Observer error in vegetation surveys: a review

Aims Vegetation sampling employing observers is prone to both inter-observer and intra-observer error. Three types of errors are common: (i) overlooking error (i.e. not observing species actually present), (ii) misidentification error (i.e. not correctly identifying species) and (iii) estimation error (i.e. not accurately estimating abundance). I conducted a literature review of 59 articles that provided quantitative estimates or statistical inferences regarding observer error in vegetation studies.Important findings Almost all studies (92%) that tested for a statistically significant effect of observer error found at least one significant comparison. In surveys of species composition, mean pseudoturnover (the percentage of species overlooked by one observer but not another) was 10–30%. Species misidentification rates were on the order of 5–10%. The mean coefficient of variation (CV) among observers in surveys of vegetation cover was often several hundred % for species with low cover, although CVs of 25–50% were more representative of species with mean covers of>50%. A variety of metrics and indices (including commonly used diversity indices) and multivariate data analysis techniques (including ordinations and classifications) were found to be sensitive to observer error. Sources of error commonly include both characteristics of the vegetation (e.g. small size of populations, rarity, morphology, phenology) and attributes of the observers (e.g. mental fatigue, personal biases, differences in experience, physical stress). The use of multiple observers, additional training including active feedback approaches, and continual evaluation and calibration among observers are recommended as strategies to reduce observer error in vegetation surveys.     

Diel variation in movement patterns and habitat use by the Iberian endemic Cabrera vole: Implications for conservation and monitoring

Understanding variations in animal movement and habitat selection behaviour over fine spatial and temporal scales remains a particularly challenging goal in ecology and conservation. Here we document for the first time the diel variations in movement patterns and habitat use by wild-ranging Cabrera voles in fragmented Mediterranean farmland, based on radiotracking data (2006–2008) of 25 adult individuals occupying stable home-ranges in vegetation mosaics dominated by wet grasses and shrubs. Results indicated that the proportion of time animals spent moving, the distance moved, and the selection strength of main vegetation types were closely linked behavioural traits, which varied considerably across different periods of the 24-h cycle. In general, voles moved more frequently and over larger distances during daytime (between 06 h15–22 h00), which was when wet grasses were also used more intensively. These patterns were generally consistent across seasons, though during the dry season there was some tendency for a decrease in movement activity during the hottest hours of the day (between 10 h15–14 h00), with peaks around crepuscular hours (06 h15–10 h00 and 18 h15–22 h00). Overall, our study provides evidence that Cabrera voles may show notable shifts in habitat use and movement patterns on a finer scale than previously considered. This supports the idea that knowledge of the diel variations in species movement-habitat relationships should strongly contribute to improving local habitat management, as well as effective sampling and monitoring programs targeting the species.     

Assessing the assessors: Quantifying observer variation in vegetation and habitat assessment

Vegetation assessment protocols used in research, monitoring and statutory planning often rely on the consistent application of methods by multiple assessors. Consequently, a study was undertaken to evaluate the application of a vegetation condition assessment protocol by a range of assessors. The aim of the study was to quantify variation among assessors in their measurement of field‐based vegetation attributes using Queensland’s BioCondition protocol, and to determine the effect of variability on the final condition score. The study consisted of 77 assessors, ranging from nil to 25 years experience in vegetation assessment, who each undertook an assessment at one site following training. Six of the 20 attributes used to derive the final condition score were not assessed consistently, this being because of a small number of assessors who had misinterpreted the protocol and had inappropriately assessed some attributes. Despite inclusion of outliers, 82% of assessors were within 10 points of the median condition score for the site. Based on the results, the definition and measurement of problematic attributes have been either clarified or removed from the revised assessment procedure. The study demonstrated that with training prior to use, assessors were able to consistently assess condition at the study site.     

Geographical gradients in the biodiversity of Chinese freshwater molluscs: Implications for conservation

Aim

Large ‐ scale diversity patterns are generated by different but not mutually exclusive mechanisms. However, understanding of multiple facets of diversity and their determinants in the freshwater realm remains limited. Here, we characterized the geographical gradients, hotspots and spatial congruence of three facets of freshwater molluscan diversity and evaluated the relative importance of three different underlying mechanisms related to the energy, area/environmental heterogeneity and dispersal/historical hypotheses.

Location

China.

Methods

Species richness (SR), functional richness (FR) and taxonomic distinctness (TD, a proxy of phylogenetic diversity) were calculated for 212 drainage basins with a total of 313 molluscan species. Spatial congruence between the diversity facets was evaluated with Pearson correlation coefficient and overlap among hotspots. Multiple linear regression models and variation partitioning were used to assess the relative importance of different mechanisms.

