The Population Numbers Challenge

2017 ◽  
pp. 20-28
Keyword(s):  
Population Numbers

Use of Population Numbers to Estimate Feed Allowances for Trout

1970 ◽  
Vol 32 (2) ◽  
pp. 97-100
Author(s):  
Earl A. Pyle ◽  
Olber L. Ray
Keyword(s):  
Population Numbers

Effects and importance of indigenous earthworms on decomposition and nutrient cycling in coastal forest ecosystems

1986 ◽  
Vol 16 (5) ◽  
pp. 983-989 ◽  
Author(s):  
G. A. Spiers ◽  
D. Gagnon ◽  
G. E. Nason ◽  
E. C. Packee ◽  
J. D. Lousier
Keyword(s):  
Forest Ecosystems ◽  
Coastal Forest ◽  
Mixed Stands ◽  
Earthworm Casts ◽  
Earthworm Species ◽  
Podzolic Soils ◽  
Availability Analysis ◽  
High Nutrient ◽  
Organic Horizons ◽  
Population Numbers

The general ecology of an undescribed indigenous earthworm species in the Megascolecidae, found in the organic horizons of Podzolic soils under mixed stands of Tsugaheterophylla, Abiesamabilis, Thujaplicata, and Pseudotsugamenziesii, is described. The earthworm is a member of the genus Arctiostrotus. Over a range of sites, population numbers of earthworms were correlated to rooting concentration in and immediately below the mor humus. By micromorphological examination, earthworm casts were found to account for up to 60% by volume of the constituent solids of the organic horizons. The abundance of both fine roots and fungal hyphae in the worm casts suggested high nutrient availability. Analysis of fresh faecal material showed a marked increase in most important nutrients (N, P, K, Mg, Fe, Na) relative to levels in noningested litter. Observations indicate that this earthworm species, whose population density may reach 200 m−2, has a major role in the decomposer subsystem of these ecosystems.

scholarly journals Estimating Otter Numbers Using Spraints: Is It Possible?

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Paul Yoxon ◽  
Kirsty Yoxon
Keyword(s):  
Seasonal Variation ◽  
Standard Methodology ◽  
Set Up ◽  
The Uk ◽  
Population Numbers

Spraints have been used to survey otters in the UK since 1979 and a standard methodology has been set up which has been used in Britain and Europe for most survey work. At present data from these surveys is being used to give an estimation of actual population numbers. However, for this to be possible, there must be a correlation between sprainting numbers, active spraint sites, and otter numbers. This paper investigates whether such a correlation exists. There is evidence from previous work that there is seasonal variation in sprainting and this study confirms this. Therefore spraint surveys should be undertaken in the same months for each repeat survey.

The impact of the German frontier on the economic development of the countryside of Roman Gaul

2018 ◽  
Vol 31 ◽  
pp. 131-160 ◽  
Author(s):  
Michel Reddé
Keyword(s):  
Economic Development ◽  
Regional Scale ◽  
Rural Settlements ◽  
Modern Times ◽  
Roman Economy ◽  
Agricultural Yield ◽  
The Impact ◽  
The Relationship ◽  
European Programme ◽  
Population Numbers

In a series of studies about settlement density in the Rhine area from protohistoric to modern times, K.-P. Wendt and A. Zimmermann try their hand at the difficult task of evaluating the palaeodemography of a region. Their task is all the more complex because these are times and spaces for which written sources are lacking, as a result of which reasoning relies very broadly on interpretation of the archaeological record. The two researchers also attempt to characterize the density of rural settlements and their spatial distribution. I shall not dally on the methods employed, which involve quite complex statistics and geomatics (anyway, they lie outside my area of scientific competence), and shall take the figures at face value, even if I might question some of them. I shall contemplate the economic impact of population growth on the countryside of Gaul in Imperial times. It is a subject that has often been addressed, but one which I intend to reconsider in the context of a European programme on this issue. The relationship between population numbers, agricultural yield, gross domestic product and taxation has certainly been one key to our understanding of the Roman economy ever since the model suggested by K. Hopkins. Here, however, I do not wish to proceed in terms of theory, but intend to review critically the archaeological sources, which, for want of written evidence, are our mainspring for evaluating the key components of economic development on the regional scale of NE Gaul.

scholarly journals Agrochemical synergism imposes higher risk to Neotropical bees than to honeybees

