Open Access

Forest ecosystems are complex systems that develop inherent structures and processes relevant for their functioning and the provisioning of ecosystem services that contribute to human wellbeing. So far, forest management focused on timber production while other services were less rewarded. With increasing climate change impacts, especially regulating ecosystem services such as microclimate regulation are ever more relevant to maintain forest functions and services. A key question is how forest management supports or undermines the ecosystems’ capacity to maintain those functions and services. Forest management implies silvicultural interventions such as thinning and timber harvesting and ranges from single tree extraction to large clearcuts as well as forest reserves without active forest operations and shape the character of forest ecosystems (e.g. natural versus planted forests). Artificial plantings, monocultures and management for economic timber production simplify forest structures and impair ecosystem resilience, resistance and the existence of forests but also the services essential for the prosperity and health of humanity. Efforts to reduce the negative impacts and attempts to safeguard forest functions are manifold and include compulsory national and international guidelines and regulations for forest management, conventions, but also voluntary mechanisms such as certification systems. The main objective of this thesis was the development of a concept to assess the functionality of forests and to evaluate the effectiveness of forest ecosystem management including certification. An ecosystem-based and participatory methodology, named ECOSEFFECT, was developed. The method comprises a theoretical and an empirical plausibility analysis. It was applied to the Russian National FSC Standard in the Arkhangelsk Region of the Russian Federation – where boreal forests are exploited to meet Europe's demand for timber. In addition, the influence of forestry interventions on temperature regulation in Scots pine and European beech forests in Germany was assessed during two extreme hot and dry years in 2018 and 2019. Microclimate regulation is a suitable proxy for forest functionality and can be applied easily to evaluate the effectiveness of forest management in safeguarding regulating forest functions relevant under climate change. Microclimate represents the most decisive factor differentiating clearcuts and primary forests. Thus, the assessment of forest microclimate regulation serves as convenient tool to illustrate forest functionality. In the boreal and temperate forests studied in the frame of this thesis, timber harvesting reduced the capacity to self-regulate forests’ microclimate and thus impair a crucial part of ecosystem functionality. Changes in structural forest characteristics influenced by forest management and silviculture significantly affect microclimatic conditions and therefore forest ecosystems’ vulnerability to climate change. Canopy coverage and the number of cut trees were most relevant for cooling maximum summer temperature in pine and beech forests in northern Germany. Maximum temperature measured at ground level increased by 0.21 – 0.34 K when 100 trees were cut. Opening the forest canopy by 10 % caused an increase of maximum temperature at ground-level by 0.53 K (including pine and beech stands). Relative temperature cooling capacity decreased with increasing wood harvest activities and dropped below average values when more than 656 trees per hectare (in 2018; and 867 trees in 2019) were felled. In pine stands with a canopy cover below 82 % the relative temperature buffering capacity was lower than the average. Mean maximum temperature measured at ground-level and in 1.3 m was highest in a pine-dominated sample plots with relatively low stand volume (177 m3 ha-1) and 9 K lower in a sample plot with relatively high stock volumes of F. sylvatica (> 565 m3 ha-1). During the hottest day in 2019, the difference in temperature peaks was more than 13 K for pine-dominated sample plots with relatively dense (72 %) and low (46 %) canopy cover. The Russian FSC standard has the potential to improve forest management and ecological outcomes, but there are shortcomings in the precision of targeting actual problems and ecological commitment. In theory, FSC would transform forest management practices and induce positive changes and effective outcomes by addressing 75 % of the identified contributing factors including highly relevant factors and threats including large-scale (temporary) tree cover loss, which contributes to reducing about half of the identified stresses in the ecosystem. It is theoretically plausible that FSC prevents logging in high conservation value forests and intact forest landscapes, reduces the size and