The dynamics of natural populations may be influenced by a variety of factors, ranging from feeding interference and territoriality to the risk of predation and climatic effects. The relative influence of these factors may be contingent upon the quality of the habitat in which individuals reside. A factor that can largely affect population dynamics and that often covaries with habitat structure is predation risk. However, the combined effect of habitat and predation risk can vary according to the social context and intrinsic characteristics that affect individual behavioural responses. This thesis investigates the effects of habitat quality at the level of the population and the individual, and examines how it relates to the above factors in Siberian jays (Perisoreus infaustus), a territorial, group-living species in which the main cause of mortality is predation. The results demonstrate a strong effect of habitat on survival, reproduction and behaviour. Mortality was generally higher in open areas and managed forests and reproductive success decreased after forest management. Breeding females were more sensitive to environmental factors than males, possibly because of higher reproductive costs. Estimates of spatial demography suggested that there were more sinks than sources, and that they were located in open, managed forests. Behavioural decisions confirmed that open forests were associated with higher predation risks. However, decisions depended on social context; immigrants took highest risks and were the recipients of most aggression, largely an effect of social subordination. Also, parents provide their offspring with benefits that are withheld from immigrants. As a result, first-year survival was higher in retained offspring. Investigating the effects of multi-scale habitat quality on individual behaviour and population dynamics has generated an increased understanding of the effects of forest management on the dynamics of this population. This approach should facilitate development of an effective conservation management policy for this species.

In west-central Alberta increased landscape fragmentation has lead to increased human use, having negative effects on wildlife such as the grizzly bear (<i>Ursus arctos</i> L.). Recently, grizzly bears in the Foothills Model Forest were found to select clear cuts of different age ranges as habitat and selected or avoided certain clear cuts depending on the site preparation process employed. Satellite remote sensing offers a practical and cost-effective method by which cut areas, their age, and site preparation activities can be quantified. This thesis examines the utility of spectral reflectance of SPOT-5 pansharpened imagery (2.5m spatial resolution) to identify and map 44 regenerating stands sampled in August 2005. Using object based classification with the Normalized Difference Moisture Index (NDMI), green, and short wave infrared (SWIR) bands, 90% accuracy can be achieved in the detection of forest disturbance. Forest structural parameters were used to calculate the structural complexity index (SCI), the first loading of a principal components analysis. The NDMI, first-order standard deviation and second-order correlation texture measures were better able to explain differences in SCI among the 44 forest stands (R2=0.74). The best window size for the texture measures was 5x5, indicating that this is a measure only detectable at a very high spatial resolution. Age classes of these cut blocks were analysed using linear discriminant analysis and best separated (82.5%) with the SWIR and green spectral bands, second order correlation under a 25x25 window, and the predicted SCI. Site preparation was best classified (90.9%) using the NDMI and homogeneity texture under a 5x5 window. Future applications from this research include the selection of high probability grizzly habitat for high spatial resolution imagery acquisition for detailed mapping initiatives.

In west-central Alberta increased landscape fragmentation has lead to increased human use, having negative effects on wildlife such as the grizzly bear (<i>Ursus arctos</i> L.). Recently, grizzly bears in the Foothills Model Forest were found to select clear cuts of different age ranges as habitat and selected or avoided certain clear cuts depending on the site preparation process employed. Satellite remote sensing offers a practical and cost-effective method by which cut areas, their age, and site preparation activities can be quantified. This thesis examines the utility of spectral reflectance of SPOT-5 pansharpened imagery (2.5m spatial resolution) to identify and map 44 regenerating stands sampled in August 2005. Using object based classification with the Normalized Difference Moisture Index (NDMI), green, and short wave infrared (SWIR) bands, 90% accuracy can be achieved in the detection of forest disturbance. Forest structural parameters were used to calculate the structural complexity index (SCI), the first loading of a principal components analysis. The NDMI, first-order standard deviation and second-order correlation texture measures were better able to explain differences in SCI among the 44 forest stands (R2=0.74). The best window size for the texture measures was 5x5, indicating that this is a measure only detectable at a very high spatial resolution. Age classes of these cut blocks were analysed using linear discriminant analysis and best separated (82.5%) with the SWIR and green spectral bands, second order correlation under a 25x25 window, and the predicted SCI. Site preparation was best classified (90.9%) using the NDMI and homogeneity texture under a 5x5 window. Future applications from this research include the selection of high probability grizzly habitat for high spatial resolution imagery acquisition for detailed mapping initiatives.

