Dissertations / Theses on the topic 'Alpine grassland'

The extensive applications of high-throughput sequencing have remarkably improved our abilities to analyze soil microbial community profiles. However, due to the paucity of knowledge on characterizing most of the microbial lineages, the predominant challenge in investigating soil microbes has shifted from community composition descriptions to the interpretations for their ecological implications. Currently, assessing the relative abundances of microbial lineages with different life strategies (i.e., copiotrophs and oligotrophs, analogous to r- and K- specialists, respectively) is the most widely used approach to explore the ecological implications of microbial community profiles. Moreover, the relative abundance of copiotrophs and oligotrophs is usually closely correlated with soil microbial respiration rates. Collectively, identifying the life- strategies of soil microbial lineages is not only essential to interpreting the ecological implications of microbial community profiles, but also crucial to understanding the links between microbial communities and their ecological functions. Nonetheless, with almost all of the life-strategy classification efforts being made at the phylum level, the life strategies of microbial lineages at finer taxonomy levels remain largely unknown. Although the majority (> 90%) of soil microbes are dormant and contribute little to the ecosystem functioning, the life-strategy classifications are seldom conducted targeting the active microbial populations. Furthermore, grasslands cover around one-third of the global terrestrial surface, providing essential services for maintaining our planetary health. However, the life-strategies of grassland soil microbial lineages were far less identified than those of forests and farmlands. Therefore, my thesis aimed to determine the life strategies of total and active prokaryotic lineages in grassland soils, and then tried to apply them to interpret the responses of alpine meadow soil prokaryotes to environmental changes. Briefly, in Chapter 2, I assessed the possibilities of using the methods based on 16S rRNA to identify the prokaryotic life strategies. Subsequently, in Chapter 3, I classified grassland soil prokaryotic lineages (from kingdom to genus) into copiotroph-oligotroph categories, using methods based on 16S rDNA and rRNA. Finally, in Chapters 3 and 4, I tried to interpret the responses of prokaryotic communities to litter amendments, phosphorus fertilization, livestock grazing, and experimental warming based on the proportional changes of copiotrophic and oligotrophic microbial lineages. In Chapter 2, soil samples collected from a Tibetan alpine meadow were amended with different amounts of glutamate. The 16S rDNA and rRNA copies, as well as community structures based on 16S rDNA and rRNA were analyzed using real-time PCR and terminal-restriction fragment length polymorphism, respectively. Except for 16S rRNA copies and rRNA-rDNA ratios, all of the indices based on rDNA and rRNA were significantly correlated with the soil microbial respiration rates. However, the 16S rRNA-based bacterial community structure could explain 72.7% of the soil microbial respiration variations, which far outperformed the other indices. These findings indicate that the 16S rRNA-based community structure is a sensitive indicator for soil microbial respiration activity, and also highlight its potential for identifying microbial life strategies (i.e., copiotrophs and oligotrophs). This study provides the basis for the 16S rRNA-based life strategy classifications of prokaryotic lineages in Chapter 3. In Chapter 3...<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>School of Environment and Sc<br>Science, Environment, Engineering and Technology<br>Full Text

The terrestrial biosphere represents a large pool of carbon, whose cycle is governed by the opposed processes of CO2 uptake (photosynthesis) and release (respiration) from and to the atmosphere. Considering the role of carbon dioxide in the observed global warming, monitoring, understanding and modeling carbon exchange of ecosystems is a critical issue in climate change researches. Moreover because of the multiple implications of vegetation structure dynamics on ecosystem carbon fluxes, monitoring and modeling plant phenology is also of increasing scientific interest. Among terrestrial ecosystem grasslands cover almost 40% of ice-free land surface, nevertheless their role as sources/sinks of atmospheric CO2 is not well clarified. In this study the eddy covariance method was used to assess CO2 exchange at an high elevation unmanaged grassland in the North-Western Italian Alps (Aosta Valley - Torgnon), during three years (2008-2010) of measurements and to evaluate how environmental factors affect photosynthetic processes. The seasonal and inter-annual course of net ecosystem CO2 exchange (NEE), ecosystem respiration (Reco), gross primary production (GPP) and the main meteorological variables was analysed. The three growing seasons had a similar seasonal dynamic, characterised by a fast rise of photosynthetic activity after snow-melt followed by a gradual autumnal decline. Regarding the meteorological variables, only precipitation, soil water content and snow depth differed markedly among two of the studied years (2009-2010) compared to other factors which showed only small differences in restricted time-periods. To better interpret how weather variables modulate ecosystem processes at multiple time-scales (day, week, month, year), a quantitative analysis was performed applying wavelet coherence between time-series of GPP and time-series of different meteorological factors (air and soil temperature, soil water content and photosynthetically active radiation). Eddy covariance and meteorological data were combined with proximal sensing measurements to identify links between optical indices, canopy development and fluxes. In particular a colour index derived from continuous digital imagery (i.e. Greenness Index, (GI), based on RGB channels) and indices derived from an HyperSpectral System (Hyperspectral Irradiometer, HSI) were used as input to simulate GPP, based on a light use efficiency (LUE) model. Results showed that a LUE model driven by optical indices and meteorological variables is able to describe the GPP trend in the two years of study. In particular the use of different model formulations provided insights on the role of the main meteorological factors controlling grassland photosynthesis. The comprehension of these relationships at stand level is essential for extrapolating such information at different spatial scales.

