Academic literature on the topic 'Tree Population dynamic'
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Journal articles on the topic "Tree Population dynamic"
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Isaacson, S., S. Rachmilevitch, J. E. Ephrath, S. Maman, and D. G. Blumberg. "MONITORING TREE POPULATION DYNAMICS IN ARID ZONE THROUGH MULTIPLE TEMPORAL SCALES: INTEGRATION OF SPATIAL ANALYSIS, CHANGE DETECTION AND FIELD LONG TERM MONITORING." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B7 (June 21, 2016): 513–15. http://dx.doi.org/10.5194/isprs-archives-xli-b7-513-2016.
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High mortality rates and lack of recruitment in the acacia populations throughout the Negev Desert and the Arava rift valley of Israel have been reported in previous studies. However, it is difficult to determine whether these reports can be evidence to a significant decline trend of the trees populations. This is because of the slow dynamic processes of acaia tree populations and the lack of long term continuous monitoring data. We suggest a new data analysis technique that expands the time scope of the field long term monitoring of trees in arid environments. This will enables us to improve our understanding of the spatial and temporal changes of these populations. <br><br> We implemented two different approaches in order to expand the time scope of the acacia population field survey: (1) individual based tree change detection using Corona satellite images and (2) spatial analysis of trees population, converting spatial data into temporal data. The next step was to integrate the results of the two analysis techniques (change detection and spatial analysis) with field monitoring. This technique can be implemented to other tree populations in arid environments to help assess the vegetation conditions and dynamics of those ecosystems.
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Isaacson, S., S. Rachmilevitch, J. E. Ephrath, S. Maman, and D. G. Blumberg. "MONITORING TREE POPULATION DYNAMICS IN ARID ZONE THROUGH MULTIPLE TEMPORAL SCALES: INTEGRATION OF SPATIAL ANALYSIS, CHANGE DETECTION AND FIELD LONG TERM MONITORING." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B7 (June 21, 2016): 513–15. http://dx.doi.org/10.5194/isprsarchives-xli-b7-513-2016.
Full textAbstract:
High mortality rates and lack of recruitment in the acacia populations throughout the Negev Desert and the Arava rift valley of Israel have been reported in previous studies. However, it is difficult to determine whether these reports can be evidence to a significant decline trend of the trees populations. This is because of the slow dynamic processes of acaia tree populations and the lack of long term continuous monitoring data. We suggest a new data analysis technique that expands the time scope of the field long term monitoring of trees in arid environments. This will enables us to improve our understanding of the spatial and temporal changes of these populations. <br><br> We implemented two different approaches in order to expand the time scope of the acacia population field survey: (1) individual based tree change detection using Corona satellite images and (2) spatial analysis of trees population, converting spatial data into temporal data. The next step was to integrate the results of the two analysis techniques (change detection and spatial analysis) with field monitoring. This technique can be implemented to other tree populations in arid environments to help assess the vegetation conditions and dynamics of those ecosystems.
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Beloiu, Mirela, and Carl Beierkuhnlein. "Differences in the Spatial Structure of Two Pinus cembra L. Populations in the Carpathian Mountains." Forests 10, no. 4 (April 11, 2019): 326. http://dx.doi.org/10.3390/f10040326.
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Pinus cembra L. is a key species of high elevation forest ecosystems in Europe. However, in most mountain ranges, its importance has declined considerably. Remnant populations are often isolated and their dynamics and functioning are not well understood. Here, we apply novel approaches in pattern analysis to two P. cembra populations in the Carpathian Mountains in order to identify commonalities and divergences in their spatial structure and dynamics. Four study sites (1.2 ha each) were investigated within the treeline ecotone in two protected areas that differ in terms of protection status. Based on height and diameter, the individuals were classified into three size-classes: sapling, intermediate and adult trees. Spatial distribution and interactions between tree sizes were analyzed using point pattern analysis. The overall structure of all trees was aggregated at a small distance and regular at a greater distance in the population from the Natura 2000 site (p = 0.002), while in the National Park population it was a random pattern. However, the general patterns do not apply to tree size classes and the relationship among them. In the Natura 2000 site, there was no correlation, all the trees were mixed, regardless of their size. In the National Park, the sapling and intermediate were strongly clustered (p = 0.001), but the adult trees were spatially separated from all juveniles, forming patches at a lower elevation. In both areas, spatial patterns indicate the dynamics of the P. cembra population. Whereas in the National Park population, there is evidence of an upward shift, which cannot be confirmed in Natura 2000, where size classes are completely mixed and the dynamic does not translate into an expansion of the population area. The spatial differences between the two populations indicate that conservation strategies need to be developed more individually to support the regeneration of these isolated populations.
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Möller, Simon, Louis du Plessis, and Tanja Stadler. "Impact of the tree prior on estimating clock rates during epidemic outbreaks." Proceedings of the National Academy of Sciences 115, no. 16 (April 2, 2018): 4200–4205. http://dx.doi.org/10.1073/pnas.1713314115.
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Bayesian phylogenetics aims at estimating phylogenetic trees together with evolutionary and population dynamic parameters based on genetic sequences. It has been noted that the clock rate, one of the evolutionary parameters, decreases with an increase in the sampling period of sequences. In particular, clock rates of epidemic outbreaks are often estimated to be higher compared with the long-term clock rate. Purifying selection has been suggested as a biological factor that contributes to this phenomenon, since it purges slightly deleterious mutations from a population over time. However, other factors such as methodological biases may also play a role and make a biological interpretation of results difficult. In this paper, we identify methodological biases originating from the choice of tree prior, that is, the model specifying epidemiological dynamics. With a simulation study we demonstrate that a misspecification of the tree prior can upwardly bias the inferred clock rate and that the interplay of the different models involved in the inference can be complex and nonintuitive. We also show that the choice of tree prior can influence the inference of clock rate on real-world Ebola virus (EBOV) datasets. While commonly used tree priors result in very high clock-rate estimates for sequences from the initial phase of the epidemic in Sierra Leone, tree priors allowing for population structure lead to estimates agreeing with the long-term rate for EBOV.
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Needham, Jessica, Cory Merow, Chia-Hao Chang-Yang, Hal Caswell, and Sean M. McMahon. "Inferring forest fate from demographic data: from vital rates to population dynamic models." Proceedings of the Royal Society B: Biological Sciences 285, no. 1874 (March 7, 2018): 20172050. http://dx.doi.org/10.1098/rspb.2017.2050.
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As population-level patterns of interest in forests emerge from individual vital rates, modelling forest dynamics requires making the link between the scales at which data are collected (individual stems) and the scales at which questions are asked (e.g. populations and communities). Structured population models (e.g. integral projection models (IPMs)) are useful tools for linking vital rates to population dynamics. However, the application of such models to forest trees remains challenging owing to features of tree life cycles, such as slow growth, long lifespan and lack of data on crucial ontogenic stages. We developed a survival model that accounts for size-dependent mortality and a growth model that characterizes individual heterogeneity. We integrated vital rate models into two types of population model; an analytically tractable form of IPM and an individual-based model (IBM) that is applied with stochastic simulations. We calculated longevities, passage times to, and occupancy time in, different life cycle stages, important metrics for understanding how demographic rates translate into patterns of forest turnover and carbon residence times. Here, we illustrate the methods for three tropical forest species with varying life-forms. Population dynamics from IPMs and IBMs matched a 34 year time series of data (albeit a snapshot of the life cycle for canopy trees) and highlight differences in life-history strategies between species. Specifically, the greater variation in growth rates within the two canopy species suggests an ability to respond to available resources, which in turn manifests as faster passage times and greater occupancy times in larger size classes. The framework presented here offers a novel and accessible approach to modelling the population dynamics of forest trees.
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Shen, Yong, Louis S. Santiago, Lei Ma, Guo-Jun Lin, Ju-Yu Lian, Hong-Lin Cao, and Wan-Hui Ye. "Forest dynamics of a subtropical monsoon forest in Dinghushan, China: recruitment, mortality and the pace of community change." Journal of Tropical Ecology 29, no. 2 (February 18, 2013): 131–45. http://dx.doi.org/10.1017/s0266467413000059.
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Abstract:Structure and demographics in many tropical forests is changing, but the causes of these changes remain unclear. We studied 5 y (2005–2010) of species turnover, recruitment, mortality and population change data from a 20-ha subtropical forest plot in Dinghushan, China, to identify trends in forest change, and to test whether tree mortality is associated with intraspecific or interspecific competition. We found the Dinghushan forest to be more dynamic than one temperate and two tropical forests in a comparison of large, long-term forest dynamics plots. Within Dinghushan, size-class distributions were bell-shaped only for the three most dominant species and reverse J-shaped for other species. Bell-shaped population distributions can indicate a population in decline, but our data suggest that these large and long-lived species are not in decline because the pattern is driven by increasing probabilities of transition to larger size class with increasing size and fast growth in saplings. Spatially aggregated tree species distributions were common for surviving and dead individuals. Competitive associations were more frequently intraspecific than interspecific. The competition that induced tree mortality was more associated with intraspecific than interspecific interactions. Intraspecific competitive exclusion and density-dependence appear to play important roles in tree mortality in this subtropical forest.
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Scire, Jérémie, Joëlle Barido-Sottani, Denise Kühnert, Timothy G. Vaughan, and Tanja Stadler. "Robust Phylodynamic Analysis of Genetic Sequencing Data from Structured Populations." Viruses 14, no. 8 (July 27, 2022): 1648. http://dx.doi.org/10.3390/v14081648.
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The multi-type birth–death model with sampling is a phylodynamic model which enables the quantification of past population dynamics in structured populations based on phylogenetic trees. The BEAST 2 package bdmm implements an algorithm for numerically computing the probability density of a phylogenetic tree given the population dynamic parameters under this model. In the initial release of bdmm, analyses were computationally limited to trees consisting of up to approximately 250 genetic samples. We implemented important algorithmic changes to bdmm which dramatically increased the number of genetic samples that could be analyzed and which improved the numerical robustness and efficiency of the calculations. Including more samples led to the improved precision of parameter estimates, particularly for structured models with a high number of inferred parameters. Furthermore, we report on several model extensions to bdmm, inspired by properties common to empirical datasets. We applied this improved algorithm to two partly overlapping datasets of the Influenza A virus HA sequences sampled around the world—one with 500 samples and the other with only 175—for comparison. We report and compare the global migration patterns and seasonal dynamics inferred from each dataset. In this way, we show the information that is gained by analyzing the bigger dataset, which became possible with the presented algorithmic changes to bdmm. In summary, bdmm allows for the robust, faster, and more general phylodynamic inference of larger datasets.
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Widyati, E., M. Siarudin, and Y. Yonky Indrajaya. "The Dynamic of Functional Microbes Community Under Auri (Acacia auriculiformis Cunn. Ex Benth) Agroforestry System." Jurnal Manajemen Hutan Tropika (Journal of Tropical Forest Management) 28, no. 2 (August 9, 2022): 119–27. http://dx.doi.org/10.7226/jtfm.28.2.119.
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Microbes are important rhizosphere constituents for providing nutrients in the soil. This study analyzes the dynamic of soil functional microbes' populations on land managed as an agroforestry (AF) system. The AF system consists of a 2-years old auri tree combined with several crops, i.e., wild grasses, peanuts (Arachis hypogaea), pigeon pea (Cajanus cajan), and maize (Zea mays). Soil samples were collected from each rhizosphere and then analyzed for their chemical properties such as N, P, K, pH, and C organic contents. The population of functional microbes was observed by isolation of the non-symbiotic N-fixer microbes (BNF), the cellulose-degrading microbes (CDM), and the phosphate solubilizing microbes (PSM) in their selective media. The total soil sugars were also tested for root exudates. The results showed that in an auri agroforestry system, the kind of crops determines the content of the soil organic material that is turned-offer into the soil. This affects the population structure and functional microbial abundance in the rhizosphere. Furthermore, microbial colonization in the rhizosphere affects plants in producing root exudates. Then, root exudates shape the structures of the microbial community, as well as an influence among inhabitants in defining mineralization of soil organic matter, nutrient availability, and trees performance.
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Woziwoda, Beata, Katarzyna Pawicka, and Grzegorz J. Wolski. "Charakterystyka lasu grądowego z jodłą w rezerwacie „Jamno”." Biuletyn Szadkowski 12 (December 30, 2012): 127–43. http://dx.doi.org/10.18778/1643-0700.12.07.
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The “Jamno” nature reserve was established to protect the forest community with European silver fir Abies alba Mill. on the northern border of natural occurrence of this tree species in Poland. The results of current phytosociological studies (done in 2011) show that the oak-hornbeam forest – “Tilio-Carpinetum calamagrostietosum” association with “Abies alba”, exist within reserve. The present structure and species composition of studied community is determined by spontaneous changes of tree stand. The different proportion of silver fir in shrub and tree stand layers indicate the dynamic changes within this species population.
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Sinsin, Tudal E. M., Fouad Mounir, and Ahmed El Aboudi. "Conservation, valuation and sustainable development issues of the Argan Tree Biosphere Reserve in Morocco." Environmental & Socio-economic Studies 8, no. 1 (March 1, 2020): 28–35. http://dx.doi.org/10.2478/environ-2020-0004.
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AbstractThe argan tree is a multi-purpose tree (fruit tree, medicinal, cosmetic, and pastoral plant) found in the semi-arid and arid regions of North Africa. It is under strong human pressure such as the impact of population growth, crop expansion, overgrazing, and wood and fruit exploitation that are also the main causes of desertification in the rest of the world. Over the years, interest in this beneficial tree and demand for its products have increased: especially with the increase in the price of argan oil, which is now one of the most expensive and much in demand oils in the world. This increase has led to many socio-political, economic and cultural changes at the national, regional and local levels, especially in farming behaviour and the habits of the local population. This bibliographic research was therefore conducted in order to analyse the various changes and their consequences on the planning, conservation, and management methods implemented in the argan tree area and their effects on the habits of the local population in order to ensure the sustainability of the Argan Tree Biosphere Reserve in Morocco. Indeed, the aims of this study were, firstly, to analyse the change dynamic of argan forest area in the ABR; and secondly, to investigate the impact of various socio-political, economic and cultural changes resulting from increased prices of argan oil on planning, conservation, and management methods of argan tree ecosystem and on the habits of the local population.
Dissertations / Theses on the topic "Tree Population dynamic"
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Villari, Caterina. "Fungi associated with the pine engraver beetle Ips acuminatus and their interactions with the host tree." Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3422532.
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Conifer bark beetles are typically associated with complexes of fungi with which they can display different functional relationships. Some of the fungi, generally non phytopathogenic, are known to have a directly mutualistic interaction with the beetles, serving as nourishment to the larvae. Other associated fungi are thought to be involved in the process of exhausting plant defenses, which is a necessary step for the insects to overcome host tree resistance and colonize the plant. In the latter case, bark beetle-associated fungi are often tree pathogenic species belonging to the morphologically homogenous group of the ophiostomatoid fungi, also referred to as ‘blue-stain’ fungi. In spite of the great interest the bark beetle-fungi symbiosis has gained in time, many fundamental aspects of this relationship are still widely debated, as for instance the degree of dependence of bark beetles on the blue-stain fungi in order to succeed their establishment in the host plant.
In this thesis I addressed the fungal community associated with the pine engraver beetle Ips acuminatus (Gyll.), a small bark beetle infesting thin bark of Scots pine (Pinus sylvestris L.) and that has been recently reported as pest in many alpine forests. I. acuminatus associated fungal community includes the obligate nutritional fungus Hyalorhinocladiella macrospora (Franke-Grosm.) Harr. and a specific blue-stain fungus which is consistently associated with the vector, but which identity is still uncertain. Early reports describe it as Ophiostoma clavatum Math.-Käärik, while a later research reported O. brunneo-ciliatum Math. instead. Objectives of the thesis were to determine the identity of the blue-stain fungi associated with I. acuminatus, and to investigate the fungal community interactions with the host plant, in order to better define the functional relationships occurring between the bark beetle and the associated fungi, and therefore contribute to the attempts in understanding ecology and population dynamics of this damaging species.
In the first work a blue-stain fungus associated with I. acuminatus specimens collected in Italy and Sweden was isolated and identified. The identification of the species was achieved with both the support of morphological methods and DNA sequence-based methods, and the species resulted to be O. clavatum, in agreement with the first researches focused on I. acuminatus associated fungi.
In the second work, to clearly assess which of the previously described Ophiostoma species was the main blue-stain fungus associated with the pine engraver beetle, three loop-mediated isothermal amplification (LAMP) assays were developed and employed in a survey which has covered six Italian populations of I. acuminatus. The results confirmed that the identity of the blue-stain fungus more consistently associated with I. acuminatus in the Italian Alps is O. clavatum, while O. brunneo-ciliatum was not detected in any of the samples. Results of this study showed also that the occurrence of O. clavatum varies accordingly to the population dynamic phase of the vector, and is slightly lower in the outbreak populations.
In the third work, the local and systemic defense responses of Scots pine against both the nutritional and the blue-stain fungi were characterized by identifying and quantifying terpenoids, phenolic compounds, and lignin. Results indicated that Scots pine has a generic, rather than specific, induced response. The fact that the nutritional and the blue-stain fungi triggered comparable induced defense responses suggests that even a non-pathogenic fungus may participate in exhausting host plant defenses, indirectly assisting in the beetle establishment process. This finding contributes to the further development of current theories on the role of associated fungal complexes in bark beetle ecology.
In the last work, correlation patterns within constitutive defense secondary metabolites of Scots pine and potential trade-offs between constitutive concentration and inducible variation of individual chemical compounds were tested. Results revealed that different compounds display different behaviors, but no overall negative associations between defensive traits were found.
