Chapter 7: Methods for GIS Data Manipulation, Analysis ...

Chapter 7: Methods for GIS Data Manipulation, Analysis, and Evaluation

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OVERVIEW

This chapter details the methods that the team used to 1) evaluate lands within the study area, 2) delineate Conservation Focus Areas (CFAs), and 3) prioritize individual, privately owned land parcels for protection. The chapter also describes the team's methods for assessing and evaluating threats to the study area's ecological integrity.

As noted previously, the project's analysis consists of two main phases operating at two different scales.

? Phase One: Regional Scale ? In this phase, the team analyzed the entire study area and ranked the matrix of lands as low, medium, high, or highest priority. The team delineated CFAs around larger clusters of high and highest priority lands.

? Phase Two: Parcel Scale ? In the project's second phase, the team analyzed privately owned parcels within the CFAs and ranked those parcels in order of their conservation importance.

For organizational and presentation purposes, this chapter describes the methods of each phase separately. It is important to note, however, that Phase Two is intrinsically linked to Phase One. In addition, the basic methodological approach for each phase is very similar. Namely, the team uses a straight-forward geographic information systems (GIS)-based analysis to spatially represent important ecological features, weight those features based on their relative ecological importance, and consolidate the individual weights to determine the relative conservation priority of landscapes and parcels within the study area. The team did not weigh threats but spatially represents as many of them as possible to depict their relationship to the CFAs.

PHASE ONE ANALYSIS: CFA DELINEATION AND PRIORITIZATION

There are five main steps in this phase of the analysis. Figure 7.1 summarizes the five steps of this analysis, which are described in detail in the text that follows.

Figure 7.1: Basic steps in Phase One Analysis

1.

Develop conservation drivers to represent project objectives spatially.

2.

Spatially represent and weight conservation drivers.

3.

Use raster grids to conduct overall prioritization analysis.

4.

Delineate Conservation Focus Areas (CFAs).

5.

Rank the CFAs according to ecological, spatial, opportunity, and feasibility criteria.

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STEP 1: DEVELOP CONSERVATION DRIVERS

In order to incorporate the project's goals and objectives directly into the GIS-based analysis, the team developed a tool that it termed a "conservation driver." Simply put, a conservation driver is a spatial representation of a project objective. In most cases, the language describing both the objective and the driver is very similar. It is important to note, however, that the two concepts are different. An objective consists of an action-oriented purpose for the project. A conservation driver is the spatial representation of that objective, a mappable entity that can be manipulated and analyzed using GIS. In other words, an objective is an idea and a driver is that idea spatially delineated on the landscape.

An example from the project helps illustrate both the close connection and the important difference between objectives and drivers. One of the project's objectives is to Conserve Natural Areas that Exhibit a High Degree of Integrity and Resiliency. The team uses presettlement vegetation as the corresponding driver to measure and map intact and resilient natural areas. For every project objective, the team developed a corresponding conservation driver.1 Table 7.1 summarizes the project's conservation drivers and their relationship to the project's mission, goals, and objectives.

1 Note that some drivers support more than one objective, and that some objectives are expressed through more than one driver. For each objective, however, there is a primary driver that spatially expresses the objective more directly and effectively than others.

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Table 7.1: Mission, Goals, Objectives, and Conservation Drivers

Mission: To guide future work and investment of the Grand Traverse Regional Land Conservancy

in the Manistee River watershed, this project will identify areas of high conservation value and,

within those areas, prioritize privately owned land parcels for protection efforts.

Goals

Objectives

Conservation Drivers

Conserve Areas of High Ecological Importance

Protect hydrologic integrity of the upper Manistee River watershed

Groundwater accumulation

Conserve wetland ecosystems

Wetlands

Conserve riparian ecosystems

Riparian ecosystems

Maintain biodiversity

Element occurrences

Protect a diversity of local ecosystems Rare landtype associations

Conserve natural areas that exhibit a high degree of integrity and resiliency Pre-settlement vegetation

Promote Spatial Integrity of the Landscape

Conserve unfragmented landscapes

Large tracts of unfragmented natural areas

Promote the expansion and integrity of Expansion and integrity of

existing protected areas

existing

protected lands

Target large land parcels

Parcel size*

Identify and Delineate

Analyze threats and their sources and, Sources of threats**

Threats to Ecological

when possible, map those sources

? Development

Systems and Processes

? Oil and Gas Drilling

? Incompatible Logging

? Invasive Species

? Road Development

? Off-Road Vehicle Use

? Fire Suppression

? Dams

*Not a weighted conservation driver but used in parcel analysis and prioritization.

**Not weighted or used on CFA or parcel prioritization.

STEP 2: SPATIALLY REPRESENT & WEIGHT CONSERVATION DRIVERS

As the second step toward prioritizing lands within the study area for protection, the team spatially represented each driver and assigned weights to each driver according to its relative conservation value. The team conducted these activities using geographic information systems (GIS).

The wetlands driver provides a simple example of how the team used conservation drivers to help prioritize lands within the study area. For this driver, the team analyzed GIS data that

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depicted the location and extent of wetlands within the study area. The team assigned a weight of 10 points to those areas that contained wetlands and 0 points to all other lands in the study area. Table 7.2 summarizes the basic analysis and associated weights the team used for each conservation driver.

Table 7.2: Basic analysis and weighting scheme for the conservation drivers

Conservation

Basic Analysis

Weighting Scheme

Driver

Groundwater

Examined groundwater accumulation ? Areas with accumulation levels

Accumulation

data and classified areas according to

greater than or equal to 2 SD: 10

standard deviation (SD) from

points

statewide mean.

? Areas with accumulation levels 1 SD: 5 points

? All other areas: 0 points

Wetlands

Analyzed as present or absent.

? Wetlands: 10 points

? Non-Wetlands: 0 points

Riparian

Used two different buffer distances to ? Lands within 50m of all streams and

Ecosystems

prioritize riparian areas.

lakes: 10 points

? Lands between 50 and 300m of

river's mainstem: 5 points

? Lands outside those buffers: 0

points

Element

Calculated point density of element ? Areas with occurrence density > 2

Occurrences

occurrences and reclassified results

SD: 10 points

using standard deviation (SD) from ? Areas with occurrence density

mean.

between < 2 and > 0 SD: 5 points

? Areas with occurrence density less

than or equal to 0 SD: 0 points

Rare Landtype

Analyzed according to two thresholds: ? LTAs passing both rarity and study

Associations

the overall rarity of LTA within the

area representation thresholds: 10

ecoregion and the percentage of that

points

rarity contained within the study area. ? LTAs passing only one threshold: 5

points

? All other LTAs: 0 points

Pre-settlement

Analyzed the overlap between

? Highest priority areas of overlap: 10

Vegetation

estimated 1800 land cover and

points

present day land cover and examined ? High priority areas of overlap: 5

areas exhibiting cover resembling pre- points

settlement vegetation.

? All other areas: 0 points

Large Tracts of Examined contiguous natural areas ? Areas > or equal to 1,000 acres and

Unfragmented

(not bisected by main roads) and

centroid is > or equal to 500m from

Natural Areas

analyzed them according to relative

roads: 10 points

size and distance of centroid from

? Areas > or equal to 1,000 acres and

nearest road.

centroid is < 500m from roads: 5

points

? All other areas: 0 points

Expansion and

Used two different buffers ? expansion ? Lands within the integrity buffer and

Integrity of Existing and integrity ? to prioritize private

880 m or less from protected lands:

Protected Lands lands within the study area.

10 points

? Lands within expansion buffer or

within the integrity buffer but > 880

m from protected areas: 5 points

? All other lands: 0 points

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