Stoats are introduced mammalian carnivores implicated in the decline of several of New Zealand�s endemic species. Most research into stoats in New Zealand has focused on beech forest habitat, especially in years of peak stoat abundance following heavy beech seedfall and peak cohorts of mice. In New Zealand, alpine grasslands occur above the altitudinal limit of beech forest (900-1000 m a.s.l.). Although previous research has shown stoats to be present there, little is known about the ecology of stoats in alpine grasslands. This research aimed to test whether alpine grasslands were a marginal habitat occupied by surplus stoats that had spilled over from beech forest populations, i.e. a sink habitat. The alternative is that alpine grasslands are a desirable habitat deliberately exploited by stoats. This question was answered using mark-recapture, radio-tracking, diet analysis and a food addition experiment. Another objective was to determine whether nest survival is higher in alpine grassland compared to beech forest and whether stoats are likely to be a frequent predator of ground nests in alpine grasslands relative to other introduced mammals that inhabit them. If nest survival is higher in alpine grassland then alpine grasslands may be a refuge from predation. However, if it is not then it is important for management to know the relative risk posed by stoats compared with other predators. An artificial nest experiment was used to answer these questions. This research was undertaken during two years of low to intermediate beech seedfall and therefore provided an opportunity to look at the ecology of stoats in a New Zealand National Park outside years of peak abundance. The principal study site for this research was the Borland Valley, Fiordland National Park. Compositional analysis showed that stoats in alpine grassland selected for it over adjacent beech forest. The range cores of these stoats were high up in alpine grassland away from the ecotone with beech forest. Stoats occurred at similar densities in alpine grasslands as they did in beech forest and observed survival was similar between the two habitats (with the exception of 2004 when it may have been higher in alpine grassland). The most frequent prey of stoats inhabiting beech forest were birds and mice. Although stoats in alpine grasslands also ate birds and mice their most frequent prey were ground weta and hare. Food addition appeared to cause diet switching but did not reduce the distances moved by stoats, suggesting that other factors may be more important in regulating their summer home range size in alpine grasslands. All of these factors lead to the conclusion that alpine grasslands in the Borland are not a marginal habitat for stoats, but may instead be a desirable one. Artificial nests had a higher probability of survival in alpine grassland compared to adjacent beech forest, but survival was too low to support the idea that alpine grasslands are a refuge. Stoats were the most frequent predator of artificial nests in both habitats, but 95 % confidence intervals overlapped the predation rate by possums, which was also high. These findings illustrate the need for a comprehensive landscape approach to stoat control in montane National Parks, for two reasons: 1) endemic biodiversity in alpine grasslands may be under threat from stoat predation, 2) alpine grasslands may act as a source for dispersing stoats that reinvade lowland stoat control areas. In the absence of heavy beech seedfall and peak mouse abundance, stoats occurred at densities of around 1 km⁻� in both habitats and there was recruitment into these populations. This raises the important question: What regulates the distribution and abundance of stoats in years of low beech seedfall and low mouse abundance? In these years birds, ground weta and hares may be as important as mice are in years of peak abundance following heavy beech seedfall.

