How To Use the CLN

The establishment of upland habitat goals for the San Francisco Bay Area is a big step forward for strategic biodiversity conservation. Those interested in applying the goals are encouraged to review the approach used by the Upland Habitat Goals Project to understand how its findings are best translated to on-the-ground conservation. A few key guidelines followed by some specific questions to ask are provided here.  Chapter 11: Interpreting the Conservation Lands Network of the report provides a full discussion of how to interpret the Conservation Lands Network to guide conservation actions.

Key Guidelines for Interpreting the Conservation Lands Network:

Key Questions to Ask to Interpret the Conservation Lands Network (CLN):

CLN Explorer provides valuable information about a selected area, but it does not provide a definitive picture of its conservation value; users can meet the intent of the Conservation Lands Network in ways not specified by the CLN. Conservation practitioners must rely on professional judgment and consultation with the conservation community to weigh the quantitative information in CLN Explorer, the Biodiversity Portfolio Report, and any additional GIS analyses against qualitative information on the location, feasibility, and viability of the selected area for biodiversity conservation. Other open space values supported by the selected area should also be considered.

The following questions should be asked when reviewing the report results.  The numbers correspond to those on the sample Biodiversity Portfolio Report to the right.

1. Does all or part of the selected area fall within the Conservation Lands Network? Is part or all of the area chosen within the Areas Essential for Meeting Biodiversity Goals, Important Areas, Fragmented Areas, or Areas for Further Consideration?

This can be determined by reviewing the map in the Biodiversity Portfolio Report as well as the Conservation Lands Network Category section (see the Biodiversity Portfolio Report to the right, #1). Areas falling within the Essential Areas will generally be strong candidates for biodiversity conservation, but this does not preclude further investigation. Because they do not have the highest-value conservation targets, the occurrence of Important Areas and Areas for Further Consideration in a selected area may allow for more flexibility in the CLN configuration depending on the results of site visits and biological surveys. Fragmented Areas are discussed below.

2. If the selected area falls within the Conservation Lands Network, why was it selected?

a. Is the selected area adjacent to existing protected lands? The conservation practitioner can determine if the selected area is adjacent to protected lands by reviewing the map on CLN Explorer, the map included in the Biodiversity Portfolio Report, or the section titled “Protected Land Within Selected Area” (#2a). If there are no protected lands within the selected area, this section of the report will show the distance to the nearest protected land so the user can evaluate the potential for making a connection to protected areas.

Because Marxan automatically adds to the CLN those hexagons with 10% or greater area in protected lands, it is possible that the main conservation value of an area within the CLN is its adjacency to an existing protected area. The user can review the Biodiversity Portfolio Report to determine whether there are other conservation targets that also contributed to its selection.

b. What are the vegetation types (coarse filter targets) within the selected area? Areas with large swaths of Rarity Rank 1 vegetation types are almost guaranteed to be in the CLN because of the 90% conservation goal. Areas with Rarity Rank 2 vegetation types are more likely to be included in the CLN because of the 75% conservation goal. If the property is all Rarity Rank 3, its inclusion is likely attributable to other factors such as proximity to protected lands, conservation suitability, and/or the presence of fine filter targets. The section of the Biodiversity Portfolio Report called “Conservation Targets / Coarse Filter Conservation Targets” (#2b) lists each of the coarse filter targets within the selected area, along with their Rarity Rank and contribution to the landscape unit acreage goals.

c. What are the fine filter targets within the selected area? The presence of high-value fine filter targets such as particular plants or animals with 90% or 75% goals (e.g., Alameda Whipsnake or Northern Spotted Owl) may be the reason an area is in the CLN. High concentrations of ponds, which have 75% or 50% conservation goals (depending on the landscape unit), also may drive an area’s inclusion in the CLN. The section of the Biodiversity Portfolio Report called “Fine Filter Targets” (#2c) lists each fine filter target in the selected area and its contribution to the landscape unit goals.

d. Are there Priority 1 or 2 streams within the selected area? All streams are conservation targets and included in the CLN. Lands encompassing and immediately adjacent to streams, especially Priority 1 and 2 streams, are of high conservation value. If a Priority 1 or 2 stream occurs within the selected area, the Biodiversity Portfolio Report includes a Stream Conservation Targets section (#2d). The user can determine which streams are in or near a selected area by turning on the Stream Conservation Targets data layer in CLN Explorer.

e. What is the Conservation Suitability Index? The Conservation Suitability Index is a composite indicator of ecological integrity based on parcelization, distance to paved roads, and human population density. Areas with high Conservation Suitability are more likely to be included in the CLN. The Biodiversity Portfolio Report displays the area’s Conservation Suitability along with a description of the score as high, moderate, low, or poor. (#2e). Where there are fewer small parcels and roads and the population density is low, Conservation Suitability is high – as indicated by a low number for the Conservation Suitability Index.

3. Does the selected area include Fragmented Areas with Urban, Rural Residential, or Cultivated Agriculture uses nearby?

Fragmented Areas are the result of the erasure of Urban, Rural Residential, and Cultivated Agriculture lands (collectively, Converted Lands) from the final Marxan configuration of the CLN, which leaves only the location of the conservation target and/or protected area in the CLN (Chapter 3, Figure 3.9). Fragmented Areas are generally of lower conservation suitability, but are included in the CLN where high conservation value (Rarity Rank 1 or 2) conservation targets (coarse or fine filter) are present and when these areas are needed to meet the 90% or 75% conservation goals. Because Fragmented Areas require more detailed treatment than is possible at the scale of the CLN, the conservation practitioner must not only determine whether the targets exist as shown on the map, but also evaluate the viability of the target if the surrounding land uses are incompatible. Site visits and biological surveys are required to determine the conservation suitability of these Fragmented Areas. The Conservation Lands Network Category of the Biodiversity Portfolio Report (#3) shows the acreage of Fragmented Areas and Converted Lands (Cultivated Agriculture, Rural Residential, and Urban) within the selected area.

4. If the selected area falls outside of the Conservation Lands Network, how would its conservation contribute to meeting the goals?

If the selected area is not within the CLN, there are several approaches for evaluating its potential contribution to meeting the goals. Reviewing CLN Explorer and the Biodiversity Portfolio Report (as described above, for coarse and fine filter conservation targets, priority streams, conservation suitability, and proximity to protected lands) can help assess the area’s conservation values. Do roads or Urban, Cultivated Agriculture, or Rural Residential land uses impact the viability of the targets?

Additional information about lands outside of the CLN can be gleaned from CLN Explorer and the Biodiversity Portfolio Report by asking the following questions:

a. How many times was the selected area selected by Marxan for inclusion in the Conservation Lands Network? The number of times the planning unit(s) underlying the selected area was (were) selected by Marxan is another indicator of conservation value. Areas Essential to the Conservation Goals were selected by Marxan 16 to 20 times out of 20 runs; Important Areas were selected 11 to 15 times. Therefore, planning units selected closer to 11 times have a higher potential conservation value, based on the data used to identify the CLN. The figure below illustrates how the CLN Explorer ID tool can be used to find the number of times a planning unit was selected by Marxan.


b. Are there additional datasets not included in the Upland Habitat Goals Project analysis that might increase the conservation value of the selected area? The project used the best available data but was not able to seek out smaller datasets for all of the conservation targets. Existing data or site surveys of the selected area might reveal the presence of high-value conservation target species. If a high-value target is found on the area, the conservation practitioner must determine whether a connection can be made to protected lands or other lands within the CLN, and if not, whether the target will be viable without such a connection in light of the surrounding land uses.

c. If the area were to be conserved, how would the configuration of the Conservation Lands Network change? Because there may be many options to meet the goals in common vegetation types (Rarity Rank 3 with a 50% conservation goal), lands not included in the CLN can be considered if they contain conservation targets that would contribute to meeting the goals, are ecologically intact or could be restored, and can be connected to protected lands or other lands identified in the CLN. The figure below is an excerpt of a Biodiversity Portfolio Report for a property proposed for conservation that is not entirely within the CLN. The report shows that the property is adjacent to existing protected lands, and forms a linkage to other Essential and Important Areas. The report also indicates the presence of the rare plant, Mt. Diablo fairy-lantern, and that if the property is conserved, the goal for this species will be met for this landscape unit.