ForestERA Data Layer Overview - Mexican Spotted Owl Management Guidelines

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ForestERA Data Layer Overview - Mexican Spotted Owl Management Guidelines

Description

This is a layer representing the extent of land on the western Mogollon Plateau that is predicted to fall under the legal guidance of the Mexican Spotted Owl (Strix occidentalis lucida) management guidelines. The layer was built using ForestERA vegetation layers and the definitions of Mexican Spotted Owl habitat outlined in the management guidelines for that species (USFWS 1995). The layer has a resolution of 90m (0.8 ha or 2 acres).

Purpose

This data layer was created as part of the ForestERA project to support landscape-scale forest restoration planning efforts by a broad group of stakeholders including federal and state agencies, academic institutions, and non-governmental entities. These data are intended for regional analyses over spatial extents on the order of tens to hundreds of thousands of acres, and were not developed for use at finer spatial scales, although they may be useful for some applications at finer scales.

Development

This layer was developed using the ForestERA dominant overstory vegetation layer, a slope layer derived from a United States Geological Survey digital elevation model (DEM), a layer depicting specially designated protected areas (roadless areas, wilderness areas, and national parks and monuments ) obtained from the Arizona Land Resource Information System (ALRIS), and a layer identifying designated Mexican Spotted Owl Protected Activity Centers (PACs) obtained from the United States Forest Service.

The layer is a prediction of the extent of the landscape that falls under the legal guidelines for management of Mexican Spotted Owl habitat. Habitat areas are defined as being either “protected habitat”, or “restricted habitat”. The legal management guidelines for each of these designations are outlined in an official document (USFWS 1995). Protected habitat includes Mexican Spotted Owl PACs, areas of mixed-conifer or pine-oak vegetation on slopes greater than 40%, and areas of mixed-conifer or pine-oak vegetation in specially designated protected areas. Restricted habitat includes all other areas of mixed-conifer and pine-oak habitat. We were unable to obtain data layers that identified past management actions or tree size. Thus, areas that had been logged in the past 20 years, and areas that did not contain enough large trees were not eliminated from the habitat designations.

Two additional rules were used to clean the map. First areas identified as mixed-conifer in the ForestERA vegetation map, but occurring above 9500 ft, were eliminated. These areas are actually covered by spruce-fir vegetation, which is not included in the management guidelines. There is very little spruce-fir on the western Mogollon Plateau, and so the ForestERA layer does not distinguish spruce-fir from other mixed-conifer. Seconsly, any isolated patches of habitat that covered less than 20 acres were eliminated, as these areas were considered too small to fall under the management guidelines.

Accuracy Assessment

As this layer represents management definitions, rather than specific habitat designations, no true accuracy assessment is possible. We refer readers to the accuracy assessment for the ForestERA dominant overstory vegetation layer and the ForestERA slope layer for information on their accuracy. The accuracy of the PAC layer and the specially designated protected area layer are assumed to meet the accuracy requirements of the agencies that created them.

Sources of errors

Some areas of protected and restricted habitat are likely to be slightly overestimated since we did not have information on tree size nor management history, which might have eliminated some areas from consideration under the management guidelines. However, the vegetation layer tends to underpredict both pine-oak and mixed-conifer vegetation, so there is likely some general underprediction of habitat across the entire study area.

Recommendations

We recommend that this layer be used at a minimum resolution of 90m (0.8 ha or 2 acres) for purposes of analysis and display. However, ForestERA data layers were not designed for analyses at the level of individual pixels, and uncertainty in the data will generally decline over greater spatial extents. Therefore, we recommend using larger analysis units, with groupings of at least 50 cells (40 ha or 100 acres). Finally, we reiterate that ForestERA data layers were developed for the purpose of regional landscape-level planning, and we suggest that the analyses be applied over spatial extents of tens to hundreds of thousands of acres. We recognize, however, that this layer may be useful for analyses over smaller spatial extents depending on the type and purpose of those analyses.

Literature Cited

U. S. Fish and Wildlife Service (USFWS). 1995. Recovery plan for the Mexican Spotted Owl (Strix occidentalis lucida). U. S. Fish and Wildlife Service, Albuquerque, New Mexico.