Made available in DSpace on 2017-07-10T14:38:24Z (GMT). No. of bitstreams: 1 Dissertacao_final_Mayara_Lautert_pdf.pdf: 7030675 bytes, checksum: 86c906585a7de9f11121d0b7b2fdfcb5 (MD5) Previous issue date: 2014-08-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aimed to survey lycophyte and fern species in 4 forest fragments in western Paraná, Brazil, and it compares them to other plant formations from the Atlantic Forest biome in southern Brazil. In fragments in western Paraná, 5 lycophyte species were registered, distributed into 2 families and 2 genera. In addition to 100 fern taxa (98 species and 2 varieties), distributed into 16 families and 37 genera. The most representative families were Pteridaceae (23 spp.), Polypodiaceae (18 spp.), Aspleniaceae (13 spp.), and Thelypteridaceae (11 spp.). Among the most representative genera there are Asplenium (12 spp.), Thelypteris (10 spp.), and Blechnum (7 spp.). The occurrence of Dicksonia sellowiana stands out, it is threatened with extinction in Brazil, and this species associated with Semideciduous Seasonal forest. The similarity between areas was identified by means of cluster analysis (UPGMA and Sørensen s Index) and the relation between similarity and geographic distance was determined through Matel s analysis. The analyses revealed proximity of areas in this study to each other, but it is closer regarding fragments in Rio Grande do Sul, Brazil, providing evidence that these areas have similar environmental conditions. / Este trabalho teve como objetivo inventariar as espécies de licófitas e samambaias em quatro fragmentos florestais do oeste do Paraná e comparar com outras formações vegetacionais do bioma Mata Atlântica do sul do Brasil. Nos fragmentos do oeste do Paraná foram registrados cinco espécies de licófitas, distribuídas em duas famílias e dois gêneros. Além de, 100 táxons de samambaias (98 espécies e duas variedades), distribuídos em 16 famílias e 37 gêneros. As famílias mais representativas foram Pteridaceae (23 spp.), Polypodiaceae (18 spp.), Aspleniaceae (13 spp.) e Thelypteridaceae (11 spp.). Já entre os gêneros mais representativos, encontram-se Asplenium (12 spp.), Thelypteris (10 spp.) e Blechnum (7 spp.). Destaca-se a espécie Dicksonia sellowiana, que se encontra ameaçada de extinção no Brasil, e sua ocorrência em Floresta Estacional Semidecidual. A similaridade entre as áreas foi realizada por meio de análises de agrupamento (Cluster Analysis - UPGMA e Índice de Sørensen) e a relação da similaridade com a distância geográfica pela análise de Matel. As análises revelaram maior proximidade das áreas do presente estudo entre si, mas destas com fragmentos do Rio Grande do Sul, evidenciando que estas áreas apresentam condições ambientais semelhantes.

<p>The main objectives of this thesis are to study if a topographic wetness index (TWI) could be used as a tool for predicting the spatial distribution of vascular plant species richness in the boreal forest as well as to study congruence in species richness between vascular plants, liverworts, mosses and lichens. A wetness index ln(a/tanβ) based on topography was used to assign a specific TWI-value to every 20 x 20m grid in two 25 km2 boreal forest landscapes (differing in average soil pH) in northern Sweden. Soil pH is known to be influenced by groundwater and to affect plant species richness in other biomes. Therefore, the relationships between plant species richness, TWI and soil pH were also studied. </p><p>The results showed that the majority of the investigated boreal forest landscapes were relatively dry and species-poor, whereas interspersed patches linked to areas with relatively high TWI had species-rich vegetation including the species of the drier parts of the landscape. There was a positive relationship between species richness of vascular plants and the TWI in both landscapes, but varied with average soil pH. TWI explained 30 % and 52 % of the variation in plant species richness in the landscape with lower and higher pH, respectively. The proportion of regionally uncommon plants also increased with TWI. Testing different calculation methods of the TWI resulted in a large variation in correlation strengths between the various TWI-values and different measured