On the whole, the four contributions of this thesis provide suggestions for a revaluation of one of the current theories on the role of associated fungi in bark beetles host establishment, and hints to understand the role of associated fungi in the population dynamics of bark beetles. Moreover, they clarify some aspects of Scots pine defense mechanisms, highlighting its competitiveness.Gli scolitidi delle conifere sono insetti spesso associati ad un complesso di funghi con i quali possono instaurare differenti interazioni ecologiche. Alcuni di questi funghi, generalmente non fitopatogeni, sono coinvolti in un’interazione mutualistica diretta e vengono utilizzati come nutrimento per le larve del vettore. Altri funghi associati, invece, sono ritenuti coinvolti nel processo di esaurimento delle difese della pianta, che per l’insetto è uno dei passaggi necessari per superare la resistenza dell’ospite e poterlo quindi colonizzare. In quest’ultimo caso, i funghi associati sono di norma specie patogene appartenenti al gruppo morfologico dei funghi ophiostomatoidi, noti anche come ‘funghi di azzurramento’. Nonostante l’interesse che la simbiosi tra scolitidi e funghi ha riscosso nel tempo, molti degli aspetti fondamentali di questa interazione sono ancora discussi, come ad esempio il grado di dipendenza degli insetti vettori dai loro simbionti nelle fasi di colonizzazione della pianta ospite. In questa tesi è stata presa in considerazione la comunità fungina associata a Ips acuminatus (Gyll.), un piccolo scolitide che attacca di preferenza le parti del tronco del pino silvestre (Pinus sylvestris L.) con corteccia sottile, e che di recente ha causato numerose infestazioni in varie zone distribuite sull’arco alpino. Una delle specie che fanno parte della comunità fungina associata ad I. acuminatus è il simbionte alimentare Hyalorhinocladiella macrospora (Franke-Grosm.) Harr. Fa inoltre parte del complesso anche uno specifico fungo di azzurramento costantemente associato al vettore, ma la cui identità non è ancora ben definita. Le prime segnalazioni lo descrivono come Ophiostoma clavatum Math.-Käärik, mentre ricerche successive riportano O. brunneo-ciliatum Math. Gli obiettivi che questa tesi si è prefissa sono stati determinare l’effettiva identità del fungo di azzurramento associato ad I. acuminatus, ed indagare le interazioni del complesso fungino con la pianta ospite, al fine di definire meglio le relazioni che intercorrono tra scolitidi e fungi associati, e poter quindi contribuire ai tentativi di chiarire l’ecologia e la dinamica di popolazione di questo insetto dannoso. Nel primo lavoro sono stati descritti l’isolamento e l’identificazione di una specie fungina isolata da individui di I. acuminatus raccolti in Italia e in Svezia. L’identificazione della specie è avvenuta sia grazie all’osservazione delle caratteristiche morfologiche sia mediante un approccio di tipo molecolare. La specie è risultata essere O. clavatum, come era stato indicato nelle prime segnalazioni riguardanti i funghi associati ad I. acuminatus. Nel secondo lavoro sono stati descritti la messa punto e l’utilizzo di tre sonde molecolari per loop-mediated isothermal amplification (LAMP), con l’obiettivo di determinare quale delle due specie del genere Ophiostoma sopracitate fosse effettivamente il fungo maggiormente associato a I. acuminatus nell’arco alpino. I risultati, riguardanti sei popolazioni italiane dell’insetto, hanno confermato che la specie maggiormente presente è O. clavatum, mentre O. brunneo-ciliatum non è mai stata rilevata. I risultati di questo studio hanno mostrato anche che la frequenza di associazione di I. acuminatus con O. clavatum varia a seconda della fase epidemica, ed è minore nei nuclei di infestazione rispetto alle popolazioni endemiche. Nel terzo lavoro sono state caratterizzate le risposte sia locali sia sistemiche del pino silvestre alla colonizzazione da parte del simbionte alimentare e del fungo di azzurramento, identificando e quantificando alcuni metaboliti secondari, come terpeni, fenoli e lignina. I risultati hanno mostrato che il pino silvestre risponde in maniera generica anziché specifica all’induzione. Il fatto inoltre che il simbionte alimentare e il fungo di azzurramento abbiano stimolato una risposta simile di loro suggerisce che anche un fungo non patogeno possa partecipare al processo di esaurimento delle difese della pianta, assistendo quindi l’insetto nelle fasi di colonizzazione dell’ospite. Questo risultato contribuisce quindi allo sviluppo delle attuali teorie sul ruolo dei funghi associati nell’ecologia degli scolitidi. Nell’ultimo lavoro sono state studiate le correlazioni tra i metaboliti secondari delle difese costitutive del pino silvestre, e le correlazioni tra la concentrazione costitutiva e la variazione indotta dei singoli composti. I risultati hanno messo in evidenza una differenziazione di comportamento tra composti e l’assenza in generale di una correlazione inversa tra i tipi diversi di difese, al contrario di quanto previsto da alcune teorie. Nel complesso, i quattro contributi di questa tesi suggeriscono la rivalutazione di una delle attuali teorie sul ruolo dei funghi associati nella colonizzazione dell’ospite da parte degli scolitidi, e forniscono degli spunti per la comprensione del ruolo dei funghi associati nella dinamica di popolazione del vettore. Chiariscono inoltre alcuni degli aspetti dei meccanismi di difesa del pino silvestre, mettendo in evidenza la sua competitività.
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Manokaran, N. "Population dynamics of tropical forest trees." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 1988. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=59678.
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Stan, Amanda B., Thomas B. Maertens, Lori D. Daniels, and Stefan Zeglen. "Reconstructing Population Dynamics Of Yellow-Cedar In Declining Stands: Baseline Information From Tree Rings." Tree-Ring Society, 2011. http://hdl.handle.net/10150/622635.
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Yellow-cedar (Chamaecyparis nootkatensis (D. Don) Spach) forests of coastal British Columbia
are apparently experiencing decline in a manner similar to that observed in southeastern Alaska. In this pilot study, we collect tree-ring data from live and standing dead yellow-cedar trees from four declining sites on the North Coast of British Columbia. We use this data to compare growth patterns at our sites to those of yellow-cedar trees at non-declining and declining sites in southwestern British Columbia and southeastern Alaska and, in addition, to assess the possibility of reconstructing yellow-cedar population dynamics in declining stands using dendrochronology. We found coherent growth patterns (i.e. marker years and periods of suppression) among yellow-cedar chronologies from non-declining and declining sites across a broad geographic range as well as unique growth patterns between our chronologies from declining sites and those from declining sites in nearby Alaska. Using outer-ring dates of increment cores, we were able to estimate time since death of decade- to century-old standing
dead yellow-cedar trees, although the precision of the estimates was influenced by partial cambial mortality and erosion of outer rings. Our results provide baseline dendrochronological information that will be useful for planning future studies that assess growth-climate relations and reconstruct the long-term population dynamics of yellow-cedar in declining stands.
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Lind, Brandon M. "NATURAL AND ANTHROPOGENIC DRIVERS OF TREE EVOLUTIONARY DYNAMICS." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5359.
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Species of trees inhabit diverse and heterogeneous environments, and often play important ecological roles in such communities. As a result of their vast ecological breadth, trees have become adapted to various environmental pressures. In this dissertation I examine various environmental factors that drive evolutionary dynamics in threePinusspecies in California and Nevada, USA. In chapter two, I assess the role of management influence of thinning, fire, and their interaction on fine-scale gene flow within fire-suppressed populations of Pinus lambertiana, a historically dominant and ecologically important member of mixed-conifer forests of the Sierra Nevada, California. Here, I find evidence that treatment prescription differentially affects fine-scale genetic structure and effective gene flow in this species. In my third chapter, I describe the development of a dense linkage map for Pinus balfouriana which I use in chapter four to assess the quantitative trait locus (QTL) landscape of water-use efficiency across two isolated ranges of the species. I find evidence that precipitation-related variables structure the geographical range of P. balfouriana, that traits related to water-use efficiency are heritable and differentiated across populations, and associated QTLs underlying this phenotypic variation explain large proportions of total variation. In chapter five, I assess evidence for local adaptation to the eastern Sierra Nevada rain shadow within P. albicaulisacross fine spatial scales of the Lake Tahoe Basin, USA. Here, genetic variation of traits related to water availability were structured more so across populations than neutral variation, and loci identified by genome-wide association methods show elevated signals of local adaptation that track soil water availability. In chapter six, I review theory related to polygenic local adaptation and literature of genotype-phenotype associations in trees. I find that evidence suggests a polygenic basis for many traits important to conservation and industry, and I suggest paths forward to best describing such genetic bases in tree species. Overall, my results show that spatial and genetic structure of trees are often driven by their environment, and that ongoing selective pressures driven by environmental change will continue to be important in these systems.
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Kolodin, Dmitriy Pavlovich. "Dynamics of Tissue-Resident Regulatory T Cell Populations." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11555.
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In recent years, there has been a worldwide increase in obesity, which parallels a rise in pathologies, including type 2 diabetes, collectively termed the metabolic syndrome. Chronic, low-grade inflammation has been implicated as a major link between these diseases. Recent work showed the presence of a unique subset of CD4+Foxp3+ regulatory T cells residing in visceral adipose tissue (VAT Treg) with PPAR-g being the key transcription factor responsible for their phenotype and function in controlling adipose tissue inflammation and, thereby, insulin sensitivity. VAT Tregs inversely correlated with insulin resistance. In contrast, there was a dramatic age-associated increase in frequency of VAT Tregs in lean animals, correlating with continued insulin sensitivity, despite significant increases in body and adipose tissue weights. This increase in Treg frequencies was not observed in other lymphoid and non-lymphoid tissues, including the subcutaneous fat depot. We characterized this unique age-associated increase in VAT Tregs through the use of adoptive transfer models, in vivo labeling and tracking systems, parabiosis, and analysis of the T cell receptor (TCR) repertoire used by VAT Tregs. Our findings indicate that the progressive increase in VAT Tregs is not due to conversion of conventional CD4+ T cells nor to substantial infiltration of Tregs from the circulation and secondary lymphoid organs. However, by analyzing the TCR repertoire on a single-cell level we uncovered a striking oligo-clonal expansion of VAT Tregs, suggesting their accumulation results from in situ proliferation. We further showed that this accumulation is dependent on major histocompatibility complex (MHC) class II, but not on CD1d. Finally, we showed that IL-33 was able to induce proliferation of VAT Tregs. In parallel, we extended our analysis of TCR repertoire to the Treg population residing in skeletal muscle. In acute and chronic models of muscle injury, muscle-resident Tregs underwent a substantial clonal expansion, with a particular clone being detected in multiple individuals. Taken together these studies highlight the importance of proliferation as a mechanism of Treg accumulation in tissues in response to acute and chronic inflammation.
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Alalouni, Urwa [Verfasser], and Roland [Akademischer Betreuer] Brandl. "Insects in forests. Assemblages, effects of tree diversity and population dynamics / Urwa Alalouni. Betreuer: Roland Brandl." Marburg : Philipps-Universität Marburg, 2014. http://d-nb.info/1059856425/34.
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Boom, Arthur. "Diversification, evolution and population dynamics of the genus Brachystegia, a keystone tree of African miombo woodlands." Doctoral thesis, Universite Libre de Bruxelles, 2021. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/331717.
