Vegetation in the San Cristobal Valley of Barry M. Goldwater Range-East was mapped using a combination of field surveys and aerial imagery interpretation to contribute to ongoing inventory of natural resources for the BMGR-East as well as assist in resource management decisions. Eighteen vegetation associations were identified and mapped through collection of 186 samples to characterize vegetation associations. The most common vegetation association was Larrea tridentata monotype, covering 29% of the area mapped. Larrea tridentata is a widely spread shrub throughout the Sonoran, Chihuahuan and Mojave deserts; therefore understanding germination and seedling survival patterns is crucial. Ambrosia dumosa and A. deltoidea exhibit nurse plant-protégé interactions with L. tridentata. Seed density of L. tridentata was studied under Ambrosia species to determine factors controlling germination and seedling density. As expected seed density was greater under Ambrosia canopy than areas with no canopy. Ambrosia species and canopy type did not affect seed density.

This study examined the effects of seedbed and seedling environment on establishment of early and late seral dominant alpine species. Species studied included late seral dominant forbs (Geum rossii, Artemisia scopulorum, and Polemonium viscosum), early seral dominant forbs (Potentilla diversifolia and Sibbaldia procumbens), a late seral dominant grass (Festuca idahoensis), and early seral dominant grasses (Calamagrostis purpurascens and Deschampsia cespitosa). Germination responses of each species to wet vs. dry cold stratification and light vs. dark conditions were investigated. No statistical differences were observed in the seed germination of early and late seral dominant forbs or early and late seral dominant grasses, but significant differences were observed in the responses of grasses and forbs. Seed germination of forbs was greater under light than dark conditions and following wet cold storage. Effects of fertilization on growth responses and nutrient uptake of G. rossii and D. cespitosawere evaluated in a factorial greenhouse experiment in which seedlings of each species were grown at four levels of nitrogen (N) and phosphorous (P). The late seral dominant forb responded more like a species from a low-nutrient environment exhibiting lower relative growth rates, higher root:shoot ratios, and a smaller response to N than the early seral dominant. A field experiment on the Beartooth Plateau, Montana, examined the soil environment and seedling emergence, growth, and survival of seeded early and late seral dominants on loamy sand soils of a severe disturbance and on peat soils of an undisturbed area during two growing seasons. Effects of fertilizer and mulch were examined on the severely disturbed area. Differences between uncleared turf and turf cleared of vegetation (gap disturbance) were evaluated on the undisturbed area. The gap disturbance had higher levels of N and P and warmer soil than the severe disturbance or vegetated undisturbed area. Soil water potentials were never low enough to result in plant stress. Seedling growth was slow - .005 g to .04 g dry weight the first growing season and .02 g to .20 g the second growing season. Growth was greatest on the gap disturbance and on fertilized plots of the severely disturbed area. Early seral dominants had the largest seedlings and the smallest R/R+S ratios. Mortality was low - odds of .50 were rarely exceeded even after two years. Survival was higher on warm, nutrient rich soils of the gap disturbance. Mulch increased emergence and survival on the severe disturbance. Fertilization increased mortality, probably because an initial pulse of N was followed by a rapid decline. Higher mortality occurred in 1986 than 1985 as 1986 had a shorter growing season and cooler air and soil temperatures early in the growing season.

The establishment of alfalfa is expensive and good initial stands permit the farmer to secure high yields and spread establishment costs over several years, Of the factors involved: seedbed preparation, fertilization, seed viability, method of planting, and water application are controlled by the farmer, On the other hand, beneficial and detrimental microflora are not so easily controlled because practices aimed at controlling the detrimental microflora may also destroy the beneficial.