Current forest management in boreal northeastern Ontario results in young, even-aged forests; however, fire history research has found old stands with multiple cohorts of trees are common, supporting the value of Multi-cohort Management. I investigated relationships between insect communities and stand live-tree diameter distribution, cohort class and structure. Results showed that variation in abundances of Carabidae, Diapriidae, Diptera and Hymenoptera were not strongly predicted by cohort class. The concept showed greater strength when parameters of live-tree diameter distributions were used. Forest structure, not age, was important for all communities, including heterogeneity of understory and/or overstory vegetation. Trap height was a strong predictor of aerial insect community structure, with insect abundance higher in the understory than in the canopy. In summary, a more diversified classification approach which includes important habitat features in addition to simple characterization of diameter distributions should be considered to better assess forest structural variation and management.

Current forest management in boreal northeastern Ontario results in young, even-aged forests; however, fire history research has found old stands with multiple cohorts of trees are common, supporting the value of Multi-cohort Management. I investigated relationships between insect communities and stand live-tree diameter distribution, cohort class and structure. Results showed that variation in abundances of Carabidae, Diapriidae, Diptera and Hymenoptera were not strongly predicted by cohort class. The concept showed greater strength when parameters of live-tree diameter distributions were used. Forest structure, not age, was important for all communities, including heterogeneity of understory and/or overstory vegetation. Trap height was a strong predictor of aerial insect community structure, with insect abundance higher in the understory than in the canopy. In summary, a more diversified classification approach which includes important habitat features in addition to simple characterization of diameter distributions should be considered to better assess forest structural variation and management.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As florestas tropicais amazônicas são um importante reservatório de carbono acima e abaixo do solo. Elas desempenham uma importante função tanto no sequestro do carbono atmosférico quanto no armazenamento desse carbono em forma de biomassa. O objetivo desse trabalho foi quantificar a variação espacial da biomassa arbórea viva e avaliar o efeito de variáveis climáticas e ambientais ao longo de cerca de 400 km de florestas alagadas no médio e baixo rio Branco. Especificamente, foi avaliado o efeito (i) da duração da inundação, (ii) do comprimento da estação seca e (iii) da textura e fertilidade do solo no estoque de biomassa acima do solo. Foram amostrados 2.432 indivíduos com Diâmetro à altura do Peito (DAP) &#8805; 10 cm, distribuídos em 54 parcelas compridas (250 metros) e estreitas (4 metros) de 0,1 ha. Para cada indivíduo amostrado, além do DAP, foram determinadas a altura total e a densidade da madeira. A biomassa viva acima do solo das árvores foi estimada através da média de três modelos alométricos que consideram DAP, densidade da madeira e altura das árvores. A biomassa de palmeiras foi estimada com base em um único modelo que considera apenas a altura dos indivíduos. A biomassa variou de 21,5 a 245,15 Mg/ha. Não foi observada relação entre a biomassa e as variáveis climáticas (precipitação média anual e comprimento da estação seca). As variáveis ambientais: solo (% de argila) e a duração da inundação também não explicaram a variação da biomassa arbórea viva acima do solo nas florestas alagadas do rio Branco. Estes resultados representam as primeiras estimativas de biomassa arbórea para as florestas alagadas do rio Branco. A grande variação observada entre as parcelas sugere que eventos estocásticos locais, a estrutura da floresta e a composição florística podem ser mais importantes para explicar a variação da biomassa do que fatores climáticos e características do solo. / Amazonian forests are an important above and belowground carbon reservoir. They play an important role in both the sequestration of atmospheric carbon and storage of carbon as biomass. The aim of this study was to quantify the spatial variation of above ground tree live biomass and evaluate the effects of climatic and environmental predictors along ~400km of flooded forests in the middle