Biodiversity trends (such as the relationship between species richness and temperature or productivity) are always defined for a particular taxon at a specific area (the entire range of the taxon or often just a region arbitrarily chosen by researchers). The form of these trends varies between taxa and regions. The weak relationship between richness and temperature or productivity is sometimes interpreted as a counterevidence for the hypothesis explaining diversity patterns by these variables. However, the delimitation of taxa or region may play a crucial role for the form of the trends. The aim of this thesis is to determine whether some taxon properties (its size) or region properties (its area, range of explanatory variables, the temperature-productivity relationship or average temperature) affect the strength and slope of the richness-temperature and richness-productivity relationships. 46 data sets of species richness for a wide range of plants, invertebrates and ectothermic vertebrates within different regions of the world were used for the analysis. While the taxon size is likely to affect the strength and slope of the relationship when comparing individual (nested) subclades within larger clade, the comparison of different taxa in different regions of the world shows only the effect of the region...

Durante la época lluviosa del año 2010 y la época seca del año 2011 fue examinada la composición de especies de lechuzas en la Vertiente Pacífica de Costa Rica. Se utilizó el método de estimulación con vocalizaciones coespecíficas para estimar la composición, frecuencia de detección y abundancia relativa de especies de ensamblajes de búhos y lechuzas en tres núcleos de bosque tropical secundario distribuidos en un rango de 0 m hasta 2100 m. El estudio se basó en la clasificación de zonas de vida desarrollado por Holdridge. Se registraron un total de siete especies de aves rapaces nocturnas. Se colocaros 16 puntos de muestreo en dos senderos de cada núcleo de bosque, ocho puntos por sendero. Los tres sitios variaron en cuanto a la riqueza de especies detectadas y esperadas. Las diferencias no fueron significativas entre los núcleos durante la época lluviosa, sin embargo para Strix nigrolineata y Strix virgata si hubieron diferencias durante la época seca. La similitud de especies fue mayor entre los núcleos de alturas menores, y más baja entre el bosque de tierras bajas y el bosque de tierras altas. La frecuencia de detección varía entre especie y entre núcleos de bosque, siendo Strix virgata la lechuza con mayor frecuencia de detección en tierras bajas e intermedias, y mayor abundancia en los tres núcleos de bosque. Por el contrario Lophostrix cristata tuvo menor frecuencia de detección y menor abundancia en dos de los tres núcleos de bosque estudiados durante la época lluviosa. No se detectó ningún individuo de Pulsatrix perspicilata dentro de los puntos de muestreo durante la época lluviosa, sin embargo fuera de los puntos si hubo registros / During the rainy season of 2010 and the dry season of 2011, We examined the composition of owl species within in the Pacific Slope of Costa Rica. We employed the playback survey method using conspecific vocalizations of owl species to estimate their composition, frequency of detection and relative abundance of owl species in three secondary tropical stands of forest distributed from sea level to 2100m. The study was based on the classification of life zones developed by Holdridge. A total of seven owl species were detected. We set up 16 points in two trails at each forst fragment, eight points per trail. The detected and expected species richness was different at the three forest fragments. While differences were not significant, the three stands differed in species richness; nevertheless there were differences in the dry season for Strix virgata and Strix nigrolineata, with a greater overlap of owl species among the middle/lower forest areas, and lower among the lowland forest and upland forest. The detection rate varied between species and between forest stands, with Strix virgata detected most frequently in the lowlands and intermediate lands, and with higher abundance than other owls in the three stands of forest. By contrast, Lophostrix cristata had lower frequency of detection and lower abundance in two of the three studied forests during the rainy season. We found no Pulsatrix perspicilata individuals within the sampling sites in the rainy season, however there were records outside the sample areas

Altitudinal gradients constitute a powerful test system for understanding distribution of species around the globe. Tropical mountains are quite rich in species even after controlling for environmental productivity, and are ideally suited for studying patterns of species distributions because they have had sufficient time for species to produce a response to environmental changes that affect their life histories. In this thesis, I investigate basic ecological mechanisms potentially behind avian distribution patterns along an altitudinal gradient in West-Central Africa. I used data collected with four methodological approaches (point counts, mist netting, random walks and artificial nest experiments) along an altitudinal gradient on Mt. Cameroon from October 2011 to September 2013. This work is focused on two interrelated themes: selection pressures on life histories (Chapters 1, 2, 3 & 4), and avian assemblage structures (Chapters 5 & 6). In the General Introduction, I present an overview of the study area with conservation implications of the study and my study objectives. In Chapters 1, 2 & 3, I investigate how selection pressures, i.e., nest predation and parasitism by haematozoa, affect bird assemblages. I used artificial nest experiments to assess nest predation rates in Chapters 1 & 2, and my...

