Thesis (MSc)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: The composition and state of soil-stored seed banks on- and off the mesa Tafelberg, in the Nama Karoo rangelands of the Eastem Cape, South Africa, were investigated within the context of a broader restoration ecology project "Restoration of degraded Nama Karoo rangelands: the role of conservation islands'". The premise for this seed bank study was that restoration of degraded semi-arid rangelands is possible through applied management programs based on the methodology and practice of ecological restoration. Broadly acknowledged properties of non-equilibrium environments (e.g. unpredictable climates and varying degrees of disturbance) and soilstored seed banks (e.g. spatial and temporal distributions) formed the basis for investigating. the general environment and the properties.. of existing seed, banks, in the Tafelberg locality. The potential role of hills as refugia for palatable plant species was an under-lying element of the investigation. Following a brief investigation, of historical and contemporary research and policy on rangeland degradation in semi-arid regions of the world, the fundamental need for comprehensive and applied seed bank research in the Nama Karoo is emphasised. Within the framework of the umbrella project, the seed bank study examined local environmental criteria commencing with an investigation into seed bank- and vegetation habitats. Chemical and physical properties of soils from twenty two sites on- and off Tafelberg were described. Substantial soil habitat variation, between the top, the north west slopes and plains and the south east slopes and plains of Tafelberg, was identified. Micro-site variation between open-canopy (interplant spaces) and closed-canopy (under plant cover) microhabitats was found to be significant Primary soil habitat differences were linked to soil organic matter content which was found to be low on the plains relative to the top and slopes; and, low in open-canopy micro-sites relative to closed-canopy sites. Soil texture and nutrient composition on- and off Tafelberg was found to be highly variable with significant differences between the top and the plains as well as between the north west and south east plains. The slopes were found to be intermediate (showing some level of gradient) between the top and the plains. Soil nutrient variation was interpreted as a function of textural and parent-material properties of soils. Anthropogenic factors for accelerated erosion, deposition, leaching and salt-crust formation were also considered. It was concluded that while properties of soils on- and off Tafelberg are inherently related to parent soils, changes to textural and nutrient properties may be occurring and these changes may have been exacerbated by high levels of grazing. An investigation (focusing on small shrubs) of plant phenological response, in relation to rainfall and grazing gradients, identified trends of peak budding- and flowering seasons following rainfall during summer and autumn respectively. A continuum of seeding activity, with peaks in late autumn and early winter, was construed from quarterly data. Flush vegetative growth was noted for most small shrubs during spring, autumn and summer surveys. Since some form of activity related to reproductive output (flush growth, budding, flowering or seeding) was apparent at almost all times of the year, it is argued that high intensity disturbance (including grazing) might impact negatively on plant survival, leading to reduced reproductive input (i.e. seeds) into future generations. Plant communities on the top and plains are described noting significant differences between vegetation on top of Tafelberg (comprising primarily high production, palatable grass and shrub species) and that on the plains (comprising mainly spinescent, ephemeral, toxic and low production species). Given the high grazing pressure on the plains (relative to the less utilised slopes and top of Tafelberg), differences in vegetation composition are discussed in relation to studies elsewhere that describe degraded rangelands. It is concluded firstly that the plains surrounding Tafelberg are degraded, secondty that long term over-utilisation has altered vegetation composition and finally that inter-grazing rest periods of three- or six months alone may not restore vegetation diversity nor desirable plant species to the plains. Results of germination trials (investigating soil-stored seed banks) from two sampling episodes (spring and autumn 1998) revealed that seed banks in soils removed from the plains, slopes and top of Tafelberg followed distribution patterns observed in above-ground vegetation. Species-specific data was not finalised for this thesis since not all seedlings matured and flowered within given time constraints. In order to compare seedling emergence data, plant categories were developed that distinguished ephemerals versus persistent (perennial) species and dicotyledonous