and lower rio Branco (Roraima). Specifically, I related plot-based biomass estimates with (i) duration of flooding, (ii) length of the dry season, and (iii) texture and fertility of the soil. A total of 2.432 individuals with diameter at breast height (DBH) &#8805; 10 cm where sampled in 54 long (250 meters) and narrow (4 meters) plots of 0.1 hectare. For each individual sampled, were also determined: total tree height and wood density. The above ground live biomass of trees was estimated by the average of three allometric models that consider DBH, wood density, and tree height. Palm biomass was estimated based on a single model that considers only the height of individuals. Biomass estimates presented a 10-fold variation, ranging from 21.5 to 245.15 Mg/ha. No relationship between biomass and climatic variables (mean annual rainfall and length of dry season) were observed. Environmental variables: soil (% clay) and the duration of the flood also did not explain the variation in tree biomass in the flooded forests of the rio Branco. These represent the first tree biomass estimates for the flooded forests of the rio Branco, and the large biomass variation observed in the plots suggest that local stochastic events, forest structure and floristic composition may be more important in explaining biomass variation than climatic and soil factors.

La thèse s'inscrit dans l'étude de la structuration des forêts à partir des propriétés de la canopée telles que décrites par la distribution spatiale ou la taille des houppiers des arbres dominants. L'approche suivie est fondée sur la théorie des Processus Ponctuels Marqués (PPM) qui permet de modéliser ces houppiers comme des disques sur images considérées comme un espace 2D. Le travail a consisté à évaluer le potentiel des PPM pour détecter automatiquement les houppiers d'arbres dans des images optiques de très résolution spatiale acquises sur des forêts de mangroves et des plantations d'Eucalyptus. Pour les mangroves, nous avons également travaillé sur des images simulées de réflectance et des données Lidar. Différentes adaptations (paramétrage, modèles d'énergie) de la méthode de PPM ont été testées et comparées grâce à des indices quantitatifs de comparaison entre résultats de la détection et références de positionnement issues du terrain, de photo-interprétation ou de maquettes forestières.Dans le cas des mangroves, les tailles de houppier estimées par détection restent cohérentes avec les sorties des modèles allométriques disponibles. Les résultats thématiques indiquent que la détection par PPM permet de cartographier dans une jeune plantation d'Eucalyptus la densité locale d'arbres dont la taille des houppiers est proche de la résolution spatiale de l'image (0.5m). Cependant, la qualité de la détection diminue quand le couvert se complexifie. Ce travail dresse plusieurs pistes de recherche tant mathématique, comme la prise en compte des objets de forme complexe, que thématiques, comme l'apport des informations forestières à des échelles pertinentes pour la mise au point de méthodes de télédétection. / This PhD work aims at providing information on the forest structure through the analysis of canopy properties as described by the spatial distribution and the crown size of dominant trees. Our approach is based on the Marked Point Processes (MPP) theory, which allows modeling tree crowns observed in remote sensing images by discs belonging a two dimensional space. The potential of MPP to detect the trees crowns automatically is evaluated by using very high spatial resolution optical satellite images of both Eucalyptus plantations and mangrove forest. Lidar and simulated reflectance images are also analyzed for the mangrove application. Different adaptations (parameter settings, energy models) of the MPP method are tested and compared through the development of quantitative indices that allow comparison between detection results and tree references derived from the field, photo-interpretation or the forest mockups.In the case of mangroves, the estimated crown sizes from detections are consistent with the outputs from the available allometric models. Other results indicate that tree detection by MPP allows mapping, the local density of trees of young Eucalyptus plantations even if crown size is close to the image spatial resolution (0.5m). However, the quality of detection by MPP decreases with canopy closeness. To improve the results, further work may involve MPP detection using objects with finer shapes and forest data measurements collected at the tree plant scale.

