Abstract Plants and soil organisms are closely linked. Plants are the sole source of carbon in the soil and soil organisms are responsible for recycling of nutrients, making them available for plant growth. To understand the function of a system, it is important to understand the interactions between the soil and plants. These interactions have mainly been studied in temperate areas, with few studies in the arctic and subarctic. The aim of this thesis was to investigate the effect of ecological disturbances in sub- and low-arctic grasslands on soil organisms and plant-soil feedback relationships. The effect of removal of vegetation, replanting of a local plant species, and different components of grazing (trampling, defoliation and return of nutrients) on soil decomposer organisms were studied. Whether short term effects of defoliation depended on plant species community was also studied, as well as whether defoliation in the field could create changes in the soil system systems that affect the growth of seedlings. Experiments were conducted under both controlled greenhouse conditions and in field sites. The results showed that physical disturbance (removal of vegetation and trampling) reduced the abundance and diversity of soil biota. Defoliation increased soil decomposer abundance in the short term. Plant species composition did not affect soil biota and only in a few cases did it changes their responses to defoliation. In the long-term, effects of fertilization and defoliation on the soil biota were context-dependent. However, defoliation did create changes in the soil that reduced the growth of seedlings planted into the soil. Furthermore, plant species community and spatial heterogeneity (revealed by blocking) had important effects on the soil communities.

Thesis (M. Sc. (Botany)) -- University of Limpopo, 2019 / The Woodbush Granite Grassland (WGG) is the most threatened vegetation type in Limpopo Province of South Africa. However, it has a high conservation value, because few examples of this vegetation type remain in southern Africa. Unfortunately, a large part of it is not formally conserved, making this the vegetation type most urgently in need of conservation. The study aimed at mapping transformation of the WGG, identifying species of conservation importance, and providing a management plan required for maintenance of the WGG. The objectives of the study included compiling a transformation map for the WGG, which also involved describing the remaining patches of the WGG that are in a natural or near-natural state. It also provides information on species of conservation importance, medicinal plants and threats to the WGG. On the four main study sites (Iron Crown Grassland, Haenertsburg Grassland, Ebenezer Dam Nature Reserve Grassland, and Ebenezer Dam Perimeter Grassland), quadratic plots were randomly set with a size of 25 x 25 m, and subplots of 1 x 1 m. Vegetation mapping was done during summer and winter. At each plot data was collected on all plant species occurring within the quadrat. A cover score was assigned to each plant species. A modified Braun-Blanquet data collection sheet was employed to obtain baseline data. For transformation mapping GeoTerra Image (GTI), land cover data were extracted for the WGG, using the modelled boundary as a mask, with 5 categories of transformation defined. Of the surveyed sites, the Ebenezer Dam Nature Reserve Grassland has the highest number of species, while the Haenertsburg Grassland contained the most endemic species of conservation importance. Rare species such as the Aloe zebrina, which does not occur in any formally protected area, and medicinal plants such as Athrixia phylicoides, occur on the WGG. All sites have importance with regard to WGG conservation. Identified threats include the spread of alien invasive plants, uncontrolled collection of medicinal plants, urban development, and poorly timed anthropogenic fire. vi The WGG underwent transformation to other land classes. Grassland clearing for plantations and cultivation were the main causal factors behind the observed WGG losses, with a total of 55.25% transformed. Transformation by afforestation is considered irreversible. It is concluded that the WGG is of conservation importance, and that some of it has been transformed to exotic timber plantations. The grassland is under various threats; therefore it is recommended that: (1) The proposed management plan provided in this study be adopted, (2) further research on the WGG be done on medicinal plants, (3) phytosociological and floristic studies be conducted and, (4) the effects of fire and alien invasive plant species on the grassland be investigated.

No description available.

