ASSESSMENTS

* Natural Diversity Database

* Terrestrial Vertebrates Restricted to the Sierra Nevada

Management Strategy

* SNEP Significant Areas Inventory

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The GAP uses land-management classes as a coarse measure for assessing the viability of plant communities. Communities that fall in lands allocated to certain extractive uses are likely to be more vulnerable than those in nature reserves, for example. Five ownership/management classes, based on fire policy and on potentials for development, timber harvest, and grazing were used for assessments:

Class 1: Public or private lands formally designated for conservation of native biodiversity. Development, grazing, and timber harvest are excluded. Examples include national parks, research natural areas, and Nature Conservancy preserves.

Class 2: National forest land that is generally managed for natural values but not formally designated for conservation. Development and grazing are excluded, and timber harvest is generally excluded.

Class 3: Public land that is generally managed for natural values, is currently classed as suitable for timber harvest, and may be grazed. Examples include grazing allotments in national forest wilderness, and Bureau of Land Management wilderness areas.

Class 4: Other public lands not included in Classes 13, mainly multiple-use lands.

Class 5: Private lands other than those in Class 1.

Use of these management classes as surrogates for biodiversity vulnerability is subject to many exceptions, and generalization is implicit. We do not intend to imply that timber harvest, grazing, or other activities are necessarily detrimental to biodiversity. Further, although the databases used in this analysis are the most comprehensive ever assembled for the region, producing the maps and analyzing the data at this scale require assumptions and simplifications, which need to be verified on the ground for local accuracy.
The GAP mapped 15% of the Sierra Nevada region as Class 1 lands. Yosemite, Sequoia, and Kings Canyon National Parks account for most (89%) of this area. These parks are an important source of large, continuous protected habitat. Nearly half of the total units grouped as Class 1 lands, however, are small parcels, less than 100 acres, meaning that they may be unable to contribute to landscape-level ecosystem functions (migration, dispersal, metapopulation maintenance, animal habitat quality, recruitment). An additional 7% of the Sierra Nevada region is in Class 2 lands.
By adding the areas in Classes 35, we estimate that about 80% of the region, or 89% of the vegetated land, is available for grazing. Similarly, summing Classes 45, we find that about 57% of the land area is available for timber harvest.
The ownership of Sierran plant communities varies in a way that reflects the concentration of private lands at lower elevations and of National Park Service lands in the central and southern portions of the range. Many of the foothill plant community types fall largely within private lands, notably non-native grassland (88% of the mapped distribution on private lands), valley oak woodland (98%), blue oak woodland (89%), interior live oak woodland (71%), and foothill pineoak woodland (82%).
A number of widespread community types occur disproportionately on national forest lands, notably low sagebrush scrub (79%), rabbitbrush scrub (93%), mountain mahogany woodland (94%), mixed montane chaparral and montane ceanothus chaparral (73%), bush chinquapin chaparral (85%), cismontane juniper woodland (86%), northern juniper woodland (85%), aspen (89%), east-side ponderosa pine (76%), Jeffrey pine forest (75%), Jeffrey pinefir forest (80%), western white pine forest (75%), whitebark pinelodgepole pine forest (86%), and alpine dwarf scrub (99%). Foxtail pine forest is the only type whose distribution falls mainly within the national parks (77%).