ESTIMATING ADULT COCCINELLID POPULATIONS IN WHEAT FIELDS BY REMOVAL, SWEEPNET, AND VISUAL COUNT SAMPLING

1991 ◽  
Vol 123 (1) ◽  
pp. 13-22 ◽  
Author(s):  
N.C. Elliott ◽  
R.W. Kieckhefer ◽  
W.C. Kauffman
Keyword(s):  
Population Density ◽  
Regression Models ◽  
Population Densities ◽  
Density Estimates ◽  
Aphid Density ◽  
Absolute Density ◽  
Density Values ◽  
Removal Sampling ◽  
Density Population ◽  
Absolute Population

AbstractRemoval sampling, sweepnet sampling, and visual count sampling conducted while walking at constant velocity through a field were used to sample populations of adults of five coccinellid species in plots established in spring wheat fields, Triticum aestivum L. Estimates of absolute population density obtained from two 20-min removal samples taken from each of six 5- by 5-m sub-plots per plot proved reliable and were used to convert estimates obtained from sweepnet sampling (180 sweeps per plot) and visual counts (36 min per plot walking at 10 m/min) into absolute estimates of population density. Population density estimates obtained by removal sampling were quite precise except for species with low capture efficiencies and low population densities.Crop plant growth stage influenced the numbers of beetles caught in sweepnet samples and was incorporated in regression models for converting sweepnet catch to absolute density. Values of R2 of regressions ranged from 0.51 to 0.90, depending on species. Visual counts were influenced by temperature and aphid density, and these variables were incorporated in regression models. Values of R2 for regressions relating visual counts to population densities ranged from 0.63 to 0.94, depending on species.

USING RADIOCARBON DATA TO CHRONOLOGICALLY CONTROL POPULATION DENSITY ESTIMATES DERIVED FROM SYSTEMATICALLY COLLECTED INTRA-SETTLEMENT DISTRIBUTIONAL DATA

Radiocarbon ◽  
2020 ◽  
pp. 1-21
Author(s):  
Brandon T Ritchison
Keyword(s):  
Population Density ◽  
Important Variable ◽  
Archaeological Sites ◽  
Archaeological Record ◽  
Population Densities ◽  
Density Estimates ◽  
Archaeological Material ◽  
Radiocarbon Data ◽  
Regional Population ◽  
Fine Time

ABSTRACT Population density is an important variable in the development of social complexity. Estimating population densities from the archaeological record requires combining estimates of population, area, and time. Archaeological population estimates tend to be reported as a maximum population derived from the total accumulation of discrete archaeological material types, usually ceramics or radiocarbon (14C) dates. However, given the palimpsest nature of the archaeological record at recurrently occupied archaeological sites, these maximal, total estimates are, at best, a poor reflection of contemporaneous populations. I present a method for calculating average yearly population densities for occupations at a large, multicomponent site using a combination of distributional data and 60 14C dates. By employing this method at other sites in the same region, modeling intra-regional population dynamics at fine time scales will be possible.

scholarly journals Carrying capacity, population density and the later Pleistocene expression of backed artefact manufacturing traditions in Africa

2020 ◽  
Vol 376 (1816) ◽  
pp. 20190716 ◽  
Author(s):  
W. Archer
Keyword(s):  
Population Density ◽  
Homo Sapiens ◽  
Behavioural Change ◽  
Archaeological Sites ◽  
Cultural Complexity ◽  
Density Estimates ◽  
Site Density ◽  
Independent Population ◽  
Density Population ◽  
Stone Artefact

As is the case today, both climate variability and population density influenced human behavioural change in the past. The mechanisms underpinning later Pleistocene human behavioural evolution, however, remain contested. Many complex behaviours evolved in Africa, but early evidence for these behaviours varies both spatially and temporally. Scientists have not been able to explain this flickering pattern, which is present even in sites and regions clearly occupied by Homo sapiens . To explore this pattern, here the presence and frequency of evidence for backed stone artefact production are modelled against climate-driven, time-series population density estimates (Timmermann and Friedrich. 2016 Nature 538 , 92. ( doi:10.1038/nature19365 )), in all known African Late Pleistocene archaeological sites ( n = 116 sites, n = 409 assemblages, n = 893 dates). In addition, a moving-window, site density population estimate is included at the scale of southern Africa. Backed stone artefacts are argued in many archaeological contexts to have functioned in elaborate technologies like composite weapons and, in the African Pleistocene, are accepted proxies for cultural complexity. They show a broad but sporadic distribution in Africa, prior to their association with Homo sapiens dispersing into Europe 45–40 ka. Two independent population estimates explain this pattern and potentially implicate the interaction of climate change and demography in the expression of cultural complexity in African Pleistocene Homo sapiens . This article is part of the theme issue ‘Cross-disciplinary approaches to prehistoric demography’.

scholarly journals Evaluating Alternative Flight Plans in Thermal Drone Wildlife Surveys—Simulation Study

