Competition may explain the fine-scale spatial patterns and genetic structure of two co-occurring plant congeners

1.���The spatial distribution of individual plants within a population and the population���s genetic structure are determined by several factors, like dispersal, reproduction mode or biotic interactions. The role of interspecific interactions in shaping the spatial genetic structure of plant populations remains largely unknown. 2.���Species with a common evolutionary history are known to interact more closely with each other than unrelated species due to the greater number of traits they share. We hypothesize that plant interactions may shape the fine genetic structure of closely related congeners. 3.���We used spatial statistics (georeferenced design) and molecular techniques (ISSR markers) to understand how two closely related congeners, Thymus vulgaris (widespread species) and T. loscosii (narrow endemic) interact at the local scale. Specific cover, number of individuals of both study species and several community attributes were measured in a 10 �� 10 m plot. 4.���Both species showed similar levels of genetic variation, but differed in their spatial genetic structure. Thymus vulgaris showed spatial aggregation but no spatial genetic structure, while T. loscosii showed spatial genetic structure (positive genetic autocorrelation) at short distances. The spatial pattern of T. vulgaris��� cover showed significant dissociation with that of T. loscosii. The same was true between the spatial patterns of the cover of T. vulgaris and the abundance of T. loscosii and between the abundance of each species. Most importantly, we found a correlation between the genetic structure of T. loscosii and the abundance of T. vulgaris: T. loscosii plants were genetically more similar when they were surrounded by a similar number of T. vulgaris plants. 5.���Synthesis. Our results reveal spatially complex genetic structures of both congeners at small spatial scales. The negative association among the spatial patterns of the two species and the genetic structure found for T. loscosii in relation to the abundance of T. vulgaris indicate that competition between the two species may account for the presence of adapted ecotypes of T. loscosii to the abundance of a competing congeneric species. This suggests that the presence and abundance of close congeners can influence the genetic spatial structure of plant species at fine scales.

Fine spatial pattern of an epiphytic lichen species is affected by habitat conditions in two forest types in the Iberian Mediterranean region

Persistence and abundance of species is determined by habitat availability and the ability to disperse and colonize habitats at contrasting spatial scales. Favourable habitat fragments are also heterogeneous in quality, providing differing opportunities for establishment and affecting the population dynamics of a species. Based on these principles, we suggest that the presence and abundance of epiphytes may reflect their dispersal ability, which is primarily determined by the spatial structure of host trees, but also by host quality. To our knowledge there has been no explicit test of the importance of host tree spatial pattern for epiphytes in Mediterranean forests. We hypothesized that performance and host occupancy in a favourable habitat depend on the spatial pattern of host trees, because this pattern affects the dispersal ability of each epiphyte and it also determines the availability of suitable sites for establishment. We tested this hypothesis using new point pattern analysis tools and generalized linear mixed models to investigate the spatial distribution and performance of the epiphytic lichen Lobaria pulmonaria, which inhabits two types of host trees (beeches and Iberian oaks). We tested the effects on L. pulmonaria distribution of tree size, spatial configuration, and host tree identity. We built a model including tree size, stand structure, and several neighbourhood predictors to understand the effect of host tree on L. pulmonaria. We also investigated the relative importance of spatial patterning on the presence and abundance of the species, independently of the host tree configuration. L. pulmonaria distribution was highly dependent on habitat quality for successful establishment, i.e., tree species identity, tree diameter, and several forest stand structure surrogates. For beech trees, tree diameter was the main factor influencing presence and cover of the lichen, although larger lichen-colonized trees were located close to focal trees, i.e., young trees. However, oak diameter was not an important factor, suggesting that bark roughness at all diameters favoured lichen establishment. Our results indicate that L. pulmonaria dispersal is not spatially restricted, but it is dependent on habitat quality. Furthermore, new spatial analysis tools suggested that L. pulmonaria cover exhibits a distinct pattern, although the spatial pattern of tree position and size was random.

Fine spatial pattern of an epiphytic lichen species is affected by habitat conditions in two forest types in the Iberian Mediterranean region

Persistence and abundance of species is determined by habitat availability and the ability to disperse and colonize habitats at contrasting spatial scales. Favourable habitat fragments are also heterogeneous in quality, providing differing opportunities for establishment and affecting the population dynamics of a species. Based on these principles, we suggest that the presence and abundance of epiphytes may reflect their dispersal ability, which is primarily determined by the spatial structure of host trees, but also by host quality. To our knowledge there has been no explicit test of the importance of host tree spatial pattern for epiphytes in Mediterranean forests. We hypothesized that performance and host occupancy in a favourable habitat depend on the spatial pattern of host trees, because this pattern affects the dispersal ability of each epiphyte and it also determines the availability of suitable sites for establishment. We tested this hypothesis using new point pattern analysis tools and generalized linear mixed models to investigate the spatial distribution and performance of the epiphytic lichen Lobaria pulmonaria, which inhabits two types of host trees (beeches and Iberian oaks). We tested the effects on L. pulmonaria distribution of tree size, spatial configuration, and host tree identity. We built a model including tree size, stand structure, and several neighbourhood predictors to understand the effect of host tree on L. pulmonaria. We also investigated the relative importance of spatial patterning on the presence and abundance of the species, independently of the host tree configuration. L. pulmonaria distribution was highly dependent on habitat quality for successful establishment, i.e., tree species identity, tree diameter, and several forest stand structure surrogates. For beech trees, tree diameter was the main factor influencing presence and cover of the lichen, although larger lichen-colonized trees were located close to focal trees, i.e., young trees. However, oak diameter was not an important factor, suggesting that bark roughness at all diameters favoured lichen establishment. Our results indicate that L. pulmonaria dispersal is not spatially restricted, but it is dependent on habitat quality. Furthermore, new spatial analysis tools suggested that L. pulmonaria cover exhibits a distinct pattern, although the spatial pattern of tree position and size was random.

Advanced characterization of a coffee fermenting tank by multi-distributed wireless sensors: spatial interpolation and phase diagrams.

In coffee processing the fermentation stage is considered one of the critical operations by its impact on the final quality of the product. However, the level of control of the fermentation process on each farm is often not adequate; the use of sensorics for controlling coffee fermentation is not common. The objective of this work is to characterize the fermentation temperature in a fermentation tank by applying spatial interpolation and a new methodology of data analysis based on phase space diagrams of temperature data, collected by means of multi-distributed, low cost and autonomous wireless sensors. A real coffee fermentation was supervised in the Cauca region (Colombia) with a network of 24 semi-passive TurboTag RFID temperature loggers with vacuum plastic cover, submerged directly in the fermenting mass. Temporal evolution and spatial distribution of temperature is described in terms of the phase diagram areas which characterizes the cyclic behaviour of temperature and highlights the significant heterogeneity of thermal conditions at different locations in the tank where the average temperature of the fermentation was 21.2 ��C, although there were temperature ranges of 4.6��C, and average spatial standard deviation of ��1.21��C. In the upper part of the tank we found high heterogeneity of temperatures, the higher temperatures and therefore the higher fermentation rates. While at the bottom, it has been computed an area in the phase diagram practically half of the area occupied by the sensors of the upper tank, therefore this location showed higher temperature homogeneity

Advanced Characterisation of a Coffee Fermenting Tank by Multi-distributed Wireless Sensors: Spatial Interpolation and Phase Space Graphs

The fermentation stage is considered to be one of the critical steps in coffee processing due to its impact on the final quality of the product. The objective of this work is to characterise the temperature gradients in a fermentation tank by multi-distributed, low-cost and autonomous wireless sensors (23 semi-passive TurboTag�� radio-frequency identifier (RFID) temperature loggers). Spatial interpolation in polar coordinates and an innovative methodology based on phase space diagrams are used. A real coffee fermentation process was supervised in the Cauca region (Colombia) with sensors submerged directly in the fermenting mass, leading to a 4.6 ��C temperature range within the fermentation process. Spatial interpolation shows a maximum instant radial temperature gradient of 0.1 ��C/cm from the centre to the perimeter of the tank and a vertical temperature gradient of 0.25 ��C/cm for sensors with equal polar coordinates. The combination of spatial interpolation and phase space graphs consistently enables the identification of five local behaviours during fermentation (hot and cold spots).

Patrones y procesos espaciales en poblaciones y comunidades vegetales: nuevas herramientas e hip��tesis

