Dissertations / Theses on the topic 'Potential natural vegetation'

Flora und Vegetation sind Spiegelbild naturräumlicher Potenziale ebenso wie kulturbürtiger Einflüsse. Der im Rahmen einer bodenkundlichen Tagung entstandene Artikel gibt einen textlichen und kartografischen Überblick zur potenziellen natürlichen Vegetation (pnV) Sachsens. Aktuelle Vegetationsverhältnisse finden ebenso Berücksichtigung. Die Naturregionen Tief-, Hügel- und Bergland werden aus vegetationskundlicher Sicht - unter Einbeziehung aktueller Forschungen und mit Bezug auf geologische, edaphische sowie klimatische Rahmenbedingungen - charakterisiert. Regionale Besonderheiten (z. B. die Ost-West-Gliederung des Erzgebirges) werden dabei ebenso herausgestellt wie neuere Erkenntnisse zur Verbreitung von landschaftsprägenden Waldtypen (z. B. bodensaure Eichenwälder im Tiefland).

xviii, 105 p. : ill. (some col.)
Restoration of riparian ecosystems in semi-arid riparian ecosystems requires an understanding of geomorphic, hydrologic and biologic factors and how they relate to vegetation. Such an understanding allows prioritization of restoration projects and avoidance of activities that are either unnecessary or likely to fail. In this dissertation I examined a suite of factors controlling distribution of vegetation types in the Sprague Basin, OR, and used those factors to predict potential for natural recovery. Factors ranged from basin-wide (e.g. floodplain width and slope) to local (e.g. topography, hydrology and soil texture). Results of historical analysis and photographic mapping showed that basin-wide vegetation types have remained generally stable since the early 1940s and that wide floodplains have been without woody vegetation since the late 1800s. The most prevalent changes in floodplain vegetation due to land use included reduction of shrub cover in moderately wide floodplains and associated increases in herbaceous vegetation. Soil moisture conditions were studied using piezometers and nested clusters of soil moisture tension meters. The interrelations among soil texture, elevation and distance from the channel, and vegetation (herbaceous and woody) characteristics in the riparian zone were examined along 75 transects using a generalized additive model for non linear factors and Hurdle analysis for abundance data. On the Sprague mainstem, fine soils with high recession rates supported abundant shrubs, while on the Sycan (Sprague tributary) coarse soils with readily available moisture and greater subsurface water movements supported abundant shrubs. Habitats in the Sycan were well colonized with new shrub seedlings though long term persistence was unlikely. Results show that riparian shrubs are unlikely to influence stream shade or bank stability on the mainstem Sprague whether they germinate naturally or are planted through restoration efforts, as shrubs near the channel are unlikely to persist long term. In the Sycan, germination and persistence are more likely than on the Sprague, though risks of predation, trampling from grazers, and fluvial action will be constant threats to near-channel shrubs. Results emphasize the need to understand factors controlling vegetation prior to restoration in any basin or stream segment.
Committee in charge: Patricia F. McDowell， Chairperson； W. Andrew Marcus， Member； Patrick Bartlein， Member； Scott Bridgham， Outside Member

Desertification is the diminution or destruction of the biological potential of land, and can lead ultimately to desert-like conditions. The vegetation of southern Africa is claimed to have altered over the past 100 years and much of the change is attributed to pastoral practice. In recent years however there has been much debate around the issue of the deterioration and loss of productivity of the natural rangelands, specifically those under communal management. It is one thing to claim that the vegetation has changed but quite another to produce data and analyses to show this unequivocally. Furthermore it is generally difficult to determine the nature and extent of change in natural ecosystems, as one does not know what the optimal base-line conditions should be. For this reason emphasis has been placed on developing models of potential or expected vegetation. By comparing a model of potential or expected vegetation with that of the contemporary vegetation, areas that deviate from expectation can be identified, in so doing providing evidence of the direction of change in the rangelands under various management treatments. The objective of this study was to determine shifts in the vegetation under different land-use treatments, by developing a technique to predict the potential vegetation of an area. In order to explore the nature and extent of degradation at the landscape scale a study site was selected where a range of land-use and rangeland management practices could be studied in parallel. The mid-Fish River valley consists of three markedly different units of land management, namely commercial rangelands, communal rangelands and nature conservation areas. The vegetation within the mid-Fish River valley falls within the Thicket biome and consists of three main vegetation types namely, Short Succulent Thicket, Medium Succulent Thicket and Mesic Bushclump Savanna. The creation of this potential vegetation model was dependent on the direct gradient analysis approach of relating the community patterns with environmental variables. To achieve this, floristic information was collected at sites along a topographical-moisture gradient. A Canonical Correspondence Analysis (CCA) between the environmental variables and the plant communities produced a classification from which the conditions normally associated with the major plant communities were predicted. When projected as a digital map, the qualifying sites provided a testable hypothesis of the potential vegetation. The results of this study showed a definite grazing gradient, which reflects a change from a more mesic environment towards a more arid environment with an increase in utilisation pressure. The predictive vegetation model proved to be useful for predicting the occurrence of the valley thicket communities within the Eastern Cape.

