scholarly journals A comparison of density estimation methods in plateau pika populations in an alpine meadow ecosystem

2020 ◽  
Vol 101 (4) ◽  
pp. 1091-1096
Author(s):  
Wanrong Wei ◽  
Jundong He ◽  
Qiaoyan Zheng ◽  
Yuli He ◽  
Maria K Oosthuizen
Keyword(s):  
Population Density ◽  
Relative Density ◽  
Alpine Meadow ◽  
Survey Methods ◽  
Estimation Methods ◽  
Plateau Pika ◽  
Relative Population ◽  
Burrow Density ◽  
The Absolute ◽  
Absolute Population

Abstract Plateau pikas are a keystone species and ecosystem engineers in alpine meadow ecosystems. A number of surveying methods have been used to estimate pika density, but the reliability of these methods is not known. In addition, better population density methodologies allow for more reliable density estimates. We therefore compared the relationship among several commonly used methods of estimating pika relative density and the absolute density (AD) of pika populations. This relationship was investigated in summer and winter pastures to determine whether distribution pattern of the pikas (patchy or uniform) would influence this relationship. During August of 2015 and August of 2016, we measured the relative and absolute population density of pikas in an alpine meadow in the County, Gansu province, northwestern China. Relative density was measured with three indirect and direct methods: the total burrow density (TBD), the active burrow density (ABD), and the direct counting density (DCD) at the peak of pika activity. AD was assessed by removal sampling. Our results showed that the relative population density with all three survey methods was significantly related to the absolute population density. In particular, DCD at the peak of the pika activity showed the best correlation with AD. A simple linear model showed the effect of grazing time by livestock had a significant effect on TBD and ABD. These results imply that using DCD as a method to survey at the peak of the pika activity is more reliable than other methods.

scholarly journals Community Structure of Gastropod in Seagrass on Intertidal Area in The Tongkeina Village of Manado City

2013 ◽  
Vol 1 (3) ◽  
pp. 102
Author(s):  
Gladys L Saripantung ◽  
Jan FWS Tamanampo ◽  
Gaspar Manu
Keyword(s):  
Community Structure ◽  
Population Density ◽  
Relative Density ◽  
Sampling Methods ◽  
Diversity Index ◽  
Intertidal Area ◽  
Gastropod Species ◽  
Relative Population ◽  
Study Sites ◽  
Index Value

ABSTRACT Gastropod community is one of the important components of the food chain in the seagrass beds. The purpose of this study is to identify the types of gastropods and to determine population density, relative population density, species diversity, dominance and species associations of gastropod community at three study sites in Tongkeina, Manado city. The study sites were Bahowo, Batu Meja and Rap-Rap. Data were collected by sampling methods using quadratic transect technique. The study was conducted from November to December 2012. Over all, 20 species of gastropods comprising 7 families in 4 orders were collected. Among all sites, the highest density of 35,64 individuals/m2 was found in Bahowo site and the lowest density of 14,84 individuals/m2 was found in Rap-Rap site. The highest relative density was found at Batu Meja site, shown by Columbella versicolor species with relative density of 55.9%. Diversity index ranged from 1,4786 (Batu Meja) – 1,9382 (Rap-Rap). Batu Meja site shown an index value of C = 0,35 which indicating that there is dominance by 2 species, i.e.Columbella vesicolor and Columbella rusticoides, in that site.Associations between gastropod species at all three locations formed either positive or zero association, whereas negative associations between gastropod populations were not found. Keywords : community structure, gastropods, seagrass, Tongkeina, Manado  ABSTRAK Komunitas gastropoda merupakan salah satu komponen penting dalam rantai makanan di padang lamun.  Tujuan penelitian ini adalah mengidentifikasi jenis gastropoda dan mengetahui kepadatan populasi, kepadatan relative populasi, keanekaragaman spesies, dominasi dan asosiasi antar spesies gastropoda yang telah dilakukan pada tiga lokasi penelitian di kelurahan Tongkeina kota Manado. Pengambilan data dilakukan dengan metoda sampling yang menggunakan teknik transek kuadrat. Waktu penelitian pada bulan November sampai Desember 2012.  Berdasarkan hasil penelitian, diperoleh 20 spesies gastropoda yang terdiri dari 7 famili dalam 4 ordo. Kepadatan tertinggi dari semua stasiun adalah Stasiun Bahowo yakni 35,64 ind/m2, Stasiun Rap-Rap adalah stasiun yang memiliki kepadatan terendah dari ketiga stasiun penelitian yakni 14,84 ind/m2. Kepadatan relative tertinggi terdapat di Stasiun 1 (Batu Meja) yaitu pada spesies Columbella versicolor dengan kepadatan relatif  55,9 %. Indeks keanekaragaman berkisar 1,4786 (Batu Meja)–1,9382 (Rap-Rap). Stasiun Batu Meja dengan nilai indeks C=0,35 menunjukan 2 spesies yang mendominasi yakni Columbella vesicolor dan Columbella rusticoides. Asosiasi antara spesies gastropoda di ketiga lokasi membentuk asosiasi positif dan asosiasi nol, sedangkan asosiasi negative antara populasi gastropoda tidak ditemukan. Kata kunci : struktur komunitas, gastropoda, lamun, Tongkeina, Manado

scholarly journals THE ESTIMATION METHODS OF MICROFILLERS INFLUENCE ON CEMENT STONE PROPERTIES/MIKROUŽPILDŲ ĮTAKOS CEMENTINIO AKMENS SAVYBĖMS ANALITINIO ĮVERTINIMO PRINCIPAI