Alpine ecosystems have undergone significant modifications in recent years due to climate change. A trend towards reduced summer rainfall has been detected in various mountain regions, with warm, dry conditions predicted to intensify in some areas of the Alps by the end of the century. Together with increased frequency and magnitude of extreme events, new questions arise as to how climate change will impact ecosystem stability and functions. Although a number of studies have addressed the effects of warming on alpine ecosystems, responses to drier conditions remain poorly investigated. The main objective of the present research was to assess the effects of summer warming and reduced precipitation on key ecosystem functions of an alpine Carex curvula grassland over a 3-year period, with both field and lab experiments. The first field experiment investigated biomass production (Study 1) and litter decomposition (Study 2) in response to summer warming and chronic press drought. Increased temperatures were simulated using open top chambers, with rain-out shelters simulating historically-based, site-specific drought. Study 1 focused on the extent to which above- and belowground net primary production (ANPP and BNPP) were affected by treatments over 2 years; inter-annual ANPP differences, including the pre-treatment year, were also analysed. Results reveal that treatments do not influence ANPP, although there is wide inter-annual variation, whereas BNPP is lower under shelters. ANPP reveals a certain degree of resistance to short-term warming and extreme drought, but the difference between ANPP and BNPP underlines the need to take both compartments into account when assessing climate change effects on plant production. In Study 2, litter decomposition responses to treatments were analysed during one year (fall 2018-2019), with the influence of seasonality on litter quantity and quality also investigated to estimate the contribution of the long snow-covered season on the stability of decomposition processes under altered summer conditions. Standard litter (teabags) was employed in treatments, whereas native litter was used to assess the variability of litter quality and verify the degree to which native litter dynamics are reflected by standard litter. Despite more favourable growing season climate conditions, summer decomposition is limited by end-of-winter litter alteration, suggesting that early decomposition in alpine ecosystems remains stable even under altered summer conditions. Two further experiments (Study 3 and 4) investigated the extent to which ANPP and CO2 fluxes – ecosystem respiration (ER), gross ecosystem production (GEP) and net ecosystem exchange (NEE) – are affected by acute pulse dry spells during early- and mid-growing season. Study 3 assessed the role of drought timing on grassland monoliths in a mesocosm, with a full-season drought treatment also implemented to detect the soil moisture and temporal thresholds triggering changes in ER and GEP. Results indicate that ANPP and CO2 fluxes are negatively influenced by drought, the extent varying according to its timing and duration; thresholds for ER and GEP differ between drought timings, those during the mid-season being reached earlier and at higher moisture content, which underlies the importance of extreme event timing. Study 4 consisted of a single-season field replication of Study 3, with results showing that the grassland is resistant to pulse drought in the short-term, with stable ANPP and NEE responses. In the field, however, high soil moisture levels never reached the thresholds detected in the mesocosm study, highlighting the need for field experiments, which are carried out in more complex, natural conditions, in order to confirm findings from controlled studies. Overall, the present research reveals that key ecosystem processes in representative alpine grasslands are resistant to short-term press drought, but are vulnerable to pulse drought events.<br>Nelle ultime decadi, gli ecosistemi alpini hanno subito importanti alterazioni dovute ai cambiamenti climatici che, in diverse aree montuose, hanno comportato non solo un aumento delle temperature ma anche una riduzione delle precipitazioni. Inoltre, l’aumento della frequenza e intensità degli eventi estremi rende urgente la necessità di comprendere l’impatto di tali eventi sulla funzionalità degli ecosistemi. Per i sistemi alpini sono molteplici gli studi sulle risposte ecologiche al riscaldamento, mentre scarseggiano le ricerche sugli effetti di un clima più secco. In questo quadro si sviluppa la presente ricerca, basta su esperimenti in campo e in laboratorio volti a valutare le risposte ecologiche di una prateria alpina a Carex curvula a cambiamenti di temperatura e precipitazioni. Le risposte della produzione primaria (Studio 1) e della decomposizione (Studio 2) sono state valutate tramite manipolazioni sperimentali, effettuate nel periodo libero dalla neve, della temperatura, tramite Open Top Chambers, e delle precipitazioni, per mezzo di tettoie ad esclusione parziale della pioggia simulanti un estremo climatico sito-specifico. Lo Studio 1 ha valutato la risposta della produzione primaria epigea (ANPP) e ipogea (BNPP) a 2 anni di trattamento (2018-19), analizzando anche la variazione inter-annuale della ANPP. Dai risultati non è emerso alcun effetto dei trattamenti sulla ANPP, che ha invece esibito significative variazioni inter-annuali, mentre la BNPP è risultata inferiore sotto le tettoie. Complessivamente, la prateria sembra resistente al riscaldamento e alla riduzione estrema delle precipitazioni nel breve termine, sebbene le differenze nelle risposte tra ANPP e BNPP evidenzino la necessità di considerarle entrambe nelle indagini sulla produzione primaria in risposta ai cambiamenti climatici. Analogamente allo Studio 1, i processi di decomposizione analizzati nello Studio 2 utilizzando lettiera standard (teabags) non sono stati influenzati dai trattamenti estivi, probabilmente a causa dell’alterazione invernale della lettiera. L’uso della lettiera nativa nei controlli nel medesimo studio ha, inoltre, permesso di determinare il grado di variabilità naturale della qualità della lettiera e verificare quanto le dinamiche di decomposizione della lettiera standard riflettano quelle della lettiera locale. Ulteriori esperimenti sono stati condotti sia in mesocosmo (Studio 3) sia in campo (Studio 4) al fine di valutare la risposta della ANPP e dei flussi di CO2 – respirazione ecosistemica (ER), assimilazione ecosistemica lorda (GEP) e netta (NEE) – rispetto alla tempistica degli eventi siccitosi, i.e. periodi di assenza di precipitazioni acuti sperimentati in diverse fasi della stagione vegetativa. In entrambi gli studi, oltre a un trattamento di siccità applicato nella prima e seconda parte dell’estate (ED e MD), è stato imposto un ulteriore trattamento lungo l’intera stagione (FD) per stimare le soglie di umidità determinanti una brusca variazione dei tassi di ER e GEP. Nello Studio 3, sia ANPP sia i flussi di CO2 sono stati negativamente impattati dalla siccità in una misura diversa a seconda della durata e del periodo di incidenza del secco. Le soglie per ER e GEP sono inoltre risultate diverse tra MD e ED, con le soglie in MD raggiunte prima e a umidità maggiori rispetto a quelle in ED. Contrariamente a quanto osservato nel mesocosmo, nello Studio 4 la ANPP e i flussi di CO2 sono risultati stabili rispetto ai trattamenti e l’umidità del suolo non ha mai raggiunto le soglie identificate in laboratorio, evidenziando così la necessità di affiancare a studi controllati ulteriori esperimenti in condizioni naturali e più complesse. Concludendo, la presente ricerca rivela come i principali processi ecosistemici di una prateria alpina siano resistenti nel breve periodo al riscaldamento e a una riduzione cronica delle precipitazioni, ma siano potenzialmente vulnerabili a eventi acuti di secco.