Results

Hotspots of SR and FR were mainly concentrated in the Yangtze River and Huai River basins, while high TD values were patchily distributed across China. We found extremely low spatial congruence between TD and both SR and FR, while there was relatively high concordance between SR and FR. All diversity facets were best explained by the dispersal/historical hypothesis with strong unique effects, followed by the factors related to the energy hypothesis. The area/ environmental heterogeneity hypothesis was only weakly supported.

Main conclusions

We found a potentially strong influence of dispersal limitation and evolutionary history on the geographical diversity gradients of Chinese molluscs. This finding contrasts with the general finding that energy‐related factors are the strongest correlates of diversity patterns at large spatial scales. Moreover, our results do not support the idea that using any one diversity component as a surrogate of the others in developing conservation strategies. Instead, an integrative approach embracing multiple facets of diversity should be adopted in the conservation of freshwater biodiversity.

     

Reference situations for biodiversity in life cycle assessments: conceptual bridging between LCA and conservation biology

The International Journal of Life Cycle Assessment - In life cycle assessment (LCA) literature addressing land use impacts on biodiversity, several potential reference situations are proposed....     

Potential distribution of Ursus americanus in Mexico and its persistence: Implications for conservation

The black bear Ursus americanus is an endangered species in Mexico. Its historical distribution has decreased by approximately 80% although its current distribution is not known with precision; it is only reported to be present in the mountains of Northern Mexico. This study proposes two ensemble models: Mexicós black bear (a) potential distribution compared with Natural Protected Areas (NPAs); and, (b) persistence areas for 2024. The current distribution variables are coniferous forest, elevation and dry forest. Suitable habitat for black bear (354,047 km², 18.07% of the country) was found mainly in the north of the Sonoran biogeographical zone, along the Sierra Madre Occidental, the center and south of the Sierra Madre Oriental and some northern regions of the Altiplano Norte. Comparing these areas with NPAs documented that only 12.41% of potential distribution coincided with current suitable habitat. There are unprotected areas in Sierra Madre Occidental center and central and southern of Sierra Madre Oriental. The model for 2024 indicates a reduction of suitable habitat of 64.5%, mainly in the northern Sonoran zone and the center Sierra Madre Occidental. On the other hand, areas that will persist (125,673 km²) are located along the two main mountain ranges of Mexico. Identification of these sites will allow strengthening of long-term conservation strategies.     

Interobserver error in grassland vegetation surveys: sources and implications

人类观测误差是植被测量中不可避免的一个问题。我们量化了与高草草原植被长期监测相关的观测者间误差的四个组成部分：忽略误 差、误识别误差、谨慎误差和估计误差。由于观察者会产生误差,我们还评估了地块大小与伪周转率的关系,以及对比了物种组成和丰度的伪变化与四年间植被变化之间的关系。这项研究是在美国堪萨斯州的高草草原国家保护区进行的。监测点包括10个地块,每个地块由一系列的四个嵌套框架(0.01, 0.1, 1和10 m²)组成。在每个嵌套框架中记录了所有的草本物种,并且在10 m²的空间尺度下,视觉估计了7个覆盖类别内的叶面覆盖。总共调查了300个地块(30个地点),并随机选择28个地块重新进行测量以评估观测者的误差。所有的调查由四名观测者分两组完成。研究结果表明,在10 m²空间尺度上,由忽略误差引起的伪周转率平均为18.6%,而由误识别误差和谨慎误差引起的伪周转率平均值分别为1.4%和0.6%。尽管由重新定位引起的误差可能也起一定的作用,由忽略误差导致的伪周转率随样地面积的减小而增 加。物种组成在四年期间的变化(排除潜在的误识别误差和谨慎误差)为30.7%,其中包括由忽略误差和实际变化引起的伪周转率。18.6%的忽略误差表明四年期间的实际变化只有12.1%。对于估计误差,26.2%会记录为不同的覆盖等级。在四年的时间内,46.9%的记录显示了不同的覆盖等级,这表明两个时间段间覆盖率变化的56%是由于观测者误差造成的。     

Integrating invasive mammal eradications and biodiversity offsets for fisheries bycatch: conservation opportunities and challenges for seabirds and sea turtles

The removal of invasive mammals from islands is one of society’s most powerful tools for preventing extinctions and restoring ecosystems. Given the demonstrable high conservation impact and return on investment of eradications, new networks are needed to fully leverage invasive mammal eradications programs for biodiversity conservation at-large. There have been over 800 invasive mammal eradications from islands, and emerging innovations in technology and techniques suggest that island area will soon no longer be the limiting factor for removing invasive mammals from islands. Rather, securing the necessary social and economic capital will be one main challenge as practitioners target larger and more biologically complex islands. With a new alliance between conservation practitioners and the fisheries sector, biodiversity offsets may be a promising source of capital. A suite of incentives exists for fisheries, NGOs, and governments to embrace a framework that includes fishery bycatch offsets for seabirds and sea turtles. A bycatch management framework based on the hierarchy of “avoid, minimize, and offset” from the Convention on Biological Diversity would result in cost-effective conservation gains for many threatened seabirds and sea turtles affected by fisheries. Those involved with island conservation and fisheries management are presented with unprecedented opportunities and challenges to operationalize a scheme that will allow for the verifiable offset of fisheries impacts to seabirds and sea turtles, which would likely result in unparalleled marine conservation gains and novel cross-sector alliances.     

