Towards an ecological understanding of biological nitrogen fixation

Biogeochemistry - N limitation to primary production and other ecosystem processes is widespread. To understand the causes and distribution of N limitation, we must understand the controls of...     

A study of Nigerian pupils' understanding of selected biological concepts

120 Nigerian Secondary school biology pupils, mostly aged 16–18, were interviewed individually to assess their level of understanding of a range of biological concepts. The concepts were related to growth, reproduction, and transport mechanisms within living organisms. The responses of each pupil were scored and examined to determine whether they revealed concrete or formal operational thinking. Given 21 opportunities to do so, almost 50 per cent of pupils either failed to exhibit formal thinking at all, or revealed it on only one occasion. Fewer than 5 per cent exhibited formal thinking on ten or more occasions. There was no significant difference in the performance of boys as compared with girls, nor between pupils whose parents were from different socio-economic groups. Pupils from urban schools performed significantly better than those from rural schools. Pupils' common misconceptions were identified. The importance of ascertaining pupils' misconceptions and their levels of understanding of biological concepts is discussed from the viewpoint of the classroom teacher.     

Geometrization of biological ideas: probablistic model of evolution

The paper deals with mathematical explication of such fundamental notions of theoretical biology as space of morphological properties, proper time, diversity of forms and phenomena, spontaneous changes. The author developed a nationally geometrical picture of the animate world. A probabilistic approach is used to describe the process of evolution, whose mechanism is given by the Bayesian syllogism. It is shown how the Bayesian approach can formally describe evolutionary changes of the whole pattern of properties. The author discusses some ideas dealing with the possibility of constructing a general field theory, embracing both such phenomena that are beyond the framework of physical science.     

Advancing our understanding of ecological stability

The concept of ecological stability occupies a prominent place in both fundamental and applied ecological research. We review decades of work on the topic and examine how our understanding has progressed. We show that our understanding of stability has remained fragmented and is limited largely to simple or simplified systems. There has been a profusion of metrics proposed to quantify stability, of which only a handful are used commonly. Furthermore, studies typically quantify one to two metrics of stability at a time and in response to a single perturbation, with some of the main environmental pressures of today being the least studied. We argue that we need to build on the existing consensus and strong theoretical foundation of the stability concept to better understand its multidimensionality and the interdependencies between metrics, levels of organisation and types of perturbations. Only by doing so can we make progress in the quantification of stability in theory and in practice, and eventually build a more comprehensive understanding of how ecosystems will respond to ongoing environmental change.     

The calculation of productivity factor for ecological footprints in China: A methodological note

The ecological footprint (EF), a physical indicator to measure the extent of humanity's use of natural resources, has gained much attention since it was first used by Wackernagel and Rees in 1996. In order to account for differences between countries in productivity of a given land type (i.e., arable land, pasture, forest and water/fishery), productivity factor was introduced to relate the regional primary bio-productivities of the 4 types of land to the integrated average primary bio-productivity of the corresponding land types. Hence, the productivity factor is an important parameter in the EF model and it directly affects the reliability of all results. Thus, this article calculates productivity factor on the national and provincial level in China based on Net Primary Production (NPP) from MODIS 1 km data in 2008. Firstly, based on the Light Utility Efficiency and CASA model, the NPP of different biologically productive lands of China and of different provinces was calculated. Secondly, China's productivity factor for a given land type was calculated as the ratio of national average NPP of that land type and world-average NPP of that land type. Finally, productivity factors of each province in China for a given land type was calculated. The NPP of each ecosystem type varies along with the productivity factor in different provinces. However, the ranking of the productivity factors remain the same, with that of arable land being the largest, and the water/fishery being the smallest.     