In the Italian Alps, summer pastures are still managed in traditional ways, which maintain important grassland habitats of many species, although the number of pastures has declined drastically over the past few decades. Research on alpine pastures is important in many respects. From the aspect of nature protection, pastures represent a habitat for numerous plant and animal species; and, through their diversity, contribute greatly to the biodiversity and scenic value of the area. From the economic standpoint, grasslands are a source of feed for stock, a habitat for medicinal and melliferous plants. They are also capable of supporting particular dairy products, high added value, because fodder obtained from natural with unique qualities and not reproducible, capable of giving products derived valuable characteristics and identification. Land use changes constitute a threat to the persistence of these grassland ecosystems Therefore, it is very important to understand the mechanisms leading to the organization and distribution of these communities to preserve plant diversity and to develop effective agri-environment schemes, which can maintain and enhance biodiversity. Phytosociological investigation is important to understand some aspects of the study of grasslands. As in the forestry sector, also in grasslands sector have arisen in recent years some efforts to characterize, according to a typological approach, pasture vegetation. A purpose of this research was to realize an interpretative classification of pastures of Province of Trento. Since the pastures of the study area have not been systematically investigated for a long time, the pasture vegetation of the Province of Trento was classified using numerical methods, then the results were compared with the traditional syntaxonomic system, and finally were examined the influence of ecological factors on variation in grassland vegetation. Further aim of the research was assessed the relationship between topography, distance from the farm centre, altitude, bedrock, grazing intensity, species richness and vegetation composition across two spatial scales (within and between summer farms). A stratified random sampling design was used to collect 157 vegetation relevés along an elevation gradient. It was hypothesized that plant diversity varies in response to topography due to the highly variable alpine environment and it depends strongly not only on grazing spatial gradient from the centres of the farms to the surrounding vegetation, but also on spatial distribution of the management practices within the study region The patterns of species richness and species composition found in alpine pastures result from the interaction of different environmental and management factors operating at different spatial scales. The results indicate that at small scales (within farms) species richness is mainly determined by slope, while specie composition is controlled by distance from the farm centre as well as slope. At large scale (between farms), was observed a key role of grazing intensity and bedrock types on species diversity patterns. The results indicate that the identification of appropriate stocking rates appears to be the most promising approach to conserve the high biodiversity of alpine pastures, as both intensification and abandonment changed species composition and reduced plant species diversity. Finally, to gain insight into the processes that may affect species diversity and functional diversity in alpine pastures, the observed local patterns of additive species diversity components (α-, β-, γ-) were analysed with respect to altitude, landscape, topographic hetereogeneity, bedrock type and grazing intensity. Additive diversity partitioning approach facilitated a quantification and comparison of the relative contributions of α- and β-diversity components to total regional diversity along an elevation gradient. Based on the results, I conclude that the observed patterns of plant species diversity appeared to be influenced by processes at multiple spatial scales. The results indicate that the maintenance of a large variety of grassland utilisation systems along with heterogeneous abiotic environmental conditions appears to be a promising tool for the conservation of species richness and functional diversity due to enhanced β-diversity among pastures parcels.<br>Nelle Alpi italiane, gli alpeggi sono ancora gestiti in maniera tradizionale, conservando importanti habitat e specie vegetali, sebbene il numero delle malghe monticate sia diminuito drasticamente negli ultimi decenni. La ricerca sui pascoli alpini è importante sotto molti aspetti. Dal punto di vista della protezione della natura, i pascoli rappresentano l'habitat di numerose specie vegetali ed animali e attraverso la loro ricchezza di specie, contribuiscono notevolmente alla biodiversità ed al valore paesaggistico delle Alpi. Dal punto di vista economico, i pascoli sono una fonte di alimentazione per gli animali, ed habitat per piante officinali e mellifere. Sono anche in grado di supportare prodotti lattiero-casearii particolari, ad alto valore aggiunto, perché ottenuti da foraggi naturali con caratteristiche uniche e non riproducibili, in grado di dare prodotti derivati di qualità. I cambiamenti di uso del suolo costituiscono una minaccia per la persistenza di questi ecosistemi. Pertanto, è molto importante comprendere i meccanismi che controllano l'organizzazione e la distribuzione di queste comunità, per preservare la diversità delle piante e di sviluppare efficaci schemi agro-ambientali, in grado di mantenere e migliorare la biodiversità. L’analisi fitosociologia è importante per comprendere alcuni aspetti dello studio delle praterie. Come nel settore forestale, anche in quello pastorale sono iniziati negli ultimi anni alcuni progetti per caratterizzare, secondo un approccio tipologico, le vegetazioni pascolive. Uno degli obiettivi di questa ricerca era quello di realizzare una classificazione interpretativa dei pascoli della Provincia di Trento. Poiché i pascoli della zona oggetto di studio non sono mai stati studiati in modo sistematico, la vegetazione dei pascoli della Provincia di Trento è stata classificata utilizzando metodi numerici; i risultati sono stati confrontati con il sistema tradizionale sintassonomico e, infine, è stata analizzata l'influenza dei fattori ecologici sulla variazione della composizione floristica dei pascoli. Un successivo obiettivo della ricerca era quello di valutare la relazione tra la topografia, la distanza dal centro aziendale, l'altitudine, il tipo di substrato geologico, l’intensità di pascolamento, la ricchezza di specie e la composizione della vegetazione attraverso due scale spaziali (all'interno e tra le malghe campionate). Un disegno sperimentale stratificato è stato utilizzato per campionare i 157 rilievi vegetazionali lungo un gradiente altitudinale. E’ stato ipotizzato che la diversità vegetale varia in risposta della topografia legata all'ampia variabilità ambientale degli ambienti alpini, e dipende in modo consistente non solo dal gradiente spaziale di pascolamento dal centro della malga alle vegetazioni marginali, ma anche dalla distribuzione spaziale delle pratiche gestionali impiegate nell’area di studio. I modelli di distribuzione della ricchezza di specie e della composizione riscontrati nei pascoli alpini derivano dall'interazione di diversi fattori ambientali e gestionali che operano a diverse scale spaziali. I risultati indicano che su piccola scala (all’interno delle malghe), la ricchezza di specie è principalmente controllata dalla pendenza, mentre la composizione vegetazionale è determinata dalla distanza dal centro della malga, e dalla pendenza. Su larga scala (tra le malghe), è stato osservato un ruolo chiave dell’intensità di pascolamento e del tipo di substrato geologico sulla ricchezza di specie. I risultati indicano che l'individuazione di appropriati indici di carico animale sembra essere l'approccio più promettente per la conservazione della biodiversità dei pascoli alpini, poiché, sia l’intensificazione gestionale che l’abbandono cambiano composizione delle specie e riducono la diversità delle specie vegetali. Infine, al fine di conoscere i processi che possono influenzare la diversità delle specie e, la diversità funzionale nei pascoli alpini, i diversi componenti additivi della biodiversità (diversità -α, -β e -γ) sono stati analizzati in relazione all'altitudine, alle variabili del paesaggio, dell’eterogeneità topografica, del tipo di substrato geologico e l'intensità di pascolamento. L’approccio della partizione additiva della diversità facilita la quantificazione ed il confronto tra i contributi relativi delle componenti -α-e –β della diversità rispetto al totale delle diversità regionale lungo un gradiente altitudinale. Sulla base dei risultati ottenuti, è stato osservato che la diversità vegetale sembra essere influenzato dai processi operanti a differenti scale spaziali. I risultati indicano che il mantenimento di una grande varietà di tipi gestionali, insieme alle condizioni ambientali eterogenee delle zone alpine sembra essere uno degli strumenti più favorevoli per la conservazione delle ricchezza di specie e della diversità funzionale, contribuendo ad aumentare la diversità β tra i pascoli.

