A prey animal can use different strategies to avoid becoming eaten by predators. One such widely recognised strategy is the use of body colouration to decrease the risk of becoming detected, i.e. cryptic colouration. The principles of crypsis that I have studied are background matching, disruptive colouration and distractive markings. Further, I also studied the concealing effect of the visual background habitats. I used artificial prey items and backgrounds, and blue tits (Cyanistes caeruleus) as predators, to investigate prey concealment. In Paper I, I tested if high-contrast markings in prey coloration or in the background would result in a distracting effect. I found that such markings did increase prey search time, even when the prey markings were lighter or darker than the background. In Paper II, I studied the use of chromatic cues by predators when searching for prey. The birds easily detected prey that chromatically deviated from its background. Interestingly, background-matching prey was more difficult to detect when the colour scheme had low ultraviolet and high shortwave reflectance compared to when the reflectance bands were even. In Paper III, I studied optimisation of achromatic contrast within prey colour pattern and also the effect of shape diversity of background pattern elements on prey detection. I found that all prey types were more difficult to detect on the diverse background, but the level of contrast within prey pattern did not influence search times. In Paper IV, I further investigated how a prey should optimise its patterning with respect to background matching. I found that prey with repeated pattern elements was equally hard to detect as prey with more variable pattern. However, prey with a spatially regular pattern (aligned pattern elements) was easier to detect than prey with a spatially irregular pattern. In this paper I also found that high complexity of element shapes in the background, made the search task more difficult. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: Accepted

Arctic soils store half of the global soil organic carbon (OC) pool and twice as much C as is currently present in the atmosphere. A considerable part of these carbon pools are stored in permafrost. Amplified climate warming in the Arctic will thaw permafrost and remobilize some of these substantial carbon stocks into the active carbon cycle, potentially causing positive feedback to global warming. Despite the global importance of this mechanism, our understanding of the fate of these thawing organic carbon (OC) pools is still poor, particularly regarding its degradation potential. This makes good estimates on greenhouse gas emissions versus coastal reburial impossible. This doctoral thesis aims to improve our understanding on the fate of high-latitude terrestrial OC during fluvial and coastal transport. In two study regions, the Bothnian Bay and the East Siberian Sea, we apply a wide range of bulk, molecular and isotopic geochemical analyses to reveal information on sources, age, degradation and transport routes. Our results show that both study regions receive and store large amounts of terrestrial OC, largely derived from peatlands (paper I, II and IV). This terrestrial matter undergoes extensive degradation in both the water column and surface sediments (paper I, III and IV). Surface sediments in the East Siberian Sea show a offshore-decreasing input of riverine OC and a considerable and constant input of OC from coastal erosion. The strong imprint of rapidly settling coastal OC far out on the shelf may be explained by a strong benthic boundary layer transport in combination with offshore ice-transport and selective preservation of erosion OC compared to riverine OC (paper IV). Molecular radiocarbon data allowed us to distinguish between two (sub-)Arctic soil OC pools that show a remarkably different susceptibility to degradation upon arrival in the coastal system; a young and easily degradable pool originating in surface peatlands, and an old and recalcitrant pool originating in deep mineral soils and coastal mineral Pleistocene deposits (paper III and IV). Our first estimates suggest that, in the Bothnian Bay coastal system, mineral soil OC is at least 20 times less susceptible to degradation than peatland OC (paper III). Hence, a considerable part of the thaw-released mineral OC pool may simply be relocated to coastal sediments instead of being emitted to the atmosphere. / At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Accepted. Paper 4: Manuscript.

In the scope of future population support, agricultural productivity, in particular in sub-Saharan Africa, has to increase drastically to meet the UN’s millennium development goals of eradicating extreme poverty and hunger by 2015. Water availability in the root-zone limits crop production in large parts of the developing world. As competition for fresh water increases, water of lower quality, for example saline or polluted water, is often used for irrigation. Low-cost drip systems are suitable for saline water irrigation because they effectuate a minimisation of salt accumulation, leaf burn and peaks in salt concentration. Nonetheless, all types of saline water irrigation contain the risk for causing soil salinisation. Thus, in order to achieve long-term sustainability of these systems, appropriate management strategies are needed. The choice of management practices may be influenced by local conditions such as climate, soil and irrigation water salinity. A litera-ture review showed that there is a potential for saline water irrigation in sub-Saharan Africa in water scarce areas. Low-cost drip irrigation with saline water (6 dS m-1) was successfully used to irrigate two consecutive crops of tomato in semi-arid South Africa. An integrated ecosystems model was developed to simulate long-term yield and salt accumulation in a drip-irrigated agricultural system for a range of salinities, climates and management techniques. Crop, salt and water balance data from two field experiments conducted in Israel and South Africa, respectively, were used to parameterise and test the model. Emphasis was placed on testing the usability of the model as a tool for evaluating the importance of certain plausible management options of low-cost, drip-irrigation systems. Therefore, particular focus was directed towards correctly describing soil salinity stress on plant growth and soil evaporation from a distributed (wetted and dry) surface. In addition, the model was developed to function for different climates without having to change any other parameters or variables except for the actual climatic data. Simulations were subsequently run over a 30-year period to study long-term yield and salt accumulation in the soil profile for two sites in South Africa, demonstrating the applicability of the model. Model simulations showed that high soil salinities reduced crop growth and thus increased both drainage and soil evaporation. Further, covering the soil with a plastic sheet led to a reduction of soil evaporation and a subsequent increase in both transpiration and drainage. Rainfall was crucial for the leaching of salts from the soil, and thus in regions with low levels of rainfall, a higher leaching fraction of supplied saline irrigation water has to compensate for the lack of rain. However, a high leaching fraction also causes large amounts of salt leaching, which could potentially pollute underlying groundwater and downstream ecosystems. This risk can be mitigated using mulching, which minimises non-productive water losses, thereby lowering irrigation water needs. The choice of irrigation water salinity, frequency of irrigation and soil coverage may differ between the farmer and the regional water manager due to different preferences. Furthermore, the study highlighted how environmental variables such as water use efficiency and radiation use efficiency can be used as indicators of system performance. Whereas the latter is first and foremost a general stress indicator, water use efficiency more precisely describes specific factors such as plant size, allocation patterns and evaporative demand, which will affect the exchange of carbon dioxide and water through the stomata. / QC 20101102

The oak district of Östergötland is one of the largest oak forests left in Europe and it harbours many threatened species dependent on old hollow trees. In this study, the saproxylic beetle Osmoderma eremita living in hollow oaks was used as a model species and parameterised for a metapopulation model (the incidence function model) at the level of individual trees. The aim was to set up a number of conservation management scenarios, where new oaks were added to increase the quality of the matrix and then simulate the resulting metapopulation occupancy, using three levels of dispersal. A real data set of hollow oaks was used as the base for modeling. Oaks were added to cells in a lattice covering the study landscape, where cell size, cell position and numbers of oaks per hectare were varied. The results show that a larger area of added oaks and a greater number of oaks per hectare will give a higher increase in total occupancy, no matter the dispersal, but the second smallest cell size used (3.4 km2 ) will give the highest response per effort for medium and high dispersal abilities, and smaller cells with greater number of oaks per area can be more effective. The spatial position of the increase in occupancy differs depending on dispersal ability of the focal species and should be considered in conservation management work. For unoccupied cells, the effort required to get the cell occupied will be smaller for cells having a greater number of oaks.

Global climate change has become an increasing source of concern due to the recent build-up of greenhouses gases in the atmosphere. The rocky intertidal zone, as the interface between land and sea, is particularly vulnerable to climate change. Many inhabitants of the intertidal zone are sessile and thus experience both terrestrial and aquatic lifestyles at low and high tides, respectively. When emersed at low tide, organisms experience a number of abiotic stresses including heat stress, desiccation stress, and low oxygen availability. Most intertidal organisms have evolved from marine animals and respire most efficiently in water. Barnacles are one such type of intertidal organism. At low tide barnacles face a tradeoff between access to oxygen and loss of water through evaporation. In this study, individuals of the species Balanus glandula, a common intertidal barnacle, were exposed to temperatures of 16°C, 24°C, 30°C, and 35°C for four hours in simulated low tide to determine when aerial respiration occurred. Oxygen levels were measured over the four hours of the exposure and oxygen consumption rates were calculated. Oxygen consumption occurred at all temperatures studied, but the rates at different temperatures were not significantly different from each other. The results showed that barnacles can conduct aerial respiration over the entire course of the low tide exposure despite the risk of desiccation. This indicates that ATP demand remains substantial throughout the low tide and that resorting to anaerobic respiration is not sufficient to meet metabolic needs during low tide exposure.

Most urban areas of developing countries were hitherto experiencing unprecedented growth in their population, the phenomenon commonly referred to as urbanization, which in this study can be said to be the proportion of urban population relative to the total population of a region. This phenomenon has opportunities vis-à-vis challenges, whose impact on natural resources in general and water resources in particular, cannot be over- emphasized. It is within the context of these urban challenges that this study attempts to look into and possibly assess the situation in the urban and peri- urban areas of Kumasi Metropolitan Area (KMA) in Ghana, whose urbanization processes is prejudiced by this study to be increasing rapidly. The study specifically attempted to assess thechanges in the urbanization patterns and the possible future urbanization trend of the area within a specific time frame. The study also attempts to look at the causes of this urbanization, and its impact on water resources in the Area, both qualitatively and quantitatively, envisaged to be the results of socio-economic activities taking place in the Area. Finally, the study attempts to look into the measures put in place to curb these challenges. Amid paucity of data, however, the study reveals that the most single contributor of urbanization processes in the area has been migration from the countryside, and in particular from the northern part of the country. The study also reveals the fact that even though the general quality standard of some water resources is better, the largely uncontrolled socio-economic activities, coupled with the deplorable sanitary conditions in the KMA, has potential to degrade the water resources in the KMA. In addition, the study reveals that little attention is given, in terms of policy formulation to curb this urbanization processes and to protect water resources in the area.

An understanding of the impacts on freshwater systems from water management and development practices and the recognition that freshwater ecosystems are dependent on various aspects of the natural hydrological variability has given rise to a relatively new field of science commonly referred to as environmental flows. The assessment and application of environmental flows has advanced considerably in the last ten years. To coincide with the emergence and expansion of the environmental flows concept around the world, this survey study was undertaken aiming to identify people’s perceptions and interpretations of the environmental flows concept and its role in water management. It also aims to add to existing knowledge of the extent to which the concept is being applied, how it is being translated into policy and practice and the major challenges and opportunities that exist for continued understanding and implementation. The survey was distributed to a range of people representing different water-related sectors and regions around the world. A total of 272 responses representing 64 countries in the six major regions of the world was received. The responses were compiled and analysis of aspects of the respondents backgrounds as well as the questions were conducted using the computer statistical program SPSS. Representation of specific groups, particularly water user groups, and specific regions in the survey however was low, demonstrating possible limitations of the survey distribution method as well as the lack of concept awareness and application in many parts of the world. The ways in which people define and interpret the concept varied widely. The degree to which the concept was applied shows the growing recognition around the world of the need to consider the environmental water requirements when making decisions on water allocations. Despite the growing recognition many areas do not yet apply the concept. The survey allowed the opportunity for respondents to highlight what they perceived asthe major obstacles and difficulties for the concept within their respective areas. Lack of understanding among stakeholders of the socio-economic costs and benefits associated with concept implementation and a lack of political will were the two most common obstacles for the continued adoption and application of environmental flows around the world. Overall, the survey delivered promising signs for the continued evolution of environmental flows within water management. There was widespread opinion that the concept of environmental flows was an essential element in the efforts to achieve sustainable management of water resources.

Invasive species are an increasingly severe conservation problem that can dramatically alter native plant communities. Although ecologists have proposed many mechanisms for the dominance of invasive species, superior competitive ability is one of the longest standing hypotheses. In winter annual plant communities, germination timing affects competition among plants. I hypothesized that grass invasion has changed the costs and benefits of early and late germination, and that species with flexible germination timing would compete better with invasives. Experiments at the Bernard Field Station in Claremont, CA and germinator trials in a controlled environment were used to examine the survivorship and germination rate of three native forbs in the presence or absence of invasive grass competition. Germinator trials revealed that most Clarkia purpurea seeds germinated in fall conditions, though newer seeds had higher proportions germinate under winter conditions. Older seeds had a lower germination success, indicating a potential decrease in seed viability. In the field experiment, November germinants had higher survival rates than October germinants for Amsinckia menziesii and Phacelia distans, and both species had similar numbers of new germinants at each census. Removal of invasive grasses did not significantly affect the survival of either species, though a trend towards increased survivorship was observed in removal plots of November germinants. Taken together, these results show evidence for variation in germination timing and responses to environmental cues among native annual seeds, and also support the idea that germination timing has important consequences for survivorship, and potentially competitive interactions, with invasive grasses.

I studied water bird use of two lakes in the Claremont-Upland area to determine what physical, chemical, and biological aspects of these lakes provide suitable water bird habitat and food resources. I censused the Bernard Field Station Lake in Claremont and a gravel pit freshwater area in Upland from 10/85 to 3/86 for water bird use. I also mapped these sites, noted their water surface area and water depth changes, monitored their water chemistry, and censused their vegetation. The results of this work showed more total water birds per hour of observation time, and more birds per hour of observation time of each food preference type, at the Upland Lakes than at the BFS Lake, except for diving ducks, which I found at both sites in similar abundance, and coots, which I found at the BFS Lake in greater abundance than at the Upland Lakes. The Shannon-Weiner Index of Diversity, H', used to determine bird species diversity, was higher for most individual census dates and on average, at the Upland Lakes than at the BFS Lake. The Upland Lakes had fewer species and less abundance of true aquatic plants than the BFS Lake; however, the BFS Lake had fewer different types of habitat (i.e. open shoreline, thick emergent shoreline vegetation, mudflats, grassy areas, etc .) than did the Upland Lakes. The Upland Lakes, although originally very similar to the BFS Lake in total water surface area, came to have four times the water surface area of the BFS Lake as time progressed, due to winter rainfall and runoff. The results of bird censuses also showed many more migrant than resident birds using the Upland Lakes area, while few migrant birds used the BFS Lake. Water bird use differences between these sites are the resuIt of the interaction of the unique ecological factors of each site. The Upland Lakes provide more diverse habitats, greater water surface area, a more accessible, open, isolated location for stopovers for migratory birds than the BFS Lake provides. The BFS Lake provides only two major habitat types for water bird use: thick shoreline emergent vegetation (mostly cattails), and open water. Diving ducks and coots utilize these habitats well and thus, with the exception of migratory flocks of diving ducks, used the BFS Lake as frequently, or more frequently than they used the Upland Lakes. Other birds that forage in muddy, open shore or grassy, open shore areas preferred the Upland Lakes area (dabbling ducks and shorebirds). Additional observation of similar water area in Claremont, Upland, and Montclair, California could produce a larger data base to demonstrate conclusively such tentative findings of this study as size of water surface area being directly proportional to amount of migratory bird use.

Studies have shown that air pollution, as well as bark fissure depth and sun exposure of a tree can have an effect on lichen growth as well as abundance of lichen species. The aim of this study was to find out the relative importance of these factors. 211 oaks in south eastern Sweden were surveyed for presence of 17 lichen species, as well as the total number of lichen species. Half of the trees were situated in urban areas and half in the countryside. For each tree the bark fissure depth was measured and the sun exposure of the trunk was estimated. The results showed a significant negative effect on a majority of lichens growing in an urban environment and a significant positive effect on a majority of lichens growing on trees with deep bark fissures. The sun exposure was a less important factor but could not be excluded as a factor affecting lichen occurrence. These results show the negative effect urbanization can have on rare lichen species, as well as be used in the development and maintenance for the nature reserves containing them