21 research outputs found
Invasive potential of the Peruvian pepper tree (Schinus molle) in South Africa
Thesis (PhD (Conservation Ecology and Entomology))--University of Stellenbosch, 2009.ENGLISH ABSTRACT: Natural and semi-natural ecosystems and human communities worldwide are under siege
from a growing number of destructive invasive alien species. Alien species are those
whose presence in an area is due to intentional or accidental introduction as a result of
human activities. Some alien species become invasive, and some cause tremendous
destruction to the ecosystem and their stability, but we do not yet understand fully the
many factors that determine the levels of invasiveness in alien species. However,
management of alien plants requires a detailed understanding of the factors that make
them invasive in their new habitat. The aim of this study was to explore in detail the
processes and potential for invasion of Schinus molle (Peruvian pepper tree) into semiarid
savanna in South Africa and to examine the potential for this species to invade
further in these ecosystems, and in other South African biomes.
In this thesis I explored the patterns and processes of invasion of S. molle in semiarid
savanna using small-scale experiments to investigate physical and ecological barriers
to invasion that prevent or accelerate the invasion of this species. I examined factors such
as pollination; seed production; seed dispersal; seed predation and viability, all known to
contribute to invasiveness. I highlighted the critical role of microsite conditions
(temperature, humidity, water availability) in facilitating S. molle seedling establishment
in semi-arid savanna and demonstrated that microsite type characteristics need to be
considered for management and monitoring of the species in South Africa. I
demonstrated the ability of S. molle to out-compete indigenous woody plants for light and
other resources and also showed that disturbance of natural ecosystems was not a
prerequisite for invasion, although human activities such as tree planting have played a
major role in disseminating this species in South Africa.
Predicting the future distribution of invasive species is very important for the
management and conservation of natural ecosystems, and for the development of policy.
For this reason, I also assessed the present and potential future spatial distribution of S.
molle in South Africa by using bioclimatic models and a simulation-based spread model.
I produced accurate profiles of environmental conditions (both biophysical and those related to human activities) that characterize the planted and naturalized ranges of this
species in South Africa, by linking species determinants, potential habitat suitability and
likely spread dynamics under different scenarios of management and climate change. All
those components provided insights on the dynamics of invasions by fleshy-fruited
woody alien plants in general, and on S. molle invasions in South Africa in particular. I
developed a conceptual model that described S. molle population dynamics leading to an
understanding of the processes leading to the invasive spread of this species in South
Africa. This work also emphasized the need for policy review concerning the invasive
status of S. molle in South Africa, and recommendations are made for future research.AFRIKAANSE OPSOMMING: Die natuurlike and half-natuurlike ekosisteme sowel as menslike gemeenskappe
wereldwyd word bedreig deur ‘n groeiende hoeveelheid indringerplantspesies.
Indringerplantspesies (daardie spesies wie se teenwoordigheid toegeskryf kan word aan
opsetlike of toevallige inbringing deur menslike toedoen) is ‘n bedreiging nie net vanweë
die massiewe verwoesting van die ekosisteme en ekosisteemstabilitiet nie, maar ook
omdat ons nog nie ten volle verstaan hoe hulle van skaars in hul natuurlike omgewing tot
dominant in hul nuwe habitat gaan nie. Bestuur van indringer plante vereis ’n begrip van
biologise en ekologiese faktore wat lei tot hulle indringing in die nuwe habitat. Die
primêre doel van hierdie studie was om in detail uit te vind wat die prosessesse en
potensiaal is vir die indringing van S. molle (die Peruviaanse peper boom) in droë
savanna en om indringingspatrone in droë savanna met huidige en potensieële
toekomstige patrone in ander Suid-Afrikaanse biome te vergelyk.
