The distribution of trees across urban areas of the UK has been shown to be uneven, with lower density residential areas containing many more trees and much higher tree cover than areas of higher density housing. However, in Greater Manchester, tree number within high density housing areas also varies substantially. This thesis sought to explore the reasons for this variation in tree cover, whether tree cover should be increased and if so, how. The research investigated a potential cause for the variation in number of trees and tree cover within high density housing areas – housing type – for the study area of western Greater Manchester. Eleven different types of high density housing were categorised and all high density housing within the study area was classified as one of these types. Within these housing types, the amount of tree cover was determined, along with the proportions of other surface types. The land uses where the trees were growing were also determined. Finally, the potential increases in tree cover were also calculated for each housing type by a simulated planting technique. Maximum surface temperatures and rainfall runoff were calculated using computer models, for both existing and potential tree cover in each housing type. It was found that urban tree cover varies from 1.6% in pre 1919 terraced housing that opens directly onto the road to 14.8% in 1960s walkway-style housing. Tree cover could theoretically be increased by at least 5% in all housing types, reducing maximum surface temperatures by at least 1°C. In housing types with less than 4% existing tree cover, maximum surface temperatures could be reduced by up to 4.5°C. The views of residents were determined using a postal questionnaire about urban trees sent to residents of 4 different types of street environment. Residents of all street types surveyed were very positive about urban trees; their attitudes were not affected by whether there are trees in their street or not. The vast majority of respondents considered trees important to their quality of life, and that cost to the council should not prevent tree planting. The views and practices around urban trees and greening by practitioners were determined by running a workshop and their recommendations to increase tree cover are presented. These include changes in funding to include money for tree maintenance after planting, the importance of a full tree inventory and innovative ways to raise funding for trees. The effectiveness of a community greening scheme at increasing tree cover was compared with two regeneration schemes. The community tree planting scheme was found to deliver tree planting much closer to the potential than regeneration schemes.

The spatial pattern of plants reflects biotic and abiotic factors, including interactions with surrounding environmental conditions and other plants. Appalachian heath systems are presently understudied regarding spatial point pattern research, despite representing a unique and biologically valuable ecosystem. In this study, we characterized the spatial pattern of three tree species distributions in the upland heath barrens on Cabin Mountain in Canaan Valley, West Virginia through fieldwork, statistical modeling, and the use of geographical information systems (GIS). The research objectives were to: 1) quantify the global and local spatial patterns of trees to infer biotic process, and 2) identify how tree spatial pattern varies with selected biophysical variables, including ground curvature and topographic wetness index, to understand potential relationships between ambient conditions and spatial pattern. The spatial statistics, Ripley's K-function and nearest neighbor analysis, presented a series of different interaction types reflected across size-growth classes and species where the null hypothesis was rejected for some pairs and supported in others. The selected biophysical variables had no significant relationship to spatial pattern at the site. These findings suggest a range of both intraspecific and interspecific interactions are taking place in the heath barrens of Cabin Mountain, where significant levels of facilitation are occurring among encroaching red maple and striped maple, while red spruce is in competition with both species of maple, and that relationships are formed outside the influence of topographic characteristics of the site. / Master of Science / The spatial pattern of plants reflects biotic and abiotic factors, including interactions with surrounding environmental conditions and other plants. Appalachian heath barrens are presently understudied in regard to spatial point pattern research, despite representing a unique and biologically valuable ecosystem. In this study, we characterized the spatial pattern of three tree species in the red spruce heath barrens on Cabin Mountain in Canaan Valley, West Virginia through fieldwork, statistical modeling, and the use of geographical information systems (GIS). The research objectives were to: 1) quantify demographics and the spatial pattern of trees to assess for ongoing plant interaction, and 2) understand whether tree spatial pattern is affected by selected biophysical variables, including ground curvature and topographic wetness index, to understand potential relationships between environmental conditions and spatial pattern. The results suggested a range of interactions were occurring across the plot, intraspecies, different species-pairs, and size-growth classes. Most notably, encroaching striped and red maple species, had a positive relationship, while red spruce and both maple species had largely competitive relationships. Both topographic wetness index and ground curvature had no significant relationship to spatial pattern at the site. These findings suggest a range of both intraspecific and interspecific interactions are taking place in the heath barrens of Cabin Mountain, indicating the possibility of conversion from red spruce heath barrens to deciduous forest, that this pattern is formed outside the influence of topographic characteristics of the site.