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Miombo woodlands are vast wooded savannas covering 2 million km2 in East and Southern Africa. The main feature of these landscapes with closed but not overly dense canopy is the dominance of Brachystegia, Isoberlina, and Julbernardia legume trees genera. The timing of the onset of such vegetation, mainly understood through pollen fossils remains unclear. Dated molecular phylogeny calibrated with fossils for the aforementioned genera has the potential to provide details regarding the origin of species that nowadays dominate the current woodlands and possibly of miombo vegetation as a whole. The Brachystegia is a taxonomically complex genus and is compared to the other aforementioned genera, rich in species with 21 savanna species and eight species in the African Guineo-Congolian rain forests. We aim through the thesis to identify the diversification history of Brachystegia using dated phylogenies.We first reconstruct the Brachystegia phylogeny using nearly full plastome sequences in addition to ribosomal DNA sequences. Both sequences were obtained using a genome- skimming approach. In plastid phylogeny, species represented by multiple specimens appear rarely monophyletic while plastid clades display strong geographical structuring, independently of the species. Ribosomal phylogeny conversely allowed to identify morphological clades, but the lack of DNA polymorphism prevents the reconstruction of a well-resolved Brachystegia phylogeny. The strong spatial structure detected in plastid phylogeny suggests hybridization among the different species leading to recurrent chloroplast captures. Plastomes proved very informative for tracking the past dynamics of the genus and suggest a historical westwards expansion of miombo Brachystegia during the Plio-Pleistocene. We subsequently reconstructed the evolutionary history of the genus using targeted enrichment sequencing. Phylogenetic inferences were conducted using supermatrix and summary-method approaches on a dataset encompassing around 200 individuals loci for more than 200,000 base pairs. Opposite to previous reconstructions, most species appear as monophyletic groups even if high levels of gene tree conflict between the species trees and individual gene trees are reported, suggesting either incomplete lineage sorting (ILS) and/or reticulate evolution. Introgressed plastomes, and signature of ILS and reticulation for nuclear genes when species are nevertheless relatively well delineated by nuclear genome support to some extent that Brachystegia may behave a group of interfertile but still relatively well-delineated species (i.e. syngameon). Molecular dating analysis supports a Pliocene origin for the genus, with most of the diversification events occurring during the Plio-Pleistocene. We also conducted preliminary investigations to explore the potential of the genomics approaches used in this thesis to delineate problematic species or to reconstruct the past spatial dynamic of Brachystegia in current miombo regions.Overall, through this thesis, we clarified many aspects of the taxonomically complex Brachystegia genus. Genomic data support hybridization and plastid introgression on large spatial scales, giving credit to a Brachystegia syngameon that remains yet to be furthered characterised and validated. Moreover, results indicate a fairly recent origin of dominant species of the miombo congruently with their spatial expansion documented by plastid data, giving possibly insights into the temporal and spatial evolution of the miombo woodlandsDoctorat en Sciences
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Houlgreave, John A. "Water tree dynamics and their scaling with field and frequency by analysis of time-series population data." Thesis, University of Leicester, 1996. http://hdl.handle.net/2381/34781.
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Water trees are a major form of degradation in solid organic electrical insulation subject to high AC voltages and water. The work is aimed at developing a more rigorous approach to analysing water tree data from ageing experiments on practical insulation geometries. Such data is in the form of tree length distributions and time-increasing tree number densities. Tree inception statistics are directly accessible from the data, but the effects of growth are convolved with those of inception. An approach is developed for analysing the data to quantify aspects of both inception and growth. In particular, mean growth rates and distributions of growth times can be estimated. The distribution of inception times seems to be close to exponential. Analysis shows that the effects of varying the field on the dynamics of inception depend upon whether the voltage or the insulation thickness is being varied. Increasing the frequency or decreasing thickness increases the number of possible water tree sites but decreases the inception rate from an average site. Frequency accelerates inception in a non-linear manner. Increasing the voltage both increases the number of sites and the inception rates. At frequencies close to 1 kHz, the mean length of a tree increases with the square root of growth time. Initial tree growth rates increase in a way that is consistent with a linear dependence on frequency. It is concluded that the approach developed can be applied to real data and is useful. It is expected that application of the approach to more extensive data sets would give rise to considerable advances in the empirical knowledge of the dependence of water treeing on various physical parameters which it is not possible to obtain using existing techniques.
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Giesecke, Thomas. "The Holocene Spread of Spruce in Scandinavia." Doctoral thesis, Uppsala University, Department of Earth Sciences, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4623.
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The Holocene spread of Picea abies in Scandinavia provides an excellent opportunity for detailed study of the dynamics of tree spread and population expansion. Early- and mid-Holocene macrofossil evidence for the presence of Picea abies in Scandinavia has questioned traditional interpretations of the timing and direction of its spread. This study aims to determine the pattern of the spread of Picea abies in Scandinavia from pollen and other data, to evaluate the significance of possible early outpost populations and to deduce possible factors that influenced the spread and population expansion of Picea abies in Scandinavia.
Palaeoecological investigations were carried out on the sediments of four small lakes in central Sweden to gain detailed insight into the dynamics of the spread. Holocene pollen diagrams with independent dating control were collected from Fennoscandia and adjacent areas to compare the timing of selected features of the Picea abies pollen curve. Computer models were used to test possible scenarios for the spread and Picea abies population expansion.
Picea abies entered the Scandinavian peninsula from the east at different times and by different pathways. Early-Holocene outposts can be discerned in pollen records from northwest Russia, eastern and northeastern Finland for the time before 9000 cal. BP. Pollen records from Sweden and Norway indicate small Picea abies populations after 8000 cal. BP. The mid to late-Holocene spread, which superficially resembles a front-like pattern, may in fact represent a wave of expanding populations. Disturbance through fire and human activity did not significantly influence the pattern of the spread. Changing climate parameters, slow adaptation and gene flow through seeds and pollen have to be considered as possible explanations for the late spread of the tree. Population dynamics and propagule pressure are likely to be important factors that shaped the spread of Picea abies.
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Valeriano, Diana Damasceno Barreto. "Dinâmica da floresta ombrófila mista altomontana, Campos do Jordão, São Paulo." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/41/41134/tde-25082010-114434/.
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Avaliou-se a dinâmica do componente arbóreo de uma área de Floresta Ombrófila Mista na região sudeste do Brasil, com o objetivo de verificar seu estádio sucessional e sua aderência aos modelos dinâmicos propostos para esta formação. O primeiro, modelo lozenge, ou de substituição temporal de área, propõe que a dinâmica é influenciada por padrão de recrutamento intermitente dependente de distúrbios severos, para as pioneiras longevas, geralmente gimnospermas, que dominam estruturalmente a floresta. O segundo propõe que a presença da Araucaria angustifolia é indicativa de sucessão em curso, pois esta espécie não se regenera no interior da floresta, sendo substituída por espécies latifoliadas. Um terceiro propõe recrutamento dependente de abertura de clareiras para as pioneiras longevas. Esta avaliação foi feita em três etapas: através da dinâmica da estrutura fitossociológica observou-se se ocorreram alterações na ordem de importância das espécies; com a análise demográfica buscou-se caracterizar a estrutura de tamanho das populações arbóreas e através da análise da dinâmica espacial da floresta verificou-se se a formação de clareiras permitiu recrutamento das pioneiras longevas. Os resultados mostraram uma estrutura fitossociológica sem alteração na ordem de importância das espécies, embora tenha sido observado aumento da representação de espécies umbrófilas na submata e redução das espécies de áreas mais abertas. A análise demográfica mostrou que as gimnospermas mostram estrutura de coortes, de acordo com o que é esperado para pioneiras longevas, e que no período observado não recrutaram indicando declínio para suas populações. As espécies do dossel mostraram populações em desenvolvimento e na submata foi observada dinâmica mais intensa, com aumento populacional para espécies umbrófilas. A dinâmica espacial mostrou que várias espécies independem das clareiras para recrutamento e crescimento, mas o recrutamento, a mortalidade e o enriquecimento da floresta estão correlacionados com este processo. Não foi observado recrutamento das pioneiras longevas nas clareiras presentes na área de estudo. Estes resultados indicam que a floresta está em desenvolvimento, e que sua dinâmica é influenciada pela dinâmica das pioneiras longevas. Houve indicação de aderência aos dois primeiros modelos, e na ausência de distúrbios maiores, pode-se esperar que as pioneiras longevas sejam substituídas.The dynamics of the tree component of a Mixed Ombrophylous Forest in the Southeast Brazil was evaluated to verify its successional stage and its agreement with dynamic models proposed for this formation. The first one, Lozenge model, or temporal plot replacement, proposes that the dynamics of long-lived pioneers, often gymnosperms, which structurally dominates the forest, is influenced by intermittent recruitment pattern, dependent of severe disturbances. The second proposes that the presence of Araucaria angustifolia is indicative of ongoing succession and that the A. angustifolia fate is to be substituted by broadleaf species. A third one proposes gap dependent recruitment for the long-lived pioneers. The evaluation was conducted in three phases: through the analysis of the dynamics of the phytosociological structure it was observed if changes occurred in the order of importance of the species, with a demographic analysis to characterize the size structure of the tree populations and through the analysis of the spatial dynamics of the forest it was investigated if gap formation fostered the recruitment of long-lived pioneers. The results showed a phytosociological structure with no change in the order of importance of the species, although it was observed an increase in the representation of umbrophyllous species in the understory and the reduction of sun tolerant species. The demographic analysis showed that the gymnosperms present a cohort structure in accordance with what is expected for long-lived pioneers and that during the observed time span they did not recruit, indicating a decline in their population. The canopy species presented populations in development and, in the uderstorey, a more intense dynamic was observed with population increases for the umbrophyllous species. The spatial analysis showed that many species are independent of gaps for recruitment and development but the forest recruitment, mortality and species enrichment are correlated with this process. It was not observed the recruitment of long-lived pioneers in the gaps presented in the study area. These results indicate that the forest is under development and that its dynamics is influenced by the dynamics of the long-lived pioneers. There was indication of adherence to the first two models and that, in the absence of major disturbances, it can be expected that the long-lived pioneers will be replaced.
Books on the topic "Tree Population dynamic"
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Manokaran, N. Population dynamics of trees in dipterocarp forests of peninsular Malaysia. Kuala Lumpur, Malaysia: Forest Research Institute Malaysia, 1994.
