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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

Monitoring Spatial and Temporal Changes of Agricultural Lands in the Nile Delta and their Implications on Soil Characteristics Using Remote Sensing

Hereher, Mohamed El-Desoky January 2006 (has links)
Egypt witnesses an increasing population growth concomitant with limited water and agricultural land resources. The objectives of this study were to utilize remotely sensed data for the inventory of agricultural lands in the Nile Delta, monitoring spatial and temporal variations in agricultural lands and quantifying agricultural land losses due to urbanization. Inventory of agricultural lands was designed using two approaches: thresholding and linear mixture analysis. We utilized 12 images from the Landsat satellite: 4 from Multi-Spectral Scanner (1972), 4 from Thematic Mapper (1984) and 4 from Thematic Mapper (2003) covering the entire Nile Delta. In addition, a set of 480 NDVI images were obtained from the Advanced Very High Resolution Radiometer (AVHRR) sensor that cover the period 1984-2003. Landsat images were subjected to atmospheric, radiometric and geometric corrections as well as image mosaicking. Normalized Difference Vegetation Index (NDVI) was applied and thresholding for agricultural land cover revealed that the areal extent of agricultural lands was 3.68, 4.32 and 4.95 million acres (one acre = 0.96 Egyptian Feddan) in 1972, 1984 and 2003, respectively. Linear mixture analysis of the AVHRR-NDVI with the TM-NDVI images showed that agricultural lands approached 4.11 and 5.24 million acres in 1984 and 2003, respectively. Using multitemporal Principal Component Analysis (PCA) for the TM and AVHRR images proved that reclamation activities were mostly along the western margins of the Nile Delta. Spatio-temporal analysis showed that middle delta has the highest agricultural vigor compared with the margins. Agricultural land loss was estimated in some cities within the delta as well as in Greater Cairo area. We studied the land cover classification and change in Greater Cairo area based on 5 Landsat images acquired in 1972, 1984, 1990, 1998 and 2003. Agricultural lands lost 28.43% (32,236 acres) between 1972 and 2003 with an annual loss of 1040 acres. Agricultural lands on the peripheries of Cairo and its satellite towns were the most vulnerable areas. Soil salinization was another limiting factor for land reclamation. The main conclusion confirms that remote sensing is an accurate, efficient and less expensive tool for the inventory and monitoring agricultural land change in Egypt.
2

Soil nitrogen and phosphorus depletion as a means of restoring degraded lowland fynbos ecosystems invaded by alien grasses

