Processes occurring during the early life of marine fishes encompassing the larval, settlement, and juvenile stages can have important impacts on recruitment and subsequent population dynamics. Yet these life stages remain poorly understood, especially in coral reef-associated species of commercial and recreational fisheries interest. Two years (2003-2004) of monthly sampling of 17 stations along a transect spanning the east-west axis of the Straits of Florida revealed consistent spatiotemporal patterns in larval abundance, growth, and mortality of several snapper and barracuda species. Much of the species-specific variability in these patterns tracked adult life history, and spatial (several snapper species) and temporal (Sphyraena barracuda) patterns in larval growth were related to larval food availability. While no patterns were identified in larval mortality rates, tethering experiments examining relative rates of predation on late-stage Lutjanus griseus larvae in surface waters of the lower Florida Keys revealed that relative predation rate and probability of predation in oceanic areas seaward of the reef was significantly greater than over reef or nearshore seagrass/hardbottom habitats. The combined effects of mortality during these early stages in concert with variability in early life traits caused selective mortality to be pervasive throughout the early life stages of snappers and barracudas. Patterns in selective mortality were investigated by tracking and repeatedly sampling several cohorts of larvae in 2007 and 2008, and for the first time in tropical reef fishes, linking young pelagic larvae with settlement-stage fish and juveniles. In agreement with the growth-mortality hypothesis, large size-at-hatch and fast larval growth conveyed a survival advantage in most species examined, but several switches in the direction of selection with ontogeny and over time occurred, and were contrary to this hypothesis. Consistent patterns of trait-mediated selective mortality lower trait variability in the surviving population, while inconsistencies in these patterns may contribute to the high degree of variability that characterizes these early life stages. Results presented in this dissertation help fill knowledge gaps critical to the understanding and modeling of dispersal and connectivity in several economically valuable snapper and barracuda species. In addition, the identification of life history traits important to the survival of individuals through the larval and into the juvenile stage, has implications for future management of these ecologically and economically valuable species.

Tendências atuais em restauração evidenciam a importância de propiciar o retorno das funções ecossistêmicas e ecológicas. Porém muitas áreas possuem baixo potencial para reestabelecimento de processos ecológicos devido à perda da resiliência, o que faz da restauração ecológica um processo desafiador. Para o sucesso das atividades propostas, é essencial que no decorrer do projeto os sistemas sejam capazes de retomar sua trajetória sucessional e dinâmica temporal, sem necessidade de futuras intervenções humanas. O objetivo desta tese foi avaliar os processos iniciais de restauração ecológica em áreas degradadas por mineração de carvão, através da análise de trajetórias sucessionais envolvendo: (1) taxas de crescimento e mortalidade de mudas nativas introduzidas e sua relação com atributos funcionais de plantas; (2) chuva de sementes associada, ou não, ao uso de poleiros artificiais e sua relação com regenerantes de espécies lenhosas; e (3) regeneração natural e sua relação com fatores abióticos e bióticos. Mudas de espécies nativas introduzidas sob condições limitantes (devido ao alto nível de impacto) apresentaram diferentes performances e relações com atributos, por vezes distintas do esperado para espécies sob condições naturais. A limitação de sementes nas áreas em restauração pode ser, potencialmente, reduzida pelo uso de poleiros artificiais, aumentando especialmente sementes de espécies não-pioneiras e zoocóricas. No entanto, não foi verificada relação entre a chuva de sementes e a taxa de recrutamento. Fatores abióticos, relacionados à composição química do solo, e fatores bióticos, como a presença de gramíneas exóticas, foram as variáveis com maior influência negativa sobre a regeneração natural. Este estudo evidencia a possibilidade do retornar do processo de sucessão natural em áreas de mata ciliar que foram profundamente alteradas por mineração de carvão, em um tempo relativamente curto. Entretanto, recomendamos o uso de objetivos realísticos e intermediários, bem como monitoramentos detalhados nas fases iniciais. / In current projects of ecological restoration, the return of ecosystem functions and natural processes is an important aim. However, many areas have lost their resilience due the high damage they have been submitted to, and this makes the ecological restoration a challenging process. For the success of the proposed activities, it is essential that during the project, the ecosystem can return to its successional trajectory without necessity of strong human intervention in the future. The goal of this thesis was to evaluate the initial processes of ecological restoration in areas severally degraded by coal mining, through analyses of successional trajectories regarding: (1) growth and mortality rates of planted samplings and their relationship to functional traits; (2) seed rain, associated or not, to perches and its relationship to natural regeneration of woody species; and (3) natural regeneration of woody species and its relationship to abiotic and biotic variables. Planted saplings under limited conditions (due the high impact of mining) showed to have distinct performance and trait relationships, somewhat different to the expected for species under natural conditions. The study indicates that the limitation of seeds in areas under ecological restoration can be reduced by the use of perches, increasing especially the number of seeds of non-pioneer and zoocoric species. Nevertheless, we did not found a relation between seed rain and recruitment rate. Soil chemistry (abiotic variable) and the cover of exotic grasses (biotic variable) were the variables with the strongest negative impact on natural regeneration. We conclude that it is possible to return to successional processes in areas of riparian forest severely damaged by coal mining activities in a relatively short time, but recommend the use of realistic, intermediate restoration goals and detailed monitoring in early restoration phases.