Many land systems experience massive ecological pressure due to ongoing land use changes for the increasing demand for food, but also need to sustain essential ecosystem services. Computer-based model scenarios help to anticipate the consequences of different socio-economic future transition pathways for humans and nature and evaluate trade-offs between various demands on land. In many grassland ecosystems, the processes of agricultural abandonment in less attractive regions coexist with agricultural intensification in others. At the same time, the ecological value of natural grassland is rarely considered in decision making. By using the CLUMondo land use modelling framework I mapped the future composition of the land system of Orenburg province under five socio-economic scenarios with different ranges of food production intensification. The outcomes allowed me to identify hotspot areas for arable land expansion, grassland restoration, and agricultural abandonment. Most agricultural expansion is prevalent in three scenarios with high ambition for food production, and, without active policy interventions, some natural grassland areas in northern parts of the province are likely to be converted to cropland. In a scenario with low demand for food production, large areas in southern parts could be abandoned creating good opportunities for grassland restoration on former cropland, but possibly having negative socio-economic consequences, such as people’s migration to northern parts of the province. In a scenario with lesser ambition for crop production, but an increase in meat production, agricultural abandonment is less widespread and will even include some additional conversion of cropland to pasture. With appropriate policies aimed at supporting sustainable grazing practices (together with favourable global socio-economic conditions), such scenario can provide an opportunity for satisfying demands for food, providing livelihoods, and ensuring the flow of ecosystem services by grassland ecosystems.

Les prairies permanentes sont reconnues pour les nombreux services agronomiques et environnementaux qu’elles fournissent. Cependant, elles sont aujourd’hui encore retournées ou menacées de l’être au profit de productions plus rentables, ou abandonnées dans le cas des prairies humides où les conditions d’exploitation sont soumises à de nombreuses contraintes. Concilier objectifs de production et environnementaux afin de maintenir une activité agricole extensive au sein des prairies temporaires s’avère alors indispensable. Dans ce contexte, des études multi-services ont été réalisées au sein des prairies humides du Parc Naturel Régional (PNR) des marais du Cotentin et du Bessin (Normandie) ainsi que dans des prairies mésophilesaux conditions pédoclimatiques contrastées situées en Normandie, en Lorraine et en Auvergne. L’étude s’est focalisée sur 3 catégories de services écosystémiques (SE) telles que définis par le Millenium Ecosystem Assessment: la diversité floristique et fonctionnelle comme services de support, la qualité et la production du fourrage comme services d’approvisionnement et les stocks de carbone organique et les teneurs en carbone soluble du sol comme services de régulation. Afin de mettre en évidence la part du fonctionnement des communautés végétales dans le déterminisme des SE, la mesure de traits fonctionnels foliaires a été réalisée à l’échelle de l’espèce et/ou de la communauté végétale. Une partie de ces travaux se focalise sur les relations entre le fonctionnement des communautés végétales et la qualité du fourrage ainsi que l’impact des conditions hydriques du solsur les teneurs en micronutriments des espèces dans les prairies humides.Les résultats ont mis en évidence, qu’en fonction du groupe fonctionnel considéré, le SLA ou le LDMC étaient de bons proxies de la digestibilité des fourrages des prairieshumides. Les dicotylédones ont des teneurs en micronutriments plus élevées que les monocotylédones. Nos résultats montrent que l’inondation influence plus la composition élémentaire des espèces intolérantes aux inondations que les espèces adaptées et qu’elle n’a pas incidence sur la production de biomasse. De manière générale, le fonctionnement des communautés végétales n’explique pas à lui seul les relations entre les SE. La qualité du fourrage est liée au fonctionnement des communautés végétales ainsi qu’à la diversité floristique et fonctionnelle mais seulement en prairies humides. En prairies mésophiles, l’historique de la gestion ou la structure du paysage pourrait être déterminants. Par ailleurs, nos résultats montrent que les stocks de C organique dans le sol des prairies mésophiles et humides sont étroitement liés à sa nature.Les indicateurs des SE combinent les prairies humides en 4 groupes distincts en selon la nature du sol et la gestion (fauche ou pâturage). Globalement, les bouquets de services rendus par les prairies humides sont mieux équilibrés que ceux rendus par les prairies mésophiles, ces derniers ne se distinguant pas les uns des autres selon la localisation géographique des prairies mésophiles. Les prairies gérées de manière extensive fournissent de meilleurs services environnementaux que des prairies gérées de manière intensive et une qualité fourragère équivalente. / Permanent grasslands are recognized for the many agronomic and environmental services they provide. However, they are still plowed or threatened to be in favor of more productive cultures, or abandoned in the case of wet grasslands, where the conditions of exploitation are subjected to many constraints. Reconciling production and environmental objectives in order to maintain extensive agricultural activities is therefore essential in permanent grasslands. In this context, multi-service studies have been carried out in the wet grasslands of the Regional Natural Park (PNR) of the Cotentin and Bessin marshes (Normandy, France) as well as in a set of mesophilous grasslandsofcontrasting pedoclimatic conditions located in Normandy, Lorraine and Auvergne. The study focused on 3 categories of Ecosystem Services (ES) as defined by the Millennium Ecosystem Assessment: floristic and functional diversity as support services, quality and forage production as supply services and stocks of organic carbon and soluble carbon soil contents as regulatory services. In order to analyzethe role of plant community functioning in the ES determinism, the measurement of leaf functional traits was carried out at the species and/or the plant community scales. Part of this work focuses particularly on the relationships between plant communities functioning and forage quality, and soil moisture conditions impact on micronutrient contents of species in wet grasslands. The results showed that, depending on the functional group, SLA or LDMC were good proxies for the digestibility of wet grassland forages. Dicots have higher micronutrient contents than Monocots. Our results show that flooding influences the elemental composition of flood-intolerant species more than adapted species and does not affect biomass production. In general, the plant community functioning does not explain all the relationship between ESs. Forage quality is linked to the plant community functioning as well as thefloristic and functional diversity but only forwet grasslands. In mesophilic grasslands, the history of management or the landscape structure could be important drivers. In addition, our results show that organic C stocks in the soil of wet and mesophilic grasslands are closely related to soil nature. ESs indicators have brought together 4 distinct groups of wet grasslands according to soil nature and management practices (mowing or grazing). Overall, the ESs packages offered by wet grasslands are better balanced than those provided by mesophilic grasslands, the latter being indistinguishable from another according to the geographical location. Extensively managed grasslands provide better environmental services than intensively managed grasslands and equivalent forage quality.

