Principle - Ecological

Criterion- Landscape patterns support native populations

Indicator – Corridors of unlogged forests are retained.

Box B: Definition:

On of the concerns voiced about intensive forest management is that harvest practices fragment the landscape into patches of habitat that are unusable for individual organisms or sub-populations. "Connectivity" refers to the arrangement of patches on the landscape and the ability of organisms to use those patches (see reviews by Lindenmayer, 1994 and Simberloff et al., 1992). If a given species of wildlife cannot travel between forest patches, then those patches are considered disconnected. Since many organisms use a variety of patches on the landscape, maintaining connectivity between them is considered essential. This indicator attempts to account for a land of connectivity by maintaining corridors of unlogged forests.

Box D: Applicability to Different Landowners. Explain any differences:

This would apply to all landowners with aims to conserve ecological connectivity of the landscape. Connectivity (but not necessarily corridors) is vital to conservation of populations.

Box E: Overlap:

CCFM: R7, 1.1.4

Notes: The issue of connectivity is multi-scaled and applying to all scales depending on the mobility of individual organisms. For example, some birds and bats migrate through North America and beyond to South America and Asia. Wolves and Grizzly bears have been shown to disperse throughout the intermountain west. Pine marten move between patches of mature confer habitat at the forest management unit level. Thus all spatial scales apply. Connectivity has been best studied at the level of study area and smaller. Certainly connectivity can be accounted for in the management of these scales. It is more difficult at regional and continental scales, but some groups are attempting to do so (i.e. Project Wildlands).

Notes: There is little information for forestry on that gives predictive value to a particular amount of forested corridors (or level of connectivity) on the landscape. Thus for the present, presence of unlogged corridors have little predictive value. For the same reason, they may also have little diagnostic value

Notes: This is a structural measure of the landscape. The key function is connectivity. The debate over this indicator concerns the relation of structure to function.

Box I: Underlying Concepts:

Connectivity of landscapes depends on the spatial distribution of habitats across a landscape as well as the scale at which organisms interact with landscape pattern (Merriam 1984, Noss 1991). The extent to which corridors are actually used by animals is influenced by a number of inter-acting factors (Lindenmayer, 1994a) including:

• 1. The particular species targeted for conservation;
• 2. The attributes of the corridors themselves, such as width and length and vegetation cover;
• 3. The suitability of habitat in the area surrounding corridors;
• 4. The spatial location of corridors in the landscape (e.g. on gullies vs. ridges);
• 5. The type of logging operations and their intensity and pattern in areas surrounding corridors;
• 6. The impacts of edge effects such as windthrow; and,
• 7. The value for fauna of patches connected by corridors.

The basic question is whether or not animals use corridors (or other specific landscape patterns) when moving across the landscape. The answer to this question is again not clear and seems to depend very much on the species. Certainly animals tend to find some patches inhospitable, in most cases large homogeneous areas. In many cases it is clear that animals need a variety of landscape elements to provide for a range of needs that vary in space and time. In a study of dispersing foxes, the animals' movements did not show any correlation to landscape pattern (Storm et al., 1976). The only common pattern observed was that the animals tended to maximize their distance from human habitation. Some animals make extensive use of corridors for much of their movement ( e.g., skunks use hedgerows and mink use stream valleys). Others use corridors on a seasonal basis (e.g.,. wolves use frozen streams for travel). Also, landscape elements often are used to define boundaries between territories.

The exact specifications for connectivity are not well known. Most connectivity-related research has been done in predominately agricultural rather than forested landscapes. Furthermore, it is difficult to extrapolate from individual species connectivity requirements to general rules. However, it is known with certainty that connectivity is important for the survival of populations.

The maintenance of connectivity is important in managed forests where harvesting has the potential to eliminate species from logged areas and fragment and isolate those populations which remain in uncut areas. The idea of connectivity covers features such as exchanges of individuals between sub-populations in a meta-population and the role of sub-optimal habitat (which may or may not be logged) in maintaining links with optimal habitat for particular species.