1997 ◽  
Vol 3 (10) ◽  
pp. 69-75
Author(s):  
Juozas Deltuva ◽  
Žymantas Rudžionis
Keyword(s):  
Relative Density ◽  
Silica Fume ◽  
Cement Paste ◽  
Heterogeneous Material ◽  
Estimation Methods ◽  
Cement Stone ◽  
Structural Element ◽  
Regular Form ◽  
Amorphous Sio2 ◽  
Hardening Process

The concrete and cement microfillers are materials of different fineness, such as wastes of production or pulverized rocks. According to their influence on cement hardening process, they may be classified into inert microfillers or chemically active ones. The chemically active microfillers, such as silica fume, fly ashes and others, have more then 50% amorphous SiO2, that takes part in cement hardening process. Inert microfillers, such as granite, dolomite, sand dust and others, in most cases have no influence on the cement hydration. The usage of microfillers in concrete is common, but so far no clear dependence between the quantity of added microfillers and properties of concrete has been established. One of possible ways to estimate the microfillers influence on the products with cement binder is the structural element method. The structural element is the smallest cell, approximated to a spatial figure of regular form, that has all components with the same proportions, as in all the volume of heterogeneous material. The essence of this method is to divide the mix in to bigger particles, that are named “nuclei” of structural elements and take 50% of all mix volume, and smaller particles, that form cover layers of the nuclei and make up the rest of the volume of the mix. The dependence between the relative density of loose materials and relation (1) between the diameters of the bigger and smaller particles of the structural element has been estimated. This relation is changed when microfillers are added to the cement. There is a possibility to optimize relative density by (2), (3) and (4) relations, if the granulometric composition of the cement and microfillier is known. The experimental and calculated results of this optimization are shown in Table 1. The properties of pressed cement stone with inert microfillers admixture are presented in Table 2. Formulae for calculating the relative density (8) and compressive strength (11) of hardening cement have been estimated. The chemically active microfillers, such as silica fume, interact with Ca(OH)2 and form new CSH. The density and strength of cement stone increased after this interaction. The influence of chemically active microfillers on the relative density of the cement stone is given in (12). The density of cement stone increases to 4.5% and strength increases to 40.2%, if the quantity of inert microfillers in the cement paste reaches 10%. The density of cement stone increases to 7.4% and strength increases to 54.7%, if the quantity of chemically active microfillers in the cement paste reaches 10%.

scholarly journals Effects of disturbance by plateau pika on the β diversity of an alpine meadow

2021 ◽  
Vol 45 (5) ◽  
pp. 476-486
Author(s):  
Jie LI ◽  
Ying-Ying CHEN ◽  
Fu-Yun QIAO ◽  
Di-Gang ZHI ◽  
Zheng-Gang GUO ◽  
...  
Keyword(s):  
Alpine Meadow ◽  
Plateau Pika

scholarly journals Human impact and population dynamics in the Neolithic and Bronze Age: Multi-proxy evidence from north-western Central Europe

The Holocene ◽  
2019 ◽  
Vol 29 (10) ◽  
pp. 1596-1606 ◽  
Author(s):  
Ingo Feeser ◽  
Walter Dörfler ◽  
Jutta Kneisel ◽  
Martin Hinz ◽  
Stefan Dreibrodt
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Bronze Age ◽  
Human Impact ◽  
Central Europe ◽  
Human Activity ◽  
Temporal Distribution ◽  
Relative Population ◽  
Erosion History ◽  
North Western

This paper aims at reconstructing the population dynamics during the Neolithic and Bronze Age, c. 4500–500 cal. BC, in north-western Central Europe. The approach is based on the assumption that increased population density is positively linked with human activity and human impact on the environment, respectively. Therefore, we use archaeological 14C dates and palaeoenvironmental data from northern Germany and south-western Denmark to construct and compare independent proxies of human activity. The latter involves relative quantification of human impact based on pollen analysis and soil erosion history inferred from summarizing of dated colluvial layers. Concurring patterns of changes in human activity are frequently recorded on a multi-centennial scale. Whereas such multi-proxy patterns are interpreted to indicate relative population changes, divergent patterns are discussed in the context of proxy-related uncertainties and potential biases. Patterns of temporal distribution of increasing and decreasing human activity are understood as ‘boom and bust’ phases in population density/size. Based on the comparison of the three proxies, we identify five phases of growing (boom) and four phases of decreasing (bust) population. The boom phases date to ca. 4000–3500, 3000–2900, 2200–2100, 1450–1300 and 1000–750 cal. BC. The bust phases to ca. 3200–3000, 2400–2300, 1650–1500 and 1200–1100 cal. BC.

