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Diversity and production in an Afromontane Forest
Full text linkBackground
This contribution evaluates the effect of forest structure and tree species diversity on plot productivity and individual tree growth in the unique Knysna forests in Southern Africa using mapped tree data from an observational study that has been re-measured over a period of 40 years.
Methods
The effects of tree species diversity and forest structure on tree growth and forest production are evaluated on three levels of resolution: a) the forest community (canopy, sub-canopy species), b) the subplots (number of trees per ha, skewness of the diameter distribution, diameter coefficient of variation) and c) the immediate neighborhood of selected reference trees (“Mingling”, “Dominance”, Aggregation” and “Size Variation”).
Results
An analysis of the community level identified two distinct clusters, one including dominant/canopy species with the highest growth rates and a greater variation of growth, and another cluster which includes the remaining subcanopy species which have a smaller maximum size and lower rates of growth. The area-based structure variables on plot level have a highly significant effect on total basal area growth. However, the effects of forest density and species richness on productivity were not straight forward. Maximum basal area production of about 0.75 m2/ha/year is achieved at medium levels of richness (around 20 species per ha) and medium levels of density (around 30 m2/ha basal area) using percentile regression estimates. The relative “Dominance” of a selected reference tree had a highly significant effect on individual tree growth on all investigated species. Other neighbourhood structure variables were only occasionally significant or not significant at all.
Conclusion
This contribution presents a new theoretical framework for analysing natural forests that includes community, plot and neighborhood variables of forest structure and diversity, and a first specific analysis of the structure and dynamics of the Knysna Afromontane Forest, based on a unique set of longterm observations. The species-area (SAR) model developed in this study, represents a new general approach that can be used to derive a common standard of tree species diversity for different plot sizes, the species richness per hectare
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Ecology of the bushpig Potamochoerus porcus Linn. 1758 in the Cape Province, South Africa
Full text linkThesis (PhD) -- Stellenbosch University, 1990.ENGLISH ABSTRACT:Bushpig sociology, energetics, reproduction and population dynamics were
studied over an 8-year period in the Cape Province, South Africa. The
social organization was found to be strikingly different from that known
from other suid species. The basic social unit is a unimaternal family
group, occupying a resource-based territority, with a monogamous mating
system. This form of social organisation is related to the dispersed
nature of food resources, to which it provides exclusive access. It is
reminiscent of canid social systems. Agonistic behaviour, communication
and maternal behaviour were studied as the opportunity arose. The
average home range size was 7,2 kmª, ranging from 3,8 to 10.1 kmª. Home
ranges were often traversed within 1-4 days, as part of territory
patrolling. The average diel ranging distance was 3 km. Bushpig were
active during both night and day and exhibited a basic bimodal rhythm.
The main phase of intensive foraging occurred from before dusk to
midnight, with a secondary activity peak after dawn. Activity schedules
were geared to avoid extreme ambient temperatures. Temperature
regulation and water use were investigated, with particular reference to
thermoregulatory behaviour (nest building). pelage characteristics, body
core temperature dynamics, thermoneutral zones and resting metabolic
rates. The thermoneutral zone for 10 kg bushpig juveniles was estimated
to lie between 13° and 30°C and that for adults between 8° and 25°C.
Foraging behaviour, diet and its nutritient content were investigated.
Regional differences in the nutritional quality of bushpig diets in the
Eastern and Southern Cape were associated with the predominance of
nutrient-rich and nutrient-poor substrates respectively. These in turn
were reflected by divergent life history features in the populations
from the two regions. Patterns of growth and energy storage were
described and the value of various parameters (e.g. mass to size ratio,
fat depositions, blood composition) to evaluate condition was
investigated. In studying reproductive biology, sexual maturation,
female reproductive cycles, prenatal litter statistics, foetal
development, 1actation, breeding seasonality and reproductive turnover
were the main aspects addressed. The role of food quality, body
condition and social status in determining reproductive success was
discussed. Bushpig population density estimates in the Southern Cape
ranged between 0,3 and 0,5 animals/kmª• The dynamics of Southern and
Eastern Cape populations were found to differ. The differences are
consistent with the hypothesis that social organisation is determined by
the distribution and availability of food while diet quality shapes
life history tactics. A life history model was developed which links
edaphoclimatic environmental conditions with diet quality, metabolic
turnover rate and, ultimately, life history features. In the concluding
chapter some of the managerial implications of the research findings are
discussed.AFRIKAANSE OPSOMMING:Die sosiologie, fasette van die energiebalans (temperatuurregulasie,
voeding). voortplanting en bevolkingsdinamika van bosvarke is in die
Kaapprovinsie (Suid-Afrika) oor 'n tydperk van 8 jaar bestudeer. Dit
kon bewys word dat die sosiale organisasie van die bosvark van die van
ander varksoorte verskil. Die basiese sosiale eenheid bestaan uit 'n
familiegroep wat slegs 'n enkele telende moederdier bevat. Ruimtelike
organisasie is gebaseer op 'n stelstel van voedingsterritoriums. 'n
Monogamiese paringstelsel kom voor. Die yl verspreiding van voedsel
word as die onderliggende rede vir die sosiale organisasie beskou.