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Aberdeen-Hull Symposium on Malesian Ecology (7th 1984 Aberdeen). The dynamics of tree populations in tropical forest: Proceedings ofthe 7th Aberdeen-Hull Symposium held at the Department of Plant Science, University of Aberdeen, 22-24 September 1984. Cambridge: Cambridge University Press for INTECOL and the ICSU Press, 1987.
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Coulson, Graeme, and Mark Eldridge, eds. Macropods. CSIRO Publishing, 2010. http://dx.doi.org/10.1071/9780643098183.
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This book covers the proceedings of a major 2006 symposium on macropods that brought together the many recent advances in the biology of this diverse group of marsupials, including research on some of the much neglected macropods such as
the antilopine wallaroo, the swamp wallaby and tree-kangaroos.
More than 80 authors have contributed 32 chapters, which are grouped into four themes: genetics, reproduction and development; morphology and physiology; ecology; and management.
The book examines such topics as embryonic development, immune function, molar progression and mesial drift, locomotory energetics, non-shivering thermogenesis, mycophagy, habitat preferences, population dynamics, juvenile mortality in drought,
harvesting, overabundant species, road-kills, fertility control, threatened species, cross-fostering, translocation and reintroduction. It also highlights the application of new techniques, from genomics to GIS.
Macropods is an important reference for academics and students, researchers in molecular and ecological sciences, wildlife and park managers, and naturalists.
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Lindenmayer, David, David Blair, Lachlan McBurney, and Sam Banks. Mountain Ash. CSIRO Publishing, 2015. http://dx.doi.org/10.1071/9781486304981.
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Mountain Ash draws together exciting new findings on the effects of fire and on post-fire ecological dynamics following the 2009 wildfires in the Mountain Ash forests of the Central Highlands of Victoria. The book integrates data on forests, carbon, fire dynamics and other factors, building on 6 years of high-quality, multi-faceted research coupled with 25 years of pre-fire insights.
Topics include: the unexpected effects of fires of varying severity on populations of large old trees and their implications for the dynamics of forest ecosystems; relationships between forest structure, condition and age and their impacts on fire severity; relationships between logging and fire severity; the unexpectedly low level of carbon stock losses from burned forests, including those burned at very high severity; impacts of fire at the site and landscape levels on arboreal marsupials; persistence of small mammals and birds on burned sites, including areas subject to high-severity fire, and its implications for understanding how species in this group exhibit post-fire recovery patterns.
With spectacular images of the post-fire environment, Mountain Ash will be an important reference for scientists and students with interests in biodiversity, forests and fire.
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Jacobsen, Dean, and Olivier Dangles. Ecology of High Altitude Waters. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198736868.001.0001.
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This book brings together current knowledge on patterns and processes in the ecology of streams, lakes, and wetlands situated at more than 3000 m above sea level. The alpine headwaters of the large Asian rivers and Lake Titicaca are both well-known and iconic examples. High altitude waters include more than these systems—they are both numerous and cover many habitat types, organisms, and specializations. The book provides an overview of the variety of aquatic ecosystems and habitats, their environmental features, prominent species, and their functional adaptations to the harsh aquatic environmental conditions through to global diversity patterns along altitudinal gradients, community dynamics, species interactions and dispersal, trophic relations, and energy flows. High altitude waters are ideal systems to address a broad range of topical themes in ecology because patterns and processes are both diverse and singular. The book highlights how key concepts in ecology (e.g. the stress gradient hypothesis, the biodiversity–ecosystem functioning relationship) could find relevant study models in high altitude waters. The usual perception of pristine mountain waters is far from true, particularly in the case of high altitude waters at low latitudes where human population density is often high, and local communities live in intimate contact with, utilize, influence, and exploit these aquatic systems. Climate change effects, extinction risks of mountain populations due to vanishing glaciers, multiple human impacts, management, and conservation are also treated thoroughly. The book is richly illustrated with diagrams and numerous pictures of these poorly known systems and species.
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Salvucci, Vincenzo, and Finn Tarp. Estimating poverty transitions in Mozambique using synthetic panels: A validation exercise and an application to cross-sectional survey data. 26th ed. UNU-WIDER, 2021. http://dx.doi.org/10.35188/unu-wider/2021/964-8.
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In this paper we first validate the use of the synthetic panels technique in the context of the 2014/15 intra-year panel survey data for Mozambique, and then apply the same technique to the 1996/97, 2002/03, 2008/09, and 2014/15 cross-sectional household budget surveys for the same country. We find that in most analyses poverty rates and poverty transitions estimated using synthetic panels provide results that are close to the true values obtained using the 2014/15 panel data. With respect to intra-year poverty dynamics, we find that Mozambique has a high intra-year variability in consumption and poverty, and a very high degree of intra-year poverty immobility, with a big portion of the population remaining either in poverty or out of poverty over the whole year, with smaller percentages of individuals moving upward or downward. With respect to the 1996/97, 2002/03, 2008/09, and 2014/15 cross-sectional surveys, our results suggest that in most year-to-year comparisons there is a greater proportion of people getting out of poverty than falling into poverty, consistent with the poverty-reduction process observed, but the percentage of people staying in poverty over time appears to be substantially higher, involving about one-third of the population in most years. Further analyses on the 2008/09 and 2014/15 surveys estimate that for an individual who was in the vulnerable group in 2008/09, there is a 60 per cent probability of remaining in the same group, whereas the probability of becoming non-vulnerable is lower than the probability of entering poverty. This constitutes the first attempt to provide an insight into poverty dynamics in Mozambique using all the available survey data.
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Lloyd, Sheelagh, and Eric R. Morgan. Toxocarosis. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780198570028.003.0071.
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Toxocara canis and the syndromes of visceral and ocular larva migrans (VLM, OLM), covert toxocarosis, and neurological toxocarosis are described. Other potential agents, particularly Toxocara cati and Baylisascaris procyonis , are described. The transmission dynamics of toxocarosis to humans have never been fully elucidated, but the potential roles of pet and stray dogs, foxes, cats, and the influence of their population densities, and age demographies, are discussed in relation to contamination of the environment with eggs. Routes of infection with eggs by geophagia, poor hygiene outdoors and with dogs, and fly-borne contamination of food, and meat-borne ingestion of larvae are described. The development of prolonged in vitro culture and analyses of T. canis larval excretions/secretions (TES) and surface antigens helped explain the importance of the rapid production and shedding of TES in the prolonged course of infection and pathogenesis of disease. TES also have greatly improved serodiagnosis. However, we still have insufficient understanding of differences in the aetiology of the larvae or differences in immune responses among individuals to account for development of VLM, covert toxocarosis, or OLM in different individuals. Our understanding of the immunopathological response of the host to TES has emphasized the need for anti-inflammatory therapy in treatment; unfortunately, less information is available on the true efficacy of the anthelmintics available. The complexity of the T. canis life cycle in dogs is described and therapeutic regimens to prevent excretion of eggs by pet dogs are given. This, plus adequate control or exclusion of stray or wild canids from a property could prevent most cases of VLM. Control of infection from free-ranging stray dogs, cats and foxes, will be difficult and more data are needed to clarify the importance of these and of fly-borne and meat-borne transfer of infection to humans for control.
Book chapters on the topic "Tree Population dynamic"
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Canham, Charles D., and Stephen W. Pacala. "Linking Tree Population Dynamics and Forest Ecosystem Processes." In Linking Species & Ecosystems, 84–93. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-1773-3_9.
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Delcourt, Paul A., and Hazel R. Delcourt. "Tree Population Dynamics During the Past 20,000 Years." In Ecological Studies, 107–291. New York, NY: Springer New York, 1987. http://dx.doi.org/10.1007/978-1-4612-4740-1_5.
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Gaines, Michael S., Christopher R. Sasso, James E. Diffendorfer, and Harald Beck. "Effects of Tree Island Size and Water on the Population Dynamics of Small Mammals in the Everglades." In Tree Islands of the Everglades, 429–44. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-009-0001-1_14.
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McCormick, J. Frank. "A Review of the Population Dynamics of Selected Tree Species in the Luquillo Experimental Forest, Puerto Rico." In Ecological Studies, 224–57. New York, NY: Springer New York, 1995. http://dx.doi.org/10.1007/978-1-4612-2498-3_9.
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Liotta, G., A. Agro’, and M. C. Perricone. "Population dynamic for Aonidiella aurantii (Mask.) (Homoptera, Diaspididae) and its parasitoids on lemon trees in Sicily*." In Integrated Pest Control in Citrus-Groves, 51–58. London: CRC Press, 2021. http://dx.doi.org/10.1201/9781003079279-14.
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Allen, Michael F., and Brent D. Mishler. "A Phylogenetic Approach to Conservation: Biodiversity and Ecosystem Functioning for a Changing Globe." In Speciesism in Biology and Culture, 155–77. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-99031-2_8.
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AbstractAs late as the sixteenth century, the world was a matrix of primarily wildlands. But due to technology development and population growth, humans increasingly altered natural habitats and modified other organisms to suit our needs. The world became “all about people”—the rest of the natural world became enslaved to us. By the eighteenth and nineteenth centuries, calls emerged for conservation and the new field of ecology developed, resulting in legislation to form national parks and save endangered species (e.g., the Endangered Species Act in the US). This “one species at a time” approach can be credited with saving a number of individual taxa, but is insufficient to deal with the modern global biodiversity crisis given the urgent pressures on remaining natural lands. We argue that considerable expansion is needed in conservation biology, moving from the single species approach to an area based approach incorporating all species and a broad phylogenetic definition of biodiversity. Biodiversity should not be considered as just the arbitrary level at which species are named—instead it is the whole tree of life. We discuss newly developed approaches to multiple species habitat conservation plans and new spatial phylogenetic methods that take into account all levels in the tree of life when making conservation decisions. To protect biodiversity, we must use all the tools we have to identify and protect landscapes that allow for future dynamics, while considering the conditions of the past and present.