Generalmente los patrones espaciales de puntos en ecolog��a, se definen en el espacio bi-dimensional, donde cada punto representado por el par ordenado (x,y), resume la ubicaci��n espacial de una planta. La importancia de los patrones espaciales de plantas radica en que proceden como respuesta ante importantes procesos ecol��gicos asociados a la estructura de una poblaci��n o comunidad. Tales procesos incluyen fen��menos como la dispersi��n de semillas, la competencia por recursos, la facilitaci��n, respuesta de las plantas ante alg��n tipo de estr��s, entre otros. En esta tesis se eval��an los factores y potenciales procesos subyacentes, que explican los patrones de distribuci��n espacial de la biodiversidad vegetal en diferentes ecosistemas como bosque mediterr��neo, bosque tropical y matorral seco tropical; haciendo uso de nuevas metodolog��as para comprobar hip��tesis relacionadas a los procesos espaciales. En este trabajo se utilizaron dos niveles ecol��gicos para analizar los procesos espaciales, el nivel de poblaci��n y el nivel de comunidad, con el fin de evaluar la importancia relativa de las interacciones intraespec��ficas e interespec��ficas. Me centr�� en el uso de funciones estad��sticas que resumen los patrones de puntos para explorar y hacer inferencias a partir de datos espaciales, empezando con la construcci��n de un nuevo modelo nulo para inferir variantes del s��ndrome de dispersi��n de una planta par��sita en Espa��a central. Se analiz�� la dependencia de los patrones espaciales tanto de los hospedantes afectados como de los no-afectados y se observ�� fuerte dependencia a peque��a y mediana distancia. Se utilizaron dos funciones (kernel) para simular la dispersi��n de la especie par��sita y se identific�� consistencia de estos modelos con otros s��ndromes de dispersi��n adicionalmente a la autodispersi��n. Un segundo tema consisti�� en desarrollar un m��todo ANOVA de dos v��as? para patrones de puntos replicados donde el inter��s se concentr�� en evaluar la interacci��n de dos factores. Este m��todo se aplic�� a un caso de estudio que consiti�� en analizar la influencia de la topograf��a y la altitud sobre el patr��n espacial de un arbusto dominante en matorral seco al sur del Ecuador, cuyos datos provienen de patrones de puntos replicados basados en dise��o. Partiendo de una metodolog��a desarrollada para procesos uni-factoriales, se construy�� el m��todo para procesos bi-factoriales y as�� poder evaluar el efecto de interacci��n. Se observ�� que la topograf��a por s�� sola as�� como la interacci��n con la altitud presentaron efecto significativo sobre la formaci��n del patr��n espacial. Un tercer tema fue identificar la relaci��n entre el patr��n espacial y el s��ndrome de dispersi��n de la comunidad vegetal en el bosque tropical de la Isla de Barro Colorado (BCI), Panam��. Muchos estudios se han desarrollado en este bosque tropical y algunos han analizado la relaci��n s��ndrome-patr��n espacial, sin embargo lo novedoso de nuestro estudio es que se evaluaron un conjunto amplio de modelos (114 modelos) basados en procesos que incorporan la limitaci��n de la dispersi��n y la heterogeneidad ambiental, y eval��an el efecto ��nico y el efecto conjunto, para posteriormente seleccionar el modelo de mejor ajuste para cada especie. M��s de la mitad de las especies presentaron patr��n espacial consistente con el efecto conjutno de la limitaci��n de la dispersi��n y heterogeneidad ambiental y el porcentaje restante de especies revel�� en forma equitativa el efecto ��nico de la heterogeneidad ambiental y efecto ��nico de limitaci��n de la dispersi��n. Finalmente, con la misma informaci��n del bosque tropical de BCI, y para entender las relaciones que subyacen para mantener el equilibrio de la biodiversidad, se desarroll�� un ��ndice de dispersi��n funcional local a nivel de individuo, que permita relacionar el patr��n espacial con cuatro rasgos funcionales clave de las especies. Pese a que muchos estudios realizados involucran esta comunidad con la teor��a neutral, se encontr�� que el ensamble de la comunidad de BCI est�� afectado por limitaciones de similaridad y de h��bitat a diferentes escalas. ABSTRACT Overall the spatial point patterns in ecology are defined in two-dimensional space, where each point denoted by the (x,y) ordered pair, summarizes the spatial location of a plant. The spatial point patterns are essential because they arise in response to important ecological processes, associated with the structure of a population or community. Such processes include phenomena as seed dispersal, competition for resources, facilitation, and plant response to some type of stress, among others. In this thesis, some factors and potential underlying processes were evaluated in order to explain the spatial distribution patterns of plant biodiversity. It was done in different ecosystems such as Mediterranean forest, tropical forest and dry scrubland. For this purpose new methodologies were used to test hypothesis related to spatial processes. Two ecological levels were used to analyze the spatial processes, at population and community levels, in order to assess the relative importance of intraspecific and interspecific interactions. I focused on the use of spatial statistical functions to summarize point patterns to explore and make inferences from spatial data, starting with the construction of a new null model to infer variations about the dispersal syndrome of a parasitic plant in central Spain. Spatial dependence between point patterns in a multivariate point process of affected and unaffected hosts were analyzed and strong dependence was observed at small and medium distance. Two kernel functions were used to simulate the dispersion of parasitic plant and consistency of these models with other syndromes was identified, in addition to ballistic dispersion. A second issue was to analyze altitude and topography effects on the spatial population structure of a dominant shrub in the dry ecosystem in southern Ecuador, whose data come from replicated point patterns design-based. Based on a methodology developed for uni-factorial process, a method for bi-factorial processes was built to assess the interaction effect. The topography alone and interacting with altitude showed significant effect on the spatial pattern of shrub. A third issue was to identify the relationship between the spatial pattern and dispersal syndromes of plant community in the tropical forest of Barro Colorado Island (BCI), Panam��. Several studies have been developed in this tropical forest and some focused on the spatial pattern-syndrome relationship; however the novelty of our study is that a large set of models (114 models) including dispersal limitation and environmental heterogeneity were evaluated, used to identify the only and joint effect to subsequently select the best fit model for each species. Slightly more than fifty percent of the species showed spatial pattern consistent with only the dispersal limitation, and the remaining percentage of species revealed the only effect of environmental heterogeneity and habitat-dispersal limitation joined effect, equitably. Finally, with the same information from the tropical forest of BCI, and to understand the relationships underlying for balance of biodiversity, an index of the local functional dispersion was developed at the individual level, to relate the spatial pattern with four key functional traits of species. Although many studies involve this community with neutral theory, the assembly of the community is affected by similarity and habitat limitations at different scales.

