The Brenton Blue butterfly, Orachrysops niobe (Trimen) is currently only known to be extant at one locality in the southern Cape (the Brenton Blue Butterfly Reserve = BBBR), and currently globally Red Listed as "Critically Endangered". This research investigates the life history and ecological interactions of o. niobe and recommends management techniques for the BBBR. Adult nectar sources and female oviposition behaviour are described. The first two larval instars feed on the leaflets of the host plant Indigofera erecta Thunb., and the 3rd and 4th instar larvae feed on this plant's woody rootstock, attended by ants Camponotus baynei Arnold. Cannibalism takes place in the early larval stages. Adults emerge from late October - early December, from late January to early March, and occasionally there is a third brood in April. Morphological and behavioural features of the larvae are described, and larval growth patterns are compared to other polyommatines. The nature of the myrmecophilous behaviour is assessed and the phylogenetic relationships between Orachrysops, Euchrysops, Lepidochrysops, and other polyommatine genera are discussed. Ant assemblages at the BBBR are described from pitfall trap sampling and field observations of interactions between O. niobe larvae and ants. The ant assemblages at the BBBR, Nature's Valley Fynbos Reserve (NVFR) and Uitzicht 216/ 40 are compared. The potential impact of the Argentine ant at the BBBR is discussed. Adult and egg counts are used to study the population dynamics of O. niobe, leading to an estimate of the adult butterfly population and its fluctuations. A population dynamics model is constructed, and several factors impacting fecundity and mortality are assessed. Population studies on other polyommatines are compared and discussed. The morphology, reproductive biology and autoecology of the papilionoid legume I. erecta are described. An explanation is offered why the larvae of O. niobe are monophagous on this plant. Microhabitat variations cause changes in its vegetative morphology and this further explains the restricted range of O. niobe. The population dynamics of I. erecta is investigated and the effects of biotic and abiotic factors (including fire) assessed. Braun Blanquet methodology is used to sample and classify the vegetation communities at the BBBR. Ordination techniques are used to confirm the classification and to diagnose for environmental gradients. Hypotheses are generated about the ecological processes functioning at the site, and the environmental niche occupied by I. erecta. Correlations between the occurrence xxii of vegetation types and other plant species and I. erecta are sought and a strong association with Pterocelastrus tricuspidatus is demonstrated. Three study sites are described and the ecological history of the region is reconstructed. Ecosystems are no longer fully functional because natural fire regimes and megaherbivores are absent. It is suggested that O. niobe currently inhabits an interglacial refugium under stress from the current global warming trend. The remaining suitable habitat is threatened by coastal property development and environmental degradation. An increased population of o. niobe at the BBBR, and establishment of new populations is essential to avoid extinction. Management techniques are evaluated and a management strategy for the BBBR is proposed. / Thesis (Ph.D. (Environmental Science))--North-West University, Potchefstroom Campus, 2006.

The Brenton Blue butterfly, Orachrysops niobe (Trimen) is currently only known to be extant at one locality in the southern Cape (the Brenton Blue Butterfly Reserve = BBBR), and currently globally Red Listed as "Critically Endangered". This research investigates the life history and ecological interactions of o. niobe and recommends management techniques for the BBBR. Adult nectar sources and female oviposition behaviour are described. The first two larval instars feed on the leaflets of the host plant Indigofera erecta Thunb., and the 3rd and 4th instar larvae feed on this plant's woody rootstock, attended by ants Camponotus baynei Arnold. Cannibalism takes place in the early larval stages. Adults emerge from late October - early December, from late January to early March, and occasionally there is a third brood in April. Morphological and behavioural features of the larvae are described, and larval growth patterns are compared to other polyommatines. The nature of the myrmecophilous behaviour is assessed and the phylogenetic relationships between Orachrysops, Euchrysops, Lepidochrysops, and other polyommatine genera are discussed. Ant assemblages at the BBBR are described from pitfall trap sampling and field observations of interactions between O. niobe larvae and ants. The ant assemblages at the BBBR, Nature's Valley Fynbos Reserve (NVFR) and Uitzicht 216/ 40 are compared. The potential impact of the Argentine ant at the BBBR is discussed. Adult and egg counts are used to study the population dynamics of O. niobe, leading to an estimate of the adult butterfly population and its fluctuations. A population dynamics model is constructed, and several factors impacting fecundity and mortality are assessed. Population studies on other polyommatines are compared and discussed. The morphology, reproductive biology and autoecology of the papilionoid legume I. erecta are described. An explanation is offered why the larvae of O. niobe are monophagous on this plant. Microhabitat variations cause changes in its vegetative morphology and this further explains the restricted range of O. niobe. The population dynamics of I. erecta is investigated and the effects of biotic and abiotic factors (including fire) assessed. Braun Blanquet methodology is used to sample and classify the vegetation communities at the BBBR. Ordination techniques are used to confirm the classification and to diagnose for environmental gradients. Hypotheses are generated about the ecological processes functioning at the site, and the environmental niche occupied by I. erecta. Correlations between the occurrence xxii of vegetation types and other plant species and I. erecta are sought and a strong association with Pterocelastrus tricuspidatus is demonstrated. Three study sites are described and the ecological history of the region is reconstructed. Ecosystems are no longer fully functional because natural fire regimes and megaherbivores are absent. It is suggested that O. niobe currently inhabits an interglacial refugium under stress from the current global warming trend. The remaining suitable habitat is threatened by coastal property development and environmental degradation. An increased population of o. niobe at the BBBR, and establishment of new populations is essential to avoid extinction. Management techniques are evaluated and a management strategy for the BBBR is proposed. / Thesis (Ph.D. (Environmental Science))--North-West University, Potchefstroom Campus, 2006.

