Years Of Censuses Research Articles

Fifty years of spring censuses in black grouse (Lyrurus tetrix) in the High Fens (Belgium): did the rabies vaccination has a negative impact on a fox prey population?

The online version contains supplementary material available at 10.1007/s10344-023-01642-w.

Genet dynamics and its variation among genets of a clonal plant Convallaria keiskei

In clonal plant populations, a number of genetically identical ramets form a genet. While coexisting ramets potentially perform independently, their behaviours not only depend on ages and sizes but are also constrained by genetic background. In this study, genet dynamics and its variability among neighbouring genets were investigated based on the ramet demography of each genet in Convallaria keiskei. Genet dynamics were first formulated as a matrix model with the two components of clonal growth (clonal reproduction) and survival‐transitions between ramet size classes. Then, a statistical estimation of the matrix elements was established using three datasets: aboveground demographic censuses, belowground directional rhizome connections and genetic identification of ramets. Finally, genet growth rates reflecting both the changes of clonal growth and ramet size growth were estimated and compared for fundamental demographic elements among genets. Over three years of aboveground annual censuses of a 28 × 2 m plot, 2021 ramets were identified as belonging to 28 genotypes. Belowground excavation detected 515 clonal fragments. Genet growth rate of three dominant genets varied with medians of 1.13, 1.02 and 1.05; 95% credible intervals of the posterior distributions did not overlap between the genet with the largest median and the others. The variation was caused primarily by differences in clonal growth rather than survival‐transitions between size classes. Clonal growth by branching was rarer than at the tips but contributed to the maintenance of the genet. Therefore, both clonal growth frequencies and connecting patterns of ramets caused the variation of genet dynamics and established genets persist for a long time through the positive growth rates, which would contribute to maintain a population. We also conclude that fundamental demographic elements relating to clonal growth traits (the features of individual genets) strongly impact genet dynamics.

Long-Term Changes in Breeding Bird Community of a Primeval Temperate Forest: 45 years of Censuses in the Białowieża National Park (Poland)

This paper reports the long-term numerical trends of the thirty common forest bird species and explores changes in the community composition in the three main types of old-growth stands in the Białowieża National Park (E Poland, hereafter BNP) over 45 years (1975–2019). We present recent (2015–2019) data on abundance of birds for the seven study plots and pool them with the time series collected since 1975. The numbers of individual bird species strongly fluctuated, with most of the species showing alternating phases (the initial periods of population growth followed by the periods of population decline or stability). The numbers of 19 species increased; maximum growths by c. 3–5% per year included Columba palumbus, Dendrocopos major, Sylvia atricapilla and Regulus ignicapilla. Among a few declining species, Ficedula hypoleuca, Phylloscopus sibilatrix and F. parva experienced the strongest declines, respectively by 4.0%, 2.7% and 2.2% per year. Mostly the same species bred in the plots in the 1970s and in recent years, indicating a stable species pool. The total abundance peaked around 2005, declining thereafter in deciduous stands, but increasing further (along with the species richness) in the coniferous stands. The similarity index between the study plots (beta-diversity) changed little over 45 years; ash-alder and lime-hornbeam stands remained most similar, while coniferous forests stood more apart. The changes found in the old-growth stands of BNP (mostly coniferous fragments) could be partly explained by natural modification of the habitat structure and the processes acting in the large geographical scales, within or outside of the breeding grounds. The long-term studies such as the one in the BNP reported here, provide a basis for the rates of natural turnover in the bird communities in pristine habitats, directly unaffected by human impact.

Cascading effects of sand stabilization on pathogen communities: Connecting global and local processes

