Global ETD Search

591	The impact of selective beech (Nothofagus spp.) harvest on litter-dwelling invertebrates and the process of litter decomposition Evans, Alison January 1999 (has links) Minimising the potential impact of forest management requires an understanding of the key elements that maintain forest diversity and its role in ecological processes. Invertebrates are the most diverse of all biota and play important roles in maintaining forest processes. However, little is known about invertebrates in New Zealand's beech forests or the degree to which selective beech harvest might impact on their diversity and ability to carry out ecosystem processes. Studying ecosystem responses to disturbance is considered vital for understanding how ecosystems are maintained. One of the main objectives of this research was to assess whether litter-dwelling invertebrates were susceptible to the impacts of selective harvest and, if so, whether they could be used as indicators of forest health. Changes in invertebrate diversity could have important implications for nutrient cycling and primary production in forests. Litter-dwelling invertebrates contribute to the process of decomposition by increasing the surface area of the leaves, mixing soil organic matter and by infecting leaf particles with soil microbes. This investigation into the function of invertebrates in beech forest was carried out in the context of ecological theories which relate diversity to ecosystem stability and resilience. A replicated study was established in Maruia State Forest (South Island, New Zealand) to assess the potential biotic and abiotic impacts of sustainable beech harvest. Litter-dwelling invertebrates and environmental factors were monitored during 1997, before harvest, to determine how much variability there was between study sites. Specifically, litter pH, light intensity, litter fall, litter temperature, moisture as well as invertebrate abundance and diversity were compared before and after selective harvest. On 17 January 1998, two to three trees were selectively harvested from three of the nine study sites. On 15 February 1998 a similar number of trees were winched over or felled manually to create artificial windthrow sites. The remaining three undisturbed sites were used as controls. Invertebrates belonging to the detritivore guild were assessed from litter samples and a series of litter-bags containing pre-weighed leaf litter which were placed in each of the sites to assess rates of litter decomposition. Millipedes (Diplopoda: Polyzoniidae, Schedotrigonidae, Dalodesmidae, Habrodesmidae, Sphaerotheridae), earthworms (Oligochaeta: Annelida), tipulid larvae (Diptera: Tipulidae), weevils (Coleoptera: Curculionidae), moth larvae (Lepidoptera: Oecophoridae, Tortricidae and Psychidae), slaters (Isopoda: Styloniscidae), Oribatid mites (Acarina: Cryptostigmata) and landhoppers (Crustacea: Amphipoda) were extracted from the litter-bags and their abundance and diversity was compared between the three treatments. Weight loss from the litter-bags and the carbon and nitrogen content of litter were used to measure the rate of decomposition in each treatment. An additional study investigated whether exclusion of invertebrates from leaf litter resulted in reduced rates of decomposition. The results indicated that there was an increase in light intensity and a small increase in temperature following selective harvest and artificial windthrow. There was no significant difference in litter moisture or the amount of litter fall between the treatments. Invertebrate abundances were significantly affected by season but did not appear to be affected by selective harvest or artificial windthrow. The diversity of invertebrates remained relatively constant throughout the year, as did the rate of decomposition. When invertebrates were excluded from the leaf litter there was no consequential effect on the rate of litter decomposition. This suggests that there may be compensatory mechanisms taking place between the trophic levels of the food web to maintain processes and that direct links between invertebrates and decomposition are relatively weak. In conclusion, it appears that the effects of selective beech harvest on forest-floor processes were minimal and are comparable to those created by natural windthrow disturbance. It also appears that macroclimatic effects such as seasonal climatic effects have a large effect on forest biota. As none of the invertebrates studied appeared to be detrimentally affected by selective harvest and as there was no direct link demonstrated with decomposition, it was considered inappropriate to advocate the use of this group of invertebrates as indicators of sustainable forest management. The results from this study provide information which may help inform decisions on the future management of diversity in beech forest ecosystems. Nothofagus beech forest sustainability diversity decomposition ecosystem processes selective harvest disturbance invertebrates detritivores litter-bags indicator species taxa
