This thesis is part of Project of the Grant Agency of the Czech Republic No P504/11/1151, focused on the role of plants in the balance of carbon dioxide and the other greenhouse gases produced in the ecosystem of a sedge fen, which is situated on the study site Wet Meadows near Třeboň. The thesis deals with the growth dynamics of the dominant sedge, Carex acuta. The samples were taken using the method of successive harvests near the automatic meteorological station of Czech Globe, Academy of Sciences of the Czech Republic. During the growing season nine harvests were accomplished on 25.3, 15.4, 6.5, 5.6., 9.7., 5.8., 9.9., 21.10., 25.11.. On each date eight replicates were taken, i.e., a total of 72 samples within the vegetation season. The seasonal dynamic of the above ground biomass was compared between C. acuta and the other plant species on the experimental area. Both live and dead biomass, was harvested and subsequently sorted to single botanic species, dried, weighed and the values were processed using the MS Excel tables. The seasonal maximum of aboveground biomass of all plant species (both live and dead parts) was found on 9.7. (1452,72 g.m-2). Among plant species the highest values of aboveground biomass were attained by Calamagrostis canescens (1257,93 g.m-2) and C. acuta (1163,49 g.m-2). C. acuta displayed the highest density of all shoots on 15.4 (300 m-2),and the highest average weight of one shoot. The maximum length of the longest live shoot of Carex acuta was very consistent among the measurememnts.

Abstract The area of traditionally managed semi-natural meadows is declining throughout Europe. Knowledge of how to restore their species richness is urgently needed. Community manipulations by means of grazing and mowing and, on the other hand, knowledge of species-level responses as well as the responses of functional plant groups to management may help in planning appropriate restoration tools. The restoration of species richness was studied in two community-level experiments: in a sheep grazing experiment and in a mowing experiment. Three species-level studies were conducted to test the compensatory capacity of monocarpic, herbaceous plants (Gentianella amarella, Erysimum strictum, Euphrasia stricta) to simulated herbivory (10–50% of stem being cut). The perennial Linaria vulgaris was used to study whether there is any benefit of clonal integration in the tolerance of simulated herbivory. This topic was studied in a growth experiment and a 13C tracer study. In both grazing and mowing experiments, small herbs gained more space, while the dominant tall herbs subsided. The species number increased by 30% on the grazed plots, but mowing did not affect species richness, probably indicating seed limitation. At sites of this kind, seed addition could be used to promote restoration. Functional plant groups appeared to be useful in predicting the effects of grazing on plant communities. Early season grazing and mowing seem to be proper management tools in overgrown/degraded meadows. In species-level studies, all the species had relatively good compensatory capacity to repair small damage. Overcompensation was observed in response to apical damage, especially when the growing conditions were favourable, supporting the compensatory continuum hypothesis. The studied monocarpic plant species may share a common unbranched growth form where incidental apical damage leads to activation of uninitialized meristems and slight overcompensation. These responses may represent consequences of adaptation to above-ground competition, rather than adaptation to predictable herbivory. In Linaria, damaged ramets were not supported, but the neighbouring ramets seemed to compete with each other for root resources. While growing in disturbed habitats, it is more profitable for this species to invest in new ramets. The present studies showed that, while the appearance and structure of a traditional grassland rich in small-growing herbs can be restored in five years, it is more difficult to increase species diversity by mere mowing or grazing. Knowledge of the tolerance of individual species for herbivory could provide useful information for planning management practices. More studies on the effects of different management tools on different meadow types are urgently needed for the maintenance of the diversity of these valuable environments. / Tiivistelmä Perinteisellä tavalla hoidettujen luonnonniittyjen pinta-ala vähenee kaikkialla Euroopassa. Tarvitsemme enemmän tietoa siitä, miten näiden elinympäristöjen lajiston monimuotoisuus voitaisiin turvata. Tietämys laidunnuksen ja niiton vaikutuksesta kasviyhteisöihin ja toisaalta yksittäisiin kasvilajeihin tai toiminnallisiin kasviryhmiin voi auttaa tehokkaiden hoito- ja ennallistamistapojen löytämisessä. Tässä