Probabilistic graphical modeling is a framework which can be used to succinctly<br>represent multivariate probability distributions of time series in terms of each time<br>series’s dependence on others. In general, it is computationally prohibitive to sta-<br>tistically infer an arbitrary model from data. However, if we constrain the model to<br>have a tree topology, the corresponding learning algorithms become tractable. The<br>expressive power of tree-structured distributions are low, since only n − 1 dependen-<br>cies are explicitly encoded for an n node tree. One way to improve the expressive<br>power of tree models is to combine many of them in a mixture model. This work<br>presents and uses simulations to validate extensions of the standard mixtures of trees<br>model for i.i.d data to the setting of time series data. We also consider the setting<br>where the tree mixture itself forms a hidden Markov chain, which could be better<br>suited for approximating time-varying seasonal data in the real world. Both of these<br>are evaluated on artificial data sets.<br><br>

Tesis por compendio / [EN] Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) is a new citrus pest in the Mediterranean basin. Nymphs of P. kellyanus refuge and feed on the surface of young fruitlets. This feeding habit causes rings of tissue scar around the apex as fruit mature and leads to economic losses because of the reduced market value of the affected fruit. Despite the worldwide distribution and economic importance of P. kellyanus, its biological control is still under development and chemical control is the only alternative for growers. In order to improve the integrated management of P. kellyanus we determined the seasonal trend of P. kellyanus nymphs during the period in which the young fruitlets are sensitive to thrips damage. We studied the diurnal distribution of ¿rst and second generation P. kellyanus nymphs, as well as, the spatial distribution within the tree of the nymphs and damages. These results will improve the sampling protocols and the insecticide applications. The seasonal trend (number of generations attacking the fruit) and damages of P. kellyanus nymphs depended on the orchards and years. This result emphasizes the importance of sampling weekly from petal until six weeks later. Furthermore, according to the data obtained, when there is a second generation of P. kellyanus nymphs, this is generally more damaging. Pezothrips kellyanus nymphs showed a clear preference for fruit located at the top of the trees, which coincided with the highest percentage of damaged fruit in this area. P. kellyanus nymphs were uniformly distributed and the cardinal directions and time of day does not seem to be an important factor to develop a sampling plan or to spray insecticides. The next objective was to determine the efficacy of three insecticides (chlorpyrifos, spinosad and spirotetramat) to control P. kellyanus nymphs. These insecticides were selected because of their different mode of action. Chlorpyrifos and spinosad significantly reduced the percentage of damaged fruit when there was one generation of nymphs. However, their persistence was not enough to prevent the attack of a second generation of nymphs. Spirotetramat had not a shock effect against this pest and it could not avoid the attack of a second generation. We analysed the side effects of these three insecticides on natural enemies present at the time of the treatment. Spinosad as spirotetramat negatively affected phytoseiids. Due to low populations of other natural enemies we could not assess the side effects on them. Therefore, we decided to study the side effects of these insecticides on coccinelids and parasitoids under laboratory conditions. Lethal and sublethal side effects of spirotetramat on adults and larvae of Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) were evaluated under laboratory conditions by topical application and by ingestion of treated individuals of Planococcus citri Risso (Hemiptera: Pseudococcidae). Spirotetramat resulted harmless when directly applied on larvae and adults of C. montrouzieri, since it did not affect survival, longevity, fecundity, egg hatching, and offspring survival. When larvae and adults of C. Montrouzieri were fed with treated prey, spirotetramat was also classified as harmless. We studied lethal and