In hierdie tesis ondersoek ek die patrone en prosesse wat verband hou met die
indringing van S. molle in droë savanna deur gebruik te maak van kleinskaalse
eksperimente om fisiese en ekologise hindenisse te ondersoek wat indringing van S. molle
in Suid-Afrika voorkom of versnel. Dit sluit faktore in wat bekend is om by te dra tot
indringing van plant spesies, soos bestuiwing, saadproduksie, saadpredasie en
kiemkragtigheid. Ek het die kritieke rol beklemtoon van mikroomgewingskondisies
(temperatuur, humiditeit, waterbeskikbaarheid) in die fasilitering van S. molle
saailingvestiging in droë savanna en het gedemonstreer dat die tipe
mikroomgewingskarakteristieke in ag geneem moet word by betuur en monitering van
die verspreiding van S. molle in Suid-Afrika. Ek het die vermoë van S. molle om
inheemse plante te uitkompeteer gedemonstreer, en het gewys dat versteuring van
natuurlike ekosisteme nie ’n voorvereiste vir S. molle indringing was nie, hoewel
menslike aktiwiteite soos boomaanplantings ’n groot rol speel deur by te dra tot
indringing van hierdie spesie in Suid-Afrika. Voorspelling van toekomstige verspreiding van indringerspesies is baie belangrik
vir die bestuur en bewaring van natuurlike ekosisteme, sowel as vir ontwikkeling van
wetgewing. Daarom is die huidige en potensiele toekomstige ruimtelike verspreiding van
S. molle in Suid-Afrika bereken deur inkorporering van bioklimaatsmodelle en simulering
gebasseer op ’n verspreidingsmodel. Ek het derhalwe akkurate profiele van
omgewingstoestande (beide fisiese en daardie wat verband hou met menslike aktiwiteite)
wat die aangeplante en natuurlike omvang van die spesie in Suid-Afrika kenmerk
geproduseer deur spesiedeterminante, potensieële geskiktheid van habitatte en moontlike
verspeidingsdinamika onder verskillende bestuursscenarios en kimaatsverandering te
koppel. Al hierdie komponente verskaf insig in die dinamika van die indringing van
houtagtige plante met vlesige vrugte oor die algemeen en S. molle in besonder in Suid-
Afrika. Hierdie werk beklemtoon ook die behoefte vir hersiening van beleidsrigtings wat
betrekking het op die indringerstatus van S. molle in Suid-Afrika en maak aanbevelings vir toekomstige navorsing
The contribution of NTFPs gathering: To rural people's livelihoods around two timber concessions in Gabon
NTFP are often presented as bringing a major contribution to rural livelihoods in terms of food and cash, and this particularly for rural communities. Few data are available in Gabon to confirm this common assertion. An annual monitoring of 127 households was conducted in 14 villages around two timber concessions in the south-east and south-west regions of Gabon. Conventional socio‐economic survey tools such as focus group discussions, census and semi-structured interviews of households were used in gathering data during one year. Results reveal that rural people depend on various sources of livelihoods for food and income generation, but overall, the current contributions of vegetal NTFPs are insignificant compared to other activities. Odika (Irvingiagabonensis), atanga sauvage (Dacryodes buettneri), fungus (Termitomyces spp) and “nut” (Coula edulis) represent the main forest products that are commonly harvested by rural people, primarily for subsistence purposes while the surplus is sold. Although some efforts were made to promote the NTFP sector in the country, the results of this study suggest that: (1) the main components of the decree No.137/PR/MEFP of February 4, 2009, that prohibited the logging of five multiple use tree species over a period of 25 years should be reconsidered for revision; (2) the State authorities and partners should promote projects aiming at increasing the knowledge of the NTFP sector. These projects should contribute to the census of NTFP (for food, medicine and services), characterize their uses, the market chains of target products, and the development potential of NTFP. Such projects may help Gabon and other Congo Basin countries to fix norms/standards for a sustainable natural resource management and for enhancing their contribution to the national economy. This will be particularly relevant in the light of dwindling oil revenues and the need to diversify and promote other revenue sources in the country. (Résumé d'auteur
Identification et caractérisation de la dynamique de la grande faune dans le baï de Momba (nord-est Gabon)
Les baïs sont des clairières marécageuses localisées généralement au coeur des forêts du Bassin du Congo. Ce sont des écosystèmes particulièrement riches en espèces animales et végétales. Si les connaissances portant sur l’origine de ces milieux sont bien documentées, les espèces de la faune sauvage (éléphants, buffles, sitatungas, etc.) colonisant ces écosystèmes demeurent encore mal connues. Par ailleurs, les informations qui existent sur ces espèces fauniques restent fragmentaires. C’est pour ces raisons qu’une étude basée sur les méthodes d’observation de la faune (scan sampling et animal focal) a été conduite dans le baï de Momba durant 33 jours. Ce travail visait l’identification de la macrofaune présente dans ce type de milieux et l’analyse de la dynamique de cette faune. Au total, 969 animaux ont été observés. Ces animaux ont été représentés majoritairement par les sitatungas (Tragelaphus spekei), les éléphants (Loxodonta africana cyclotis), les buffles (Syncerus caffer nanus) et les colobes (Colobus guereza). En termes de fréquence d’observation, les sitatungas (27%) ont été le groupe le plus abondant, suivis par les éléphants (8%) et les buffles (7%). Les autres animaux ont été faiblement observés avec une fréquence de moins de 2%. La fréquentation du baï de Momba par ces espèces témoigne du rôle crucial que pourrait jouer les zones humides dans la gestion durable de la biodiversité dans le Bassin du Congo. Aussi, il apparaît nécessaire que des mesures de protection et de suivi de la dynamique de ces peuplements soient rapidement entreprises afin de protéger la biodiversité faunique de cemilieu.Mots clés : Loxodonta africana cyclotis, Syncerus caffer nanus, Tragelaphus spekei,Colobus guereza, baï de Momba, Gabon