työssä tutkittiin niittyjen lajirikkauden palauttamista kahdessa yhteisötason kokeessa: lammaslaidunkokeessa ja kokeessa, jossa eri niittotapojen vaikutuksia selvitettiin. Kolmessa lajitason kokeessa testattiin monokarppisten ruohokasvien (rantaukonnauris, horkkakatkero, ketosilmäruoho) kompensaatiokykyä simuloituun herbivoriaan (10–50 % varresta poistettiin). Monivuotista kannusruohoa käytettiin tutkittaessa onko klonaalisesta integraatiosta hyötyä herbivorian siedossa. Tätä selvitettiin kasvukokeella ja hiili-13-merkkiainekokeella. Sekä laidun- että niittokokeessa matalat ruohokasvit saivat kasvutilaa korkeiden ruohojen valta-aseman vähentyessä. Laidunnus lisäsi lajimäärää 30 % koealaa kohti, mutta niitto ei vaikuttanut lajirikkauteen. Molemmissa kokeissa kasviyhteisö oli luultavasti siemenrajoitteinen. Tällaisissa kohteissa siementen lisäystä voitaisiin käyttää ennallistamiskeinona. Toiminnalliset kasviryhmät olivat käyttökelpoisia ennustettaessa laidunnuksen vaikutuksia kasviyhteisöön. Aikaisin kasvukaudella tapahtuva niitto/laidunnus näyttää sopivalta hoitokeinolta umpeenkasvaneilla niityillä. Lajitason kokeissa kaikki tutkitut kasvilajit kykenivät melko hyvin kompensoimaan vähäisiä vaurioita. Ylikompensaatiota havaittiin vasteena kärkivaurioihin erityisesti, kun kasvuolot olivat edulliset. Tämä tuki ns. kompensaatiojatkumohypoteesiä. Tutkituilla lajeilla voi olla yhtenäinen haaraton kasvumuoto, jossa ajoittaiset kärkivauriot johtavat lepotilassa olevien silmujen aktivoitumiseen ja lievään ylikompensaatioon. Nämä vasteet voivat olla seurausta sopeutumisesta valokilpailuun pikemmin kuin sopeutumisesta ennustettavissa olevaan herbivoriaan. Kannusruoholla vaurioituneita versoja ei autettu, vaan kloonin sisällä versot näyttävät kilpailevan keskenään juuriresursseista. Koska laji kasvaa häirityillä paikoilla, sille näyttää olevan edullisempaa investoida uusiin versoihin. Tämä työ osoitti, että vaikka perinteisen matalakasvuisen lajirikkaan niityn ulkonäkö ja rakenne voidaan palauttaa viidessä vuodessa, on vaikeampaa lisätä lajirikkautta pelkän niiton tai laidunnuksen avulla. Tietämys yksittäisten kasvilajien vasteista biomassan menetykseen voi auttaa sopivien hoitotapojen suunnittelussa. Lisää kokeita eri hoitotapojen vaikutuksista ja eri niittytyypeillä tarvitaan pikaisesti näiden arvokkaiden elinympäristöjen monimuotoisuuden ylläpitämiseksi.

Abstract Many plant species inhabiting the seashore meadows of the Bothnian Bay, especially early successional ones, have become threatened. Isostatic land uplift creates virgin land for early successional species to colonise. However, at the same time it gradually elevates the habitat and eventually makes the habitat unsuitable for them. Disturbances of the waterfront may slow down succession and create new empty sites. In order to persist on the shores, pioneer species have to be able to colonise new sites by seeds, vegetative propagules or growth. In this thesis I studied the status of an endangered early successional grass species, A. fulva var. pendulina, at the Liminka Bay. According to a matrix population model based on eight years of observations (1992–1999), the population seemed not to be in immediate danger of extinction. However, simulations based on four-year field observations (2000–2003) indicated that if the current trend continues, the species will decrease considerably in area in the next 30 years. In the field studies no seedlings or viable seeds of A. fulva were found. In spite of this, high genotypic diversity was found in the A. fulva population, suggesting that sexual reproduction has taken place at some time during the history of the population. Analysis of the population structure revealed a low level of genotypic differentiation between subpopulations and significant sub-structuring within subpopulations. The overall pattern of genetic variation suggests that the population has characters of both stepping-stone and metapopulation models. The results of the study on the ability of a seashore plant Potentilla anserina ssp. egedii to change its allocation of resources to sexual and vegetative reproduction according to competitive stress implied that the species can modify the allocation of resources to different life-history traits. For a plant living in disturbance-prone environment, it may be beneficial to be able to rapidly track the competition-free space formed by disturbances by changing its reproductive pattern. Management studies on three endangered seashore plant species showed that deterioration of suitable habitats of A. fulva and Primula nutans var. jokelae could be slowed down by management, and the vegetative and/or sexual reproduction of these species was enhanced. However, in the case of Puccinellia phryganodes, no positive response to management was observed.