Esta dissertação trata da análise fitossociológica das formações marcescentes do Centro e Sul de Portugal, apresentando os resultados de uma análise de 186 inventários face a 481 táxones, através de uma análise hierárquica aglomerativa (Método de Ward - distância de Bray-Curtis). A par de clarificar a situação de 3 táxones e 5 nothotáxones do género Quercus pertencentes à flora Portuguesa, permitiu identificar e caracterizar 7 séries de vegetação potencial marcescentes no território em análise, cuja análise biogeográfica e bioclimática, permitiu contribuir para a actualização e definição de novos e mais precisos limites. Por fim, conclui-se que a área ocupada por vegetação potencial marcescente se encontra subestimada na área de estudo e que estes bosques primários estão extremamente degradados, encontrando-se geralmente substituídos pelas séries perenifólias vizinhas, de carácter secundário ou edafoxerófilo. Assim, as ciências Geobotânicas surgem como uma ferramenta imprescindível ao ordenamento e gestão do território, associados à conservação da biodiversidade; ABSTRACT: This work deals with the phytosociological survey of marcescent groves in Centre and Southern Portugal, and presents the results of an analysis of 186 relevés facing 481 taxa, trough Hierarchical Clustering (Ward’s method – Bray-Curtis distance). Beside the enlightening the situation of 3 taxons and 5 nothotaxons from Quercus genus belonging to the Portuguese flora, it also allowed the identification and characterization of 7 vegetation series of potential marcescent vegetation in the studied territory, which biogeographical and bioclimatic analysis, endorsed new limits definition and update. At last, we conclude that the occupied area belonging to marcescent potential vegetation is currently underestimated in the study area and these primary woodlands are deeply degraded, founding themselves generally substituted by neighbouring evergreen series with secondary or edaphoxerophilous character. As so, geobotanical sciences emerge as indispensable tool for territorial planning and managing, regarding biodiversity conservation.

Les premières utilisations des forêts par l’homme remontent au paléolithique ; depuis l’homme n’a cessé de modifier le couvert forestier. Après une introduction sur l’histoire de l’usage anthropique des forêts, trois questions de recherches sont posées : 1- Quelle est la composition des paysages forestiers ? 2- Comment se répartit le paysage végétal forestier ? 3- Comment peut-on évaluer l’impact des interventions humaines sur le paysage végétal forestier ? Le territoire d’étude est le Massif armoricain, territoire le moins boisé de France avec de grandes surfaces agricoles. Cette recherche s’inscrit dans le programme national de cartographie des végétations naturelles et semi-naturelles de France (CarHAB) initié en 2010 par le Ministère de la Transition écologique et solidaire, suivant une approche dynamico-caténale. La symphytosociologie et géosymphytosociologie s’intéressent à la fois aux aspects dynamiques (séries) et à l’intégration spatiale des communautés à différentes échelles (géoséries), et sont donc particulièrement adaptées à l’étude des écocomplexes forestiers. Une typologie des séries et des géoséries de végétation forestière du Massif armoricain est proposée. Une cartographie de la végétation actuelle (VA) et de la végétation potentielle naturelle (VPN) est réalisée sur des sites représentatifs du territoire d’étude. Enfin, une étude diachronique sur le massif d’Andaine (61) permet d’évaluer l’impact des activités humaines passées, actuelles, et de simuler l’évolution future du massif forestier. Ces informations, couplées à la carte de la VPN du site, permettent, de formuler des préconisations de gestion et de fournir aux gestionnaires un outil pour se rapprocher de la VPN, tout en conciliant une exploitation multifonctionnelle du site
The first human uses of forests date back to the Paleolithic period. Since then, man has constantly modified the forest cover. Based on the history of human forest use, three research questions emerge: 1- what is the forest landscapes composition? 2- How is the forest vegetation landscape distributed? 3- How the human impact on the forest vegetation landscape could be assessed?To answer these questions, the armorican Massif, the most least-forested territory in France with large agricultural areas, is studied. This project is part of the CarHAB national program initiated by the FrenchEcological Ministry in 2010, based on a dynamiccatenal phytosociology approach. Symphytosociology and geosymphytosociology focus on both dynamical aspects (series) and spatial distribution of communities at different scales (geoseries), and are consequently particularly well-adapted for the forest ecocomplexes study. First, a typology of the forest vegetation series and geoseries in the armorican Massif is proposed. Then, a mapping of actual vegetation (VA) and potential natural vegetation (PNV) is done on study area representative sites.Finally, a diachronic study on the Andaine massif (61) is used to assess past and present human impact and to simulate the future evolution of the forest vegetation landscape. Those informations, combined with the PNV site map, are used to develop management guidelines and provide to forest managers a tool to get closer to the PNV while ensuring a multifunctional site operation at the same time