Thesis (M.Sc. Agriculture (Pasture Science)) -- University of Limpopo, 2020 / Bush encroachment is a major problem in arid and semi-arid savannas characterized by a grass layer interspersed with a shrub stratum. Land cover change as a result of rapid proliferation of woody species in previously open rangelands alters herbaceous species and impacts soil properties. So far, little is known about the threshold at which woody plant density and cover affects herbaceous cover and the underlying mechanisms driving bush encroachment in arid and semi-arid rangelands are still debated. The objectives of this dissertation were to (1) to assess woody species composition and structure along an encroachment gradient and to explore the relationship between woody vegetation and herbaceous vegetation. (2) To determine the effect of increasing tree density and cover on grass species richness, diversity, evenness and selected soil nutrients in a bush encroached rangeland. In order to address these objectives, a semi-arid rangeland was demarcated into three encroachment gradients spanning from open to intermediate and intensive. Within each encroachment gradient six plots of 10 m x 10 m were randomly selected, whereby woody and herbaceous vegetation were assessed and soil properties determined. A discernible increase in woody species diversity and evenness was found along the transition from open to intensive bush encroached rangeland. Leguminous woody species Vachellia spp. and Dichrostachys cinerea were dominant along the bush encroachment gradient. Tree height was found to be positively correlated with long crown diameter (LCD) and short crown diameter (SCD). Furthermore, increasing tree density resulted in a 53% decline in grass species richness (GR). A decline in GR mirrored an increase in the composition of the decreaser species Panicum maximum (90%). Increasing woody plant density and cover also increased macro-nutrients; total carbon, nitrogen, phosphorus, exchangeable calcium and magnesium by 21%-159% in the shallow rangeland soils. Such quantitative information will assist rangeland managers to better understand the effects of varying bush encroachment intensities on herbaceous species composition, richness and soil properties in semi-arid savanna rangelands.

Homeotherms and many poikilotherms display a positive relationship between body size and latitude, but this has rarely been investigated in microscopic animals. We analysed all published records of marine Tardigrada to address whether microscopic marine invertebrates have similar ecogeographical patterns to macroscopic animals. The data were analysed using spatially explicit generalized least squares models and linear models. We looked for latitudinal patterns in body size and species richness, testing for sampling bias and phylogenetic constraints. No latitudinal pattern was detected for species richness, and sampling bias was the strongest correlate of species richness. A hump-shaped increase in median body size with latitude was found, and the effect remained significant for the Northern Hemisphere but not for the Southern. The most significant effect supporting the latitudinal gradient was on minimum body size, with smaller species disappearing at higher latitudes. Our results suggest that biogeographical signals were observed for body size, albeit difficult to detect in poorly studied groups because of swamping from biased sampling effort and from low sample size. We did not find a significant correlation with the latitudinal pattern of body size and ecologically relevant net primary productivity.

