A thesis submi.tted to the Faculty of Science, University of the witwatersrand, Johannesburg I in the fulfillmen,,;"o:f' 't\ :he requirements of the Degree of Magister Scienta~. June 1992 / The present study was undertaken; withirl the South African " savannas, to provide "insight into a j;unctional classification of aavanna plants using ecophY$iologiLcal charact~:t's.THe pri.mary r.:>bjective of this study Was to investigate the vari.ation of these tt'aits throughout: the savanna, aridto relate this variation to plant avail.able moisture and nU~l'ie~~s• !t was conclu.ded that~ 1) no formal or specialized strategies have evolved within a number of the study sites, .2) unlike the woody component I neither divergellce nor convergence was demonstrated within the grass layer, c' 3) plant aVailable nutrients did not appear to be a major determinant of either component. Although plant available moistur~ proved to be unimportant in the woody layer, it did playa role as a determinant of the grass layer, and 4) constancy of the plant traits was not demonstrated to \": OCCllr over the gr~~ing season. A succeisf',\lclassification' would require the components to be separat~pl specific determinan.ts be identified for each component, and an element of time be included into both edaphic and biotic measurements.

O objetivo principal deste trabalho foi identificar os principais fatores abióticos e bióticos correlacionados com a distribuição da abundância e riqueza de hemiepífitos primários, secundários e lianas rizo-escandentes, sinúsias que carecem de estudos, em um gradiente altitudinal na Floresta Atlântica sul-brasileira. Alocamos 15 unidades amostrais no total (de 400 m2 cada), distribuídas nas porções inferior (200 - 250 m a.n.m.), média (380 - 430 m) e superior (670 - 720 m) de um gradiente altitudinal no nordeste do Rio Grande do Sul. Amostramos em cada parcela a abundância de cada espécie, a porcentagem de árvores colonizadas por cada sinúsia e as seguintes variáveis explanatórias: abertura do dossel, composição do solo e densidade de árvores com DAP ≥ 5 e 20 cm; e para cada cota altitudinal, a temperatura e precipitação média anual. Utilizamos modelos lineares generalizados para analisar a influência das variáveis na abundância das sinúsias. Encontramos que as variáveis climáticas (precipitação e temperatura) foram as principais variáveis explanatórias relacionadas com variação na abundância e riqueza das três sinúsias analisadas. As distintas formas de vida apresentaram diferenças na intensidade da resposta às variáveis. Foi registrado um aumento de quatro vezes na abundância de hemiepífitos secundários e de praticamente duas vezes para lianas rizo-escandentes, entre a porção inferior e a superior do gradiente, correlacionando-se positivamente com o aumento da precipitação e umidade. A riqueza total de espécies apresentou um decréscimo na porção superior do gradiente, que foi correlacionado ao decréscimo da temperatura. Os resultados encontrados corroboram trabalhos anteriores, com outros grupos vegetais e animais, que afirmam que as variáveis climáticas são as preditoras de primeira ordem da distribuição das espécies e reforçam a necessidade de se analisar distintas formas de vida, pois estas tendem a responder de modo distinto aos fatores ambientais. / The main aim of this study was to analyze the major abiotic and biotic factors correlated with distribution, abundance and richness of primary and secondary hemiepiphytes and root-climbing lianas along an altitudinal gradient of the South Brazilian Atlantic Forest. Fifteen 400-m² square sample plots within three altitudinal levels at the slope of Serra Geral in north-eastern Rio Grande do Sul were defined. Abundance of all species, the percentage of host trees colonized by each synusia, and explanatory variables canopy openness, soil composition and tree density with DBH ≥ 5 and ≥ 20 cm were recorded for each sample plot. Mean annual air temperature and rainfall were recorded for each altitudinal level. Climatic variables (precipitation and temperature) were the main explanatory variables related with the variation in abundance and richness in the three synusiae studied. The three life forms showed different intensities in their response to these variables. The abundance of secondary hemiepiphytes increased up to four times from the lower to upper altitudinal levels, while root-climbing lianas increased almost twice in the same direction, following an increase in precipitation and humidity. Total species richness decreased toward the upper level of the gradient correlated with lower temperatures and colder winter months. Our results corroborate previous studies on other taxonomic groups, which indicate that climatic variables are first-order predictors for species distribution and reinforce the importance to study different life forms, because these may respond in distinct ways to environment factors.