The fact that large herbivores, such as Rangifer tarandus, play a part in shaping its environment through grazing and trampling of the ground is widely acknowledged today, as well as that these factors have the potential of affecting regional patterns and even global climate. This study investigated whether a considerable increase in grazing by R. tarandus for 25 years resulted in any measurable effects on the diversity of plant species in tundra vegetation. We evaluated if any differences in species composition could be found, based on differences in grazing pressure and productivity of the soil. The effect of difference in grazing pressure was studied through analysis of vegetation at 30 sites, each site comparing two different classes of grazing pressure separated by a fence, and pellets from R. tarandus were counted along transects. We did not find any evidence that the difference in grazing pressure affected the species composition on either side of the fence, depending on the site. The lack of difference in plant species composition may be explained by insufficient differences in abundance of R. tarandus, insufficient time passed since the change in grazing pressure, or varying grazing seasons at the sites on either side of the fence.

Granbarkborre är en av Sveriges mest destruktiva skadeinsekter som angriper granskog. Insekten har medfört förödande konsekvenser för granskog, framför allt sedan2018 där stora arealer granskog nästan har eliminerats. Insekten trivs i varmt ochtorrt klimat. Växthuseffekten i form av värmeböljor och perioder av minskad nederbörd tros gynna denna skadliga insekt då de kan fortplanta sig flera gånger och erövra nya områden under en enda sommarsäsong. En vital och nödvändig åtgärd vid bekämpning av skadeinsekter är att föra bort angripna träd innan granbarkborren lämnar barken. Dock är det nästan omöjligt attundersöka all granskog på det traditionella sättet, det vill säga till fots eftersom detär mycket tids- och resurskrävande. I det tidiga skedet visar det angripna trädet ingabetydande färgförändringar i det synliga spektrumet inom fjärranalys, vilket försvårar tidig upptäckt. Men för att försöka göra detta möjligt ämnar det här arbetet undersöka skillnaderna hos friska och angripna träd i tid, där det användes band i detosynliga spektrumet som ShortWave Infrared. Detta användes bland annat i form avbandkombinationer, som Atmospheric Penetration och Agriculture. Dessutom utfördes empiriska experiment på olika vegetationsindex (VI) som var NormalizedSimple Ratio, Enhanced Vegetation Index, Green Chlorophyll Vegetation Index,Normalized Difference Vegetation Index, Normalized Difference Moisture Indexoch Normalized Distance RED and SWIR. I denna studie användes satellitbilder från Sentinel-2 över studieområdet i Mellansverige under månaderna maj-september från 2020 till juli 2022. Inrapporterade dataför angrepp av granbarkborren i studieområdet hämtades från databasarkiven GlobalBiodiversity Information Facility och Holmen AB. Skogsstyrelsens öppna karttjänstanvändes för att erhålla data över Sveriges skogsarter, för att säkerställa att studieområdet bestod av granskog. Genom att utföra empiriska experiment av de olika VI och bandkombinationer sompresenteras i denna studie kunde några indikationer utmärkas. På grund av problematiken med de olika påverkande faktorerna, som bland annat lokalt klimat i kombination med tröskelvärden, var det svårt att fastställa en fullständig bedömning. Vårslutsats visar att de använda vegetationsindex och de två bandkombinationer tillsammans med den spatiala upplösningen, som Sentinel-2 erbjuder, inte uppnår det someftersträvas i denna studie. Anledningen till detta var att möjligheten att identifieraenstaka sjuka träd i studieområdet saknades. / The spruce bark beetle is one of Sweden's most destructive pests that attack spruceforests. The insect has had devastating consequences for spruce forests, especiallysince 2018 where large areas of spruce forest have been almost eliminated. The insect thrives in warm and dry climates. The greenhouse effect in the form of heatwaves and periods of reduced rainfall is believed to favor this harmful insect as theycan reproduce several times and conquer new areas in a single summer season. A vital and necessary measure in combating pests is to remove infested trees beforethe spruce bark beetle leaves the bark. However, it is almost impossible to examineall the spruce forest in the traditional way, which is on foot, because it is time- andresource-consuming. In the early stage, the infested tree shows no significant colorchanges in the visible spectrum in remote sensing, which makes early detection difficult. To try to make this possible, this work intends to investigate the differences inhealthy and infested trees in time, where bands in the invisible spectrum such asShortWave Infrared were used. This was used, among other things, in the form ofband combinations, such as Atmospheric Penetration and Agriculture. In addition,empirical experiments were performed on different vegetation indices (VI) whichwere Normalized Simple Ratio, Enhanced Vegetation Index, Green ChlorophyllVegetation Index, Normalized Difference Vegetation Index, Normalized DifferenceMoisture Index and Normalized Distance RED and SWIR. In this study, satellite images from Sentinel-2 were used over the study area in central Sweden during the months of May-September from 2020 to July 2022. Reported data for attacks by the spruce bark beetle in the study area were retrievedfrom the Global Biodiversity Information Facility and Holmen AB database archives.The Forestry Agency's open map service was used to obtain data on Sweden's forestspecies, to ensure that the study area consisted of spruce forest. By performing empirical experiments of the different VI and band combinationspresented in this study, some indications could be distinguished. Due to the problems with the various influencing factors, such as local climate in combination withthreshold values, it was difficult to establish a complete assessment. Our conclusionshows that the used vegetation indices and the two band combinations together withthe spatial resolution offered by Sentinel-2 do not achieve what is sought in thisstudy. The reason for this was that the possibility of identifying individual diseasedtrees in the study area was missing.