Les espaces proteges francais (parcs nationaux) sont demandeurs de methode d'inventaire des milieux naturels sur de grandes superficies (superieures a 50 000 ha) pour, notamment, gerer les alpages. L'objectif de cette these est de rechercher une methode de cartographie des milieux naturels du parc national des ecrins par teledetection. L'application s'interesse essentiellement a discriminer les formes vegetales du domaine supraforestier sur des images satellitaires spot et landsat tm. La demarche est basee sur une double approche: 1/ agroecologie pour une description precise des espaces pastoraux, 2/ teledetection pour les identifier de maniere spatiale. Les descripteurs communs a ces deux entrees portent sur la physionomie de la vegetation. Il en resulte une typologie physionomique (14 types), spatialisee par les techniques de classification dirigee. Sur les images classees obtenues par pixel, dont on analyse l'heterogeneite spatiale et thematique, on procede a un decoupage de l'espace en unites physionomiques. Les traitements en zone a fortes contraintes (relief marque et mosaique de vegetation) necessitent des corrections geometriques prealables (precision de 1 a 2 pixels) et plusieurs etapes de controles pour verifier leur pertinence ecologique et proposer une validation quantifiee des resultats (environ 70% de correspondances satisfaisantes entre les unites cartographiees et la realite de terrain). Ces resultats permettent de repondre a des besoins de cartographie ecologique a moyenne echelle (1:25 000, correspondances avec les nomenclatures europeennes). Obtenus sur les ecrins, ils contribuent a enrichir la reflexion methodologique en proposant des traitements d'images adaptes aux zones heterogenes de montagne (emploi de descripteurs physionomiques) et une demarche reproductible (double approche construite avec un modele ecologique et un outil de spatialisation de l'information)

Nous abordons une description ecologique et une interpretation phytosociologique des paturages de la vallee du chazelet. Une comparaison bibliographique avec diverses monographies placees dans les alpes internes francaises nous permet de placer notre territoire dans un contexte biogeographique plus general. En relation avec l'activite agricole (fauchage et paturage), nous determinons les potentialites fourrageres des pelouses selon leur appartenance phytosociologique. Une cartographie illustre ce point en vue d'une gestion rentable mais preservatrice des alpages. Enfin, l'utilisation simultanee de deux modes d'echantillonage de la vegetation nous a permis de realiser une comparaison methodologique pour l'estimation des qualites pastorales d'une pelouse

Le charbon de bois (biochar), est un amendement qui améliore les propriétés physico-chimiques du sol, augmente le stockage du carbone et les productions agricoles. Les anciens sites de production de charbon permettent d'évaluer son impact directement sur le terrain et sur le long terme. Dans les Alpes italiennes on a échantillonné une série de charbonnières daté de 1858 ainsi que les sols de prairies adjacents, ne contenant pas de charbon. 80±21% du carbone provenant de la production du charbon est toujours présent dans le sol et a un temps de résidence moyen de 650±139 ans. Le contenu des nutriments et leur biodisponibilité sont plus élevés dans les charbonnières par rapport à la prairie alentour et, sont plus élevés aujourd'hui qu'en 1858. L'ajout de charbon apporte des nutriments au sol, mais à court terme les ions Ca2+, K+, SO42- et Mg2+ sont lixiviés sous forme de cendres. Le charbon s'avère capable de retenir les dépositions atmosphériques de PO43-, NH4+, NO3- et, sur le long terme, de K+. L'augmentation du contenu en nutriments, la diminution de l'hydrophobie et de la densité apparente du sol augmentent la productivité et la valeur nutritionnelle des espèces alpines fourragères (Festuca nugrescens Lam. et Trifolium pratense L.). La croissance des plantes est limitée par l'azote sur les charbonnière et par le phosphore dans les prairies non-amendés ou amendés récemment. Nous concluons que le charbon/biochar peut être une stratégie pour stocker le carbone dans les sols, augmenter la production de biomasse et la qualité du fourrage des prairies Alpines à long terme. Toutefois les opérations d'enfouissement peuvent être complexes à cause de la géomorphologie des Alpes<br>Charcoal or biochar is proposed as a soil amendment to improve physio-chemical soil properties, increase soil carbon (C) stocks and agricultural yields. Ancient charcoal hearths provide an opportunity to investigate its impact under field conditions and in the long term. A series of charcoal hearths and adjacent charcoal-free soils under grassland in the Italian Alps abandoned in 1858 was sampled.80±21% of the C originating from ancient charcoal is still present in the soil today and has a Mean Residence Time of 650±139 years. The content of total and available nutrients is higher in the hearths soils compared to the surrounding grasslands and it is higher today compared to 1858. The input of charcoal directly adds nutrients to soils but Ca2+, K+, SO42- and Mg2+ are leached in the short term after application, as they are lost in the form of ashes. Charcoal is able to retain atmospheric depositions of PO43-, NH4+, NO3- and in the long term K+.The increase in soil nutrient content and decreases in hydrophobicity and bulk density translated into higher plant growth and nutritional values of two alpine fodder species (Festuca nigrescens Lam. and Trifolium pratense L.). Plant growth was N-limited in the charcoal hearths soils and P-limited in the surrounding grasslands not amended or recently amended with charcoal/biochar.We can conclude that charcoal/biochar is a long term strategy to store carbon in soils, improve biomass productivity and fodder quality in alpine grasslands. However charcoal/biochar incorporation into soil can be complex because of the geomorphology of the Alps