栓皮栎种群的生物学生态学特性和地理分布研究

对栓皮栎种群的地理分布和生物学,生态学特性进行了研究。结果表明：（1）栓皮栎幼苗期地上部分生长缓慢,而主要发育根系;（2）栓皮栎的有性生殖和无性生殖都受到人为干扰的强烈影响;无性繁殖在林分更新中占有重要的地位,而有性繁殖则是维持和丰富种群遗传多样性的基因;（3）栓皮栎喜光,但对温度,降雨和土壤要求并不严格;（4）通过对优势种群重要值进行聚类分析。可以将陕西栓皮栎种群所在群落划分为6个类型;（5）栓皮栎具有很强的适应性,是我国分布最广的树种之一。垂直分布幅度范围较大,分布的海拔上限自北向南,由东向西不断升高。     

Poplar in wetland agroforestry: a case study of ecological benefits,site productivity,and economics

Poplars are the major tree component of traditional agroforestry systems throughout the south temperate central area of China that includes all or portions of Jiangsu, Anhui, Zhejiang, Hubei, Henan, Shandong, and Shanxi provinces, an area of ~600,000 km². The lack of experidmental data on the effect of various interplanting systems on crop production represents a serious gap in our knowledge, and consequently, a stable, optimized poplar-crop interplanting pattern is difficult to achieve. In order to develop a poplar-crop interplanting pattern that is economically viable, environmentally sound, technically workable, and socially compatible in floodplain areas, new poplar-crop interplanting patterns were designed using the principle of edge effects. Six patterns were designed and established in 1992 with different narrow – wide spacings, i.e., I: (3 × 3) × 20 m, II: (3 × 3) × 30 m, III: (3 × 3) × 40 m, IV: (4 × 4) . 20 m, V: (4 × 4) × 30 m, and VI: (4 × 4) × 40 m. A randomized block arrangement was used with two replications for each pattern. Based on 7 years of investigation, this paper examines the effects of these patterns on temporal and spatial variations in microclimate at various phenological phases of winter wheat, variations in wheat yield and quality, wood production, biomass productivity and light use efficiency, and economic assessment. The feasibility and viability of these new patterns is also discussed. These preliminary results provide some basic principles for developing optimized poplar-crop interplanting patterns in the wetland plain areas of China.     

“再野化”:山水林田湖草生态保护修复的新思路

作为一种新兴的生态保护修复方法,“再野化”（rewilding）是指特定区域中荒野程度的提升过程,尤其强调提升生态系统韧性和维持生物多样性。再野化实践的核心要素包括保护核心荒野地、增加荒野地的连通性、保护和重引入关键种（包括大型食肉动物）、适度允许自然干扰的发生、降低人类干扰和管理程度、拆除部分人工基础设施等。评述了北美洲和欧洲的再野化实践。通过比较研究,提出基于再野化的我国山水林田湖草生态保护修复的新思路,包括战略层面的5项转变和行动层面的5项建议。5项战略转变,包括从还原论思维转向整体思维、从工程性修复转向保护优先和自然恢复为主、从项目尺度转向景观尺度、从短期试点转向长期实践、从政府主导转向多方参与;5项行动建议,包括开展荒野和再野化基础调查、保护仅存的高价值荒野地、探索“城-乡-野”系统性再野化途径、以荒野保护区和再野化区域为核心建立大尺度景观保护网络、开展基于再野化的生态体验和自然教育。     

The priority of prediction in ecological understanding

The objective of science is to understand the natural world; we argue that prediction is the only way to demonstrate scientific understanding, implying that prediction should be a fundamental aspect of all scientific disciplines. Reproducibility is an essential requirement of good science and arises from the ability to develop models that make accurate predictions on new data. Ecology, however, with a few exceptions, has abandoned prediction as a central focus and faces its own crisis of reproducibility. Models are where ecological understanding is stored and they are the source of all predictions – no prediction is possible without a model of the world. Models can be improved in three ways: model variables, functional relationships among dependent and independent variables, and in parameter estimates. Ecologists rarely test to assess whether new models have made advances by identifying new and important variables, elucidating functional relationships, or improving parameter estimates. Without these tests it is difficult to know if we understand more today than we did yesterday. A new commitment to prediction in ecology would lead to, among other things, more mature (i.e. quantitative) hypotheses, prioritization of modeling techniques that are more appropriate for prediction (e.g. using continuous independent variables rather than categorical) and, ultimately, advancement towards a more general understanding of the natural world. Synthesis Ecology, with a few exceptions, has abandoned prediction and therefore the ability to demonstrate understanding. Here we address how this has inhibited progress in ecology and explore how a renewed focus on prediction would benefit ecologists. The lack of emphasis on prediction has resulted in a discipline that tests qualitative, imprecise hypotheses with little concern for whether the results are generalizable beyond where and when the data were collected. A renewed commitment to prediction would allow ecologists to address critical questions about the generalizability of our results and the progress we are making towards understanding the natural world.     