2021 ◽  
Vol 13 (6) ◽  
pp. 1102
Author(s):  
Julia Witczuk ◽  
Stanisław Pagacz
Keyword(s):  
Computer Simulations ◽  
Survey Design ◽  
Distance Sampling ◽  
Line Of Sight ◽  
Density Estimates ◽  
Accuracy And Precision ◽  
Survey Costs ◽  
Random Survey ◽  
Density Population

The rapidly developing technology of unmanned aerial vehicles (drones) extends to the availability of aerial surveys for wildlife research and management. However, regulations limiting drone operations to visual line of sight (VLOS) seriously affect the design of surveys, as flight paths must be concentrated within small sampling blocks. Such a design is inferior to spatially unrestricted randomized designs available if operations beyond visual line of sight (BVLOS) are allowed. We used computer simulations to assess whether the VLOS rule affects the accuracy and precision of wildlife density estimates derived from drone collected data. We tested two alternative flight plans (VLOS vs. BVLOS) in simulated surveys of low-, medium- and high-density populations of a hypothetical ungulate species with three levels of effort (one to three repetitions). The population density was estimated using the ratio estimate and distance sampling method. The observed differences in the accuracy and precision of estimates from the VLOS and BVLOS surveys were relatively small and negligible. Only in the case of the low-density population (2 ind./100 ha) surveyed once was the VLOS design inferior to BVLOS, delivering biased and less precise estimates. These results show that while the VLOS regulations complicate survey logistics and interfere with random survey design, the quality of derived estimates does not have to be compromised. We advise testing alternative survey variants with the aid of computer simulations to achieve reliable estimates while minimizing survey costs.

Effects of crop sequence and rainfall on population dynamics of Fusarium solani f.sp. phaseoli in soil

1992 ◽  
Vol 70 (10) ◽  
pp. 2005-2008 ◽  
Author(s):  
Robert Hall ◽  
Lana Gay Phillips
Keyword(s):  
Population Dynamics ◽  
Phaseolus Vulgaris ◽  
Population Density ◽  
Fusarium Solani ◽  
Population Densities ◽  
Total Rainfall ◽  
Colony Forming Units ◽  
Bean Crop ◽  
Previous Summer ◽  
Crop Sequence

Evidence is presented that population dynamics of Fusarium solani f.sp. phaseoli in soil depend on the effects of crop sequence and rainfall on parasitic activities of the pathogen. In a rotation trial started in 1978 and conducted over 14 years, population densities (colony-forming units/g) of the fungus in soil remained below 50 in treatments (fallow, repeated corn, repeated soybean) where the preferred host plant (common bean, Phaseolus vulgaris) was not grown. Where bean was grown every 3rd year or every year, population densities reached 475 and 660, respectively, by 1984. Thereafter, population densities of the fungus fluctuated widely from year to year in both rotation and repeated bean treatments. In the rotation treatment, peaks in population density of the pathogen coincided with the years of bean production. In repeated bean plots between 1985 and 1991, population density of the fungus in June was significantly correlated (r = 0.77, p = 0.04) with total rainfall received during the previous summer (June–August). It is postulated that higher rainfall during the growing season of the bean crop stimulated root growth and root infection, leading to the accumulation of higher levels of potential inoculum in infected tissue and the release of higher levels of inoculum into the soil by the following June. Key words: Fusarium solani f.sp. phaseoli, bean, Phaseolus vulgaris, rainfall, crop rotation.

Population Densities Allowed Around Dutch SEVESO Establishments

2000 ◽  
Author(s):  
G. M. H. Laheij ◽  
B. J. M. Ale ◽  
J. G. Post
Keyword(s):  
Population Density ◽  
The Netherlands ◽  
Individual Risk ◽  
Population Densities ◽  
Planning Policy ◽  
Relative Contribution ◽  
Societal Risk ◽  
Dangerous Substances ◽  
The Individual ◽  
Uniform Population

Abstract In the Netherlands, the individual risk and societal risk are used in efforts to reduce the number of people exposed to the effect of an accident at an establishment with dangerous substances. To facilitate the societal risk planning policy an investigation was carried out for the Dutch SEVESO establishments to investigate the possibility of determining a generic uniform population density for the zone between the individual risk contours of 10−5 and 10−6 per year. The indicative limit for the societal risk at this density was not to be exceeded. Also there was to be enough space left for a significantly higher population density outside the individual risk contour of 10−6 per year. The RORISC methodology and the actual data for the 124 Dutch SEVESO establishments were used to determine the generic uniform population density. Based on the data available it can be concluded that the maximum allowed uniform population density in the zone between the individual risk contours of 10−5 and 10−6 per year is lower than one person per hectare. At this density there is no space left for a higher population density outside the individual risk contour of 10−6 per year. For uniform population densities the relative contribution to the societal risk has been found significant up to the individual risk contour of 10−7 per year.

