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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Species richness in riparian vegetation, a pilot study in Halmstad

Castellano Jorge, Aurora January 2014 (has links)
The riparian forests are hotspots of biodiversity and serve important roles in maintainingthe water quality. The study and understanding of this ecosystem is basic to know how theriparian zones respond to the threat and the changes produced by the urbanization. Theobjective of this pilot study was to know the species richness and check the status of theriparian vegetation along two different rivers in Halmstad, Nissan and Fylleån. The studywas focus on the status of trees at both rivers to see if the proximity of the city has anyimpact on the biodiversity. In total 9 different species were found, nevertheless only 3 ofthese species were founded on both localizations: Quercus robur, Betula pendula and Pinussylvestris. The Shannon Index showed a higher biodiversity on Nissan riparian zones, whichis the river that present the urban component. The urban area is the one that presentshigher level of biodiversity, tree species and number of individuals but there are notenough to be in a good standard. The result just show that the urban area is in a bettercondition that the natural one. The institutional efforts should be focusing on preserveboth environments with special attention to the natural environment.
2

How has woody vegetation changed in north-east Namibia in response to land use, climate and fire?

Eastment, Conor 14 September 2020 (has links)
Bush encroachment or the thickening of woody vegetation is a phenomenon occurring throughout savannas, which tends to be more pronounced in small protected areas. The consequences of bush encroachment are often negative for the conservation of biodiversity, for the promotion of tourism and the prevention of wildfires. Hence, effective monitoring of woody vegetation and the factors which influence its spread are essential. This is particularly the case for protected areas such as that of Bwabwata National Park (BNP) in north-east Namibia. With a complex land use history and different fire management approaches being adopted throughout the area, the effect of fire on woody vegetation in BNP is currently poorly understood. This study used a 20-year-old repeat photography monitoring project and satellite-based remote sensing products to explore woody cover dynamics in BNP. Results revealed that woody cover has increased by 13% since 1999 in BNP. Furthermore, the results show differences in the structure of woody vegetation. Repeated late dry season fires in the west of the park have driven an increasing dominance of 3m in eastern sections of the park. This influence of different fire regimes spatially across BNP, suggests that local fire management is a significant determinant of woody vegetation change. Woody vegetation change differs spatially across BNP due to frequent late dry season fires prevailing in the west and less frequent earlier season fires occurring in the east. Therefore, in order to reduce the mortality of woody species and conserve heterogenous height structure in the west, a reduction of frequent late dry season fires is required. Early dry season fires are shown to reduce the rate of increasing total woody cover change and, therefore, this fire management strategy arguably contributes towards the reduction of wildfire risk, conservation of biodiversity and promotion of tourism.
3

Effects of Woody Vegetation Removal on Soil Water Dynamics in a South Texas Shrubland

Mattox, April Marie 16 December 2013 (has links)
Ecosystem changes from grassland to shrubland in the Rio Grande Plains are thought to have negative effects on the hydrology of the region. The increase in woody plants, known as woody encroachment, may alter the amount of water moving beyond the root zone of plants. Water moving beyond the root zone is referred to as deep drainage, and has potential to become aquifer recharge. A vegetation manipulation project was designed to understand the effects of woody vegetation removal on soil water dynamics in the recharge zone of the Carrizo-Wilcox aquifer of south Texas. The primary objective of the project was to determine the potential to increase groundwater recharge through woody vegetation removal. To understand the effects of vegetation removal on various soil textures we studied changes in soil water, rooting depth, and the role of water redistribution by woody vegetation. Woody vegetation was removed using common methods of cut-stump and roller chop across three soil types. Soil water contents and changes were measured using neutron moisture meter to a depth of 180 cm. Average rooting depth was determined across three soil types. Soil and stem water stable isotopes were used to understand soil water movement. Rooting depth was determined to between 140 and 160 cm for all soil textures. Soil water content and changes were analyzed at three depth increments: 0-60, 60-120 and 120-180 cm. ANOVA analysis showed that there was no treatment response in average soil profile water in the sandy or sandy loam soils. There was a significant decrease in soil profile water for clay loam soil in response to roller chopping. Changes in soil profile water were the greatest in the sandy roller chopped soils. Below 120 cm, three months had significant differences in change in soil water in the sandy roller chop plot. During dry conditions, Honey mesquite shifts water use to deeper in the soil profile. In clay loam soils under dry conditions there is evidence of water being moved up from below 2 m soil depth to drier shallow soils. Roller chopping in sandy soils is the vegetation removal treatment and soil type most likely to result in water moving beyond the root zone. Although treatments had significant effects on soil moisture dynamics that interacted with soil type, we did not find support for deep drainage effects over the Carrizo-Wilcox aquifer from woody vegetation removal.
4