species versus grasses and other monocotyledonous plants. Samples from the top and the middle to upper slopes showed a high percentage of palatable and persistent grass and shrub species present in soil-stored seed banks while over twothirds of plants germinating from plains' soil samples were ephemeral species and most of these were both tiny «Scm) and short-lived «3 months). Most of the perennial species germinating from plains' samples were seedlings of Pentzia incana, Chrysocoma ciliata and succulents (mostly Mesembryanthemaceae) but few perennial grasses were present. On the other hand, roughly 94% of seedlings germinating from samples from the top and 63% of seedlings germinating from two slopes of Tafelberg respectively were persistent- grass or shrubby species. Roughly 89% of ephemeral species recorded from slopes' samples germinated from the lowest footslope sites. Seed densities were closely linked to micro-habitats with roughly three-fold differences between open- (lower seed density) and closed-canopy (higher seed density) micro-sites. Multivariate analysis of variance (MANOVA) indicated that most of the variation in seed density data was explained at the micro-habitat level. Seasonality played a secondary role with significant twoway interaction between the two effects. It is concluded that both factors must be considered when developing restoration programmes that aim to improve both overall plant cover and improved plant species diversity. While the original or "pristine" state of vegetation composition and seed banks on the plains is unknown, concems were raised regarding the apparently degraded state of total above- and below-ground plant diversity on these plains. A likely consequence of habitat degradation is that species with specific soil-, nutrient ratio-, aspect- and altitudinal requirements from the top and slopes of Tafelberg (as well as from nearby plains' refugia) may not be able to establish in degraded habitats on the plains. The identification of pioneer plant species (tolerant of habitat degradation) that allow increased vegetation cover and safe-sites for seedling germination of desirable plant species is recommended. Restoration programmes will need to be coupled with strict grazing management principles that allow seedling germination. establishment and successful reproductive output of desirable plants for future rangeland regeneration. Common and salient features of the soil habitat, plant pbenological response and germination trial studies are brought together in an examination of habitats and related seed bank diversity on- and off Tafelberg. Acknowledging the brevity of this research study, but utilising case studies from elsewhere and integrating both lines of questioning, the conclusion is again reached that the plains surrounding Tafelberg are degraded through decades and probably centuries of grazing by domestic livestock. It is considered crucial that restoration through improvement (or rehabilitation) of habitats and increased seedling safe-sites be considered. Both climate and grazing management appear to play an irrevocably linked role in shaping vegetation composition in rangelands. While rangelands are intrinsiCalfy adapted to surviving extremes of climatic variability found in non-equilibrium regions it is argued that the impacts of grazing, particularly during times of drought and climate change, are slowly reducing the intrinsic "buffer-capacity" of rangelands to withstand these changes and extremes. It seems apparent from research elsewhere that restoration through passive management is slow and probably not economically achievable within a viable time frame. The instifution and promotion of integrated and strategic programmes that identify and address issues of land degradation and land use change in semi-arid rangelands is recommended. The input and endeavours of different authorities, ministries and a broad public participation incentive are encouraged in these proposed programmes in order to ensure broadly-based input into long term sustainability and conservation of the considerable biological diversity of these regions. Seed bank assessment is considered to be a valuable means of indicating restoration potential and ranqeland condition with potential for the identification of both degraded and conservationworthy areas. Finally, some limitations and challenges of this study are examined through a process of firstly identifying alternative approaches to research methodologies and secondly through proposing recommendations for future research projects. While alternative methods could have been applied for the purposes of accomplishing this study it is concluded that, within the given time- and other constraints, the appropriate methods were applied. / AFRIKAANSE OPSOMMING: Die samestelling entoestand van groncbbewaarde saadbanke.op en van die mesa Tafelberg af, in die Nama Karoo weiveld van die Oos-Kaap, Suid-Afrika, is ondersoek binne die konteks van 'n wyer herstelekologieprojek: "Restourasie van oorbeweide Nama Karoo weiveld: die rol van bewannqseilande'". Die uitqanqspunt van hierdie saadbankondersoek was dat dit moontlik is om beskadigde semidroë weiveld te herstel deur middel van toegepaste bestuursprogramme wat gebaseer is op die metodologie en praktyk van ekologiese herstel. Algemeen erkende eienskappe van nieekwilibrium- omgewings (byvoorbeeld onvoorspelbare klimate en wisselende mates van versteuring) en grond-bewaarde saadbanke (byvoorbeeld ruimtelike en temporale verspreidings), het die basis gevorm vir die ondersoek van die algemene omgewing en die eienskappe van bestaande saadbanke in die Tafelberg omgewing. Die potensiële rol van heuwels as skuilplek vir aanvaarbare plantspesies was 'n onder1iggende element van die ondersoek. Na 'n kort ondersoek van historiese ~n kontemporêre navorsing en beleid oor weiveldbeskadiging in semi-droë streke van die wêreld, is die fundamentele behoefte aan omvattende en toegepaste saadbanknavorsing in die Nama Karoo beklemtoon. Binne die raamwerk van die oorkoepelende projek het die saadbankondersoek plaaslike omgewingskriteria bestudeer, beginnende met 'n ondersoek na saadbank- en plantegroeihabitats. Chemiese en fisiese eienskappe van grond vanaf twee en twintig terreine op en van Tafelberg af is beskryf. Omvattende grondhabitatwisseling tussen die kruin, die noordwestelike hange en die vlaktes en die suidoostelike hange en vlaktes van Tafelberg is geïdentifiseer. Mikroterreinwisseling tussen die oop-dak (tussenplantruimtes) en toe-dak (onderplantdekking) -mikrohabitats is as beduidend bevind. Primêre grondhabitatverskille is gekoppel aan die inhoud van die grond se organiese materiaal, wat op die vlaktes as laag bevind is vergeleke met die kruin en hange; en laag bevind is in oop-dak-mikroterreine vergeleke met toe-dak-terreine, Daar is gevind dat die grondtekstuur en voedingstofsamestelling op en van Tafelberg af aansienlik varieer, met beduidende verskille tussen die kruin en die vlaktes, en ook tussen die noordwestelike en suidoostelike vlaktes. Daar is gevind dat die hange intermediêr is (toon 'n mate van gradiënt) tussen die kruin en die vlaktes. Die wisseling in grondvoedingstowwe is vertolk as 'n funksie van teksturele en ouermateriaaleienskappe van grond. Antropogeniese faktore vir versnelde erosie, neerslag, loging en soutkorsvorming is ook oorweeg. Die gevolgtrekking is gemaak dat terwyl die eienskappe van grond op en van Tafelberg af inherent aan ouergrond verwant is, kan veranderinge aan tekstuur en voedingstofeienskappe voorkom, en hierdie veranderinge kon deur hoë vlakke van weiding vererger gewees het. 'n Ondersoek (wat op klein struike gefokus het) van plantfenologiese reaksie met betrekking tot reënval en weidingsgradiënte het tendense van piekbot- en blomseisoene na reënval gedurende die somer en herfs onderskeidelik geïdentifiseer. 'n Kontinuum van saadskietaktiwiteit, met piektye in laat herfs en vroeë winter, is van kwartaallikse data saamgestel. Groeistuwing is vir die meeste klein struike waargeneem gedurende lente-, herfs- en someropnames. Aangesien die een of ander vorm van aktiwiteit met betrekking tot voortplantingsgroei (groeistuwing, bot, blom of saadskiet) op feitlik al die tye van die jaar sigbaar was, word daar geredeneer dat hoëintensiteitversteuring (ook weiding) 'n negatiewe impak op plantoorlewing kan hê, wat sal lei tot verminderde voortplantingsinset (m.a.w. sade) in toekomstige geslagte. Plantgemeenskappe op die kruin en vlaktes word beskryf met beduidende verskille tussen plantegroei op die kruin van Tafelberg (wat hoofsaaklik bestaan uit hoëproduksie, smaaklike gras- en struikspesies) en dié ap die vlaktes (wat bestaan uit hoofsaaklik doringagtige, efemere, toksiese en laeproduksie-spesies). Gegee die hoë weidingsdruk op die vlaktes (vergeleke met die minder benutte hange en kruin van Tafelberg), word verskille in die samestelling van plantegroei bespreek met betrekking tot studies elders wat beskadigde weiveld beskryf. Die gevolgtrekking word eerstens gemaak dat die vlaktes om Tafelberg beskadig is, tweedens dat langtermyn-oorbenutting die samestelling van die plantegroei verander het, en laastens dat interweiding-rusperiodes van drie tot ses maande alleen dalk nie die diversiteit van plantegroei of die verlangde plantspesies op die vlaktes kan herstel nie. Die uitslae van kiemingstoetse (wat ondersoek ingestel het na grond-bewaarde saadbanke) van twee steekproefepisodes (lente en herfs 1'998)het getoon dat saadbanke in grond wat van die vlaktes, hange en kruin van Tafelberg verwyder is, die verspreidingspatrone volg wat in bogrondse plantegroei waargeneem is. Spesie-spesifieke data is nie vir hierdie tesis gefinaliseer nie, aangesien nie alle saailinge binne die gegewe tydsbeperkinge gegroei en geblom het nie. Ten einde saailing-verskyningsdata te vergelyk, is plantkategorieë ontwikkel wat efemere en langdurige (meerjarige) spesies en dikotiele spesies en grassoorte en ander monokotiele plante onderskei. Steekproewe