A trade-off between seed size and seed number is central in seed ecology, and has been suggested to be related to a trade-off between competition and colonization, as well as to a trade-off between stress tolerance and fecundity. Large seeds endure hazards during establishment, such as shading, drought, litter coverage and competition from other plants, better than do small seeds, due to a larger amount of stored resources in the seed. Small seeds, however, are numerous and small-seeded species are therefore more fecund. Moreover, a pattern with small-seeded species being associated with open habitats and large-seeded species being associated with closed habitats has been reported in the literature. In this thesis I assess effects of seed size on recruitment, and how relationships between seed size and recruitment may relate to habitat conditions. Seed sowing experiments were performed in the field to assess inter- and intra-specific relationships between seed size and recruitment in open and closed habitats (Paper I and II). Seed removal experiments were performed in the field to assess what effects seed predation may have on a relationship between seed size and recruitment (Paper III). A garden experiment was performed based on contests between larger-seeded and smaller-seeded species, in order to examine different models on co-existence of multiple seed size strategies. The results showed that there was a weak positive relationship between seed size and recruitment in the field, and that this relationship was only weakly and inconclusively related to habitat (Paper I and II). Seed removal was negatively related to seed size in closed habitats and unrelated to seed size in open habitats (Paper III). This indicates that any positive relationship between seed size and recruitment may be an effect of higher seed removal in small-seeded species. However, when grown under controlled conditions in a garden experiment, there was a clear advantage of larger-seeded species over smaller-seeded species (Paper IV). This advantage was unaffected by seed density, indicating that there was no competitive advantage of the larger-seeded species. Instead, indirect evidence suggests that larger-seeded species exhibit higher tolerance to stress. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Accepted.</p><p> </p>

This study focuses on how established shrub seedlings (Salix myrsinifolia x phycilifolia and Vaccinium vitis-idaea) develop in historical milking grounds. Historical milking grounds are cultural remains from the intensive reindeer herding era when the Sami migrated with closely controlled herds. Although the places were never fenced, the high concentration of reindeer close to the tenting grounds created patches of grass and forb dominated vegetation in areas outherwise dominated by deciduous or ericoid shrubs. Despite about 100 years of abandonment the shrubs have not come back and the milking grounds are still clearly visible in the landscape. One theory why the former milking grounds are so stable is that shrubs cannot establish from seedlings due to unfavorable abiotic conditions, or due to competitive dominance of already established forbs and grasses. I tested this hypothesis by planting shrub seedlings in the milking grounds and in reference areas, with and without neighboring vegetation and investigated seedling survival and growth. The results show that shrub seedlings are able to both survive and develop in milking grounds suggesting that the seedling state is not the limiting factor in shrub encroachment in the milking grounds.

