropriate scales, can be used to generate an improved understanding of many aspects of ecology and biogeography—for example, species distribution modelling, restoration ecology and conservation. We argue that by understanding the patterns in the structure and function of ecological networks across scales, it is possible to enhance our understanding of the natural world.     

生态梯度轴(EGA)用于林木生态遗传的研究——CA方法估算EGA(CA_1)和EGA(r~2)

应用典型相关的原理和技术,将多元地理坐标和生态因子降维成1元,研究提出2个生态梯度轴(EGA);EGA(CA_1)和EGA(r~2)。通过白榆20个种源的2个EGA估算,它们与6个环境因子平均相关系数为0.8551和0.8804,复相关系数0.9998和0.9985,很好地综合了诸环境因子在对群体7个性状分析结果,EGA能很好描述梯度变异,证明了白榆种群属于连续变异模式。     

Where to invest in road mitigation? A comparison of multiscale wildlife data to inform roadway prioritization

Roads and associated traffic have significant impacts on wildlife, from direct mortality caused by vehicle collisions to indirect effects when wildlife avoid roads, restricting access to important resources. Road mitigation measures such as constructing wildlife passages over or under the road with directional fencing have proven effective at reducing wildlife vehicle collisions while also enabling wildlife to safely cross the road. Highway mitigation projects are led by transportation agencies with a primary purpose of improving motorist safety. More recently, through the discipline of road ecology, considerations have included safe wildlife passage through transportation corridors. To prioritize road sections for mitigation, data sources include animal vehicle collision data collected by transportation agencies and connectivity models generated by wildlife professionals. We used a third data source, pronghorn observations collected by citizen scientists, and demonstrated its value to prioritize potential wildlife mitigation sites. Our results clearly demonstrate a misalignment of road mitigation sites using animal-vehicle collision data and those of rarer species of interest.     

Genome-wide RAD sequencing data suggest predominant role of vicariance in Sino-Japanese disjunction of the monotypic genus Conandron (Gesneriaceae)

Disjunct distribution is a key issue in biogeography and ecology, but it is often difficult to determine the relative roles of dispersal vs. vicariance in disjunctions. We studied the phylogeographic pattern of the monotypic Conandron ramondioides (Gesneriaceae), which shows Sino-Japanese disjunctions, with ddRAD sequencing based on a comprehensive sampling of 11 populations from mainland China, Taiwan Island, and Japan. We found a very high degree of genetic differentiation among these three regions, with very limited gene flow and a clear Isolation by Distance pattern. Mainland China and Japan clades diverged first from a widespread ancestral population in the middle Miocene, followed by a later divergence between mainland China and Taiwan Island clades in the early Pliocene. Three current groups have survived in various glacial refugia during the Last Glacial Maximum, and experienced contraction and/or bottlenecks since their divergence during Quaternary glacial cycles, with strong niche divergence between mainland China + Japan and Taiwan Island ranges. Thus, we verified a predominant role of vicariance in the current disjunction of the monotypic genus Conandron. The sharp phylogenetic separation, ecological niche divergence among these three groups, and the great number of private alleles in all populations sampled indicated a considerable time of independent evolution, and suggests the need for a taxonomic survey to detect potentially overlooked taxa.     

The importance of ecological research for ecosystem management: The case of browsing by swamp wallabies (Wallabia bicolor) in commercially harvested native forests

Summary Ecosystem management often proceeds within the context of sub‐optimal relationships between ecologists and ecosystem managers, and management outcomes could be improved with greater collaboration between members of these disciplines. This paper identifies an ecosystem management problem resulting from the interaction between timber harvesting and browsing wallabies, and this case study is used to exemplify how ecological data and expertise can contribute to the process of ecosystem management. It is argued that appropriate use of existing ecological data, establishment of strategic new research and the implementation of management actions as experimental hypothesis tests can facilitate achievement of management objectives, but greater collaboration between ecologists and managers is required before this can occur. Reasons for sub‐optimal relationships are outlined, and the potential for structural change within large State‐run ecosystem management agencies to improve interactions between managers and ecologists is discussed.     

Measuring Success: Evaluating the Restoration of a Grassy Eucalypt Woodland on the Cumberland Plain, Sydney, Australia