The Darlingtonia fens, found on serpentine soils in southern Oregon, are distinct communities that frequently undergo dramatic changes in size and shape in response to a wide array of environmental factors. Since few systems demonstrate a balance among high water tables, shallow soils, the presence of heavy metals, and limited nutrients, conservative efforts have been made to preserve them. This dissertation investigates the role of fire on nutrient cycling and succession in three separate fens, each a different time since fire. I specifically analyze the spatial distributions of soil properties, the physical and ecological characteristics of ecotones between Jeffrey pine savanna and Darlingtonia fens, and the vegetation structure of fire-disturbed systems. Soil, water, and vegetation sampling were conducted along an array of transects, oriented perpendicular to community boundaries and main environmental gradients, at each of the three fens. Abrupt changes in vegetation, across communities, were consistently identified at each of the three sites, although statistical analysis did not always identify distinct mid-canopy communities. Below-ground variables were likewise distinguished at the fen and savanna boundary for two of the three sites. At the third site, discontinuities did not align with the fen boundaries, but followed fluctuations in soil NH4. My results suggest that below-ground discontinuities may be more important than fire at preserving these uniquely-adapted systems, while vegetation undergoes postfire succession from fen to mid-canopy to savanna after approximately 100 years since fire. Although restoration of ecosystem structure and processes was not the primary focus of this study, my data suggest that time since fire may drive ecosystem processes in a trajectory away from the normal succession cycle. Moreover, time since fire may decrease overall vigor of Darlingtonia populations.

Vegetation science, like any science, uses classification to organize knowledge about plants and plant communities. Classification is helpful for understanding how different plant communities relate to one another and their environments, for facilitating further studies of vegetation, and for conservation. To familiarize onself with vegetation of a large area, it is very convenient and efficient to begin with a few general units, such as plant orders rather than with many very detailed units, such as plant associations and subassociation. We offer such an approach and think that the information given in this series will be sufficient to assign any forested coastal community to one the orders or suborders. In spite of a history of vegetation studies in British Columbia, there has not yet been any attempt to develop a comprehensive hierarchical classification of plant communities for the province. As the culmination of fifty years of detailed surveys carried out by V.J. Krajina and his students, the Ecology Program Staff of the BC Forest Service, and other workers, we used tabular and multivariate analyses of 3,779 sample plots established in natural, old-growth, submontane, montane, and subalpine forest communities in coastal BC to develop a hierarchy of vegetation units according to the methods of biogeoclimatic ecosystem classification.

This thesis seeks to explain how site-scale design decisions can assist retention of rare plant communities concentrated in and near settled areas. To do so it focuses on a specific species and development context. Explanations are sought through examination of case studies of landuse developments in proximity to retained Garry oak plant communities located in the perimeter of Victoria, British Columbia. In the study region, exponential declines in species populations, health, and diversity of rare Garry oak ecosystems have been largely attributed to impacts from land-use developments. Over the past century, land-use developments have transformed the floral, spatial, structural and functional characteristics of the settled landscape. Isolated islands of imperiled plant associations remain on protected bioreserves: for recruitment and connectivity, these rare fauna rely on private-land greenways. Architectural teams have the potential to influence the decision-making processes that create ecologically-vital greenspace on private land, thereby enhancing survival for declining plant communities. Case-study evidence for the importance of land-use decisions on diminishing Garry oak meadow is gathered through vegetation surveys conducted on Garry oak meadow in proximity to six architectural projects on Victoria's western edge. Observed changes in growth extensions are then categorized in relation to human activities associated with built form, and correlated with principles from Landscape Ecology. An ARC of design strategies, developed in primary research by K. D. Rothley is adapted for architectural use as follows: firstly, AREA of a plant community is kept free of encroachment by the orderly frame established around vegetation; secondly, RARE SPECIES and habitat are identified with borders or signage; thirdly, CONNECTIVITY between retained landscapes is secured by siting roads and buildings to minimize ecosystem fragmentation. To effectively communicate preexisting landscape ecology principles, grouped under the ARC of strategies, illustrations and key-word phrases are developed. These principles, when integrated into architectural teams' structural knowledge, extend the architects' perceived role beyond aesthetics and economic efficiency. Enhancing habitat value through retention or restoration of rare ecosystems at the margins of suburban development, becomes an additional realm of influence for professional teams designing the spatial configurations of peri-urban landscapes.