Babrungo upės baseino reguliuotų upių vykstančių natūralizacijos procesų bei pakrančių apsaugos juostų tyrimai ir vertinimas / Research and evaluation of undergoing naturalization processes and riparian protection strips of rivers regulated in Babrungas river basin

Drungilas, Gediminas 17 June 2014 (has links)
Šiame darbe aptariama šiaurės vakarų Lietuvoje, Plungės rajono savivaldybėje, esančio Babrungo upės baseino reguliuotose upėse vykstantys natūralizacijos procesai. Reguliuotose Babrungo ir Dirnupio upės pakrantės šlaituose ir apsaugos juostose aptikta 871 vienetai sumedėjusios augalijos. Tyrimais nustatyta, kad augalija dažniausiai ir tankiausiai auga šlaito viduriniojoje dalyje. Dirnupio upės tyrinėtame 1,8 km ruože sumedėjusios augalijos plotis kairiajame šlaite Lap = 2,11 ± 0,14 m, dešiniajame šlaite Lap = 1,71 ± 0,23 m. Babrungo upės tyrinėtame 2,2 km ruože apskaičiuotas kairiajame šlaite Lap = 1,86 ± 0,44 m, o dešiniajame šlaite Lap = 1,47 ± 0,27 m. Atlikus dispersinę analizę galima teigti, kad apaugusių sumedėjusia augalija šlaitų pločių vidurkiai, esant 95 % patikimumui, esminiai nesiskiria. Babrungo ir Dirnupio upės ruožų pakrančių apsaugos juostų pločiai miškuose ir pievose atitinka, o ariamoje žemėje neatitinka aplinkosauginių reikalavimų. Ariamose žemėse visi matuoti upės pakrantės apsaugos juostos pločiai buvo ≤5,0 m. / This article is about naturalization processes that take place in the regulated rivers of Babrungas river-basin in the northwestern Lithuania, Plungė district municipality. There are 871 units of woody vegetation in the riverside slopes and protective zones of the regulated Babrungas and Dirnupis rivers. Researchers have shown that usually the vegetation is the densest in the middle part of the slope. The width of woody vegetation on the left slope of 1.8 km strip of the Dirnupis river Lap = 2.11 ± 0.14 m, on the right slope Lap = 1.71 ± 0.23 m. On the left slope of 2.2 km strip of the Babrungas river Lap = 1.86 ± 0.44 m, and on the right slope Lap = 1.47 ± 0.27 m. The dispersive analysis allows to claim that given 95% of reliability, width averages of woody vegetation on the slopes do not differ. The widths of protective coast zones of Babrungas and Dirnupis rivers are the same in the woods and meadows, but in arable land they do not meet the environmental requirements. All widths of protective coast zones of arable land were ≥ 5.0 m.
5

Zhodnocení dřevinných výsadeb prováděných při revitalizacích drobných říčních toků / The evaluation of woody plantings carried out in revitalization small streams