Die vorliegende Arbeit wurde auf der Grundlage begutachteter Publikationen als kumulative Dissertation verfasst. Ziel war hier, das zeitliche Spektrum des Niederschlages unter sich bereits geänderten und zukünftig möglichen Klimabedingungen zu untersuchen, um daraus risikobehaftete Auswirkungen auf den Wasserhaushalt ableiten zu können. Ausgehend von den für Sachsen bzw. Mitteldeutschland jahreszeitlich berechneten Trends für den Niederschlag im Zeitraum 1951-2000 wurde hier der Schwerpunkt auf das Verhalten des Starkniederschlages im Einzugsgebiet der Weißeritz (Osterzgebirge) während der Vegetationsperiode gesetzt. Unter Verwendung von Extremwertverteilungen wurde das lokale Starkniederschlagsgeschehen im Referenzzeitraum 1961-2000 für Ereignisandauern von 1-24 Stunden und deren Wiederkehrzeiten von 5-100 Jahren aus statistischer Sicht beschrieben. Mittels eines wetterlagenbasierten statistischen Downscaling wurden mögliche Änderungen im Niveau des zeitlich höher aufgelösten Niederschlagspektrums gegenüber dem Referenzspektrum auf die Zeitscheiben um 2025 (2011-2040) und 2050 (2036-2065) projiziert. Hierfür wurden die zu erwartenden Klimabedingungen für das IPCC-Emissionsszenario A1B angenommen. Mittels eines problemangepassten Regionalisierungsalgorithmus´ konnte eine Transformation der Punktinformationen in eine stetige Flächeninformation erreicht werden. Dabei wurden verteilungsrelevante Orografieeffekte auf den Niederschlag maßstabsgerecht berücksichtigt. Die signifikanten Niederschlagsabnahmen im Sommer bzw. in der Vegetationsperiode sind in Sachsen mit einer Zunahme und Intensivierung von Starkniederschlägen kombiniert. Hieraus entsteht ein Konfliktpotenzial zwischen Hochwasserschutz auf der einen und (Trink-) Wasserversorgung auf der anderen Seite. Für die zu erwartenden Klimabedingungen der Zeitscheiben um 2025 und 2050 wurden für das Einzugsgebiet der Weißeritz zunehmend positive, nicht-lineare Niveauverschiebungen im zeitlich höher aufgelösten Spektrum des Starkniederschlages berechnet. Für gleich bleibende Wiederkehrzeiten ergaben sich größere Regenhöhen bzw. für konstant gehaltene Regenhöhen kleinere Wiederkehrzeiten. Aus dem erhaltenen Änderungssignal kann gefolgert werden, dass der sich fortsetzende allgemeine Erwärmungstrend mit einer Intensivierung des primär thermisch induzierten, konvektiven Starkniederschlagsgeschehens einhergeht, was in Sachsen mit einem zunehmend häufigeren Auftreten von Starkregenereignissen kürzerer Andauer sowie mit einer zusätzlichen orografischen Verstärkung von Ereignissen längerer Andauer verbunden ist. Anhand des Klimaquotienten nach Ellenberg wurden Effekte des rezenten Klimatrends auf die Verteilung der potenziellen natürlichen Vegetation in Mitteldeutschland beispielhaft untersucht. Über eine Korrektur der Berechnungsvorschrift konnte eine Berücksichtigung der trendbehafteten klimatologischen Rahmenbedingungen, insbesondere dem negativen Niederschlagstrend im Sommer, erreicht werden. Insgesamt konnte festgestellt werden, dass die regionalen Auswirkungen des globalen Klimawandels massive Änderungen in der raum-zeitlichen Struktur des Niederschlages in Sachsen zur Folge haben, was unvermeidlich eine komplexe Wirkungskette auf den regionalen Wasserhaushalt zur Folge hat und mit Risiken verbunden ist
This paper was written as a cumulative doctoral thesis based on appraised publications. Its objective was to study the temporal spectrum of precipitation under already changed or possible future climate conditions in order to derive effects on the water budget which are fraught with risks. Based on seasonal trends as established for Saxony and Central Germany for precipitation in the period of 1951-2000, the focus was on the behaviour of heavy precipitation in the catchment area of the Weißeritz (eastern Ore Mountains) during the growing season. Using distributions of extreme values, the local heavy precipitation behaviour in the reference period of 1961-2000 was described from a statistical point of view for event durations of 1-24 hours and their return periods of 5-100 years. Statistical downscaling based on weather patterns was used to project possible changes in the level of the high temporal resolution spectrum of precipitation, compared with the reference spectrum, to the time slices around 2025 (2011-2040) and 2050 (2036-2065). The IPCC A1B emission scenario was assumed for expected climate conditions for this purpose. Using a regionalisation algorithm adapted to the problem made it possible to achieve a transformation