Habitat fragmentation and biological invasions are widely considered to be the most significant threats to global biodiversity, and synergistic interactions between these processes have the potential to cause even greater biodiversity loss than either acting alone. The objective of my study was to investigate the effects of fragmentation on plant communities in native forest fragments, and to examine potential interactions between these effects and invasions by exotic plants at multiple spatial scales. I examined edge, area and landscape effects on plant invasions using empirical data from fragmented landscapes on the West Coast of New Zealand. My research revealed significant interactions between the amount of native forest cover in the landscape and the strength of edge and area effects on plant communities in forest fragments. The dominance of exotic plants in the community was highest at forest edges and decreased towards fragment interiors, however the interiors of very small fragments were relatively more invaded by exotic plants than those in larger fragments, reflecting a significant interaction between edge and area effects. Similarly, exotic dominance increased in more heavily deforested landscapes, but this effect was only apparent in very small fragments (<2 ha). The combined effects of small fragment size and low forest cover in the landscape appear to have promoted invasions of exotic plants in very small remnants. I explored the mechanisms underlying edge-mediated invasions in forest fragments and examined whether propagule availability and/or habitat suitability may be limiting invasions into fragments. Experimental addition of exotic plant propagules revealed that landscape forest cover interacted with edge effects on germination, growth and flowering rates of two short-lived, herbaceous species, and this appeared to be driven by elevated light and soil phosphorus levels at edges in heavily deforested landscapes. I also examined the role of traits in influencing plant responses to forest fragmentation. Different traits were associated with exotic invasiveness in edge and interior habitats of forest fragments, indicating that the traits promoting invasiveness were context dependent. Traits also had a major influence on responses of native plants to forest fragmentation, with generalist species appearing to benefit from fragmentation, as they can utilise both forest and open habitats, whereas native forest specialists have been negatively impacted by fragmentation.

A monitoring program of forest herbs was initiated at Mammoth Cave National Park (MCNP). The objectives of this project were to produce a quantitative description of the current forest herb communities which can be used as a baseline for monitoring future change as well as a foundation for making informed management decisions. Herbaceous vegetation in previously established permanent forest monitoring plots was characterized during the summers of 1993-94. In the future, these baseline data can be used to detect changes in forest herb communities that might result from natural succession, management decisions and/or environmental changes. The landuse history for these plots was evaluated as a factor affecting the present diversity, richness and cover of the forest herbs at Mammoth Cave National Park. Prior to the establishment of MCNP, landuse consisted of a mosaic of agriculture, logging, and grazing. The park provides unique natural experiment to study the recovery of vegetation following a variety of human influenced disturbances.Thirty-two permanent plots were used to collect species presence and cover in early spring and mid-summer. Five forest herb communities were classified for spring and summer. All plots for the spring and summer community classification were the same except for two. Environmental variables, overstory vegetation, and previous landuse are identified as variables that have significant associations with herbaceous composition. Herbaceous cover, richness, and diversity were higher in areas that were forested before park establishment. The results of this study support the contention that human induced disturbances have more detrimental effect on forest herbs compared to overstory tree species. / Department of Biology