The purpose of this thesis was to classify and describe low-elevation grassland and shrubland vegetation, mid-elevation woodland and forested vegetation, and high elevation alpine vegetation associations of the Beartooth Mountains study area and to compare newly derived associations with existing habitat type and community type classifications of ecologically relevant environments in Montana, Wyoming and Idaho. Five grassland/shrubland associations, twelve woodland/forested associations and thirteen alpine associations were classified and described for the Beartooth Mountains study area. Prior to this thesis, no comprehensive vegetation association classification of the Beartooth Mountains, the highest, largest and easternmost alpine region in Montana, has been conducted. 'Co-authored by Dave W. Roberts.'

Les alpages laitiers des alpes du nord externes (france) representent un type de systeme ecologique original refletant les effets des pratiques d'eleveurs (fertilisation, paturage) combines aux contraintes du milieu montagnard (etage subalpin). Face aux mutations recentes des modes d'exploitation des alpages, des recherches ont ete engagees pour comprendre et prevoir l'impact des pratiques pastorales sur la dynamique de ces pelouses d'altitude. Nous proposons un modele d'evolution de la composition botanique qui integre l'effet des facteurs anthropiques et celui des facteurs edaphiques. Ce modele s'appuie sur une analyse factorielle des correspondances portant sur un echantillonnage de six cent releves floristiques couvrant l'ensemble de la zone d'etude. La reconstitution des trajectoires dynamiques se fait principalement par une approche synchronique, completee par des observations diachroniques qui ont permis de preciser les vitesses d'evolution de la vegetation. L'essentiel des travaux porte sur des situations de deprise: la dynamique de la vegetation y reflete une degradation de la fertilite des sols consecutive a l'abandon ou a l'allegement de la fertilisation. Cette evolution est generalement lente: deux a cinq decennies sont necessaires pour que l'on enregistre des changements notables dans la composition botanique. Les resultats mettent egalement en evidence l'influence des parametres edaphiques sur les limites et le deroulement de ces successions. Les modalites d'evolution de la vegetation et la hierarchie des facteurs sont precisees dans des trajectoires-types qui permettent d'adapter localement la demarche de diagnostic ecologique. Differents indicateurs, relatifs aux processus physiologiques ou demographiques d'evolution de la vegetation, sont testes afin de preciser ou d'anticiper le diagnostic floristique. Les indices de diversite specifique ou factorielle restent d'un usage delicat en raison de leur sensibilite a l'egard des methodes d'echantillonnage et d'observation. Les indices de nutrition minerale font rapidement apparaitre les modifications d'equilibres trophiques qui suivent l'arret ou la reprise de la fertilisation

The Bogong High Plains are a series of alpine and subalpine plateaux in NE Victoria. The vegetation of the High Plains consists of woodland, heathland, grassland herbfield and wetland communities. On the better drained sites, the transition from heath dominated communities to grass dominated communities is correlated with gradients of decreasing accumulation and persistence of snow, increasing exposure to wind and low minimum air temperatures, and decreasing steepness and rockiness of terrain. In many areas, shrubs have increased in cover and abundance, especially over the last 50 years. In particular, shrubs have invaded many areas of grassland, which has resulted in an expansion of both open heath and closed heath. The High Plains have been grazed by free ranging cattle each summer since the 1850's, and a primary aim of this thesis is to investigate the dynamics of heathland and grassland, and the impact that cattle grazing has upon these two vegetation types.

Le charbon de bois (biochar), est un amendement qui améliore les propriétés physico-chimiques du sol, augmente le stockage du carbone et les productions agricoles. Les anciens sites de production de charbon permettent d'évaluer son impact directement sur le terrain et sur le long terme. Dans les Alpes italiennes on a échantillonné une série de charbonnières daté de 1858 ainsi que les sols de prairies adjacents, ne contenant pas de charbon. 80±21% du carbone provenant de la production du charbon est toujours présent dans le sol et a un temps de résidence moyen de 650±139 ans. Le contenu des nutriments et leur biodisponibilité sont plus élevés dans les charbonnières par rapport à la prairie alentour et, sont plus élevés aujourd'hui qu'en 1858. L'ajout de charbon apporte des nutriments au sol, mais à court terme les ions Ca2+, K+, SO42- et Mg2+ sont lixiviés sous forme de cendres. Le charbon s'avère capable de retenir les dépositions atmosphériques de PO43-, NH4+, NO3- et, sur le long terme, de K+. L'augmentation du contenu en nutriments, la diminution de l'hydrophobie et de la densité apparente du sol augmentent la productivité et la valeur nutritionnelle des espèces alpines fourragères (Festuca nugrescens Lam. et Trifolium pratense L.). La croissance des plantes est limitée par l'azote sur les charbonnière et par le phosphore dans les prairies non-amendés ou amendés récemment. Nous concluons que le charbon/biochar peut être une stratégie pour stocker le carbone dans les sols, augmenter la production de biomasse et la qualité du fourrage des prairies Alpines à long terme. Toutefois les opérations d'enfouissement peuvent être complexes à cause de la géomorphologie des Alpes<br>Charcoal or biochar is proposed as a soil amendment to improve physio-chemical soil properties, increase soil carbon (C) stocks and agricultural yields. Ancient charcoal hearths provide an opportunity to investigate its impact under field conditions and in the long term. A series of charcoal hearths and adjacent charcoal-free soils under grassland in the Italian Alps abandoned in 1858 was sampled.80±21% of the C originating from ancient charcoal is still present in the soil today and has a Mean Residence Time of 650±139 years. The content of total and available nutrients is higher in the hearths soils compared to the surrounding grasslands and it is higher today compared to 1858. The input of charcoal directly adds nutrients to soils but Ca2+, K+, SO42- and Mg2+ are leached in the short term after application, as they are lost in the form of ashes. Charcoal is able to retain atmospheric depositions of PO43-, NH4+, NO3- and in the long term K+.The increase in soil nutrient content and decreases in hydrophobicity and bulk density translated into higher plant growth and nutritional values of two alpine fodder species (Festuca nigrescens Lam. and Trifolium pratense L.). Plant growth was N-limited in the charcoal hearths soils and P-limited in the surrounding grasslands not amended or recently amended with charcoal/biochar.We can conclude that charcoal/biochar is a long term strategy to store carbon in soils, improve biomass productivity and fodder quality in alpine grasslands. However charcoal/biochar incorporation into soil can be complex because of the geomorphology of the Alps