An intensive sampling of all ant species encountered on 6 Hawaiian Islands: Big Island, Maui, Oahu, Kauai, Molokai, and Lanai took place between 1988 and 1996. Species presence and absence was recorded at each site. Using remote sensing, variables were added insitu and used throughout my analysis. Species accumulation curves suggest that sampling was comprehensive. There is a significant trend between island area and species richness which validates the Theory of Island Biogeography for invasive species. Islands were found to be significantly nested by area, order, and tourism. Cluster analysis shows a link between elevation, land-use and island, and species presence. Predictive models can be built to predict spread of particular ant species as they continue toward equilibrium.

Svenska våtmarker har under flera hundra år dikats ut till förmån för odling av grödor och virkesproduktion. Idag ser verkligheten annorlunda ut och till förmån för klimatet satsar svenska staten nu pengar på att plugga igen diken och återställa dessa numera uttorkade våtmarker. Att huvudsyftet är minskade utsläpp av växthusgaser hindrar dock varken flora eller fauna från att utnyttja dessa nya habitat. Då hotet mot biodiversiteten i världen enligt forskningen är lika allvarligt som klimatförändringarna är det av intresse att veta hur åtgärder för att minska utsläpp av växthusgaser även påverkar artrikedomen lokalt och regionalt. Detta är en studie som utvärderar insektsfaunan på återställda våtmarker och om det går att urskilja några naturvärden baserat på vilka arter som hittats. Mellan 8 augusti och 8 september 2022 användes tre inventeringsmetoder på fyra skogslokaler och tre återställda våtmarker. Lokalerna som stod klara år 2021 är Skogsstyrelsens pilotprojekt för återvätningar. Resultatet visade att även om inga naturvårdsarter hittades, bidrar klimatgynnande återvätning av skogsmark till en ökad biodiversitet redan på kort sikt. Totalt inventerades individer av 35 olika arter och 71% fler arter hittades i våtmarkerna än i skogarna. Sex fynd var arter som specifikt föredrar våtmarker och hittades i lokalerna med öppen vattenspegel, övriga arter i våtmarkerna var generalister. Då många faktorer kan påverka olika arters migration är långsiktig övervakning eftersträvansvärt. Den här studien ger en chans för framtida uppföljning av våtmarkernas utveckling och arters etablering. Vidare en möjlighet att anpassa framtida återvätningar för att minimera utsläpp av växthusgaser och samtidigt maximera biodiversiteten. / Swedish wetlands have been drained by ditching for several hundreds of years in favour for forestry and agriculture. Today, the reality looks different, and due to the climate change the Swedish government is now investing money to plug ditches and restore these now dried-up wetlands. The main purpose is to reduce greenhouse gas emissions, but neither flora nor fauna are prevented from utilizing these new habitats. According to research, the threat to global biodiversity is as serious as climate change, it is of interest to know how measures to reduce greenhouse gas emssions also affect local and regional species richness. This is a study that evaluates the insect fauna in restored wetlands and wether any natural values can be discerned based on the species found. Between August 8 and September 8 2022, three sampling methods were used in four forest locations and three restored wetlands. The wetlands which were completed in 2021 are the Swedish Forest Agency´s pilot projects for rewetting. The results showed that even if no conservation species were found, climate-beneficial rewetting of forest land contributes to increased biodiversity in the short term. In total, individuals from 35 different species were surveyed and 71% more species were found in the wetlands than in the forests. Six findings were species that specifically prefer wetlands and were found in locations with open water surfaces, all other species were generalists. As many factors can influence the migration of different species, long-term monitoring is desirable. This study provides an opportunity for future follow-up of the development of wetlands and the establishment of species. Furthermore, an opportunity to adapt future rewetting to both minimize greenhouse gas emissions and at the same time maximize biodiversity.

In this thesis, the impact of conservation banking on biodiversity is assessed by examining the bird species richness in U.S. counties that have implemented the policy. Conservation banking is a market-based instrument designed for developers who need to comply with the Endangered Species Act for the negative environmental impacts that their projects have made. Conservation banking aims to “protect and recover imperilled species and the ecosystems upon which they depend” (USFWS 2013, p. 1). In this thesis, a staggered difference-in-difference with differential timing by Goodman-Bacon (2018) and further developed by Callaway and Sant’Anna (2021) is used to estimate the effect of conservation banks on biodiversity. Data for biodiversity, bird species richness are collected from U.S. Geological Survey's data from the North American Breeding Bird Survey (BBS). Information on conservation banks is gathered from the Regulatory In-lieu fee and Bank Information Tracking System (RIBITS). This thesis focuses on 107 conservation banks in 53 counties in the U.S. established between 2005 and 2016. The main results from this study indicate a positive impact of the introduction of conservation banks, with an increase in biodiversity of 4,1%. Consequently, this confirms the positive effect of the policy intervention. Despite these results, it is vital to consider caution regarding this market-based instrument. Market-based instruments that commodify elements of nature into the market are a new frontier in capitalist expansion. This approach may exclude areas from the natural evolutionary selection process, leading to potential long-term ecological imbalances. Current payment structures in conservation banking can lead to misallocation of taxpayers’ money at the same time as biodiversity outcomes are not optimized. Therefore, the most fundamental recommendation for this policy is to change to outcome-based payments.

Understanding relationships between large herbivores and plant species diversity in dynamic riparian zones, and more specifically sodic zones, is critical to biodiversity conservation. Sodic patches form an integral part of savanna ecosystems because of the ecosystem services and functions they provide, i.e. accumulation of nutrients, provision of open spaces for predator vigilance and formation of wet season wallowing points. Furthermore, these key resource areas sustain body condition for dry season survival and support reproduction through nutritional benefits, making them „nutrient hotspots.‟ The Nkuhlu research exclosures in the Kruger National Park (KNP) provide a unique opportunity to investigate spatial and temporal heterogeneity patterns within riparian zones, and how these patterns are affected by fire and herbivory. A monitoring project was initiated to answer questions pertaining to the dynamics of the herbaceous layer and was aimed at determining (a) whether there exists meaningful variance in herbaceous plant species richness and diversity across different treatments of fire and herbivory in the ecologically sensitive sodic zone, (b) if temporal shifts in plant species composition and diversity occurs, (c) whether an increase in herbaceous biomass, an artifact of herbivory and fire exclusion, suppresses herbaceous plant species diversity and richness, and (d) whether there exists a significant relationship between herbaceous biomass and species richness/diversity. The Nkuhlu exclosures consist of three herbivory treatments, each divided into a fire and no-fire treatment, hence six treatment combinations overall. Herbivory treatments consisted of, (1) a partially fenced area designed to specifically exclude elephants (giraffes are also excluded due to body size), (2) an open, unfenced area and (3) a fully fenced area, designed to exclude all herbivores larger than a hare. Herbaceous vegetation was sampled in two 1 m2 circular sub-plots in the eastern and western corners of each of the 82 fixed plots. Biomass of each plot was estimated with a Disc Pasture Meter (DPM) by sampling ten points diagonally within each plot. DPM-readings were converted to kg/ha according to latest conversions for the Lowveld Savanna. Species richness and biomass showed significant variance across treatments for the 2010 dataset, whereas no significant variation in herbaceous species diversity was perceived. Combined treatment of fire absence and herbivore presence contributed to higher forb species richness in the sodic zone. Biomass was significantly higher in fully fenced areas where herbivores were excluded, opposed to the open and partially fenced areas. Although no significant variation was recorded for diversity across treatments, lowest diversity was recorded in the absence of all herbivores, especially in combination with fire treatment. After nine years of herbivory exclusion, diversity of herbaceous species varied significantly. Herbaceous species composition changed over time in areas exposed to herbivory, while composition of fully fenced treatments did not reveal