variables (species richness of vascular plants, soil pH, groundwater flow and soil moisture). The relationship between plant species richness and TWI could be further improved with some of the calculation methods. </p><p>When studying correlations in species richness using data sets from boreal forest in northern Sweden, strong positive correlations among vascular plants, mosses and liverworts were found, but no significant correlation between macrolichens and any of the other groups. This result could be explained by that the species number of each of the three related groups increases with ambient moisture, whereas the species number of macrolichens is weakly associated with moisture. </p><p>In conclusion, the TWI could become a useful tool in conservation management for identifying areas of special interest prior to field inventories. Since vascular plants can be used as an indicator taxon for species richness of mosses and liverworts, high TWI-values indicate areas of species hotspots of these taxa.</p> / <p>Syftet med avhandlingen är att dels studera om ett topografiskt fuktighetsindex skulle kunna vara användbart för att förutsäga fördelningen av kärlväxters artrikedom i boreal skog, dels att studera om den rumsliga fördelningen av artrikedom hos kärlväxter, blad- och levermossor samt lavar sammanfaller.</p><p>Ett fuktighetsindex, ln(a/tanβ), som bara är baserat på topografi användes för att beräkna ett indexvärde för varje 20 x 20 m grid i två 25 km2 stora boreala skogslandskap (med i medeltal olika mark-pH) i norra Sverige. Det är känt att mark-pH påverkas av grundvatten och att pH i sin tur påverkar artrikedom hos kärlväxter i andra biom. Därför studerades även sambanden mellan kärlväxters artrikedom, mark pH och TWI.</p><p>Resultaten visade att större delen av det studerade boreala landskapet var relativt torrt och artfattigt, medan mindre utspridda områden med höga TWI-värden var artrika på kärlväxter och här växte även arter som återfanns i de torra delarna av skogen. Sambandet mellan artrikedom hos kärlväxter och TWI var positivt i båda landskapen, men påverkades av de olika nivåerna på mark-pH. TWI förklarade 30 % av variationen i artrikedom i området med lägre mark-pH respektive 50 % i området med högre mark-pH. Andelen kärlväxter som klassificeras som icke vanliga i respektive region ökade också med TWI. Med andra beräkningsmetoder för TWI visade det sig att styrkan på korrelationerna mellan TWI och olika uppmätta variabler (artrikedom hos kärlväxter, mark-pH, grundvattennivå och markfuktighet) varierade mycket. Sambandet mellan artrikedom hos kärlväxter och TWI kunde förbättras ytterligare med vissa beräkningsmetoder.</p><p>Då korrelationer i artrikedom studerades användes ett dataset från boreal skog i norra Sverige. Resultaten visade på starka, positiva korrelationer mellan kärlväxter, blad- och levermossor, men inga korrelationer mellan någon av dessa grupper och lavar. Detta kunde förklaras med att artrikedom hos de tre korrelerande organismgrupperna ökar med ökad fuktighet, medan artrikedom hos lavar inte är kopplat till fukt.</p><p>Huvudslutsatsen i avhandlingen är att TWI, som endast är baserad på topograpfiskt data, skulle kunna bli ett värdefullt redskap i naturvårdsplanering för att identifiera särskilt intressanta skogsområden innan man gör fältinventeringar. Eftersom studien visar att kärlväxter kan användas som en indikator grupp för artrikedom hos blad- och levermossor indikerar höga TWI-värden områden med hög artrikedom även vad gäller dessa taxa.</p>

The main objectives of this thesis are to study if a topographic wetness index (TWI) could be used as a tool for predicting the spatial distribution of vascular plant species richness in the boreal forest as well as to study congruence in species richness between vascular plants, liverworts, mosses and lichens. A wetness index ln(a/tanβ) based on topography was used to assign a specific TWI-value to every 20 x 20m grid in two 25 km2 boreal forest landscapes (differing in average soil pH) in northern Sweden. Soil pH is known to be influenced by groundwater and to affect plant species richness in other biomes. Therefore, the relationships between plant species richness, TWI and soil pH were also studied. The