Nature and Number of Ground-Beef Microorganisms Capable of Growth at 25°C but Not at 32°C1

1988 ◽  
Vol 51 (3) ◽  
pp. 176-180 ◽  
Author(s):  
E. G. STEINBRUEGGE ◽  
R. BURT MAXCY
Keyword(s):  
Population Density ◽  
Ground Beef ◽  
Relative Population ◽  
Higher Temperature

The nature and relative population density of microorganisms capable of growth at 25°C but not at 32°C was determined on enumerations from ground beef. Only approximately 60% as many bacteria were recovered when incubation was at the higher temperature. One-third of the randomly selected isolates from the 25°C plates were unable to grow at 32°C. Some of these isolates were strikingly similar to pathogens. Incubation of plates at 25°C for 48 h is recommended to improve recovery of bacteria of significance in ground beef.

scholarly journals Bounds on Absolute Gypsy Moth (Lymantria dispar dispar) (Lepidoptera: Erebidae) Population Density as Derived from Counts in Single Milk Carton Traps

Insects ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 673
Author(s):  
Ksenia S. Onufrieva ◽  
Alexey V. Onufriev ◽  
Andrea D. Hickman ◽  
James R. Miller
Keyword(s):  
Population Density ◽  
Gypsy Moth ◽  
Management Strategies ◽  
Dispersal Distance ◽  
Upper And Lower Bounds ◽  
United States Department ◽  
Department Of Agriculture ◽  
Moth Male ◽  
Monitoring Traps ◽  
Absolute Population

Estimates of absolute pest population density are critical to pest management programs but have been difficult to obtain from capture numbers in pheromone-baited monitoring traps. In this paper, we establish a novel predictive relationship for a probability (spTfer(r)) of catching a male located at a distance r from the trap with a plume reach D. spTferr=spTfer01+rD2, r≤Rmax0, r>Rmax, where spTfer(0) is the probability of catching an insect located next to the trap and Rmax is the maximum dispersal distance for the insect during the trapping period. The maximum dispersal distance for gypsy moth is known to be 1600 m. The probability of catching a gypsy moth male located next to a United States Department of Agriculture (USDA) milk carton pheromone-baited trap is 0.37, the overall probability of catching a male from the entire trapping area (Tfer) of ~800 ha is 0.0008, and plume reach of this trap is D = 26 ± 3 m. The equation for spTfer(r) is used to derive statistical upper and lower bounds (95% confidence interval) on the population density for the given value of a single trap catch. This combination of trap parameters appears to produce an effective trap: even a catch of 1 male provides meaningful lower and upper bounds on absolute population density. Applications in the management programs are discussed, and a look-up table is provided to translate the catches in USDA milk carton pheromone-baited traps to absolute population bounds, which can help design better management strategies.

The effect of plant density on populations of the cabbage root fly (Erioischia brassicae (Bch.)) and the cabbage stem weevil (Ceutorhynchus quadridens (Panz.)) on cauliflowers

1976 ◽  
Vol 66 (1) ◽  
pp. 113-123 ◽  
Author(s):  
S. Finch ◽  
G. Skinner
Keyword(s):  
Plant Density ◽  
Unit Area ◽  
Individual Plant ◽  
Cabbage Root Fly ◽  
Plant Densities ◽  
Equivalent Area ◽  
Concentric Circles ◽  
The Absolute ◽  
Absolute Population

AbstractTo study the effects of plant density on populations of the cabbage root fly (Erioischia brassicae (Bch.) ) and the cabbage stem weevil (Ceutorhynchus quadridens (Panz.)), cauliflowers were planted in 24 concentric circles to achieve spacings of 10–90 cm at 22 plant densities (1·5–83/m2). Some plants were treated with a root drench of chlorfenvinphos. Each week female cabbage root flies laid approximately three times as many eggs per individual plant at the lowest than at the highest plant densities tested. This was equivalent to approximately 350 and 5000 eggs/m2, respectively. The numbers of cabbage root fly pupae produced ranged from 11/m2 at the lowest to 210/m2 at the highest plant density. In the absence of an insecticide, increasing the plant density considerably increased the absolute population of the pest without affecting cauliflower yield. Approximately seven times as many flies were produced per unit area of untreated mini-cauliflowers as from an equivalent area of plants growing at a conventional density. When chlorfenvinphos was not applied, damage by the cabbage stem weevil occurred in 30% and 70% of the plants grown at the lowest and highest densities, respectively.

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