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Oswald, Julie N., Christine Erbe, William L. Gannon, Shyam Madhusudhana, and Jeanette A. Thomas. "Detection and Classification Methods for Animal Sounds." In Exploring Animal Behavior Through Sound: Volume 1, 269–317. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-97540-1_8.
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AbstractClassification of the acoustic repertoires of animals into sound types is a useful tool for taxonomic studies, behavioral studies, and for documenting the occurrence of animals. Classification of acoustic repertoires enables the identification of species, age, gender, and individual identity, correlations between sound types and behavior, the identification of changes in vocal behavior over time or in response to anthropogenic noise, comparisons between the repertoires of populations living in different geographic regions and environments, and the development of software tools for automated signal processing. Techniques for classification have evolved over time as technical capabilities have expanded. Initially, researchers applied qualitative methods, such as listening and visually discerning sounds in spectrograms. Advances in computer technology and the development of software for the automatic detection and classification of sounds have allowed bioacousticians to quickly find sounds in recordings, thus significantly reducing analysis time and enabling the analysis of larger datasets. In this chapter, we present software algorithms for automated signal detection (based on energy, Teager–Kaiser energy, spectral entropy, matched filtering, and spectrogram cross-correlation) as well as for signal classification (e.g., parametric clustering, principal component analysis, discriminant function analysis, classification trees, artificial neural networks, random forests, Gaussian mixture models, support vector machines, dynamic time-warping, and hidden Markov models). Methods for evaluating the performance of automated tools are presented (i.e., receiver operating characteristics and precision-recall) and challenges with classifying animal sounds are discussed.
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Quintana-Ascencio, Pedro F., Eric S. Menges, Geoffrey S. Cook, Johan Ehrlén, and Michelle E. Afkhami. "Drivers of demography: past challenges and a promise for a changed future." In Demographic Methods across the Tree of Life, 115–30. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198838609.003.0006.
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There is an urgent need to understand how populations and metapopulations respond to shifts in the environment to mitigate the consequences of human actions and global change. Identifying environmental variables/factors affecting population dynamics and the nature of their impacts is fundamental to improve projections and predictions. This chapter examines how environmental drivers, both continuous (stress) and episodic (disturbance), are incorporated in demographic modelling across many types of organisms and environments, using both observational and experimental approaches to characterise drivers. It critically summarises examples of the main approaches and identifies major accomplishments, challenges, and limitations. The chapter points to promising approaches and possible future developments. In the initial sections, models in closed systems without migration among populations are considered. The chapter then focuses on metapopulation models, emphasising the importance of understanding drivers affecting migration and differential extinction among populations. Finally, it concludes with a discussion of some important and general problems associated with assessing how population dynamics may be affected by environmental drivers that are dynamic, nonlinear, and with indirect and/or interacting effects with other drivers..
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"Dynamic Modelling of the Effects of Water, Temperature, and Light on Tree Population Spread." In GeoDynamics, 149–60. CRC Press, 2004. http://dx.doi.org/10.1201/9781420038101-15.
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Svoray, Tal, and R. Nathan. "Dynamic Modelling of the Effects of Water, Temperature, and Light on Tree Population Spread." In GeoDynamics, 125–35. CRC Press, 2004. http://dx.doi.org/10.1201/9781420038101.ch10.
Full textConference papers on the topic "Tree Population dynamic"
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Hillman, Lloyd W. "Coherent optical interactions in semiconductor lasers." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oam.1987.wo10.
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Fluctuations in the amplitude, frequency, and polarization of the light emitted by semiconductor laser diodes limit the performance and reliability of many optical systems, such as communication links, optical radar, and optical disk read/write memories. Although it seems logical to explain this noise as random or stochastic, such erratic behavior can arise from completely deterministic models of lasers that retain the dynamics of the coherently induced polarization. This has been shown to be true for the simple model of a laser based on a two-level resonance, which results in the coupled Maxwell-Bloch equations. These equations are termed coherent because the Bloch equations describe, not only the inversion, but also the induced polarization of the gain media. The Maxwell-Bloch equations predict an array of instabilities and novel operation conditions for a laser: the output light may oscillate regularly or pulsate chaotically. Such behavior is not found in the incoherent population rate equation that adiabatically eliminated the dynamics of the polarization. However, the Maxwell-Bloch equations apply only to dilute materials in which the total gain is described by an ensemble average over many noninteracting molecules, such as gas lasers.
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Olasumboye, Adewale, Gbadebo Owolabi, Olufemi Koya, Horace Whitworth, and Nadir Yilmaz. "Comparative Study of the Dynamic Behavior of AA2519 Aluminum Alloy in T6 and T8 Temper Conditions." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10978.
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Abstract This study investigates the dynamic response of AA2519 aluminum alloy in T6 temper condition during plastic deformation at high strain rates. The aim was to determine how the T6 temper condition affects the flow stress response, strength properties and microstructural morphologies of the alloy when impacted under compression at high strain rates. The specimens (with aspect ratio, L/D = 0.8) of the as-cast alloy used were received in the T8 temper condition and further heat-treated to the T6 temper condition based on the standard ASTM temper designation procedures. Split-Hopkinson pressure bar experiment was used to generate true stress-strain data for the alloy in the range of 1000–3500 /s strain rates while high-speed cameras were used to monitor the test compliance with strain-rate constancy measures. The microstructures of the as received and deformed specimens were assessed and compared for possible disparities in their initial microstructures and post-deformation changes, respectively, using optical microscopy. Results showed no clear evidence of strain-rate dependency in the dynamic yield strength behavior of T6-temper designated alloy while exhibiting a negative trend in its flow stress response. On the contrary, AA2519-T8 showed marginal but positive response in both yield strength and flow behavior for the range of strain rates tested. Post-deformation photomicrographs show clear disparities in the alloys’ initial microstructures in terms of the second-phase particle size differences, population density and, distribution; and in the morphological changes which occurred in the microstructures of the different materials during large plastic deformation. AA2519-T6 showed a higher susceptibility to adiabatic shear localization than AA2519-T8, with deformed and bifurcating transformed band occurring at 3000 /s followed by failure at 3500 /s.
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Schumacher, Melissa. "Modelos de desarrollo socio-territorial: caso de estudio: Cholula, México." In Seminario Internacional de Investigación en Urbanismo. Barcelona: Facultad de Arquitectura. Universidad de la República., 2015. http://dx.doi.org/10.5821/siiu.6102.
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La Ciudad de Cholula representa un ejemplo icónico del desarrollo periurbano en México de ciudades medias inmersas en un entorno metropolitano. La particular heterogeneidad de Cholula como región sagrada, estudiantil y de servicios, se ha ido conformando a través de tres tipos de modelo socio-territorial: el compacto, el rural y el metropolitano; estos modelos se integran a través de diferentes patrones de uso de suelo. La transformación urbana de Cholula se originó en territorio ejidal, donde su expropiación en la década de 1990 y la implementación del Programa de Desarrollo Regional Angelópolis generaron diversos detonadores peri-urbanos, como cambios en las dinámicas poblacionales, especulación inmobiliaria, dispersión de localidades, abandono de las actividades agrícolas y consumo desmedido del territorio. Estos detonadores generaron cambios en los patrones de uso de suelo que van desde los núcleos urbanos compactos hasta las localidades rurales dispersas a las nuevas centralidades urbanas. The City of Cholula represents an iconic example of peri-urban development in Mexican middle-size cities. Cholula has a particular heterogeneity as a sacred, student, and services region. Its context is being developed through three socio-spatial models: the compact, the rural, and the metropolitan; each integrated with patterns of land use. The urban transformation of Cholula began in 1990 with the expropriation of ejido and agricultural land and the implementation of the Regional Development Plan Angelópolis. All of these triggered peri-urbanization development, like changes in populations’ dynamics, real estate speculation, urban sprawl, abandon of agricultural activities, and a wasteful consumption of land. These facts generated changes in the patterns of land use, from compact-urban cores, sprawl rural localities, to new urban centralities.
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Arizaga, Ximena. "La renovación urbana como reflejo de distintas conceptualizaciones del espacio: Santiago Centro: más de un Siglo de Políticas de Renovación Urbana." In Seminario Internacional de Investigación en Urbanismo. Barcelona: Facultad de Arquitectura. Universidad de la República, 2015. http://dx.doi.org/10.5821/siiu.6185.
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La renovación urbana es un campo de estudio que ha cobrado relevancia en un contexto de urbanización creciente que alcanzaba a nivel mundial 53% el año 2013 (Banco Mundial). En esta perspectiva, su estudio cobra interés tanto para comprender espacios otrora renovados pero plenamente vigentes en la ciudad como para abordar el desafío de renovación que plantea el crecimiento de la población urbana. Se propone una periodización de las políticas de renovación urbana para el caso de Santiago de Chile, que busca acotar y comprender las diferencias y similitudes entre iniciativas que abordan esta dinámica urbana.
Se postula la existencia de tres periodos históricos que dan cuenta de la aplicación de esta política pública en Chile: un primer periodo que responde a una lógica donde domina el deseo de estructuración de la ciudad (1872-1939); un segundo periodo que responde a una lógica dominante de escasez de vivienda (1965-1976) y un tercer periodo marcado por el neoliberalismo y la lógica de re-poblamiento y gestión del suelo (1985-a la fecha). Urban renewal is a field of study that has gained importance in a context of growing urbanization worldwide that reached 53% in 2013 (World Bank). In this perspective, studying it is interesting to understand spaces once renovated and to assume the challenge posed by the renewal in a context of urban population growth. Periods of urban renewal are proposed for the case of Santiago de Chile, which seeks to define and understand the differences and similarities between initiatives addressing this urban dynamic.
Three periods are proposed for the historical application of urban renewal policies in Santiago: a first period that responds to a logic dominated by the aims to structure the city (1872-1939); a second period that responds to a dominant logic of housing shortages (1965-1976) and a third period conditioned by neoliberalism and the logic of re-settlement and land management (1985-present).