KELLEROVÁ, Petra January 2015 (has links)
The aim of this thesis is to evaluate the success of woody plantings carried out in order to revitalize small streams. For selected restorations was assessed dendrological composition, establishment, health and care after planting. The most common species planted in the revitalization of small streams is the alder (Alnus glutinosa), a pioneer tree species reinforcing shores, to which it was coupled with flowing water home. Sometimes forming groups with gray alder (Alnus incana) but that does not fit stagnant water and silver birch (Betula pendula). Also mountain elm (Ulmus glabra) and willow species (Salix sp.) are widely planted along streams. Locally, there were planted common ash (Fraxinus excelsior) but mostly in very poor condition, and oak (Quercus robur), sporadically rowan (Sorbus aucuparia), dogwood (Swida sanquinea) and Norway maple (Acer platanoides). A statistical evaluation shows that the biggest influence on species composition and state of health of trees has the revitalization age. Also important is the care of the vegetation in later years after planting.
6

Long-term monitoring of elephant impact on the woody vegetation in the Tembe Elephant Park, South Africa

Potgieter, Mary-Lee 21 June 2013 (has links)
The African Elephant is a key component of the savanna ecosystem. They contribute to the generation of habitat for smaller vertebrates, as well as invertebrates, by the breaking of branches or uprooting of trees. Elephants also play a role in seed dispersal, germination and sapling recruitment. All these functions are advantageous to the ecosystem if the elephant population size is acceptable for the size of the reserve and the amount of available forage. The Tembe Elephant Park covers an area of 30 013 ha and is situated in northern KwaZulu Natal. This reserve has a diversity of vegetation types and is part of the Maputaland Centre of Plant Endemism and the Maputaland-Pondoland-Albany Hotspot of Biodiversity. Elephant numbers in the park are currently high and the elephant population is still increasing. This is threatening, especially to the endemic Sand Forest communities within the park. The extent of elephant impact in Tembe Elephant Park, South Africa, was investigated and compared to data collected six years prior to the current study. Elephant impact was determined in 44 transects within nine communities across the park. Percentage canopy removal was calculated for the woody individuals found in sites and with this data the targeted size classes and species could be identified. The preferences of elephants for specific woody species were determined by three electivity indices. Elephant utilisation in Tembe Elephant Park, as reflected by percentage canopy removal, increased since 2004 as the elephant population increased. Communities that experienced high values in 2010 of elephant utilisation were the Closed Woodland 1, Mature Sand Forest, Open Woodland 1 and the Closed Woodland 3. Not only did the actual canopy volume removed by elephant increase with approximately 57%, but the total canopy volume available for browsing decreased extensively since 2004. The size classes targeted by the elephants remained approximately the same from 2004 to 2010 although the 2010 results showed that elephant canopy removal percentage increased in the large size classes. This was expected as elephants target individuals with large stem diameters. A change in the selection for woody species by elephants was clear, but the change in species preference made future projections of canopy removal problematic. Elephants seem to utilise a species at extreme levels until the species is almost extirpated, then they move onto the next target species. This routine is evident in the results as highly preferred species in 2004, with high canopy volumes available and removed, had low canopy availability and electivity ratios in 2010, consequently the elephants moved on from these species as individuals became scarce. It was clear that the structure of individuals, populations and communities were being altered, selected species were facing extirpation and composition of communities was changed through the browsing manners of elephants. Management actions should be implemented to prevent irreversible damage to the vegetation and to conserve the woody species currently under threat. / Dissertation (MSc)--University of Pretoria, 2012. / Plant Science / MSc / Unrestricted
7

Long-term Interactive Impacts of the Invasive Shrub <i>Lonicera Maackii</i>, and White-Tailed Deer, <i>Odocoileus Virginianus</i>, on Woody Vegetation

Donoso, Marco Uriel 26 July 2022 (has links)
No description available.
8

Research and evaluation of overgrowth of regulated streams with woody vegetation / Reguliuotų upelių užaugimo sumedėjusia augalija tyrimai ir vertinimas