As características da regeneração natural no sub-bosque de comunidades florestais em processo de restauração expressam os principais indicadores de sucesso dos projetos de restauração ecológica, sendo que a ausência ou a baixa qualidade de regeneração natural são os principais gargalos para a perpetuação de projetos inseridos em paisagens muito fragmentadas. No entanto, condições adversas de micro-sítio de regeneração sob plantios de restauração podem restringir a colonização do sub-bosque por espécies nativas, comprometendo a sua perpetuação no tempo. O objetivo desse estudo foi avaliar se, e como, as condições físico-químicas do micro-sítio de regeneração, no sub-bosque de áreas em processo de restauração com diferentes idades, podem limitar o estabelecimento de espécies arbóreas nativas, restringindo assim, a restauração da dinâmica florestal. O estudo foi desenvolvido em três áreas em processo de restauração com diferentes idades (10, 22 e 55 anos), implantadas via reflorestamentos de alta diversidade. Foi realizada a caracterização físico-química do micro-sitio de regeneração das áreas de estudo, avaliando-se o grau de compactação, porosidade, umidade, conteúdo de matéria orgânica e nutrientes e granulometria do solo, bem como a massa seca de serapilheira, e a cobertura do dossel. Em cada área de estudo, foram alocados 10 blocos experimentais, cada um constituído por 4 parcelas de 1 m x 1 m, onde foram semeadas nove espécies arbóreas nativas regionais. Nessas parcelas foram estabelecidos três tratamentos e um controle: A) semeadura na condição natural da área, sem qualquer alteração das características do micro-sítio de estabelecimento (serapilheira autóctone), B) semeadura sobre a serapilheira e o solo transplantados de floresta nativa (serapilheira alóctone), C) semeadura sobre bagaço de cana triturado e compostado e D) controle (sem semeadura). A coleta dos dados de emergência e mortalidade de plântulas foi feita por um período de 6 meses. Ocorreu um gradiente de aumento da cobertura do dossel, da porosidade, da umidade, do conteúdo de argila e matéria orgânica e uma diminuição da compactação do solo das áreas restauradas mais novas para as mais velhas. A emergência de plântulas não diferiu entre as áreas de estudo, porém, a sobrevivência de plântulas foi significativamente menor na restauração mais antiga, de 55 anos. Constatou-se uma correlação positiva entre a mortalidade de plântulas com o aumento da cobertura do dossel e com a quantidade de matéria orgânica no solo. A emergência e a sobrevivência de plântulas foram estatisticamente maiores no tratamento onde as sementes foram aplicadas sobre serapilheira autóctone. Assim, conclui-se que apesar das condições de micro-sítio de regeneração de florestas em restauração tornarem-se, com o tempo, mais semelhantes à de florestas naturais, tornam-se cada vez mais restritivas ao estabelecimento de plântulas. Além disso, o estabelecimento de plântulas é favorecido nas condições locais de substrato de florestas em processo de restauração florestal, sem limitação evidente para que a sucessão secundária avance. Conseqüentemente, a limitação de dispersão deve ter influência maior nessas condições para o avanço inicial da restauração do que a limitação de micro-sítios favoráveis de estabelecimento. / The characteristics of the natural regeneration of restoration plantings understory express the main indicators of success of ecological restoration projects, in which the absence of regeneration indicates a bottleneck for the perpetuation of forest communities inserted into highly fragmented landscapes. Nevertheless, adverse conditions of the micro-site of regeneration in restoration plantings may hamper the colonization of the understory by native species, which in turn collapse its perpetuation along the time. We sought to evaluate if, or how, the physical-chemical conditions of the micro-site of regeneration of restoration plantings with different ages can limit native tree species establishment and therefore, the dynamic of forest restoration. The study was developed in three areas under restoration with different ages (10, 22 and 55 years). The physical-chemical characterization of the micro-site of regeneration of the study areas was carried out by evaluating the soil compression level, porosity, humidity, organic matter and nutrients content and granulometry, as well as litter dry mass and canopy cover. In each area, we set 10 experimental blocks, each one consisting of four 1 m x 1 m plots, in which nine tree species were sown. In each plot we established three treatments: A) direct seeding in the natural condition of the area, without any alteration in the characteristics of the micro-site (indigenous leaf litter), B) direct seeding on the leaf litter and soil transplanted from a native forest (allochthonous leaf litter), C) direct seeding on grounded and composted sugarcane bagasse and D) control (no seeding). Seedling emergence and mortality were observed through six months. An increase on the canopy cover and soil porosity, humidity, clay and organic matter content were observed in the oldest areas, as well as a decrease in soil compression. Seedling emergence did not differ among the studied areas; however, seedling survival was significantly lower in the oldest reforestation, with 55 years. A positive correlation was observed between seedling mortality with the increase of canopy cover and soil organic matter content. Seedling emergence and survival were statistically higher in the treatment A (indigenous leaf litter). Thus, although the micro-site conditions for seedling establishment become even more similar to reference ecosystems as restoration planting evolve, it also becomes more restrictive. In addition, seedling establishment was favored in the conditions of local substrate of restoration plantings, without evidence of limitation for the progress of secondary succession. Consequently, dispersal limitation may play a higher influence in this condition for the advance of restoration process.

The New Zealand alpine zone has many fleshy-fruited plant species, but now has a relatively depauperate animal fauna. The key question is, therefore, are native alpine plants still being dispersed, if so where to and by what? I first measured fruit removal rates among nine common species using animal-exclusion cages to compare natural fruit removal by all animals, and by lizards only. Over two years, mean percent of fruit removed by early winter ranged from 25–60% among species. Speed of fruit removal also varied depending on species. Secondly, I quantified which animals disperse (or predate) seeds of those fruits, into which habitats they deposit the seeds, and the relative importance of each animal species for dispersal, in two ways. A 2-year study using fixed-area transects to monitor faecal deposition showed that introduced mammals (especially possums, rabbits, hares, sheep, pigs and hedgehogs) were abundant and widespread through alpine habitat. Of the 25,537 faeces collected, a sub-sample of 2,338 was dissected. Most mammals dispersed most (> 90%) seeds intact. However, possums (numerically the important disperser) moved most seeds into mountain beech (Nothofagus solandri) forest, while rabbits, hares, and sheep dispersed seeds mainly into open grassland dominated by thick swards of exotic grasses (e.g. Agrostis capillaris and Anthoxanthum odoratum); all are less suitable microsites. Kea (Nestor notabilis), the largest and most mobile of only three remaining native alpine bird species, are potentially useful as a long-distance seed disperser, even though parrots are typically seed predators. I found that kea are numerically more important than all other birds combined, damage very few seeds, and are probably responsible for most dispersal of seeds between mountain ranges. Finally, I investigated the effects of seed deposition microsite (shady/high-light), pulp-removal (whole/cleaned), competition (soil dug/not-dug) and predation (caged/ not) on germination, growth and survival of eight subalpine plant species. There were strong positive effects of shady microsites for seed germination and seedling survival to 3.5 years for six of the eight species. Effects of other treatments were less important and varied among species and stages. Hence, both native birds and introduced mammals are dispersing alpine seeds, but the mammals often deposit seeds in habitats unsuitable for establishment. Any evaluation of the dispersal effectiveness of frugivores must consider their contribution towards the long-term success for plant recruitment through dispersal quantity and quality.