results showed that the majority of the investigated boreal forest landscapes were relatively dry and species-poor, whereas interspersed patches linked to areas with relatively high TWI had species-rich vegetation including the species of the drier parts of the landscape. There was a positive relationship between species richness of vascular plants and the TWI in both landscapes, but varied with average soil pH. TWI explained 30 % and 52 % of the variation in plant species richness in the landscape with lower and higher pH, respectively. The proportion of regionally uncommon plants also increased with TWI. Testing different calculation methods of the TWI resulted in a large variation in correlation strengths between the various TWI-values and different measured variables (species richness of vascular plants, soil pH, groundwater flow and soil moisture). The relationship between plant species richness and TWI could be further improved with some of the calculation methods. When studying correlations in species richness using data sets from boreal forest in northern Sweden, strong positive correlations among vascular plants, mosses and liverworts were found, but no significant correlation between macrolichens and any of the other groups. This result could be explained by that the species number of each of the three related groups increases with ambient moisture, whereas the species number of macrolichens is weakly associated with moisture. In conclusion, the TWI could become a useful tool in conservation management for identifying areas of special interest prior to field inventories. Since vascular plants can be used as an indicator taxon for species richness of mosses and liverworts, high TWI-values indicate areas of species hotspots of these taxa. / Syftet med avhandlingen är att dels studera om ett topografiskt fuktighetsindex skulle kunna vara användbart för att förutsäga fördelningen av kärlväxters artrikedom i boreal skog, dels att studera om den rumsliga fördelningen av artrikedom hos kärlväxter, blad- och levermossor samt lavar sammanfaller. Ett fuktighetsindex, ln(a/tanβ), som bara är baserat på topografi användes för att beräkna ett indexvärde för varje 20 x 20 m grid i två 25 km2 stora boreala skogslandskap (med i medeltal olika mark-pH) i norra Sverige. Det är känt att mark-pH påverkas av grundvatten och att pH i sin tur påverkar artrikedom hos kärlväxter i andra biom. Därför studerades även sambanden mellan kärlväxters artrikedom, mark pH och TWI. Resultaten visade att större delen av det studerade boreala landskapet var relativt torrt och artfattigt, medan mindre utspridda områden med höga TWI-värden var artrika på kärlväxter och här växte även arter som återfanns i de torra delarna av skogen. Sambandet mellan artrikedom hos kärlväxter och TWI var positivt i båda landskapen, men påverkades av de olika nivåerna på mark-pH. TWI förklarade 30 % av variationen i artrikedom i området med lägre mark-pH respektive 50 % i området med högre mark-pH. Andelen kärlväxter som klassificeras som icke vanliga i respektive region ökade också med TWI. Med andra beräkningsmetoder för TWI visade det sig att styrkan på korrelationerna mellan TWI och olika uppmätta variabler (artrikedom hos kärlväxter, mark-pH, grundvattennivå och markfuktighet) varierade mycket. Sambandet mellan artrikedom hos kärlväxter och TWI kunde förbättras ytterligare med vissa beräkningsmetoder. Då korrelationer i artrikedom studerades användes ett dataset från boreal skog i norra Sverige. Resultaten visade på starka, positiva korrelationer mellan kärlväxter, blad- och levermossor, men inga korrelationer mellan någon av dessa grupper och lavar. Detta kunde förklaras med att artrikedom hos de tre korrelerande organismgrupperna ökar med ökad fuktighet, medan artrikedom hos lavar inte är kopplat till fukt. Huvudslutsatsen i avhandlingen är att TWI, som endast är baserad på topograpfiskt data, skulle kunna bli ett värdefullt redskap i naturvårdsplanering för att identifiera särskilt intressanta skogsområden innan man gör fältinventeringar. Eftersom studien visar att kärlväxter kan användas som en indikator grupp för artrikedom hos blad- och levermossor indikerar höga TWI-värden områden med hög artrikedom även vad gäller dessa taxa.

