Ecological and environmental aspects relating to Cercocarpus montanus Raf. Communities were investigated. Twenty study sites were sampled and described. All factors were then analyzed utilizing statistical methods. Signigicantly correlated factors to C. montanus parameters (i.e., frequency, density, cover, height) were: positive correlation--percent clay, percent clay-silt, percent litter cover, and total soluble salts in soil; negative correlation--percent silt-sand, percent sand, soil pH; exposed surface rock, Amelanchier alnifolia cover, Gotierrezia sarothrae cover and altitude. Several individual factors were singled out as being of importance in C. montanus communities; howerver, it was shown that a combination of factors was most important in determining optimal growth conditions for C. montanus. Each site is exposed to different combinations of ecological conditions which are in a constant state of flux. The C. montanus communities studied were found in this condition. The actual successional patterns involved remain to be fully elucidated.

Diversity of ectotrophic mycorrhizal (EM) fungi on out-planted seedlings of two oak species (Quercus rubra and Q. prinus) was estimated at two sites in mature mixed forests in the southern Appalachian mountains. Late – stage fungi were well represented. Total richness was 73 types, with 42 types having a frequency of only one. Thelephoroid / tomentelloid, russuloid, and cortinarioid groups were the richest. Dominant fungi included a putative Tuber sp. and Craterellus sp., and Laccaria cf laccata. Diversity was lower at a high elevation chestnut oak dominated site compared to a lower mesic cove – hardwood forest site. There was little evidence for fungal specificity to red oak versus white oak seedlings. We also compared EM fungus distributions on root systems of oak seedlings from samples taken in mid-July and early-September. The majority of EM types occurred only in the mid- or late-summer samples respectively. Dramatic shifts in mycobiont dominance were observed in relation to sample date, including increases in Cortinarius spp. richness, decreases in Thelephoraceae richness, and the disappearance of Amanita spp. types in the late- compared to mid-summer samples. A multi-stage model of seasonal EM dynamics is proposed, with implications for the niche expansion of associated phytobionts. In this model, generalistic mycobionts are most frequent and occur throughout the season. Other more specialized fungi show seasonal specificity. Relationships between species and communities of EM fungi and environmental parameters such as ericoid shrub abundance and edaphic characteristics were also examined. High diversity of EM fungi limited resolution of community level relationships given our sample sizes. Intraspecific variation in EM fungi with regard to microsite characteristics was also undetectable. No association between ericoid shrub dominance (Kalmia latifolia and Rhododendron maximum) and EM fungi was observed. We present a listing of EM fungus types with associated ranges of edaphic parameters and ericoid shrub abundance. The family Sebacinaceae is a basal hymenomycete lineage that includes members of the genera Tremellodendron and Sebacina. We present evidence suggesting the putative mycorrhizal status of two species of Tremellodendron. Tremellodendron appears to form both endophytic associations with achlorophyllous orchids and ectomycorrhizae with species of Quercus, Pinus and Tilia cordata. / Ph. D.

Historical land use and changes in climate have altered fire behavior and severity in fire-prone ecosystems of western North America. A variety of fuels treatments are used to abate fire hazard, restore ecosystem processes, and increase forest resilience. Mechanical fuels treatments are increasingly used to alter forest structure and fuel continuity due to impediments to the use of prescribed fire. An increasingly common fuels treatment is mechanical mastication. Mastication does not remove fuels, but instead rearranges live and dead vertical woody fuels into a compacted layer on the forest floor. While mastication reduces potential fire intensity, these compacted fuels are flammable and capable of causing tree mortality and other negative ecological consequences when they burn in prescribed fires or wildfires. A current knowledge gap is quantitative information about the rate at which masticated fuels decompose and the rate at which vegetation reestablishes within sites previously masticated. Using 25 sites across northern California and southern Oregon, this thesis examines how masticated fuels change over time. Results from this study demonstrate that the majority of mass lost from masticated fuel beds occurred in the 1 and 10-hour woody fuel classes. Because surface fire behavior is driven by these fine fuels, these findings are valuable to the planning and retreatment of masticated fuels treatments and the corresponding fire suppression efforts in masticated sites. In combination with masticated wood surface fuels, shrubs and small trees play an important role in fire behavior, acting as ladder fuels that exacerbate surface fire behavior and threaten to ignite residual trees. A lack of understanding of how woody vegetation recovers following masticated fuel treatments gives rise to questions and challenges regarding treatment longevity. In this study, species with the ability to resprout tended to recover more quickly than obligate seeding species. Residual conifer saplings or trees that establish in masticated fuelbeds also recovered rapidly, reducing the efficacy of fuels treatments. Future implementation of masticated fuels treatments should consider both woody fuel decomposition and the corresponding recovery of shrubs and small trees to maximize treatment longevity. / Master of Science

7 pp. / Shrubs can greatly enhance the landscaping of your home year round. Different types of shrubs, their landscape usage, selection and cultural requirements are discussed here in detail.

3 pp. / Originally published: 2003 / True mistletoes are parasitic flowering plants with characteristic clumps of growth that are easily visible on the host plant. They reduce the growth of infected hosts, but it usually takes many years for true mistletoe infections to kill a mature tree or shrub. This article gives information about the disease cycle, the symptoms and prevention and control methods for true mistletoes.

Nos últimos anos, diversos estudos têm sido realizados em matas ciliares pelo Brasil devido, principalmente, ao crescente desmatamento que aí ocorre associado à percepção da importância dessas matas para o equilíbrio do ambiente. Apesar disso, pode-se considerar que ainda são poucos os estudos sobre composição florística das matas ciliares do bioma cerrado. O presente trabalho consiste no levantamento florístico de espécies arbustivas e arbóreas da mata de galeria do Capão Azul, situada em meio a campos rupestres, no Parque Estadual do Rio Preto, município de São Gonçalo do Rio Preto, MG, região central da Cadeia do Espinhaço. Os espécimes botânicos foram coletados entre agosto de 2005 a março de 2007, em diferentes épocas do ano. As espécies foram identificadas e descritas, além de serem fornecidos comentários de distribuição geográfica e habitat e de ter sido elaborada uma chave de identificação para as espécies que ocorrem na mata. Foram identificadas 91 espécies pertencentes a 71 gêneros, distribuídos em 38 famílias, sendo 1 pteridófita, 1 gimnosperma e 89 angiospermas. As famílias mais representativas em número de espécies foram: Melastomataceae (11), Myrtaceae (10), Rubiaceae (9) e Fabaceae (7). Comparações realizadas com outras matas mostraram que a maioria das espécies são generalistas quanto ao habitat e apresentam distribuição que vai além da região Sudeste. Além disso, muitas delas são provenientes das matas decíduas e semidecíduas. / In the last years several researches have been done in gallery forests in Brazil. The mainly reason for that, is the growing deforestation ocurred in this environment, associated to the perception of the importance of them. Although, we can say that there are still few researches in the biome \"cerrado\". The present work consists on the floristic survey of shrubs and trees of the Capão Azul gallery forest, Parque Estadual do Rio Preto, São Gonçalo do Rio Preto, MG, central region of the Espinhaço mountain range. The species were collected from August 2005 to March 2007 in differents seasons. This work provides an identification species key, comments on geographic distribution and habitat. Ninety one species have been identified, belonging to 71 genera and distributed in 38 families, one of them pteridophyta, one gimnosperm and 89 angiosperms. The families with the greatest number of species are Melastomataceae (11), Myrtaceae (10), Rubiaceae (9) and Fabaceae (7). Comparisons with others forests showed that most of the species are generalists for habitats and have geographic distribution over there South-east region. Besides, a great deal of them belongs to the deciduous and semideciduous forests.