WILDMEAT interventions database: A new database of interventions addressing unsustainable wild meat hunting, consumption and trade
First paragraph: Wild meat has long been used as a source of food and income by many communities across the tropics (Ingram et al., 2021). Recently, however, growing human populations and increasing commercial trade to urban markets have driven up demand and prices for wild meat products and led to unsustainable levels of wildlife harvesting in many places (Coad et al., 2019). Overexploitation of wildlife has been linked to significantly reduced wildlife populations (Benítez-López et al., 2017) and increased extinction risk for many medium and large-bodied species (Dirzo et al., 2014). The loss of these species poses food and income security risks for those dependent on wild meat for livelihoods (Ingram, 2020), disproportionately impacting the poorest households whose reliance on the resource is greatest (Nielsen et al., 2018). Despite the clear need to manage unsustainable wild meat harvesting to protect wildlife and the ecosystems they live in, management is poor in many areas, and in others, absent (Ingram et al., 2021; Wicander & Coad, 2018).Output Status: Forthcoming/Available Onlin
Wild meat Is still on the menu: Progress in wild meat research, policy, and practice from 2002 to 2020
Several hundred species are hunted for wild meat in the tropics, supporting the diets, customs, and livelihoods of millions of people. However, unsustainable hunting is one of the most urgent threats to wildlife and ecosystems worldwide and has serious ramifications for people whose subsistence and income are tied to wild meat. Over the past 18 years, although research efforts have increased, scientific knowledge has largely not translated into action. One major barrier to progress has been insufficient monitoring and evaluation, meaning that the effectiveness of interventions cannot be ascertained. Emerging issues include the difficulty of designing regulatory frameworks that disentangle the different purposes of hunting, the large scale of urban consumption, and the implications of wild meat consumption for human health. To address these intractable challenges, we propose eight new recommendations for research and action for sustainable wild meat use, which would support the achievement of the United Nations Sustainable Development Goals. Expected final online publication date for the Annual Review of Environment and Resources, Volume 46 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates
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COVID-19, systemic crisis, and possible implications for the wild meat trade in sub-Saharan Africa
Wild animals play an integral and complex role in the economies and ecologies of many
countries across the globe, including those of West and Central Africa, the focus of this
policy perspective. The trade in wild meat, and its role in diets, have been brought into
focus as a consequence of discussions over the origins of COVID-19. As a result, there
have been calls for the closure of China’s “wet markets”; greater scrutiny of the wildlife
trade in general; and a spotlight has been placed on the potential risks posed by growing human populations and shrinking natural habitats for animal to human transmission of
zoonotic diseases. However, to date there has been little attention given to what the consequences of the COVID-19 economic shock may be for the wildlife trade; the people who
rely on it for their livelihoods; and the wildlife that is exploited. In this policy perspective,
we argue that the links between the COVID-19 pandemic, rural livelihoods and wildlife
are likely to be more complex, more nuanced, and more far-reaching, than is represented in
the literature to date. We develop a causal model that tracks the likely implications for the
wild meat trade of the systemic crisis triggered by COVID-19. We focus on the resulting
economic shockwave, as manifested in the collapse in global demand for commodities such
as oil, and international tourism services, and what this may mean for local African economies and livelihoods. We trace the shockwave through to the consequences for the use
of, and demand for, wild meats as households respond to these changes. We suggest that
understanding and predicting the complex dynamics of wild meat use requires increased
collaboration between environmental and resource economics and the ecological and conservation sciences
Renosterveld restoration : the role of competition, herbivory and other disturbances
Thesis (MSc)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: West Coast Renosterveld is one of the most threatened vegetation types in South
Africa. Less than 5% of the original extent of this vegetation type remains, of which
80% is on private land. In addition to fragmentation, much of the vegetation has been
ploughed for crop production and then abandoned and invaded by alien plants.