Estructura espacial y din��mica del bosque montano del sur del Ecuador. Interacciones bi��ticas y limitaciones abi��ticas

Muchos estudios han descrito la composici��n y diversidad de los bosques montanos tropicales, pero los patrones espaciales y las diferentes tipos de relaciones de estos, entre especies o entre grupos funcionales ha sido poco documentada. El presente trabajo se realiz�� en tres parcelas completamente censadas del bosque de la Estaci��n Biol��gica ���Chamusquin��� (Zamora Chinchipe, Ecuador), y se plantea como objetivo principal conocer la estructura espacial y din��mica del bosque montano tropical del sur del Ecuador, as�� como las interacciones bi��ticas y limitaciones abi��ticas que influyen en esta din��mica, para ello se plante�� cuatro objetivos de estudio que son: conocer los patrones espaciales de los gremios ecol��gicos dentro de la zona de estudio; conocer la influencia de la dependencia negativa de la densidad sobre dos especies de helechos arborescentes (Cyatheaceae); conocer si existen especies o grupos ecol��gicos acumuladoras o repulsoras de diversidad en el ��rea de estudio; y conocer c��mo influyen la diversidad filogen��tica y la densidad del vecindario en la incidencia de herbivor��a y parasitismo sobre las fases iniciales del establecimiento forestal (brinzales) as�� como en la supervivencia de los mismos Como paso previo para el an��lisis del resto de objetivos, dentro de cada parcela se marcaron todos los individuos con DAP ���5 cm y se tomaron sus coordenadas (X, Y). Adem��s se tomaron datos de variables superficiales y muestras del suelo. Las especies encontradas se clasificaron de acuerdo a sus caracter��sticas biol��gicas, asign��ndolas a cada uno de los cuatro gremios forestales usualmente distinguidos en los bosques tropicales: tolerantes a la sombra (TS), tolerantes parciales a la sombra (TPS), pioneras de vida larga (PVL) y pioneras de vida corta (PVC). Para el estudio del primer objetivo tas se emplearon funciones K de Ripley inhomog��neas, ajustando la heterogeneidad en base a la variaci��n espacial de las variables ambientales registradas . Los resultados demostraron que tanto la frecuencia relativa como el patr��n espacial de las diferentes estrategias funcionales var��an a lo largo de la sucesi��n y que ��ste adem��s est�� influido por la variaci��n ambiental. En adici��n, tanto el patr��n espacial como la respuesta a la variaci��n ambiental de los diferentes gremios es distinta entre adultos y juveniles. Todo ello sugiere que el ensamblaje de la diversidad en los bosque montanos andinos est�� controlado por procesos deterministas m��s que por procesos neutrales. Para responder el segundo objetivo se estudiaron los efectos de la dependencia negativa de la densidad (DND) y la heterogeneidad ambiental en las poblaciones de dos especies de helechos arborescentes abundantes, Cyathea caracasana y Alsophila engelii, y c��mo estos efectos cambian a trav��s de un gradiente sucesional. Los patrones de especies albergan informaci��n sobre procesos tales como la competencia que puede ser revelado f��cilmente utilizando t��cnicas de an��lisis de patrones punto. Sin embargo, su detecci��n puede ser dif��cil debido a los efectos de factores de confusi��n heterogeneidad del h��bitat. Aqu��, empleamos funciones K y funciones de correlaci��n de par homog��neas y no homog��neas para cuantificar el cambio en el patr��n espacial de diferentes clases de tama��o con un dise��o de casos-controles para estudiar las asociaciones entre helechos arborescentes j��venes y adultos. Usando estimaciones espaciales de la biomasa de los cuatro tipos de gremios ecol��gicos (PVC, PVL, TPS, TS) como covariables, hemos ajustado modelos de Poisson heterog��neos a los patrones de puntos de de los helechos juveniles y los adultos y hemos explorado adem��s la existencia de dependencia del h��bitat en estos patrones. Nuestro estudio revel�� efectos de la DND para C. caracasana y un fuerte filtrado ambiental que subyace al patr��n de A. engelii. Encontramos tambi��n que las poblaciones de adultos y juveniles de ambas especies respondieron de manera diferente a la heterogeneidad del h��bitat y en la mayor��a de los casos esta heterogeneidad se asoci�� con la distribuci��n espacial de la biomasa de los cuatro tipos de gremios. Estos resultados muestran la eficacia de controlar los efectos de la heterogeneidad ambiental para evitar su confusi��n con los patrones derivados de interacciones biol��gicas cuando se estudia la DND y demuestran la utilidad de los mapas de covariables derivados de comunidades biol��gicas como resumen de la heterogeneidad ambiental. Para nuestro tercer objetivo nos centramos en explorar c��mo influyen las especies m��s abundantes en la organizaci��n espacial de la diversidad a lo largo de un gradiente sucesional en el bosque montano del sur del Ecuador. Para ello utilizamos la funci��n ISAR (Individual Species Area Relationship). Encontramos que la frecuencia de especies neutras, repulsoras y acumuladoras de diversidad taxon��mica var��a dependiendo del grado de sucesi��n. Adem��s se comprob�� que la mayor��a de los gremios forestales se comport�� de forma neutral, pero la proporci��n de acumuladores, aument�� al avanzar la sucesi��n hacia estados m��s maduros, lo que indica el establecimiento de fuertes procesos competitivos a medida que avanza la sucesi��n y la mayor importancia del papel de las especies individuales en dichos estados. Finalmente, examinamos el efecto de la vecindad taxon��mica y filogen��tica, as�� como la estrategia de vida, sobre la incidencia de la herbivor��a y el parasitismo en las poblaciones de brinzales de tres fragmentos forestales en una secuencia sucesional del bosque montano h��medo. Evaluamos adem��s los efectos de herbivor��a, parasitismo, estrategia de vida y diferentes indicadores de la vecindad sobre la supervivencia de los brinzales. Por ��ltimo contrastamos la posible existencia de una tendencia compensatoria de la comunidad (CCT) a nivel de fragmento forestal. Nuestros an��lisis no consiguieron detectar una CCT pero si pusieron de manifiesto la existencia de efectos locales de dependencia negativa de la densidad. Por ejemplo, la presencia de herbivor��a y parasitismo sobre los brinzales se relacion�� significativamente con una menor supervivencia