Gedragspatrone (kommunikasie, aggressie, grootmaak van kleintjies) is
bestudeer soos die geleentheid voorgekom het. Heelwat ooreenkomste is
gevind tussen die sosiale organisasie van die bosvark en lede van die
hondefamilie. Die gemiddelde woongebiedgrootte is 7,2 kmª (tussen 3,8
en 10,1 kmª). Woongebiede word gewoonlik binne 1-4 dae deurkruis en dus
soos territoria gepatroleer. Die gemiddelde daaglike bewegingsafstand
was 3 km. Bosvarke was beide gedurende die nag en die dag aktief en het
'n bimodale aktiwiteitsritme gevolg. Die hoofaktiwiteitsfase van
intensiewe voeding het tussen sononder en middernag plaasgevind, met 'n
sekondere fase na sonop. Soedoende is temperatuuruiterstes vermy.
Temperatuurregulasie en watergebruikpatrone is bestudeer, insluitend
temperatuurreguleringsgedrag, haarkleedeienskappe, liggaamskerntemperature,
termoneutraliteit en metabolise omset. Voedingsgedrag, voedsel en
die voedingswaarde daarvan is ondersoek. Verskille tussen die Oos- en
Suid-Kaap in die kwaliteit van voedsel hang saam met die laer vlak van
voedingsstowwe in die gronde van die Suid-Kaap. Bosvarkbevolkings in
die twee streke toon verskille in populasiedinamika wat hieraan
toegeskryf kan word. Groei- en energiestoorpatrone is beskryf. Die
moontlikhede is ondersoek om kondisie te evalueer met behulp van
parameters soos massa tot grootte-verhoudings, vetneerleggings en
bloedwaardes. Aspekte van voortplantingsbiologie, soos geslagsrypheid,
vroulike voortplantingssiklusse, voorgeboortelike werpselgroottes,
foetale ontwikkeling, laktasie, seisoenaliteit en voortplantingsomset is
behandel. Die rol van voedselkwaliteit, kondisie en sosiale status by
die bepaling van voortplantingsukses word bespreek. Skattings van die
bevolkingsdigtheid van bosvarke in die Suid-Kaap het gewissel tussen 0,3
en 0,5 diere per kmª• Op grond van die verskille in bevolkingsdinamika
tussen bosvarke in die Suid- en Oos-Kaap is 'n model ontwikkel om die
verband tussen bevolkingsregulering en lewensstrategieeë (life history
tactics) te verklaar. Hiervolgens het voedselbeskikbaarheid die tipe
sosiale organisasie bepaal terwyl die lewensstrategieë van bevolkings
die gevolg is van voedselkwaliteit. Die model stel vaar 'n verband
tussen groeipleksomstandighede, voedselkwaliteit, metaboliese omset en
bevolkingsdinamika. In die laaste hoofstuk word sommige van die
bestuursimplikasies van die navorsingsbevindinge bespreek.Doctora
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Age assessment of the bushpig Potamochoerus porcus Linn. 1758 in the southern Cape
Full text linkThesis (MSc)--Stellenbosch University, 1983.Some pages appear scribbled on due to condition of original copy.Some page numbers may not be visible or appear cut off due to condition of original copy.ENGLISH ABSTRACT:
The bushpig (Potamochoerus 2)orcus) is one of the least
studied of the larger African mammals. This contrast to the other two African auids, the is in striking warthog (Phacochoerus aethiopicus) and giant forest hog (Hylochoerus meinertzhgeni), which have been subjected to detailed studies i.a. by Cumming (1970), D'Huart (1978) and Mason (1982).
Because the bushpig is a prominent species both in the
forest biome and on adjacent agricultural land, autecological
research on the species is presently being undertaken to provide information needed for multipurpose forest management. This study on age determination is part of the broader research programme on the species.Master
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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