Les écosystèmes côtiers présentent une forte production biologique, soutenue par une grande diversité de sources de matière organique particulaire (autochtones : phytoplancton, microphytobenthos, phanérogames marines, macroalgues, épiphytes ; allochtones : apports continentaux), pouvant contribuer à la production secondaire. La diversité de ces sources complexifie de manière considérable le fonctionnement écologique des systèmes côtiers — e.g. cycles biogéochimiques, réseaux trophiques — et en rend sa compréhension difficile.Une étude spatio-temporelle réalisée en 2009 dans le Bassin d’Arcachon, une lagune semi-fermée qui abrite le plus grand herbier à Zostera noltii d’Europe, a été menée afin d'estimer l’origine et la composition des matières organiques particulaire en suspension (MOPS) et sédimentaire (MOS) et d'appréhender le devenir des différentes sources de matière organique dans le réseau trophique macrobenthique. Cette approche quantitative a été effectuée principalement à l’aide des rapports isotopiques et élémentaires (δ15N, δ13C et C/N) et/ ou des acides grasA l’échelle annuelle et en moyenne pour les trois stations étudiées, la MOPS est composée principalement de phytoplancton (48 ± 2%) mais aussi de matériel continental (19 ± 4%) et de microphytobenthos (16 ± 2%), les macroalgues et les phanérogames ne contribuant que peu (8 ± 1% et 5 ± 1%, respectivement). Cette composition, qui présente une saisonnalité (faible contribution du phytoplancton en hiver au profit des apports continentaux), est principalement dépendante du climat (température) et de l’hydrodynamique / hydrodynamique sédimentaire (apports continentaux, remise en suspension du sédiment). A l’échelle annuelle et en moyenne pour les six stations ayant fait l’objet du suivi annuel, la MOS est composée principalement de sources benthiques (phanérogames : 23 ± 3% ; microphytobenthos : 19 ± 1% ; macroalgues : 19 ± 5%), mais également de matériel continental (27 ± 8%) et de phytoplancton (11 ± 2%). A l’échelle de l’écosystème (étude printanière) la composition de la MOS est similaire — avec toutefois une plus forte contribution du phytoplancton, au dépend de la matière continentale. Elle est géographiquement homogène, ce que semble favoriser l’hydrodynamique du bassin d’Arcachon associée à sa faible profondeur. La principale différence spatiale apparaît entre le sédiment subtidal (faible contribution des macrophytes au profit du matériel continental) et le sédiment de l’herbier intertidal. L’étude des voies de transfert trophique de la matière organique particulaire a mis en évidence une organisation trophique complexe avec l’existence de sous-groupes au sein des déposivores d’interface et des brouteurs. A l’échelle annuelle et à l’échelle du Bassin d’Arcachon, le microphytobenthos et les phanérogames (incluant leurs épiphytes) soutiennent 90% de la production macrozoobenthique. Cette production secondaire est principalement effectuée par les déposivores (60%). Une forte bactérivorie a été mise en évidence notamment chez les déposivores et chez le suspensivore invasif Crepidula fornicata. Les bactéries représentent ainsi un intermédiaire important dans le transfert de MOP des producteurs primaires vers les consommateurs primaires. Toutefois la pression trophique qu’exercent les consommateurs primaires de la macrofaune benthique sur les producteurs primaires est relativement modeste puisque le macrozoobenthos n’absorbe que 10% de la production primaire totale du système, ce qui rend cette dernière potentiellement disponible pour d’autres compartiments biologiques. Malgré cela l’herbier à Zostera noltii représente une ressource importante pour la macrofaune benthique. Dans le contexte de sa régression, une disparition de l’herbier engendrerait une diminution de la biomasse du macrozoobenthos. / Abstract