van die kruin en teen die middelste en boonste hange het 'n hoë persentasie van aanvaarbare en standhoudende gras- en struikspesies getoon wat in grond-bewaarde saadbanke teenwoordig is, terwyl meer as twee derdes van plante wat in die vlaktes se grondmonsters ontkiem het, efemere spesies was, en die meeste daarvan was klein «5cm) en met 'n kort leeftyd «3 maande). Die meeste van die meerjarige spesies wat van die vlaktes se steekproewe kom, was saailinge van Pentzia incana, Chrysocoma ciliata en vetplante (hoofsaaklik Mesembryanthemaceae), maar min meerjarige grasse was teenwoordig. Daarenteen was onderskeidelik ongeveer 94% van saailinge wat van monsters van die kruin en 63% van saailinge wat van twee van die hange van Tafelberg ontkiem het, langdurige gras- of struikspesies. Ongeveer 89% van die efemere spesies wat van die hange se steekproewe aangeteken is, het op die laagste voethang-terreine ontkiem. Saaddigthede toon 'n noue verband met mikrohabitats, met ongeveer drievoudige verskille tussen oop- (laer saaddigtheid) en toe-dak (hoër saaddigtheid) -mikroterreine. 'n Multivariaatontleding van variansie (MANOVA) het aangedui dat die meeste van die variasie in saaddigtheidsdata op die mikrohabitat-vlak verduidelik is. Seisoenaliteit het 'n sekondêre rol gespeel, met beduidende tweerigting-interaksie tussen die twee uitwerkings. Die gevolgtrekking word gemaak dat albei faktore oorweeg moet word wanneer herstelprogramme ontwikkel word wat ten doel het om algehele plantbedekking en die diversiteit van verbeterde plantspesies te verhoog. Terwyl die oorspronklike of "ongerepte" toestand van die plantegroei se samestelling en saadbanke op die vlaktes onbekend is, is kommer uitgespreek oor die klaarblyklik beskadigde toestand van die totale bo- en ondergrondse plantdiversiteit op hierdie vlaktes. 'n Waarskynlike gevolg van habitatbeskadiging is dat spesies met spesifieke grond-, voedingstofverhouding-, aspek- en seevlak-vereistes van die kruin en hange van Tafelberg (asook van nabygeleë vlakteskuilings) nie in staat sal wees om in beskadigde habitats op die vlaktes te vestig nie. Die identifikasie van pionierplantspesies (verdraagsaam vir habitatbeskadiging) wat verhoogde plantegroeidekking en veilige terreine vir saailingontkieming van verlangde plantspesies toelaat, word aanbeveel. Herstelprogramme sal gekoppel moet word aan streng weidingsbeginsels wat saailingontkieming, die vestiging en suksesvolle voortplantingsproduksie van gewenste plante vir toekomstige weiveldherstel moontlik maak. Algemene en belangrike eienskappe van die grondhabitat, plantfenologiereaksie en kiemingsproefondersoeke word saamgevoeg in 'n ondersoek van habitats en verwante saadbankdiversiteit op en van Tafelberg af. Met erkenning van die kortstondigheid van hierdie navorsingsondersoek, maar met benutting van gevallestudies van elders en die integrasie van albei vraaglyne, word daarweertot die slotsom gekom dat die vlaktes om Tafelberg beskadig is deur dekades en waarskynlik eeue se beweiding deur mak lewende hawe. Dit word as uiters belangrik beskou dat herstel deur verbetering (of rehabilitasie) van habitats en 'n groter aantal saailing beveiligingsterreine oorweeg moet word. Dit lyk asof klimaat sowel as weidingsbestuur 'n onherroeplik gekoppelde rol speel in die vorming van die samestelling van plantegroei op weiveld. Terwyl weiveld intrinsiek aangepas is by die oorlewing van uiterste klimaatswisseling wat in nie-ekwilibriese streke aangetref word, word daar geredeneer dat die impak van beweiding, veral gedurende droogtetye en klimaatsverandering, stadigaan die intrinsieke "buffervermoë" van weiveld verminder om hierdie veranderinge en uiterstes te weerstaan. Dit blyk uit navorsing elders dat herstel deur passiewe bestuur stadig en waarskynlik nie ekonomies haalbaar is binne 'n lewensvatbare tydsraamwerk nie. Die instelling en bevordering van geïntegreerde en strategiese programme wat kwessies van grondbeskadiging en verandering van grondgebruik in semi-droë gebiede identifiseer en oplos, word aanbeveel. Die insette en pogings van verskillende owerhede en ministeries en deelname deur die breë publiek word aangemoedig in hierdie voorgestelde programme ten einde insette met 'n breë basis in die langtermyn~volhoubaarheid en bewaring van die aansienlike biologiese diversiteit van hierdie streke te verseker. Saadbankbeoordeling word beskou as 'n waardevolle manier om die herstelpotensiaal en weiveldtoestande met die potensiaal vir die identifisering van beskadigde sowel as bewaringswaardige gebiede aan te dui. Laastens word 'n paar beperkings en uitdagings van hierdie studie ondersoek deur 'n proses van eerstens die identifisering van alternatiewe benaderings tot navorsingsmetodologieë, en tweedens deur die voorstel van aanbevelings vir toekomstige navorsingsprojekte. Terwyl alternatiewe metodes toegepas kon gewees het ten einde hierdie studie af te handel, is die gevolgtrekking dat die toepaslike metodes binne die gegewe tyd5- en ander beperkings toegepas is.

Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2005. / Within the Table Mountain National Park (TMNP), Western Cape, South Africa, various management practices have been undertaken in the removal of alien vegetation. While considerable success in the control of alien plants is evident from the removal of standing plants, it is not known if this effort has actually made any long-term difference in the effort to eliminate alien vegetation from the TMNP. This is because no coordinated effort has been made to assess the extent of the alien seed bank, nor the effect that clearing (including the use of fire) has on this seed store. This study investigates the extent of pre- and post-fire Acacia saligna seed banks under differing stand ages, differing clearing techniques and different habitats in the Cape Peninsula National Park. Firstly, the focus is on two alien plant management techniques: The first technique involves clearing and stacking of biomass for burning during winter (stack burn technique), the second technique involves burning of standing alien plants (standing/block burn technique) to decrease heat release at the surface. Secondly, the extent of Acacia species seed banks along the Silvermine River is also investigated with the aim of determining the extent of alien seed stores in this habitat and therefore the long-term restoration potential of the riparian corridor. The primary question addressed in the first study is: “Under what clearing technique will most of the alien seed bank be reduced?” The secondary question reads: “Is seed bank density and distribution directly related to age of dense infestation of the alien vegetation stand and habitat?” The primary question addressed in the second study is: “What is the vertical, lateral and longitudinal distribution and density of Acacia species seed banks along the Silvermine River?” The secondary question reads: “Is seed density and distribution influenced by above ground density of alien vegetation?” In both riparian and terrestrial systems, alien soil seed banks accumulate in high densities where aboveground alien Acacia vegetation is dense. Most of the seed occurs in the upper soil layer, but seed density decreases with depth with an exception of a high seed density at a low depth in one of the samples in the riparian system. Intense fires are most effective in reducing seed stores and removing aboveground alien vegetation in both riparian and terrestrial fynbos systems. After burns, both stack and stand burns have shown a significant decrease in seed density especially in the upper layers but there is still much seed that remained in the matrix area between stacks. The cooler winter burns resulted in less destructive, lower temperatures that aided higher seedling recruitment. Mature stands of Acacia saligna tend to have greater seed stores than immature stands and habitats with deep colluvial soils have a greater density and also greater vertical distribution of seeds. The vertical distribution of the riparian system differed from the fynbos terrestrial system in that seeds were found down to lower depths. Along the river, seed density also increased laterally with more seeds occurring in the terrrestrial sections than in the channel. Seed density increased with longitudinal distribution with more seeds occurring at the sites in the lower catchment than upper catchment. Managers should be aware that fire is needed to reduce the seed bank in both riparian and terrestrial fynbos systems. The cooler winter stack burns is the best option as it results in less destructive, lower temperatures that aids higher seedling recruitment. It is important to know the site history as age of dense infestation, number of fires and geology of site could influence seed bank density. In riparian systems the vertical distribution of seed is deeper than in the fynbos area. In order for clearing to be effective it is imperative that follow-up takes place and should be done prior to flowering to stop reseeding.

Student Number : 9202137P - MSc Dissertation - School of Animal, Plant and Environmental Studies - Faculty of Science / The Reconstruction and Development Programme’s Mpumalanga Working for Water Programme (WWP) has cleared exotic and commercial weed species from the riverine environment since 1994. This study serves as an assessment of the impact and modification caused as a result of invasion and the subsequent clearing of the exotic vegetation on flora in the riverine zone of the Sabie River Catchment. The experimental design compares the before and after clearing effects and includes altitude and invasion intensity variables. The investigations included: in situ soil seed banks, environmental modification, vegetation structure, species diversity and effectiveness of clearing. Clearing and invasion by exotic species altered soil chemical, physical and ground cover parameters. The extent of these modifications was dependent on the extent of invasion and clearing done within the community. Clearing of exotic species however, acted as an additional disturbance to that caused by invasion. Environmental modifications that occurred with clearing and invasion within the study were positively related to percentage soil organic matter, and ground cover (soil, litter, vegetation). Invasion by exotic species alters the vegetation structure, the extent of which was directly related to the invasion intensity. The main source of vegetation structure modification is attributed to tall growing exotic species such as Eucalyptus grandis and Solanum mauritianum. Both of these species dominated the indigenous vegetation, E. grandis by expanding the upper canopy and S. mauritianum by dominating the mid canopy. Clearing of invasive vegetation resulted in an additional disturbance proportional to the extent of invasion intensity. Invasion did not result in any large changes to the vegetation at low intensity but clearing at this intensity increased the disturbance and altered the vegetation structure. Soil seed banks were limited in the number of species and dominated by two exotic species. The soil seed bank of woody species related positively to the community species richness. The total soil seed bank density did not relate to invasion intensity or clearing thereof but propagules of individual species within the soil seed banks did. The seeds of the exotic species, Acacia mearnsii and S. mauritianum, illustrated burial as prerequisite for persistence in the soil seed bank. A. mearnsii and S. mauritianum seeds were found to have half-life’s of up to 25 years and 13 months respectively. The species richness and diversity varied only marginally because of invasion and clearing. Species alpha diversity increased with clearing due to weedy and pioneer species establishment. Beta diversity effectively highlights the species turnover with clearing and invasion. Success in eradication of exotic species had mixed results. Clearing of high invasion sites was effective but in lower invasion categories a number of exotic individuals were missed. Clearing effectiveness was good for certain species such as E. grandis and Pinus patula, but poor for others such as S. mauritianum. Coppicing is a significant issue for E. grandis and S. mauritianum. The persistence of individuals (coppicing & missed individuals) coupled with very large persistent seed banks has repercussions for the clearing programme, as it may prevent effective eradication. Initially the WWP has been successful in removing exotic vegetation, however there is a failure to address the regenerative properties of some exotic species. Unless a rigid schedule of follow up clearing treatments occurs, an even larger invasion problem could exist.

Em empresas florestais que plantam florestas de rápido crescimento voltadas ao abastecimento industrial, é comum, hoje em dia, a existência de áreas de plantios comerciais que devem ser revertidos para áreas de vegetação natural. Entretanto, dependendo das condições locais e do contexto da paisagem, nem sempre os processos naturais de regeneração são suficientes para garantir que a vegetação natural se desenvolva e se auto-sustente nessas áreas. Este estudo avaliou os processos de regeneração natural e a efetividade de algumas técnicas de restauração florestal para indicar a melhor estratégia aplicável em larga escala, em áreas anteriormente manejadas com as culturas de Eucalyptus sp e Pinus sp, que foram abandonadas com o intuito de serem incorporadas como reservas legais. O projeto foi desenvolvido no município de Borebi, SP, em duas fazendas, sendo uma em ecossistema de cerrado latu sensu e outra de floresta estacional semidecidual. Em cada área foi instalado um experimento em blocos ao acaso, com cinco repetições e cinco tratamentos, com parcelas de 30 x 30m. Os tratamentos foram: T1: controle, T2: semeadura direta de dez espécies florestais de rápido crescimento; T3: plantio convencional de 19 espécies florestais de crescimento lento, médio e rápido; T4: condução da regeneração natural através de tratos silviculturais e T5: picagem da cobertura vegetal e revolvimento do solo. A regeneração natural de indivíduos lenhosos existente foi levantada em duas classes: altura a 1,30 m (parcela toda) e altura > que 0,50m e < que 1,30m (em três subparcelas de 1 x 30m ), antes e após (12 meses) a implantação dos tratamentos. O banco de sementes do solo foi amostrado antes da instalação e duas vezes após, e o solo superficial retirado de uma área de 315cm² e profundidade de 5cm, formando duas amostras compostas por parcela. Para a chuva de sementes foram instalados cinco coletores por parcela, com dimensões de 0,50 x 0,50m cada. Tanto o banco como a chuva de sementes apresentaram baixa porcentagem de espécies lenhosas e alta densidade de algumas espécies herbáceas invasoras. A regeneração natural apresentou espécies típicas da fase inicial da sucessão, com predomínio de espécies não constituintes. A maior similaridade na composição das espécies ocorreu na comparação entre a vegetação e a chuva de sementes e a menor na comparação da vegetação com o banco de sementes. O tratamento T4 (condução da regeneração) apresentou efeito significativo na área basal, densidade, número de espécies e diversidade de espécies da regeneração natural, em ambas as áreas, após 12 meses de implantação, mostrando-se mais viável ecologicamente e economicamente em relação aos demais. / In Forest Companies that cultivate fast-growing forest species for industrial supply, it has been usual the existence of commercial production areas that need to be converted in protected areas with native vegetation. Nevertheless, depending on local conditions and landscape context, the natural regeneration process is not enough to guarantee the successional development This work aimed at investigating the natural regeneration process and the effectiveness of some forest restoration techniques to be applied in large scale in, former Eucalyptus sp and Pinus sp plantations, which were abandoned to be incorporated as protected areas. The project was developed at Borebi municipality, SP, in two forest farms, one comprising latu sensu savana formations, and the other corresponding to seasonal semideciduous forest. In each experimental area a complete randomized block experiment with five treatments and five replicates was installed, with 30 x 30 m plots. The treatments were: T1: control; T2: direct seeding of 10 fast growing forest species; T3: conventional planting of 19 species with different growth characteristics; T4: management of natural regeneration by silvicultural treatments; T5: tillage of ground vegetation cover and plowing. Natural regeneration was surveyed before and 12 months after the experiment installation, when all woody individuals with height 1.30m were measured; the individuals with height 0.50m and <1.30m were surveyed in three 1 x 30m subplots within each plot. The soil seed bank was sampled before and two times after the treatments, were 315cm² and 5cm depth samples formed 2 composite samples by each plot. Seed rain was studied by five 0,50 x 0,50m litter traps installed in each plot. The soil seed bank and seed rain had a low percentage of woody species and high density of some nonconstituent invasive herbaceous species. The natural regeneration showed a predominance of early successional species, but was dominated by nonconstituent species. The higher similarity in species composition occurred between the natural regeneration and the seed rain, and the smaller between the natural regeneration and the soil seed bank. The regeneration management treatment (T4) showed a significant effect in basal area, density, species diversity and species richness of natural regeneration after 12 months, indicating to be the most viable ecologically and economically in comparison with the other, for the local conditions.