The Swedish deciduous forest has been actively replaced by coniferous forest during the last two hundred years. In Färna Ekopark, Västmanland, this trend is being reversed by restorations of deciduous forests through the removal of coniferous trees in mixed forests. This field study investigates how successful these restorations have been for plant diversity and how they were affected by past grazing and the proportion of similar mixed and deciduous forest habitats in thesurrounding landscape. Plant species richness was investigated in 370 1m2-plots distributed over 37 sample areas and the surrounding landscape analyzed in a GIS. Results show that a few years after restoration there was higher plant species richness and lower homogenization, at the site scale, compared to the controls. When the restored sites were divided into two subgroups dependant on age, the 5-6 year old restoration displayed higher plot richness than the 2-4 year old restorations, but were also more homogeneous. Past grazing showed a generally positive effect on plant diversity, and these areas also responded with a larger increase of plant species richness and less homogenous plant populations after restorations compared to areas that had not been formerly grazed. The proportion of similar deciduous and mixed forest habitats (more than 40 % deciduous trees) inthe surrounding landscape showed no effect on the plant diversity of deciduous forests in general, though it did display a weak influence over the plot richness of restored deciduous forests without a history of grazing. When restoring deciduous forests to increase plant diversity it would therefore appear wise to focuson the formerly grazed deciduous forests. To take advantage of the beneficial effects to plot richness restored deciduous forests should have a high degree of deciduous and mixed forests within one kilometer. / Den svenska lövskogen har aktivt ersatts med barrskog under de senaste tvåhundra åren. I Färna Ekopark, Västmanland, försöker man vända denna trend genom att ta bort barrträd i blandskog ochpå så sätt restaurera lövskog. Denna fältstudie undersöker om restaureringarna har gett ökad växtdiversitet och hur restaureringarna har påverkats av tidigare bete samt andelen av liknande bland- och lövskogshabitat i det omgivande landskapet. Växtartantalet undersöktes med 370 1m2-rutor utspridda över 37 områden och det omgivande landskapet analyserades i ett GIS. Resultaten visar att några år efter restaurering hade områdena högre växtdiversitet och artsammansättningen var mindre likformig i jämförelse med kontrollerna. När de restaurerade områdena delades upp i två grupper, i avseende på ålder, uppvisade de 5-6 år gamla restaureringarna högre växtdiversitet i rutorna än de 2-4 år gamla restaureringarna, men artsammansättningen var även mer likformig. Tidigare bete visade en generellt positiv inverkar på växtdiversiteten och dessa områden fick en ännu större uppgång i artrikedom och ännu lägre likformighet i artsammansättningarna efter restaureringarna än de områden som inte hade betats tidigare. Andelen av liknande bland- och lövskogshabitat (mer än 40 % lövträd) i det omgivande landskapet uppvisade ingen effekt på växtdiversiteten hos lövskog generellt, men det fanns en svag påverkan på växtdiversiteten på rutnivå hos restaurerade lövskogar utan tidigare bete. När man restaurerar lövskog för att öka växtdiversiteten verkar det därför bra att fokusera på tidigare betade lövskogar. Om man vill ta tillvara på den positiva påverkan på växtpopulationerna som omgivande landskap kan ha bör restaurerade lövskogar ha en stor andel bland- och lövskog en kilometer runt omkring sig.

The effects of fire on vernal herbs of the mesic forests of eastern North America are poorly understood. I studied the influence of prescribed fire on species richness, abundance of rare and common species, and density of exotics in the vernal herbaceous layer. To determine these effects, three sites in central Kentucky were surveyed prior to and following one of three treatments: spring burn, winter burn, or negative control. I conducted low-intensity spring burns in April 2010 and winter burns in February 2011. I used chi square analyses to test for changes in species richness, abundance of rare species, abundance of common species, and abundance of Glechoma hederacea, an exotic herb. I used multiple logistic regressions to test for the effect of burn severity on the abundance of two of the most common herbs, Erythronium americanum and Viola sororia sensu lato. The abundance of rare species increased significantly after fire treatment, with a 2% greater increase on burned plots than control plots (p < 0.05), and showed a 40% greater increase in plots burned in winter than plots burned in spring. However, there was no significant difference in overall species richness due to fire or to the season in which the prescribed fire was conducted. There were no significant differences in the density of common species or Glechoma hederacea due to fire treatment or due to fire season. There were also no significant differences in the abundances of Erythronium americanum or Viola sororia sensu lato due to burn severity. Changes in the abundance of rare species due to fire might suggest that prescribed burns may slightly increase the diversity of vernal herbs in eastern mesic forests. Changes in the abundance of rare species due to fire season might suggest that prescribed fires conducted prior to emergence may further increase the diversity of vernal herbs in the eastern mesic forest.