Ruwanza, Sheunesu 03 1900 (has links)
Thesis (MSc (Conservation Ecology and Entomology))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Much of South African lowland fynbos vegetation has been transformed by agriculture and invasive alien grass species. The artificial reduction of plant available N and P levels in soils, through the addition of carbon and calcium respectively, may provide a means of retarding the growth of alien grasses stimulated by soil nutrient enrichment. Furthermore, the competitive advantage of native lowland fynbos species adapted to nutrient impoverished soils may be increased by these additions. The above premise was tested in both field- and greenhouse-based trials by applying systemic and contact herbicides to reduce the large alien invasive grass biomass. This was followed by the addition of C as sucrose and Ca as gypsum to reduce plant available N and P respectively in the soils. The effects of these combined herbicide and soil nutrient amendment treatments on plant physiology and growth were examined in both resident alien and indigenous species and in several herbaceous and woody native species introduced as seeds and seedlings. Also, soils sampled from the different treatments in both trials were chemically analyzed. There was a total absence of seedling recruitment from seeds of all 9 indigenous species sown into soils in the field-based trial while introduced juveniles of another 9 indigenous species displayed a high mortality during the dry summer season. These detrimental effects were less severe in the greenhouse-based trial which received more regular watering and where successful seedling recruitment from seeds sown occurred in four indigenous species. Sucrose additions, both exclusively and in combination with gypsum, caused significant reductions in foliar chlorophyll, photosystem II (PSII) function and above-ground biomass of most resident and introduced alien and indigenous species. These reductions were less prominent where herbicides were applied, a possible consequence of N and P supplementation of soils by the decomposing plant biomass. This was supported by the elevated soil K, Na and N concentrations measured in soils where contact and systemic herbicides were applied. However, no significant changes in soil N or P were apparent following sucrose and gypsum additions respectively, the latter attributed to the acidic soils which precluded the formation of insoluble P complexes. A second study tested the hypothesis that exogenous sucrose addition to soils inhibits plant growth by stimulating soil microbial biomass which accumulates soil nitrogen rendering it unavailable to plants. Two native, early seral species (Dimorphotheca pluvialus (L.) Moench and Ursinia anthemoides (L) Poir. subsp anthemoides) were cultured in heat sterilized (2200C for 72 hours) and non-sterilized soils in a greenhouse under four different levels of sucrose (0, 100, 200 and 300 g m-2) supplied monthly over a four-month active growing period. Foliar chlorophyll iii contents, photosystem II (PSII) efficiencies, shoot and root lengths and dry mass, inflorescence numbers and N and P contents were measured in the plants, and N and P contents and bacterial cell and coliform numbers analyzed in the soils. Both D. pluvialis and U. anthemoides displayed significant reductions in PSII efficiency, chlorophyll content, accumulation of biomass and N and P in response increased levels of sucrose, which initially seemingly supported the hypothesis as these reductions were of substantially greater magnitude in plants cultivated in non-sterilized than sterilized soils. Despite this, there was no evidence of any significant increases in bacterial and coliform cell numbers in response to increased levels of sucrose supplied or any significant reductions in soil N and P contents following sucrose additions in both sterile and non-sterilized soils. Greater numbers of bacteria and coliforms were measured in sterilized than non-sterilized soils which corresponded with reduced soil N contents but these were not reflected in like changes in plant PSII efficiency and growth and total amounts of N taken up by plants which displayed massive increases in sterilized soils. The findings did not support the hypothesis and pointed to an abiotic mechanism of sucrose inhibition of plant photosynthesis and growth. The study concludes that the suitability of adding sucrose and gypsum to degraded renosterveld ecosystem soils to promote the competitiveness of native taxa against alien grasses is dubious. Other restoration alternatives such as natural re-colonization, transfer of soils containing viable seeds from pristine communities and top soil removal should be considered. / AFRIKAANSE