Les prairies de montagne offrent de nombreux services ecosystémiques qui sont menacés par le changement global. Les traits fonctionnels constituent un outil prometteur pour caractériser les réponses des communautés à des changements de conditions environnementales et leurs répercussions sur les services associés. Cependant, des résulats de plus en plus nombreuses soulignent l’importance de la variabilité intra-spécifique des traits a également été mise en évidence. Pour étudier ces effets, je propose un nouveau modèle à base d’agents, MountGrass, qui combine la modélisation de communautés végétales riches en espèces avec des processus de plasticité phénotypique. Ces deux éléments au coeur du modèle sont associés grâce à des compromis d’allocation basés sur des patrons empiriques établis de stratégies d’utilisation des resources.Avec MountGrass, j’ai exploré l’impact de la plasticité phénotypique sur la croissance individuelle et les propriétés principales des communautés prairiales. À l’échelle individuelle, le modèle paramétré a révélé un fort impact positif de la plasticité phénotypique sur la croissance mais aussi sur la niche fondamentaledes espèces. Des phénomènes de convergence et de réduction de la sensibilité aux variations de conditionsexpliquent ces effets. À l’échelle des communautés, les simulations ont confirmé de forts effets de la plasticité sur la structure des communautés et leur diversité spécifique. Ces effets sont expliqués par l’effet combiné de la réduction du filtre abiotique et de la réduction des différences de compétitivité. Cependant, aucun effet majeur sur la stratégie dominante ou la productivité n’a pu être mis en évidence.Des implémentations alternatives ou des extensions du modèle devraient permettre de tester la robustesse des résultats obtenus et d’analyser d’autres schémas de dynamiques des communautés. En conclusion, ce travail ouvre la voie à une meilleure considération et une meilleure compréhension du rôle des variabilités intra-spécifiques dans les dynamiques des communautés végétales<br>Mountain grasslands provide numerous ecosystem services that are likely to be impacted by global change. Plant functional traits hold great promise to succinctly characterise plant community response to changing environmental conditions and its effect on associated services; with growing evidence of the importance of intra-specific trait variability. I propose here a novel agent-based model, MountGrass, that combines the modelling of species rich grassland communities with phenotypic plasticity. These two key components are integrated via allocation trade-offs based on established empirical patterns of strategic differentiation in resource-use.With MountGrass, I explored the impact of phenotypic plasticity on individual plant growth and on main properties of grassland communities. At the individual level, the parametrised model revealed a strong impact of plasticity on growth and species’ fundamental niches, with potentially large impacts on community properties. These effects are explained by the convergence of species’ strategies and the reduction of the sensitivity to variable conditions. At the community level, simulations confirmed the strong effect of plastic allocation on community structure and species richness. These effects are driven by the cumulative effect of a reduction of both abiotic filtering and fitness differences between species. However, no clear effect on the dominant strategy or productivity could be detected.Going further, the robustness of these findings and other patterns of community dynamics should be analysed with alternative or extended implementations of MountGrass. In sum, this work opens a door towards a better integration and understanding of the role of the intra-specific variability in complex plant community dynamics