Endopolyploidy: Towards an understanding of its biological significance

There is a certain measure of perplexity concerning the significance of endopolyploidy. It seems that this results from a narrow frame of reference from which investigators view the phenomenon; that is, a predilection for emphasizing the specialized functional aspect of endopolyploidy as it operates in species at the present time overrides any consideration of the rôle that this state may play in the life of a species in its encounter with the forces of natural selection either in the past or in the future.There does not seem to be any obvious relationship between the degree of endopolyploidy that a species can exhibit and either its basic DNA content or the structure of its nucleus. The significance of endopolyploidy may reside not so much in any specialized function that the condition can support, but rather in the properties that are consequent upon the endopolyploid condition itself and which are distinct from those that apply to diploid cells. Some of the properties of the endopolyploid state, and examples of their manifestation in plants and animals, are discussed. The conclusion is that these properties have a potential that opens possibilities for new paths of development and serves as a factor upon which natural selection can operate.     

Factors limiting our understanding of ecological scale

Multi-scale studies ostensibly allow us to form generalizations regarding the importance of scale in understanding ecosystem function, and in the application of the same ecological principles across a series of spatial domains. Achieving such generalizations, however, requires consistency among multi-scale studies not only in across-scale sample design, but also in basic rationales used in the choice of observational scale, including both grain and extent. To examine the current state of this science, here we review 79 multi-scale wildlife-habitat studies published since 1993. We summarize rationales used in scale choice and also review key differences in scale-specific experimental design among studies. We found on average that 70% of the observational scales employed in wildlife-habitat research were chosen arbitrarily with no biological connection to the system of study, and with no consideration regarding domains of scale for either dependent or independent variables. Further, we found it common to change either both grain and extent, or the entire suite of independent variables across scales, making cross-scale extrapolations and generalizations impossible. We discuss these sampling limitations by clarifying the differences between multi-scale versus multi-design studies, including the distinction between spatial versus scalar observations, and how these may differ from the commonly cited “orders of resource selection”. We conclude by reviewing both existing and suggested alternatives to reduce the arbitrary nature of observational-scale choice prevalent in today's literature.     

The vegetation adventivisation through perspective of modern ecological ideas

Results of study of vegetation adventivisation (increase in proportion of invasive species) correspond to the theory of present ecology that denies general universal laws. Diverse features of invasive species play different role under various ecological conditions and at various time and space scale. The invasibility of communities under various conditions is determined by combination of different biotic and abiotic factors though it is obvious that most of invasive species are characterized with the high seed production, well developed vegetative propagation, windblown pollination, high plasticity and effective use of resources, low consumption by herbivores. The definition of an "ideal invasive species" or an "ideal invasible community" is impossible. The regularities of vegetation adventivisation can be observed clearly only at very large scale.     