Wild ungulates are considered one of the major drivers for shaping terrestrial ecosystems, which has been developing since the early Cenozoic. Understanding the effects of ungfulates on vegetation is necessary for qualified knowledge how European landscape looked prior to human habitation and how it would look like without human intervention. Further, such understanding is of practical importance as management information necessary for managing abandoned landscapes. While the present-day wild ungulate European fauna does not contain several large grazers like auroch (Bos primigenius) anymore, the landscape has long been affected by them. It thus possesses historical experience of response to large grazers, which has been further maintained by livestock grazing. Importantly, the European landscape is experiencing a steady increase of populations of deer (Cervidae) and wild boar (Sus scrofa) with major effects of vegetation and landscape structure. While the effects of these present-day dominants have been studied mainly in forest habitats, there is a growing evidence that they both promote species diversity of forest understory and, interestingly, preferably feed in open vegetation and thus can affect broader landscape heterogeneity. The main aim of this thesis is therefore to examine effects of...

Habitat fragmentation can adversely affect species populations due to reduced genetic diversity and increased population differentiation due to habitat isolation, reduced population size, and disruption of gene flow. Many species suffer from habitat fragmentation and isolation, and Campanula glomerata is a good example of a species that is noticeably declining in many places due to changes in landscape management. The question is how the model species responds to these changes and whether is the change are reflected in genetic diversity and population structure. The aim of this work is to determine the degree of genetic diversity and to reveal the genetic structure of populations of the model species C. glomerata on a small regional scale in the White Carpathians. This system will allow us to compare populations from two different regions that have been affected to varying degrees by agricultural intensification and fragmentation in the last century. It is a southwestern and northeastern part of the region, which differs from each other in the history of management in the landscape, but also in the continuity of meadows, species composition and environmental conditions. For this purpose, I developed and optimized a total of 16 usable microsatellite markers, 4 of which come from related species of...