Die auf verschiedenen Skalen-Ebenen heterogene Verteilung des Artenreichtums fasziniert Naturforscher und Biologen seit Jahrhunderten, so dass eine Vielzahl von Hypothesen zur Erklärung dieser Muster aufgestellt wurde. Es besteht breiter Konsens darüber, dass eine Vielzahl verschiedener Prozesse für die Variation des Artenreichtums verantwortlich ist. Je nachdem welche Taxa, welche Orte und welche räumlichen und zeitlichen Skalen betrachtet werden, wird den verschiedenen Faktoren dabei eine unterschiedlich große Bedeutung zugemessen. Umweltgradienten gelten in diesem Zusammenhang als die wichtigsten, den Artenreichtum bestimmende Faktoren. Da jedoch die Landschaften und damit Habitate der Arten weltweit und vor allem in Mitteleuropa stark anthropogen überprägt sind, sollte der auf den Artenreichtum wirkende Einfluss anthropogener Interventionen in diesem Zusammenhang nicht vernachlässigt werden. Die durch den Menschen und seine Aktivitäten verursachten Landnutzungsänderungen, eine steigende Landschaftsfragmentierung und -degradation sowie die Intensivierung der Landnutzung haben sich bereits im Verlust (halb-)natürlicher Landschaftselemente, dem Rückgang der Biodiversität und der Verschlechterung von Ökosystemfunktionen niedergeschlagen; eine weitere Verschlechterung der Zustände wird vorhergesagt. In diesem Zusammenhang dient die Ausweisung von Schutzgebieten vielfach dazu, den auf die Arten und ihre Habitate wirkenden Druck zu vermindern. Da die Lage dieser Gebiete jedoch häufig nicht auf Grundlage der Kenntnis über das Vorkommen von Arten bestimmt wurde, dürfte die Effektivität der Schutzgebiete für den Artenschutz vielfach eingeschränkt sein. Die vorliegende, die norddeutschen Bundesländer Niedersachsen und Bremen umfassende Arbeit untersucht 1.) die Muster des Artenreichtums der Gefäßpflanzenarten in den beiden Ländern; 2.) die Effektivität des Schutzgebietsnetzwerks des norddeutschen Tieflands für den Schutz seltener und bedrohter Gefäßpflanzenarten und 3.) den Zusammenhang zwischen Mustern des Artenreichtums und den ihnen zugrundeliegenden Prozessen unter besonderer Berücksichtigung des anthropogenen Einflusses. Die Arbeit basiert auf einem umfangreichen, im Rahmen des Niedersächsischen Pflanzenartenerfassungsprogramms (NLWKN 1982-2003) erhobenen Datensatzes, der räumlich explizite Informationen zur Verbreitung aller in den Bundesländern vorkommenden Arten liefert. Die floristischen Daten wurden für die durchgeführten Analysen mit hochaufgelösten Daten zu Landbedeckung und Umweltbedingungen kombiniert. Damit repräsentiert die vorliegende Arbeit die erste umfassende Auswertung des umfangreichen floristischen Datensatzes. Für die Untersuchung der Muster des Gefäßpflanzenreichtums innerhalb der Untersuchungsregion wurden für die Gesamtzahl der Arten sowie für fünf auf Grundlage des floristischen Status’ und des Gefährdungsgrades der Arten zusammengestellte Untergruppen der Artenreichtum pro Landschaftseinheit (1.762 Messtischblatt-Quadranten à ca. 30 km²) berechnet. Der Artenreichtum aller Gruppen zeigte eine heterogene Verteilung in der Untersuchungsregion, wobei eine Zunahme der Artenzahlen von Nord nach Süd und zum Teil auch von West nach Ost erkennbar war. Die Zentren hoher Artenvielfalt der verschiedenen Gruppen korrelierten miteinander. Die Analyse der Effektivität der Schutzgebiete für den Schutz der seltenen und bedrohten Gefäßpflanzenarten zeigte, dass die Artvorkommen im niedersächsischen Tiefland zu einem relativ hohen Anteil durch Naturschutz- und Fauna-Flora-Habitat-Gebiete abgedeckt sind, wobei letztere Gebiete die erstgenannten sinnvoll ergänzten. Im Rahmen der Analyse konnte jedoch nicht untersucht werden, inwiefern sich der nachgewiesene effektive Gebietsschutz in einem effektiven Artenschutz niederschlägt. Der anthropogene Einfluss auf die Landschaft der Untersuchungsregion wurde im Rahmen zweier separater Analysen untersucht, wobei der Zusammenhang zwischen Artenreichtum und Landschaftsfragmentierung einerseits und dem Grad der Landschaftsmodifikation andererseits analysiert wurde. Die Landschaftsfragmentierung wurde in der vorliegenden Arbeit mittels des Landschaftsmaßes der 'Effektiven Maschenweite' (meff; engl. Effective Mesh Size Index) untersucht. Der Zusammenhang zwischen meff und dem Artenreichtum aller Gefäßpflanzenarten sowie fünf weiteren nach ihrem floristischen bzw. Gefährdungsstatus definierten Gruppen wurde mittels einer Varianzpartitionierung ermittelt, die die Effekte der Landschaftsfragmentierung von den durch Umweltvariablen und räumliche Autokorrelation der Daten verursachten Effekten separiert. Der Grad der Landschaftsfragmentierung erklärte einen signifikanten, jedoch unterschiedlich großen Anteil des Artenreichtums aller untersuchten Gruppen, wobei der stärkste Effekt