A alelopatia, na qual uma espécie causa efeitos negativos sobre outra através da liberação de substâncias químicas, é um fenômeno que pode afetar comunidades vegetais. Em alguns casos, o estabelecimento de arbustos aromáticos em formações densas, com apenas poucas espécies ocorrendo em suas proximidades, é um padrão que tem sido relacionado aos efeitos fitotóxicos dos voláteis que os mesmos liberam. Em campos dos sul do Brasil, esse padrão de estabelecimento frequentemente ocorre para as espécies arbustivas aromáticas Heterothalamus psiadioides Less e Baccharis patens Baker, indicando a possibilidade de alelopatia. Dessa forma, o presente estudo teve como objetivo determinar se H. psiadioides e B. patens são fitotóxicas e se isso implica em efeitos negativos sobre a comunidade vegetal na qual os arbustos ocorrem. Em ensaios em laboratório, os efeitos dos voláteis liberados diretamente das folhas frescas e secas de H. psiadioides e B. patens foram testados sobre a germinação e o crescimento das plantas-alvo alface e cebola nas quatro estações do ano. Em um estudo em campo, foram avaliadas cobertura e biomassa vegetal, número de mudas, diversidade, riqueza, e variáveis de estrutura da vegetação no entorno de ambas as espécies arbustivas e onde não havia arbustos. Nos bioensaios, os voláteis de H. psiadioides e B. patens causaram inibição na porcentagem e velocidade de germinação e redução no tamanho da raiz e da parte aérea das plantas-alvo, sendo que folhas frescas apresentaram maior fitotoxidez. Esses parâmetros foram mais afetados por H. psiadioides que por B. patens em todas as estações, e os efeitos de ambas foram menores no verão. Em relação à investigação em campo, que objetivou avaliar os efeitos da espécie muito fitotóxica H. psiadioides sobre a comunidade vegetal, não foram observadas evidências de alelopatia. Houve maior riqueza e diversidade próximo a H. psiadioides, devido à menor cobertura de gramíneas dominantes. Variáveis de estrutura da vegetação e intensidade de luz explicaram os padrões observados de forma mais conclusiva que alelopatia. Esse estudo sugere que o potencial alelopático de plantas pode ser superestimado em bioensaios e que estudos em campo são necessários para demonstrar se efeitos alelopáticos são realmente relevantes em comunidades vegetais. Ainda, o trabalho ressalta a importância de conduzir estudos mais realistas em laboratório e de utilizar controles em estudos em campo. / Allelopathy, in which a species causes negative effects on another through the release of chemical substances, is a phenomenon that may affect plant communities. In some cases, the establishment of aromatic shrubs in dense stands, with few other species occurring in their surroundings, has been related to the phytotoxic effects of volatiles released by these shrubs. In South Brazilian grasslands, this pattern of establishment often occurs for the aromatic shrub species Heterothalamus psiadioides Less and Baccharis patens Baker, indicating the possibility of allelopathy. Thus, this study aimed to determine if H. psiadioides and B. patens are phytotoxic and if this implicates in negative effects on the plant community in which the shrubs occur. In laboratory assays, the effects of the volatiles released directly from fresh and dry leaves of H. psiadioides and B. patens on germination and growth of the target plants lettuce and onion were evaluated in four seasons. A field study was carried out, in which vegetation cover and biomass, number of seedlings, diversity, richness, and variables of vegetation structure were evaluated in the surroundings of both species and where there were not shrubs. In the bioassays, H. psiadioides and B. patens volatiles inhibited the germination rate and speed of germination and reduced the root and shoot length of the target plants, with fresh leaves showing higher phytotoxicity. These parameters were more strongly affected by H. psiadioides than by B. patens in all seasons, and effects of the both shrubs were lower in summer. In relation to the field investigation that aimed to quantify the effects of the highly phytotoxic H. psiadioides on the plant community, no evidences of allelopathy were found. Richness and diversity were higher near H. psiadioides, due to lower cover of dominant grasses. Variables of vegetation structure and light intensity explained vegetation patterns more conclusively than allelopathy. This study emphasizes that the allelopathic potential of plants can be overestimated in bioassays, and that field studies are necessary to elucidate if allelopathic effects are in fact significant in plant communities. Still, the relevance of conducting more realistic laboratory studies and of using controls in field studies is highlighted.