de estos. Por otro lado, indicadores del efecto de la vecindad como la densidad de brinzales del mismo g��nero y el ��rea basal de ��rboles vecinos del mismo g��nero incrementaron la prevalencia de la herbivor��a o el parasitismo en los brinzales. El incremento de la incidencia de la herbivor��a o el parasitismo no est�� exclusivamente ligado a tener una vecindad taxon��micamente id��ntica (vecinos de la misma especie) sino que categor��as taxon��micas m��s laxas como el "g��nero" o simplemente relaciones de semejanza filogen��tica son capaces de predecir los efectos negativos de la vecindad. Los efectos detectados variaron en los diferentes grupos funcionales distinguidos. Los resultados que hemos obtenido en este trabajo parecen indicar que el funcionamiento de las comunidades de brinzales del bosque montano tropical no difiere mucho del reportado para comunidades de pl��ntulas en otros bosques tropicales y cumple las predicciones de la hip��tesis de Janzen y Connell, aunque matizadas por la mayor resistencia de los brinzales al efecto de herbivor��a y parasitismo. ABSTRACT Many studies have described the composition and diversity of tropical montane forests, but the different spatial patterns and types of relationships between species or between functional groups has been poorly documented. This work was made in three completely surveyed forest plots at Biological Station "Chamusquin" (Zamora Chinchipe, Ecuador). Our main objective was to know the spatial structure and dynamics of the tropical montane forest in southern Ecuador, as well as the biotic interactions and abiotic constraints affecting this dynamic. More specifically, we aimed to understand the spatial patterns of ecological guilds; to explore the influence of negative density dependence on two species of tree ferns (Cyatheaceae); to determine whether some species or ecological groups structure spatially plant diversity in these forests; and to test the effects of biological neighborhood on the incidence of herbivory and parasitism and on the survival of saplings. We mapped within each plot all trees with DBH ���5 cm. Besides, surface data variables and soil samples they were taken. The species found were classified according to their biological characteristics in four forest guilds: shade-tolerant (ST), partial shade tolerant (PST), long-lived pioneer (LLP) and short-lived pioneer (SLP). To analyze the spatial patterns of the ecological guilds, we employed the inhomogeneous version of Ripley's K-function and adjusted heterogeneity surfaces based on the spatial variation of the measured environmental variables. The results showed that both the relative frequency of each functional guild as well as their spatial pattern varied throughout succession and that the spatial pattern is explained by environmental variation. In addition, both spatial pattern and the response to spatial variation of each guild varied throughout ontogeny. All in all suggest that diversity assembly in the studied forests is ruled by deterministic instead of neutral processes. We also addressed the negative effects of density dependence (NDD) and environmental heterogeneity in populations of two species of abundant tree ferns, Cyathea caracasana and Alsophila engelii, and how these effects change across a successional gradient.. Here, we used homogeneous and inhomogeneous K and pair-correlation functions to quantify the change in the spatial pattern of different size classes with a case-control design to study associations between young and adult tree ferns. Using spatial estimates of the biomass of the four types of ecological guilds (SLP, LLP, PST, ST) as co-variables, we fitted heterogeneous Poisson models to juvenile and adult tree fern point patterns and explored the existence of habitat dependence. Our study revealed NDD effects for C. caracasana and strong environmental filtering underlying the pattern of A. engelii. We found that adult and juvenile populations of both species responded differently to habitat heterogeneity and in most cases this heterogeneity was associated with the spatial distribution of biomass of the four functional tree types. These findings show the effectiveness of factoring out environmental heterogeneity to avoid confounding factors when studying NDD and demonstrate the usefulness of covariate maps derived from mapped communities. For our third objective we focused on exploring how the most abundant species influence the spatial organization of tree diversity in these forests. For this, we used the individual species-area relationship function (ISAR). We found that the proportion of accumulator, repeller and neutral species, varied depending on the degree of succession. We found also that most guilds behaved neutrally but the proportion of accumulator guilds increased as succession advanced to more mature stages. This point, to the existence of strong competitive effects mediated by individual species in these mature forests. Finally, we examined the effects of life strategies and taxonomic and phylogenetic neighborhood on the incidence of herbivory and parasitism in the communities of saplings in the same forest fragments. We evaluated also the effects of life strategies, herbivory, parasitism and some indicators of neighborhood on sapling survival. Finally we tested for the existences of a compensatory community trend at plot scale. We did not found a CCT but we found proof of local NND effects. For instance, the prevalence of herbivory and parasitism were related to lower sapling survival. On the other hand the density of con-generic saplings and the basal area of neighbor con-generic trees were related to a higher prevalence of herbivory or parasitism in the saplings. We demonstrated that the increase in the prevalence of herbivory or parasitism it s not exclusive of a conspecific neighborhood but instead larger taxonomic categories such as "genus" or simple phylogenetic relationships are also able to predict NND effects. The NND effects varied among functional guilds. Our results show that the dynamic of sapling communities in Ecuadorian montane forests is similar to seedling dynamics in other tropical forest and follows the predictions of Janzen-Connell hypothesis, although softened by the strong resilience of saplings in comparison to seedlings.

