Построение отказоустойчивых каналов связи на базе оборудования MikroTik

Материалы XIX Междунар. науч.-техн. конф. студентов, аспирантов и молодых ученых, Гомель, 25–26 апр. 2019 г

Winners and losers over 35 years of dragonfly and damselfly distributional change in Germany

Aim: Recent studies suggest insect declines in parts of Europe; however, the generality of these trends across different taxa and regions remains unclear. Standardized data are not available to assess large-scale, long-term changes for most insect groups but opportunistic citizen science data are widespread for some. Here, we took advantage of citizen science data to investigate distributional changes of Odonata. Location: Germany. Methods: We compiled over 1 million occurrence records from different regional databases. We used occupancy-detection models to account for imperfect detection and estimate annual distributions for each species during 1980–2016 within 5 × 5 km quadrants. We also compiled data on species attributes that were hypothesized to affect species’ sensitivity to different drivers and related them to the changes in species’ distributions. We further developed a novel approach to cluster groups of species with similar patterns of distributional change to represent multispecies indicators. Results: More species increased (45%) than decreased (29%) or remained stable (26%) in their distribution (i.e. number of occupied quadrants). Species showing increases were generally warm-adapted species and/or running water species, while species showing decreases were cold-adapted species using standing water habitats such as bogs. Time series clustering defined five main patterns of change—each associated with a specific combination of species attributes, and confirming the key roles of species’ temperature and habitat preferences. Overall, our analysis predicted that mean quadrant-level species richness has increased over most of the time period. Main conclusions: Trends in Odonata provide mixed news—improved water quality, coupled with positive impacts of climate change, could explain the positive trends of many species. At the same time, declining species point to conservation challenges associated with habitat loss and degradation. Our study demonstrates the great value of citizen science and the work of natural history societies for assessing large-scale distributional change

The conservation status and population decline of the African penguin deconstructed in space and time

Understanding changes in abundance is crucial for conservation, but population growth rates often vary over space and time. We use 40 years of count data (1979–2019) and Bayesian state-space models to assess the African penguin Spheniscus demersus population under IUCN Red List Criterion A. We deconstruct the overall decline in time and space to identify where urgent conservation action is needed. The global African penguin population met the threshold for Endangered with a high probability (97%), having declined by almost 65% since 1989. An historical low of ~17,700 pairs bred in 2019. Annual changes were faster in the South African population (−4.2%, highest posterior density interval, HPDI: −7.8 to −0.6%) than the Namibian one (−0.3%, HPDI: −3.3 to +2.6%), and since 1999 were almost −10% at South African colonies north of Cape Town. Over the 40-year period, the Eastern Cape colonies went from holding ~25% of the total penguin population to ~40% as numbers decreased more rapidly elsewhere. These changes coincided with an altered abundance and availability of the main prey of African penguins. Our results underline the dynamic nature of population declines in space as well as time and highlight which penguin colonies require urgent conservation attention

The power of monitoring: optimizing survey designs to detect occupancy changes in a rare amphibian population

Biodiversity conservation requires reliable species assessments and rigorously designed surveys. However, determining the survey effort required to reliably detect population change can be challenging for rare, cryptic and elusive species. We used a tropical bromeliad-dwelling frog as a model system to explore a cost-effective sampling design that optimizes the chances of detecting a population decline. Relatively few sampling visits were needed to estimate occupancy and detectability with good precision, and to detect a 30% change in occupancy with 80% power. Detectability was influenced by observer expertise, which therefore also had an effect on the sampling design – less experienced observers require more sampling visits to detect the species. Even when the sampling design provides precise parameter estimates, only moderate to large changes in occupancy will be detected with reliable power. Detecting a population change of 15% or less requires a large number of sites to be surveyed, which might be unachievable for range-restricted species occurring at relatively few sites. Unless there is high initial occupancy, rare and cryptic species will be particularly challenging when it comes to detecting small population changes. This may be a particular issue for long-term monitoring of amphibians which often display low detectability and wide natural fluctuations

Timing of autumn bird migration under climate change: advances in long-distance migrants, delays in short-distance migrants.

As a response to increasing spring temperature in temperate regions in recent years, populations of many plant and animal species, including migratory birds, have advanced the seasonal start of their reproduction or growth. However, the effects of climate changes on subsequent events of the annual cycle remain poorly understood. We investigated long-term changes in the timing of autumn migration in birds, a key event in the annual cycle limiting the reproductive period. Using data spanning a 42-year period, we analysed long-term changes in the passage of 65 species of migratory birds through Western Europe. The autumn passage of migrants wintering south of the Sahara has advanced in recent years, presumably as a result of selection pressure to cross the Sahel before its seasonal dry period. In contrast, migrants wintering north of the Sahara have delayed autumn passage. In addition, species with a variable rather than a fixed number of broods per year have delayed passage, possibly because they are free to attempt more broods. Recent climate changes seem to have a simple unidirectional effect on the seasonal onset of reproduction, but complex and opposing effects on the timing of subsequent events in the annual cycle, depending on the ecology and life history of a species. This complicates predictions of overall effects of global warming on avian communities