Digestion rates have been measured for brown trout (Salmo trutta Linn.) during summer, fall, winter and spring seasons on the Blacksmith Fork River, Utah. Exponential rates of digestion varied from a gradual rate of -0.2372 to an accelerated rate of -0.6808. Factors found to affect digestion rate most were water temperature and the amount of food in the stomach. The affect of temperature was not clearly isolated. However, the amount of food in the stomach, at the beginning of the digestion study, appeared to have the most pronounced effect. Four of the five digestion rate measurements, with high coefficients 'of determination, were highly correlated to changes in the amount of food in the stomach. A stomach capacity study was also conducted during the winter season. A comparison of the results of the present study with those of an earlier study conducted during the summer season exhibited two nearly parallel non-linear regression lines. The differences in stomach capacity ranged from only 0.02 cc at 170 mm fork length to 0.93 cc at 340 mm fork length. Throughout the 170 to 340 mm size range, stomach capacities were smaller in the present study than those reported in the earlier study. Although some differences in method of determining stomach capacity did occur, these differences should have led to larger stomach capacities in this study. Since season of collection was different, it is suspected that was largely responsible for these differences. Therefore, the results of the stomach capacity study indicate that stomach capacities can be expected to change between summer and winter seasons. However, these changes may not be significant.

The vegetation of the Sydney Basin, Australia, is highly flammable and subject to a wide range of fire regimes. Sclerophyllous shrubs and sedges are common and in some vegetation types up to 70 % of fuel consumed during a fire can be live. Research into fire behaviour and fuel dynamics has been minimal. To address this issue this thesis investigated the principal factor affecting the ease of ignition and rate of combustion of individual fuel particles and fuel beds in bushfires: dead fine fuel moisture (FFM). Two common Sydney Basin vegetation types, eucalypt woodland and heathland, each with a history of problematic fire management, were measured in the field for diurnal fluctuations in FFM following rain, under conditions similar to when prescribed burns are conducted. The FFM components of current operational fire behaviour models were found to be inadequate for predictions of FFM and fire behaviour under these conditions. The equilibrium moisture content (EMC) of five fuel types from the field site was investigated in a laboratory study. An existing function describing EMC as a function of temperature and relative humidity was evaluated and found to be very accurate for these fuels. Two FFM predictive models incorporating this function were evaluated on the field data and the laboratory results were shown to be applicable to the estimation of FFM in the field. One model gave very accurate predictions of FFM below fibre saturation point, but its accuracy was reduced when screen level conditions were used instead of those measured at fuel level. A recent process-based model that accounts for rainfall showed promise for predicting when fuel is < 25 % FFM. Systematic problems with the radiation budget of this model reduced the accuracy of predictions and further refinement is required. Live fine fuel moisture content (LFMC) of common heathland shrubs and sedge was investigated over two years and found to be both seasonal and influenced by phenology. LFMC minima occurred in late winter and spring (August to October), and maxima were in summer (December to February) when new growth was recorded. The dominant near-surface fuel in mature heath was sedge. It was found to have little seasonal variation in its??? percentage dead but the percentage dead maxima occured at the same time as the LFMC minima of shrubs and sedge in both years. Simple instantaneous models for duff moisture content in woodland and heathland and LFMC and the percentage dead sedge in heathland were developed. The information gained by this study will form the basis for future development of fuel moisture models for prescribed burning guidelines and fire spread models specific to the vegetation communities of the Sydney Basin.