This thesis offers the first detailed palaeoenvironmental analysis of wetland areas within sub-Arctic enclosed homefield’s. Significance of meadows were previously mentioned only briefly in the literature, suggesting influences in settlement site selection as well as importance in quality fodder production, producing up to two thirds of total hay resources in a somewhat marginal agricultural landscape. Given the importance of hay resources in Iceland it seems unusual these areas have received so little attention to date, despite extensive research on all other aspects of the Norse farm system. The organic sediments within the meadows, given their development in-situ over extended time periods, have the ability to record aspects of the intimate relationship between societal and environmental change, and so in a robust and holistic way our methods set integrates radiocarbon measurement, tephrochronology, palynology and thin section micromorphology from the same core; reflecting these findings against existing paleoclimate and archaeological site data. This combined application of the core techniques – palynology and soil micromorphology, has proven successful in creating effective human ecodynamic records from each of the study farms. Records obtained from the three farm sites in northwest and northern Iceland exposed the varying importance and differing utilisation of these wetland areas. Meadows would appear to have played an import role in choice of settlement site across northern Iceland, through the provision of open areas, and additional and immediately available fodder resources at settlement, in a landscape dominated by dense scrub. Meadows were found to have been in continuous use, albeit at varying levels of intensity, from settlement to the present day. In this respect the semi-natural resources are found to be remarkably resilient, demonstrating little alterations to their composition following severe climatic downturns, including that of the Little Ice Age, and volcanic eruption. Acting as a robust resource and safety buffer for settlements, contributing to fodder resources where reliability of other resources is jeopardised by environmental conditions. Research in the more marginal northwest peninsula provides the first evidence of artificially created wet meadows in Iceland, developed to give sustained fodder production for over-wintering livestock in an environment that inherently had a short growing season and lacked soil fertility. A further example of the nuanced land management practices adopted in the agriculturally fragile farmscapes of the Norse North Atlantic. The findings of the thesis have wider implications for understanding the emergence of resilient and sustainable communities in agriculturally marginal environments; to this end there remains many opportunities to use palaeoenvironmental research to study ecosystem responses to natural and anthropogenic stresses, giving us a better understanding of capacities to withstand future stresses.

Under 1700- och 1800-talet genomgick jordbruket omfattande förändringar som bottnade i ett behov av att utöka odlingsmarker men framför allt effektivisera jordbruket. Utvecklingen kom att betyda ett minskat behov av ängsmarker. Enligt tidigare forskning av Skåne var utvecklingen långsammare i de skånska skogsbygderna där ängsbruket vidhölls längre än de andra bygdetyperna.   Studien syftar således till att kartlägga de faktorer som varit särskilt betydande för ängsarealens utveckling i norra Skåne under den industriella revolutionen men även under den agrara revolutionen. För möjligheten att bedriva en övergripande undersökning har ett nedslag i tid gjorts – år 1910. Socknar som endast utgörs av höglänt landskap valdes ut att ingå i undersökningen. Med hjälp av tidigare forskning togs variablerna åker, vallodling, djurhållning och skiftesreform fram. Jordbruksstatistik från varje undersökningsområde i form av sockenareal, ängsareal, åkerareal, skörd från vallodling och antal djur hämtades från BiSOS (Bidrag till Sveriges officiella jordbruksstatistik). Statistik över skiftade byar hämtades från Lantmäteriets söktjänst Historiska kartor. Diverse uträkningar gjordes utifrån statistiken för att jämföra variablernas betydelse för ängens utbredning inom varje undersökningsområde.   I resultatet framgick att åkerarealen haft direkt påverkan på ängsarealens utbredning. Vallodling och djurhållning påverkades av åkerarealens utbredning och var därmed mer indirekt påverkande. Undersökningen av skiftesreformernas påverkan på ängsarealen visade att det inte finns ett samband mellan genomförd skiftesreform och ängsareal inom det höglänta landskapet. Med det inte sagt att skiftesreformerna inte hade betydelse för minskningen av äng. Vidare bekräftade resultatet att laga skiftet varit den dominerande skiftesreformen och att flest skiften genomfördes mellan årtalen 1827–1869. / Throughout the 18th and 19th centuries agriculture encountered an extensive conversion due to urgent expansion of croplands. The conversion was essential in establishing an efficient way in land cultivation additionally leading to decrease of meadowland farming.   