A importância das matas ciliares para a manutenção de diversas funções ecológicas e hidrológicas, reconhecida a ponto de tais formações receberem proteção legal específica, não impediu que estas fossem destruídas indiscriminadamente durante o processo de ocupação do território brasileiro. Estima-se que, só no Estado de São Paulo, cerca de 600 mil hectares de áreas marginais aos corpos d\'água encontram-se ocupados com outros usos que não a vegetação natural, necessitando, portanto, de ações de recuperação. Embora exista um número significativo de trabalhos de revegetação de áreas degradadas, principalmente em matas ciliares, poucos são os resultados de pesquisas sobre o desenvolvimento a longo-prazo de plantios de recomposição de mata ciliar. Nem os plantios mais antigos, aleatórios, e nem os mais recentes, baseados nos processos sucessionais, têm sido submetidos a análises que possibilitem avaliar a eficácia destes métodos de plantio na restauração da mata ciliar com sua forma e funções originais. O objetivo geral desta pesquisa foi o de avaliar a auto-sustentabilidade e as tendências sucessionais de uma mata ciliar implantada, com base em aspectos da estrutura e funcionamento da floresta em trechos de diferentes idades. Neste sentido avaliou-se a floresta existente atualmente, do ponto de vista da composição e estrutura da comunidade; caracterizou-se e quantificou-se o estrato regenerativo da floresta, visando compreender os processos de regeneração natural;caracterizou-se a sazonalidade da queda de folhedo através de sua quantificação periódica e sua contribuição para o retorno de nutrientes ao solo; caracterizou-se o solo sob a floresta, e comparou-se os resultados com área não reflorestada; comparou-se a floresta implantada com florestas naturais através dos parâmetros analisados: riqueza e diversidade florística do estrato arbóreo, densidade absoluta, densidade relativa, área basal, estratificação da floresta, similaridade florística, cobertura das copas, regeneração natural, características químicas do solo e produção e conteúdo de nutrientes no folhedo. Analisando-se as áreas reflorestadas como um todo, constata-se a existência de uma mata ciliar exuberante e fisionomicamente bem estruturada, cujo papel de proteção aos recursos hídricos e ao solo tem sido desempenhado de forma evidente. Alguns resultados obtidos são de extrema importância: no setor de 28 anos, 69% das árvores amostradas surgiram espontaneamente e apenas 31% são indivíduos plantados, demonstrando que está havendo um aumento natural da riqueza florística, o que prova que a natureza encarrega-se de perpetuar a floresta fazendo os \"ajustes\" necessários. Processos ecológicos como a dispersão de sementes e a regeneração natural estão incorporados na dinâmica florestal do local, podendo-se afirmar que a auto-sustentabilidade florestal da comunidade que se formou a partir do plantio de mata ciliar já está garantida. A hipótese deste trabalho foi confirmada pelos resultados obtidos: com o decorrer do tempo a mata ciliar implantada tende a se tornar cada vez mais semelhante à mata ciliar natural, em estrutura e função. / The importance of riparian forests to maintain the many hydrologic and ecological functions, acknowledged to the point of receiving specific legal protection, did not prevent their indiscriminate destruction during the process of land settlement in Brazil. It is estimated that in São paulo state alone about 600 thousands hectares of stream-side areas have been occupied by other uses rather than natural vegetation, therefore, requiring actions of restoration. Although there is a significant number of studies in restoration of degraded areas mainly in riparian forests, the results in research on development of restoration planting of riparian forests in the long term are few. Neither older random plantings nor more recent ones based on sucession processes have been subjected to analysis that would make it possible to evaluate the efficacy of these methods of planting for restoration of riparian forest with its original form and functions. The general aim of this study was to evaluate self-sustainability and sucession tendencies of a planted riparian forest, based on aspects of structure and functioning of the forest in patches of different ages. Thus, the current existing forest was evaluated regarding composition and structure of the community; the regenerative stratum of the forest was characterized and quantified with the purpose of understanding natural regeneration processes; the seasonability of fall foliage through its periodic quantification and itscontribution to the return of nutrients to the soil was characterized; the soil underneath the forest was characterized, and the results in areas that were not restored were compared; planted forests and natural forests were compared through parameters analyzed: richness and floristic diversity of the tree stratum, absolute density, relative density, basal area, forest stratification, floristic similarity, canopy cover, natural regeneration, chemical characteristics of the soil and production and nutrients content in the foliage. By analyzing restored areas as a whole, we can confirm an exuberant and physiognomically well structured riparian forest, whose role of protecting hydric resources and the soil has been easily noticed. Some ecological indicators assessed such as the abundant natural regeneration existing under the planted forest and the spontaneous development of new species show that there has been a natural increase in floristic richness, which proves that nature manages to perpetuate forests by making the necessary adjustments. The hypothesis of this work was confirmed by the results obtained: with time the planted forest tends to become more and more similar to the natural forest, both in structure and function.