As características da regeneração natural no sub-bosque de comunidades florestais em processo de restauração expressam os principais indicadores de sucesso dos projetos de restauração ecológica, sendo que a ausência ou a baixa qualidade de regeneração natural são os principais gargalos para a perpetuação de projetos inseridos em paisagens muito fragmentadas. No entanto, condições adversas de micro-sítio de regeneração sob plantios de restauração podem restringir a colonização do sub-bosque por espécies nativas, comprometendo a sua perpetuação no tempo. O objetivo desse estudo foi avaliar se, e como, as condições físico-químicas do micro-sítio de regeneração, no sub-bosque de áreas em processo de restauração com diferentes idades, podem limitar o estabelecimento de espécies arbóreas nativas, restringindo assim, a restauração da dinâmica florestal. O estudo foi desenvolvido em três áreas em processo de restauração com diferentes idades (10, 22 e 55 anos), implantadas via reflorestamentos de alta diversidade. Foi realizada a caracterização físico-química do micro-sitio de regeneração das áreas de estudo, avaliando-se o grau de compactação, porosidade, umidade, conteúdo de matéria orgânica e nutrientes e granulometria do solo, bem como a massa seca de serapilheira, e a cobertura do dossel. Em cada área de estudo, foram alocados 10 blocos experimentais, cada um constituído por 4 parcelas de 1 m x 1 m, onde foram semeadas nove espécies arbóreas nativas regionais. Nessas parcelas foram estabelecidos três tratamentos e um controle: A) semeadura na condição natural da área, sem qualquer alteração das características do micro-sítio de estabelecimento (serapilheira autóctone), B) semeadura sobre a serapilheira e o solo transplantados de floresta nativa (serapilheira alóctone), C) semeadura sobre bagaço de cana triturado e compostado e D) controle (sem semeadura). A coleta dos dados de emergência e mortalidade de plântulas foi feita por um período de 6 meses. Ocorreu um gradiente de aumento da cobertura do dossel, da porosidade, da umidade, do conteúdo de argila e matéria orgânica e uma diminuição da compactação do solo das áreas restauradas mais novas para as mais velhas. A emergência de plântulas não diferiu entre as áreas de estudo, porém, a sobrevivência de plântulas foi significativamente menor na restauração mais antiga, de 55 anos. Constatou-se uma correlação positiva entre a mortalidade de plântulas com o aumento da cobertura do dossel e com a quantidade de matéria orgânica no solo. A emergência e a sobrevivência de plântulas foram estatisticamente maiores no tratamento onde as sementes foram aplicadas sobre serapilheira autóctone. Assim, conclui-se que apesar das condições de micro-sítio de regeneração de florestas em restauração tornarem-se, com o tempo, mais semelhantes à de florestas naturais, tornam-se cada vez mais restritivas ao estabelecimento de plântulas. Além disso, o estabelecimento de plântulas é favorecido nas condições locais de substrato de florestas em processo de restauração florestal, sem limitação evidente para que a sucessão secundária avance. Conseqüentemente, a limitação de dispersão deve ter influência maior nessas condições para o avanço inicial da restauração do que a limitação de micro-sítios favoráveis de estabelecimento. / The characteristics of the natural regeneration of restoration plantings understory express the main indicators of success of ecological restoration projects, in which the absence of regeneration indicates a bottleneck for the perpetuation of forest communities inserted into highly fragmented landscapes. Nevertheless, adverse conditions of the micro-site of regeneration in restoration plantings may hamper the colonization of the understory by native species, which in turn collapse its perpetuation along the time. We sought to evaluate if, or how, the physical-chemical conditions of the micro-site of regeneration of restoration plantings with different ages can limit native tree species establishment and therefore, the dynamic of forest restoration. The study was developed in three areas under restoration with different ages (10, 22 and 55 years). The physical-chemical characterization of the micro-site of regeneration of the study areas was carried out by evaluating the soil compression level, porosity, humidity, organic matter and nutrients content and granulometry, as well as litter dry mass and canopy cover. In each area, we set 10 experimental blocks, each one consisting of four 1 m x 1 m plots, in which nine tree species were sown. In each plot we established three treatments: A) direct seeding in the natural condition of the area, without any alteration in the characteristics of the micro-site (indigenous leaf litter), B) direct seeding on the leaf litter and soil transplanted from a native forest (allochthonous leaf litter), C) direct seeding on grounded and composted sugarcane bagasse and D) control (no seeding). Seedling emergence and mortality were observed through six months. An increase on the canopy cover and soil porosity, humidity, clay and organic matter content were observed in the oldest areas, as well as a decrease in soil compression. Seedling emergence did not differ among the studied areas; however, seedling survival was significantly lower in the oldest reforestation, with 55 years. A positive correlation was observed between seedling mortality with the increase of canopy cover and soil organic matter content. Seedling emergence and survival were statistically higher in the treatment A (indigenous leaf litter). Thus, although the micro-site conditions for seedling establishment become even more similar to reference ecosystems as restoration planting evolve, it also becomes more restrictive. In addition, seedling establishment was favored in the conditions of local substrate of restoration plantings, without evidence of limitation for the progress of secondary succession. Consequently, dispersal limitation may play a higher influence in this condition for the advance of restoration process.

