The Conservation Lands System (CLS) is considered the backbone of the Sonoran Desert Conservation Plan (SDCP). The CLS was constructed based on the science of the SDCP with participation and oversight by the SDCP Science Technical Advisory Team and according to the most current tenets of conservation biology and biological reserve design. The five tenets of the CLS are to:

• Perpetuate the comprehensive conservation of vulnerable species;
• Retain those areas that contain large populations of focal vulnerable species;
• Provide for the adjacency and proximity of habitat blocks;
• Preserve the contiguity of habitat at the landscape level; and
• Retain the connectivity of reserves with functional corridors.

The collective application of these individual tenets produced a CLS that retains the diverse representation of physical and environmental conditions, preserves an intact functional ecosystem, minimizes the expansion of exotic or invasive species, maximizes the extent of roadless areas, and minimizes fragmentation.

Along with the CLS map, the CLS includes an associated set of open space preservation guidelines for development projects that must go through the rezoning process or some other discretionary action. If a landowner develops on their property and does not request a higher density zoning, then the CLS does not take effect.

If for some reason the landowner exceeds the developable percentage allowed, CLS guidelines state that land must be purchased off-site to off-set the disturbance of lands that would otherwise be preserved. The off-site mitigation guidelines call for a specific purchase to disturbance ratio depending on the CLS category. Off-site mitigation ratios are as follows:

• Biological Core Management Areas: 4:1 ratio when disturbance is greater than 20% of the property.
• Special Species Management Areas: 4:1, when disturbance is greater than 20% of the property.
• Multiple Use Management Areas: 2:1, when disturbance is greater than 35% of the property.

These guidelines are instrumental to building a robust open space preserve system in Pima County to ensure that the regional health of the desert is maintained and enhanced.

The Coalition successfully works with private property owners to apply Conservation Lands System guidelines to their projects. This largely consists of the inclusion of contiguous natural open space on their properties, and occasionally mitigation through the off-site set-aside of other parcels of land.

The CLS was in part based off the work of Dr. William Shaw, who chaired the SDCP Science Technical Advisory Team. Dr. Shaw’s 1986 report Critical and Sensitive Wildlife Habitats of Eastern Pima County is credited as the first effort in Pima County to incorporate considerations for wildlife, wildlife habitats, and wildlife movement corridors. The report includes the “Bunny Map” below.