Juvenile���adult tree associations in a continental Mediterranean ecosystem: no evidence for sustained and general facilitation at increased aridity

Question: How do tree species identity, microhabitat and water availability affect inter- and intra-specific interactions between juvenile and adult woody plants? Location: Continental Mediterranean forests in Alto Tajo Natural Park, Guadalajara, Spain. Methods: A total of 2066 juveniles and adults of four co-occurring tree species were mapped in 17 plots. The frequency of juveniles at different microhabitats and water availability levels was analysed using log-linear models. We used nearest-neighbour contingency table analysis of spatial segregation and J-functions to describe the spatial patterns. Results: We found a complex spatial pattern that varied according to species identity and microhabitat. Recruitment was more frequent in gaps for Quercus ilex, while the other three species recruited preferentially under shrubs or trees depending on the water availability level. Juveniles were not spatially associated to conspecific adults, experiencing segregation from them inmany cases. Spatial associations, both positive and negative, were more common at higher water availability levels. Conclusions: Our results do not agree with expectations from the stressgradient hypothesis, suggesting that positive interactions do not increase in importance with increasing aridity in the study ecosystem. Regeneration patterns are species-specific and depend on microhabitat characteristics and dispersal strategies. In general, juveniles do not look for conspecific adult protection. This work contributes to the understanding of species co-existence, proving the importance of considering a multispecies approach at several plots to overcome limitations of simple pair-wise comparisons in a limited number of sites.

On the spatial distribution of woody plant species in a tropical montane cloud forest

Abstract The cloud forest is a special type of forest ecosystem that depends on suitable conditions of humidity and temperature to exist; hence, it is a very fragile ecosystem. The cloud forest is also one of the richest ecosystems in terms of species diversity and rate of endemism. However, today, it is one of the most threatened ecosystems in the world. Little is known about tree species distribution and coexistence among cloud forest trees. Trees are essential to understanding ecosystem functioning and maintenance because they support the ecosystem in important ways. For this dissertation, an analysis of woody plant species distribution at a small scale in a north-Peruvian Andean cloud forest was performed, and some of the factors implicated in the observed patterns were identified. Towards that end, different natural factors acting on species distribution within the forest were investigated: (i) intra-specific arrangements, (ii) heterospecific spatial relationships and (iii) relationships with external environmental factors. These analyses were conducted first on standing woody plants and then on seedlings. The woody plants were found to be clumped in the forest, either considering all the species together or each species separately. However, each species presented a specific pattern and specific spatial relationship among different-age individuals. Dispersal mode, growth form and shade tolerance played roles in the final distribution of the species. Furthermore, spatial associations among species, either positive or negative, were observed. These associations were more numerous when considering individuals of the interacting species at different developmental stages, i.e., younger individuals from one species and older individuals from another. Accordingly, competition and facilitation are asymmetric processes and vary throughout the life of an individual. Moreover, some species appear to prefer certain habitat conditions and avoid other habitats. The habitat definition that best explains species distribution is that which includes both environmental and stand characteristics; thus, a combination of these factors is necessary to understanding species' niche preferences. Seedling distribution was also associated with habitat conditions, but these conditions explained less than the 30% of the spatial variation. The position of conspecific adult individuals also affected seedling distribution; although the seedlings of many tree species avoid the vicinity of conspecifics, a few species appeared to prefer the formation of cohorts around their parent trees. The importance of habitat conditions and distance dependence with conspecifics varied among regions within the forest as well as on the developmental stage of the stand. The results from this thesis suggest that different species can coexist within a given space, forming a ���puzzle��� of species as a result of the intra- and interspecific spatial relationships along with niche preferences and adaptations that operate at different scales. These factors not only affect each species in a different way, but specific preferences also vary throughout species' lifespans. Resumen Resumen El bosque de niebla es uno de los ecosistemas m��s amenazados del mundo adem��s de ser uno de los m��s fr��giles. Son formaciones azonales que dependen de la existencia de unas condiciones de humedad y temperatura que permitan la formaci��n de nubes que cubran el bosque; lo que dificulta en gran medida su conservaci��n. Tambi��n es uno de los ecosistemas con mayor riqueza de especies adem��s de tener uno de los mayores porcentajes de endemismos. Uno de los aspectos m��s importantes para entender el ecosistema, es identificar y entender los elementos que lo componen y los mecanismos que regulan las relaciones entre ellos. Los ��rboles son el soporte del ecosistema. Sin embargo, apenas hay informaci��n sobre la distribuci��n y coexistencia de los ��rboles en los bosques de niebla. Esta tesis presenta un an��lisis de la distribuci��n a peque��a escala de las plantas le��osas en un bosque de niebla situado en la cordillera andina del norte de Per��; as�� como el an��lisis de algunos de los factores que pueden estar implicados en que se origine la distribuci��n observada. Para este prop��sito se estudia c��mo influyen factores de diferente naturaleza en la distribuci��n de las especies (i) organizaci��n intra-espec��fica (ii) relaciones espaciales heterospec��ficas y (iii) relaci��n con factores ambientales externos. En estos an��lisis se estudiaron primero las plantas j��venes y las adultas, y despu��s las pl��ntulas. Los ��rboles aparecieron agregados en el bosque, tanto considerando todos a la vez como cuando se estudi�� cada especie por separado. Sin embargo, cada especie mostr�� un patr��n distinto as�� como una particular relaci��n espacial entre individuos j��venes y adultos. El modo de dispersi��n, la forma de vida y la tolerancia de la especies estuvieron relacionados con el patr��n general observado. Se vio tambi��n que ciertas especies aparec��an relacionadas con otras, tanto de forma positiva (compartiendo zonas) como negativa (apareciendo en ��reas distintas). Las asociaciones fueron mucho m��s numerosas cuando se consideraron los pares de especies en diferente estado de desarrollo, es decir, individuos j��venes de una especie e individuos mayores de la otra. Eso indicar��a que los procesos de competencia y facilitaci��n son asim��tricos y adem��s var��an durante la vida de la planta. Por otro lado, algunas especies aparecen preferentemente bajo ciertas condiciones de h��bitat y evitan otras. La definici��n de h��bitat a la que mejor responden las especies es cuando se incluyen tanto variables ambientales como de masa; as�� que ambos tipos de variables son necesarias para entender la preferencia de las especies por ciertos nichos. La distribuci��n de las pl��ntulas tambi��n estuvo relacionada con condiciones de h��bitat, pero eso s��lo llegaba a explicar hasta un 30% de la variabilidad espacial. La posici��n de los adultos de la misma especie tambi��n afect�� a la distribuci��n de las pl��ntulas. En bastantes especies las pl��ntulas evitan la cercan��a de adultos de su misma especie, padres potenciales, aunque algunas especies aisladas mostraron el patr��n contrario y aparecieron preferentemente en las mismas ��reas que sus padres. La importancia de las condiciones de h��bitat y posici��n de los adultos en la disposici��n de las pl��ntulas var��a de una zona a otra del bosque y adem��s tambi��n var��a seg��n el estado de desarrollo de la masa.