für die Gruppe der Neophyten und der geringste für die Gruppe der seltenen und bedrohten Arten erkennbar waren. Eine Cluster-Analyse auf Grundlage verschiedener, die Komposition und Konfiguration der Landschaft beschreibender Landschaftsmaße identifizierte für die Modellregion einen sechsstufigen 'Landschaftsmodifikations'-Gradienten. Dieser Gradient reichte von stark fragmentierten urbanen hin zu wenig fragmentierten Landschaften mit hohem Waldanteil. Der Gesamtartenreichtum sowie die Artenzahlen von sieben verschiedenen, nach ihrem floristischen Status, ihrer Gefährdung bzw. ihrer Habitat-Bindung bestimmten Artengruppen zeigten signifikante Unterschiede entlang des Gradienten. Die Gesamtartenzahl wie auch der Reichtum der indigenen, der bedrohten sowie der an Waldlebensräume und nährstoffarme Habitate gebundenen Arten war jeweils an den Enden des Gradienten am höchsten. Der Reichtum der Neophyten sowie der an urbane Räume und nährstoffreiche Habitate gebundenen Arten nahm dagegen von den urbanen zu den wenig beeinflussten Landschaften hin ab. Die im Rahmen der Arbeit erhaltenen Ergebnisse können zukünftig als Grundlage für naturschutzfachliche Planungen in der Untersuchungsregion dienen, indem sie die Ausweisung von für den Naturschutz relevante Landschaftsräume unterstützen. Sofern entsprechende, qualitativ mit denen der vorliegenden Arbeit vergleichbare Grundlagendaten vorliegen, eignen sich die im Rahmen der Arbeit angewendeten und entwickelten Methoden, um auf andere Regionen übertragen zu werden und auch dort naturschutzfachliche und landschaftsplanerische Prozesse zu unterstützen.

Cashew, Anacardium occidentale Linnaeus, is an economically important cash crop for more than 300,000 rural households in Tanzania. Its production is, however, severely constrained by infestation by sap-sucking insects such as Helopeltis anacardii Miller, H. Schoutedeni Reuter and Pseudotheraptus wayi Brown. The African weaver ant (AWA), Oecophylla longinoda Latreille, is an effective biocontrol agent of hemipteran pests in coconuts in Tanzania; but its efficacy for the control of sap-sucking insects, especially Helopeltis spp. and P. wayi, has not been investigated so far in cashew crops in Tanzania. Field trials were carried out at the Coast region of Tanzania to evaluate the effect of seasonality and abundance of AWA on Helopeltis spp. and P. wayi. Results showed that AWA abundance expressed, as number of leaf nests per tree, and colonization of trails on main branches varied significantly between cashew-seasons and off-seasons. There was a negative correlation between numbers of nests and pest damage. AWA-colonized cashew trees had the lowest shoot damaged by Helopeltis spp., 4.8 and 7.5% in 2010 and 2011, respectively, compared to 36 and 30% in 2010 and 2011, respectively, in uncolonized cashew trees. Similarly, nut damage by P.wayi was lowest in AWA-colonized trees with 2.4 and 6.2% in 2010 and 2011, respectively, as compared to 26 and 21% in 2010 and 2011, respectively, in uncolonized trees. Interaction between AWA and dominant ant species, namely big-headed ant (BHA), Pheidole megacephala Fabricius, and common pugnacious ant (CPA), Anoplolepis custodiens Smith, was examined because of the implication that the dominant ant species may have on the efficacy of AWA in its control of sap-sucking pests of cashew. Abundance of AWA was significantly negatively correlated to BHA (r(39) = -0.30; P < 0.0001) and CPA (r(39) = -0.18; P = 0.01) at Bagamoyo in 2010. A similar trend was also observed at Mkuranga. The presence of these ant species may therefore hinder effectiveness of AWA to control sap-sucking pests in cashew in Tanzania. Therefore, suppression of these two inimical ant species should be emphasized for effective control of the sap-sucking pests in cashew fields. It was therefore also important to establish the abundance and diversity of ant species occurring in cashew agro-ecosystems. Results from pitfall traps revealed the diversity and abundance of ants in cashew agro-ecosystems: a total of 14001 ants were trapped belonging to six subfamilies, 18 genera and 32 species. The ant species diversity was high in the cashew fields at two of the four sites, namely Mkuranga A and Kibaha during both seasons. CPA was the most abundant ants in the pitfall traps. It is an important aspect that should be addressed for effective control of sap-sucking pests in cashew fields with AWA, since the correlation between AWA and CPA abundance was found to be negative. The effect of alternative fungicides to sulphur dust used for powdery mildew disease (PMD) on AWA was also investigated. No significant difference could be found in the effect ofthe different fungicides on the number of leaf nests and colonization of trails. In order to develop