摘要:

A science-based ecosystem management approach requires valid reference points to assess the long-term maintenance of forest systems. Historical range of variability (HRV) in vegetation patterns has served as the initial reference point and has support in the coarse-filter approach to conserving biodiversity (Hunter 1991). The HRV becomes less useful as a reference with increasing human disturbance on the landscape, public aversion to treatments to restore historical states, and continued public expectations for non-historical conditions. The inherent disturbance regime (IDR) is put forward as an alternative or to be used in combination with HRV as a suitable reference point for evaluating long-term maintenance of human-altered ecosystems. The IDR is defined by the types of disturbance; their frequency, intensity, and extent in turn defines the vegetation composition and structure supported over time. Although public expectations for vegetation conditions may differ from historical, these altered states may also be supported by IDR and have long-term maintenance potential. The use of a disturbance reference (IDR) rather than a condition reference (HRV) appears more compatible with the dynamic nature of forests. As an accurate description of historical conditions and disturbance regimes is difficult we recommend that both references be used reiteratively to better refine the other. Increased discontinuity between public expectations for forest conditions and the ability of those conditions to be supported by disturbance regimes may lead to catastrophic disturbance events and a decline in long-term site nutrient capital and biodiversity.

ISSN:1054-9811    

DOI:10.1300/J091v11n01_11

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We utilized the Boise National Forest's Hazard/Risk model, along with fire history records and fire behavior models, to estimate the current and anticipated levels of large wildfires and associated greenhouse gas and particulate emissions based on the forest condition and wildfire regime on the BNF. The model indicated that the forests at greatest risk of large, intense wildfires are the dense pondero-sa pine-Douglas-fir forests that make up over 1.1 million acres on the forest. We conclude that without an aggressive treatment program to reduce large areas of contiguous heavy fuel loadings the forest will be burned at an annual average rate of about 7.5% of the remaining at-risk forest. Using recent fire data to develop average patterns of intensity in wildfires within this forest type, we estimate that emissions will average around 1 million tons of carbon (C) per year over the next 20 years as the bulk of the ponderosa pine forests are burned. An aggressive treatment program featuring the removal of fuels where necessary, and prescribed fire as a means of re-introducing fire to these ecosystems, would result in a 30-50 percent reduction in the average annual wildfire experienced in the dense ponderosa pine forests, a 14-35% decrease in the average annual C emissions, and a 10-31% decrease in particulate emissions. We argue that the most effective way to curb emissions is with an aggressive treatment program linked to a landscape-based ecosystem management plan. This would have the effect of breaking up large contiguous landscape patterns so that fires become more patchy and diverse in their environmental impact, resulting in significantly reduced emissions as well as improved landscape diversity.

ISSN:1054-9811    

DOI:10.1300/J091v11n01_12

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Colorado has long been known for its scenic vistas and majestic mountains. Wildfires which are common in the summer months can significantly impact scenic environments close to the wildfire location. There are also concern as to the health impact to people in towns and cities located on the urban/wildland interfaces where the impact can also include loss of life and property. For these and other reasons, a concerted effort is underway to better understand the implications of these wildfires on areas potentially impacted by smoke.

ISSN:1054-9811    

DOI:10.1300/J091v11n01_13

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor