The overall objective of the study was to analyse the Forest Dwelling Systems in the Terra Firme and Várzea communities and to investigate the conditions under which the different activities are allocated across households. In this study, the Farming System Approach facilitates a holistic examination of the Forest Dwelling Household System. This study broadly analyses the importance of natural products and their role as consumption and as goods for cash income for forest dwellers. By focusing on the functions of those products, their role within the Forest Dweller System must be examined. There have been identified differences between the Terra Firme (upland) and Várzea (floodplain) ecosystems management and production systems that are still ignored by decision makers. The study area was identified based on certain criteria: a) accessibility to the area (field support), b) availability of the forest production and, c) ecosystem (Terra Firme and Várzea communities). The survey was conducted in one community at the Terra Firme region (Itacoã) and in three communities at the Várzea region (Monte Tabor, Nova Santa Cruz, Manoel Carneiro). In selecting the households, the dependence on extraction of forest resources as the principal source of income was used as the major criteria, and part-time households were excluded from the studies. In order to obtain data on the structure of the entire Forest Dwelling Household System, productive activities within the house garden, cropping and forest extraction, financial and marketing aspects, were analyzed in 60 households (48 in Terra Firme and 12 in Várzea communities). Data concerning demography, socio-cultural aspects, labour force, land tenure were also gathered and analyzed. For this purpose households and key informants were interviewed with the use of a semi-structured questionnaire; participative observation was carried out and market research was executed. The households live basically to sustenance. A purely subsistence oriented family can only be identified as such if its production objectives are merely meant to fulfil subsistence needs. The type of forest dwelling household system existing in the region is strongly marked by small-scale production; the involvement of unpaid family workers in the production process; the combination of the incomes earned from on-, out- and off-farm activities and, to a limited extent, these households live under the threat of poverty. According to the results of the household financial analysis it could be stated that the main financial characteristics of households are the following: a) they are poor and have little ready cash; b) loans to them are usually unavailable; c) they are conscious of an uncertain environment, of cash shortage, and of household responsibilities and therefore are risk-averse; d) they often suffer cyclical labour shortage and under-employment; e) they are economically rational but not necessary profit maximising because they have their own scales of utility. The results of the analysis led to one priority goal, ranked as such by all the households, which was to satisfy the family?s sustenance, namely to supply sufficient food and provide housing for the family at all times. Only when food supply is guaranteed households will think of how to generate cash from their farm, in order to satisfy other needs which are part of an improved standard of living. Commercializing production does not come as a desire to maximize profit, but rather a need to generate cash income for subsistence purposes.

The global effort to rehabilitate and restore destroyed mangrove forests is unable to keep up with the high mangrove deforestation rates which exceed the average pace of global deforestation by three to five times. Our knowledge of the underlying processes of mangrove forest regeneration is too limited in order to find suitable techniques for the restoration of degraded mangrove areas. The general objective of my dissertation was to improve mangrove restoration by understanding regeneration processes and local plant-plant interaction in a regenerating Avicennia germinans forest. The study was conducted in a high-shore mangrove forest area on the Ajuruteua peninsula, State of Para, Northern Brazil. The dwarf forest consisting of shrub-like trees is recovering from a stand-replacing event caused by a road construction in 1974 which interrupted the tidal inundation of the study area. Consequently, infrequent inundation and high porewater salinity limit tree growth and canopy closure. All trees and seedlings were stem-mapped in six 20 m x 20 m plots which were located along a tree density gradient. Moreover, height, crown extent, basal stem diameter of trees were measured. The area of herbaceous ground vegetation and wood debris were mapped as well. The mapped spatial distribution of trees, seedlings and covariates was studied using point pattern analysis and point process models, such as Gibbs and Thomas point process, in order to infer underlying ecological processes, such as seed dispersal, seedling establishment, tree recruitment and tree interaction. In the first study (chapter 2), I analyzed the influence of abiotic and biotic factors on the seedling establishment and tree recruitment of A. germinans during the recolonization of severely degraded mangrove sites using point process modeling. Most seedlings established adjacent to adult trees especially under their crown cover. Moreover, seedling density was higher within patches of the herbaceous salt-marsh plants Blutaparon portulacoides and Sesuvium portulacastrum than in uncovered areas. The higher density of recruited A. germinans trees in herb patches indicated that ground vegetation did not negatively influence tree development of A. germinans. In addition, tree recruitment occurred in clusters. Coarse wood debris had no apparent effect on either life stage. These results confirm that salt-marsh vegetation acts as the starting point for mangrove recolonization and indicate that the positive interaction among trees accelerates forest regeneration. In the second study (chapter 3), I analyzed how intraspecific interaction among A. germinans trees determines their growth and size under harsh environmental conditions. Interaction among a higher number of neighboring trees was positively related to the development of a focal tree. However, tree height, internode length and basal stem diameter were only positively associated in low-density forest stands (1.2 trees m-2) and not in forest stands of higher tree density (2.7 trees m-2). These results indicated a shift from facilitation, i.e. a positive effect of tree interaction, towards a balance between facilitation and competition. In the third study (chapter 4), I used point process modeling and the individual-based model mesoFON to disentangle the impact of regeneration and interaction processes on the spatial distribution of seedlings and trees. In this infrequently inundated area, propagules of A. germinans are only dispersed at a maximum distance of 3 m from their parent tree. Furthermore, there is no evidence that the following seedling establishment is influenced by trees. I was able to differentiate positive and negative tree interactions simulated by the mangrove model mesoFON regardless of dispersal processes based on static tree size information using the mark-correlation function. The results of this dissertation suggest that mangrove forest regeneration in degraded areas is a result of facilitative and not competitive interactions among mangrove trees, seedling and herbaceous vegetation. This has important implications for the restoration of degraded mangrove forest. Degraded mangrove areas are usually restored by planting a high number of evenly spaced seedlings. However, high costs constrain this approach to small areas. Assisting natural regeneration could be a less costly alternative. Herbaceous vegetation plays a crucial role in forest recolonization by entrapping propagules and possibly ameliorating harsh environmental conditions. So far only competition among mangrove trees has been considered during restoration. However, facilitative tree interactions could be utilized by planting seedling clusters in order to assist natural regeneration instead of planting seedlings evenly-spaced over large areas. This dissertation also showed that point pattern analysis and point process modeling can enable forest ecologists to describe the spatial distribution of trees as well as to infer underlying ecological processes.

The tongtime deveolpment of 5 different forest stands with different harvest intensities had been monitored over 30 years. The appearance of secondary damages had been noticed. The results of monitoring had been used for a simulation of the future development. / Holzernteschäden unterschiedlicher Holzernteintenistäten wurden untersucht und in einem Zeitraum von bis zu 30 Jahren beobachtet. Dabei wurde besonders dem Auftreten von Sekundärschäden wie Sonnenbrand und Wasserreiser Beachtung geschenkt. Die gewonnenen Informationen wurden genutzt, um die zukünftige Bestandesentwicklung zu simulieren.

Die vorliegende Studie analysiert die Politische Ökonomie von Forstplantagen in den Tropen. Die Analyse der Makroebene zeigt dabei eine globale Perspektive auf, sowie historische Veränderungen von Paradigmen in Bezug zu Waldplantagen. Der zweite Teil der Studie analysierte Plantagen auf der Mikro-Ebene im Hinblick auf divergente geographischen Zusammenhänge, nämlich Paraguay und Indonesien. Fallstudien eignen sich hierbei, um ein vielfältiges Spektrum von Waldplantagen darzustellen, sowie Beispiele für die in der Makroebene abgeleiteten Paradigmen zu illustrieren. Abschließend verbindet die Studie die Entwicklungen der Makro-Ebene mit Belegen aus der Mikro-Analyse. Hierauf ableitend werden Empfehlungen für die Anlage zukünftiger Plantagen getätigt. Die Methodik wurde den Untersuchungsebenen in einem iterativen Prozess angepasst. Der Umfang variiert dabei von Makro- bis Mikroanalysen, sowie vom theoretischen bis zum empirischen Niveau. Auf der Makroebene wurde eine Politische-Ökonomie-Analyse und eine Untersuchung desrelevanten historischen Materials durchgeführt. Weiterhin wurden Plantagen Paradigmen anhand ausgewählter Indikatoren abgegrenzt. Für die Mikroebene wurden Fallstudien mit lokalen Interviews durchgeführt, welche Daten für eine Mehrkriterienanalyse (MCA) lieferten. Die Kombination der Mikro- und Makroanalyse erfolgte durch eine Korrelationsanalyse und wurde durch eine Diskussion abgerundet. Das Forschungsergebnis aus der globalen Analyse ist eine Typologie von sechs Paradigmen und deren Untervarianten, welche als theoretisches und analytisches Werkzeug in der Forschung zu Plantagen dienen können. Die Paradigmen wurden klassifiziert als: i) das vorindustrielle P.; ii) das kolonial industrielle und national industrielle; iii) das Schutzparadigma; iv) das soziale P.; v) das neo-liberale und modifiziert neoliberale P. und vi) das globalpolitische Paradigma. Die Ergebnisse der Fallstudien und MCA zeigen zum einen sichtbare Mängel in Plantagen unter verschiedenen Paradigmen auf und unterstreichen zum anderen positive Effekte bestimmter Paradigmen. Die MCA Bewertungspunkte zeigen zum Beispiel, dass manche Paradigmen mit dem Kriterium Landkonflikt korrelieren, oder präsentieren unterschiedliche lokale Beteiligung auf verschiedenen Plantagen, illustrieren Vorteile, die Plantagen für unterschiedliche Interessengruppen bringen. Die MCA bewertet weiter die Wirtschaftsleistung der Plantagen und vergleicht Faktoren, wie Nutzenverteilung, Rentabilität, Marktzugang und Rahmenbedingungen für Investitionen. Sie analysiert soziale Faktoren, wie Arbeitssicherheit, Zugang zu Dienstleistungen, Beteiligung oder Personalmanagement. Weiterhin werden Umweltprobleme durch die Studie aufgegriffen, z.B. Landnutzungsänderungen, Wasser- oder Boden- Auswirkungen, Lebensraumfunktion usw. Wie die vergleichende Analyse zeigt, ist die modifizierte Neoliberale Paradigma Plantage (Outgrower-Scheme) besonders geeignet, um sowohl soziale als auch wirtschaftliche Vorteile zu sichern (90 % und 84 % in den entsprechenden Feldern gegenüber dem hypothetischen Idealtyp Plantage). Andere Forschungsergebnisse deuten auf wichtige Erkenntnisse bei der Plantagenentwicklung hin, die auf der Plantagen-Ebene und bei der Gestaltung nationaler Rahmenbedingungen für den Plantagensektor berücksichtigt werden sollten. Handlungsempfehlungen für die forstwirtschaftliche, epistemische Gemeinschaft zur Gestaltung der weiteren Diskurse in Bezug auf globalen Plantagen werden ebenfalls diskutiert.