AWA as a component of cashew integrated sap-sucking insect management, strategies for their conservation during cashew off-seasonswas evaluated. The use of fish and hydramethylon (Amdro®) as baits increased the number of leaf nests and colonization trails of AWA over the control during off-season; however, the increase was significantly high when both fish and hydramethylon were used together. Fish and hydramethylon can therefore be used for conservation of AWA during off-season. It can therefore be concluded that AWA effectively controls sap-sucking pests on cashew and can be conserved during off-season using disposal waste such as fish intestines. Fungicides used for the control of PMD did not have detrimental effects on AWA abundance and can therefore be integrated as a component of cashew IPM. / PhD (Environmental Sciences), North-West University, Potchefstroom Campus, 2013

Cashew, Anacardium occidentale Linnaeus, is an economically important cash crop for more than 300,000 rural households in Tanzania. Its production is, however, severely constrained by infestation by sap-sucking insects such as Helopeltis anacardii Miller, H. Schoutedeni Reuter and Pseudotheraptus wayi Brown. The African weaver ant (AWA), Oecophylla longinoda Latreille, is an effective biocontrol agent of hemipteran pests in coconuts in Tanzania; but its efficacy for the control of sap-sucking insects, especially Helopeltis spp. and P. wayi, has not been investigated so far in cashew crops in Tanzania. Field trials were carried out at the Coast region of Tanzania to evaluate the effect of seasonality and abundance of AWA on Helopeltis spp. and P. wayi. Results showed that AWA abundance expressed, as number of leaf nests per tree, and colonization of trails on main branches varied significantly between cashew-seasons and off-seasons. There was a negative correlation between numbers of nests and pest damage. AWA-colonized cashew trees had the lowest shoot damaged by Helopeltis spp., 4.8 and 7.5% in 2010 and 2011, respectively, compared to 36 and 30% in 2010 and 2011, respectively, in uncolonized cashew trees. Similarly, nut damage by P.wayi was lowest in AWA-colonized trees with 2.4 and 6.2% in 2010 and 2011, respectively, as compared to 26 and 21% in 2010 and 2011, respectively, in uncolonized trees. Interaction between AWA and dominant ant species, namely big-headed ant (BHA), Pheidole megacephala Fabricius, and common pugnacious ant (CPA), Anoplolepis custodiens Smith, was examined because of the implication that the dominant ant species may have on the efficacy of AWA in its control of sap-sucking pests of cashew. Abundance of AWA was significantly negatively correlated to BHA (r(39) = -0.30; P < 0.0001) and CPA (r(39) = -0.18; P = 0.01) at Bagamoyo in 2010. A similar trend was also observed at Mkuranga. The presence of these ant species may therefore hinder effectiveness of AWA to control sap-sucking pests in cashew in Tanzania. Therefore, suppression of these two inimical ant species should be emphasized for effective control of the sap-sucking pests in cashew fields. It was therefore also important to establish the abundance and diversity of ant species occurring in cashew agro-ecosystems. Results from pitfall traps revealed the diversity and abundance of ants in cashew agro-ecosystems: a total of 14001 ants were trapped belonging to six subfamilies, 18 genera and 32 species. The ant species diversity was high in the cashew fields at two of the four sites, namely Mkuranga A and Kibaha during both seasons. CPA was the most abundant ants in the pitfall traps. It is an important aspect that should be addressed for effective control of sap-sucking pests in cashew fields with AWA, since the correlation between AWA and CPA abundance was found to be negative. The effect of alternative fungicides to sulphur dust used for powdery mildew disease (PMD) on AWA was also investigated. No significant difference could be found in the effect ofthe different fungicides on the number of leaf nests and colonization of trails. In order to develop AWA as a component of cashew integrated sap-sucking insect management, strategies for their conservation during cashew off-seasonswas evaluated. The use of fish and hydramethylon (Amdro®) as baits increased the number of leaf nests and colonization trails of AWA over the control during off-season; however, the increase was significantly high when both fish and hydramethylon were used together. Fish and hydramethylon can therefore be used for conservation of AWA during off-season. It can therefore be concluded that AWA effectively controls sap-sucking pests on cashew and can be conserved during off-season using disposal waste such as fish intestines. Fungicides used for the control of PMD did not have detrimental effects on AWA abundance and can therefore be integrated as a component of cashew IPM. / PhD (Environmental Sciences), North-West University, Potchefstroom Campus, 2013