Recent research of Scania showed that woodlands had a continuance of meadowland farming compared to other regions of landscapes. This study intent to map out reasons contributing to the decrease of meadowland in the north of Scania during the industrial revolution but also the agricultural revolution. An impact in time was chosen to accomplish a study covering a widely spread area – the year 1910. Study sites were defined to parishes exclusively including highland lands. Based on previous research the variables cropland, grassland, livestock and enclosure of farmlands were selected. Statistics of agriculture was collected from BiSOS (Contribution to Sweden’s official agricultural statistics) in distinction to each studied parish. Statistics of enclosure was collected from the search service Historic maps by The Swedish mapping, cadastral and land registration authority. Several calculations based on the statistics were accomplished to show how the variables affected the acres of meadowland.   According to the result croplands were the main affecting variable. Grassland and livestock had a secondary affect due to their depending on the extent of cropland. Furthermore, there was no indication that enclosure directly altered the meadowland farming within the highlands of Scania and not generally for Scania. Additionally, enclosure by law was the dominating form and most were achieved during the years of 1827-1869.

This research aimed to determine whether wood microsites ("nurse logs"), which are regeneration sites in Pacific Northwest (PNW) subalpine forests, supported regeneration at timberline-alpine meadow borders. Upward advance of forests and conifer invasion into alpine meadows, which may be occurring in conjunction with climate warming, have gained worldwide attention. Successful alpine meadow seedling regeneration depends on suitable substrate availability, or microsites, for seedling establishment. To better understand factors associated with wood microsite occurrence, mechanisms of wood input were determined and four specific hypotheses were posed to assess: (1) seedling density and seedling survival; (2) growing season length, summer mean growing temperature, and growing degree hours (GDH); (3) active measures of seedling growth; and (4) global wood microsite climate associations. Of four studies, three were conducted in the Cascade Mountains of Washington state along a west - east precipitation gradient and one study, assessed various microsites globally. For Cascades-related research, wood and adjacent soil substrate temperature, moisture, and associated seedling density, survival, stomatal conductance, water potential, and leaf nitrogen were compared by percent transmitted radiation at 4 to 14 study sites. Analysis of variance (ANOVA), t-tests, regressions, and classification and regression trees (CARTs) were used to assess significance of comparisons. Wood microsites, common at 13 of 14 random Cascade sites, had greater seedling densities, greater seedling survival, greater volumetric moisture content (VWC), greater temperature, and greater number of GDH, as compared to adjacent soils. Greater seedling densities were positively associated with VWC (> 12%), conditions most commonly associated with wood substrate presence. For sites having > 25% percent transmitted radiation, positive relationships existed between stomatal conductance and VWC. Globally, high-elevation forests with wood microsites had mean annual precipitation from 86 cm to 320 cm and mean annual temperatures from 1.5°C to 4.7°C. In general, wood microsites facilitated alpine meadow regeneration better than adjacent soils. Management implications included enhanced understanding of factors associated with upward forest advance and wood use for restoration. Globally, wood microsites importance is likely underrepresented. Wood microsites role with warming climate will depend on precipitation pattern, timing, magnitude, and frequency.