of local information into areal information. In doing so, distribution-relevant orographic effects on precipitation were taken into consideration in a manner true to scale. Significant decreases in precipitation in summer and during the growing season are combined with an increase and intensification of heavy precipitation in Saxony. This gives rise to a potential for conflict between the need for flood protection, on the one hand, and the supply of (drinking) water, on the other hand. For the expected climate conditions of the time slices around 2025 and 2050, increasingly positive, non-linear shifts in the level of the high temporal resolution spectrum of heavy precipitation were calculated for the catchment of the Weißeritz. Higher amounts of rain were found if the return periods were kept constant, and shorter return periods were found if the rain amounts were kept constant. It may be concluded from the change signal obtained that the continuing general warming trend is accompanied by an intensification of the primarily thermally induced convective behaviour of heavy precipitation. In Saxony, this is associated with an increasingly frequent occurrence of heavy precipitation events of short duration and with an additional orographic intensification of events of long duration. Using the Ellenberg climate quotient, effects of the recent climate trend on the distribution of potential natural vegetation in Central Germany were studied by way of example. Underlying climatological conditions subject to a trend, in particular the negative trend of precipitation in summer, were taken into consideration by a modification of the calculation rule. All in all, it was found that regional effects of global climate change bring about massive changes in the spatiotemporal structure of precipitation in Saxony, which inevitably leads to a complex chain of impact on the regional water budget and is fraught with risks

Die vorliegende Arbeit wurde auf der Grundlage begutachteter Publikationen als kumulative Dissertation verfasst. Ziel war hier, das zeitliche Spektrum des Niederschlages unter sich bereits geänderten und zukünftig möglichen Klimabedingungen zu untersuchen, um daraus risikobehaftete Auswirkungen auf den Wasserhaushalt ableiten zu können. Ausgehend von den für Sachsen bzw. Mitteldeutschland jahreszeitlich berechneten Trends für den Niederschlag im Zeitraum 1951-2000 wurde hier der Schwerpunkt auf das Verhalten des Starkniederschlages im Einzugsgebiet der Weißeritz (Osterzgebirge) während der Vegetationsperiode gesetzt. Unter Verwendung von Extremwertverteilungen wurde das lokale Starkniederschlagsgeschehen im Referenzzeitraum 1961-2000 für Ereignisandauern von 1-24 Stunden und deren Wiederkehrzeiten von 5-100 Jahren aus statistischer Sicht beschrieben. Mittels eines wetterlagenbasierten statistischen Downscaling wurden mögliche Änderungen im Niveau des zeitlich höher aufgelösten Niederschlagspektrums gegenüber dem Referenzspektrum auf die Zeitscheiben um 2025 (2011-2040) und 2050 (2036-2065) projiziert. Hierfür wurden die zu erwartenden Klimabedingungen für das IPCC-Emissionsszenario A1B angenommen. Mittels eines problemangepassten Regionalisierungsalgorithmus´ konnte eine Transformation der Punktinformationen in eine stetige Flächeninformation erreicht werden. Dabei wurden verteilungsrelevante Orografieeffekte auf den Niederschlag maßstabsgerecht berücksichtigt. Die signifikanten Niederschlagsabnahmen im Sommer bzw. in der Vegetationsperiode sind in Sachsen mit einer Zunahme und Intensivierung von Starkniederschlägen kombiniert. Hieraus entsteht ein Konfliktpotenzial zwischen Hochwasserschutz auf der einen und (Trink-) Wasserversorgung auf der anderen Seite. Für die zu erwartenden Klimabedingungen der Zeitscheiben um 2025 und 2050 wurden für das Einzugsgebiet der Weißeritz zunehmend positive, nicht-lineare Niveauverschiebungen im zeitlich höher aufgelösten Spektrum des Starkniederschlages berechnet. Für gleich bleibende Wiederkehrzeiten ergaben sich größere Regenhöhen bzw. für konstant gehaltene Regenhöhen kleinere Wiederkehrzeiten. Aus dem erhaltenen Änderungssignal kann gefolgert werden, dass der sich fortsetzende allgemeine Erwärmungstrend mit einer Intensivierung des primär thermisch induzierten, konvektiven Starkniederschlagsgeschehens einhergeht, was in Sachsen mit einem zunehmend häufigeren Auftreten von Starkregenereignissen kürzerer Andauer sowie mit einer zusätzlichen orografischen Verstärkung von Ereignissen längerer Andauer verbunden ist. Anhand des Klimaquotienten nach Ellenberg wurden Effekte des rezenten Klimatrends auf die Verteilung der potenziellen natürlichen Vegetation in Mitteldeutschland beispielhaft untersucht. Über eine Korrektur der Berechnungsvorschrift konnte eine Berücksichtigung der trendbehafteten klimatologischen Rahmenbedingungen, insbesondere dem negativen Niederschlagstrend im Sommer, erreicht werden. Insgesamt konnte festgestellt werden, dass die regionalen Auswirkungen des globalen Klimawandels massive Änderungen in der raum-zeitlichen Struktur des Niederschlages in Sachsen zur Folge haben, was unvermeidlich eine komplexe Wirkungskette auf den regionalen Wasserhaushalt zur Folge hat und mit Risiken verbunden ist