Conservation of wood-decaying fungi requires improved knowledge about the long-term effects of forest management; regarding habitat loss, fragmentation and fire suppression. To better understand such effects, I examined the influence of area, isolation, fire history and forest stand characteristics on communities of wood-decaying fungi. Species richness and composition were studied along a gradient of 22 forested islands varying in size (0.16 to 17.58 ha) and fire history (spanning 5000 years) in a boreal forest archipelago in northern Sweden. A total of 490 records of 41 polypore species were found in 33 circular plots, each 0.1 ha in size. Species richness and the number of red-listed species were analyzed using generalized linear models (GLMs), while species composition was examined using non-metric multidimensional scaling (NMDS) ordination. The species composition was clearly different between recent-fire (&lt; 300 years since last fire) and old-fire (≥ 300 years since last fire) islands, mirroring the shift in tree species composition as pine-associated fungal species were replaced by spruce-associated fungal species. The volume of logs was the only variable influencing the species richness, although the diversity of logs showed a clear trend of also influencing species richness positively. The results demonstrate the importance of having both recent-fire and old-fire forests as landscape-level habitats and species pools, where fire naturally would constitute a key role for maintaining forest biodiversity in the boreal forest landscape. The results also stress the importance of dead wood for species richness at the individual forest stands.

What drives species diversity across landscapes is one of the most fundamental questions in ecology. Further, understanding the mechanisms underlying species diversity patterns is important not only for forming and challenging ecological theories but also essential for appropriate landscape management and effective nature conservation. This thesis focuses on patterns of vascular plant, moss and liverwort species richness and composition in relation to water flow in boreal-forest catchments, focusing mostly on riparian zones (RZs), that is terrestrial areas bordering streams and rivers. I addressed some of the most essential questions related to the ecology of riparian vegetation including the role of stream network position, groundwater (GW) flow paths, substrate availability, upland perturbations, and stream restoration. I also investigated how riparian soil processes and habitat properties relate to these factors in order to provide a holistic understanding of riparian dynamics. The results showed that the species richness and composition of riparian vascular plants, mosses and liverworts are strongly influenced by position along the stream network, GW discharge, presence of variable substrates in RZs, and by stream restoration. Generally, more species were found downstream in the network, at sites with inputs of upland GW, sites with high diversity of substrates (e.g., open mineral soil, rocks, stones, wood and bark), and along streams restored after channelization. This thesis also describes how riparian habitat properties responded to position in the landscape and human impacts, thus providing mechanistic links between plant species diversity and riparian processes across spatial scales. These ecological insights are further implemented into numerous recommendations for freshwater and upland management in boreal Sweden. Given that streams and rivers connect landscape elements both longitudinally and laterally I argue that management plans should be designed for entire catchments instead of individual river segments. Ignoring the connectivity of streams as well as the high connectivity of riparian areas to uplands via GW flows may result in failure of restoration, mitigation and/or protection actions. Further, during forestry operations more emphasis should be placed on GW discharge areas along streams and rivers, because they represent important ecological and biogeochemical hotspots in the landscape. The riparian buffers left along streams in boreal catchments affected by forestry are presently insufficiently wide and often uniform in width. This threatens the assemblages of species in GW discharge hotspots and the ecosystem services they provide. Overall, this thesis describes a holistic picture of riparian diversity patterns and riparian processes in boreal landscapes, acknowledges and elaborates on current ecological theories, presenting new patterns in biodiversity, and offers management guidelines.