Landscape fragmentation can be defined as the breaking up of a habitat, ecosystem or land-use type into smaller parcels (Forman, 1995). It is the disintegration of existing geographical patterns by the introduction of new elements or structures in such a way that the existing or desired functions are impaired (Gunlinck and Wagendorp, 2002). Ecosysem fragmentation can be described by three main effects: increase in isolation of the ecosystem patches, decrease in their size, and increase in their exposure to external disturbances, which in turn may lead to a decline in the ecosystem biodiversity as well as in its stability and ability to recover from disturbances (Geneletti, 2002; Baskent, 1999; Saunders et al., 1991). Recently, much of the literature on this topic has attempted to quantify the degree of landscape fragmentation through the use of landscape metrics and indicators. There has been a considerable effort in this field in the last two decades, enables by the rapid development of remote sensing and geographic information systems (GIS) (Herzog, 2002).

The North Yukon Planning commission released a land use scenarios report in 2009 in an effort to facilitate informed discussions about key land use issues and practices, levels of landscape change, and potential land use impacts. The project had three major objectives: 1) explore potential outcomes of plausible future land use scenarios in the North Yukon Planning Region, 2) identify and explore natural factors and human land uses and land use practices that act as key drivers of landscape change, and 3) compare the potential outcomes of different future land use scenarios against a set of socio-economic, land use and ecological indicators (NYPC, 2009). The report used two indicators, linear density and surface disturbance, to assess the levels of landscape disturbance. The former is defined as the total length of all linear features (roads, trails, pipelines, seismic lines, etc.) within a given area; it is expressed as km of linear features per km² of study area (km/km²). The latter is defined as the visible “footprint” of human land use; it is the amount of area physically disturbed by human activities. The total amount of surface disturbance is measured either in hectares (ha) or the proportion of the study area affected (%) (NYPC, 2009).

The purpose of our study is to determine if linear density and surface disturbance are the best indicators for assessing ecological integrity, more specifically landscape fragmentation, for the North Yukon Land Use Scenarios Report. This study will explore other projects that have used these indicators and will assess whether or not they were the most suitable in this particular context. Cultural interpretation and the historic dimension of the landscape are important factors in the definition of adequate references in fragmentation studies (Gunlinck and Wagendorp, 2002). Given the wide range of indicators available, the study will look at the advantages and drawbacks of linear density and surface disturbance and why they were chosen as indicators for the North Yukon Land Use Scenarios Report. In addition, this paper will introduce a third indicator, the effective mesh size (m_eff), in an effort to further analyse the degree of landscape fragmentation in the North Yukon Region. Effective mesh size is an expression of the probability that any two locations in the landscape are connected and therefore not separated by barriers such as roads (Jaeger, 2000). It can also be interpreted as the average size of the area that an animal placed randomly in the landscape will be able to access without crossing barriers (Girvetz et al., 2008).

· Discuss fragmentation geometries (FG) and differences in CUT and CBC measures

· Discuss how this may tie into existing and future scenarios reports