Territory and the governmentalisation of social reproduction: parliamentary enclosure and spatial rationalities in the transition from feudalism to capitalism

Recent applications of Foucauldian categories in geography, spatial history and the history of town planning have opened up interesting new perspectives, with respect to both the evolution of spatial knowledge and the genealogy of territorial techniques and their relation to larger socio-political projects, that would be enriched if combined with other discursive traditions. This article proposes to conceptualise English parliamentary enclosureea favourite episode for Marxist historiography, frequently read in a strictly materialist fashioneas a precedent of a new form of sociospatial governmentality, a political technology that inaugurates a strategic manipulation of territory for social change on the threshold between feudal and capitalist spatial rationalities. I analyse the sociospatial dimensions of parliamentary enclosure���s technical and legal innovations and compare them to the forms of communal self-regulation of land use customs and everyday regionalisations that preceded it. Through a systematic, replicable mechanism of reterritorialisation, enclosure acts normalised spatial regulations, blurred regional differences in the social organisation of agriculture and erased the modes of autonomous social reproduction linked to common land. Their exercise of dispossession of material resources, social capital and community representations is interpreted therefore as an inaugural logic that would pervade the emergent spatial rationality later known as planning.

Efficiency and spatial equity impacts of high-speed rail extensions in urban areas

Urban areas benefit from significant improvements in accessibility when a new high speed rail (HSR) project is built. These improvements, which are due mainly to a rise in efficiency, produce locational advantagesand increase the attractiveness of these cities, thereby possibly enhancing their competitivenessand economic growth. However, there may be equity issues at stake, as the main accessibility benefits are primarily concentrated in urban areas with a HSR station, whereas other locations obtain only limited benefits. HSR extensions may contribute to an increase in spatial imbalance and lead to more polarized patterns of spatial development. Procedures for assessing the spatial impacts of HSR must therefore follow a twofold approach which addresses issues of both efficiency and equity. This analysis can be made by jointly assessing both the magnitude and distribution of the accessibility improvements deriving from a HSR project. This paper describes an assessment methodology for HSR projects which follows this twofold approach. The procedure uses spatial impact analysis techniques and is based on the computation of accessibility indicators, supported by a Geographical Information System (GIS). Efficiency impacts are assessed in terms of the improvements in accessibility resulting from the HSR project, with a focus on major urban areas; and spatial equity implications are derived from changes in the distribution of accessibility values among these urban agglomerations.