Density and activity patterns of ocelot populations in Yasuní National Park, Ecuador

Mammalia ◽  
2016 ◽  
Vol 80 (4) ◽  
Author(s):  
Julia Salvador ◽  
Santiago Espinosa
Keyword(s):  
Population Density ◽  
Habitat Loss ◽  
National Park ◽  
Conservation Status ◽  
Activity Patterns ◽  
Camera Trap ◽  
Oil Extraction ◽  
Density Estimates ◽  
Yasuni National Park ◽  
Ecuadorian Amazon

AbstractOcelots were historically hunted for their skins but habitat loss is now their most serious threat, causing rapid declines in populations throughout their range. Ocelot abundance has been estimated for various locations across the Neotropics, but we still lack this information from some countries, including Ecuador. Knowing whether ocelot abundance is increasing or decreasing is important to assess the conservation status of this species and the conditions of its habitats in the Ecuadorian Amazon and in the region. To determine whether ocelot abundance and its behavior are affected by human-related activities, camera-trap surveys were carried out in two localities of Yasuní National Park (YNP), one that has experienced hunting, oil extraction, and roads (Maxus Road) and one that is largely unaffected by these activities (Lorocachi). During the survey, 35 and 36 individual ocelots were photographed in Maxus Road and Lorocachi, respectively. Population density estimates were similar for both localities, ranging from 0.31 (SE±6) to 0.85 (SE±17) ocelots/km

scholarly journals Effects of population density on cauliflower crop (Brassica oleracea L. var. botrytis)

1981 ◽  
Vol 38 (1) ◽  
pp. 1-10
Author(s):  
Keigo Minami ◽  
Ricardo Victoria Fº
Keyword(s):  
Population Density ◽  
Brassica Oleracea ◽  
Plant Population ◽  
Population Densities ◽  
Plant Population Density ◽  
Brassica Oleracea L ◽  
Quality Weight

An experiment was carried out to study the effects of the following population densities cauliflowers (plants per ha): 20,833 (0.60 m x 0.80 m), 25,641 (0.60 m x 0.65 m), ....37.037 (0.60 m x 0.45 m) , 55.555 (.0.60 m x 0.30 m), and 111,111 (0,60 m x 0,15 m) ; variety Snow ball. It was concluded that the effects of plant population density are greater on curd quality (weight and size) than on production per ha. The best plant population density to produce cauliflowers curd for Brazil market is from 20,000 to 25,000 plants/ha while for mini-curd is above 55,000 plants/ha.

scholarly journals Youth Crime in Colombia

2020 ◽  
Vol 26 (105) ◽  
pp. 131-154
Author(s):  
Luis Eduardo Sandoval-Garrido ◽  
Keyword(s):  
Young People ◽  
Population Density ◽  
Criminal Activity ◽  
Urban Crime ◽  
Political Polarization ◽  
Youth Crime ◽  
Proposed Model ◽  
Juvenile Population ◽  
Youth Population ◽  
Density Population

In some countries, the increase in the youth population is connected to greater criminal activity. In the case of Colombia, different studies support the idea of providing socio-economic possi-bilities for young people to avoid being linked to illegal and criminal activities. Based on these precedents, this document examines whether the increase in the youth population in Colombia is directly connected to municipal crime during 2000-2010, a period in which those born in the 1990’s reached their teenage years and could participate in urban crime. For this study, economic and other variables of total and juvenile population are constructed for youth between the ages of 15-24, as well as variables in population density and political polarization incorporating the crime index proposed by (Durán, López, & Restrepo, 2009). The proposed model estimates that youth population density, population growth, conflict actions and political polarization are asso-ciated with an increase in crime. Also, greater development and political polarization can lead to an environment of less crime.

scholarly journals Using Astragalus to Model Body Mass, Habitat Preference, and Population Density of Prehistoric Bovid Duboisia santeng (Dubois, 1891) in Eastern Java island in The Early Pleistocene

2020 ◽  
Author(s):  
Andri Wibowo
Keyword(s):  
Population Density ◽  
Body Mass ◽  
Habitat Preference ◽  
Regression Models ◽  
The Body ◽  
Early Pleistocene ◽  
Large Herbivores ◽  
Length Width ◽  
Fossil Records ◽  
The Relationship

Astragalus bone is one of the most important fossil records as it can reconstruct the prehistoric life. Respectively, this study aims to model the body mass, habitat preference, and population density of prehistoric bovid Duboisia santeng (Dubois 1891) in eastern Java island in the early Pleistocene. The astragali from 9 specimens were used to estimate the body mass and population density. Likewise regression models are used to analyze the relationship between astragalus lateral length, width, and body mass compared to the astragalus of extant Bovid species. The result revealed the body mass average was 60.3 kg (95%CI: 58.9-61.7) and this indicates the D. santeng belongs to large herbivores. While the population density was estimated at about 5.39 individuals per km2 (95% CI: 3.18-7.6).

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