change. A hump-shaped relationship exists between herbaceous species richness/diversity and field biomass, at least for areas with biomass levels not exceeding 2500 kg/ha. Herbivores are therefore considered essential in sustaining herbaceous plant species richness and system heterogeneity in the sodic zone, since herbaceous species richness/diversity was higher in herbivore presence and herbaceous species composition changed over time in areas exposed to herbivory. Although statistically non-significant, fire seems to suppress species richness. Conservation implications: This study could be used as framework to advance and develop sciencebased management strategies for, at least, the sodic zones of the KNP. Research in these exclosures contributes to our understanding of these landscapes and benefit ecosystem conservation planning. It also provides valuable long-term data for key ecological processes. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Understanding relationships between large herbivores and plant species diversity in dynamic riparian zones, and more specifically sodic zones, is critical to biodiversity conservation. Sodic patches form an integral part of savanna ecosystems because of the ecosystem services and functions they provide, i.e. accumulation of nutrients, provision of open spaces for predator vigilance and formation of wet season wallowing points. Furthermore, these key resource areas sustain body condition for dry season survival and support reproduction through nutritional benefits, making them „nutrient hotspots.‟ The Nkuhlu research exclosures in the Kruger National Park (KNP) provide a unique opportunity to investigate spatial and temporal heterogeneity patterns within riparian zones, and how these patterns are affected by fire and herbivory. A monitoring project was initiated to answer questions pertaining to the dynamics of the herbaceous layer and was aimed at determining (a) whether there exists meaningful variance in herbaceous plant species richness and diversity across different treatments of fire and herbivory in the ecologically sensitive sodic zone, (b) if temporal shifts in plant species composition and diversity occurs, (c) whether an increase in herbaceous biomass, an artifact of herbivory and fire exclusion, suppresses herbaceous plant species diversity and richness, and (d) whether there exists a significant relationship between herbaceous biomass and species richness/diversity. The Nkuhlu exclosures consist of three herbivory treatments, each divided into a fire and no-fire treatment, hence six treatment combinations overall. Herbivory treatments consisted of, (1) a partially fenced area designed to specifically exclude elephants (giraffes are also excluded due to body size), (2) an open, unfenced area and (3) a fully fenced area, designed to exclude all herbivores larger than a hare. Herbaceous vegetation was sampled in two 1 m2 circular sub-plots in the eastern and western corners of each of the 82 fixed plots. Biomass of each plot was estimated with a Disc Pasture Meter (DPM) by sampling ten points diagonally within each plot. DPM-readings were converted to kg/ha according to latest conversions for the Lowveld Savanna. Species richness and biomass showed significant variance across treatments for the 2010 dataset, whereas no significant variation in herbaceous species diversity was perceived. Combined treatment of fire absence and herbivore presence contributed to higher forb species richness in the sodic zone. Biomass was significantly higher in fully fenced areas where herbivores were excluded, opposed to the open and partially fenced areas. Although no significant variation was recorded for diversity across treatments, lowest diversity was recorded in the absence of all herbivores, especially in combination with fire treatment. After nine years of herbivory exclusion, diversity of herbaceous species varied significantly. Herbaceous species composition changed over time in areas exposed to herbivory, while composition of fully fenced treatments did not reveal change. A hump-shaped relationship exists between herbaceous species richness/diversity and field biomass, at least for areas with biomass levels not exceeding 2500 kg/ha. Herbivores are therefore considered essential in sustaining herbaceous plant species richness and system heterogeneity in the sodic zone, since herbaceous species richness/diversity was higher in herbivore presence and herbaceous species composition changed over time in areas exposed to herbivory. Although statistically non-significant, fire seems to suppress species richness. Conservation implications: This study could be used as framework to advance and develop sciencebased management strategies for, at least, the sodic zones of the KNP. Research in these exclosures contributes to our understanding of these landscapes and benefit ecosystem conservation planning. It also provides valuable long-term data for key ecological processes. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014