This paper was written as a cumulative doctoral thesis based on appraised publications. Its objective was to study the temporal spectrum of precipitation under already changed or possible future climate conditions in order to derive effects on the water budget which are fraught with risks. Based on seasonal trends as established for Saxony and Central Germany for precipitation in the period of 1951-2000, the focus was on the behaviour of heavy precipitation in the catchment area of the Weißeritz (eastern Ore Mountains) during the growing season. Using distributions of extreme values, the local heavy precipitation behaviour in the reference period of 1961-2000 was described from a statistical point of view for event durations of 1-24 hours and their return periods of 5-100 years. Statistical downscaling based on weather patterns was used to project possible changes in the level of the high temporal resolution spectrum of precipitation, compared with the reference spectrum, to the time slices around 2025 (2011-2040) and 2050 (2036-2065). The IPCC A1B emission scenario was assumed for expected climate conditions for this purpose. Using a regionalisation algorithm adapted to the problem made it possible to achieve a transformation of local information into areal information. In doing so, distribution-relevant orographic effects on precipitation were taken into consideration in a manner true to scale. Significant decreases in precipitation in summer and during the growing season are combined with an increase and intensification of heavy precipitation in Saxony. This gives rise to a potential for conflict between the need for flood protection, on the one hand, and the supply of (drinking) water, on the other hand. For the expected climate conditions of the time slices around 2025 and 2050, increasingly positive, non-linear shifts in the level of the high temporal resolution spectrum of heavy precipitation were calculated for the catchment of the Weißeritz. Higher amounts of rain were found if the return periods were kept constant, and shorter return periods were found if the rain amounts were kept constant. It may be concluded from the change signal obtained that the continuing general warming trend is accompanied by an intensification of the primarily thermally induced convective behaviour of heavy precipitation. In Saxony, this is associated with an increasingly frequent occurrence of heavy precipitation events of short duration and with an additional orographic intensification of events of long duration. Using the Ellenberg climate quotient, effects of the recent climate trend on the distribution of potential natural vegetation in Central Germany were studied by way of example. Underlying climatological conditions subject to a trend, in particular the negative trend of precipitation in summer, were taken into consideration by a modification of the calculation rule. All in all, it was found that regional effects of global climate change bring about massive changes in the spatiotemporal structure of precipitation in Saxony, which inevitably leads to a complex chain of impact on the regional water budget and is fraught with risks

This thesis presents a semi-automatic method to analyze morphometric features and landscape elements based on Self Organizing Map (SOM) as an unsupervised Artificial Neural Network algorithm in two completely different environments: 1) the Man and Biosphere Reserve “Eastern Carpathians” (Central Europe) as a complex mountainous humid area and 2) Lut Desert, Iran, a hyper arid region characterized by repetition of wind-eroded features. In 2003, the National Aeronautics and Space Administration (NASA) released the SRTM/ SIR-C band data with 3 arc seconds (approx. 90 m resolution) grid for approximately 80 % of Earth’s land surface. The X-band SRTM data were processed with a 1 arc second (approx. 30 m resolution) grid by the German space agency, DLR and the Italian space agency ASI, but due to the smaller X-SAR ground swath, large areas are not covered. The latest version 3.0 SRTM/C DEM and SRTM/X band DEM were re-projected to 90 and 30 m UTM grid and used to generate morphometric parameters of first order (slope) and second order (cross-sectional curvature, maximum curvatures and minimum curvature) by using a bivariate quadratic surface. The morphometric parameters are then used in a SOM to identify morphometric features (or landform elements) e.g. planar, channel, ridge in mountainous areas or yardangs (ridge) and corridors (valley) in hyper-arid areas. Geomorphic phenomena and features are scale-dependent and the characteristics of features vary when measured over different spatial extents or different spatial resolution. Morphometric