Abstract Mutualism is often conditional and the associations vary from antagonism to mutualism along environmental conditions and genotypes of interacting species. I studied antagonism-mutualism continuum hypothesis of symbiosis experimentally using two different Epichloë/Neotyphodium endophytes and their host grasses, agricultural meadow fescues and natural fine fescue, as study systems. These systemic fungal endophytes live asymptomatically within aerial tissues of grasses, and are vertically transmitted to the next grass generation via seeds. Thus, asexual endophyte strains are dependent on the growth, survival and reproduction of their hosts. Epichloë/Neotyphodium endophytes are considered plant mutualists, because they improve the resistance of the host against various stresses, e.g. herbivores. In addition to experimental approach, I examined prevalence and genetic structure of Epichloë festucae in natural grass populations. Finally, current knowledge concerning grass endophytes was reviewed and the effects of variable environment and genetic background on the ecology and the evolution of grass-endophyte symbiosis were discussed. The endophyte improved the performance of the agronomic meadow fescues, but the beneficial effects were dependent on the grass cultivar and the growth environment. The endophyte-infected (E+) meadow fescues were more susceptible to the pathogenic snow molds and they suffered increased winter damage compared to the endophyte-free (E-) plants. Many natural Festuca rubra and F. ovina populations were either endophyte-free or had low infection frequency. The highest infection frequencies were found in subarctic areas where the infection incidence differed between habitats. Twenty out of the 25 E. festucae genotypes detected were carrying multiple alleles in microsatellite loci indicating multiple infections or vegetative hybridization of the fungus. A dominant genotype (63.5% of all isolates) occurred in all populations suggesting that this fungus is mainly asexual. E+ F. ovina seedlings performed worse than endophyte-free E- seedlings. In F. rubra, the river bank originated E+ seedlings allocated fewer, but longer and heavier tillers than the other seedlings indicating possible improved performance of the endophyte infected grasses in harsh river bank conditions. In short, I detected both positive and negative effects of endophyte infection on grasses varying along species, environment and genotypic background of study subjects. The results support the antagonism-mutualism continuum hypothesis.

MSc (Botany) / Department of Botany / See the attached abstract below