碩士<br>國立臺灣師範大學<br>生物學系<br>93<br>Sambar deer (Cervus unicolor) are the largest deer in East-Southern Asia, but very little knowledge about their behavior is known, especially the quantified field data such as behavioral time budget. From April 2003 to December 2004, the behavior of wild Formosan sambar (C. u. swinhoei) was observed on an alpine grassland at Pans Mountain, Central-Northern Taiwan. A total of 459 deer groups were sighted in 796.4 hours and the mean group size of sambar were 1.32deer/group. Sighting rates were significantly higher in summer and fall (0.91±0.49, 1.06±0.58 group/hr) than in spring and winter (0.49±0.32, 0.35±0.27 group/hr), and were highest in early morning (before 8 a.m.) compared to other five daytime periods. Grouping pattern of alpine Sambar has a trend to be solitary or in pairs all the seasons, while male sambar were more solitary than females and fawns. Sambar spent most of their daytime on foraging (61.73%) and less time on resting, ruminating, locomotion and other behavior. Compared to other two age-sex classes, female sambar spent more time on foraging and searching. However, females spent similar time on feeding with males and fawns. For female and fawn, the seasonal changes of foraging rates were not significantly different, but were greater in fall coincided with the rutting season for males. Based on our annual observation, the searching rates of sambar declined from spring to winter for males and females, but not for fawns. Foraging rates of sambar before bedding were significantly greater than the ones after bedding (P<0.001), and were attributed to the higher self-grooming rates after bedding (P<0.05). In spite of age-sex classes, searching rates of sambar were positively correlated with another indicator of food selection, the select index. Therefore, both indicators were representative of food selection for alpine sambar in this study. All three vigilance indicators of sambar were significantly different from each other when considering three sex-age classes of sambar, but only one of them, the intra-scan interval, conformed to our prediction that males were less vigilant than females and fawns because of their large body size and their sex-age-related weapon (antler). Besides, time spent scanning of sambar when foraging on grassland were significantly greater than the those foraging on forest edge, and the result were agreed to our observation about their fleeing response to shelter, the forest. Other biological factors, however, such as group size and composition did not affect the vigilance of sambar, except for an unusual result that the scan rates of females with fawns were lower than those without fawns. Time spent on resting or ruminating of sambar was nearly fifty-fifty after sambar bedded. On the other hand, mean time period of ruminating bout of sambar while bedding were significantly greater than those while standing. Among three sex-age classes of sambar, males spent more time on social behavior, which had a high proportion of marking behavior, than female and fawn. In addition, rubbing with antler was the most common marking behavior for male. Among three distinct sort of self-grooming behaviors of sambar, oral-grooming occurred most often (91.04%), followed by scratch- grooming (8.53％) and antler-grooming (only three times for males). Moreover, males spent less time on self-grooming, which might be reduced by their wallowing behavior with a possible function of removing ectoparasites. Sambar excreted their droppings with a posture of standing (45％) or walking (55％), and the defecation rates for adults were slightly greater than for fawns with a range of 8.16 to 13.92 (bouts/day). The degrees of ear flicking were significantly correlated with ambient temperature in spite of standing or bedding. Anti-predator responses before fleeing caused by observer were classified into tail-flagging (83.33%), snorting (59.52%) and stamping ground with forelegs (26.19%), and more than two of them could occur spontaneously. We classified foraging, locomotion, social and other behaviors as “active” phase and resting and ruminating as “inactive” one of sambar. Therefore, the average relative diurnal activeness of sambar was 72.75%. On this alpine grassland, we believed sambar were more active than on other unstudied habitats. During daytime, the more active hours of sambar were at 10 a.m. and 16 p.m. while less active ones were at 6 a.m., 11 a.m., and 17 p.m. Furthermore, relative diurnal activeness was lower in winter and summer than other two seasons, but no differences were detected between sunny and cloudy days in our analysis.

abstract: The plateau pika (Ochotona curzoniae), a small burrowing lagomorph that occupies the high alpine grassland ecosystems of the Qinghai-Tibetan Plateau in western China, remains a controversial subject among policymakers and researchers. One line of evidence points to pikas being a pest, which has led to massive attempts to eradicate pika populations. Another point of view is that pikas are a keystone species and an ecosystem engineer in the grassland ecosystem of the QTP. The pika eradication program raises a difficult ethical and religious dilemma for local pastoralists, and is criticized for not being supported by scientific evidence. Complex interactions between pikas, livestock, and habitat condition are poorly understood. My dissertation research examines underpinning justifications of the pika poisoning program leading to these controversies. I investigated responses of pikas to habitat conditions with field experimental manipulations, and mechanisms of pika population recovery following pika removal. I present policy recommendations based on an environmental ethics framework and findings from the field experiments. After five years of a livestock grazing exclusion experiment and four years of pika monitoring, I found that grazing exclusion resulted in a decline of pika habitat use, which suggests that habitat conditions determine pika population density. I also found that pikas recolonized vacant burrow systems following removal of residents, but that distances travelled by dispersing pikas were extremely short (~50 m). Thus, current pika eradication programs, if allowed to continue, could potentially compromise local populations as well as biodiversity conservation on the QTP. Lethal management of pikas is a narrowly anthropocentric-based form of ecosystem management that has excluded value-pluralism, such as consideration of the intrinsic value of species and the important ecological role played by pikas. These conflicting approaches have led to controversies and policy gridlock. In response, I suggest that the on-going large-scale pika eradication program needs reconsideration. Moderation of stocking rates is required in degraded pika habitats, and Integrated Pest Management may be required when high stocking rate and high pika density coexist. A moderate level of livestock and pika density can be consistent with maintaining the integrity and sustainability of the QTP alpine steppe ecosystem.<br>Dissertation/Thesis<br>Doctoral Dissertation Biology 2016

Hlogoma Mountain is a small inselberg surrounded by farms and commercial forestry in the Underberg district (KwaZulu-Natal) within the Gs10 Drakensberg Foothill Moist Grassland. As little is known about the vegetation on Hlogoma, a survey was undertaken to classify, map and describe the plant communities occurring on the inselberg. A total of 100 (16 m2) randomly stratified sample plots were placed in homogeneous vegetation units within the 117 ha study area. A TWINSPAN classification, refined by Braun-Blanquet procedures, resulted in the identification of two major communities, five communities, 12 sub-communities and four variants. All communities were described and a vegetation map constructed. Ordinations identified key environmental variables that have an impact on the vegetation at the study site. A plant species checklist was created and analysed for floristic composition; rarity and threatened species; medicinal plants; endemism; phenology; flower colour and elevation range; species richness and plant community biodiversity. A total of 467 species were identified, represented by 271 genera and 87 families. Four Red Data species and a new Aspidoglossum species were discovered. Two near-endemic genera, two endemic species and 88 near-endemic species belonging to the Drakensberg Alpine Centre were found on Hlogoma. This study showed that Hlogoma Mountain is an inselberg with high plant species richness and endemism, and is a refuge of conservation importance for biodiversity.<br>Environmental Sciences<br>M. Sc.(Environmental Science)