Data from: Use of classical bird census transects as spatial replicates for hierarchical modeling of an avian community

New monitoring programs are often designed with some form of temporal replication to deal with imperfect detection by means of occupancy models. However, classical bird census data from earlier times often lack temporal replication, precluding detection-corrected inferences about occupancy. Historical data have a key role in many ecological studies intended to document range shifts, and so need to be made comparable with present‐day data by accounting for detection probability. We analyze a classical bird census conducted in the region of Murcia (SE Spain) in 1991 and 1992 and propose a solution to estimating detection probability for such historical data when used in a community occupancy model: the spatial replication of subplots nested within larger plots allows estimation of detection probability. In our study, the basic sample units were 1‐km transects, which were considered spatial replicates in two aggregation schemes. We fit two Bayesian multispecies occupancy models, one for each aggregation scheme, and evaluated the linear and quadratic effect of forest cover and temperature, and a linear effect of precipitation on species occupancy probabilities. Using spatial rather than temporal replicates allowed us to obtain individual species occupancy probabilities and species richness accounting for imperfect detection. Species‐specific occupancy and community size decreased with increasing annual mean temperature. Both aggregation schemes yielded estimates of occupancy and detectability that were highly correlated for each species, so in the design of future surveys ecological reasons and cost‐effective sampling designs should be considered to select the most suitable aggregation scheme. In conclusion, the use of spatial replication may often allow historical survey data to be applied formally hierarchical occupancy models and be compared with modern‐day data of the species community to analyze global change process

Avian community data

Matrix corresponding to sites and avian species for the aggregation schemes AS2x2 and AS3x3. A total of 73 avian species were recorded in 1-km spatial transects. The number of spatial replicates (J) for each site where the species was observed and the different covariates for each site: the percentage of forest cover (forest), the annual mean temperature (temp) and the anual precipitation (prec)

Data from: Evaluating temporal turnover in avian species richness in a Mediterranean semiarid region: different responses to elevation and forest cover

<p><span><strong>Aim</strong>.</span><span> When studying the effects of global change on biodiversity, it is far more common for the effects of climate change and land-use changes to be assessed separately rather than jointly. However, the effects of land-use changes in recent decades on species richness in areas affected by climate change have been less studied. </span><span>We assess the temporal turnover in species richness of an avian community between a historical period and a modern one as a consequence of global change.</span></p> <p><span><strong>Location</strong>. </span><span>Semiarid Mediterranean ecosystem (Southeastern Spain). </span></p> <p><span><strong>Method</strong>.</span><span> We fitted a hierarchical multi-species occupancy </span><span>model for each period (</span><span>1991-1992, and 2012-2017)</span><span>, obtaining avian species-specific estimates of occupancy probability in relation to environmental covariates </span><span>(elevation and forest cover)</span><span>. </span><span>We analyze the relationships between changes in the bird community and environmental variables, analysing the temporal turnover of the species richness and the richness-based species-exchange ratio.</span> </p> <p><span><strong>Results</strong>.</span> <span>The estimated species richness accounting for detectability was higher than observed species richness, and decreased in the </span><span>more recent </span><span>period. Following our hypotheses, we observed a dual pattern of species richness increase associated with different elevations, showing different species turnover rates due to the joint effects of climate change and land-use change. There is a trend toward greater species richness with higher elevations that is associated with climate change, where the species turnover rate is low. Also, species richness increased towards lower elevations, but with a high turnover rate. The latter can be due to species expansions through</span><span>ou</span><span>t new habitat configurations in bordering forest systems associated with anthropic land-use changes. </span></p> <p><span><strong>Conclusions</strong>.</span><span> Our study is of great interest to understand the temporal turnover of avian species richness associated with areas experiencing both climate and land-use change.</span></p><p>Funding provided by: Spanish Ministry of Economy and Competitiveness*<br>Crossref Funder Registry ID: <br>Award Number: IJC2019-039145-I</p><p><span>This field work was developed as a basis for assessing the state of the region's forest heritage and the effects of global change on its biodiversity</span><span>, concentrated in two periods: a "historical period" (years 1991 and 1992) and a "modern period" (years 2012 and 2017). The survey protocol was characterized by transects of 1 kilometer length, which were distributed across all the forested areas in the study area in a random fashion and were surveyed once during a breeding period (May-July)</span><span>. Each transect survey was conducted by walking and recording the number of each species detected (by sight or song/call) along it. A total of 377 1-km transects were conducted for the historical period as part of a forestry plan in the region, developing a new avian survey of 198 transects with a similar protocol for the modern period.</span></p> <p><span>We considered the 1-km transects of each bird survey as nested within a "site", i.e., as spatial observations replicated within the site, thus enabling estimation of detection probability in an occupancy model</span><span>. We defined sites as cells in a grid that covers our study area</span><span>. We selected cell size to be 2x2 km, based on the species in our bird community (most of them passerines with small home ranges</span><span>)</span><span>, which may be suitable for evaluating the effects of environmental covariates on bird species occupancy at a regional scale</span><span>. </span><span>Therefore, a total of 377 and 198 1-km spatial transects were conducted and grouped in 226 and 139 sites for the historical and modern periods, respectively. </span></p&gt