Abstract We compared the floristic composition and structure of restoration areas of eucalypt woodland with untreated pasture (control) and remnant vegetation (reference) in western Sydney. The restored areas comprised over 1,000 ha of abandoned pasture, which had been treated to reduce weeds and planted with seedlings of 26 native plant species raised from seed obtained locally from remnant vegetation. Plantings were carried out 0–9 years ago. Floristic composition was measured in quadrats using frequency scores and cover abundance. As far as possible treatments and restoration ages were replicated across sites. Ordination and analyses of similarity failed to distinguish the composition of restored vegetation from that of untreated pasture, which were both significantly different from that of remnant vegetation. There was a weak compositional trend with age of restored vegetation, but this was not in the direction of increasing resemblance to remnant vegetation. There was some evidence for convergence in structural features of restored with remnant vegetation, but this was at least partly attributed to plant growth. Subject to constraints imposed by the sampling design, environmental factors, and spatial variation were discounted as explanations for the results. The results therefore suggest either failure of restoration treatments or a restoration trajectory that is too slow to detect within 10 years of establishment. Our conclusions agree with those of similar studies in other ecosystems and support: (1) the need to monitor restoration projects against ecological criteria with rigorous sampling designs and analytical methods, (2) further development of restoration methods, and (3) regulatory approaches that seek to prevent damage to ecosystems rather than those predicated on replacing losses with reconstructed ecosystems.     

The ecosystem approach to environmental assessment: moving from theory to practice

The ecosystem approach to environmental management is viewed by many as being fundamental to the development of appropriate management strategies. While this approach represents a major advance in the way researchers view environmental assessment, the approach in itself does not provide practical information as to what questions to ask and what tools to use in assessing and managing ecosystems. Similarly, the concept of ecosystem health, as it is usually defined, has little practical value for ecosystem managers. We suggest the next stage in environmental assessment will be the development of specific frameworks designed to assess individual ecosystems. Of primary importance is the need to consider the basic structure and function of the ecosystem itself. Such consideration, together with explicit identification of anthropogenic stresses particular to the system, serves to identify those components most at risk and those issues most deserving of attention. Researchers should explore critical linkages between environmental stressors and their observable, measurable and predictable effects on ecological parameters and use this understanding to develop a management strategy that incorporates appropriate ecological indicators. The importance of these considerations will be illustrated using examples from the Northern River Basins Study.     

A qualitative procedure for the assessment of the habitat integrity status of the Luvuvhu River (Limpopo system,South Africa)

The riparian zone and instream habitat integrity of the Luvuvhu River were assessed based on a qualitative rating of the impacts of major disturbance factors such as water abstraction, flow regulation, bed and channel modification, etc. A system was devised to assess the impact of these factors on the relative frequency and variability of habitats on a spatial and temporal scale gauged against habitat characteristics that could have been expected to occur under conditions not anthropogenically influenced. It was found that deterioration of habitat integrity can be ascribed primarily to water abstraction. This has resulted in the cessation of surface flow in a naturally perennial river during the dry season and during droughts with consequent tree deaths and a loss of fast flowing instream habitat types in the main stem of the river. The relatively small high rainfall area in the catchment, the highly variable rainfall pattern and the occurrence of sporadic severe droughts exacerbate the impact of water abstraction on the instream and riparian habitats with expected detrimental consequences for the associated biota. The effect of water abstraction is particularly severe in the lower part of the river which flows through the Kruger National Park as no perennial tributaries join the Luvuvhu River in this section. Other factors which affect the habitat integrity of the river are the removal of indigenous riparian vegetation in some river sections, encroachment by exotic vegetation, bank erosion and stream bed modification.     

Ecological implications of climate change will include surprises

In addition to assessing the impacts of CO₂ doubling on environment and society, more consideration is needed to estimate extreme events or surprises. This is particularly important at the intersection of disciplines like climate and ecology because the potential for large discontinuities is high given all the possible climate/biota interactions. The vast disparities in scales encountered by those working in traditional ecology (typically 20 m) and climatology (typically 200 km) make diagnoses of such interactions difficult, but these can be addressed by an emerging research paradigm we call strategic cyclical scaling (SCS). The need to anticipate outlier events and assign them subjective probabilities suggests emphasis on interdisciplinary research associations. The desire to reduce societal vulnerability to such events suggests the need to build adaptive management and diverse economic activities into social organizations. The effectiveness of adaptation responses to anticipated climatic changes is complicated when consideration of transient changes, regional disturbances, large unforseeable natural fluctuations and surprises are considered. Slowing down the rate of disturbances and decreasing vulnerability are advocated as the most prudent responses to the prospect of human-induced climatic changes.     

贺兰山不同生境旱生灌木的解剖学研究

贺兰山荒漠地带三种不同基质生境的２０种旱生灌木的营养器官的比较解剖学研究表明：其共同特点是叶片的表面积／体积的比值小,叶表具厚的角质层、表皮毛,气孔下陷、并具孔下室,叶向中栅栏组织发达;轴器官中木栓层细胞层数多,皮层较厚,机械组织发达,木薄壁组织及髓部细胞的细胞壁术化加厚,根内都具周皮、木质部的导管分子大小不一、频率较高。此外,根、茎、叶中普遍存在粘液细胞和草酸钙结晶,部分植物的根和茎内有异常维管组织。这些结构特征都与早生环境相关,而不同基质生境中生长的植物尚存在一定差异。