Climate change effects on behavioral and physiological ecology of predator–prey interactions: Implications for conservation biological control

Habitat management under the auspices of conservation biological control is a widely used approach to foster conditions that ensure a diversity of predator species can persist spatially and temporally within agricultural landscapes in order to control their prey (pest) species. However, an emerging new factor, global climate change, has the potential to disrupt existing conservation biological control programs. Climate change may alter abiotic conditions such as temperature, precipitation, humidity and wind that in turn could alter the life-cycle timing of predator and prey species and the behavioral nature and strength of their interactions. Anticipating how climate change will affect predator and prey communities represents an important research challenge. We present a conceptual framework—the habitat domain concept—that is useful for understanding contingencies in the nature of predator diversity effects on prey based on predator and prey spatial movement in their habitat. We illustrate how this framework can be used to forecast whether biological control by predators will become more effective or become disrupted due to changing climate. We discuss how changes in predator–prey interactions are contingent on the tolerances of predators and prey species to changing abiotic conditions as determined by the degree of local adaptation and phenotypic plasticity exhibited by species populations. We conclude by discussing research approaches that are needed to help adjust conservation biological control management to deal with a climate future.     

Rapid genetic identification of local provenance seed collection zones for ecological restoration and biodiversity conservation

The ecological restoration of native plant communities requires the collection of large amounts of seed. Use of non-local provenance seed can have detrimental consequences for the success of restoration if there is a home-site advantage, and for nature conservation through the erosion of natural patterns of population genetic structuring and/or genetic swamping (and extirpation) of locally significant genotypes. As part of an ongoing project to genetically delineate local provenance seed collection zones for species within a large urban bushland remnant of high conservation value, we assessed population genetic differentiation in two widespread coastal leguminous species, Acacia rostellifera and A. cochlearis (Fabaceae), commonly used in restoration programmes in SW Australia. Using amplified fragment length polymorphism (AFLP), we found very high levels of genetic differentiation among populations, with an analysis of molecular variance (AMOVA) showing more than 50% of the total genetic variance to be partitioned among populations (Φ_ST=0.58 and 0.51 for A. rostellifera and A. cochlearis, respectively), and marked non-overlap of almost all potential seed source populations from the local population in ordinations. Our results suggest extremely restricted natural dispersal among populations, possibly due to a combination of low seed set, seed dispersal by ants, clonality, a linear distribution of naturally fragmented populations and possibly low outcrossing rates. We suggest a narrow seed collection zone should be applied to these species for the conservation of genetic diversity and natural patterns of population genetic structure, and we highlight the value and importance of provenance evaluation to ecological restoration.     

Robust hierarchical state-space models reveal diel variation in travel rates of migrating leatherback turtles

1. Biological and statistical complexity are features common to most ecological data that hinder our ability to extract meaningful patterns using conventional tools. Recent work on implementing modern statistical methods for analysis of such ecological data has focused primarily on population dynamics but other types of data, such as animal movement pathways obtained from satellite telemetry, can also benefit from the application of modern statistical tools. 2. We develop a robust hierarchical state-space approach for analysis of multiple satellite telemetry pathways obtained via the Argos system. State-space models are time-series methods that allow unobserved states and biological parameters to be estimated from data observed with error. We show that the approach can reveal important patterns in complex, noisy data where conventional methods cannot. 3. Using the largest Atlantic satellite telemetry data set for critically endangered leatherback turtles, we show that the diel pattern in travel rates of these turtles changes over different phases of their migratory cycle. While foraging in northern waters the turtles show similar travel rates during day and night, but on their southward migration to tropical waters travel rates are markedly faster during the day. These patterns are generally consistent with diving data, and may be related to changes in foraging behaviour. Interestingly, individuals that migrate southward to breed generally show higher daytime travel rates than individuals that migrate southward in a non-breeding year. 4. Our approach is extremely flexible and can be applied to many ecological analyses that use complex, sequential data.     

Creative Commons licenses and the non-commercial condition: Implications for the re-use of biodiversity information

The Creative Commons (CC) licenses are a suite of copyright-based licenses defining terms for the distribution and re-use of creative works. CC provides licenses for different use cases and includes open content licenses such as the Attribution license (CC BY, used by many Open Access scientific publishers) and the Attribution Share Alike license (CC BY-SA, used by Wikipedia, for example). However, the license suite also contains non-free and non-open licenses like those containing a "non-commercial" (NC) condition. Although many people identify "non-commercial" with "non-profit", detailed analysis reveals that significant differences exist and that the license may impose some unexpected re-use limitations on works thus licensed. After providing background information on the concepts of Creative Commons licenses in general, this contribution focuses on the NC condition, its advantages, disadvantages and appropriate scope. Specifically, it contributes material towards a risk analysis for potential re-users of NC-licensed works.     