Tendências atuais em restauração evidenciam a importância de propiciar o retorno das funções ecossistêmicas e ecológicas. Porém muitas áreas possuem baixo potencial para reestabelecimento de processos ecológicos devido à perda da resiliência, o que faz da restauração ecológica um processo desafiador. Para o sucesso das atividades propostas, é essencial que no decorrer do projeto os sistemas sejam capazes de retomar sua trajetória sucessional e dinâmica temporal, sem necessidade de futuras intervenções humanas. O objetivo desta tese foi avaliar os processos iniciais de restauração ecológica em áreas degradadas por mineração de carvão, através da análise de trajetórias sucessionais envolvendo: (1) taxas de crescimento e mortalidade de mudas nativas introduzidas e sua relação com atributos funcionais de plantas; (2) chuva de sementes associada, ou não, ao uso de poleiros artificiais e sua relação com regenerantes de espécies lenhosas; e (3) regeneração natural e sua relação com fatores abióticos e bióticos. Mudas de espécies nativas introduzidas sob condições limitantes (devido ao alto nível de impacto) apresentaram diferentes performances e relações com atributos, por vezes distintas do esperado para espécies sob condições naturais. A limitação de sementes nas áreas em restauração pode ser, potencialmente, reduzida pelo uso de poleiros artificiais, aumentando especialmente sementes de espécies não-pioneiras e zoocóricas. No entanto, não foi verificada relação entre a chuva de sementes e a taxa de recrutamento. Fatores abióticos, relacionados à composição química do solo, e fatores bióticos, como a presença de gramíneas exóticas, foram as variáveis com maior influência negativa sobre a regeneração natural. Este estudo evidencia a possibilidade do retornar do processo de sucessão natural em áreas de mata ciliar que foram profundamente alteradas por mineração de carvão, em um tempo relativamente curto. Entretanto, recomendamos o uso de objetivos realísticos e intermediários, bem como monitoramentos detalhados nas fases iniciais. / In current projects of ecological restoration, the return of ecosystem functions and natural processes is an important aim. However, many areas have lost their resilience due the high damage they have been submitted to, and this makes the ecological restoration a challenging process. For the success of the proposed activities, it is essential that during the project, the ecosystem can return to its successional trajectory without necessity of strong human intervention in the future. The goal of this thesis was to evaluate the initial processes of ecological restoration in areas severally degraded by coal mining, through analyses of successional trajectories regarding: (1) growth and mortality rates of planted samplings and their relationship to functional traits; (2) seed rain, associated or not, to perches and its relationship to natural regeneration of woody species; and (3) natural regeneration of woody species and its relationship to abiotic and biotic variables. Planted saplings under limited conditions (due the high impact of mining) showed to have distinct performance and trait relationships, somewhat different to the expected for species under natural conditions. The study indicates that the limitation of seeds in areas under ecological restoration can be reduced by the use of perches, increasing especially the number of seeds of non-pioneer and zoocoric species. Nevertheless, we did not found a relation between seed rain and recruitment rate. Soil chemistry (abiotic variable) and the cover of exotic grasses (biotic variable) were the variables with the strongest negative impact on natural regeneration. We conclude that it is possible to return to successional processes in areas of riparian forest severely damaged by coal mining activities in a relatively short time, but recommend the use of realistic, intermediate restoration goals and detailed monitoring in early restoration phases.

This thesis investigates an influence of environmental variables (temperature and food availability) on development and growth of the first three nymphal stages of Ilyocoris cimicoides Linnaeus, 1758 Individuals were housed individually in experimental cages from eklosis into adulthood. Experiments were carried out in a combination of four different temperatures (17 ?, 19 ?, 22 ? and 25 ? C) and two different modes of food availability (full-fed every day, red-fed every other day) (in eight treatments). The temperature significantly influenced the length of nymphal development. According to our expectation, shortest development was achieved in individuals reared at 25° C. Development period was prolonged by decreasing temperatures. Unpredictably, the nymphs of the 3rd instar had longest development at the lowest temperatures (17 ? C) whereas nymphal development of the 1st and 2nd instars ran faster Both, the lowest- (17 ? C) as well as the highest used temperature (25 ? C) are probably very close to the temperature limits, that corresponds to the limits of postembryonic development. The optimum temperature for development was 22 ? C. Furthermore, it has been found that food availability should also significantly affect growth and development. Surprisingly, less mortality was observed in individuals reared in reduced feeding treatment, except the only case - nymphs reared in low temperature (19 ? C), where higher mortality was found in individuals reared at the same food availability.

Tendências atuais em restauração evidenciam a importância de propiciar o retorno das funções ecossistêmicas e ecológicas. Porém muitas áreas possuem baixo potencial para reestabelecimento de processos ecológicos devido à perda da resiliência, o que faz da restauração ecológica um processo desafiador. Para o sucesso das atividades propostas, é essencial que no decorrer do projeto os sistemas sejam capazes de retomar sua trajetória sucessional e dinâmica temporal, sem necessidade de futuras intervenções humanas. O objetivo desta tese foi avaliar os processos iniciais de restauração ecológica em áreas degradadas por mineração de carvão, através da análise de trajetórias sucessionais envolvendo: (1) taxas de crescimento e mortalidade de mudas nativas introduzidas e sua relação com atributos funcionais de plantas; (2) chuva de sementes associada, ou não, ao uso de poleiros artificiais e sua relação com regenerantes de espécies lenhosas; e (3) regeneração natural e sua relação com fatores abióticos e bióticos. Mudas de espécies nativas introduzidas sob condições limitantes (devido ao alto nível de impacto) apresentaram diferentes performances e relações com atributos, por vezes distintas do esperado para espécies sob condições naturais. A limitação de sementes nas áreas em restauração pode ser, potencialmente, reduzida pelo uso de poleiros artificiais, aumentando especialmente sementes de espécies não-pioneiras e zoocóricas. No entanto, não foi verificada relação entre a chuva de sementes e a taxa de recrutamento. Fatores abióticos, relacionados à composição química do solo, e fatores bióticos, como a presença de gramíneas exóticas, foram as variáveis com maior influência negativa sobre a regeneração natural. Este estudo evidencia a possibilidade do retornar do processo de sucessão natural em áreas de mata ciliar que foram profundamente alteradas por mineração de carvão, em um tempo relativamente curto. Entretanto, recomendamos o uso de objetivos realísticos e intermediários, bem como monitoramentos detalhados nas fases iniciais. / In current projects of ecological restoration, the return of ecosystem functions and natural processes is an important aim. However, many areas have lost their resilience due the high damage they have been submitted to, and this makes the ecological restoration a challenging process. For the success of the proposed activities, it is essential that during the project, the ecosystem can return to its successional trajectory without necessity of strong human intervention in the future. The goal of this thesis was to evaluate the initial processes of ecological restoration in areas severally degraded by coal mining, through analyses of successional trajectories regarding: (1) growth and mortality rates of planted samplings and their relationship to functional traits; (2) seed rain, associated or not, to perches and its relationship to natural regeneration of woody species; and (3) natural regeneration of woody species and its relationship to abiotic and biotic variables. Planted saplings under limited conditions (due the high impact of mining) showed to have distinct performance and trait relationships, somewhat different to the expected for species under natural conditions. The study indicates that the limitation of seeds in areas under ecological restoration can be reduced by the use of perches, increasing especially the number of seeds of non-pioneer and zoocoric species. Nevertheless, we did not found a relation between seed rain and recruitment rate. Soil chemistry (abiotic variable) and the cover of exotic grasses (biotic variable) were the variables with the strongest negative impact on natural regeneration. We conclude that it is possible to return to successional processes in areas of riparian forest severely damaged by coal mining activities in a relatively short time, but recommend the use of realistic, intermediate restoration goals and detailed monitoring in early restoration phases.

Holothuria scabra est l'holothurie comestible à haute valeur marchande la plus distribuée et la plus exploitée dans l'Indo-Pacifique tropical. Dès lors, et à cause de la demande croissante des pays importateurs et consommateurs, les stocks naturels de l'espèce sont confrontés actuellement un problème de surexploitation. A Madagascar, les situations économique, sociale et politique difficiles ainsi que l'insuffisance d'un plan efficace pour l'aménagement de cette exploitation, rendent la situation plus délicate encore. La surexploitation se traduit par la diminution de la production, la raréfaction de certaines espèces, la dégradation de la qualité du produit et entraîne une forte concurrence entre les exploitants et le non respect de la législation existante. Un plan d'aménagement de cette exploitation est proposé dans ce travail. Celui-ci concerne la gestion de la pêche, la restauration et la pérennisation des stocks naturels, et la valorisation des produits. L'holothuriculture est considérée comme la solution d'avenir pour pallier une demande sans cesse croissante en trépang, restaurer les stocks naturels et sauver les espèces d'holothuries menacées d'extinction. Dans ce travail, il s'agissait d'étudier les aspects biologiques de l'espèce liés à la réalisation de l'élevage de ses larves et juvéniles. Des études concernant le cycle de reproduction de la population locale (baie de Toliara 23° 27' S; 43°41' E côte Sud-ouest de Madagascar), l'induction de la maturation ovocytaire, le développement larvaire et post-larvaire, le développement squelettique chez les larves et les juvéniles, et la croissance des larves et des juvéniles ont été menées. Le but était d'optimaliser la production de juvéniles de H. scabra en écloserie en s'appuyant sur les connaissances préexistantes et acquises. Le cycle de reproduction de H. scabra a été étudié de novembre 1998 à avril 2001 par le suivi de la variation mensuelle de l'indice gonadique, de l'indice de maturité sexuelle et du pourcentage de chaque stade de maturité sexuelle. La population étudiée présente un cycle de reproduction annuel. Toutefois, des gonades mûres sont présentes dans la population presque toute l'année. Les individus mûrs et prêts à pondre sont toutefois plus nombreux entre novembre et avril. Le cycle annuel comporte cinq périodes mais la population étudiée n'a jamais présenté un cycle bien défini et stable. Les échantillons mensuels de gonades sont relativement hétérogènes. La gonade de Holothuria scabra est formée d'une touffe de plusieurs tubules ramifiés. Le développement des gonades ne suit pas le modèle de recrutement progressif des tubules. Si les tubules constitutif d'une gonade n'ont pas les mêmes longueurs, ils sont par contre au même stade de maturité sexuelle. La troisième partie du travail porte sur le développement et l'élevage de H. scabra en structures aquacoles et plus particulièrement sur la production des juvéniles. Ceci débute par l'obtention des œufs fécondés. Pour ce faire, une procédure artificielle recourant à l'induction de la maturation ovocytaire a été utilisée. L'utilisation d'une substance nouvelle (la Nirina) s'est avérée très efficace pour induire la maturation ovocytaire de l'espèce H. scabra. Plus de 90% des ovocytes deviennent matures et sont fécondables après avoir été mis en sa présence. Contrairement aux effets de diverses molécules connues pour induire la maturation chez certaines espèces (dithiothreitol, L-cysteine), les œufs fécondés obtenus par cette méthode sont viables et ont de développement normal. Le développement larvaire se fait en moyenne en deux semaines mais il est influencé par les facteurs température et densité d'élevage. Les élevages conduits à basse température et faible densité ont de meilleure performance de croissance et un meilleur taux de survie. Par contre, le développement est plus lent à basse température. La durée de la phase épibionte des juvéniles est évaluée à environ six semaines, période après laquelle les juvéniles atteignent une longueur moyenne de 20mm (0,5g). Leurs croissance et développement sont moins influencés par la température que ceux des larves. Leur croissance est influencée par la qualité de la nourriture. Les juvéniles épibiontes ont une croissance en longueur plus élevée (0,356 mm/j) et une croissance pondérale moins élevée (12,89mg/j) que les juvéniles fouisseurs (endobiontes). L'apparition et le développement des structures squelettiques ont été observé chez les larves et juvéniles de H. scabra. L'apparition des nouvelles spicules calcaires a pu être suivi chez les juvéniles épibiontes . Ce travail met en évidence de nouveaux aspects de la biologie et de l'élevage de H. scabra, espèce aux rôles économiques et écologiques importants dans les régions de l'Indo-Pacifique. La connaissance des aspects reproducteurs et du développementaux est essentielle pour une gestion durable des pêches et exploitation.

Ce travail de thèse focalise sur le fonctionnement du réseau microbien de la lagune de Thau à travers une approche « Réseau » ayant permis l’étude simultanée de l’ensemble des groupes microbiens (21 groupes) des virus au microzooplancton. La croissance et la mortalité des micro-organismes ont été étudiées expérimentalement lors de plusieurs saisons puis d’une étude en mésocosme. Nous avons déterminé les proportions de mortalité dont sont responsables le microzooplancton et les virus au travers de la lyse virale. Un suivi in situ puis en mésocosme dans la lagune de Thau nous a permis d'observer la réponse des composantes du réseau microbien à un forçage typiquement Méditerranéen, la crue.Il apparait que les bactéries hétérotrophes ont les plus fortes croissances allant jusqu’à 2,18 jour-1. La croissance pour divers groupes pico- et nano-phytoplanctoniques était inférieure à 1,5 jour-1. La cause majeure de mortalité des différents groupes de micro-organismes étudiés est la prédation du microzooplancton (> 90% en moyenne), tandis que la lyse virale semble être un processus sporadique et nettement moins important. Le fait que les taux de prédation observés soient très proches des taux de croissance de différents micro-organismes suggère que le réseau microbien étudié présente une forte efficacité de transfert de la biomasse vers les niveaux trophiques supérieurs.Dans ce contexte, la crue provoque à court terme une diminution de la croissance microbienne et du broutage, alors qu’elle déclenche la lyse virale chez certains groupes. Cependant, la réactivité de ce réseau permet un rétablissement rapide indiquant une forte capacité de résilience de ce système. / The aims of this thesis work were to shed new lights on the functioning of the microbial food web (MFW) in the Thau coastal lagoon through a “global approach” that permit us to study simultaneously the entire MFW components (21 groups) from viruses to microzooplankton. Growth and mortality of microorganisms were studied experimentally along seasons and during a mesocosm experiment. We particularly focus on mortality due to microzooplankton (<200µm) grazing and viral lysis. Responses of the different components of the MFW under a typical Mediterranean forcing, flash flood, was also studied during an in situ monitoring and a mesocosm experiment in the Thau Lagoon.In conclusion, it appears that heterotrophic bacteria show the highest growth rates (until 2.18 day-1). Growth rates of pico- and nanophytolankton groups were always lower than 1.5 day-1. The major cause of mortality of the different group studied, reaching on average 90%, was due to the predation by the microzooplankton. Mortality due to viral lysis appeared to be a “sporadic processes”, less important than microzooplankton grazing indeed. In addition, the observed grazing rates or bacterivory were close to growth rates of microorganisms, suggesting an efficient trophic transfer of the microbial biomass towards higher trophic levels.River flash flood; an important forcing in the Mediterranean coastal zone; triggered on a short time scale, a decrease in growth and grazing rates of microorganisms whereas viral lysis was enhanced. However, the important dynamics of this studied MFW allowed the rapid reestablishment of growth and grazing rates, indicating a strong resilience capability of this system.

Ziele Die Forsteinrichtung in Litauen war in den vergangenen Jahrzehnten vom Leitgedanken geprägt, die Optimierung der Bestandsdichte und die Maximierung der Produktivität in jeder Phase der Bestandsentwicklung als gleichrangige Ziele zu betrachten. Deshalb wurden große Anstrengungen in die Herleitung von Bestandswuchsmodellen für gleichaltrige Kiefern- oder Fichtenreinbestände gelegt. Bei der Anwendung dieser Modelle auf gemischte oder in der Umwandlung befindliche Wälder sind allerdings nur ungenaue Resultate zu erzielen. Um den Erfordernissen einer zeitgemäßen Forstwirtschaft gerecht zu werden, sind geeignete Instrumente zur Prognose von Wachstum und Ertrag strukturreicher Wälder vonnöten. Das Hauptziel dieser Arbeit bestand deshalb in der Neuparametrisierung des Einzelbaumwachstumssimulators BWINPro-S (entwickelt für sächsische Wuchsverhältnisse) für Kiefernwälder auf mineralischen Standorten in Litauen. Zur Zielerreichung dienten folgende Schritte: • Schaffung und Evaluierung einer Datengrundlage für die Modellierung. • Abschätzung der Effekte von Konkurrenz um Wuchsraum auf den Durchmesser-, Grundflächen- und Höhenzuwachs von Einzelbäumen. • Entwicklung eines Durchmesser-Zuwachsmodells sowie Neuparametrisierung der Grundflächen- und Höhenwachstumsmodelle. • Bestimmung der Einzelbaummortalität durch Konkurrenz um Wuchsraum. • Entwicklung eines ersten Ansatzes für einen Einzelbaumwachstumssimulator für Kiefer in Litauen. Hypothesen: 1. Die Standorteigenschaften sind der prägende Faktor für Wachstum und Ertrag von Waldbeständen. 2. Distanzabhängige Konkurrenzindizes zeigen höhere partielle Korrelationen zu Grundflächen- und Höhenzuwachs der Einzelbäume als distanzunabhängige Konkurrenzindizes. 3. Im Vergleich zum Ursprungsmodell BWINPro-S kann durch die Neuparametrisierung eine bessere Anpassung an die Wachstumswirklichkeit in Litauen erzielt werden (in Bezug auf Durchmesser-, Grundflächen- und Höhenzuwachs sowie Mortalitätsschätzung). 4. Ein Einzelbaumwachstumssimulator unterstützt die Entscheidungsträger und Forstplaner in Litauen bei der Optimierung der Waldbewirtschaftung ganz wesentlich. Material und Methoden Der Forschungsansatz gliederte sich wie folgt: 1) Vervollständigung der Datengrundlage. 2) Analyse der Konkurrenzverhältnisse. 3) Modellierung des Einzelbaumwachstums. 4) Validierung der neuentwickelten bzw. neuparametrisierten Modelle. Die Datengrundlage bestand aus Messwerten von 18 Dauerversuchsflächen (PEP) und zwei Validierungsflächen (VP), von denen letztere nur zur Modellüberprüfung herangezogen wurden. Auf allen Flächen stocken vorwiegend aus Naturverjüngung hervorgegangene, einschichtige Kiefernbestände auf kieferntypischen Standorteinheiten. Die Vervollständigung der Datengrundlage erforderte (a) die Erzeugung der Ausgangsdatenbasis, (b) Berechnung fehlender Werte, und (c) Evaluierung der vervollständigten Datengrundlage. Dabei lag das Hauptaugenmerk auf: • Stichprobenumfang und Schätzung der Populationsmittelwerte. • Schätzung des potentiellen Standort-Leistungsvermögens. • Analyse der Beziehung zwischen dem potentiellen Standort-Leistungsvermögen und dem tatsächlichen Waldertrag. Zur Abschätzung der Effekte von Konkurrenz um Wuchsraum auf den Durchmesser-, Grundflächen- und Höhenzuwachs von Einzelbäumen diente folgendes Vorgehen: Zur Konkurrentenidentifikation wurde ein inverser Lichtkegel mit einem Öffnungswinkel von 60 und 80 Grad konstruiert, dessen nach unten gerichtete Spitze (a) an der Kronenansatzhöhe, (b) an der Höhe der größten Kronenbreite, und (c) am Stammfuß des Zentralbaumes ansetzte. Zur Quantifizierung des Konkurrenzdrucks wurden mit Hilfe der partiellen Korrelationsanalyse 20 Konkurrenzindizes geprüft, von denen letztendlich sechs distanzabhängige und zwei distanzunabhängige Indizes in der weiteren Auswertung Berücksichtigung fanden. Die Modellierung des Einzelbaumwachstums erfolgte in drei Schritten: (a) Entwicklung eines originären Einzelbaum-Durchmesserzuwachsmodells, (b) Neuparametrisierung des Grundflächen- und Höhenzuwachsmodells, und (c) Entwicklung und Neuparametrisierung von Mortalitätsmodellen. Zur Bewertung einfacher linearer Regressionsmodelle wurden die statistische Signifikanz und das Bestimmtheitsmaß herangezogen. Bei multiplen linearen Regressionsmodellen wurde die Signifikanz jeder unabhängigen Variablen gesondert geprüft (hinsichtlich Normalverteilung, Varianzhomogenität der Residuen und Multikollinearität). Zur Bewertung einfacher nichtlinearer Regressionsmodelle diente in erster Linie das korrigierte Bestimmtheitsmaß, bei multiplen nichtlinearen Regressionsmodellen fanden darüber hinaus Q-Q-Plots (Quantil-Quantil-Diagramme) und die Prüfung auf Varianzhomogenität der Residuen Verwendung. Die Evaluierung multipler logistischer Regressionsmodelle erfolgte mit Pearsons Chi-Quadrat-Test, die Signifikanz jedes Modellparameters wurde mit der Wald-Statistik geprüft. Die Anpassungsgüte wurde mit Hilfe der Log-Likelihood-Funktion, Cox & Snell- bzw. Nagelkerke-Bestimmtheitsmaßen, Klassifikationstabellen und ROC-Kurven bewertet. Zur Prüfung der neuparametrisierten Grundflächen- und Höhenzuwachsmodelle wurden die modellierten Werte gegen die Messwerte und darüber hinaus die Residuen gegen die Modellwerte geplottet. Außerdem wurden zur Beurteilung die Verzerrung, die Präzision und die Treffgenauigkeit (sowohl als Absolut- als auch als Relativwerte) herangezogen. Ergebnisse und Schlussfolgerungen Die Wachstumsmodelle des Simulators BWINPro-S konnten erfolgreich an die Bedingungen in Litauen angepasst werden. Daraus lassen sich folgende Schlussfolgerungen ableiten: 1. Der stehende Vorrat und die Gesamtwuchsleistung von Kiefernbeständen werden nur z. T. vom standörtlichen Leistungsvermögen determiniert. Die Standorteigenschaften bestimmen das theoretische Leistungsvermögen von Beständen. Ob dieses Potential auch tatsächlich ausgeschöpft werden kann, hängt weitgehend von der Bewirtschaftungsart ab, die geprägt ist durch Beginn, Häufigkeit und Stärke der Durchforstungseingriffe. 2. In Kiefernreinbeständen eignen sich distanzabhängige Konkurrenzindizes besser zur Prognose des mittleren Grundflächenzuwachses als distanzunabhängige Indizes. Zur Beschreibung des Einzelbaum-Durchmesserzuwachses hat sich der Index nach BIGING & DOBBERTIN (1992, in dieser Arbeit als Index CI4 bezeichnet) in Kombination mit der Konkurrentenidentifikationsmethode „Suchkegelansatz in Kronenansatzhöhe, Öffnungswinkel 80 Grad“ als der bestgeeignetste Ansatz erweisen. 3. Der distanzunabhängige Konkurrenzindex nach HEGYI (1974) erreichte die höchsten partiellen Korrelationskoeffizienten mit den mittleren Einzelbaum-Höhenzuwächsen und ergab etwas bessere Resultate bei der Wachstumsprognose als distanzabhängige Indizes. Allerdings waren die Beziehungen zwischen den Konkurrenzindizes und den Einzelbaum-Höhenzuwächsen nur schwach ausgeprägt. 4. Konkurrenz wirkt sich dämpfend auf den Einzelbaum-Durchmesserzuwachs aus, bei zunehmender Konkurrenz sinkt der Zuwachs kontinuierlich ab. Im Gegensatz dazu beschleunigt leichte Konkurrenz das Einzelbaum-Höhenwachstum, bei starker Konkurrenz jedoch wird auch der Höhenzuwachs negativ beeinflusst. 5. Das im Rahmen dieser Arbeit hergeleitete nichtlineare Durchmesserzuwachsmodell ist zur Prognose des Kiefernwachstums bestens geeignet, das Bestimmtheitsmaß beträgt 0,483, die Residuen waren normalverteilt. 6. Die Neuparametrisierung des Grundflächen- und Höhenzuwachsmodells verbesserte die Anpassung an die Wuchsbedingungen in Litauen bedeutend. Eine erste Validierung, durchgeführt für eine Wachstumsprognose über einen 30-jährigen Zeitraum, ergab zufriedenstellende Ergebnisse. 7. Die zwei im Rahmen dieser Arbeit hergeleiteten Mortalitätsschätzer sind zur Vorhersage der natürlichen Absterbeprozesse in den Kiefernbeständen gut geeignet. Beide Ansätze klassifizierten lebende und tote Bäume mit einer Treffgenauigkeit von über 83%, während der in BWINPro-S enthaltene Schätzer nur 77% der Bäume korrekt zuordnete. 8. Der für litauische Verhältnisse neuparametrisierte Wachstumssimulator BWINPro-S ist ein wichtiges Instrument zur Entscheidungsunterstützung für Forstplaner in Litauen. / Objectives In Lithuania, during the most recent decades, the leading theory in forest management and planning combined optimization of forest stand density and maximal productivity at every time point of stand development. Thus, great effort was spent in creating stand level models that are highly effective in managing even-aged monocultures of pine or spruce forests. But these models produce significant errors in mixed or converted forests. In order to meet the requirements of contemporary forestry, appropriate forest management tools are required that would be capable to predict the growth and yield of more structured forests. Thus, the overall objective for this study was to re-parameterise the single tree level simulator BWINPro-S (developed for forests in Saxony/Germany) for Lithuanian pine forests that grow on mineral sites. To reach this goal, the following tasks were set: • To create, and to evaluate, a database for modelling. • To estimate the impact of competition for growing space on diameter, basal area and height growth of trees. • To develop a tree diameter model, and re-parameterise basal area and height growth models. • To assess natural tree mortality induced by competition between trees for growing space. • To develop the first approach of STLS for pine in Lithuania. Hypotheses 1. Site quality is the most important factor that affects forest growth and yield. 2. Distance dependent Competition Indices had higher partial correlation with tree basal area and height increment than distance independent Competition Indices. 3. The re-parameterised model based on Lithuanian data fits better under Lithuanian conditions (regarding diameter, basal area, height increment and mortality) than the original model BWINPro-S. 4. A single tree level simulator provides valuable support for decision makers and forest managers to improve forest management in Lithuania. Materials and methods To reach the main goals of this study, the research was structured to four sections: 1) Database completion, 2) Analysis of competition, 3) Modelling tree growth, 4) Validation of developed models. The database consisted of analytical data from 18 permanent experimental plots (PEPs) and 2 Validation Plots (VP) that were used only for the validation of the models. All plots (PEPs and VP) represent mainly naturally regenerated, single layer pine stands that grow on very typical pine sites. Database completion involved (a) establishment of the initial database, (b) modelling of missing data values and (c) evaluation of the complete database, which focused on: • Sample size and estimation of the population’s mean • Estimation of potential site productivity • Estimation of relationship between potential site productivity and forest yield In order to estimate the impact of competition for growing space on diameter, basal area and height growth of trees the following methods were used. To select the competitors, this study focuses on three separate positions for setting the inverse cone: a) at the height of the crown base, b) at the height of widest crown width, and c) at the stem base. The opening angle of the search cone was either 60 or 80 degrees. To estimate the competition, the study by partial correlation analysis evaluated a total of 20 competition indices, of which six distance dependent and two distance independent CIs were applied in the research programme. Modelling of tree growth was divided into three parts: a) development of an original tree diameter increment model, b) re-parameterisation of basal area and height increment models, and c) development of new natural mortality models and re-parameterisation of natural mortality models. Simple linear regression models were evaluated by estimating each model’s statistical significance and coefficient of determination. Statistical analysis of multiple linear regression models was enlarged by conducting further tests: statistical significance was checked for each independent variable: regression assumptions (concerning normal distribution and homogeneity of variance of the models’s residuals, and multicollinearity of the independent variables) were checked. Simple nonlinear regression models were evaluated mainly by adjusted coefficient of determination. For multiple nonlinear regression models, regression assumptions were also checked by producing normal Q-Q plots and by checking homogeneity of variance of model’s residuals. Multiple logistic regression models were evaluated by estimating each model’s statistical significance with Pearson’s chi square statistics and the statistical significance of each model’s parameters with Wald statistics. Goodness of fit was estimated by using log likelihood function values, Cox-Snell and Nagelkerkle’s coefficients of determination, classification tables and ROC curves. The re-parameterised basal area and height increment models were validated by plotting each model’s predicted values against observed values. Also each model’s residuals were plotted against predicted values. Bias, relative bias, precision, relative precision, accuracy and relative accuracy when comparing predicted and observed values were estimated as well. Results and Conclusions The growth models used in the BWINPro-S simulator were successfully re-parameterised for Lithuanian growth conditions. Thus the study may state these conclusions: 1. The accumulated standing volumes and overall productivity of pine stands only partially depends on the productivity potential of sites. Site quality defines the growth potential that could be reached in a stand. The realization of growth potential largely depends on the growing regime in the stand that is defined by the beginning, frequency and intensity of thinning. 2. In pure pine stands, distance dependent competition indices show greater capabilities to predict mean annual basal area increment than distance independent indices. Competition index (coded as CI4 in this study) proposed by BIGING & DOBBERTIN (1992) combined with the selection method height to crown base with opening angle of 80 degrees is recommended as the most efficient for describing the individual diameter growth of trees. 3. HEGYI\\\'S (1974) distance independent competition index scored the highest partial correlation coefficients and produced slightly better results than distance dependent competition indices in predicting mean annual height increment for individual trees. Yet, the generally poor performance of competition indices to predict height increment of individual pine trees was also recorded. 4. Competition has a purely negative impact on tree diameter growth. Increasing competition leads to steady decreases in diameter increment. Nevertheless, although a small amount of competition does stimulate tree height growth, stronger competition has a lasting negative impact on tree height growth. 5. The nonlinear diameter increment model, developed by this study, has high capabilities to predict growth of pine trees. The model’s coefficient of determination value was equal to 0.483. The distribution of the model’s residuals fulfilled the requirements of regression assumptions. 6. The re-parameterisation of the BWINPro-S basal area and height increment models for use in Lithuanian permanent experimental plots, increased their performance. During the first validation procedure, based on 30 years growth simulation, the re-parameterised models produced reliable results. 7. Two individual mortality models, developed by this study, showed very high capabilities to predict the natural mortality of pine trees. The distance dependent natural mortality model scored slightly better results. Both models managed to correctly classify dead and living trees, slightly more than 83% of the time. The re-parameterisation of the BWINPro-S natural mortality model increased its ability to predict the natural mortality of pine trees in Lithuania. Correctly classifying growing and dead trees increased by 6%, from 77 to 83%. 8. BWINPro-S simulator with re-parameterised growth models for Lithuanian conditions is a valuable support tool for decision makers and forest managers in Lithuania. / Darbo tikslai Lietuvoje ilgą laiką ūkininkavimas miškuose buvo grindžiamas medynų tankumo optimizavimu ir maksimalaus medynų produktyvumo siekimu visose medynų vystymosi stadijose. Mokslininkai dėjo daug pastangų kurdami medyno lygmens našumo modelius. Šie modeliai buvo patikimi ūkininkaujant vienaamžiuose medynuose. Tačiau jie yra sunkiai pritaikomi mišriuose medynuose. Siekiant patenkinti šiuolaikinio miškininkavimo poreikius, kai vis didesnis dėmesys skiriamas mišrių medynų su keliais ardais auginimui, reikalingi nauji modeliai, kurie sėkmingai prognozuotų mišrių medynų augimą, jų našumą bei reakcijas į įvairias ūkines priemones. Todėl pagrindinis šio darbo tikslas yra parametrizuoti iš naujo BWINPro-S medžio lygio stimuliatorių sukurtą Vokietijos rytinėje žemėje Saksonijoje taip pritaikant jį Lietuvos sąlygoms. Šiam tikslui pasiekti, buvo suformuluoti sekantys uždaviniai: • Paruošti ir įvertinti duomenų bazę reikalingą modeliavimui. • Įvertinti medžių tarpusavio konkurencijos įtaką medžių skersmens, skerspločių sumos ir aukščio prieaugiui. • Sukurti naują medžio skersmens prieaugio modelį ir parametrizuoti iš naujo skerspločių sumos bei aukščio modelius. • Įvertinti pušynų savaiminio retinimosi dėsningumus atsižvelgiant į medžių tarpusavio konkurenciją dėl augimo erdvės. Tikrintinos hipotezės: 1. Medyno augavietė yra svarbiausias veiksnys, lemiantis medynų našumą ir produktyvumą. 2. Konkurencijos indeksai, įvertinantys atstumą tarp medžių, turi didesnes dalinės koreliacijos reikšmes su medžių skerspločių sumos, skersmens ir aukščio prieaugiais lyginant su konkurencijos indeksais, neįvertinančiais atstumo tarp medžių. 3. Parametrizuoti naujai, panaudojant Lietuvoje augančių pušynų duomenis, modeliai geriau tinka Lietuvos sąlygoms (pagal skersmens, skerspločių sumos ir aukščio prieaugį bei savaiminį retinimąsi) lyginant su modeliais, sukurtais Vokietijos sąlygoms. 4. Medžio lygmens augimo simuliatorius yra naudinga priemonė miškų valdytojams siekiant pagerinti ūkininkavimo kokybę Lietuvoje. Darbo metodai Šis darbas buvo suskirstytas į keturias pagrindines dalis: 1) duomenų bazės suformavimas, 2) konkurencijos indeksų analizė, 3) medžių augimo modeliavimas, 4) augimo modelių patikrinimas. Duomenų bazę sudarė 20 pastovių tyrimo barelių, iš kurių 18 buvo skirti modelių kūrimui ir 2 modelių patikrinimui. Tyrimo bareliai buvo įsteigti natūraliai atsikūrusiuose vienaardžiuose pušynuose, augančiuose tipingose pušiai augavietėse. Duomenų bazės įvertinimas buvo atliekamas tokiais etapais: (a) pirminės duomenų bazės suformavimas, (b) trūkstamų matavimų modeliavimas ir (c) duomenų bazės įvertinimas yra grindžiamas: • Imties dydžiu ir populiacijos vidurkio nustatymo tikslumu. • Potencialaus medynų našumo įvertinimu. • Ryšių tarp potencialaus medynų našumo ir medynų našumo bei produktyvumo įvertinimu. Vertinant konkurencijos įtaką medžių skersmens, skerspločių sumos ir aukščio prieaugiui, buvo naudoti konkurentų parinkimo ir konkurencijos įvertinimo metodai. Konkuruojantys medžiai buvo atrenkami pagal apversto kūgio viršūnę, sutapatintą su tiriamojo medžio a) lajos pradžia, b) plačiausia lajos vieta, ir c) medžio šaknies kakleliu. Kūgio kampas buvo keičiamas nuo 60 iki 80 laipsnių. Iš viso buvo tiriama dvidešimt konkurencijos indeksų (du konkurencijos indeksai, nepriklausantys nuo atstumo tarp medžių ir aštuoniolika konkurencijos indeksų, priklausančių nuo atstumo tarp medžių). Konkurencijos indeksai vertinti taikant dalinės koreliacijos metodus. Medžių augimo modeliavimas buvo atliekamas trim etapais: a) originalaus medžių skersmens prieaugio modelio sukūrimas, b) medžių skerspločių sumos ir medžių aukščio prieaugio modelių parametrizavimas naujai, c) sukūrimas originalių ir parametrizavimas naujai jau esamų natūralaus retinimosi modelių. Paprastieji tiesinės regresijos modeliai buvo vertinami naudojant jų statistinį reikšmingumą ir skaičiuojant determinacijos koeficientą. Daugialypių tiesinės regresijos modelių statistinė analizė buvo išplėsta papildomais testais: statistinis reikšmingumas tiriamas kiekvienam nepriklausomam kintamajam, taip pat vertinama ar modelis tenkina pagrindines regresijos sąlygas (nepriklausomi kintamieji nėra tarpusavyje susieti, modelio liekanos turi normalųjį skirstinį, yra tolygiai išsidėstę). Paprastieji netiesinės regresijos modeliai buvo vertinami skaičiuojant koreguotąjį determinacijos koeficientą. Atliekant daugialypių netiesinės regresijos modelių analizę taip pat buvo tikrinama ar tenkinamos regresijos sąlygos. Logistiniai savaiminio retinimosi modeliai buvo vertinami naudojant šiuos statistinius parametrus: modelio X2 suderinamumo kriterijų, Voldo kriterijų, didžiausio tikėtinumo funkcijos vertę, Kokso-Snelo ir Nagelkerkės pseudodeterminacijos koeficientus, klasifikavimo lenteles ir klasifikatoriaus jautrumo ir specifiškumo (ROC) kreives. Parametrizuoti naujai medžių skerspločių sumos ir medžių aukščio prieaugių modeliai buvo tikrinami lyginant modeliuotas medžių skersmens ir aukščio reikšmes su realiai išmatuotomis reikšmėmis analizuojamo periodo pabaigoje. Taip pat buvo tiriamas modelių liekanų išsidėstymas modeliuojamų verčių atžvilgiu. Galiausiai, poslinkio, santykinio poslinkio, tikslumo, santykinio tikslumo, tikslumo be poslinkio ir santykinio tikslumo be poslinkio buvo naudojami vertinant modelių prognozes. Rezultatai ir išvados Augimo modeliai, naudojami BWINPro-S medžio lygio simuliatoriuje, buvo sėkmingai parametrizuoti naujai ir pritaikyti Lietuvos sąlygoms. Remiantis šio darbo rezultatais, buvo gautos sekančios išvados: 1. Sukauptas tūris ir bendras medynų našumas pušynuose tik dalinai priklauso nuo potencialaus augaviečių derlingumo. Augavietės sąlygos lemia tik potencialų medynų našumą kuris gali būti pasiektas medyne. Ar potencialus augavietės našumas bus realizuotas priklauso nuo medžių auginimo rėžimo, kuris apibūdinamas ugdomųjų kirtimų pradžia, kartojimų dažnumu ir jų intensyvumu. 2. Grynuose pušynuose, konkurencijos indeksai, įvertinantys atstumą tarp medžių turi didesnes galimybes prognozuoti skerspločių sumos prieaugį negu konkurencijos indeksai, neįvertinantys atstumo tarp medžių. Konkurencijos indeksas CI4, pasiūlytas BIGING & DOBBERTIN (1992), grindžiamas konkurentų parinkimu pagal apverstą 80 laipsnių kūgį, kurio viršūnė yra sutapatinama su medžių lajos pradžia yra rekomenduojamas kaip pats efektyviausias modeliuojant medžių skersmens prieaugį. 3. HEGYI (1974) konkurencijos indeksas, neįvertinantis atstumo tarp medžių tiriant konkurencijos indeksų įtaką medžių aukščio prieaugiui, parodė kiek geresnius dalinės koreliacijos rezultatus negu kad konkurencijos indeksai, įvertinantys atstumą tarp medžių. Tyrimų rezultatai parodė gana silpną konkurencijos indeksų galimybę prognozuoti medžių aukščio prieaugį. 4. Konkurencija turi išskirtinai neigiamą įtaką medžių skersmens prieaugiui. Didėjanti konkurencija lemia mažėjantį skersmens prieaugį. Nedidelė konkurencija padidina medžių aukščio prieaugį. Tačiau stipresnė konkurencija taip pat turi neigiamą įtaką medžių aukščio prieaugiui. 5. Originalus skersmens prieaugio modelis turi geras galimybes prognozuoti pušies medžių augimą. Šio modelio determinacijos koeficientas buvo lygus 0.483. Modelio liekanos turėjo normalųjį skirstinį ir buvo tolygiai pasiskirsčiusios modeliuojamų verčių atžvilgiu. 6. Parametrizuoti naujai BWINPro-S medžių skerspločių sumos ir medžių aukščio prieaugio modeliai, panaudojant Lietuvos pušynų pastovių tyrimo barelių duomenis, padidino jų prognozavimo galimybes. Pirmieji modelių tikrinimo rezultatai pagrįsti trisdešimties metų augimo prognozėmis, parodė, kad šie modeliai yra patikimi. 7. Du originaliai sukurti pušynų savaiminio retinimosi modeliai pasižymi geromis galimybėmis prognozuoti pušynų savaiminį išsiretinimą. Savaiminio retinimosi modelis, atsižvelgiantis į atstumą tarp medžių pasižymi geresnėmis galimybėmis prognozuoti pušynų savaiminį retinimąsi negu savaiminio retinimosi modelis, neatsižvelgiantis į atstumą tarp medžių. Abu modeliai teisingai klasifikavo daugiau negu 83% augančių ir savaime išsiretinančių medžių. BWINPro-S savaiminio retinimosi modelio parametrizavimas naujai padidino jo teisingai prognozuojamų augančių ir savaime išsiretinančių medžių dalį šešiais procentais, nuo 77 iki 83%. 8. Medžio lygio augimo simuliatorius BWINPro-S su parametrizuotais naujai augimo modeliais yra naudingas įrankis Lietuvos miškų augintojams.

Holothuria scabra est l'holothurie comestible à haute valeur marchande la plus distribuée et la plus exploitée dans l'Indo-Pacifique tropical. Dès lors, et à cause de la demande croissante des pays importateurs et consommateurs, les stocks naturels de l'espèce sont confrontés actuellement un problème de surexploitation. A Madagascar, les situations économique, sociale et politique difficiles ainsi que l'insuffisance d'un plan efficace pour l'aménagement de cette exploitation, rendent la situation plus délicate encore. La surexploitation se traduit par la diminution de la production, la raréfaction de certaines espèces, la dégradation de la qualité du produit et entraîne une forte concurrence entre les exploitants et le non respect de la législation existante. Un plan d'aménagement de cette exploitation est proposé dans ce travail. Celui-ci concerne la gestion de la pêche, la restauration et la pérennisation des stocks naturels, et la valorisation des produits. L'holothuriculture est considérée comme la solution d'avenir pour pallier une demande sans cesse croissante en trépang, restaurer les stocks naturels et sauver les espèces d'holothuries menacées d'extinction. <p>\ / Doctorat en sciences, Spécialisation biologie animale / info:eu-repo/semantics/nonPublished