parameters were derived for nine window sizes of the 90 m DEM ranging from 5 × 5 to 55 ×55. Analysis of the SOM output represents landform entities with ground areas from 450 m to 4950 m that is local to regional scale features. Effect of two SRTM resolutions, C and X bands is studied on morphometric feature identification. The difference change analysis revealed the quantity of resolution dependency of morphometric features. Increasing the DEM spatial resolution from 90 to 30 m (corresponding to X band) by interpolation resulted in a significant improvement of terrain derivatives and morphometric feature identification. Integration of morphometric parameters with climate data (e.g. Sum of active temperature above 10 ° C) in SOM resulted in delineation of morphologically homogenous discrete geo-ecological units. These units were reclassified to produce a Potential Natural Vegetation map. Finally, we combined morphometric parameters and remotely sensed spectral data from Landsat ETM+ to identify and characterize landscape elements. The single integrated data set of geo-ecosystems shows the spatial distribution of geomorphic, climatic and biotic/cultural properties in the Eastern Carpathians. The results demonstrate that a SOM is a very efficient tool to analyze geo-morphometric features under diverse environmental conditions and at different scales and resolution. Finer resolution and decreasing window size reveals information that is more detailed while increasing window size and coarser resolution emphasizes more regional patterns. It was also successfully applied to integrate climatic, morphometric parameters and Landsat ETM+ data for landscape analysis. Despite the stochastic nature of SOM, the results are not sensitive to randomization of initial weight vectors if many iterations are used. This procedure is reproducible with consistent results.
Avhandlingen presenterar en halvautomatisk metod för att analysera morfometriska kännetecken och landskapselement som bygger på Self Organizing Map (SOM), en oövervakad Artificiell Neural Nätverk algoritm, i två helt skilda miljöer: 1) Man and Biosphere Reserve "Eastern Carpathians" (Centraleuropa) som är ett komplext, bergigt och humid område och 2) Lut öken, Iran, en extrem torr region som kännetecknas av återkommande vinderoderade objekt. Basen för undersökningen är det C-band SRTM digital höjd modell (DEM) med 3 bågsekunder rutnät som National Aeronautics and Space Administration släppte 2003 för ungefär 80 % av jordens yta. Dessutom används i ett mindre område X-band SRTM DEM med 1 bågsekund rutnät av den tyska rymdagenturen DLR. DEM transformerades till 90 och 30 m UTM nätet och därav genererades morfometriska parametrar av första (lutning) och andra ordning (tvärsnittböjning, största och minsta böjning). De morfometriska parametrar används sedan i en SOM för att identifiera morfometriska objekt (eller landform element) t.ex. plan yta, kanal, kam i bergsområden eller yardangs (kam) och korridorer (dalgångar) i extrem torra områden. Geomorfiska fenomen och objekt är skalberoende och kännetecken varierar med geografiska områden och upplösning. Morfometriska parametrar har härletts från 90 m DEM för nio fönsterstorlekar från 5 × 5 till 55 × 55. Resultaten representerar landform enheter för områden från 450 m till 4950 m på marken dvs. lokal till regional skala. Inflytande av två SRTM upplösningar i C och X-banden har studerats för identifikation av morfometriska objekt. Förändringsanalys visade storleken av upplösningsberoende av morfometriska objekt. Ökning av DEM upplösningen från 90 till 30 m (motsvarande X-bandet) genom interpolation resulterade i en betydande förbättring av terräng parametrar och identifiering av morfometriska objekt. Integration av morfometriska parametrar med klimatdata (t.ex. summan av aktiv temperatur över 10° C) i SOM resulterade i avgränsningen av homogena geoekologiska enheter. Dessa enheter ha används för att producera en karta av potentiell naturlig vegetation. Slutligen har vi kombinerat morfometriska parametrar och multispektrala fjärranalysdata från Landsat ETM för att identifiera och karaktärisera landskapselement. Dessa integrerade ekosystem data visar den geografiska fördelningen av morfometriska, klimatologiska och biotiska/kulturella egenskaper i östra Karpaterna. Resultaten visar att SOM är ett mycket effektivt verktyg för att analysera geomorfometriska egenskaper under skilda miljöförhållanden, i olika skalor och upplösningar. Finare upplösning och minskad fönsterstorlek visar information som är mer detaljerad. Ökad fönsterstorlek och grövre upplösning betonar mer regionala mönster. Det var också mycket framgångsrikt att integrera klimatiska och morfometriska parametrar med Landsat ETM data för landskapsanalys. Trots den stokastiska natur av SOM, är resultaten inte känsliga för slumpvisa värden i de ursprungliga viktvektorerna när många iterationer används. Detta förfarande är reproducerbart med bestående resultat.