Grassland is an important component of agrarian landscape, performing wide range of ecological, economic and social functions. Long-term changes of the conditions of habitats, determined by human economic activities, influence the state of grassland plants. Rural Development Programme for Lithuania 2007–2013 sets measure to preserve biological diversity of grassland. The purpose of it is to reduce negative anthropogenic effect on grassland plant communities using the EU funds. Having researched the differences of grassland plant diversity and economic value, influenced by different intensity economic activities, the main objective of this paper is to evaluate the efficiency of EU regulated, agri-environmental measures based, grassland management methods in small farming sector of Lithuania. The research, involving the assessment of the number of plant species, diversity of plant families, distribution of relative plant abundance, and dominance of plant species in plant communities in grassland managed traditionally and according to the requirements of agri-environmental farming, showed that both types of grassland had similar plant communities. Such conclusion was drawn from the analysis of Jaccard and Sörensen similarity coefficients. The difference of plant adaptation to soil dampness, acidity, and nutrition was not statistically significant in grasslands of both types. Most of the plants in grassland researched were mesophytes; soil acidity was not a determining factor to... [to full text] / Pievos yra svarbus agrarinio kraštovaizdžio komponentas, atliekantis įvairias ekologines, ekonomines ir socialines funkcijas. Ilgalaikiai augaviečių sąlygų pokyčiai, kuriuos lemia žmogaus ūkinė veikla, įtakoja pievų augalų būklę. Lietuvos kaimo plėtros 2007–2013 m. programoje numatyta priemonė pievų biologinės įvairovės išsaugojimui, kurios tikslas panaudojant ES lėšas mažinti neigiamą antropogeninį poveikį pievų augalų bendrijoms. Ištyrus pievų augalijos įvairovės ir ūkinės vertės skirtumus, sąlygotus skirtingos ūkinės veiklos intensyvumo, šio darbo tikslas įvertinti reglamentuotų, ES agrarinės aplinkosaugos priemonėmis paremtų, pievų tvarkymo metodų efektyvumą smulkiuose Lietuvos ūkiuose. Atliktas tyrimas parodė, kad įvertinus augalų rūšių skaičių, augalų šeimų įvairovę, augalų rūšių santykinio gausumo pasiskirstymą, dominuojančias augalų rūšis tradiciniais ir agrarinės aplinkosaugos reikalavimus atitinkančiais ūkininkavimo metodais tvarkomose pievose, nustatyta, kad jose augo panašios augalų bendrijos. Tai parodė ir Žakaro bei Sörensen bendrumo koeficientų reikšmės. Abiejų tipų pievose rastų augalų rūšių prisitaikymo prie dirvožemio drėgmės, rūgštingumo, turtingumo maisto medžiagomis rodiklių reikšmės statistiškai reikšmingai nesiskyrė. Pievų augalų bendrijose vyravo mezofitai, daugumai augalų rūšių dirvožemio rūgštingumas buvo neįtakojantis veiksnys, pievoms būdingi mezooligotrofiniai ir mezotrofiniai žolynai. Tyrimas parodė, kad biologinės įvairovės apsaugai palankus... [toliau žr. visą tekstą]