<p>  </p> <p>In recent decades, wildlife studies have begun to incorporate more structural characteristics into studies of habitat. However, most still collect habitat data primarily from field measurements, which are limited in spatial extent and force researchers to extrapolate from small-scale, ground-based measures. LiDAR offers the opportunity to objectively measure habitat features across landscape-level extents. I mapped and measured forest canopy structural diversity at 181 plots across Indiana at a series of three (25-m, 50-m, and 100-m) radii to quantify landscape heterogeneity across space, utilizing new 2016–2020 aerial LiDAR in tandem with high-resolution camera traps. I aimed to quantify the relationship between use of forest sites by seven wildlife species and habitat structural characteristics, specifically predicting species occupancy as a function of LiDAR-derived metrics. I predicted that habitat generalists like raccoons (<em>Procyon lotor</em>) and Virginia opossum (<em>Didelphis virginiana</em>) would be best predicted by the null hypothesis and that measures of gap fraction would best predict edge species such as coyote (<em>Canis latrans</em>), white-tailed deer (<em>Odocoileus virginianus</em>), and wild turkey (<em>Meleagris gallopavo</em>). Additionally, I predicted a positive relationship between vegetation area and both eastern cottontail rabbit (<em>Sylvilagus floridanus</em>) and tree squirrels (Sciuridae spp.). I expected that measures of habitat heterogeneity would be included in best models for tree squirrels and white-tailed deer, and that models for squirrels would have lower root mean square error (RMSE) values. Ultimately, structural metrics varied across radii, and best models depended on plot radius size. Measures of vertical heterogeneity were the best predictors for species like raccoon, wild turkey, and coyote, with a higher probability of occupancy for all three with increased heterogeneity. Additionally, models for eastern cottontail rabbit incorporating vegetation area indices, Gini diversity, and gap fraction demonstrated significance and low predictive error. Habitat generalists, such as white-tailed deer and Virginia opossum did not select for specific structural metrics and were best predicted by the null model. Ultimately, these results indicated that LiDAR is a promising potential tool for measuring ecologically meaningful variables at scales large enough to properly represent home range and resource use at the home-range level, filling an important gap in our understanding. </p>

<p>Forest canopies are a critical component of forest ecosystems as they influence many important functions. Specifically, the structure of forest canopies is a driver of the magnitude and rate of these functions. Therefore, being able to accurately measure canopy structure is crucial to ensure ecological models and forest management plans are as robust and efficient as possible. However, canopies are complex and dynamic entities and thus their structure can be challenging to accurately measure. Here we study the feasibility of using lidar to measure forest canopy structure across large spatial extents by investigating the compatibility of aerial and terrestrial lidar systems. Building on known structure-function relationships measured with terrestrial lidar, we establish grounds for scaling these relationships to the aerial scale. This would enable accurate measures of canopy structural complexity to be acquired at landscape and regional scales without the time and labor requirements of terrestrial data collection. Our results illustrate the potential for measures of canopy height, vegetation area, horizontal cover, and canopy roughness to be upscaled. Furthermore, we highlight the benefit of utilizing multivariate measures of canopy structure, and the capacity of lidar to identify forest structural types. Moving forward, lidar is a tool to be utilized in tandem with other technologies to best understand the spatial and temporal dynamics of forests and the influence of physical ecosystem structure. </p>