Investigations of three low-water requiring landscape species produced the following results: (1) Although Calliandra californica flowered under photoperiods from 12 to 16 hours, plants produced more elongation under 16 hour days. Plants grew taller and developed greener foliage under irradiances of 600 μmol·m⁻²·s⁻¹. Branching was not stimulated by foliar sprays of BA, PBA, or BA + GA₄₊₇. (2) Caesalpinia pulcherrima increased biomass under 16 hour days, but were stunted and chlorotic under irradiances of 1950 μmol·m⁻²·s⁻¹. Internodal lengths were restricted with drenches of 3.75 mg · pot-1 uniconazole, and plants sprayed with 500 mg·liter⁻¹ PBA developed more axillary branching without negative elongating effects. (3) Justicia specigera gained more height under 12 hour days, and produced greener foliage, more elongation, and faster flowering under irradiances of 600 μmol·m⁻²·s⁻¹. Plants showed restricted internodal elongation and fewer flowers when drenched with 5.0 mg·pot⁻¹ uniconazole, and developed more axillary branching with no detrimental elongation effects when sprayed with 100 mg·liter⁻¹ BA + GA₄₊₇.

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.

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.

Global climate change is already contributing to the extirpation of numerous species worldwide, and sensitive species will continue to face challenges associated with rising temperatures throughout this century and beyond. It is especially important to evaluate the thermal ecology of endangered ectotherm species now so that mitigation measures can be taken as early as possible. A recent study of the thermal ecology of the federally endangered Blunt-Nosed Leopard Lizard (Gambelia sila) suggested that they face major activity restrictions due to thermal constraints in their desert habitat, but that large shade-providing shrubs act as thermal buffers to allow them to maintain surface activity without overheating. We replicated this study but added a population of G. sila with no access to large shrubs to facilitate comparison of the thermal ecology of G. sila in shrubless and shrubbed populations. We found that G. sila without access to shrubs spent more time sheltering inside rodent burrows than lizards with access to shrubs, especially during the hot summer months. Lizards from a shrubbed population had higher midday body temperatures and therefore poorer thermoregulatory accuracy than G. sila from a shrubless population, suggesting that greater surface activity may represent a thermoregulatory tradeoff for G. sila. Lizards at both sites are currently constrained from using open, sunny microhabitats for much of the day during their short active seasons, and our projections suggest that climate change will exacerbate these restrictions and force G. sila to use rodent burrows for shelter even more than they do now, especially at sites without access to shrubs. The continued management of shrubs and of burrowing rodents at G. sila sites is therefore essential to the survival of this endangered species.

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Despite the numerous environmental benefits of conservation buffers and incentives offered by cost-share programs, adoption remains low. Typical buffer designs often take arable land out of production. Multifunctional conservation buffers (MCBs) offer an alternative that supports rather than excludes production. By incorporating non-timber forest products (NTFPs), edible or ornamental crops can be harvested for profit or home use, while retaining key environmental services. Beyond low adoption rates, little is known about the long-term retention of conservation buffers due in part to limited program evaluation funding. However, implementation of evaluation recommendations is imperative for buffer retention. With this in mind, we administered a mail survey to conservation buffer adopters throughout Virginia. The first objective was to evaluate post-adoption experiences with conservation buffers. We identified four landowner clusters with distinct differences in buffer perceptions and intentions to retain. Insights can help conservation agencies enhance programming to reduce negative buffer experiences and increase long-term retention. The second objective was to determine interest in and preferences for MCBs. We found respondents were somewhat to very interested in MCBs, and increases in this interest were influenced most by the buffer's potential to decrease soil loss. Respondents who found MCBs more appealing than traditional designs had supportive peers and higher expectations of MCB performance. Lastly, respondents preferred MCBs designed with nut or fruit producing trees that grow naturally. Findings can help inform future outreach and programming aimed at merging conservation and production in buffer zones. / Master of Science

This study addresses the nature of physiological and phenological evolutionary strategies of root growth dynamics and energy allocation followed by Atriplex confertifolia, Ceratoides lanata, and Artemisia tridentata growing in their natural cool desert environment. Root observation chambers with inclined Plexiglass windows were installed in monospecific desert communities of Atriplex confertifolia, Ceratoides lanata and Artemisia tridentata. Soil temperature and water potential measurements taken immediately adjacent to the observation windows indicated a minimal disturbance was caused by the presence of these chambers. For the three species initiation of root growth was observed before initiation of shoot activity, furthermore, active root growth extended over much longer periods during the year than shoot growth. Initial growth was observed for the three species in the upper soil layers in the spring. Later in the season most of the growth activity was measured at progressively greater depths in the soil. Measurable root growth was observed for Atriplexin August when the soil water potentials were in the range of -70 bars for 1972, and at water potentials of -60 bars for all three species during 1973. Detectable growth for these three species was recorded as late as January in 1974. Except for the main extension roots, individual apical meristems were seldom active for more than 2 weeks. Atriplex confertifolia and Ceratoides lanata plots were labeled during the growth season with 14Co2 in polyethylene enclosures to study both the partitioning of photosynthates to plant parts and their total allocation of carbon at the community level. A definite seasonal pattern of partitioning of recent photoassimilates corresponding to phenological events emerged. In the spring, photoassimilates were principally directed to shoot growth, especially expanding new leaves and vegetative buds. In terms of relative energy allocated to plant parts per unit dry weight basis, it appears that Ceratoides lanata expends less energy for reproductive organs. For both species, carbon used for new stems and previous years shoot growth appears to constitute a significant sink for energy use and storage. Relative translocation of carbon to roots was minimal during the spring for both species. It increased with the progression of the season reaching a maximum in July for Atriplex and at the end of the season for Ceratoides. Energy allocation at the community level for these species showed that approximately 60 and 40 percent of the recently photoassimilated 14C for the Atriplex-dominated community in July and September, respectively, appeared localized in the new shoot growth, the remaining was distributed in nearly equal amounts between previous year's shoot growth and the root system. The scheme of energy allocation in Ceratoides showed similar patterns of carbon utilization in July and September; approximately 80 percent of the fixed carbon was al located in approximately equal amounts to roots and new shoot growth with the remainder to the previous year's shoot growth. In the Ceratoides-dominated community 65 percent and 36 percent of 14C photoassimilated in April and July, respectively, and still remaining in the plant by September, was localized in the underground structures. Similarly, in the Atriplex community, 35 percent and 29 percent of the 14C incorporated in April and July appeared in the root system. From the total 14C photoassimilated in July for both communities, approximately 60 percent and 50 percent was retained in the plants by September in the Atriplex- and Ceratoides-dominated communities, respectively.