AbstractAimTo advance our understanding of the mechanisms that mediate the relationships between global climatic and anthropogenic processes and pathogen occurrence, it is crucial to evaluate the exact pathways connecting the ecological mediators and the pathogen responses across spatial and temporal heterogeneities at various scales. We investigated the pathways connecting these two types of heterogeneities in sand stabilization that were created by contrasting forces of various human activities and long‐term droughts, and pathogen occurrence in host populations. The considered candidate ecological mediators were various components of host community structure, arthropod vector traits, and the pathogen occurrence in these vectors.LocationNorth‐western Negev Desert's sands in Israel.Time period1982–2018.Major taxa studiedGerbillus andersoni, Gerbillus floweri, Gerbillus gerbillus, Mycoplasma, Bartonella, Synosternus cleopatrae.MethodsWe combined information from satellite images, 36 years of rodent censuses, a natural experiment, and causal modelling.ResultsWe found evidence that the spatial heterogeneity in sand biocrusts is largely correlated with structural differences between host communities, especially at medium spatial scales. Pathogen sampling, followed by causal modelling, suggested that the cascading effect of sand stabilization on pathogen occurrence is mainly mediated through changes in host community structure and vector burdens. Importantly, we found that structural changes in the same host community can simultaneously amplify and dilute different pathogens.Main conclusionsThese findings suggest that global processes can translate into local processes, where the importance of the mediation effects depend on the magnitude of environmental heterogeneity. These mediation effects can benefit some organisms while adversely affecting others.

Soil denudation rates in an old‐growth mountain temperate forest driven by tree uprooting dynamics, Central Europe

AbstractTree uprooting may distinctly affect landscape dynamics and slope denudation. Little is known, however, about the corresponding soil redistribution rates (erosion and accumulation) on either a long‐term (millennia;10Be) or a short‐term (decades;239+240Pu) scale. We determined these rates in a well‐investigated forest reserve (Zofinsky primeval forest, Czech Republic) using complementary techniques: nuclides in soils and tors to derive short‐ to long‐term rates and monitoring data (43 years) of repeated tree censuses using tree uprooting data. Temporal trends of soil erosion rates were obtained by dating the timing of exhumation (10Be) of tors. The average long‐term denudation rates were about 30–40 t km−2yr−1. It seems that these rates varied over time with probably a maximum during the Pleistocene/Holocene transition (58–91 t km−2yr−1).239+240Pu activities in the soils identified soil redistribution rates of 50 to >100 t km−2yr−1for the last decades and agree with results from the tree uprooting monitoring (<92 t km−2yr−1). In‐situ10Be in soils gave similar denudation rates (58–76 t km−2yr−1). Meteoric10Be provided a mean residence time of a soil particle of 33–100 ka supporting the measured average long‐term erosion rates. Soil aggregates indicated stable physical conditions meaning that soil mass redistribution occurs only sporadically. It seems that the main driving factors of denudation changed over time. An erosion peak at the Pleistocene/Holocene transition (climate change) seems likely but needs further proof. Over the last few millennia, tree uprooting seems the main driver of soil erosion.

Species-specific responses to habitat conversion across scales synergistically restructure Neotropical bird communities.

Ecologists are increasingly exploring methods for preserving biodiversity in agricultural landscapes. Yet because species vary in how they respond to habitat conversion, ecological communities in agriculture and more natural habitats are often distinct. Unpacking the heterogeneity in species responses to habitat conversion will be essential for predicting and mitigating community shifts. Here, we analyze two years of bird censuses at 150 sites across gradients of local land cover, landscape forest amount and configuration, and regional precipitation in Costa Rica to holistically characterize species responses to habitat conversion. Specifically, we used Poisson-binomial mixture models to (1) delineate groups of species that respond similarly to environmental gradients, (2) explore the relative importance of local vs. landscape-level habitat conversion, and (3) determine how landscape context influences species' local habitat preferences. We found that species fell into six groups: habitat generalists, abundant and rare forest specialists, and three groups of agricultural specialists that differed in their responses to landscape forest cover, fragmentation, and regional precipitation. Birds were most sensitive to local forest cover, but responses were contingent on landscape context. Specifically, forest specialists benefitted most when local forest cover increased in forested landscapes, while habitat generalists exhibited compensatory dynamics, peaking at sites with either local or landscape-level forest, but not both. Our study demonstrates that species responses to habitat conversion are complex but predictable. Characterizing species-level responses to environmental gradients represents a viable approach for forecasting the winners and losers of global change and designing interventions to minimize the ongoing restructuring of Earth's biota.