OPSOMMING: Baie van Suid Afrika se laagland fynbos plantegroei is verander deur landbou en uitheemse indringer grasspesies. Die kunsmatige reduksie van plantbeskikbare N en P vlakke in die grond deur die toevoeging van koolstof en kalsium onderskeidelik, kan ’n metode wees om die groei van indringer grasse te vertraag, wat gestimuleer word deur grondvoedingstofverryking. Die kompeterende voordeel van die inheemse laagland fynbosspesies wat aangepas is tot voedingstofarme grond kan verhoog word deur die toevoegings. Bogenoemde postulaat is in beide die veld- en die glashuis-gebaseerde eksperimente getoets deur die aanwending van sistemiese en kontak onkruiddoder om die groot indringer grasbiomassa te verminder gevolg deur die byvoeging van C as sukrose en Ca as gips om die plantbeskibare N en P onderskeidelik te verminder in die grond. Die effekte van die gekombineerde onkruiddoder en grondvoedingstof verbeteringsbehandelings op die fisiologie en groei van die plante is ondersoek in beide inheemse- en residente indringerspesies asook in verskeie kruidagtige- en houtagtige inheemse spesies wat aangeplant was as sade en saailinge. Grondmonsters van die verskillende behandelings in beide studies was versamel en was chemies geanaliseer. Daar was ’n definitiewe afwesigheid van nuwe saailinge van sade van al nege indringerspesies wat gesaai was in grond in die veldgebaseerde studie, en saailinge van nog nege inheemse spesies het ’n hoë mortaliteit getoon gedurende die droë somerseisoen. Hierdie skadelike effekte was minder ernstig in die glashuisgebaseerde studie wat meer benat was, en waar nuwe saailinge suksesvol geproduseer was deur sade in vier inheemse spesies. Sukrose byvoegings, beide uitgesluit en in kombinasie met gips, het ’n afname in blaarchlorofil, fotosisteem II en bogrondse biomassa van die meeste van die residente en aangeplante indringer- en inheemse spesies getoon. Hierdie afnames was minder prominent waar onkruiddoder aangewend was, ’n moontlke oorsaak van N en P aanvulling van grond deur die verrottende plantbiomassa. Dit word ondersteun deur verghoogde grond K, Na en N konsentrasies, gemeet in grond waar kontak en sistemiese onkruiddoder toegevoeg was. Geen noemenswaardige veranderinge in grond N of P was sigbaar na byvoeging van sukrose en gips onderskeidelik nie. Laasgenoemde het bygedra tot suuragtige grond wat die formasie van onoplosbare P komplekse verkom het. ‘n Tweede studie het die hipotese getoets waar eksogene sukrose byvoeging tot grond plantegroei inhibeer deur die grond mikrobe biomassa te stimuleer wat akkumuleer wat in grond stikstof en dit nie beskikbaar maak vir plante nie.Twee inheemse vroeë intermediêre stadium spesies (Dimorphotheca pluvialus (L.) Moench en Ursinia anthemoides (L) Poir. subsp v anthemoides) was gekweek in hitte gesteriliseerde grond (2200 C vir 72 uur) en in nie-gesteriliseerde grond in ’n glashuis onder vier verskillende vlakke van van sukrose (0, 100, 200 en 300 g m-2) bygevoeg maandeliks oor ‘n 4 maande aktiewe groei periode. Blaarchlorofilinhoud, fotosisteem II (FS II) doeltreffendheid, groeipunt en wortel lengte en droë massa, blomgetalle en N en P inhoud was gemeet in die plante sowel as N en P inhoud en bakteriële sel en kolivorm getalle was geanaliseer in die grond. Beide D. pluvialis en U . anthemoides het ’n afname getoon in FS II doeltreffendheid, chlorofilinhoud, biomassa akkumulasie, N en P response op verhoogde vlakke van sukrose, wat aanvanklik aangetoon het dat dit die hipotese ondersteun want hierdie afnames wat heelwat groter in plante wat gekweek was in ongesteriliseerde grond as in gesteriliseerde grond. Daar was geen toename in baketriële en kolivorm sel getalle in rssponse tot verhoogde vlakke van sukrose byvoegings of enige noemenswaardige in grond N en P inhoud na byvoeging van sukrose in beide steriele en nie-steriele grond nie. Groot getalle bakterieë en kolivorme was gemeet in gesteriliseerde grond as in ongesteriliseerde grond. Dit korrespondeer met verminderde grond N inhoud maar dit was nie gereflekteer in veranderinge in plant FS II doeltreffendheid, groei en die totale hoeveelhede N wat opgeneem was deur plante wat ’n massiewe toename getoon het ongesteriliseerde grond nie. Hierdie bevindings het nie die hipotese ondersteun nie en het gewys na ’n abiotiese meganisme van sukrose inhibisie van plant fotosintese en groei. Die studie lei dus af dat die geskiktheid om sukrose en gips by te voeg tot gedegradeerde renosterveld ekosisteemgrond om kompetisie tussen inheemse plante en indringer grasse te promoveer, twyfelagtig is. Ander restorasie alternatiewe soos natuurlike herkolonisasie, oordrag van grond wat lewensvatbare sade bevat van onbeskadigde gemeenskappe en bogrond verwydering word oorweeg.
3