Montane meadows comprise less than 5% of the landscape of the western Cascades of Oregon, but they provide habitat for diverse species of plants and pollinators. Little is known about plant-pollinator network structure at these sites. This study quantified plant-pollinator interactions over the summer of 2011, based on six observations of 10 permanent subplots in 15 meadows, stratified by size and isolation. The study examined (1) relationships between richness and abundance of flowers, pollinators, and interactions; (2) distribution of abundance and richness of flowers, pollinators, and interactions with regards to surrounding meadow habitat; (3) change in flower and pollinator abundance over the season; (4) factors associated with the presence of various guilds of pollinators; and (5) the structure of plant-pollinator networks. The study showed that (1) richness of pollinators increased 2x faster than richness of flowers with increased abundance; (2) density of flowers and interactions was positively correlated with meadow size and diversity of pollinators and interactions were both correlated with surrounding habitat at two spatial scales; (3) peak flower abundance coincided with or preceded peaks in pollinator populations; (4) abundance of three guilds of bees exhibited different patterns of association to surrounding habitat and meadow soil moisture corresponding to various dispersal potential and phenology of guild species; and (5) the number of network pairings for plants and pollinators increased with increasing species richness of potential interaction partners and all networks were found to be significantly nested. Results of this study indicate that plant-pollinator networks are complex assemblages of species, in which spatial and temporal patterns of habitat affect species composition and network structure. In particular, flower and pollinator abundance and richness are depressed in small and isolated meadows. Significant nestedness emerged as a pattern of network level organization across the study meadows. / Graduation date: 2013

Les écosystèmes prairiaux alpestres sont supposés être très sensibles au changement climatique. Cependant leur long historique fait de variation du climat et de multiples siècles d'utilisation des terres peut avoir sélectionné des mécanismes de résilience écologique à la variabilité climatique et aux stress climatiques extrêmes. Nous avons utilisé un dispositif expérimental de grande envergure pour explorer les mécanismes de réponses des prairies subalpines à une combinaison d’extrêmes météorologiques hivernaux (fonte des neiges précoce) et estivaux (sécheresse) en fonction de la composition fonctionnelle des communautés végétales et des pratiques de gestion des terres. La composition fonctionnelle des prairies a été manipulée à l’aide d’assemblages de trois espèces de poacées en différentes abondances relatives, représentant in fine un gradient d’utilisation des ressources allant de la conservation à l'exploitation. De manière générale, la composition fonctionnelle a été le principal déterminant de tous les paramètres observés pour la performance individuelle des plantes, les réponses intraspécifiques des plantes, la décomposition de la litière et les processus de recyclage de l'azote. Le fonctionnement des écosystèmes prairiaux dominés par des plantes conservatrices a été remarquablement résistant aux traitements climatiques extrêmes, tandis que les écosystèmes prairiaux dominés par des plantes plus exploitatrices ont été plus résilients. Les pratiques de gestion ont modulé ces réponses et plus particulièrement dans le cas des communautés exploitatrices. Les allocations souterraines aux réserves glucidiques et aux pools d'azote microbiens ont été identifiées comme deux mécanismes clés sous-tendant les réponses des communautés résilientes. Néanmoins, des répercussions à plus long terme du changement climatique pourraient être observées, causées par un épuisement successif des réserves végétales et une diminution des retours azotés vers le sol via les processus de décomposition. / Alpine grassland ecosystems are presumed to be highly sensitive to climate change, yet their long history of climate variability, and multiple centuries of land use may have selected for mechanisms of ecological resilience to climate variability and climate extremes. We used a large experimental design to explore patterns and mechanisms for responses of subalpine grasslands to combined winter (snow removal) and summer (drought) weather extremes depending on plant functional composition and management. Plant functional composition was manipulated by establishing grass mixtures with three species representing a conservation to exploitation gradient planted at varying relative abundances. Overall, functional composition was the primary determinant of all observed parameters for plant individual performance, intraspecific plant trait responses, litter decomposition and nitrogen recycling processes. The functioning of grassland ecosystems dominated by conservative plants was remarkably resistant to extreme weather treatments, while grassland ecosystems dominated by more exploitative plants were more resilient. Management altered these responses mostly in the case of exploitative communities. Belowground allocation to carbohydrate reserves and to microbial nitrogen pools were identified as two key mechanisms underpinning these resilient responses. Longer-term impacts of climate change may however unfold through the exhaustion of plant reserves and decreasing nitrogen returns to soils via decomposition process.

Three seasons of initial succession were followed in the frame of this thesis after a restoration project in a section of the Stropnice River and its floodplain. The succession tends towards formation of community of alluvial meadows, which is prevailing biotope in the neighborhood of the restored part. Strong factor influencing the course of succession is wetness of the substrate, which is partially given by distance of a site from the water-course and by the difference in the altitude of a site and of the river water table. Synantrophic species were most abundant in the first year (2014), followed by meadow and wetland species (2015, 2016).