Studies of seed dynamics and seedling establishment at the community level in savanna ecosystems are scant, particularly in the tropical savannas of Central Brazil. The Brazilian savannas (cerrado) have the largest diversity of plant species among Neotropical savannas. Cerrado vegetation exhibits consistent changes in tree density and tree size along shallow topographic gradients. Vegetation types differ from closed savannas with high tree density, and a nearly continuous canopy cover in the uppermost portions, to open savannas with scattered short trees in the low portions of the topographic gradients. Whether or not dynamics of seeds and seedlings of woody species are consistent with variations in tree density and tree canopy cover across the cerrado landscape has not been determined, but could potentially influence such spatial patterns of tree density and canopy cover. The main objective of this study was to evaluate seed dynamics (i.e., seed rain, soil seed banks, and seed characteristics) and seedling establishment of woody species in three major cerrado vegetation types (closed, intermediate and open savannas) which differ in tree canopy cover and tree height. These vegetation types are located along topographic gradients of approximately 30 m in elevation and 1000 m in length. I conducted field work from June 2005 to August 2008 at the Instituto Brasileiro de Geografia e Estatística (IBGE) reserve, a field experimental station located 35 Km south of Brasilia, Brazil (15˚ 56' S, 47˚ 63' W, altitude 1100 m). I established permanent plots in each of the three vegetation types to assess seed rain, seed limitation, seed predation, and seed removal. I also quantified density and composition of the soil seed bank in each vegetation type and studied seed characteristics (i.e., kind of dormancy, moisture content, longevity) of 14 common cerrado woody species. In the field, I quantified establishment of woody seedlings in fire-protected savannas as well as in accidentally burned and frequently burned savannas. In the greenhouse I performed experiments to evaluate the effect of litter cover and light level on seedling emergence of 9 common cerrado woody species. Finally, I evaluated the effect of pulses of heat on seed germination of 5 common cerrado woody species under controlled conditions. The overall results of this study show that regardless of tree canopy cover, cerrado vegetation types are limited in seeds and seedlings of woody species, but these limitations are higher in open than in closed savannas. Most woody species do not form persistent soil seed banks along cerrado vegetation types because their seeds are short-lived, predated and quickly removed from the ground. In addition, dispersal season and dormancy appear to control timing of germination at the onset of the rainy season to ensure survival of seedlings in the field. In the absence of fire, establishment of woody seedlings is higher in closed than in open savannas because canopy cover mitigates the stressful environmental conditions of open savannas and thus facilitates establishment of woody seedlings. As a result, closed savannas are likely to maintain higher density of woody elements over time than open savannas. In burned savannas, however, species composition of woody and herbaceous seedlings is significantly affected because establishment of seedlings of woody and herbaceous species decreases but vegetative reproduction increases. This dissertation study indicates that interactions of early life-history stages of woody species with environmental and disturbance factors appear to play a more significant role in maintaining woody cover variations along cerrado topographic gradients than previously recognized.

[Truncated abstract] Weeds are a major limitation to agricultural and horticultural production and the main method of control is the use of herbicides. In addition to the resulting chemical pollution of the environment, the wide spread and continues use of herbicides have resulted in many weeds developing resistance to commonly used herbicides. This study investigated the potential of using green manures as a cultural method of control of weed invasion in agricultural fields. To understand the general mechanisms involved in the suppression of seed germination in green manure amended soils, seeds of crop species with little or no dormancy requirements were used in certain studies. Lettuce (Lactuca sativa) and cress (Lepidium sativum) seeds were sown to a sandy soil amended with green manures of lupin (Lupinus angustifolius), Brassica juncea, or oats (Avena sativa) to determine if the amendments affected seed germination and/or decay. It was hypothesised that the addition of plant material would increase the microbial activity of the soil thereby increasing seed decay, under laboratory and greenhouse conditions. Initial experiments used lettuce, cress and lupin seeds. Lettuce and cress are commonly used as standard test species for seed viability studies. Subsequent experiments used seeds of annual ryegrass (Lolium rigidum), silver grass (Vulpia bromoides), wild radish (Raphanus raphanistrum) and wild oat (Avena fatua) as these weed species are commonly found throughout agricultural regions in Western Australia. Amending the soil with lupin or Brassica green manure was established as treatments capable of developing environments suppressive to seed germination. Lupin residues as green manure showed the strongest inhibition of seed germination and seed decay. The decay of certain seeds was enhanced with changes to soil microbial activity, dissolved organic carbon and carbon and nitrogen amounts in lupin amended soil. Seeds of weed species were decayed in lupin amended soil, but showed varied degree of decay. Annual ryegrass and silver grass were severely decayed and wild oat and wild radish were less decayed, in lupin amended soil.

Zugl.: Freiburg (Breisgau), Univ., Diss.