Using a multi-model ensemble forecasting approach to identify key marine protected areas for seabirds in the Portuguese coast

Marine Protected Areas (MPAs) have been established across all marine environments, though their coherence and effectiveness in protecting umbrella species remains unclear. We used a multi-model ensemble forecasting approach, on 8 years of at-sea censuses of 30 seabird species to identify candidate MPAs in the Portuguese coast, prioritizing important areas for their conservation based on their occurrence and distribution. We overlapped the outputs generated by the Ensemble Ecological Niche Models (EENMs) with layers representing important environmental stressors (fishing intensity, ship density and oil pollution risk), and calculated loss in conservation value using them as cost layers. Three key marine areas were identified along the Portuguese coast: For breeders, there was a key marine area encompassing the Tagus and Sado estuaries and Berlengas archipelago; for non-breeders and migratory species two important areas were identified in the Northern and Southern coast. The key marine area identified in the Northern coast is characterized by high productivity and biodiversity, and can be affected by oil pollution from the refineries and the intensive ship traffic in this area. Also, the area identified in the Southern coast of Portugal for migratory seabirds overlaps extensively with areas of high fishing activity. Our results show that the Important Bird and Biodiversity Areas (IBAs) established along the Portuguese coast protect more than a third of the areas that we prioritized for breeding species and the official MPAs near 65% of the same areas. In contrast, current IBAs and national legislation protect less than 4% of the coastal areas that we prioritize for non-breeding species in this study. Our study, combining multi-species distribution with environmental constraints induced by human activities, allowed us to assess the coherence of the Portuguese marine planning and identify candidate areas to join the Portuguese network of marine protected areas. Our results, employing data from annual at-sea surveys together with the human stressors known to affect the Portuguese coast, proved to be an extremely useful strategy to identify spatial conservation areas along the Portuguese coast as well as to access the adequacy and consistency of those areas. Despite the constraints of this demanding approach, we are confident that our study provides a reliable strategy to inform marine conservation efforts and management planning in similar coastal environments elsewhere, characterized by strong coastal upwelling movements.

The dynamics of Kelp Forests in the Northeast Pacific Ocean and the relationship with environmental drivers

Abstract The dynamics of foundation species in ecosystems are key to the fate of many species. Kelp forests are foundation species in temperate ocean ecosystems and contribute to carbon storage, macronutrient dynamics, primary production and biodiversity of a myriad of associated species. Downward trends in their abundance globally have been of concern. We analysed 26 years of aerial censuses (1989–2015) of two canopy kelp species in Washington State (USA) waters. We compared these modern censuses with censuses in 1911 and 1912 to determine the persistence of kelp cover over the past century. Using Autoregressive Integrated Moving Average (ARIMA) models, we compared kelp dynamics with likely environmental drivers, including local environmental variables and ocean indices for this region. Kelp remains at historic levels in many areas, although some eastern populations in proximity to greater human populations are the exception to this pattern. Over the last 26 years, kelp abundance showed high spatial autocorrelation in western areas of Straits of Juan de Fuca, with more variable populations in the annual species and eastward towards Puget Sound. Both species covaried positively in their abundance throughout most of the study area, suggesting that environmental factors rather than competition, drove their dynamics. The population dynamics of these kelp species showed that the abundance 1 year previously was an important predictor, and cyclic dynamics were not indicated using ARIMA models. Kelp abundance correlated inversely with the Pacific Decadal Oscillation and the Oceanic Nino Index, and positively with the North Pacific Gyre Oscillation, indicating that large‐scale processes associated with colder seawater temperatures were associated with greater relative abundance of kelp. Synthesis. Kelp beds in the northern California Current Large Marine Ecosystem have mostly remained persistent over the past century and over many kilometres, but some areas may have decreased in abundance. The sensitivity of these populations to indices of ocean climate, our demonstration that a historic 93‐year sea surface temperature record (Race Rocks, Canada) showed a 0.72°C increase and the classification of some areas as high variability‐low abundance, suggest that the viability of these foundational species remain a concern into the future.