Restoration of transformed areas may improve the conservation status of this
vegetation type. Indigenous species do not return to abandoned agricultural fields for
decades even if these are adjacent to natural areas since their return is limited either
by seed dispersal or seedling establishment. The aim of this study was to examine
the recovery of indigenous vegetation on abandoned fields.
Renosterveld, as we know it today, is an asteraceous shrubland, dominated mainly
by renosterbos (Eytropappus rhinocerotis), but might have been a grassland or a
grassland-shrubland mosaic. Historical records indicate that species of large game
were common in the Western Cape when the early settlers arrived, but most of these
have since disappeared. It is thus impossible to reconstruct exactly the ecological
processes and functioning of Renosterveld.
The first part of the study was designed to examine the effects of grass competition,
grazing by indigenous large herbivores, and interaction of these two factors on the
establishment, growth and survival of transplanted Renosterveld seedlings on an
abandoned agricultural field. Experimental transplanting of indigenous shrubs into an
old field showed that most of the plants investigated competed for resources with
lawn grasses on the field, and competition affected the seedlings throughout the
experiment. Mortality was higher, and growth was reduced for seedlings exposed to
grass competition. With the exception of wild olive (Olea europaea spp.africana),
herbivory alone had no significant impact on the target species. Herbivory was at a
low intensity (20 ha/large animal unit); higher grazing pressures might have given
different results. No interaction between competition and herbivory was found for the
species investigated; competition and grazing therefore seem to influence the
seedlings independently. The second part of this study was conducted to examine the effects of different
management strategies, viz: brush cutting, burning and herbicide application on plant
species recruitment and community composition and to ascertain their applicability
by farmers for large scale restoration of Renosterveld. My comparison of the different
strategies for controlling annual alien grasses indicated that these did not differ
significantly in their effects on species richness. Burning reduced shrub cover and
increased overall species richness and diversity. Burning also reduced grass
biomass, and increased recruitment of indigenous seedlings. The use of herbicide
resolved the problem of grass biomass invasion and increased shrub species
richness. The herbicide application did not appear to have long-term negative effects
on the soil quality. Brush cutting did not remove grass biomass on the old field.
Experimental re-seeding with an indigenous grass and shrub species into treated
plots resulted in low recruitment.
My conclusion is that grass can reduce recruitment and growth of many indigenous
shrub species. My recommendation for the restoration of old fields in West Coast
Renosterveld is to apply herbicide to remove grass competition, and then, after the
herbicide has degraded, to oversow the field with seeds of indigenous shrub and
grass species of early successional stages to increase overall species diversity.AFRIKAANSE OPSOMMING: Weskus Renosterveld is een van die mees bedreigde plantegroei soorte in Suid
Afrika. Minder as 5% van die oorspronklike omvang van hierdie plantegroei tipe is
oor, en dit hoofsaaklik (80%) op privaatlande. Saam met fragmentasie, is baie
Renosterveld areas ook omgeploeg vir boerdery en dan net so gelos, met die gevolg
dat uitheemse plante hierdie areas ingedring het. Restorasie of herstelling van sulke
bewerkte lande kan dalk die bewaringsstatus van hierdie plantegroei tipe verbeter.
Natuurlike vestiging van Renosterveld spesies op sulke ou bewerkte lande gebeur
nie, selfs al is daar Renosterveld direk langs so ‘n ou veld. Die hervestiging van
inheemse spesies is dus tot saadverspreiding or saailingbevestiging beperk. Die
doel van hierdie studie is om die stadige terugkoms van inheemse plantegroei na
verlate bewerkte velde te verduidelik.