Em empresas florestais que plantam florestas de rápido crescimento voltadas ao abastecimento industrial, é comum, hoje em dia, a existência de áreas de plantios comerciais que devem ser revertidos para áreas de vegetação natural. Entretanto, dependendo das condições locais e do contexto da paisagem, nem sempre os processos naturais de regeneração são suficientes para garantir que a vegetação natural se desenvolva e se auto-sustente nessas áreas. Este estudo avaliou os processos de regeneração natural e a efetividade de algumas técnicas de restauração florestal para indicar a melhor estratégia aplicável em larga escala, em áreas anteriormente manejadas com as culturas de Eucalyptus sp e Pinus sp, que foram abandonadas com o intuito de serem incorporadas como reservas legais. O projeto foi desenvolvido no município de Borebi, SP, em duas fazendas, sendo uma em ecossistema de cerrado latu sensu e outra de floresta estacional semidecidual. Em cada área foi instalado um experimento em blocos ao acaso, com cinco repetições e cinco tratamentos, com parcelas de 30 x 30m. Os tratamentos foram: T1: controle, T2: semeadura direta de dez espécies florestais de rápido crescimento; T3: plantio convencional de 19 espécies florestais de crescimento lento, médio e rápido; T4: condução da regeneração natural através de tratos silviculturais e T5: picagem da cobertura vegetal e revolvimento do solo. A regeneração natural de indivíduos lenhosos existente foi levantada em duas classes: altura a 1,30 m (parcela toda) e altura > que 0,50m e < que 1,30m (em três subparcelas de 1 x 30m ), antes e após (12 meses) a implantação dos tratamentos. O banco de sementes do solo foi amostrado antes da instalação e duas vezes após, e o solo superficial retirado de uma área de 315cm² e profundidade de 5cm, formando duas amostras compostas por parcela. Para a chuva de sementes foram instalados cinco coletores por parcela, com dimensões de 0,50 x 0,50m cada. Tanto o banco como a chuva de sementes apresentaram baixa porcentagem de espécies lenhosas e alta densidade de algumas espécies herbáceas invasoras. A regeneração natural apresentou espécies típicas da fase inicial da sucessão, com predomínio de espécies não constituintes. A maior similaridade na composição das espécies ocorreu na comparação entre a vegetação e a chuva de sementes e a menor na comparação da vegetação com o banco de sementes. O tratamento T4 (condução da regeneração) apresentou efeito significativo na área basal, densidade, número de espécies e diversidade de espécies da regeneração natural, em ambas as áreas, após 12 meses de implantação, mostrando-se mais viável ecologicamente e economicamente em relação aos demais. / In Forest Companies that cultivate fast-growing forest species for industrial supply, it has been usual the existence of commercial production areas that need to be converted in protected areas with native vegetation. Nevertheless, depending on local conditions and landscape context, the natural regeneration process is not enough to guarantee the successional development This work aimed at investigating the natural regeneration process and the effectiveness of some forest restoration techniques to be applied in large scale in, former Eucalyptus sp and Pinus sp plantations, which were abandoned to be incorporated as protected areas. The project was developed at Borebi municipality, SP, in two forest farms, one comprising latu sensu savana formations, and the other corresponding to seasonal semideciduous forest. In each experimental area a complete randomized block experiment with five treatments and five replicates was installed, with 30 x 30 m plots. The treatments were: T1: control; T2: direct seeding of 10 fast growing forest species; T3: conventional planting of 19 species with different growth characteristics; T4: management of natural regeneration by silvicultural treatments; T5: tillage of ground vegetation cover and plowing. Natural regeneration was surveyed before and 12 months after the experiment installation, when all woody individuals with height 1.30m were measured; the individuals with height 0.50m and <1.30m were surveyed in three 1 x 30m subplots within each plot. The soil seed bank was sampled before and two times after the treatments, were 315cm² and 5cm depth samples formed 2 composite samples by each plot. Seed rain was studied by five 0,50 x 0,50m litter traps installed in each plot. The soil seed bank and seed rain had a low percentage of woody species and high density of some nonconstituent invasive herbaceous species. The natural regeneration showed a predominance of early successional species, but was dominated by nonconstituent species. The higher similarity in species composition occurred between the natural regeneration and the seed rain, and the smaller between the natural regeneration and the soil seed bank. The regeneration management treatment (T4) showed a significant effect in basal area, density, species diversity and species richness of natural regeneration after 12 months, indicating to be the most viable ecologically and economically in comparison with the other, for the local conditions.

Within the last two decades substantial progress has been made in understanding seed bank dynamics and the contribution of the soil seed bank to a post-disturbance plant community. There has been relatively little progress, however, in understanding perennial bud bank dynamics and the contribution of the soil bud bank to secondary succession. This lack of information is due primarily to the inability to reliably identify roots, rhizomes, and lignotubers that lie dormant beneath the soil surface. This scientific investigation, therefore, addressed the issue of identification of belowground woody structures. The first objective was to develop a methodology that utilizes molecular tools to reliably identify woody plant species from subsoil tissue samples. The second objective was to create a key in which molecular markers serve as criteria for identification and differentiation of selected tree and shrub species common to the mountains of northeast Oregon and southeast Washington. Application of restricted fragment length polymorphism (RFLP) analysis on polymerase chain reaction (PCR)-amplified rbcL gene products proved to be a reliable method to identify and differentiate 15 plants to the genus level. Two restriction enzymes, DPN II and Hha I, cut (or do not cut) the PCR-rbcL product into one to six fragments. Fragment number and length are used to develop an identification key. Plants not analyzed in this key may share the same banding patterns , resulting in a false-positive identification of unknowns. Future research needs and management implications are discussed.

No description available.