Connectivity and corridors are often confused. While connectivity is known to be important, the role of corridors in assuring connectivity is not well understood. Corridors assist the movement of animals through otherwise sub-optimal habitat as well as between valued habitat patches. They also provide habitat for resident populations, which may re-colonize adjacent logged and regenerating areas. Corridors may also facilitate continuity between sub-populations in a meta-population, and allow previously unexploited habitat to become available.

Corridors may also have some disadvantages. Corridors may help spread deleterious genes, weeds, pest animals, diseases and fires and act as population 'sinks' (Simberloff et al., 1992). It should be pointed out that such potential disadvantages have rarely been demonstrated.

Box J: Relevance to Sustainable/Unsustainable Management:

The maintenance of viable populations of native species is generally considered to be fundamental component of sustainable forest management (at a forest management unit scale). Fragmentation has been called the greatest worldwide threat to biodiversity. Certainly we know that habitat loss is not the only issue, rather the key measure is unfragmented habitat. Unfragmented habitat can and should be considered in land management planning.

Box K: Measurement Methods:

There are a number of measurement methods available to assess landscape fragmentation.

Box L: Data Required :

See test of indicator CCFM 1.1.4 – Level of fragmentation and connectedness for forest management ecosystems.

Box M: Data Used for the North American Test :

See test of indicator CCFM 1.1.4 – Level of fragmentation and connectedness for forest management ecosystems.

Box N: Example Results:

See test of indicator CCFM 1.1.4 – Level of fragmentation and connectedness for forest management ecosystems

Box O: Assessing the Practicality:

Because the use of unlogged corridors is so variable, it is important to identify explicitly the goals of a network of wildlife corridors. For example, the spatial arrangement of a corridor network may be different if the goal is to provide areas of linear retained habitat rather than promote the movement of organisms through the landscape (Lindenmayer, 1994a). Moreover, given the constraints which typically apply in timber production forests, it may not be possible to design corridor systems that conserve all of those species that are vulnerable to the effects of timber harvesting. Therefore, corridors should be used in tandem with, and not as a substitute for, other conservation strategies such as the retention of permanently protected areas and modified logging practices.

Box P: Assessing the Information Value :

N/A

Box Q: Overall assessment :

Rejected

This indicator has important conceptual underpinnings, but the concept of connectivity is confused with the presence or absence of forested corridors. While forested corridors many be part of a sustainable forested landscape, they are not necessarily so. The concept of connectivity is better addressed under the indicator CCFM 1.1.4 – Level of Fragmentation and Connectedness of Forrest Ecosystem Components.

Box R: Did you rewrite or revise to a new indicator. If so what?

Merged with CCFM 1.1.4 – Level of Fragmentation and Connectedness of Forest Ecosystem Components.

Box S: References :

• Lindenmayer, D. B. 1994. Wildlife corridors and the mitigation of logging impacts on fauna in wood production forests in south-eastern Australia: a review. Wildlife Research 21:323-340.
• Franklin, J. F. and R. T. Forman. 1987. Creating landscape patterns by forest cutting: ecological consequences and principles. Landscape Ecology 1:5-18.
• Merriam, G. 1984 . Connectivity: a fundamental ecological characteristic of landscape pattern. Pages 5-16 in J. Brandt and P. Agger, editors. Proceedings of the First International Seminar on Methodology in Landscape Ecological Research and Planning. Theme I: Landscape Ecological Concepts ,volume 1. Roskilde University Centre Book Company, Roskilde, Denmark
• Noss, R. F. 1991. Landscape connectivity: different functions and different scales. Pages 27-39 in W. E. Hudson, editor. Landscape linkages and biodiversity . Island Press,Washington, D.C., USA.
• Simberloff, D.J. Farr, J. Cox, and D. Mehlman, 1992. "Movement Corridors: Conservation Bargains or Poor Investment?" Conservation Biology 6(4):495.