Barvidienė, Oksana 04 December 2009 (has links)
Issues of regulated streams naturalization were analyzed in the dissertation. Subject of the research was the streams regulated for drainage purposes in a hilly relief region of the Southeast Lithuania. Self-naturalization was researched only in plain relief. Since naturalization processes are running differently, it was decided to evaluate them in a hilly relief in the region of the Southern Lithuania. Researches of regulated streams are important due to the fact, that naturalization of regulated streams with growing woody vegetation on the slopes of a stream bed almost does not decrease its hydraulic conductivity but helps to restore regime of natural flows and restore damaged aqueous ecosystems at the same times. The main target of the research is to determine regularities of self-overgrowth of regulated streams with woody vegetation and assess influence of its distribution on bed’s hydraulic conductivity and flood dynamics. Following tasks are solved in the work: regularities of woody vegetation specie composition, frequency, density distribution, influence of woody and grass vegetation on regulated stream’s hydraulic conductivity. The dissertation is composed of introduction, five chapters, general conclusions, recommendations. Introduction describes relevance of the problem, aim of the work, tasks are introduced, scientific novelty of the work is described, presentations on scientific conferences and publications are introduced. Chapter one is dedicated for analysis of... [to full text] / Disertacijoje nagrinėjami reguliuotų upelių natūralizacijos klausimai. Tyrimo objektas yra Pietryčių Lietuvos sausinimo reikmėms reguliuoti upeliai, esantys kalvoto reljefo regione. Savaiminė natūralizacija tirta tik lyguminiame reljefe. Kadangi natūralizacijos procesai vyksta skirtingai, nuspręsta įvertinti juos kalvotame Pietryčių Lietuvos regione. Reguliuotų upelių tyrimai svarbūs tuo, kad reguliuotų upelių natūralizacija, sumedėjusiai augalijai augant ant upelio vagos šlaitų, beveik nemažina jų hidraulinio laidumo, tačiau padeda atkurti natūralių tėkmių režimą ir tuo pačiu atstatyti pažeistas vandens ekosistemas. Pagrindinis tyrimų tikslas – nustatyti reguliuotų upelių savaiminio apaugimo sumedėjusia augalija dėsningumus ir įvertinti jos pasiskirstymo įtaką vagos hidrauliniam laidumui bei potvynių dinamikai. Darbe sprendžiami šie uždaviniai: sumedėjusios augalijos rūšinės sudėties, dažnio, tankio pasiskirstymo dėsningumai, sumedėjusios ir žolinės augalijos poveikis reguliuotų upelių hidrauliniam laidumui. Disertaciją sudaro įvadas, penki skyriai, bendrosios išvados, rekomendacijos. Įvadiniame skyriuje nagrinėjamas problemos aktualumas, pateiktas darbo tikslas, uždaviniai, aprašomas mokslinis darbo naujumas, pristatomi mokslinių konferencijų pranešimai ir publikacijos. Pirmasis skyrius skirtas natūralių upelių reguliavimo tendencijoms analizuoti. Apibūdintas augalijos plitimas reguliuotuose upeliuose, jų įtaka hidrauliniam vagos laidumui. Antrajame skyriuje pateikta... [toliau žr. visą tekstą]
9

Reguliuotų upelių užaugimo sumedėjusia augalija tyrimai ir vertinimas / Research and evaluation of overgrowth of regulated streams with woody vegetation