Die Steppen Kasachstans haben seit dem Zusammenbruch der Sowjetunion einen tiefgreifenden Wandel erfahren. Insbesondere die Veränderung der Landnutzung, welche traditionell von der Acker- und Weidenutzung geprägt ist, sowie die daraus resultierenden Effekte auf das Feuerregime sind aktuell noch nicht ausreichend verstanden. Das Hauptziel dieser Dissertation besteht daher in der Kartierung und Analyse der Veränderungen im Mensch-Umweltsystem des nördlichen Kasachstans seit den 1980er Jahren. Ein auf jährlichen Landsat-Zeitreihen basierender Ansatz wurde entwickelt, um den Zeitpunkt der Aufgabe und Rekultivierung von landwirtschaftlichen Flächen mit hoher räumlicher und zeitlicher Auflösung zu dokumentieren. Dieser Datensatz ermöglichte z.B. die Schätzung des Anteils organischer Kohlenstoffbindungen im Boden auf Basis der Nutzungsgeschichte der letzten Jahrzehnte. Eine Kartierung der Änderungen im Feuerregime zeigte eine siebenfache Zunahme an verbrannter Fläche und eine Verachtfachung von Bränden innerhalb des Untersuchungszeitraumes. Sowohl landwirtschaftliche Feuer als auch die Landaufgabe waren mit einem erhöhten Brandrisiko assoziiert. Darüber hinaus wurde mithilfe von Spektralindizes und einem Random Forest Modell quantifiziert, wie sich der Beweidungsdruck nach dem Zerfall der Sowjetunion verändert hat. Die Analyse ergab einen Rückgang des Beweidungsdrucks in der kasachischen Steppe nach 1992, meist in der Nähe von aufgegebenen Nutzviehhaltestationen. In dieser Dissertation konnte gezeigt werden, wie Landsat-Zeitreihen genutzt werden können, um den Einfluss von Landnutzungsänderungen auf die Ökologie von Steppen besser zu verstehen. Die entwickelten Datensätze ermöglichen es, die Prozesse, die zur Landaufgabe und den damit zusammenhängenden Auswirkungen auf die kasachische Steppe führten, zu entwirren und können zur Entscheidungsfindung in der Landnutzungs- und Naturschutzplanung verwendet werden. / The steppes of Kazakhstan are one of the world regions that experienced massive changes in land-use intensity and widespread land-use change after the breakdown of the Soviet Union. Cropping and grazing regime changes across the steppes of Kazakhstan are understudied, and related spatio-temporal changes, e.g. in fire regimes, are still poorly understood. The main research goal of this thesis was to develop a methodology to map related change at appropriate scales and to provide novel datasets to enhance our understanding of how the coupled human-environment in Northern Kazakhstan has changed since the 1980s. An approach was developed to identify the timing of post-Soviet cropland abandonment and recultivation in northern Kazakhstan. Knowing the timing of abandonment allowed for deeper insights into what drives these dynamics: for example, recultivation after 2007 happened mainly on land that had been abandoned latest. Knowing the timing of abandonment allowed for substantially more precise estimates of soil organic carbon sequestration. Mapping changes in fire regimes highlighted a sevenfold increase in burnt area and an eightfold increase in number of fires after the breakdown of the Soviet Union. Agricultural burning and abandonment were associated with increased fire risk. Grazing probabilities, derived from Landsat using a random forest, were found to provide the best metrics to capture grazing pressure. The analysis revealed a general decline in grazing pressure in the Kazakh steppe after 1992, especially near abandoned livestock stations. Collectively, the dissertation highlights how dense records of Landsat images can be utilized to better understand land use changes and the ecology of steppes across large areas. The datasets developed within this thesis allow to disentangle the processes leading to and the impacts of agricultural abandonment in the temperate Kazakh steppes, and may be used to support decision-making in land-use and conservation planning.

The study was focused on disturbances by wild boar (Sus scrofa) and their impact on vegetation of semi-dry grasslands (Festuco-Brometea) dominated by Brachypodium pinnatum. The research was conducted in military area Hradiště in hilly region of the Doupovské hory. Wild boar rooting activities is main source of disturbances regime in this abandoned, previously agricultural area. The vegetation of artificial small scale soil disturbances was compared to undisturbed control plots and vegetation of natural disturbances by wild boar. Experimental plots were established during the summer 2007. Consequently a vegetation survey of these plots was carried out and soil was mechanically disturbed. Succession on disturbances was annually monitored. The surrounding natural disturbances were also mapped three times a year as a potential source of diaspores and to assess their frequency and effect on the landscape level. The list of species in the 2m, 4m and 16m distance from the experimental plot was also made. Results: Disturbances by wild boar increased species diversity and spatial heterogeneity of semi-dry grasslands. There were some species found on experimental plot, which were present not in the surrounding matrix. Most of them belong to hemicryptophytes and species with long-term persistent diaspores. Presence of...