Pievos yra svarbus agrarinio kraštovaizdžio komponentas, atliekantis įvairias ekologines, ekonomines ir socialines funkcijas. Ilgalaikiai augaviečių sąlygų pokyčiai, kuriuos lemia žmogaus ūkinė veikla, įtakoja pievų augalų būklę. Lietuvos kaimo plėtros 2007–2013 m. programoje numatyta priemonė pievų biologinės įvairovės išsaugojimui, kurios tikslas panaudojant ES lėšas mažinti neigiamą antropogeninį poveikį pievų augalų bendrijoms. Ištyrus pievų augalijos įvairovės ir ūkinės vertės skirtumus, sąlygotus skirtingos ūkinės veiklos intensyvumo, šio darbo tikslas įvertinti reglamentuotų, ES agrarinės aplinkosaugos priemonėmis paremtų, pievų tvarkymo metodų efektyvumą smulkiuose Lietuvos ūkiuose. Atliktas tyrimas parodė, kad įvertinus augalų rūšių skaičių, augalų šeimų įvairovę, augalų rūšių santykinio gausumo pasiskirstymą, dominuojančias augalų rūšis tradiciniais ir agrarinės aplinkosaugos reikalavimus atitinkančiais ūkininkavimo metodais tvarkomose pievose, nustatyta, kad jose augo panašios augalų bendrijos. Tai parodė ir Žakaro bei Sörensen bendrumo koeficientų reikšmės. Abiejų tipų pievose rastų augalų rūšių prisitaikymo prie dirvožemio drėgmės, rūgštingumo, turtingumo maisto medžiagomis rodiklių reikšmės statistiškai reikšmingai nesiskyrė. Pievų augalų bendrijose vyravo mezofitai, daugumai augalų rūšių dirvožemio rūgštingumas buvo neįtakojantis veiksnys, pievoms būdingi mezooligotrofiniai ir mezotrofiniai žolynai. Tyrimas parodė, kad biologinės įvairovės apsaugai palankus... [toliau žr. visą tekstą] / Grassland is an important component of agrarian landscape, performing wide range of ecological, economic and social functions. Long-term changes of the conditions of habitats, determined by human economic activities, influence the state of grassland plants. Rural Development Programme for Lithuania 2007–2013 sets measure to preserve biological diversity of grassland. The purpose of it is to reduce negative anthropogenic effect on grassland plant communities using the EU funds. Having researched the differences of grassland plant diversity and economic value, influenced by different intensity economic activities, the main objective of this paper is to evaluate the efficiency of EU regulated, agri-environmental measures based, grassland management methods in small farming sector of Lithuania. The research, involving the assessment of the number of plant species, diversity of plant families, distribution of relative plant abundance, and dominance of plant species in plant communities in grassland managed traditionally and according to the requirements of agri-environmental farming, showed that both types of grassland had similar plant communities. Such conclusion was drawn from the analysis of Jaccard and Sörensen similarity coefficients. The difference of plant adaptation to soil dampness, acidity, and nutrition was not statistically significant in grasslands of both types. Most of the plants in grassland researched were mesophytes; soil acidity was not a determining factor to... [to full text]

Les algues del gènere Cystoseira són els principals organismes formadors d'estructura en fons rocosos ben il·luminats del Mar Mediterrani. Formen unes comunitats molt estructurades que s'assemblen ecològicament als boscos terrestres i que són sensibles als impactes antròpics. Aquesta tesi s'ha centrat en l'estudi de les espècies i comunitats dominades per Cystoseira que es troben en ambients calmats, és a dir, en petites cales i/o badies. S'han abordat diversos aspectes com són la distribució, composició, estructura i biogeografia d'aquestes comunitats, així com els efectes de la contaminació sobre les mateixes. Per una banda, s'ha documentat l'estat actual de les comunitats dominades per C. crinita a nombrosos llocs al llarg de tot el Mediterrani, aportant informació sobre la seva composició, estructura, variació biogeogràfica i dinàmica de la comunitat a llarg termini. S'ha documentat la desaparició de diverses espècies de Cystoseira en zones afectades per impactes antròpics diversos i s'ha proporcionat la primera evidència experimental de la desaparició d'espècies de Cystoseira a causa de la contaminació. / Macroalgae of the genus Cystoseira are the main engineering species in shallow rocky bottoms in the Mediterranean Sea. They dominate diverse and structured assemblages which are ecologically similar to terrestrial forests and show high sensitivity to human impacts. This thesis has focused on the study of the species and assemblages dominated by Cystoseira which appear in sheltered environments, such as bays and small coves. The study of the distribution, composition, structure, biogeography, effects of pollution and recovery potential of these assemblages are the main subjects of the thesis. By one hand, the current state of C. crinita-dominated assemblages has been assessed for many localities through the Mediterranean. Information on the composition, structure, biogeography and long-term dynamics of these assemblages has been provided. The disappearance of different Cystoseira species in impacted areas has been documented and the first experimental evidence of pollution negative effects on Cystoseira populations has been provided.