Barvidienė, Oksana 04 December 2009 (has links)
Disertacijoje nagrinėjami reguliuotų upelių natūralizacijos klausimai. Tyrimo objektas yra Pietryčių Lietuvos sausinimo reikmėms reguliuoti upeliai, esantys kalvoto reljefo regione. Savaiminė natūralizacija tirta tik lyguminiame reljefe. Kadangi natūralizacijos procesai vyksta skirtingai, nuspręsta įvertinti juos kalvotame Pietryčių Lietuvos regione. Reguliuotų upelių tyrimai svarbūs tuo, kad reguliuotų upelių natūralizacija, sumedėjusiai augalijai augant ant upelio vagos šlaitų, beveik nemažina jų hidraulinio laidumo, tačiau padeda atkurti natūralių tėkmių režimą ir tuo pačiu atstatyti pažeistas vandens ekosistemas. Pagrindinis tyrimų tikslas – nustatyti reguliuotų upelių savaiminio apaugimo sumedėjusia augalija dėsningumus ir įvertinti jos pasiskirstymo įtaką vagos hidrauliniam laidumui bei potvynių dinamikai. Darbe sprendžiami šie uždaviniai: sumedėjusios augalijos rūšinės sudėties, dažnio, tankio pasiskirstymo dėsningumai, sumedėjusios ir žolinės augalijos poveikis reguliuotų upelių hidrauliniam laidumui. Disertaciją sudaro įvadas, penki skyriai, bendrosios išvados, rekomendacijos. Įvadiniame skyriuje nagrinėjamas problemos aktualumas, pateiktas darbo tikslas, uždaviniai, aprašomas mokslinis darbo naujumas, pristatomi mokslinių konferencijų pranešimai ir publikacijos. Pirmasis skyrius skirtas natūralių upelių reguliavimo tendencijoms analizuoti. Apibūdintas augalijos plitimas reguliuotuose upeliuose, jų įtaka hidrauliniam vagos laidumui. Antrajame skyriuje pateikta... [toliau žr. visą tekstą] / Issues of regulated streams naturalization were analyzed in the dissertation. Subject of the research was the streams regulated for drainage purposes in a hilly relief region of the Southeast Lithuania. Self-naturalization was researched only in plain relief. Since naturalization processes are running differently, it was decided to evaluate them in a hilly relief in the region of the Southern Lithuania. Researches of regulated streams are important due to the fact, that naturalization of regulated streams with growing woody vegetation on the slopes of a stream bed almost does not decrease its hydraulic conductivity but helps to restore regime of natural flows and restore damaged aqueous ecosystems at the same times. The main target of the research is to determine regularities of self-overgrowth of regulated streams with woody vegetation and assess influence of its distribution on bed’s hydraulic conductivity and flood dynamics. Following tasks are solved in the work: regularities of woody vegetation specie composition, frequency, density distribution, influence of woody and grass vegetation on regulated stream’s hydraulic conductivity. The dissertation is composed of introduction, five chapters, general conclusions, recommendations. Introduction describes relevance of the problem, aim of the work, tasks are introduced, scientific novelty of the work is described, presentations on scientific conferences and publications are introduced. Chapter one is dedicated for analysis of... [to full text]
10

Evaluación de la biodiversidad en el mosaico urbano de la ciudad de Pichilemu, Región del Libertador General Bernardo O'Higgins