Renosterveld is ‘n struikveld waarin die renosterbos (Eytropappus rhinocerotis)
domineer, maar kan ook ‘n grasveld of ‘n grasveld-struikland mengsel wees. Groot
herbivore was algemeen in die Wes Kaap toe die eerste settelaars gearriveer het,
maar intussen het omtrent al die groot wild spesies verdwyn. Dit is dus ontmoontlik
om die ekologiese prosesse en funksionering van Renosterveld presies so te herstel.
Die eerste deel van hierdie studie bestudeer die effek van graskompetisie, weiding
deur inheemse groot herbivore, en die interaksie tussen hierdie twee faktore op die
vestiging, groei en oorlewing van oorgeplante Renosterveld saailinge in ‘n verlate ou
veld. Die eksperimentele oorplanting van inheemse struike in ‘n ou land het gewys
dat die meeste van hierdie plante kompeteer vir hulpbronne met kweekgras wat op
die ou veld groei. Kompetisie het die saailinge deur die hele eksperiment
geaffekteer. ‘n Hoër mortaliteit en verminderede groei in saailinge wat aan gras
kompetisie blootgestel was, is waargeneem. Met die uitsondering van Olea
europaea spp. africana, het herbivorie alleen geen betekenisvolle impak op plant
spesies gehad nie. Weidingsdruk was laag (20 ha/groot vee eenheid); ‘n groter
weidingsdruk sou miskien ‘n ander uitkoms gehad het. Geen interaksie tussen
kompetisie en herbivorie is waargeneem in die bestudeerde plantspesies nie. Dit wil dus voorkom of kompetisie en weiding die saailinge onafhanklik van mekaar
beïnvloed.
Die tweede deel van hierdie studie was onderneem om die effek van verskillende
behandelings (kontrole, sny, brand en herbisied toediening) op plantspesie vestiging
en samestelling te bestudeer asook om bestuurmetodes te toets was deur boere op
groot skaal gebruik kan word om Renosterveld te herstel. In ‘n vergelyking van
verskillende bestuur metodes (kontrole, besnoeiing, brand en herbisied) om
eenjarige uitheemse gras te beheer, is gewys dat die behandlings nie betekenisvol
van mekaar verskil in hulle effek op spesierykheid nie. Vuur het struikbedekking
verminder en totale spesies rykheid en diversitiet verhoog. Die gebruik van ‘n
herbisied het die probleem van grasindringing opgelos en het ook
struikspesiesrykheid verhoog. Die herbisied het nie lang termyn negatiewe effekte op
grond kwaliteit gehad nie. Sny het nie gras biomassa verlaag op die ou land nie.
Eksperimentele plant van inheemse grasse en struike in die behandelde areas, het
lae vestiging tot gevolg gehad.
My algemene afleiding is dus dat gras die hervestinging en groei van baie inheemse
struikspesies verminder. Ek stel voor dat herbisied gebruik moet word om gras
kompetisie te verminder. Nadat herbisied residue in die grond afgebreek is, moet
die ou land met inheemse struik en grasspesies, wat in vroeë suksessie stadiums is,
beplant word om sodoende totale spesiediversiteit te verhoog en uiteindelik ou
bewerkte lande in Weskus Renosterveld te herstel
Changes in livelihood practices, strategies and dependence on bushmeat in two provinces in Gabon
Traditional, forest resource-dependent livelihoods face multiple challenges. In Gabon, bushmeat provides food and income for rural communities. This study investigates how villagers believe livelihood practices and dependence on bushmeat changed over the last decade and if alternative income and food generating strategies can be sustainable. Our results show that remote villages near Moukalaba Doudou National Park hardly changed practices. Less remote villages near Tchibanga experienced declining hunting revenues and are switching to alternatives. Villages near Libreville almost completely changed strategies, and are no longer dependent on forest resources. Changes in livelihood practices were driven either by resource depletion or urbanization. The ability to change depended on proximity to facilities and infrastructure. Although most respondents were able to change, not all alternative strategies are sustainable. The results highlight the need to evaluate the long-term effectiveness of alternative poverty reduction and nature conservation strategies in a context of urbanization and food security. There is a need to reduce bushmeat demand, making supply more sustainable through effective resource governance and creating a conducive institutional and policy environment