592	Ecological and Edaphic Correlations of Soil Invertebrate Community Structure in Dry Upland Forests of Eastern Africa Mauritsson, Karl January 2018 (has links) Natural forests are characterised by great vegetation diversity and create habitats for a major part of Earth’s terrestrial organisms. Plantation forests, which are mainly composed of a few genera of fast-growing trees, constitute an increasing fraction of global forests, but they only partly compensate for loss of area, habitat and ecological functions in natural forests. Plantation forests established near natural forests can be expected to serve as buffers, but they seem to be relatively poor in invertebrate species and it is not clear why. This bachelor’s degree project aimed at establishing the ecological and edaphic factors that correlate with soil invertebrate diversity in dry upland forests and surrounding plantation forests in eastern Africa. Some aspects of the above-ground vegetation heterogeneity were investigated since this was assumed to influence the heterogeneity of the soil environment, which is considered as critical for soil biodiversity. The obtained knowledge may be valuable in conservation activities in East African forests, which are threatened by destruction, fragmentation and exotic species. The study area was Karura Forest, a dry upland forest in Nairobi, Kenya. Three different sites were investigated; a natural forest site characterized by the indigenous tree species Brachylaena huillensis and Croton megalocarpus, and two different plantation forest sites, characterized by the exotic species Cupressus lusitanica and Eucalyptus paniculata, respectively. For each forest type, six plots were visited. Soil invertebrates were extracted from collected soil and litter samples by sieving and Berlese-Tullgren funnels. The invertebrates were identified, and the taxonomic diversity calculated at the order level. The ecological and edaphic factors, measured or calculated for each plot, were tree species diversity, ratio of exotic tree species, vertical structure of trees, vegetation cover, vegetation density, litter quality, soil pH, soil temperature and soil moisture. One-way ANOVA was used to compare soil invertebrate diversity and other variables between different forest types. Akaike’s Information Criterion and Multiple Linear Regression were used to establish linear models with variables that could explain measured variations of the diversity. There was some evidence for higher soil invertebrate diversity in natural forests than in surrounding plantation forests. The abundance of soil invertebrates was also clearly higher in natural forests, which indicates that natural forests are more important than plantation forests for conservation of soil invertebrate populations. Soil invertebrate diversity (in terms of number of orders present) was found to be influenced by forest type and litter quality. The diversity was higher at places with high amounts of coarse litter, which here is considered as more heterogenous than fine litter. The dependence on forest type was partly a consequence of differences in soil pH since Eucalyptus trees lower soil pH and thereby also soil biodiversity. No relation to heterogeneity of above-ground vegetation was found. For future conservation activities in Karura Forest Reserve it is recommended to continue removing exotic plant species and replanting indigenous trees, to prioritize the removal of Eucalyptus trees before Cypress trees, to only remove a few trees at a time and to establish ground vegetation when doing so. Natural forests plantation forests Brachylaena-Croton forest Cupressus lusitanica Eucalyptus paniculata exotic species biodiversity soil invertebrates Berlese-Tullgren funnel vertical structure vegetation cover vegetation density litter quality edaphic factors soil pH soil temperature soil moisture ANOVA Multiple Linear Regression Akaike’s Information Criterion Ecology Ekologi