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Sankaran, Sathish, Diego Molinari, Hardik Zalavadia, Trevor Stoddard, Wenyue Sun, Gagan Singh, and Chris James. "Unlocking Unconventional Production Optimization Opportunities Using Reduced Physics Models for Well Performance Analysis – Case Study." In International Petroleum Technology Conference. IPTC, 2022. http://dx.doi.org/10.2523/iptc-22493-ms.
Full textAbstract:
Abstract Economic pressure to improve production efficiency in unconventional reservoirs has met a stiff challenge to scale up traditional reservoir modeling methods to the entire field for quantifying well performance. The main reasons are lack of availability of key reservoir and well parameters and difficulty to setup and maintain models because of the large well count and rapid pace of operations. As a result, decline curve analysis is still the prevailing method for large scale evaluations, which does not consider routine pressure variations and operational constraints. Analytical rate transient (RTA) models warrant identification of flow regimes and geometrical assumptions (well and fractures) to apply discrete analytical models for various flow segments. This inherent limitation of RTA makes it interpretive and not conducive to fieldscale application, besides often lacking necessary inputs for all wells. It is desirable to have better understanding through a robust and consistent well performance analysis method at field scale to unlock significant production optimization opportunities with existing field infrastructure and investment. We have applied a reduced physics formulation based on Dynamic Drainage Volume (DDV) using commonly measured data for most wells (namely, flowback data, daily production rates, and wellhead pressure) to calculate continuous pressure depletion, transient productivity index (PI) and inflow performance relationship (IPR). This transient well performance (TWP) method eliminates the surface and wellbore operational impacts to extract the true reservoir signal that can be used for robust well performance analysis and forecasting. We applied the TWP method in multiple basins with large well counts (more than 1000 wells) producing under a variety of methods. In this paper, we present several case studies illustrating various production optimization opportunities, focusing on naturally flowing and gas-lifted wells. The fluid properties and bottomhole pressure estimated using data-driven methods for all wells provided excellent match with blind data (PVT lab reports and downhole gauge data). The TWP method normalizes reservoir and completion quality to extract valuable insights on effectiveness of well and completions design in the presence of varying geological and fluid properties. The transient PI and dynamic IPR results provided valuable insights on how and when to select various artificial lift systems. During gas lift, we identified several wells that were over-injecting gas volumes at higher compressor discharge head, with line of sight to significant operational cost savings and reduced energy consumption. The proposed methodology combines pragmatic use of physics and data-driven methods to solve a critical need for analyzing unconventional reservoirs. Field application of the novel DDV method on large well population has been quite successful in identifying various optimization opportunities that would not have been possible, timely, or repeatable with other traditional methods.
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Ortolani, Chiara. "Morfologia urbana, trasporti, energia: indicatori di impatto." In International Conference Virtual City and Territory. Roma: Centre de Política de Sòl i Valoracions, 2014. http://dx.doi.org/10.5821/ctv.7910.
Full textAbstract:
La mobilità svolge un ruolo vitale per il mercato interno, per l’occupazione e, più in generale per
la qualità della vita dei cittadini. Rivolgendo l'attenzione al contesto mondiale, europeo e
nazionale si vede come sia divenuta una necessità sempre crescente: la mobilità media per
persona in Europa, misurata in passeggeri-chilometro per abitante, è aumentata del 7% tra il
2000 e il 2008 e si prevede che nel 2050 i passeggeri-km nell’Europa OECD saranno il doppio
rispetto al 2000. Per ciò che riguarda il trasporto merci la domanda ha continuato a crescere
oltre il PIL negli ultimi dieci anni (EC, 2011).
L’attuale modello di trasporto è basato però sull'uso dei combustibili fossili e sul predominio del
trasporto su strada, sia per le merci che per i passeggeri (EC, 2011) e inoltre una larga parte
della mobilità oggi esistente potrebbe essere evitata (McLellan & Marshall, 1998). Di
conseguenza, tale modello è responsabile del 23% dell’energia consumata in Europa. Circa i
tre quarti dipendono dal trasporto su strada (IPCC, 2007) e il consumo energetico, in questo
settore, si stima che aumenterà circa dell’80% entro il 2030.
In conseguenza del fatto che l’energia consumata in questo settore proviene per il 96% dal
petrolio e dai suoi derivati (IPCC, 2007; EC, 2011) questo stesso è responsabile di elevate
emissioni di CO2 e altre sostanze clima-alteranti, dell'aumento della temperatura e di rilevanti
problemi di salute nelle popolazioni esposte (U.S. EPA, 2010). La forte dipendenza dal petrolio
potrebbe inoltre portare a conseguenze severe sulle possibilità di approvvigionamento di merci
e spostamento dei cittadini, sulla sicurezza economica e la competitività globale ed europea nei
decenni futuri (EC, 2011; U.S. Joint Forces Command, 2010). La maggior parte degli
spostamenti sono interni alle aree urbane e, per il settore dei trasporti, queste sono le aree che
influiscono di più sui cambiamenti climatici e sui consumi energetici globali.
La città può essere assimilata ad un organismo (Samaniego & Moses, 2008) e gli spostamenti
che si compiono in essa, affinché siano efficaci, devono avvenire attraverso una rete che
rappresenti una configurazione ordinata di relazioni -o connettività- (Capra, 1996) che implica
una certa forma, una struttura definita (con il rispettivo schema) e uno o più processi specifici
(Samaniego & Moses, 2008). Le caratteristiche che osserviamo oggi negli organismi sono il
risultato di milioni di anni di evoluzione verso l’ottimizzazione delle strutture: minimizzazione
dell’energia spesa per la distribuzione delle risorse e massimizzazione del rendimento.
Tendono quindi a minimizzare il loro grado di entropia. Per arrivare ad una configurazione del
tessuto connettivo urbano che possa minimizzare il suo grado di entropia è necessario innanzi
tutto individuare un insieme di indicatori sulla base dei quali sia possibile caratterizzare lo
spazio stesso e che rendano possibili analisi dinamiche della morfologia urbana. In quest’ottica,
questo contributo si pone quindi come obiettivo quello di individuare un primo set di indicatori
significativi derivati dal confronto tra le caratteristiche delle reti vascolari di un organismo e il
tessuto connettivo urbano. The mobility plays a very important role for the internal market, employment and, more
generally, the citizens’s life quality that takes great advantages from an effective and
sustainable transport system. In the last twenty years, mobility has become an ever increasing
necessity: the average mobility per capita in Europe, measured in passenger-kilometres per
capita, is increased by 7% between 2000 and 2008 and it is expected that in 2050 the
passenger-km OECD Europe will double compared to 2000. Furthermore demand for resources and food is continued to grow well beyond the GDP over the past decade (EC, 2011),
enhancing thus the freight.
The current transport model that responds to this mobility demand, which also includes a large
part of trips that could be avoided (McLellan & Marshall, 1998), is based on the dominance of
road transport and use of fossil fuels (EC, 2011), both for freight and transport of passengers.
As a conseguence this transport model is accountable for 23% of energy consumed in Europe,
and about three quarters of which depends on road transport (IPCC, 2007) It is estimated that
energy consumption in this sector will increase by around 80% for 2030.
In this sector, the energy consumed originates of 96% from oil and its products (IPCC, 2007;
EC, 2011; Lerch, 2011). Therefore, the transport sector is responsible for high emissions of
CO2 and other climate-altering gases, for the temperature increase and for significant health
problems in population directly exposed to oil-derived pollutants(U.S. EPA, 2010). The strong
dependence on oil may also have important consequences on the resource supply and mobility
of citizens for the next decades (EC, 2011; U.S. Joint Forces Command, 2010). The majority of
trips are internal to the urban areas that are affected by this congestion, local air pollution, road
accidents and social harms. Finally, urban trips have a major influence on climate change and
energy consumption at the global level.
Samaniego & Moses (2008) show the similarities existing between cities and organisms. Urban
trips are effective if are done through a network representing an ordered configuration of
relationships -connectivity-(Capra, 1996) which implies a particular shape, definite structure and
one or more specific processes. The characteristics that are observed in organisms today are
the result of millions of years of evolution that led to optimized structures that tend to minimize
the energy cost for resource allocation thus maximizing their productivity. Therefore, the
organisms tend to minimize their degree of entropy. To arrive at a configuration of urban
connective tissue that can minimize its level of entropy is first necessary to identify a set of
indicators on the basis of which it is possible to characterize the space and make possible
dynamic analysis of urban morphology. In this context, the aim of this contribution is to identify a
first set of meaningful indicators derived from a comparison of the characteristics of the vascular
networks of an organism with the urban connective tissue.
Reports on the topic "Tree Population dynamic"
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Droby, Samir, Joseph W. Eckert, Shulamit Manulis, and Rajesh K. Mehra. Ecology, Population Dynamics and Genetic Diversity of Epiphytic Yeast Antagonists of Postharvest Diseases of Fruits. United States Department of Agriculture, October 1994. http://dx.doi.org/10.32747/1994.7568777.bard.
Full textAbstract:
One of the emerging technologies is the use of microbial agents for the control of postharvest diseases of fruits and vegetables. A number of antagonistic microorganisms have been discovered which have the potential to effectively control postharvest diseases. Some of this technology has been patented and commercial products such as AspireTM (Ecogen Corporatin, Langhorne, PA, USA), Biosave 10TM and Biosave 11TM (Ecoscience Inc., Worchester, MA, USA) have been registered for commercial use. The principal investigator of this project was involved in developing the yeast-based biofungicide-AspireTM and testing its efficacy under commercial conditions. This research project was initiated to fill the gap between the knowledge available on development and commercial implementation of yeast biocontrol agents and basic understanding of various aspects related to introducing yeast antagonists to fruit surfaces, along with verification of population genetics. The main objectives of this study were: Study ecology, population dynamics and genetic diversity of the yeast antagonists Candida guilliermondii, C. oleophila, and Debaryomyces hansenii, and study the effect of preharvest application of the yeast antagonist C. oleophila naturally occurring epiphytic microbial population and on the development of postharvest diseases of citrus fruit during storage. Our findings, which were detailed in several publications, have shown that an epiphytic yeast population of grapefruit able to grow under high osmotic conditions and a wide range of temperatures was isolated and characterized for its biocontrol activity against green mold decay caused by Penicillium digitatum. Techniques based on random amplified polymorphic DNA (RAPD) and arbitrary primed polymerase chain reaction (ap-PCR), as well as homologies between sequences of the rDNA internal transcribed spacers (ITS) and 5.8S gene, were used to characterize the composition of the yeast population and to determine the genetic relationship among predominant yeast species. Epiphytic yeasts exhibiting the highest biocontrol activity against P. digitatum on grapefruit were identified as Candida guilliermondii, C. oleophila, C. sake, and Debaryomyces hansenii, while C. guilliermondii was the most predominant species. RAPD and ap-PCR analysis of the osmotolerant yeast population showed two different, major groups. The sequences of the ITS regions and the 5.8S gene of the yeast isolates, previously identified as belonging to different species, were found to be identical. Following the need to develop a genetically marked strain of the yeast C. oleophila, to be used in population dynamics studies, a transformation system for the yeast was developed. Histidine auxotrophy of C. oloephila produced using ethyl methanesulfonate were transformed with plasmids containing HIS3, HIS4 and HIS5 genes from Saccharomyces cerevisiae. In one mutant histidin auxotrophy was complemented by the HIS5 gene of S. cerevisiae is functionally homologous to the HIS5 gene in V. oleophila. Southern blot analysis showed that the plasmid containing the S. cerevisiae HIS5 gene was integrated at a different location every C. oleophila HIS+ transformant. There were no detectable physiological differences between C. oleophila strain I-182 and the transformants. The biological control ability of C. oleophila was not affected by the transformation. A genetically marked (with b-glucuronidase gene) transformant of C. oleophila colonized wounds on orange fruits and its population increased under field conditions. Effect of preharvest application of the yeast C. oleophila on population dynamics of epiphytic microbial population on wounded and unwounded grapefruit surface in the orchard and after harvest was also studied. In addition, the effect of preharvest application of the yeast C. oleophila on the development of postharvest decay was evaluated. Population studies conducted in the orchard showed that in control, non-treated fruit, colonization of wounded and unwounded grapefruit surface by naturally occurring filamentous fungi did not vary throughout the incubation period on the tree. On the other hand, colonization of intact and wounded fruit surface by naturally occurring yeasts was different. Yeasts colonized wounded surface rapidly and increased in numbers to about two orders of magnitude as compared to unwounded surface. On fruit treated with the yeast and kept on the tree, a different picture of fungal and yeast population had emerged. The detected fungal population on the yeast-treated intact surface was dramatically reduced and in treated wounds no fungi was detected. Yeast population on intact surface was relatively high immediately after the application of AspireTM and decreased to than 70% of that detected initially. In wounds, yeast population increased from 2.5 x 104 to about 4x106 after 72 hours of incubation at 20oC. Results of tests conducted to evaluate the effect of preharvest application of AspireTM on the development of postharvest decay indicated the validity of the approach.
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Bar-Joseph, Moshe, William O. Dawson, and Munir Mawassi. Role of Defective RNAs in Citrus Tristeza Virus Diseases. United States Department of Agriculture, September 2000. http://dx.doi.org/10.32747/2000.7575279.bard.
Full textAbstract:
This program focused on citrus tristeza virus (CTV), the largest and one of the most complex RNA-plant-viruses. The economic importance of this virus to the US and Israeli citrus industries, its uniqueness among RNA viruses and the possibility to tame the virus and eventually turn it into a useful tool for the protection and genetic improvement of citrus trees justify these continued efforts. Although the overall goal of this project was to study the role(s) of CTV associated defective (d)-RNAs in CTV-induced diseases, considerable research efforts had to be devoted to the engineering of the helper virus which provides the machinery to allow dRNA replication. Considerable progress was made through three main lines of complementary studies. For the first time, the generation of an engineered CTV genetic system that is capable of infecting citrus plants with in vitro modified virus was achieved. Considering that this RNA virus consists of a 20 kb genome, much larger than any other previously developed similar genetic system, completing this goal was an extremely difficult task that was accomplished by the effective collaboration and complementarity of both partners. Other full-length genomic CTV isolates were sequenced and populations examined, resulting in a new level of understanding of population complexities and dynamics in the US and Israel. In addition, this project has now considerably advanced our understanding and ability to manipulate dRNAs, a new class of genetic elements of closteroviruses, which were first found in the Israeli VT isolate and later shown to be omnipresent in CTV populations. We have characterized additional natural dRNAs and have shown that production of subgenomic mRNAs can be involved in the generation of dRNAs. We have molecularly cloned natural dRNAs and directly inoculated citrus plants with 35S-cDNA constructs and have shown that specific dRNAs are correlated with specific disease symptoms. Systems to examine dRNA replication in protoplasts were developed and the requirements for dRNA replication were defined. Several artificial dRNAs that replicate efficiently with a helper virus were created from infectious full-genomic cDNAs. Elements that allow the specific replication of dRNAs by heterologous helper viruses also were defined. The T36-derived dRNAs were replicated efficiently by a range of different wild CTV isolates and hybrid dRNAs with heterologous termini are efficiently replicated with T36 as helper. In addition we found: 1) All CTV genes except of the p6 gene product from the conserved signature block of the Closteroviridae are obligate for assembly, infectivity, and serial protoplast passage; 2) The p20 protein is a major component of the amorphous inclusion bodies of infected cells; and 3) Novel 5'-Co-terminal RNAs in CTV infected cells were characterized. These results have considerably advanced our basic understanding of the molecular biology of CTV and CTV-dRNAs and form the platform for the future manipulation of this complicated virus. As a result of these developments, the way is now open to turn constructs of this viral plant pathogen into new tools for protecting citrus against severe CTV terms and development of virus-based expression vectors for other citrus improvement needs. In conclusion, this research program has accomplished two main interconnected missions, the collection of basic information on the molecular and biological characteristics of the virus and its associated dRNAs toward development of management strategies against severe diseases caused by the virus and building of novel research tools to improve citrus varieties. Reaching these goals will allow us to advance this project to a new phase of turning the virus from a pathogen to an ally.
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Hovav, Ran, Peggy Ozias-Akins, and Scott A. Jackson. The genetics of pod-filling in peanut under water-limiting conditions. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7597923.bard.
Full textAbstract:
Pod-filling, an important yield-determining stage is strongly influenced by water stress. This is particularly true for peanut (Arachishypogaea), wherein pods are developed underground and are directly affected by the water condition. Pod-filling in peanut has a significant genetic component as well, since genotypes are considerably varied in their pod-fill (PF) and seed-fill (SF) potential. The goals of this research were to: Examine the effects of genotype, irrigation, and genotype X irrigation on PF and SF. Detect global changes in mRNA and metabolites levels that accompany PF and SF. Explore the response of the duplicate peanut pod transcriptome to drought stress. Study how entire duplicated PF regulatory processes are networked within a polyploid organism. Discover locus-specific SNP markers and map pod quality traits under different environments. The research included genotypes and segregating populations from Israel and US that are varied in PF, SF and their tolerance to water deficit. Initially, an extensive field trial was conducted to investigate the effects of genotype, irrigation, and genotype X irrigation on PF and SF. Significant irrigation and genotypic effect was observed for the two main PF related traits, "seed ratio" and "dead-end ratio", demonstrating that reduction in irrigation directly influences the developing pods as a result of low water potential. Although the Irrigation × Genotype interaction was not statistically significant, one genotype (line 53) was found to be more sensitive to low irrigation treatments. Two RNAseq studies were simultaneously conducted in IL and the USA to characterize expression changes that accompany shell ("source") and seed ("sink") biogenesis in peanut. Both studies showed that SF and PF processes are very dynamic and undergo very rapid change in the accumulation of RNA, nutrients, and oil. Some genotypes differ in transcript accumulation rates, which can explain their difference in SF and PF potential; like cvHanoch that was found to be more enriched than line 53 in processes involving the generation of metabolites and energy at the beginning of seed development. Interestingly, an opposite situation was found in pericarp development, wherein rapid cell wall maturation processes were up-regulated in line 53. Although no significant effect was found for the irrigation level on seed transcriptome in general, and particularly on subgenomic assignment (that was found almost comparable to a 1:1 for A- and B- subgenomes), more specific homoeologous expression changes associated with particular biosynthesis pathways were found. For example, some significant A- and B- biases were observed in particular parts of the oil related gene expression network and several candidate genes with potential influence on oil content and SF were further examined. Substation achievement of the current program was the development and application of new SNP detection and mapping methods for peanut. Two major efforts on this direction were performed. In IL, a GBS approach was developed to map pod quality traits on Hanoch X 53 F2/F3 generations. Although the GBS approach was found to be less effective for our genetic system, it still succeeded to find significant mapping locations for several traits like testa color (linkage A10), number of seeds/pods (A5) and pod wart resistance (B7). In the USA, a SNP array was developed and applied for peanut, which is based on whole genome re-sequencing of 20 genotypes. This chip was used to map pod quality related traits in a Tifrunner x NC3033 RIL population. It was phenotyped for three years, including a new x-ray method to phenotype seed-fill and seed density. The total map size was 1229.7 cM with 1320 markers assigned. Based on this linkage map, 21 QTLs were identified for the traits 16/64 weight, kernel percentage, seed and pod weight, double pod and pod area. Collectively, this research serves as the first fundamental effort in peanut for understanding the PF and SF components, as a whole, and as influenced by the irrigation level. Results of the proposed study will also generate information and materials that will benefit peanut breeding by facilitating selection for reduced linkage drag during introgression of disease resistance traits into elite cultivars. BARD Report - Project4540 Page 2 of 10