QC 20100924

Les premières utilisations des forêts par l’homme remontent au paléolithique ; depuis l’homme n’a cessé de modifier le couvert forestier. Après une introduction sur l’histoire de l’usage anthropique des forêts, trois questions de recherches sont posées : 1- Quelle est la composition des paysages forestiers ? 2- Comment se répartit le paysage végétal forestier ? 3- Comment peut-on évaluer l’impact des interventions humaines sur le paysage végétal forestier ? Le territoire d’étude est le Massif armoricain, territoire le moins boisé de France avec de grandes surfaces agricoles. Cette recherche s’inscrit dans le programme national de cartographie des végétations naturelles et semi-naturelles de France (CarHAB) initié en 2010 par le Ministère de la Transition écologique et solidaire, suivant une approche dynamico-caténale. La symphytosociologie et géosymphytosociologie s’intéressent à la fois aux aspects dynamiques (séries) et à l’intégration spatiale des communautés à différentes échelles (géoséries), et sont donc particulièrement adaptées à l’étude des écocomplexes forestiers. Une typologie des séries et des géoséries de végétation forestière du Massif armoricain est proposée. Une cartographie de la végétation actuelle (VA) et de la végétation potentielle naturelle (VPN) est réalisée sur des sites représentatifs du territoire d’étude. Enfin, une étude diachronique sur le massif d’Andaine (61) permet d’évaluer l’impact des activités humaines passées, actuelles, et de simuler l’évolution future du massif forestier. Ces informations, couplées à la carte de la VPN du site, permettent, de formuler des préconisations de gestion et de fournir aux gestionnaires un outil pour se rapprocher de la VPN, tout en conciliant une exploitation multifonctionnelle du site
The first human uses of forests date back to the Paleolithic period. Since then, man has constantly modified the forest cover. Based on the history of human forest use, three research questions emerge: 1- what is the forest landscapes composition? 2- How is the forest vegetation landscape distributed? 3- How the human impact on the forest vegetation landscape could be assessed?To answer these questions, the armorican Massif, the most least-forested territory in France with large agricultural areas, is studied. This project is part of the CarHAB national program initiated by the FrenchEcological Ministry in 2010, based on a dynamiccatenal phytosociology approach. Symphytosociology and geosymphytosociology focus on both dynamical aspects (series) and spatial distribution of communities at different scales (geoseries), and are consequently particularly well-adapted for the forest ecocomplexes study. First, a typology of the forest vegetation series and geoseries in the armorican Massif is proposed. Then, a mapping of actual vegetation (VA) and potential natural vegetation (PNV) is done on study area representative sites.Finally, a diachronic study on the Andaine massif (61) is used to assess past and present human impact and to simulate the future evolution of the forest vegetation landscape. Those informations, combined with the PNV site map, are used to develop management guidelines and provide to forest managers a tool to get closer to the PNV while ensuring a multifunctional site operation at the same time

博士
國立中興大學
森林學系所
94
Aiming at recognizing the spatial distributions of the climate and vegetation patterns in Taiwan, the climate-vegetation classification model had been implied to illustrate the complex variability through the spatialized cartography using the geographical information system (GIS), digital elevation model, Geostatistics and vegetation classification system as tools. The processes would separate into 3 parts: (1) climate submodel — interpolating the climatic grid space and designing the ecoclimatic indices; (2) vegetation submodel — confirming the vegetation types and establishing the physiognomic classification scheme of potential vegetation; (3) associating climate with vegetation and mapping the potential natural vegetation (PNV). For organizing climate submodel, started with checking the meteorological data by designing a series of examining rules. The procedure filtered out 18.7% stations with irrational coordinate and/or elevation of the metadata, and 0.83% daily mean temperature and daily precipitation data of inaccurate extreme. Then the data could be used to calculate the monthly mean temperature (Tm) and monthly precipitation (Pm) as the samples of interpolating the climatic space. The choice of the method was based on the cross validation. Modified residual Kriging was the best method for interpolating Tm space that the multiple