2017 ◽  
Vol 4 (1) ◽  
pp. 160866 ◽  
Author(s):  
Hudson V. V. Tomé ◽  
Gabryele S. Ramos ◽  
Micaele F. Araújo ◽  
Weyder C. Santana ◽  
Gil R. Santos ◽  
...  
Keyword(s):  
Apis Mellifera ◽  
Stingless Bees ◽  
Synergistic Effects ◽  
Stingless Bee ◽  
Key Factors ◽  
Thiophanate Methyl ◽  
Africanized Honeybee ◽  
Modes Of Action ◽  
Population Numbers

Bees are key pollinators whose population numbers are declining, in part, owing to the effects of different stressors such as insecticides and fungicides. We have analysed the susceptibility of the Africanized honeybee, Apis mellifera , and the stingless bee, Partamona helleri, to commercial formulations of the insecticides deltamethrin and imidacloprid. The toxicity of fungicides based on thiophanate-methyl and chlorothalonil were investigated individually and in combination, and with the insecticides. Results showed that stingless bees were more susceptible to insecticides than honeybees. The commercial fungicides thiophanate-methyl or chlorothalonil caused low mortality, regardless of concentration; however, their combination was as toxic as imidacloprid to both species, and over 400-fold more toxic than deltamethrin for A. mellifera . There were highly synergistic effects on mortality caused by interactions in the mixture of imidacloprid and the fungicides thiophanate-methyl, chlorothalonil and the combined fungicide formulation in A. mellifera, and also to a lesser extent in P. helleri . By contrast, mixtures of the deltamethrin and the combined fungicide formulation induced high synergy in P. helleri , but had little effect on the mortality of A. mellifera . Differences in physiology and modes of action of agrochemicals are discussed as key factors underlying the differences in susceptibility to agrochemicals.

scholarly journals Estimating population size of the cave shrimp Troglocaris anophthalmus (Crustacea, Decapoda, Caridea) using mark–release–recapture data

2015 ◽  
Vol 38 (1) ◽  
pp. 77-86
Author(s):  
J. Jugovic ◽  
◽  
E. Praprotnik ◽  
E. V. Buzan ◽  
M. Luznik ◽  
...  
Keyword(s):  
Population Size ◽  
Aquatic Invertebrates ◽  
Anthropogenic Activities ◽  
Age Distribution ◽  
Mark Release Recapture ◽  
Population Size Estimates ◽  
Cave Ecosystems ◽  
Size Estimates ◽  
Abundant Population ◽  
Population Numbers

Population size estimates are lacking for many small cave–dwelling aquatic invertebrates that are vulnerable to groundwater contamination from anthropogenic activities. Here we estimated the population size of freshwater shrimp Troglocaris anophthalmus sontica (Crustacea, Decapoda, Caridea) based on mark–release–recapture techniques. The subspecies was investigated in Vipavska jama (Vipava cave), Slovenia, with estimates of sex ratio and age distribution. A high abundance of shrimps was found even after considering the lower limit of the confidence intervals. However, we found no evidence of differences in shrimp abundances between summer and winter. The population was dominated by females. Ease of capture and abundant population numbers indicate that these cave shrimps may be useful as a bioindicator in cave ecosystems.

scholarly journals Ecology of the Anthropocene signals hope for consciously managing the planetary ecosystem

2021 ◽  
Vol 118 (28) ◽  
pp. e2024150118
Author(s):  
Clarence Lehman ◽  
Shelby Loberg ◽  
Michael Wilson ◽  
Eville Gorham
Keyword(s):  
Population Growth ◽  
Cultural Evolution ◽  
Human Population ◽  
Human Populations ◽  
Present Moment ◽  
Minimal Set ◽  
The Past ◽  
Food Species ◽  
Large Predators ◽  
Population Numbers

Human populations have grown to such an extent that our species has become a dominant force on the planet, prompting geologists to begin applying the term Anthropocene to recognize the present moment. Many approaches seek to explain the past and future of human population growth, in the form of narratives and models. Some of the most influential models have parameters that cannot be precisely known but are estimated by expert opinion. Here we apply a unified model of ecology to provide a macroscale summary of the net effects of many microscale processes, using a minimal set of parameters that can be known. Our models match estimates of historic and prehistoric global human population numbers and provide predictions that correspond to some of the more complicated current models. In addition to fitting the data well they reveal that, amidst enormous complexity in our human and prehuman past, three key ecological discontinuities have occurred in turn: 1) becoming dominant competitors of large predators rather than their prey, 2) becoming mutualists with food species rather than acting as predators upon them, and 3) changing from a regime of uncontrolled population growth to one of controlled fertility instead. All three processes have been interlinked with cultural evolution and all three ushered in developments of the Anthropocene. Understanding the trajectories that have delivered us to this stage can help guide prudent paths into the future.

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