Spatial distribution of the soil carbon pool in a Holm oak dehesa in Spain

Aims Dehesas are agroforestry systems characterized by scattered trees among pastures, crops and/or fallows. A study at a Spanish dehesa has been carried out to estimate the spatial distribution of the soil organic carbon stock and to assess the influence of the tree cover. Methods The soil organic carbon stock was estimated from the five uppermost cm of themineral soil with high spatial resolution at two plots with different grazing intensities. The Universal Kriging technique was used to assess the spatial distribution of the soil organic carbon stocks, using tree coverage within a buffering area as an auxiliary variable. Results A significant positive correlation between tree presence and soil organic carbon stocks up to distances of around 8 m from the trees was found. The tree crown cover within a buffer up to a distance similar to the crown radius around the point absorbed 30 % of the variance in the model for both grazing intensities, but residual variance showed stronger spatial autocorrelation under regular grazing conditions. Conclusions Tree cover increases soil organic carbon stocks, and can be satisfactorily estimated by means of crown parameters. However, other factors are involved in the spatial pattern of the soil organic carbon distribution. Livestock plays an interactive role together with tree presence in soil organic carbon distribution.

Space-time analysis of the urban-rural grafient in the metropolitan area of Madrid and ist surroundings -Guadalajara and Toledo.

According to UN provisions in the period from 2007 to 2050 world population will grow up to 9200 million people. In fact, for the first time in history, in the year 2008 world urban population became higher than rural population. The increase of urban areas and their transport infrastructures has influenced agricultural land use due to their irreversible change, especially when they remain as periurban vacant land, losing their character and identity. In the Europe of the nineties, the traditional urban-rural gradient, characterized by a neat contact between both land types, has become so complex that it has change to a gradient in which it is difficult to separate urban and rural land uses. [Antrop 2004]. A literature review has been made on methodologies used for the urban-rural gradient analysis. One of these methodologies was selected that integrates ecological characterization based on the use of spatial metrics and geographical characterization based on spatial components. Cartographical sources used were Corine Land Cover at 1: 100000 scale and the Spanish Land Use Information System at 1:25000 scale. Urban-rural gradient paradigm is an analysis methodology, coming from landscape ecology, which enables to investigate how urbanization provokes changes in ecological patterns and processes into landscape. [Hahs and McDonnell 2006].The present research adapt this methodology to study the urban-rural gradient in the outskirts of Madrid, Toledo and Guadalajara. Both scales (1:25000 and 1:100000) were simultaneously used to reach the next objectives: 1) Analysis of landscape pattern dynamics in relation to distance to the town centre and major infrastructures. 2) Analysis of landscape pattern dynamics in the fringe of protected areas. The paper presents a new approach to the urban-rural relationship which allows better planning and management of urban ��reas.

Territory and the governmentalisation of social reproduction: parliamentary enclosure and spatial rationalities in the transition from feudalism to capitalism

Recent applications of Foucauldian categories in geography, spatial history and the history of town planning have opened up interesting new perspectives, with respect to both the evolution of spatial knowledge and the genealogy of territorial techniques and their relation to larger socio-political projects, that would be enriched if combined with other discursive traditions. This article proposes to conceptualise English parliamentary enclosureea favourite episode for Marxist historiography, frequently read in a strictly materialist fashioneas a precedent of a new form of sociospatial governmentality, a political technology that inaugurates a strategic manipulation of territory for social change on the threshold between feudal and capitalist spatial rationalities. I analyse the sociospatial dimensions of parliamentary enclosure���s technical and legal innovations and compare them to the forms of communal self-regulation of land use customs and everyday regionalisations that preceded it. Through a systematic, replicable mechanism of reterritorialisation, enclosure acts normalised spatial regulations, blurred regional differences in the social organisation of agriculture and erased the modes of autonomous social reproduction linked to common land. Their exercise of dispossession of material resources, social capital and community representations is interpreted therefore as an inaugural logic that would pervade the emergent spatial rationality later known as planning.

AquaData and AquaGIS: Two computer utilities for temporal and spatial simulations of water-limited yield with AquaCrop.

The crop simulation model AquaCrop, recently developed by FAO can be used for a wide range of purposes. However, in its present form, its use over large areas or for applications that require a large number of simulations runs (e.g., long-term analysis), is not practical without developing software to facilitate such applications. Two tools for managing the inputs and outputs of AquaCrop, named AquaData and AquaGIS, have been developed for this purpose and are presented here. Both software utilities have been programmed in Delphi v. 5 and in addition, AquaGIS requires the Geographic Information System (GIS) programming tool MapObjects. These utilities allow the efficient management of input and output files, along with a GIS module to develop spatial analysis and effect spatial visualization of the results, facilitating knowledge dissemination. A sample of application of the utilities is given here, as an AquaCrop simulation analysis of impact of climate change on wheat yield in Southern Spain, which requires extensive input data preparation and output processing. The use of AquaCrop without the two utilities would have required approximately 1000 h of work, while the utilization of AquaData and AquaGIS reduced that time by more than 99%. Furthermore, the use of GIS, made it possible to perform a spatial analysis of the results, thus providing a new option to extend the use of the AquaCrop model to scales requiring spatial and temporal analyses.