593	An evaluation of macroinvertebrate-based biomonitoring and ecotoxicological assessments of deteriorating environmental water quality in the Swartkops River, South Africa Odume, Oghenekaro Nelson January 2014 (has links) Freshwater resources are increasingly subject to pollution because of escalating human population growth, accompanied by urbanisation, industrialisation, and the increased demand for food. Consequently, freshwater quality, and aquatic ecosystem structure and function have been severely impaired. The Swartkops River, which drains an urbanised and industrialised catchment in the Eastern Cape of South Africa, is no exception. An integrated environmental water quality (EWQ) approach is needed to measure the impacts of deteriorating water quality on its aquatic ecosystem structure and function to sustain these vital ecosystem-attributes. In this study, an integrated EWQ approach, which included i) analysis of water physico-chemical variables; ii) macroinvertebrate-based family-level taxonomic- and traits-based community analysis; iii) Chironomidae species-level taxonomic- and traits-based community analysis; iv) Chironomidae deformity-based sub-lethal analysis; and v) experimental investigation of long-term wastewater effluent effects, using model stream ecosystems, were applied to investigate environmental water quality in the Swartkops River. One upstream reference site and three downstream sites in the Swartkops River were monitored over a period of three years (August 2009 – September 2012). The family-level taxonomic community responses based on the South African Scoring System version 5 (SASS5) and a newly developed Swartkops multimetric index indicated very poor river health conditions for the three downstream sites, compared with the good condition of the upstream site. The Chironomidae species-level responses in the three downstream sites provided evidence of differences in biotic impairments, which were not evident with the family-level taxonomic data at these sites, thus highlighting the importance of species identification in freshwater biomonitoring. The family-level traits-based approach (TBA) showed that macroinvertebrates with gills and lungs were more abundant at the upstream site, decreasing markedly at the downstream sites. The relative abundance of macroinvertebrates relying on aerial and tegument respiration increased at the downstream sites compared with the upstream sites. The results of the family-level TBA highlighted the inextricable link between the traits-based approach (TBA) and taxonomic identification, clearly showing that the TBA is additional to, and not an alternative to, taxonomic recognition because important traits, e.g. reproductive cannot be used at a coarse taxonomic identification. A novel chironomid species traits-based functional strategies approach developed in this study, based on species combining similar sets of traits, proved sensitive in diagnosing the main abiotic water physico-chemical stressors. The functional traits responded predictably to deteriorating water quality and provided an adaptive and mechanistic basis for interpreting chironomid species occurrences at the four sampling sites, providing insight into why certain chironomid species occurred at one site but not at the other. Chironomid deformities provided evidence of sub-lethal in-stream biological response to deteriorating water quality. A newly developed deformity-based extended toxic score index proved sensitive, enabling the discrimination of the sampling sites, indicating that a biomonitoring tool based on sub-lethal effects could be used to assess the effects of deteriorating water quality before it reached lethal levels. Empirical evidence based on the taxonomic, traits and sub-lethal responses suggested that the changes in macroinvertebrate community structure were caused chiefly by the discharge of wastewater effluents into the river. This was supported by the model-stream ecosystem results indicating significant effects of effluents on the macroinvertebrate community structure, similar to the observed in-stream responses. The model stream results indicated that improved physico-chemical effluent quality compliance after 50% effluent dilution did not significantly reduce the effects of the effluent on the macroinvertebrate communities, showing that ecologically-based methods rather than physico-chemical measures alone are necessary to assess effluent quality. Finally, the results of the multi-criteria approach were integrated to propose tools to manage environmental water quality in the Swartkops River, and the benefits of the study were highlighted in the context of biomonitoring in South Africa.