Biodiversity in montane Britain: habitat variation,vegetation diversity and some objectives for conservation

The montane (low- to mid-alpine) zone in Great Britain (GB) lies above the potential tree-line (700–800 m, but descending to 200 m in the north). It is composed of moss and lichen heaths, snowbeds, blanket bog and dwarf-shrub (Ericaceae) health-covered solifluction/gelifluction terraces (38 communities/sub-communities). Approximately 3.0% of the land surface is covered by this- the most extensive predominantly near-natural terrestrial habitat in GB. Internationally distinctive features include oceanic and southern biotic outliers of arctic-alpine fellfield and mountain tundra, and plant communities that are either globally rare/localised or especially well represented in GB. The absence of extensive sub-alpineBetula spp. andSalix spp. scrub is striking.The main sources of habitat diversity are climate, regional variation in topography and geology, and regional modifications due to land-use impact. Over 50 examples are given. Five important gradients in Scottish Highland vegetation are described. Only some 15% of the sampled montane vegetation is anthropogenic; the rest is semi- or near-natural. The vegetation is divided into 5 functional groups: chionophobous (avoids snow), chionophilous (prefers snow), species-rich, mires (including springs and flushes), and anthropogenic. Chionophobous and then chionophilous communities contribute most to montane vegetation diversity (calculated here as the ShannonH diversity index).H diversity increases asymptotically with montane site area but linearly with the number of communities present. A more varied topography, geology and topo-climate gives the highestH diversity.Two examples of montane biodiversity reductions south of the Highlands are the loss of prostrateCalluna vulgaris heaths and modification ofRacomitrium lanuginosum healths. Five objectives for nature conservation are proposed, covering restoration of montaneR. lanuginosum healths, prostrate dwarf-shrub dominated heaths, sub-alpine scrub and upper treelines, and the extension of the breeding ranges of both ptarmigan (Lagopus mutus) and dotterel (Charadrius morinellus) south of the Scottish Highlands. International support for monitoring is sought.     

Seasonal and interannual variation in vegetation composition: Implications for survey design and data interpretation

Understanding how vegetation composition varies with season and interannual climate variability is important for any ecological research that uses vegetation data derived from surveys for the basis of inference. Misunderstanding this variation can influence land management and planning decisions, leading to poor implementation of biodiversity offsetting mechanisms, for example. We monitored plots (400 m²) grazed by livestock paired with adjacent ungrazed plots in derived native pastures four times a year over 2.5 years on the North‐West Slopes of New South Wales. Species density in plots varied greatly with season and interannual rainfall. Highest species density was recorded in spring, though species density in summer was not significantly lower, nor was a spring–summer peak in species density evident in the 2009 drought. Surveys in spring 2008 had the highest species density, and recorded only 60–72% of the total species recorded at each site over 2.5 years. Variation in the proportion of total site diversity represented in combinations of two or three surveys was large, though the best combinations comprised surveys from spring and summer in years of above‐average rainfall, either from the same spring‐summer, or from different years. Compositional differences among sites were much greater than within sites, showing that differences among sites related to broad environmental gradients were not overwhelmed by seasonal and interannual variability in site composition. When grazing was excluded, there was no evidence of competitive exclusion by the dominant grasses, and no directional shift in composition. The implications of these findings for ecological research depend on the question being addressed: if capturing a large proportion of site diversity is important, then surveys must be carefully timed, or repeat surveys must be conducted. Single surveys did not effectively capture site diversity for use in biodiversity offsetting, and the timing of repeat surveys was critical.     

Optimal allocation of Red List assessments to guide conservation of biodiversity in a rapidly changing world

The IUCN Red List is the most extensive source of conservation status assessments for species worldwide, but important gaps in coverage remain. Here, we demonstrate the use of a spatial prioritization approach to efficiently prioritize species assessments to achieve increased and up‐to‐date coverage efficiently. We focus on freshwater fishes, which constitute a significant portion of vertebrate diversity, although comprehensive assessments are available for only 46% of species. We used marxan to identify ecoregions for future assessments that maximize the coverage of species while accounting for anthropogenic stress. We identified a set of priority regions that would help assess one‐third (ca 4000 species) of all freshwater fishes in need of assessment by 2020. Such assessments could be achieved without increasing current investment levels. Our approach is suitable for any taxon and can help ensure that species threat assessments are sufficiently complete to guide global conservation efforts in a rapidly changing world.