Les prairies supra-forestières sont des écosystèmes bien représentés dans les milieux de montagne et qui s’avèrent vulnérables aux changements climatiques et aux modalités d’utilisation des terres. Dans ce contexte, l’objectif principal de cette thèse a été d’évaluer l’effet des forçages climatiques et du pastoralisme sur la végétation des prairies supra-forestières à différentes échelles spatio-temporelles. En particulier, nous avons cherché à comprendre les réponses des prairies à la variabilité interannuelle du climat (température et précipitation), aux tendances sur le long terme (réchauffement) et aux évènements extrêmes (vagues de chaleur et sécheresses) ; ainsi qu’aux modalités de la gestion pastorale (charges et calendriers de pâturage). Pour cela, nous avons réalisé des analyses sur un nombre de métriques phénologiques, météorologiques et pastorales. Les premières, dérivées principalement de l’indice de différence normalisée de la végétation (NDVI) à partir d’images satellite de moyenne (MODIS) et de haute résolution (Landsat et SPOT), ainsi que des données acquises au sol à la volée et en continu sur cinq alpages. Les deuxièmes, calculées à partir des ré-analyses du modèle climatique SAFRAN de Météo-France. Les troisièmes, estimées à partir des données des Enquêtes Pastorales régionales (1996-1997 et 2012-2014), et des cahiers d’alpage du dispositif Alpages Sentinelles. Concernant la végétation des prairies supra-forestières, nos résultats mettent en évidence : (i) des tendances au verdissement assez généralisées, (ii) des tolérances plus importantes aux vagues de chaleur qu’aux périodes de sécheresse estivales, (iii) des sensibilités plus importantes aux facteurs climatiques qu’aux pressions de pâturage, (iv) des réponses légères mais positives aux modalités de gestion pastoral, et (v) un potentiel de repousse en fin de saison. L’originalité de nos résultats a été de montrer l’existence de relations plus fortes entre les facteurs climatiques et la végétation des prairies, qu’entre cette dernière et le pâturage. Ils ont également éclairé les apports de l’utilisation de la télédétection dans l’étude de ces milieux. / Mountain grasslands are wide distributed ecosystems which are particularly vulnerable to climate and land use changes. In this context, the main objective of this thesis was to assess the effect of climate and pastoral drivers on mountain grasslands vegetation at different spatiotemporal scales. In particular, we wanted to understand plant responses to annual variations of climate (temperature and precipitation), long term warming and extreme events (heat waves and droughts); as well as the land management impact (grazing intensity and calendars). Hence, we performed several analyses using phenological, meteorological and pastoral metrics. First, we derived phenological metrics mainly from the Normalized Difference Vegetation Index (NDVI) extracted from two sources: satellite remote sensing images at moderate (MODIS) and high (Landsat and SPOT) resolution and field remote sensing measures acquired with portable and fixed sensors over five mountain grasslands. Second, we estimated meteorological metrics from reanalysis of the climatic model SAFRAN provided by Météo France. Third, we estimated pastoral metrics from two regional pastoral surveys (1996-1997 and 2012-2014) and several local documents (“cahiers d’alpage”) produced within the project “Alpages Sentinelles”. Regarding mountain grasslands vegetation, our results showed: (i) widely distributed greening trends, (ii) higher tolerance to heat waves than to droughts, (iii) higher sensibility to climate factors than to grazing pressures, (iv) weak but positive responses to grazing, and (v) a regrowth potential at the end of the season. The originality of our results was to exhibit the stronger relationships between climate factors and vegetation phenology, than between the latter and grazing pressures. Moreover, we highlighted the important contributions of remote sensing data to study mountain ecosystems.