linear regression could predict 95% variability of Tm and then overlapped the local variability from interpolating residual. Logarithmic ordinary Kriging was the best method for interpolating Pm space that performed the whole comprehensive spatial distribution of Pm and discerned the winter drought in the southwest lowland. Then Tm and Pm spaces were used as materials to assess and map the present climate-vegetation classification model. It could be demarcated 13 life zones by Holdridge model in Taiwan, but the result was not suited to local vegetation patterns. Comparatively, Kira’s warmth index (WI) was more reasonable to delimit the mountain vegetation zones, but should try to modify the ecoclimatic indices. Therefore, WI had been modified by annual range of monthly mean temperature to originate the modified warmth index (MWI) as thermal regime, and combined WI with precipitation both in the winter half-year to originate the winter drought index (WDI) as moisture regime. For organizing vegetation submodel, started with the bottom-up gateway to agglomerate plot-data. The vegetation types must be confirmed before predictive vegetation mapping, therefore designed a transforming program to combine 585 plot-data from different surveys for the purpose. But the result of the classification and ordination of the combined plot-data couldn’t display comprehensive vegetation types of Taiwan, because the plots were insufficient and disproportionate. Consequently, this study adopted the top-down gateway to divisive vegetation. After referring to Taiwan and east-Asia vegetation research papers and American national vegetation classification system etc., the physiognomic classification scheme of Taiwan had been drafted as vegetation submodel. The scheme included 4 levels: 2 classes (tundra, forest), 5subclasses (subarctic, coldtemperate, cooltemperate, warmtemperate, subtropical), 8 groups (based on phenology and types of predominant leaf) and 16 formations (based on moisture regime and predominant taxa). And, the scheme dealt completely with the diverse nomenclatures of vegetation types in the past. Finally, PNV had been mapped according to Boolean discrete methods to connect climate submodel and vegetation submodel by GIS. PNV map first represented the spatial distribution of all vegetation types of 4 physiognomic levels in Taiwan, also integrated the diverse comments of altitudinal vegetation zones and geographical climatic regions in the past. Besides, the scattered ranges of 36 dominant trees in the moisture-thermal regime and climatic zone had been drawn via coordinating 585 plot-data with MWI and WDI. This study provided a new research way and predictive framework for interpreting the complex climate and vegetation of Taiwan, and raised some remedial suggestions. The climatic grid layers, plot-data transforming program, physiognomic classification scheme of vegetation, ecoclimatic indices, moisture-thermal distribution of plants, and PNV map resulted from this study could facilitate further the managements and researches of the natural resources.

Pimelea spinescens Rye subspecies spinescens is an endemic subshrub found within temperate grasslands of the Victorian volcanic plains. It is listed as critically endangered under the Federal Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). Efforts to bolster populations using horticultural techniques have been largely unsuccessful. For long-term survival it is necessary to successfully germinate seed and employ methods which encourage wild populations to reproduce in situ. The aim of this research was to identify which factors of the biology, ecology and management of P. spinescens populations, significantly affect the species’ in situ recruitment potential.

A structure and a function of a monoculture woodland is diferent from the natural woodland condition. This is an influence of a herb layer diversity. The change of the herb layer are mainly distinguishable in the case of tree coniferous monoculture. They are the poorest at all of them viewpoint diverzity. The diversity of the woodland was analysed with an insuffiently consequence. This study get the knowledge about the species composition and the diversity of these monoculture. At the same time get the knowlege about next factores, which change diversity and species composition of stand. As a confirmation of this, coniferous monoculture are numerously and species-compositionally diferent from broadleave monoculture. And more, coniferous trees change the enviroment's condition and the whole biotopes. There are not depend any species of the herb layer at the coniferous monoculture on this studied site of Křivoklátsko.