A truly ecological epigenetics study

Until a few years ago, epigenetics was a field of research that had nothing to do with ecology and that virtually no ecologist had ever heard of. This is now changing, as more and more ecologists learn about epigenetic processes and their potential ecological and evolutionary relevance, and a new research field of ecological epigenetics is beginning to take shape. One question that is particularly intriguing ecologists is to what extent epigenetic variation is an additional, and hitherto overlooked, source of natural variation in ecologically important traits. In this issue of Molecular Ecology, Herrera & Bazaga (2011) provide one of the first attempts to truly address this question in an ecological setting. They study variation of DNA methylation in a wild population of the rare, long-lived violet Viola cazorlensis, and they use these data to explore interrelations between environmental, genetic and epigenetic variation, and in particular the extent to which these factors are related to long-term differences in herbivore damage among plants. They find substantial epigenetic variation among plant individuals. Interestingly, this epigenetic variation is significantly correlated with long-term differences in herbivory, but only weakly with herbivory-related DNA sequence variation, which suggests that besides habitat, substrate and genetic variation, epigenetic variation may be an additional, and at least partly independent, factor influencing plant–herbivore interactions in the field. Although the study by Herrera & Bazaga (2011) raises at least as many new questions as it answers, it is a pioneering example of how epigenetics can be incorporated into ecological field studies, and it illustrates the value and potential novel insights to be gained from such efforts.     

Sound perception in plants: from ecological significance to molecular understanding

In addition to positive effects on plant growth and resilience, sound alerts plants of potential danger and aids in defense. Sound guides plants towards essential resources, like water, through phonotropic root growth. Sound also facilitates mutualistic interactions such as buzz pollination. Molecularly, sound induces Ca²⁺ signatures, K⁺ fluxes, and an increase in reactive oxygen species (ROS) levels in a mechanosensitive ion channel-dependent fashion. We review the two major open questions in the field of plant acoustics: (i) what is the ecological relevance of sound in plant life, and (ii) how is sound sensed and transduced to evoke a morphophysiological response? We highlight the clear need to combine the ecological and molecular perspectives for a more holistic approach to better understand plant behavior.     

Multi-scale trajectory analysis: powerful conceptual tool for understanding ecological change

The model at the basis of trajectory analysis is conceptually simple. When applied to time series vegetation data, the projectile becomes a surrogate for vegetation state, the trajectory for the evolving vegetation process, and the properties of the trajectory for the true process characteristics. Notwithstanding its simplicity, the model is well-defined under natural circumstances and easily adapted to serial vegetation data, irrespective of source. As a major advantage, compared to other models that isolate the elementary processes and probe vegetation dynamics for informative regularities on the elementary level, the trajectory model allows us to probe for regularities on the level of the highest process integrity. Theories and a data analytical methodology developed around the trajectory model are outlined, including many numerical examples. A rich list of key references and volumes of supplementary information supplied in the Web Only Appendices rounds out the presentation.     

Multi-scale trajectory analysis:powerful conceptual tool for understanding ecological change

The model at the basis of trajectory analysis is conceptually simple.When applied to time series vegetation data,the projectile becomes a surrogate for vegetation state,the trajectory for the evolving vegetation process,and the properties of the trajectory for the true process characteristics.Notwithstanding its simplicity,the model is well-defined under natural circumstances and easily adapted to serial vegetation data,irrespective of source.As a major advantage,compared to other models that isolate the elementary processes and probe vegetation dynamics for informative regularities on the elementary level,the trajectory model allows us to probe for regularities on the level of the highest process integrity.Theories and a data analytical methodology developed around the trajectory model are outlined,including many numerical examples.A rich list of key references and volumes of supplementary information supplied in the Web Only Appendices rounds out the presentation.     

Botswana1 children's understanding of biological inheritance

This paper reports the findings of an investigation which probed Batswana students' understanding of inheritance. A sample of students (aged 12 to 16+) responded to a pencil and paper questionnaire, which presented them with a variety of situations which they were asked to explain. Half of the sample were presented with English questions, and the other half with questions in Setswana (the vernacular language of the students). In both cases, they were asked to respond in the same language as the questions. Analysis of the responses revealed a variety of ‘alternative frameworks’, including a widespread belief in the inheritance of acquired characteristics. These are reported and discussed and their implications for teaching are explored. The language of the questions and responses and the gender of the students appeared to have little effect on the nature of the ideas revealed.