sublethal effects of spirotetramat, spinosad and chlorpyrifos on Aphytis melinus DeBach (Aphelinidae Hymenoptera), the main parasitoid of Aonidiella aurantii (Maskell) (Hemipteta: Diaspididae). For A. melinus adults, chlorpyrifos and spinosad were classified as toxic but spirotetramat resulted moderately toxic. For immature (larvae), chlorpyrifos was moderately toxic, spirotetramat was slightly toxic and spinosad resulted harmless. Takin into consideration these results, spirotetramat could be used against P. kellyanus in orchards where population levels are low and an application against A. aurantii is also need because this insecticide shows high efficacy against this pest. / [ES] Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) es actualmente una plaga más en los cítricos valencianos, cuyas ninfas, al alimentarse de la superficie de los frutos recién cuajados, producen unas escarificaciones circulares alrededor del pedúnculo que devalúan el valor del fruto en el mercado. Hoy en día, el control químico es prácticamente la única alternativa contra este trips. Para mejorar la gestión integrada de P. kellyanus es necesario un mayor conocimiento sobre su biología y ecología en campo. Para ello, se ha seguido la dinámica poblacional de las ninfas de P. kellyanus durante el periodo en que los frutos recién cuajados son más sensibles a los daños producidos por las ninfas. Se ha estudiado la distribución de la plaga dentro de los árboles y su movimiento a lo largo del día, factores necesarios para estimar la población de trips y para afinar las aplicaciones de productos fitosanitarios. Tanto la dinámica como los daños variaron según parcelas y años. Tras la caída de pétalos se observaron una o dos generaciones de ninfas que produjeron daños en los frutos. Resultado que subraya la necesidad de realizar muestreos semanales desde la caída de pétalos hasta incluso después del tratamiento contra la primera generación. Además, según los datos obtenidos, cuando se da una segunda generación de P. Kellyanus, ésta es más dañina para los frutos. Las ninfas de P. kellyanus mostraron una preferencia por los frutos situados en la parte alta de la copa, coincidiendo con el mayor número de frutos dañados en esta zona. La distribución de las ninfas fue uniforme en las cuatro orientaciones del árbol y a lo largo del día. Por lo tanto, estos factores no parecen ser claves a la hora de desarrollar un plan de muestreo o realizar aplicaciones fitosanitarias. A continuación se determinó la eficacia de tres insecticidas (clorpirifos, spinosad y spirotetramat), con diferente modo de acción, en el control de las ninfas de P. kellyanus. Clorpirifos y spinosad redujeron significativamente el porcentaje de frutos dañados cuando se dio una sola generación de ninfas P. Kellyanus, sin embargo no evitaron el ataque de una segunda generación de ninfas. Spirotetramat no presentó un efecto de choque y no evitó el segundo ataque. En estos trabajos de campo, se analizaron los efectos secundarios de los insecticidas sobre los enemigos naturales presentes en el momento de los tratamientos. Spinosad como spirotetramat afectaron negativamente a las poblaciones fitoseidos en campo. Debido a las bajas poblaciones del resto de enemigos naturales no pudo evaluarse los efectos secundarios sobre ellos y se estudiaron en condiciones de laboratorio sobre coccinélidos y parasitoides. Se determinaron los efectos letales y subletales de spirotetramat en adultos y larvas de Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae), por aplicación directa de los productos y por ingestión de presa, Planococcus citri Risso (Hemiptera: Pseudococcidae), previamente tratada por los productos. Spirotetramat resultó inocuo al aplicarse directamente sobre larvas o adultos de C. montrouzieri, y no afectó a la supervivencia, longevidad fecundidad, fertilidad y y supervivencia de la descendencia. Spirotetramat también resultó inocuo al alimentar a adultos y larvas de C. montrouzieri con presa previamente tratada. Se determinaron los efectos letales y subletales de los tres insecticidas sobre Aphytis melinus DeBach (Hymenoptera: Aphelinidae), principal parasitoide de Aonidiella aurantii (Maskell) (Hemipteta: Diaspididae) en cítricos. En adultos, clorpirifos y spinosad resultaron tóxicos mientras que spirotetramat resultó moderadamente tóxico. Sobre inmaduros de