Riquelme Negrete, Sebastian January 2019 (has links)
Memoria para optar al título de Geógrafo / En los últimos años la ciudad de Pichilemu ha experimentado un sostenido crecimiento físico y demográfico por influencia de la actividad turística, ocasionando una presión creciente sobre áreas de alto valor ecológico, y por ende, alteraciones en la biodiversidad local. Siguiendo la tendencia de América Latina, Chile posee un déficit de estudios de ecología urbana, motivo por el cual esta memoria contribuye evaluando la biodiversidad de avifauna y vegetación leñosa en las coberturas de suelo del mosaico urbano de Pichilemu. El levantamiento de información de biodiversidad se llevó a cabo mediante conteo de aves e inventarios florísticos entre el período estival del 2017 y el de 2018. Con esta información se calculó riqueza, abundancia, tres índices de diversidad alfa (Shannon-Wiener, Pielou y Simpson), en conjunto con los porcentajes de especies endémicas, nativas y amenazadas. Además, se analizó si la distancia entre los puntos de muestreo y los componentes de infraestructura verde diversos en Shannon influencia la distribución espacial de los valores de los parámetros de diversidad alfa. Paralelamente se clasificaron las especies de avifauna en gremios tróficos y según su grado de sensibilidad a la urbanización. Asimismo, se compararon las coberturas de suelo en función de su biodiversidad a través del test de Kruskall-Wallis y el test de Dunn. Por último, se realizó un análisis de clúster para ver la similitud entre las coberturas de suelo. Los resultados señalan un patrón bimodal en el índice de Shannon, pues existen dos grupos de coberturas de suelo que presentan los valores máximos en esta variable en Pichilemu. El primero de ellos, con los valores más altos del índice de Shannon, está compuesto por coberturas naturales tales como los humedales y cuerpos de agua, quebradas y cursos de agua, y matorral arborescente. El otro grupo, con los segundos valores más altos del índice de Shannon, está integrado por coberturas híbridas como el tejido urbano continuo y el tejido urbano discontinuo. En Pichilemu, las especies de avifauna son mayoritariamente nativas, mientras que gran parte de las especies de vegetación leñosa son exóticas, muchas de ellas siendo exóticas invasoras. A pesar de su alta diversidad, el tejido urbano continuo alberga casi todos los individuos pertenecientes a una especie urban exploiter (Passer domesticus). Al contrario, los individuos de las especies urban avoiders se concentran en coberturas diversas y poco intervenidas como los humedales y cuerpos de agua, quebradas y cursos de agua, playas, dunas y arenales, y el matorral arborescente. Al mismo tiempo, estas coberturas naturales son las que exhiben la mayor cantidad de gremios tróficos. Respecto al análisis de correlación, la distancia entre los puntos de muestreo y las coberturas correspondientes a componentes de infraestructura verde diversos en Shannon no explica totalmente la variabilidad de los parámetros de diversidad alfa. Mediante el análisis de clúster, se destacan los altos niveles de diversidad del conglomerado compuesto por los humedales y cuerpos de agua, quebradas y cursos de agua, matorral arborescente, matorral pradera, y las plantaciones, De este modo, se concluye que estas coberturas deberían ser priorizadas para las labores de restauración ecológica y conservación de la biodiversidad. / Throughout the last years, the city of Pichilemu has undergone a sharp spatial and demographic growth influenced partly by tourist activity, which it caused an increasing pressure on high ecological value areas and local biodiversity. Following the same trend as in Latin America, Chile has few studies on urban ecology; hence this study contributes with an assessment of avifauna and woody vegetation biodiversity in land covers belonging to the urban mosaic of Pichilemu. All field samplings were conducted during 2017 and 2018 summer times using bird counting and floristic inventories. Richness, abundance, alpha diversity indexes (Shannon-Wiener, Pielou and Simpson) of species were calculated, along with the proportion of endemic, native and threatened species. Moreover, the distance between sampling points and diverse components of the green infrastructure of Pichilemu city was analysed to demonstrate whether it influences the spatial distribution of alpha diversity parameters values. Avifauna species were classified into trophic guilds and three distinct categories (urban exploiter, urban adapter and urban avoider) basing on their response to urbanisation. Furthermore, in order to compare land covers regarding their biodiversity, Kruskal-Wallis and Dunn's test were applied. Finally, a cluster analysis was carried out to see the similarity among land covers and sampling points. The results show a bimodal distribution pattern on the Shannon index, since there are two groups of land covers with maximum values both in avifauna and woody vegetation in Pichilemu. The most diverse group in Shannon index is made up of natural land covers such as wetlands and water bodies, streams and water courses and tree-shaped scrubland. The second most diverse group in Shannon index is made up of hybrid land covers such as continuous urban fabric and discontinuous urban fabric. Most of avifauna species are native whilst the majority of woody vegetation species are exotic in Pichilemu. Even though continuous urban fabric is diverse, almost all individuals of avifauna belong to an urban exploiter species (Passer domesticus). On the other hand, individuals belonging to urban avoider species are prone to be found in diverse and less disturbed land covers such as wetlands and water bodies, streams and water courses, strands, dunes and sandbanks and tree-shaped scrubland. Likewise, these land covers contain the highest number of trophic guilds of avifauna. Regarding correlation analysis, the distance between sampling points and diverse green infrastructure components does not explain completely the spatial variability of alpha diversity parameters. Through cluster analysis, cluster comprised of wetlands and water bodies, streams and water courses, tree-shaped scrubland, shrub brush and plantations has outstanding diversity values. Therefore, these land covers should be prioritised for ecological restoration and biodiversity conservation measures.

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