number of clearcuts, and prevents hydrological changes in the landscape. However, the standard was not sufficiently explicit and compulsory to generate a strong and positive influence on the identified problems and their drivers. Moreover, spatial data revealed, that the typical regular clearcut patterns of conventional timber harvesting continue to progress into the FSC-certified boreal forests, also if declared as ‘Intact Forest Landscape’. This results in the need to verify the assumptions and postulates on the ground as it remains unclear and questionable if functions and services of boreal forests are maintained when FSC-certified clearcutting continues. On the clearcuts, maximum temperature exceeded 36 °C and stayed below 30 °C in the closed primary forest. The number of days with temperatures above 25 °C at least doubled on clearcuts. Temperature cooling capacity was reduced by up to 14 % and temperature buffering capacity up to 60 %. The main reason why FSC-certified clearcuts do not differ from conventional clearcuts is that about 97 % of trees within equally large clearcut sites of up to 50 ha were removed. The spatial design of clearcuts, their size and the intensity of clearing as well as the density of skidding trails for timber extraction was not positively influenced by FSC-certification. Annual tree cover loss was lowest in non-certified areas. This means, that FSC may even contribute to an increased biomass removal within the clearcuts, which compromises the ecosystems’ capacity to recover and maintain ecological functions and services. The analysis of satellite-based data on tree cover loss showed that clearcutting causes secondary dieback in the surrounding of the cleared area. FSC-certification does not prevent the various negative impacts of clearcutting and thus fails to safeguard ecosystem functions. The postulated success in reducing identified environmental threats and stresses, e. g. through a smaller size of clearcuts, could not be verified on site. The empirical assessment does not support the hypothesis of effective improvements in the ecosystem. In practice, FSC-certification did not contribute to change clearcutting practices sufficiently to effectively improve the ecological performance. Sustainability standards that are unable to translate principles into effective outcomes fail in meeting the intended objectives of safeguarding ecosystem functioning. Clearcuts that carry sustainability labels are ecologically problematic and ineffective for the intended purpose of ecological sustainability. The overexploitation of provisioning services, i.e. timber extraction, diminishes the ecosystems’ capacity to maintain other services of global significance. It also impairs ecosystem functions relevant to cope with and adapt to other stresses and disturbances that are rapidly increasing under climate change. Forest management under climate change needs to apply precautionary principles and reduce further ecological risks such as secondary dieback and deterioration of regulating services that are relevant for the functioning of forests. Forest managers have to avoid ecological disimprovements by applying strict ecological principles with effective outcomes in order to maintain functional forests that regulate their own microclimate also as a basis for sustainable economic benefits.

"Sustainable development: enough for everyone, forever" is the definition of sustainability. Sustainable landscape development is the main goal of decision makers worldwide. Achieving this goal in the long term leads to achieving social, economic and environmental sustainability. Remote sensing has been playing an essential role in monitoring remote areas. This study has employed part of the role of remote sensing in supporting the direction of decision makers towards sustainable landscape development. The study has focused on some of the main elements affecting sustainable environment as stated in Agenda 21. These elements are land uses, specifically agricultural land uses, water quality, forests, and water hazards such as floods. Three research programs were undertaken to investigate the role of Terrasar-x imagery, as a source of remote sensing data, in monitoring the environment and achieving the previous stated elements. The investigation was intended to investigate the effectiveness of TSX imagery in identifying the cropping pattern of selected study areas by employing a pixel-based supervised maximum likelihood classifier, as published in Paper I, assessment of the efficiency of using TSX imagery in determining land use and the flood risk maps by applying an object-based decision tree classifier as published in Paper II, and determination of the potential of inferential statistics tests such as the two samples Z-test and multivariate analysis, for example Factor Analysis, for identifying the kind of forest canopy, based on the backscattering coefficient of TSX imagery of forest plots, as presented in Paper III. Papers I and II covered two pilot areas in the Lower Saxonian Elbe Valley Biosphere Reserve “das Biosphärenreservat „Niedersächsische Elbtalaue„ around Walmsburger Werder between Elbe-Kilometer 533 - 543 and Wehninger Werder between Elbe-Kilometer 505 - 520. Paper III focused on the Fuhrberger Feld water protection area near Hanover in Germany. The inputs for this research were mainly SAR Imagery and the ground truth data collected from field surveys, in addition to databases, geo-databases and maps. The study presented in Paper I used two filters to decrease speckle noise namely De-Grandi as multi-temporal speckle filter, and Lee as an adaptive filter. A multi-temporal classification method was used to identify the different crops using a pixel-based maximum likelihood classifier. The classification accuracy was assessed based on the external user accuracy for each crop, the external producer accuracy for each crop, the Kappa index and the external total accuracy for the entire classification. Three cropping pattern maps were produced namely the cropping pattern map of Wehninger Werder in 2011 and the cropping pattern maps of Walmsburger Werder in 2010 and in 2011. The study showed that image filtering was essential for enhancing the accuracy of crop classification. The multi-temporal filter De-Grandi enhanced the producer accuracy by about 10% compared to the Lee filter. Furthermore, gathering and utilizing large ground truth data greatly enhanced the accuracy of the classification. The research verified that using sequence images covering the growing season usually improved the classification results. The results exposed the effect of the polarization, where using VV-polarized data enabled on average 5% higher classification accuracy than the HH-polarized data, however using dual polarized data enhanced the classification accuracy by 3%. The study demonstrated that the majority of the classifications produced according to the crop calendar had higher total producer accuracy than using all acquisitions. The study demonstrated undertaken in Paper II applied the decision tree object-based classifier in determining the major land uses and the inundation extent areas in 2011 and 2013 using the Lee-filtered imagery. Based on the maps produced for the land uses and inundation areas, the hazard areas due to the floods in 2011 and 2013 were identified. The study illustrated that 95% of the inundated area was classified correctly, that 90% of vegetated lands were accurately determined, and around 80% of the forest and the residential areas were correctly recognized. The study demonstrated that the residential areas did not experience any hazards in both pilot areas, however some cultivated lands were fully or partially submerged in 2011. These fields are in the high flood zone and therefore are expected to be entirely submerged during future high floods. Although, these fields were flooded in January 2011, they were cultivated with maize and potatoes in summer 2011 and in subsequent years and consequently were inundated in June 2013 with high economic losses to the owners of these fields. The research undertaken in Paper III statistically analyzed the backscattering coefficient of the Lee-filtered TSX in some forest plots by the Factor Analysis and two sample Z-test. The study showed that Factor analysis tools succeeded in differentiating between the coniferous forest and the deciduous forest and mixed forest, but failed to discriminate between the deciduous and the mixed forest. On one hand, only one factor was extracted for each sample plot of the coniferous forest with approximately equal loadings during the whole acquisition period from March 2008 to January 2009. On the other hand, two factors were extracted for each deciduous or mixed forest sample plot, where one factor had high loadings during the leaf-on period from May to October, and the other one had high loadings during the leaf-off period from November to April. Furthermore, the research revealed that the two sample Z-test enabled not only differentiation between the deciduous and the mixed forest against the coniferous forest, but also discrimination between deciduous forest and the mixed forest. Statistically significant differences were observed between the mean backscatter values of the HH-polarized acquisitions for the deciduous forest and the mixed forest during the leaf-off period, but no statistically significant difference was found during the leaf-on period. Moreover, plot samples for the deciduous forest had slightly higher mean backscattering coefficients than those for the mixed forest during the leaf-off period.

Tropical forests worldwide support high biodiversity and contribute to the sustenance of local people’s livelihoods. However, the conservation and sustainability of these forests are threatened by land-use changes and a rapidly increasing human population. In this dissertation, I focused on the effects of land-use change on forest biodiversity in the rural landscapes of southwestern Ethiopia, against a backdrop of human population growth. These landscapes are being progressively degraded, encroached and fragmented as a result of different pressures, including the intensification of coffee production, farmland expansion, urbanization and a growing rural population. Understanding the drivers of biodiversity loss and the responses of biodiversity to such pressures is fundamental to direct conservation efforts in these tropical forests. This dissertation aimed to characterize biodiversity patterns in the moist Afromontane forests of southwestern Ethiopia and to examine how biodiversity patterns are affected by land-use and land-use changes (mediated by coffee management intensity, landscape attributes and housing development) in a context of a rapidly growing rural population. To achieve this goal, I take an interdisciplinary approach where, first, I examined the effects of coffee management intensity on diversity patterns of woody plants and birds, spanning a gradient of site-level disturbance from nearly undisturbed forest interior to highly managed shade coffee forests. Results showed that specialized species of woody plants (forest specialists) and birds (forest specialists, insectivores and frugivores) were affected by coffee management intensity. The richness of forest specialist trees and the richness and/or abundance of insectivores, frugivores and forest specialist birds decrease with increasing levels of disturbance. Second, I investigated the effects of landscape context on woody plants, birds and mammals. Community composition and specialist species of woody plants and birds were sensitive to landscape context, where woody plants responded positively to gradients of edge-interior and birds to gradients of edge-interior and forest cover. Further results showed that a diverse mammal community, with 26 species, occurs at the forest edge of shade coffee forests and that the leopard, an apex predator in the region depended on large areas of natural forest. A closer examination of leopard activity patterns revealed a shift in the diel activity as a response to human disturbance inside the forest, further highlighting the importance of natural undisturbed forests for leopards in the region. Together, these findings demonstrate the value of low managed shade coffee forests for biodiversity, and importantly, emphasize the irreplaceable value of undisturbed natural forests for biodiversity. Third, I investigated the effects of prospective rural population growth (mediated by housing development) on the forest mammal community. Here, population growth was projected to negatively influence several mammal species, including the leopard. Housing development that encroached the forest entailed worse outcomes for biodiversity than a combination of prioritized development in already developed areas and coffee forest protection. Fourth, to understand the motivations behind high human fertility rates in the region, I examined the determinants of women fertility preferences, including their perceptions on social and biophysical stressors affecting local livelihoods such as food insecurity and environmental degradation. Fertility preferences were influenced by underlying social norms and mindsets, a perceived utilitarian value of children and male dominance within the household, and were only marginally affected by perceptions of social and biophysical stressors. Results further indicated a mismatch between the global discourse on the population-environment-food nexus and local perceptions of this issue by women. My findings suggest the need for new deliberative and culturally sensitive approaches that engage with pervasive social norms to slow down population growth. Overall, this dissertation demonstrates the key value of moist Afromontane forests in southwestern Ethiopia for biodiversity conservation. It indicates the need to promote coffee management practices that reduce forest degradation and highlights that high priority should be given to the conservation of undisturbed natural forests. It also suggests the need to integrate conservation goals with housing development in landscape planning. A promising approach to achieve the above conservation priorities would be the creation of a Biosphere Reserve and to promote the ecological connectivity between the larger forest remnants in the region. Finally, this dissertation demonstrates the importance of placed-based holistic approaches in conservation that consider both proximate and distal drivers of forest biodiversity decline.    

Die Kulturlandschaft im Alpenraum war in den letzte Jahrzehnten einem besonders starken Strukturwandel ausgesetzt. Als Region mit einem hohen Anteil an Grenzertragsstandorten lassen sich hier zwei gegenläufige Entwicklungen feststellen: zum einen findet eine Intensivierung der Landnutzung in Bereichen mit guter Zugänglichkeit und maschineller Nutzbarkeit statt, zum anderen kommt es häufig zu einem Rückgang der Nutzungsintensität oder Nutzungsaufgabe in Bereichen, in denen die landwirtschaftliche Bearbeitung schwierig ist. Die Auswirkungen auf die Biodiversität werden bei beiden Entwicklungen kritisch gesehen, allerdings mangelt es an detaillierten Untersuchungen. Im Rahmen eines sechsjährigen Forschungsvorhabens wurden auf einer Weidefläche in den Allgäuer Alpen Laufkäfer, Spinnen und Vegetation untersucht. Auf der Fläche fand zu Beginn der Untersuchung eine Nutzungsänderung statt: ein großer Teil der vormals intensiv von Schafen beweideten Fläche wurde auf extensive Rinderbeweidung umgestellt, kleine Teilflächen wurden aus der Nutzung genommen. Der Fokus dieser Dissertation liegt in den Untersuchungen der Laufkäfer. Hier wurde zunächst ein Erfassungsschema für Laufkäfer in schwer erreichbaren Gebieten der Alpen erarbeitet, um intensive und mehrjährige Untersuchungen logistisch durchführen zu können. Dabei wurden die Ergebnisse der Laufkäfererfassung über die gesamte Vegetationsperiode mit den Ergebnissen einer reduzierten Erhebung verglichen. Es konnte gezeigt werden, dass eine Beprobung über jeweils zwei Wochen Anfang Juni und Anfang Juli den gesamten Datensatz hinreichend repräsentiert. Des weiteren wurde untersucht, ob die Vegetation als Surrogat für die beiden untersuchten Arthropodengruppen (Spinnentiere und Laufkäfer) dienen kann, d.h. die Ergebnisse der Vegetation auf die anderen Artengruppen übertragbar ist. Dies wurde sowohl auf Ebene der Artzusammensetzung als auch des Artenreichtums für die drei Taxa geprüft. Zudem wurde überprüft, ob die unter vegetationskundlichen Aspekten abgegrenzten geschützten Lebensraumtypen auch besonders wertvolle Habitate für die Arthropodengruppen darstellen. Die Ergebnisse der Untersuchung zeigen, dass eine ausreichende Kongruenz nicht gegeben und damit die Übertragbarkeit von Ergebnissen bei der Vegetation auf die untersuchten Arthropodengruppen in den Gebirgslebensräumen nicht gewährleistet ist. Dies hat eine hohe praktische Relevanz, da im Rahmen von Managementplanungen für die FFH-Richtlinie als auch bei der Bayerischen Alpenbiotopkartierung überwiegend ein starker Fokus auf vegetationskundlichen Aspekten liegt und insbesondere artenreiche Arthropodengruppen meist nicht betrachtet werden. Abschließend wurde mittels gemischter Modelle (mixed effects models) untersucht, welche Veränderungen bei den Laufkäfern nach der Nutzungsänderung im Untersuchugnsgebiet auftraten. Sämtliche errechneten Modelle zeigten Veränderungen der abhängigen Variablen über die Zeit: nach Aufgabe der intensiven Schafbeweidung nahmen die Arten- und Individuenzahlen sowie die Biomasse an Laufkäfern zu. Die Tiere wurden durchschnittlich größer und es traten mehr herbivore Laufkäfer auf. Auch konnten unterschiedliche Entwicklungen zwischen den Standorten beobachtet werden. Die beobachteten Veränderungen werden im Artikel detailliert diskutiert. Die meisten Veränderungen, insbesondere die Zunahme der Artenzahlen sowie der durchschnittlichen Körpergröße, deuten auf eine Erholung der Laufkäferfauna von der intensiven Schafbeweidung hin. Die Nutzungsumstellung und die aktuell praktizierte extensive Rinderbeweidung werden im Gebiet naturschutzfachlich positiv bewertet. Die Arbeit liefert eine gute Vorlage und fundierte Begründung, gerade auch im Alpenraum verstärkt Laufkäfer bei der Beantwortung naturschutzfachlicher Fragestellungen einzubinden.

We are in a phase of an alarming biodiversity loss, by scientist already referred to as Earth’s sixth mass extinction. According to estimations, the current extinction rates are 100 to 1000 times higher than those predicted from fossil records. To counteract species loss and preserve the remaining biodiversity, with its important ecosystem functioning and services essential to human well-being, there is an urgent need to develop promising and long-term conservation strategies. In order to achieve these goals, extensive research to gain a better understanding of the general mechanisms underlying community diversity is of greatest importance. Especially, the identification of intrinsic ecological and distributional species traits is receiving increased attention in ecology and conservation biology research. Depending on the expression of their traits, species perform particular ecosystem functions and respond in a specific manner to environmental conditions. The identification of the effect of certain traits on community compositions can therefore significantly improve our understanding of species extinction processes and help to develop valuable and appropriate recommendations for conservation management. As trait-based analyses are applicable to different geographical, temporal and taxonomical scales, they may even allow for a broader generalization if similar results are found on different scales, i.e. for local species pools, the complete species pools of different habitat types or the entire species pool across several habitat types including different climatic regions. Although insects make up the largest part of animal diversity and provide essential ecosystem services in form of e.g. pollination, pest control, and decomposition, the majority of studies on extinctions have mainly focused on vertebrates. Among invertebrates either charismatic taxa or those targeted by conservation laws have been investigated until now (e.g. butterflies or saproxylic beetles). Being highly species-rich and trait-diverse, ground beetles (Coleoptera: Carabidae) should be even more suitable for conducting trait-based analyses. Thus, using ground beetles as a model taxon, four case studies focusing on the analyses of traits form the basis of this doctoral thesis. The work of this thesis was conducted with the aim of gaining general insights on the influence of species traits on ground beetle community compositions, such as habitat occupancy and species vulnerability to extinction, for instance. An important aspect when investigating species traits is the consideration of confounding factors which could influence the results, such as dependent relations between the different traits. Compiling a large dataset of 566 Central European species, I identified that dependent relations between the six tested traits of ground beetles (distribution range size, habitat specialization, body size, hind-wing morphology, breeding season and trophic level) are highly common. Across all identified dependent trait relations, the relation between body size and hind wing morphology or range size and hind wing morphology showed the strongest significant dependencies. Since the consideration of trait relations is necessary to provide reliable interpretations, all analyses of this thesis tested several traits simultaneously and considered possible trait interactions. Studies on local communities found specific traits characterizing the local species pools of certain habitat types. Here, the species pools of seven different habitat types (coastal, forest, mountain, open, riparian, wetland and special habitat) were used to determine habitat-specific trait filters. The identified traits, characteristic for certain habitat types, were in most cases in accordance with the previous findings on local communities. Across Germany, the species of frequently disturbed habitat types, namely coastal, riparian and wetland habitats were characterized by small body size, high amount of macroptery, intermediate to high habitat specialization, spring breeding, and predatory feeding behavior. The species of stable habitat types (forest, mountain, and open habitats), however, were found to be generally larger in body size and more frequently breeding in autumn, further displaying greater variations in the other traits. The gained knowledge on the habitat-specific filtering of traits improve our understanding of the organization and assembly of communities, and can thereby help to detect alterations in the habitat-specific species pool due to natural or human-induced environmental changes. Furthermore, traits can provide evidence on species occurrences and vulnerability to extinction. Three case studies of this thesis aimed to gain new insights on this topic, through the investigations on the following research questions; I. Which traits drive species extinction risks of Central European ground beetle species, II. How traits influence the species occurrences of 28 forest species within a large area in Central Europe, and III. Whether certain traits are related to long-term population trends of the species pool from an ancient forest in northern Germany. The results indicated, that depending on the habitat type and tested species pool, different traits prove to be good predictors for the vulnerability of species. Nevertheless, across different geographical and taxonomical scales, especially species with small range sizes and high habitat specialization faced a greater risk of extinction. Therefore, the two traits distributional range size and habitat specialization emerge as reliable predictors of ground beetles vulnerability to extinction. Interestingly, body size did not display a consistent response; while increasing body size led to higher extinction risk in riparian, wetland and open habitats and large macropterous species showed higher extinction risks across the entire species pool, smaller species showed long-term population declines in an ancient forest. To summarize, this thesis presents a comprehensive picture of ground beetle species traits, providing valuable insights and a better understanding of the mechanisms driving changes in ground beetle diversity. On the basis of the results presented in this work, the efficiency of biodiversity protection can be increased by developing appropriate management and recovery plans, especially targeting species of threatened habitat types or ‘functional groups’ of species, exhibiting trait values strongly associated with a greater vulnerability to extinction.