This study considered the influence of exotic shrubs on birds in urban patches of Yellow Box- Blakely's Red Gum (E. melliodora-E. blakelyi) woodlands in the Australian Capital Territory, Canberra. The aim of this research was to identify native and exotic birds that have their abundance influenced by exotic shrubs. The purpose of this work was to provide more information to managers of this woodland about the potential impacts of weed control on birds living in woodland reserves adjacent to suburban areas. Birds were sampled between 1996 and 1998 using the twenty minute area-search method to derive estimates of bird abundance. Around 680 twenty minute area-searches were completed, with 665 of these undertaken at 12 two hectare plots with varying levels of exotic shrub cover over a period of ten months. The abundance of birds for each of the ten months sampled were compared by pooling sites into four classes of exotic shrub cover. Classes of exotic shrub cover were nil, light, moderate and dense. Seasonal inferences were drawn from non-parametric analysis of variance. Non-parametric measures of association were used to test for correlation between the mean abundance of bird species at different woodland sites and percentage foliage estimates of exotic shrub cover. Percentage foliage estimates of native shrub cover were included in tests for correlation between bird abundance and exotic shrub cover by applying partial measures of association. To support statistical information, observations of birds in exotic shrub cover were also recorded. In one woodland site birds were sampled before and after the removal of exotic shrub cover. No statistical tests were applied to these samples because of a lack of replication; however, descriptive graphs of the abundance of selected birds following weed control are presented. To investigate the effect that exotic shrub invasion may have on the composition of bird assemblages in woodland cluster analysis and ordination of the 12 sites using the mean abundance of the 75 species recorded between July 1997 and June 1998 were also undertaken. The presence of exotic shrub cover in E. melliodora-E. blakelyi woodland in Canberra was found to have differential effects on bird abundance. Wrens, finches, thornbills, whistlers and pigeons were more abundant in woodland sites where exotic shrubs were present when compared to sites with no or little exotic shrub cover. Fruit-eating birds, such as Silvereyes (Zosterops lateralis), Pied Currawong (Strepera graculina) and Crimson Rosella (Platycercus elegans), were more abundant in woodland with exotic shrubs in winter and autumn when these shrubs provided food in the form of berries. The abundance of fruit-eating birds, and wrens and finches was reduced in a single woodland site following the removal of most of the exotic shrub cover. The Common Blackbird (Turdus merula) was the only exotic bird which showed a strong association with exotic shrubs in woodland, while the Laughing Kookaburra (Dacelo novaeguineae) was negatively correlated with exotic shrub cover, possibly because prey is harder to detect and capture in woodland with a shrubby understorey. Cluster analysis and ordination of the 12 woodland sites did not group sites into the four experimental classes used to undertake analysis of variance. Multivariate analysis, however, did reveal that seasonal peaks in the abundance of fruit eating birds affected the composition of bird assemblages by increasing the mean abundance of these birds in densely invaded sites. Similarly, structural differences in the understorey resulted in some birds being more abundant in woodland sites invaded by exotic shrubs when compared to sites lacking a shrubby understorey. The distance between some sites confirmed this stark difference in bird life when plotted in three dimensions. The results of this study suggest that exotic shrubs add food and structural complexity to woodland habitat. Benefits of structural complexity for small native birds in woodland include nest sites and protection from predators. These benefits may operate at certain thresholds of invasion, as the woodland site with the densest level of exotic shrub invasion showed a slight decrease in the number of wrens and finches. Adverse impacts from exotic shrub invasion may include reduced open ground in which to forage and loss of floristic diversity in the understorey. In effect, exotic shrubs add and remove resources in woodland habitat, benefiting some bird species and limiting others. These findings suggest that the removal of exotic shrub cover in woodland located in urban landscapes simplifies the structural complexity of the understorey, reducing the quality of habitat for some birds. Thus, adverse impacts on biodiversity arising from the invasion of exotic shrubs in woodland need to be considered against the important role that a diverse bird population has in maintaining ecosystem function.