594	Dynamique des masses d'eaux côtières libanaises soumises à l'impact d'un fleuve. / Dynamics of Lebanese coastal waters subjected to the impact of a river Ghsoub, Myriam 27 September 2019 (has links) Le but principal de cette étude est de comprendre le fonctionnement de la zone interface, continuum terre-mer au Liban. Suite à l’anthropisation spécifiquement la construction des barrages, les apports du fleuve vers la mer en termes de quantité et qualité, sont modifiés de nos jours. Le fleuve Ibrahim, ayant le débit le plus important parmi les fleuves libanais, interrompu par trois barrages, a été choisi comme étude de cas représentant les fleuves côtiers libanais. Les différents paramètres retenus ont permis de dégager des résultats intéressants. Au niveau de l’eau de surface marine le panache fluvial est décelé par l’étude des paramètres hydrologiques des masses d’eaux superficielles. Les résultats montrent aussi que l’apport fluviatile est le contributeur principal en nutriments au niveau de la région côtière durant la saison humide, élucidé par les teneurs en nitrates et silice dissoute. D’autre part, le transfert des particules de la zone côtière vers le large, à travers la pente continentale, se fait par l’intermédiaire de couches néphéloïdes.L’origine des sédiments et de leurs constituants est mise en relief en analysant plusieurs paramètres sédimentaires. La combinaison des paramètres granulométriques et géochimiques organiques et inorganiques et l’application des tests statistiques a permis de distinguer entre deux environnements de dépôt. (1) Les environnements littoraux (≤ 30 m) ou zone de « bypass » où le sable fin et la matière organique autochtone dominent. (2) Les environnements profonds (≥ 60 m) ou zones de dépôts où la fraction fine et la matière organique allochtone dominent.Sur l’ensemble du suivi l’état chimique de l’eau du fleuve au niveau des deux stations échantillonnées, déduit des teneurs en nutriments et macrofaune benthique, est considéré comme bon à très bon d’après les normes internationales Finalement, l’analyse des éléments traces métalliques confirme la faible contribution anthropique dans les stations marines et fluviatiles échantillonnées malgré la densité de population croissante au niveau de la région côtière Libanaise. / The main purpose of this study is to understand the functioning of the coastal zone, land-sea continuum in Lebanon. Following the construction of dams, the contributions of the river towards the sea in terms of quantity and quality, are modified nowadays. The Ibrahim river, having the highest flow among the Lebanese rivers, interrupted by three dams, was chosen as a case study representing the Lebanese coastal rivers. The various parameters retained made it possible to obtain interesting results. At sea surface water level, the river plume is detected by studying the hydrological parameters of surface water.The results also show that the river is the main nutrient contributor in the coastal region during the wet season, elucidated by the nitrate and dissolved silica contents. On the other hand, the transfer of particles from the coastal zone to the open sea, across the continental slope, takes place through the nepheloid layers.The origin of sediments and their constituents is highlighted by analyzing several sediment parameters. The combination of organic and inorganic particle size and geochemical parameters and the application of statistical tests made it possible to distinguish between two deposition environments. (1) Coastal environments (≤ 30 m) or “bypass” area where fine sand and autochtonous organic matter dominate. (2) Deep environments (≥ 60 m) or deposit areas where the fine fraction and allochthonous organic matter dominate.The ecological state of the river water at the two sampled stations, deduced from the contents of nutrients and benthic macrofauna, is considered good to very good according to international standards. Finally, the analysis of metallic trace elements confirms the low anthropogenic contribution in the marine and river stations despite the increasing density of the population in the Lebanese coastal region. Méditerranée orientale Liban Fleuve Ibrahim Zone côtière Paramètres hydrologiques Granulométrie Matière organique Éléments traces métalliques Terres rares Macro invertébrés-benthiques Eastern Mediterranean Lebanon Ibrahim River Coastal zone Hydrological parameters Granulometry Organic matter Trace metals Rare earth elements Benthic macro invertebrates 551.46
595	Geochemical Analysis of the Environmental Phases of La Barra de Santiago Estuary, El Salvador AYO-BALI, ABIODUN Emmauel 20 September 2019 (has links) No description available. Agricultural Chemicals Aquatic Sciences Biogeochemistry Biological Oceanography Chemical Oceanography Earth Ecology Environmental Geology Environmental Health Environmental Science Environmental Studies Geochemistry Geological Geology Marine Geology Natural Resource Management Barra de Santiago estuary Geochemical analysis environmental phases macro invertebrates El Salvador Sugarcane agrochemicals fertilizers heavy metals pollution indices sediment quality assessment