Revitalizační opatření použitelná ve vodohospodářské praxi s aplikací na konkrétních povodí. / The Arrangement of Revitalization Usable in Practice of Water Management with an Application to Particular River Basin.

VÍTEK, Josef January 2015 (has links)
The aim of this dissertation is to develop a concept of revitalization of Srbický stream, including its tributaries. The suggestion of arrangement should support an increase of water and environmental stability of the basin. It contains technical and biological revitalization, including the objects of revitalization in the bed of the stream, the estabilishment of restoration of pond reservoirs, designing the localization of wetland areas, oxbow stream restoration, afforestation of the stream banks and erosion - threatened catchment areas. The solution is based on a thorough evaluation of the documents - hydrological, pedological, hydrogeological and vegetative - and on the results of detailed field survey of the area. The proposal follows the processed local territorial system of ecological stability.
4

Šakninės pinties paplitimas Nemenčinės miškų urėdijos Meros ir Magūnų girininkijų pušynuose / Distribution of Heterobasidion annosum in Scots pine plantations of Mera and Magūnai forest districts

Navalinskas, Darius 06 June 2005 (has links)
The distribution of Heterobasidion annosum in Scots pine stands in Nemenčinė Forest Enterprise, Mera and Magūnai forest districts were examined in this Master thesis. The object of the study: Scots pine stands that were established on formerly used agricultural land, former tank range areas and the stands growing in the cut areas of mature stands. Also, the Scots pine stands where after partly clear sanitation cuttings the birch groups were planted, in purpose to avoid the disturbances of Heterobasidion annosum. The aim of the study: to summaries the information about the distribution of Heterobasidion annosum in Lithuanian forests; to study the distribution of Heterobasidion annosum in Scots pine plantations established in agricultural lands and the cut areas of mature stands. The evaluation of the effectiveness of earlier used partly clear sanitation cuttings against Heterobasidion annosum in disturbed stands was also done. Methods: the distribution of Heterobasidion annosum in the forests of Nemenčinė Forest Enterprise, Mera forest district was evaluated visually. Each studied plot was evaluated according 4 grades. 6 assessment plots in Magūnai forest district were evaluated for the effectiveness of partly clear sanitation cuttings. The stand characteristics of the remained healthy pine and birch trees were measured using standard silvicultural mensuration methods, taking the measurements of each tree at breast height, in 2 cm precision. The results: The distribution of... [to full text]
5

Lietuvos Respublikos žemės fondo administravimas / Lithuanian Land Fund administration

Rumčikienė, Gitana 03 June 2014 (has links)
Nuo 2010 m. liepos 1 d., kuomet įsigaliojo Žemės įstatymo ir Žemės reformos įstatymo pakeitimai, valstybės politiką žemės tvarkymo ir administravimo srityje įgyvendina ir dalyvauja ją formuojant pagrindinė institucija Nacionalinė žemės tarnyba. Lietuvos Respublikos žemės fondo administravimo nagrinėjimas turi tiek teorinę, tiek praktinę reikšmę. Svarbu pažymėti, kad valstybinės žemės tvarkymo ir administravimo reglamentavimas painus, sudėtingas, su egzistuojančiomis teisės aktų spragomis, todėl darbe išsamiai išnagrinėta žemės santykius reguliuojančių institucijų veikla, valstybinės žemės ūkio paskirties žemės pardavimo teisniais aspektai. Taip pat įvertinta ar apskričių panaikinimas užtikrino geresnį žemės fondo administravimą. / Since 1 July 2010 after the commencement of amendments of Land law and Land reform state policy in the area of Land resources management and administration has been implemented and led by the main authority National Land Service. The analysis of the Land fund administration of the Republic of Lithuania has both theoretical and practical significance. It is important to point out that state land management and administration regulation is rather intricate, complicated, with existing legal loopholes, therefore, the paper analyses in detail the work of institutions regulating land relations, and legal aspects of the sale of state agricultural land. The work also assesses whether the abolition of counties can ensure better Land fund administration.
6

L'évolution du foncier agricole en Algérie à travers les réformes / The evolution of agricultural land in Algeria through reforms

Baouche, Fatiha 28 January 2014 (has links)
Parler du foncier agricole en Algérie, c'est évoquer inévitablement tout un processus historique dans laquelle la terre a été l'enjeu principal aussi bien pendant la colonisation que pendant la période post indépendance, où elle a été au centre de choix politiques, voir même idéologiques. Tout un arsenal juridique mis en place pendant plus de 60 ans, pour la création et la libéralisation du marché foncier afin de faciliter les transactions foncières et réaliser la sécurisation foncière des exploitants agricoles et ce, dans le but de renforcer l'accès au foncier agricole. En Algérie, la problématique du foncier devient cruciale. Pour des raisons extrêmement variées et à des degrés divers, le foncier se trouve au centre des débats et des enjeux. Dans ce travail de recherche, nous nous intéresserons à la problématique du foncier agricole en Algérie et les différents dispositifs mis en place par l’État depuis l'indépendance pour trouver une solution à la question complexe du foncier agricole en Algérie, et ce, à travers toutes les réformes : de l'autogestion à la concession des terres du domaine privé de l’État. / Talking about the agricultural land in Algeria, is inevitably evoking a historical process in which the land was the main challenge both during the colonization and during the post independence period, where it was the centre of a political and even ideological choice. A whole legal arsenal is introduced during more than 60 years, for the creation and the liberalization of land market, in order to facilitate the land transactions and to realise a land security of farmers to reinforce the access to agricultural land. In Algeria, the land problem becomes crucial. Due to extremely varied raisons and to various degrees, the land lies at the centre of debates and issues. In this research, we focus on the land of agricultural problem in Algeria and the various devices set up by the government since the independence to find a solution to complex question of the agriculture landholding in Algeria, and that, through all the reforms of the self- management to the concession of land in the private domain of the state.

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