ABSTRACT COMPARATIVE SEQUENCE ANALYSIS OF THE INTERNAL TRANSCRIBED SPACER 2 REGION OF TURKISH RED PINE (Pinus brutia TEN.) AND NATURAL ALEPPO PINE (Pinus halepensis MILL.) POPULATIONS FROM TURKEY Tozkar, &Ouml / zge M.S., Department of Biology Supervisor: Prof. Dr. Zeki Kaya April, 2007, 107 pages Turkish red pine (Pinus brutia) is wide-spread and an important forest tree species in Turkey, occurring mainly in southern, western and north-western Turkey and as small isolated populations in the Black Sea region. Aleppo pine (Pinus halepensis) has naturally found only in Adana and Mugla provinces as small population in mixture with Turkish red pine. Although Turkish red pine and Aleppo pine are morphologically different, Turkish red pine has been regarded as subspecies of Aleppo pine by some taxonomists due to occurrence of natural hybridization between these two species. However, the phylogenic relationship between these species needs to be explored further. In the present study, by sampling overlapped populations of both species from Mugla and Adana provinces (4 populations of Turkish red pine and 3 populations of Aleppo pine), internal transcribed spacer (ITS) region of ribosomal DNA were comparatively studied with sequence analysis. Although ITS1, 5.8s and ITS2 regions of ribosomal DNA were studied with ITS primers, only ITS2 region was successfully amplified with polymerase chain reaction (PCR). The complete data set for this region was analysed using MEGA3.1 and Arlequin softwares. Analysis of molecular variance (AMOVA) demonstrated the highest genetic differentiation between Turkish red pine and Aleppo pine in Mugla with 100 percentage of variation. AMOVA analysis also indicated the possibility of low-level migration of genes between Turkish red pine and Aleppo pine populations in Adana with 50.65 percent of molecular variance. Haplotype comparison revealed that two major haplotypes were represented Based on the results of ITS2 region sequence analysis, Turkish populations of Aleppo pine and Turkish red pine populations could not be fully differentiated. In Mugla province Turkish red pine and Aleppo pine revealed more differentiation due to reproductive isolation. But in Adana province, two species shared more common genetic background due to possible hybridization. Since ITS2 region of nuclear ribosomal DNA revealed a few variable and parsimony informative sites for both species, thus, only ITS2 region of ribosomal DNA does not appear to be sufficient for fully resolving genetic relationships between Turkish red pine and Aleppo pine populations. Further studies including ITS1 and 5.8s regions of ribosomal DNA and populations included from major Aleppo pine distribution areas will be useful to understand the evolutionary relationship between Aleppo pine and Turkish red pine populations in Turkey.

The short-term responses of Cassiope tetragona, a high arctic evergreen shrub, to variations in growing season climate were examined using experimental manipulations of temperature and growing season length at Alexandra Fiord, Ellesmere Island. Surface temperatures in the field were increased an average of 1-2 °C in two communities using open-top greenhouses. Growing season length was altered in a snowbed community by using manual snow manipulations to change the date of snowmelt. Growth and reproductive responses of Cassiope tetragona to these manipulations were observed over two field seasons following treatment establishment. Natural variations in vegetative and reproductive characteristics of Cassiope tetragona were also monitored in unmanipulated communities selected to represent a range of environmental conditions at the study site. Retrospective analysis of past Cassiope growth and reproduction was used to provide a record of variations in productivity spanning 25-35 years which could be related to climate records from Ellesmere Island. For the retrospective analysis, patterns of internode lengths were used to delimit sections of annual growth and chronologies of annual stem elongation, leaf number and flower number were then analyzed using methods similar to those applied to tree-ring studies. In general, the reproductive parameters of Cassiope tetragona were observed to be highly responsive to short-term variations in growing season climate, while vegetative production exhibited a much more conservative response. Flower production and rates of reproductive development were significantly stimulated by experimental warming. Retrospective analysis of flower production support field observations indicating that flower production is highly sensitive to annual variations in growing season temperatures. In contrast, shoot growth showed moderate responses to experimental warming. Records of past growth indicate that although vegetative production appears to be sensitive to annual variations in summer temperatures, the degree of responsiveness is much lower than for reproductive parameters. Net growth and reproduction were not stronly affected by natural or experimental variations in snowmelt timing, although phenology timing was significantly altered. The conservative growth response of Cassiope tetragona to short-term variations in climate is suggested to be related to constraints on plant phenology which may restrict flexibility in the period utilized by plants for aboveground growth. Preferential allocation of within-plant resources to reproductive structures during periods of ameliorated growing season climate may account for the observed strong reproductive responses to climate variations. Trade-offs betweeen growth and reproduction have important implications for predicting the long-term response of Cassiope tetragona to climate change. An understanding of within-plant allocation strategies is also important to the interpretation of past variations in growth and reproduction. Retrospective analysis of past Cassiope production is likely to be a very useful tool for investigating ecological relationships and past climate change.