Disclosure of historical spatial and statistical data of districts in Czechia in a GIS environment

This article presents a methodology for the creation and reconstruction of historical borders of chosen spatial units, especially political and judicial districts in Czechia for the specific years of population censuses within a GIS environment. Since an ethnic, language, demographic, social and cultural composition of a population is one of the main features of national and regional identity, the main objective of the article is to introduce new method for the creation of spatial-statistical databases which will make these historical data sources accessible to both experts and the public for general use. For this purpose, district borders from 1921, 1930, (1947), 1950, 1961, 1970, 1991, 2001 and 2011, which represent the years of the population censuses in Czechia, were digitized. Our method is based mainly on historical maps, which correspond with the censuses’ statistical datasets. The proposed methodology for the creation of GIS layers (digitalization, geo-referencing, vectorization, accuracy assessment, and spatial identification), their connection with censuses statistical data (creation of spatial codes), metadata creation, and web publication is described in this article along with examples of some of the difficulties encountered during the process. We also bring attention to several case studies of problematic areas where the reconstruction of borders was particularly complicated. Finally, spatial and statistical data in the format of ESRI shapefile and ESRI Geodatabase offer possibilities for a retrospective analyses of quantitative data to current researchers from a range of scientific disciplines. Files in both formats are publicly available at webpage www.historickygis.cz.

Fifteen years of annual Cape Parrot Poicephalus robustus censuses: current population trends and conservation contributions

The Cape Parrot Poicephalus robustus is endemic to South Africa and numbers have reportedly declined since the early 1900s. It is a forest specialist and food nomadic, moving between patches depending on fruit availability. This makes it difficult to estimate numbers accurately and to determine its distribution. The annual Cape Parrot Big Birding Day was initiated in 1998 as a national census to determine a population estimate. Volunteers assist in monitoring and counting the Cape Parrot in the Eastern Cape, KwaZulu-Natal and Limpopo provinces in indigenous forests as well as sites where the parrots are known to feed outside of forests. Here, a summary of 15 years of census data is presented. In all years, with the exception of 2009, less than 1 600 Cape Parrots were recorded in the wild. The census data showed a slight increase in Cape Parrots, although this may be largely explained by an increase in coverage of suitable habitat and stabilisation in the population since 2005. A current distribution map for the Cape Parrot, based on census data, is presented. The distribution remains largely unchanged from that presented in the 1970s. This study highlights the value of public participation in monitoring an Endangered species and the need to conserve the forests where these parrots occur, due to their nomadic feeding behaviour.

Small-scale demographic compensation in a high-mountain endemic: the low edge stands still

Background: Under the current warming process, with its implications of higher temperatures, less rainfall, snowfall and snow cover, low-edge populations of high-mountain plants are expected to decline. Demographic studies are useful to foresee the future dynamics of species ranges. Adaptation, phenotypic plasticity, and demographic compensation have been proposed as mechanisms to cope with climate change. Aim: We studied the population dynamics of the high-mountain narrow endemic Armeria caespitosa at the extremes of its altitude distribution (low versus high edge), the high edge representing colonised summits that provide optimal growing conditions. The focus of the study was to establish if the species is retracting at its lower distribution range. Methods: We used 4 years of population censuses and soil seed bank data. Population matrix models allowed us to study the stochastic population growth rates, the species long-term viability under higher frequency of extreme years, and the life cycle transitions responsible for the differences in population dynamics between elevation range edges. Results: The low edge of the A. caespitosa elevation range appeared stable, with positive population growth rates under current environmental conditions, and a null quasi-extinction probability in the long-term under scenarios of high frequency of extremely dry years. Conclusions: The species will likely withstand the current climate-warming scenario along its elevation range. Results supported the role of so-called demographic compensation at a small spatial scale, which we argue might be common in the Mediterranean mountains.

Sex Ratio in Iran during a Period of Ten Years

Background: Sex or ratio between males and females is one of the demography characters of each population. It is important in genetic, health and medical studies to evaluate the situation of the public health of the societies. Sex ratios in each age group refer to the rate of mortality in that group. Comparison the sex ratios of an age group in two different times lead us to the reasons of its probable changes. Methods: In present work sex ratios among different age groups in Iran in the first and last year of a ten-year-period were determined and compared. Raw information was obtained from official documents of the two general censuses in 1986 and 1996. Results: Result showed that, in general, there was a decrease in sex ratios of groups 45 to 95 years in the year 1996 in comparison of the same results belong to the year 1986. In both years of general censuses in all three group populations (Urban, Rural and Nomads) the sex ratios gradually increased as well as the age groups. One of the most important results was that among rural and nomad population, the sex ratios have showed decrease, in fertility ages. Also, the sex ratios in young group 0-24 years (except the group 10-14 years) gradually have decreased, which showed the number of males is decreased. Conclusion : There was a decreasing trend in sex of male to female during the last three years in both urban and rural regions among all age groups.

