Integrating trees outside forests into national forest inventories

Sammanfattning: Trees Outside Forests (TOF) offer a wide range of ecological, economic, and social services. For example, they sequester carbon, provide wood for fuel and construction, protect soils from erosion, and contribute to the conservation of biological diversity. In particular in regions with low forest cover, TOF often have a substantial role in meeting society’s demands for resources such as wood and fodder. Information about trees is required for many purposes and at many geographical scales, and it has been recognised that substantial tree resources are overseen when focussing on forests alone. At the global scale, reporting obligations linked to agreements such as the Kyoto protocol are important. However, information is also needed for policy making at national scale and for integrated management by rural and urban planners. The focus of this thesis is the provision of national level information about TOF resources. From a literature review it was concluded that many national forest inventories have widened the scope of their inventories through including TOF. However, in general there is a shortage of information about TOF resources on a global scale. Further, very few methodological studies exist on how TOF could be integrated into national forest inventories. A central question of this thesis thus is how an integrative monitoring approach such as a national tree inventory would look like. Existing data from country-level TOF inventories across three continents were re-analysed. It was found that TOF contribute substantially to national tree biomass and carbon stocks. A method for simulating the spatial distribution of TOF elements at the landscape scale was investigated at selected study sites in Skåne, in the south of Sweden. The aim was to reconstruct existing patterns by methods from material sciences that might be used for modelling TOF patterns. Finally, a sampling simulation study was conducted to assess the potential of different inventory strategies to form the basis for national tree inventories. It was found that the combination of data from field sample plots and airborne laser scanning offers great potential in connection with model-assisted estimation. The results of this thesis may serve as a starting point for moving from a forest-centred view on tree monitoring towards integrative monitoring approaches that consider all trees that grow in a study region as valuable.