A. melinus, clorpirifos resultó moderadamente tóxico, spirotetramat ligeramente tóxico y spinosad inocuo. Así, spirotetramat se podría utilizar contra P. kellyanus en parcelas con niveles poblacionales bajos cuando deba tratarse también cont / [CA] Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) és, actualment, una plaga més dels cítrics valencians. Les nimfes es refugien i s'alimenten de la superfície dels fruits recentment quallats que produeix unes escarificacions circulars al voltant del peduncle del fruit i devaluen el seu valor al mercat. Hui en dia, el control químic és pràcticament l'única alternativa contra aquest trips. Per poder millorar la gestió integrada de P. kellyanus és necessari un major coneixement sobre la seua biologia i ecologia en camp. Per a això, s'ha avaluat la dinàmica poblacional de les nimfes de P. kellyanus durant el període on els fruits recentment quallats són més sensibles als danys produïts per les nimfes. A més, s'ha estudiat la distribució de la plaga dins dels arbres i el seu moviment al llarg del dia, factors necessaris per a estimar la població de trips i per afinar les aplicacions de productes fitosanitaris. Tant la dinàmica com els danys van variar segons parcel¿les i anys, després de la caiguda de pètals es van observar una o dues generacions de nimfes que van produir danys als fruits. Aquest resultat subratlla la necessitat de realitzar mostrejos setmanals des de la caiguda de pètals fins i tot després del tractament contra la primera generació. Segons les dades obtingudes, quan es dóna una segona generació de P. kellyanus, aquesta és més perjudicial per als fruits. Les nimfes van mostrar un clara preferència pels fruits situats a la part alta de la copa, coincidint amb el major nombre de fruits danyats en aquesta zona. No obstant això, la distribució de les nimfes va ser uniforme en les quatre orientacions de l'arbre i la seva abundància tampoc va variar al llarg del dia. Per tant, son factors que no semblen ser claus a l'hora de desenvolupar un pla de mostreig o realitzar aplicacions fitosanitàries. El següent objectiu va ser determinar l'eficàcia de tres insecticides (clorpirifos, spinosad i spirotetramat), amb acció diferent, en el control de les nimfes de P. kellyanus. Clorpirifos i spinosad van reduir significativament el percentatge de fruits danyats quan es va donar una sola generació de nimfes, però no varen evitar l'atac d'una segona generació de nimfes. Spirotetramat no va presentar un efecte de xoc contra aquesta plaga i tampoc va evitar l'atac d'una segona generació. En aquests treballs de camp, se va analitzar els efectes secundaris d'aquests tres insecticides sobre els enemics naturals presents en el moment dels tractaments. Spinosad i spirotetramat van afectar negativament les poblacions fitoseids en camp. Com varen ser baixes les poblacions de la resta d'enemics naturals es va estudiar els efectes secundaris sobre coccinélids i parasitoids en condicions de laboratori. Es varen determinar els efectes letals i subletals de spirotetramat en adults i larves de Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) per aplicació directa dels productes i per ingestió de presa, Planococcus citri Risso (Hemiptera: Pseudococcidae), prèviament tractada pels productes. Spirotetramat va resultar innocu a la aplicació directa sobre larves o adults de C. montrouzieri, no va afectar la supervivència, longevitat fecunditat, fertilitat i supervivència de la descendència. I el mateix quan adults i larves de van ser alimentats amb presa prèviament tractada. Finalment, es van determinar els efectes letals i subletals dels tres insecticides sobre Aphytis melinus DeBach (Hymenoptera: Aphelinidae), principal parasitoid de Aonidiella aurantii (Maskell) (Hemipteta: Diaspididae) en cítrics. En adults, clorpirifos i spinosad van resultar tòxics, spirotetramat va resultar moderadament tòxic. Sobre immadurs de A melinus, clorpirifos va resultar moderadament tòxic, spirotetramat lleugerament tòxic i spinosad innocu. Així, spirotetramat es podria utilitzar contra P. kellyanus en parcel¿les amb nivells poblacionals baixos aprofitant el tractament contra A. aurantii al p / Planes Insa, L. (2016). BASES PARA LA GESTIÓN INTEGRADA DE PEZOTHRIPS KELLYANUS (BAGNALL) (THYSANOPTERA: THRIPIDAE) EN CÍTRICOS [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/63676 / Compendio