Contrasting community compensatory trends in alternative successional pathways in central Amazonia

Based on eight years of annual censuses in secondary forests in central Amazonia, we compared successional dynamics in areas presenting alternative states due to different land use histories. Sites that had been clearcut without subsequent use are dominated by the pioneer genus Cecropia, but their understory is characterized by a diverse species assemblage. In contrast, areas clearcut and then used for pasture are dominated by the genus Vismia, forming nearly monogeneric stands. We evaluated whether such patterns were the outcome of differences in community compensatory trends, leading to a dynamic system of sequential replacement of species in Cecropia stands, and to a persistent stage of succession in Vismia stands. Floristic turnover in Cecropia stands showed strong and consistent negative frequency dependence. In contrast, Vismia stands exhibited little or no frequency dependence, likely due to local competitive interactions or priority effects. In these stands, species of the genera Vismia and Bellucia remained dominant throughout the monitoring period, whereas species initially of low abundance and frequency remained so. Differences in recruitment were the major driver of these alternative states. As species colonization proceeds, we expect dominance in the Vismia stands to diminish, albeit slowly. Our approach proved to be a useful tool for comparing species turnover in systems presenting alternative states.

Status and habitat requirements of Physaria thamnophila, an endangered species of Tamaulipan thornscrub

Abstract Physaria (Lesquerella) thamnophila (Brassicaceae; henceforth Physaria) is an endangered herbaceous perennial plant of remnant patches of Tamaulipan thornscrub near the southern Texas border. Six years of censuses of four populations of Physaria were analyzed. Quantitative data were collected to describe the plant community in the four sites. There was no overall trend in population size, but fluctuations in observed numbers of plants among years were extremely large: a single census cannot provide a reliable assessment of a population of this species. Seedling numbers were positively related with shrub canopy cover. However, there were many more Physaria plants in the brush-cleared portion of one site than in its uncleared portion. Seedling survival may be facilitated by anything that reduces movement of the highly erodible soils of these sites.

Can ground counts reliably monitor ibex Capra ibex populations

AbstractAlthough ground counts are often used to monitor ungulate populations, several studies show that counts of ungulates have low precision and often underestimate population size. We assessed the reliability of ibex Capra ibex counts as performed in French national parks, by analysing up to 23 years of annual censuses of six ibex populations for which a subset of animals were individually marked. We compared the population growth rate obtained from census data (estimated by use of four different methods) with the growth rate calculated from a demographic model including parameters estimated from capture‐mark‐recapture methods. The correlations between count‐based estimates and growth rate obtained from demographic models were adequate to suggest that ground counts can monitor trends in population size of ibex, provided that the occasional undercounts are identified. Substantial undercounts in some years led to biologically impossible values of yearly population growth (λ>1.35) and, in the longest time series available, to marked autocorrelations in counts. Managers should replicate counts within the same year to check for underestimated counts. To reduce errors, population biologists analysing time series of ungulate counts should check the plausibility of annual growth rates estimated from two consecutive counts.

CONCORDANCE BETWEEN SHORT-TERM EXPERIMENTS AND LONG-TERM CENSUSES IN TIDE POOL FISHES

Sixteen years of annual censuses (1990-2005) of an assemblage of tide pool sculpins at Tatoosh Island, Washington, USA, revealed relative constancy in the numbers of recruits and adults. However, the dominant species as a recruit (Clinocottus globiceps) was always replaced numerically as an adult by another species (Oligocottus maculosus). When mechanisms of coexistence were evaluated, little support was found for either a lottery model, because competitive interactions are hierarchical, or a storage-effect model of coexistence, because the relative ranking of recruitment varied little among years and did not covary among species with environmental variables such as ocean temperature, upwelling indices, or an estimator of ocean productivity (oyster condition index). There was also little evidence of niche partitioning based on habitat affinities. Additionally, predation-mediated coexistence had little support, given that the competitive dominant did not have the greatest rates of mortality. Instead, a competition-colonization trade-off may contribute to the coexistence of these species, where C. globiceps always recruits in the greatest numbers, while O. maculosus dominates the adult assemblage via competitive processes. The importance of post-recruitment processes in this assemblage is further suggested by some negative associations among species, the presence of density dependence, some habitat affinities, and previously published experimental work that demonstrated the competitive dominance of O. maculosus over C globiceps.

Protected cerrado fragments grow up and lose even metapopulational birds in central São Paulo, Brazil

Moderately dense woodland (cerradão) grew in two isolated patches of bushy savanna (cerrado) in central São Paulo over 23 years of bird censuses. Various uncommon birds were lost and some forest species were permanently gained. Fall and winter fruits attract long and short-distance migrants. Woodpeckers and some birds that nest in their holes seem to disappear during tree growth. Some birds in weedy areas nearby disappeared when the pastures replaced these areas, however sugar cane reduced the numbers of birds even more up to the point when some areas became pastures once more. Even travel-prone species disappear with vegetation growth in cerrado protected fragments, and therefore "metapopulations" may not survive over time, only in space.

Biodiversity, profitability, and vegetation structure in a Mexican coffee agroecosystem

We studied the relationships of bird and small mammal species richness, composition, and abundance to vegetation structure and economic profitability across a coffee intensification gradient in central Veracruz, Mexico. We conducted 2 years of point count censuses for summer resident birds, 2 years of Sherman live trapping for small mammals, and gathered vegetation structure data at 147 sampling points distributed over 16 sites spanning a cultivation intensification gradient. We calculated net annual revenue per hectare as an index of profitability from economic and management data collected during interviews with plantation owners/managers. Both the species richness and abundance of forest-affiliated birds were significantly greater in floristically and structurally diverse 'bajo monte' coffee and forest compared with commercial polyculture coffee, which was, in turn, significantly richer than statistically indistinguishable specialized shade and sun coffee. Mammal capture rates were extremely low at all but two sites. Forest bird species richness and abundance were explained by multiple linear regression models that included statistically significant effects of shade cover, percent of trees with epiphytes, and canopy height. We found no clear relationship between profitability and biodiversity, with biodiverse bajo monte coffee plantations ranking among the most profitable under all price scenarios. The high profitability of biodiverse bajo monte coffee systems was not dependent on the inclusion of long-term environmental costs or premium pricing systems. Our results demonstrate that high-biodiversity coffee cultivation can be compatible with high profitability, and has significant potential for conserving biodiversity in coffee-growing regions, but only as a substitute for low-biodiversity coffee cultivation, not forest.

Does coring contribute to tree mortality?

We assess the potential of increment coring, a common method for measuring tree ages and growth, to contribute to mortality. We used up to 21 years of annual censuses from two cored and two uncored permanent plots in the Sierra Nevada of California, to detect changes in mortality rates 12 years following coring for individuals >5 cm DBH from two coniferous species, Abies concolor (Gordon & Glend.) Lindl. (white fir) and Abies magnifica A. Murr. (red fir). Using a randomized before-after control impact (BACI) design, we found no differences in mortality rates following coring for 825 cored and 525 uncored A. concolor and 104 cored and 66 uncored A. magnifica. These results support the view that collecting tree cores can be considered nondestructive sampling, but we emphasize that our 12-year postcoring records are short compared with the maximum life-span of these trees and that other species in different environments may prove to be more sensitive to coring.

Ten years of censuses of fish fauna on the Loano artificial reef

In the period February 1989 to December 1998, the fish population on the Loano artificial reef (Ligurian Sea, Italy) was visually censused almost on a monthly basis (105 censuses). A total of 44 taxa were identified. Over the 10 years, species richness per census and the Shannon-Wiener diversity index gradually increased. The progressive evolution of the community has shown both the appearance of new species (Phycis phycis, Epinephelus marginatus, Muraena helena, Parablennius gattorugine) and the disappearance of others (Gobius cruentatus). Some species typical of hard substrata (Apogon imberbis, Scorpaena notata, Serranus cabrilla) have gradually increased in density over the 13 years since construction of the reef, indicating that stabilization of the community is a slow and long-term process. Copyright 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved.