Mining in Northern British Columbia

The history of the settlement of the province is tied to patterns of exploration and min development. In Northern British Columbia the Cariboo goldfields provided the impetus for settlement of the region and the beginning for mining to extend into the watern and northern regions in a series of minor gold rushes. The northern half of the province has a geological diverse mineral base that supports a wide variety of mining, and a gradual improvement of exploration and mining methods due to scientific knowledge and technology provided opportunities for lode gold and base metal mines to be developed. The success of mining is based on world ore prices and competitive markets that impact the economic viability of developing a mine. Mining faces increasing pressures in the northern half of the province due to other resource values, such as tourism or protected areas, that claim and compete for a similar land base.

Integrated Bayesian network frameworks for modelling complex ecological issues

Ecological problems are typically multi faceted and need to be addressed from a scientific and a management perspective. There is a wealth of modelling and simulation software available, each designed to address a particular aspect of the issue of concern. Choosing the appropriate tool, making sense of the disparate outputs, and taking decisions when little or no empirical data is available, are everyday challenges facing the ecologist and environmental manager. Bayesian Networks provide a statistical modelling framework that enables analysis and integration of information in its own right as well as integration of a variety of models addressing different aspects of a common overall problem. There has been increased interest in the use of BNs to model environmental systems and issues of concern. However, the development of more sophisticated BNs, utilising dynamic and object oriented (OO) features, is still at the frontier of ecological research. Such features are particularly appealing in an ecological context, since the underlying facts are often spatial and temporal in nature. This thesis focuses on an integrated BN approach which facilitates OO modelling. Our research devises a new heuristic method, the Iterative Bayesian Network Development Cycle (IBNDC), for the development of BN models within a multi-field and multi-expert context. Expert elicitation is a popular method used to quantify BNs when data is sparse, but expert knowledge is abundant. The resulting BNs need to be substantiated and validated taking this uncertainty into account. Our research demonstrates the application of the IBNDC approach to support these aspects of BN modelling. The complex nature of environmental issues makes them ideal case studies for the proposed integrated approach to modelling. Moreover, they lend themselves to a series of integrated sub-networks describing different scientific components, combining scientific and management perspectives, or pooling similar contributions developed in different locations by different research groups. In southern Africa the two largest free-ranging cheetah (Acinonyx jubatus) populations are in Namibia and Botswana, where the majority of cheetahs are located outside protected areas. Consequently, cheetah conservation in these two countries is focussed primarily on the free-ranging populations as well as the mitigation of conflict between humans and cheetahs. In contrast, in neighbouring South Africa, the majority of cheetahs are found in fenced reserves. Nonetheless, conflict between humans and cheetahs remains an issue here. Conservation effort in South Africa is also focussed on managing the geographically isolated cheetah populations as one large meta-population. Relocation is one option among a suite of tools used to resolve human-cheetah conflict in southern Africa. Successfully relocating captured problem cheetahs, and maintaining a viable free-ranging cheetah population, are two environmental issues in cheetah conservation forming the first case study in this thesis. The second case study involves the initiation of blooms of Lyngbya majuscula, a blue-green algae, in Deception Bay, Australia. L. majuscula is a toxic algal bloom which has severe health, ecological and economic impacts on the community located in the vicinity of this algal bloom. Deception Bay is an important tourist destination with its proximity to Brisbane, Australia’s third largest city. Lyngbya is one of several algae considered to be a Harmful Algal Bloom (HAB). This group of algae includes other widespread blooms such as red tides. The occurrence of Lyngbya blooms is not a local phenomenon, but blooms of this toxic weed occur in coastal waters worldwide. With the increase in frequency and extent of these HAB blooms, it is important to gain a better understanding of the underlying factors contributing to the initiation and sustenance of these blooms. This knowledge will contribute to better management practices and the identification of those management actions which could prevent or diminish the severity of these blooms.

A GIS framework for streamlining the Nature Refuge Gazettal process

Nature Refuges encompass the second largest extent of protected area estate in Queensland. Major problems exist in the data capture, map presentation, data quality and integrity of these boundaries. The spatial accuracies/inaccuracies of the Nature Refuge administrative boundaries directly influence the ability to preserve valuable ecosystems by challenging negative environmental impacts on these properties. This research work is about supporting the Nature Refuge Programs efforts to secure Queensland’s natural and cultural values on private land by utilising GIS and its advanced functionalities. The research design organizes and enters Queensland’s Nature Refuge boundaries into a spatial environment. Survey quality data collection techniques such as the Global Positioning Systems (GPS) are investigated to capture Nature Refuge boundary information. Using the concepts of map communication GIS Cartography is utilised for the protected area plan design. New spatial datasets are generated facilitating the effectiveness of investigative data analysis. The geodatabase model developed by this study adds rich GIS behaviour providing the capability to store, query, and manipulate geographic information. It provides the ability to leverage data relationships and enforces topological integrity creating savings in customization and productivity. The final phase of the research design incorporates the advanced functions of ArcGIS. These functions facilitate building spatial system models. The geodatabase and process models developed by this research can be easily modified and the data relating to mining can be replaced by other negative environmental impacts affecting the Nature Refuges. Results of the research are presented as graphs and maps providing visual evidence supporting the usefulness of GIS as means for capturing, visualising and enhancing spatial quality and integrity of Nature Refuge boundaries.

The Catlin Seaview Survey – kilometre-scale seascape assessment, and monitoring of coral reef ecosystems

1.Marine ecosystems provide critically important goods and services to society, and hence their accelerated degradation underpins an urgent need to take rapid, ambitious and informed decisions regarding their conservation and management. 2.The capacity, however, to generate the detailed field data required to inform conservation planning at appropriate scales is limited by time and resource consuming methods for collecting and analysing field data at the large scales required. 3.The ‘Catlin Seaview Survey’, described here, introduces a novel framework for large-scale monitoring of coral reefs using high-definition underwater imagery collected using customized underwater vehicles in combination with computer vision and machine learning. This enables quantitative and geo-referenced outputs of coral reef features such as habitat types, benthic composition, and structural complexity (rugosity) to be generated across multiple kilometre-scale transects with a spatial resolution ranging from 2 to 6 m2. 4.The novel application of technology described here has enormous potential to contribute to our understanding of coral reefs and associated impacts by underpinning management decisions with kilometre-scale measurements of reef health. 5.Imagery datasets from an initial survey of 500 km of seascape are freely available through an online tool called the Catlin Global Reef Record. Outputs from the image analysis using the technologies described here will be updated on the online repository as work progresses on each dataset. 6.Case studies illustrate the utility of outputs as well as their potential to link to information from remote sensing. The potential implications of the innovative technologies on marine resource management and conservation are also discussed, along with the accuracy and efficiency of the methodologies deployed.

Extinction risk in cloud forest fragments under climate change and habitat loss

Aim: To quantify the consequences of major threats to biodiversity, such as climate and land-use change, it is important to use explicit measures of species persistence, such as extinction risk. The extinction risk of metapopulations can be approximated through simple models, providing a regional snapshot of the extinction probability of a species. We evaluated the extinction risk of three species under different climate change scenarios in three different regions of the Mexican cloud forest, a highly fragmented habitat that is particularly vulnerable to climate change. Location: Cloud forests in Mexico. Methods: Using Maxent, we estimated the potential distribution of cloud forest for three different time horizons (2030, 2050 and 2080) and their overlap with protected areas. Then, we calculated the extinction risk of three contrasting vertebrate species for two scenarios: (1) climate change only (all suitable areas of cloud forest through time) and (2) climate and land-use change (only suitable areas within a currently protected area), using an explicit patch-occupancy approximation model and calculating the joint probability of all populations becoming extinct when the number of remaining patches was less than five. Results: Our results show that the extent of environmentally suitable areas for cloud forest in Mexico will sharply decline in the next 70 years. We discovered that if all habitat outside protected areas is transformed, then only species with small area requirements are likely to persist. With habitat loss through climate change only, high dispersal rates are sufficient for persistence, but this requires protection of all remaining cloud forest areas. Main conclusions: Even if high dispersal rates mitigate the extinction risk of species due to climate change, the synergistic impacts of changing climate and land use further threaten the persistence of species with higher area requirements. Our approach for assessing the impacts of threats on biodiversity is particularly useful when there is little time or data for detailed population viability analyses. © 2013 John Wiley & Sons Ltd.

The Why, What, and How of Global Biodiversity Indicators Beyond the 2010 Target

The 2010 biodiversity target agreed by signatories to the Convention on Biological Diversity directed the attention of conservation professionals toward the development of indicators with which to measure changes in biological diversity at the global scale. We considered why global biodiversity indicators are needed, what characteristics successful global indicators have, and how existing indicators perform. Because monitoring could absorb a large proportion of funds available for conservation, we believe indicators should be linked explicitly to monitoring objectives and decisions about which monitoring schemes deserve funding should be informed by predictions of the value of such schemes to decision making. We suggest that raising awareness among the public and policy makers, auditing management actions, and informing policy choices are the most important global monitoring objectives. Using four well-developed indicators of biological diversity (extent of forests, coverage of protected areas, Living Planet Index, Red List Index) as examples, we analyzed the characteristics needed for indicators to meet these objectives. We recommend that conservation professionals improve on existing indicators by eliminating spatial biases in data availability, fill gaps in information about ecosystems other than forests, and improve understanding of the way indicators respond to policy changes. Monitoring is not an end in itself, and we believe it is vital that the ultimate objectives of global monitoring of biological diversity inform development of new indicators. ©2010 Society for Conservation Biology.

Mitigating undesirable impacts in the marine environment: A review of market-based management measures

Internationally, marine biodiversity conservation objectives are having an increasing influence on the management of commercial fisheries. While this is largely being implemented through Marine Protected Areas (MPAs) other management measures, such as market based instruments (MBIs), have proved to be effective at managing target species catch in fisheries and reducing environmental impacts in industries such as mining and tourism. Market-based management measures aim to mitigate the impacts of activities by better aligning the incentives their participants face with the objectives of management, changing their behavior as a consequence. In this paper, we review the potential of MBIs as management tools to mitigate undesirable environmental impacts associated with commercial fishing. Where they exist, examples of previous applications are described and the factors that influence their applicability and effectiveness are discussed. Several fishing methods and impacts are considered and suggest that whilst no single approach is most appropriate in all circumstances either replacing or complementing existing management arrangements with MBIs has the potential to improve environmental performance. This has a number of implications. From the environmental perspective they should enable levels of undesirable impacts such as damage to sensitive habitat or the bycatch of protected species of turtles, marine mammals, and seabirds to be reduced. The increased flexibility MBIs allow industry when developing solutions also has the potential to reduce costs to both the industry and managers, improving the cost-effectiveness of regulation as a result. Further, in the increasingly relevant case of MPAs the need for publicly funded compensation, often paid to industry when vessels are excluded from grounds, may also be significantly reduced if improved environmental performance makes it possible for some industry members to continue operating.

A review of current knowledge of the weedy species Themeda quadrivalvis (grader grass)

This review of grader grass (Themeda quadrivalvis) attempts to collate current knowledge and identify knowledge gaps that may require further research. Grader grass is a tropical annual grass native to India that is now spread throughout many of the tropical regions of the world. In Australia, it has spread rapidly since its introduction in the 1930s and is now naturalised in the tropical areas of Queensland, the Northern Territory and Western Australia and extends south along the east coast to northern New South Wales. It is a vigorous grass with limited palatability, that is capable of invading native and improved pastures, cropping land and protected areas such as state and national parks. Grader grass can form dense monocultures that reduce biodiversity, decrease animal productivity and increase the fire hazard in the seasonally dry tropics. Control options are based on herbicides, grazing management and slashing, while overgrazing appears to favour grader grass. The effect of fire on grader grass is inconclusive and needs to be defined. Little is known about the biology and impacts of grader grass in agricultural and protected ecosystems in Australia. In particular, information is needed on soil seed bank longevity, seed production, germination and growth, which would allow the development of management strategies to control this weedy grass.

Queensland Coastal Wetland Resources: Cape Tribulation to Bowling Green Bay

This report provides key resource data for the ongoing assessment of the requirement for additional Marine Protected Areas (e.g. FHAs under the Queensland Fisheries Act 1994) in regions of high fish habitat value in northern Queensland from Cape Tribulation to Bowling Green Bay (hereafter referred to as the Study Area). The study also provides baseline information on the coastal wetlands within this Study Area for consideration in the Ramsar site nomination process. The Study Area extends from Cape Tribulation (16o 6’S, 145o 24’E) to Bowling Green Bay (19o 30’S, 147o 24’E) in tropical north Queensland. The project aimed to: 1. document and map the coastal wetland communities of the Study Area; 2. document levels of existing disturbance to and protection of the wetlands; 3. examine existing recreational, indigenous and commercial fisheries resources in the region; 4. evaluate the conservation values of the areas investigated from the viewpoint of fisheries productivity and as habitat for important and/or threatened species for future FHA/MPA declaration. Dataset URL Link: Queensland Coastal Wetlands Resources Mapping data. [Dataset]

Community forestry and environmental literacy in northern Thailand : Towards collaborative natural resource management and conservation

Conservation and sustainable management of tropical forests needs a holistic approach: in addition to ecological concerns, socio-economic issues including cultural aspects must be taken into consideration. An ability to adapt practices is a key to successful collaborative natural resource management. Achieving this requires local participation and understanding of local conceptions of the environment. This study examined these issues in the context of northern Thailand. Northern uplands are the home of much of the remaining natural forest in Thailand and several ethnic minority groups commonly referred to as hill tribes. The overall purpose of this study was to grasp a regional view of an ethnically diverse forested area and to elicit prospects to develop community forestry for conservation purposes and for securing people s livelihood. Conservation was a central goal of management as the forests in the area were largely designated as protected. The aim was to study local perceptions, objectives, values and practices of forest management, under the umbrella of the concept environmental literacy, as well as the effects of forest policy on community management goals and activities. Environmental literacy refers to holistic understanding of the environment. It was used as a tool to examine people s views, interests, knowledge and motivation associated to forests. The material for this study was gathered in six villages in Chiang Mai Province. Three minority groups were included in the study, the Karen, Hmong and Lawa, and also the Thai. Household and focus group interviews were conducted in the villages. In addition, officials at district, regional and national levels, workers of non-governmental organisations, and academics were interviewed, and some data were gathered from the students of a local school. The results showed that motivation for protecting the forests existed among each ethnic group studied. This was a result of culture and traditions evolved in the forest environment but also of a need to adapt to a changed situation and environment and to outside pressures. The consequences of deforestation were widely agreed on in the villages, and the impact of socio-economic changes on the forests and livelihood was also recognised. The forest was regarded as a source of livelihood providing land, products and services essential to the people inhabiting rural uplands. Traditions, fire control, cooperation, reforestation, separation of protected and utilisable areas, and rules were viewed as central for conservation. For the villagers, however, conservation meant sustainable use, whereas the government has tended to prefer strict restrictions on forest resource use. Thus, conflicts had arisen. Between communities, cooperation was more dominant than conflict. The results indicated that the heterogeneity of forest dwellers, although it has to be recognised, should not be overemphasised: ethnic diversity can be considered as no major obstacle for successful community forestry. Collaborative management is particularly important in protected areas in order to meet the conservation goals while providing opportunities for livelihood. Forest management needs more positive incentives and increased dialogue.

Queensland Coastal Wetland Resources: The Whitsunday Region

This report provides key resource data for the ongoing assessment of the requirement for additional Marine Protected Areas (e.g. FHAs under the Queensland Fisheries Act 1994) in regions of high fish habitat value in the Whitsunday Region from Gloucester Island to Cape Hillsborough (hereafter referred to as the Study Area). The study also provides baseline information on the coastal wetlands within this Study Area for consideration in the Ramsar site nomination process. The project aimed to: 1. document and map the coastal wetland communities of the Study Area; 2. document levels of existing disturbance to and protection of the wetlands; 3. examine existing recreational, indigenous and commercial fisheries resources in the region; 4. evaluate the conservation values of the areas investigated from the viewpoint of fisheries productivity and as habitat for important and/or threatened species for future FHA/MPA declaration.

Fencing artificial waterpoints failed to influence density and distribution of red kangaroos (Macropus rufus)

Provision of artificial waterpoints in Australian rangelands has resulted in an increase in the range and density of kangaroos. At high densities, kangaroos can inhibit vegetation regeneration, particularly in some protected areas where harvesting is prohibited. Fencing off waterpoints has been proposed to limit these impacts. Our aim was to determine whether fencing off waterpoints during a drought (when kangaroos would be especially water-limited) would influence the density and distribution of red kangaroos (Macropus rufus). Two waterpoints were fenced within the first 6 months of the 27-month study and a further two waterpoints were kept unfenced as controls in Idalia National Park, western Queensland. We estimated kangaroo densities around waterpoints from walked line-transect counts, and their grazing distribution from dung-pellet counts. Fencing off waterpoints failed to influence either the density or distribution up to 4 km from the waterpoints. Our results indicate that food availability, rather than the location of waterpoints, determines kangaroo distribution. Few areas in the rangelands are beyond kangaroos' convenient reach from permanent waterpoints. Therefore, fencing off waterpoints without explicitly considering the spatial context in relation to other available water sources will fail to achieve vegetation regeneration.

Participation or further exclusion? : Contestations over forest conservation and control in the East Usambara Mountains, Tanzania

This Ph.D. thesis Participation or Further Exclusion? Contestations over Forest Conservation and Control in the East Usambara Mountains, Tanzania describes and analyses the shift in the prevailing discourse of forest and biodiversity conservation policies and strategies towards more participatory approaches in Tanzania, and the changes in the practises of resource control. I explore the scope for and limits to the different actors and groups who are considered to form the community, to participate in resource control, in a specific historical and socio-economic context. I analyse whether, how and to which extent the targets of such participatory conservation interventions have been able to affect the formal rules and practices of resource control, and explore their different responses and discursive and other strategies in relation to conservation efforts. I approach the problematic through exploring certain participatory conservation interventions and related negotiations between the local farmers, government officials and the external actors in the case of two protected forest reserves in the southern part of the East Usambaras, Tanzania. The study area belongs to the Eastern Arc Mountains that are valued globally and nationally for their high level of biodiversity and number of endemic and near endemic species. The theoretical approach draws from theorising on power, participation and conservation in anthropology of development and post-structuralist political ecology. The material was collected in three stages between 2003 and 2008 by using an ethnographic approach. I interviewed and observed the actors and their resource use and control practices at the local level, including the representatives of the villagers living close to the protected forests and the conservation agency, but also followed the selected processes and engaged with the non-local agencies involved in the conservation efforts in the East Usambaras. In addition, the more recent processes of change and the actors strategies in resource control were contextualised against the social and environmental history of the study area and the evolvement of institutions of natural resource control. My findings indicate that the discourse of participation that has emerged in global conservation policy debate within the past three decades, and is being institutionalised in the national policies in many countries, including Tanzania, has shaped the practices of forest conservation in the East Usambaras, although in a fragmented and uneven way. Instrumental interpretation of participation, in which it is to serve the goals of improving the control of the forest and making it more acceptable and efficient, has prevailed among the governmental actors and conservation organisations. Yet, there is variation between the different projects and actors promoting participatory conservation regarding the goals and means of participation, e.g. to which extent the local people are to be involved in decision-making. The actors representing communities also have their diverse agendas, understandings and experiences regarding the rationality, outcomes and benefits of being involved in forest control, making the practices of control fluid. The elements of the exclusive conservation thinking and practices co-exist with the more recent participatory processes, and continue to shape the understandings and strategies of the actors involved in resource control. The ideas and narratives of the different discourses are reproduced and selectively used by the parties involved. The idea of forest conservation is not resisted as such by most of the actors at local level, quite the opposite. However, the strict regulations and rules governing access to resources, such as valuable timber species, continue to be disputed by many. Furthermore, the history of control, such as past injustices related to conservation and unfulfilled promises, undermines the participation of certain social groups in resource control and benefit sharing. This also creates controversies in the practices of conservation, and fuels conflicts regarding the establishment of new protected areas. In spite of this, the fact that the representatives of the communities have been invited to the arenas where information is shared, and principles and conditions of forest control and benefit sharing are discussed and partly decided upon, has created expectations among the participants, and opened up opportunities for some of the local actors to enhance their own, and sometimes wider interests in relation to resource control and the related benefits. The local actors experiences of the previous government and other interventions strongly affect how they position themselves in relation to conservation interventions, and their responses and strategies. However, my findings also suggest, in a similar way to research conducted in some other protected areas, that the benefits of participation in conservation and resource control tend to accrue unevenly between different groups of local people, e.g. due to unequal access to information and differences in their initial resources and social position.

Where and how to conserve: Extending the scope of spatial reserve network design

Ongoing habitat loss and fragmentation threaten much of the biodiversity that we know today. As such, conservation efforts are required if we want to protect biodiversity. Conservation budgets are typically tight, making the cost-effective selection of protected areas difficult. Therefore, reserve design methods have been developed to identify sets of sites, that together represent the species of conservation interest in a cost-effective manner. To be able to select reserve networks, data on species distributions is needed. Such data is often incomplete, but species habitat distribution models (SHDMs) can be used to link the occurrence of the species at the surveyed sites to the environmental conditions at these locations (e.g. climatic, vegetation and soil conditions). The probability of the species occurring at unvisited location is next predicted by the model, based on the environmental conditions of those sites. The spatial configuration of reserve networks is important, because habitat loss around reserves can influence the persistence of species inside the network. Since species differ in their requirements for network configuration, the spatial cohesion of networks needs to be species-specific. A way to account for species-specific requirements is to use spatial variables in SHDMs. Spatial SHDMs allow the evaluation of the effect of reserve network configuration on the probability of occurrence of the species inside the network. Even though reserves are important for conservation, they are not the only option available to conservation planners. To enhance or maintain habitat quality, restoration or maintenance measures are sometimes required. As a result, the number of conservation options per site increases. Currently available reserve selection tools do however not offer the ability to handle multiple, alternative options per site. This thesis extends the existing methodology for reserve design, by offering methods to identify cost-effective conservation planning solutions when multiple, alternative conservation options are available per site. Although restoration and maintenance measures are beneficial to certain species, they can be harmful to other species with different requirements. This introduces trade-offs between species when identifying which conservation action is best applied to which site. The thesis describes how the strength of such trade-offs can be identified, which is useful for assessing consequences of conservation decisions regarding species priorities and budget. Furthermore, the results of the thesis indicate that spatial SHDMs can be successfully used to account for species-specific requirements for spatial cohesion - in the reserve selection (single-option) context as well as in the multi-option context. Accounting for the spatial requirements of multiple species and allowing for several conservation options is however complicated, due to trade-offs in species requirements. It is also shown that spatial SHDMs can be successfully used for gaining information on factors that drive a species spatial distribution. Such information is valuable to conservation planning, as better knowledge on species requirements facilitates the design of networks for species persistence. This methods and results described in this thesis aim to improve species probabilities of persistence, by taking better account of species habitat and spatial requirements. Many real-world conservation planning problems are characterised by a variety of conservation options related to protection, restoration and maintenance of habitat. Planning tools therefore need to be able to incorporate multiple conservation options per site, in order to continue the search for cost-effective conservation planning solutions. Simultaneously, the spatial requirements of species need to be considered. The methods described in this thesis offer a starting point for combining these two relevant aspects of conservation planning.

Reproduction and population structure in European aspen

The European aspen (Populus tremula) is a keystone species for biodiversity in boreal forests. However, the future of aspen may be threatened, because large aspens have mostly been removed from managed forests, whereas regeneration and the long-term persistence of mature trees are subjects of concern in protected areas. Aspen is a pioneer tree, and it can reproduce both sexually by seed and asexually by root suckers. Through asexual reproduction aspen forms clones, groups of genetically identical trees (ramets). In my thesis, I have studied the structure of aspen populations in terms of number, size, clonal and demographic properties. Additionally, I have investigated the emergence and survival of seedlings as well as the seed quantity and quality in crosses between the European and hybrid aspen. To study the regeneration and population structure, mature aspens were recorded in old-growth and managed forests in eastern Finland based on a large-scale inventory (11 400 ha). In addition, small aspen trees were surveyed on sample plots. Clonal structure was investigated both by morphological characters and by DNA-based markers (microsatellites). Seedling emergence and survival was studied with two sowing experiments. With crosses between European and hybrid aspens we wanted to study whether elevated temperatures due to climate change would benefit the different crosses of European and hybrid aspen unequally and thus affect the gene flow between the two species. The average volumes of mature aspen were 5.3 m3/ha in continuous old-growth, and 0.8 m3/ha in managed forests. Results indicate also that large aspen trees in managed forests are a legacy of the past less intensively managed forest landscapes. Long-term persistence of aspen in protected areas can only be secured by restoration measures creating sufficiently large gaps for regeneration. More emphasis should be given to sparing aspens in thinnings and to retaining of mature aspens in regeneration cutting in managed forests. Aspen was found to be spatially aggregated in the landscape. This could be explained by site type, disturbance history and / or limitations in seed dispersal. Clonal structure does not explain the spatial aggregation, since average size of the clones was only 2.3 ramets, and most clones (70 %) consisted of just one ramet. The small size of the clones suggests that most of them are relatively young. Therefore, sexual reproduction may be more common than has previously been thought. Seedling emergence was most successful in mineral soil especially, when the site had been burned. Only few seedlings occurred on humus. Survival of the seedlings was low, and strongly dependent on moisture, but also on seedbed conditions. The seeds were found to maintain their germinability longer than has earlier been thought to be possible. Interspecific crosses produced more seeds with higher quality than intraspecific crosses. When temperature was elevated, germination of hybrid aspen seeds increased more than seeds from P. tremula x P. tremula crosses. These results suggest that hybrid aspen may have a significant genetic impact on the European aspen, and this effect may become strengthened by climate warming.