596	Factors Affecting Invertebrate and Fish Communities in Coastal Wetlands of the Great Lakes Kapusinski, Douglas John 19 November 2012 (has links) No description available. Animal Sciences Aquatic Sciences Biology Ecology Entomology Environmental Science Environmental Studies Freshwater Ecology Organismal Biology Zoology benthic invertebrates Lake Erie marsh Great Lakes Coastal Wetland shorebirds common carp Cyprinus carpio Dreissenidae Driessena polymorpha Unionidae Quadrula quadrula Chironomidae Oligochaeta Sphaeriidae Non-metric Multidimensional Scaling
597	Microbial sulfate reduction in the tissue of the cold-water sponge Geodia barretti (Tetractinellida, Demospongiea) / Mikrobielle Sulfatreduktion im Gewebe des Kaltwasserschwammes Geodia barretti (Tetractinellida, Demospongiae) Hoffmann, Friederike 06 May 2003 (has links) No description available. 550 Geowissenschaften Mathematics and Computer Science Porifera Invertebraten marin Norwegische See boreal Histologie Fluroeszenz in situ Hybridisierung FISH Einbetten von Gewebe Heilung Regeneration Reproduktion Sulfatreduktion sulfatreduzierende Bakterien Invertebrat-Bakterien-Symbiose Biogeochemie Schwefelkreislauf Sulfatreduktionsrate Mikroelektrode porifera invertebrates marine Norwegian Sea boreal histology fluorescence in situ hybridization FISH tissue embedding cicatrisation regeneration reproduction sulfate reduction sulfate reducing bacteria invertebrate-microbe symbiosis biogeochemistry sulfur cycle sulfate reduction rate microelectrode 42.21 42.15 42.21 42.72 38.19 58.30 VU WB WH WN WR WY
598	Birds, bats and arthropods in tropical agroforestry landscapes: Functional diversity, multitrophic interactions and crop yield Maas, Bea 20 November 2013 (has links) No description available. 630 birds bats arthropods multitrophic interactions agroforestry tropical landscape forest margin landscape functional diversity crop yield exclosure experiments experimental exclusion arthropod suppression avian predation ecosystem services mist netting point counts artificial plasticine caterpillar dummy experiment biological control monitoring mapping Lemon-bellied White-eye Grosbeak Starling Zosterops chloris Scissiostrum dubium Theobroma cacao cacao agroforestry cacao diseases cacao harvest cacao pests flying vertebrates aerial insectivores volant vertebrates logging breeding colony flower herbivory mesopredator release predatory insects ants spiders aphids Lepidoptera Coleoptera Lepidopteran larvae sustainable agriculture sustainable agroforestry management implications management recommendations applied managament extensive land use management landscape management conservation biodiversity-friendly dbh distance to forest forest proximity habitat conversion herbivory Indonesia insectivorous bats insectivorous birds invertebrates Central Sulawesi Napu valley leaf gleaning leaf herbivory pests insects phytophagous insects plant productivity remnant forest trees shade tree managament South-east Asia Paleotropics tropical landscape tree height landscape gradient local shade management Cacao Pod Borer Cherelle Wilt fruit abortion Helopeltis sulawesi deforestation habitat fragmentation land use intensification forest margin species critical decline predation experiment species-specific functions Southeast Asia biodiversity conservation mesopredators food security human welfare human well-being poverty alleviation poverty reduction smallholder cacao smallholder plantation cacao farmers sustainable cacao management landscape perspective landscape scale large scale field experiment long term field experiment human wellbeing economic importance economic value valuation ecosystem services landscape matrix yield quality yield quantity fruit productivity species identity species diversity species richness ecosystem functioning pesticide use chemical compounds complex food web tritrophic interactions wildlife-friendly rural livelihoods endangered bird species endangered bat species endemic endemic birds endemic bats beneficial impact IUCN Lore Lindu National Park bioindicator indicator species forest margin agricultural habitat agroforestry systems population density predation activity species activity cacao flower cacao pod Orthoptera linear mixed effect models Tukey Post Hoc Test AICc model selection generalized least squares restricted maximum likelihood model simplification species richness estimator species accumulation linear mixed-effects models Likelihood Ratio Test Maximum Likelihood nocturnal insects diurnal arthropods nocturnal arthropods diurnal insects landscape context Land- und Forstwirtschaft (PPN621302791)

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