An ecosystem-based approach protects forest functioning at all scales through time as the first priority, and then seeks to sustain, within ecological limits, a diversity of human and non-human uses across the forest landscape. In other words, ecosystem-based approaches focus first on what to leave and then on what can be taken without damage to ecosystem functioning.
Where timber extraction is determined to be an appropriate activity, ecologically responsible timber management means that plans and activities are developed and carried out in ways that protect, maintain, and restore (where necessary) a fully functioning forest ecosystem at all temporal and spatial scales. Forest composition, structures, and functioning are maintained, from the largest landscape to the smallest forest community, in both short and long terms. |
AN ECOSYSTEM-BASED APPROACH TO FOREST PROTECTION AND USE: DEFINITION AND SCIENTIFIC RATIONALE
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An ecosystem-based approach recognizes that a forest ecosystem is a continuum in time and in space. In other words, over time, a forest ecosystem is not static and unchanging. Natural disturbances constantly modify forest ecosystems as time passes. However, unlike disturbances from integrated forest management and other forms of conventional management, natural disturbances serve to maintain forest functioning and provide biological legacies (e.g. dead trees) that connect one forest successional phase to another. In a natural forest ecosystem, the most common disturbance or agent of change is the death of an individual tree or small groups of trees.
A forest ecosystem is also a spatial continuum. In other words, forests are interconnected, interdependent clusters of ecosystems, from patches of different soil types within a 4 hectare (10 acre) forest stand to a watershed of 500,000 hectares (1.2 million acres) or more. Understanding that a forest ecosystem is a continuum through time and space reinforces the wisdom that what we do to one part of the forest we do to all parts of the forest. Two important concepts are encompassed within the understanding that forest ecosystems are spatial and temporal continuums: forest landscapes and forest stands/forest patches.
The Forest Landscape
The forest landscape is the large-scale view of a forest. When industrial timber managers use the term “forest landscapes,” they are usually concerned with scenery and visual impacts. In the context of an ecosystem-based approach, however, a forest landscape is a mosaic of interconnected, interdependent stands or patches that are repeated in a pattern across the larger landscape. This pattern has both spatial and temporal components.
An ecosystem-based approach requires that all planning and activities begin at the regional/landscape level. When planning for human use, landscape level decisions are made for watersheds of small to moderate size (less than 5,000 hectares to about 50,000 hectares, or 12,000 to 125,000 acres). In sub-regional or regional planning processes, forest landscape level considerations are expanded to large watersheds encompassing hundreds of thousands of hectares/acres.
In planning and carrying out forest uses, particularly timber management, many people tend to focus on small forest parcels. This is a result of our limited spatial view, short time frames, and cultural conditioning. In contrast, an ecosystem-based approach requires that all planning and activities start at the landscape level. The character and condition of the forest landscape dictate what is ecologically possible at the stand level.
The character of a forest ecosystem refers to how a forest works, from the landscape level to the stand or patch. For example, forests that have frequent fires have a different character than forests where wind and root decay are the primary agents of disturbance. Some forests are characterized by steep slopes, shallow soils, and well-defined drainage patterns, while other forests have gentle slopes, cold soils, and diffuse drainage patterns.
Forests of a different character will have different composition and structures, and therefore differences in how they function. Different composition, structures, and functioning lead to different kinds of ecological limits to human use. Ecological limits are natural factors or processes that are easily damaged or degraded if modified by human uses. For example, steep and/or wet slopes impose ecological limits because, if disturbed, they are likely to erode, causing problems like soil loss and siltation of streams. Cold soils are an ecological limit because nutrient cycling occurs in shallow organic layers which may be easily damaged by many types of human activities.
The condition of a forest describes how human uses have modified forest functioning from the landscape level to the stand or patch level. Conventional timber management frequently results in negative impacts, like fragmentation, loss of old growth, and soil degradation. An ecosystem-based approach protects forest composition and structure and respects the ecological limits of forests to various human uses. By respecting ecological limits ecosystem-based approaches avoid degradation of short- and long-term forest functioning.
Ecological limits to human use are determined by describing and interpreting the character and condition of, first, the forest landscape, and then the forest stand or patch.
Forest Stands/Forest Patches
Forest stands or forest patches refer to the ecosystem scale at which a relatively homogenous forest unit can be identified. The composition, structure, and ecological functions within a stand are similar enough that an ecologically responsible forest use prescription can be applied uniformly within the stand, without encountering changes in ecological parameters that may produce unexpected or undesirable results.
In conventional forestry, “stands” have largely been defined by narrow timber characteristics, which were in turn driven by short-term economic variables. However, in order to plan and carry out ecologically responsible forest uses within an ecosystem-based approach, stands must be defined in relation to whole ecosystem factors that are required to maintain fully functioning forests at the landscape and stand levels. In other words, the boundaries of a stand are not determined by rigid human management criteria such as timber size and timber quality, but by the full spectrum of ecosystem parameters that have been shaped by natural disturbance patterns and that reflect the movement of energy, nutrients, water, and animals into and out of a particular ecosystem.
Human scales are closest to forest scales at the stand or patch level. For example, the stand or patch level is the scale where visible human modification occurs. However, an ecosystem-based approach must always consider that what occurs at the stand or visible scale will also have impacts on a variety of other scales, from the large landscape to the microscopic.
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Source : Ecosystem-based Landscape Plan for the Slocan River Watershed. Silva Forest Foundation.
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