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Land cover change: Forest loss

Forest conversion measures the loss of forested land cover to developed land cover. The indicator provides a check on our regional success in maintaining forest cover throughout the Puget Sound Basin.

Forested landscapes, as measured by forest cover, provide:

1. habitat functions that support terrestrial species,
2. watershed functions that support freshwater systems, and
3. provisioning and cultural services for humans.

Change in forested lands is monitored using National Oceanic and Atmospheric Administration analysis of satellite imagery to track change from forested land cover, including coniferous, deciduous, and mixed forest classes, to developed land cover using four classes of development intensity, on a five-year basis. Forest cover conversion in the Puget Sound Basin has been consistently measured every four to five years since 1992 with the next results expected in late 2012 for change during the period 2006-2011.

Land cover loss: Riparian vegetation restoration

The riparian vegetation restoration indicator measures the amount of new vegetated cover delivered by restoration projects along riparian corridors. These corridors are a critical component of the Puget Sound ecosystem and the indicator evaluates the effect of direct efforts to improve them. Intact, vegetated riparian corridors are critical for:

1. keeping fresh and marine waters clean and cool,
2. moderating variability in water volume and timing of flow (i.e. flood storage), and
3. as key habitat for myriad terrestrial, freshwater and interface (e.g. salmon) species.

The amount of riparian corridor restored to vegetated cover will be measured through collection of acreage or linear riparian shoreline restoration reported for Puget Sound restoration projects. Riparian restoration efforts are being measured instead of riparian condition due to the difficulty in assessing riparian condition Soundwide and the length of time necessary to call a specific location successfully restored. Although tracking total riparian condition is a much more difficult task than tracking regional forest cover, the initiation and completion of restoration activities are feasible measures. Successful restoration could take many years and measuring its success will require ongoing monitoring. Recent restoration efforts in the Puget Sound Basin have included 19 projects completed from October 2009 to September 2012 to restore riparian vegetation. These projects involved planting and other actions beyond treatment to remove invasive species. A project length was reported for 13 of the projects.

Land development pressure: Conversion of ecologically important lands

The indicator tracks the conversion from vegetated cover to developed cover on undeveloped lands identified as ecologically important and that are under high pressure from development for residential, commercial, and industrial uses. This indicator was developed in 2011 as part of a larger effort to define the ecological importance and development pressure for all parcels within the Puget Sound Basin. Indicator lands—one of four land base types that were defined—include those parcels determined to be ecologically important and under high pressure from development. The other three land base types include:

1. areas determined to be ecologically important under low pressure from development,
2. areas of lower ecologically importance and high development pressure, and
3. areas of lower ecologically importance and low development pressure (Figure 1).

A parcel’s ecological importance was determined using Washington State Department of Ecology, Washington State Department of Fish & Wildlife, and Puget Sound Nearshore Ecosystem Restoration Project data identifying areas of high significance and high integrity with respect to hydrological dynamics, habitat quality, or biodiversity. Areas under high pressure from development included parcels with less than 35% impervious surfaces in private ownership with limited or no regulatory protection.

Because of the coarse scale approach to defining ecologically important lands in the indicator land base, this indicator is appropriately used to identify broad regional trends. This indicator’s results are not intended for use in local decision-making, permitting, or planning.

This indicator provides a regional measure of the effectiveness of local jurisdictions’ efforts to direct growth away from undeveloped ecologically functional areas. Specifically, the indicator provides a measure of the success of local governments in identifying and protecting ecologically significant and intact lands within and outside of Urban Growth Areas, a priority strategy in the Puget Sound Action Agenda.

It is also an indicator, though perhaps a weaker one, of how effectively local jurisdictions are using or incorporating landscape characterization methods, or other ecologically based information, into their land use decision-making.

Land development pressure: Growth in urban growth areas (UGAs)

This indicator tracks the proportion of population growth occurring within urban growth areas. Population growth is used as a surrogate for development activity in the region. Ten-year U.S. Census data are used for this indicator and the analysis will be updated when census data are next available in 2020. In order to generate intermediate measures of population growth distribution and assess progress toward the target, the less precise U.S. Census American Community Survey will be used.

County comprehensive plans designate urban growth areas for high-density urbanization with the intent to guide as much growth as possible to these areas to support regional and local economies, meet residence needs for a growing population, and be concurrent with infrastructure availability. This indicator therefore provides a measure of the effectiveness of land use policies and programs. It also measures the effectiveness of development practices in directing new development activities within existing urbanized areas and reducing land development pressures on rural and resource lands outside of urbanized areas.

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Land cover change: Forest loss

The analysis of progress toward the 2020 target is pending due to lack of data.

Non-federal Puget Sound Basin forest was converted to developed cover at a rate of 2,176 acres per year for the period 2001-2006. Data needed to calculate an updated conversion rate for the period 2006-2011 were not yet available, but are expected in 2013.

Achievement of the 2020 target rate of 1,000 acres converted per year would represent a roughly 50% reduction from the 2001-2006 annual conversion rate, or an 80% reduction from the 1991-2001 conversion rate of 5,048 acres per year. 1991-2001 was a period of unprecedented regional growth that included significant expansion of the developed landscape. Limiting the conversion rate to 1,000 acres per year is an ambitious target that reflects our need to minimize loss of regional forest cover while recognizing that some conversion of forest cover for the purposes of development and infrastructure development is necessary.

Land cover loss: Riparian vegetation restoration

Some progress has been made toward the 2020 target. Habitat data collected by the Puget Sound Partnership on behalf of the Environmental Protection Agency indicate that 19 riparian restoration projects were conducted in the Puget Sound basin from October 2009 through September 2012. However, miles of restored riparian corridors were reported only for 13 projects. In total, at least 76 miles were restored during that time period, or 28% progress toward the 2020 target of 268 miles. It should be noted that riparian corridor restoration prior to October 2009, the baseline reference year, was not counted toward the target.

Land development pressure: Conversion of ecologically important lands

The analysis of progress toward the target is pending due to the lack of data, which will be available in 2013. However, achieving the 2020 target will require reducing the conversion of ecologically important lands to development to just over one-half the rate of conversion observed in 2001-2006.

The five-year baseline rate of land cover change on the indicator land base across all 12 counties in Puget Sound for the period 2001-2006 was 0.28%. Similar analyses will be completed every five years to track change over the periods 2006-2011, 2011-2016, and 2016-2021.

Land development pressure: Growth in urban growth areas (UGAs)

The analysis of progress toward the 2020 target is pending until new data are made available. Based on U.S. Census data from 2000 to 2010, the Puget Sound basin-wide population growth occurring within urban growth areas was 83% (Table 2 in Latest data and maps section). For counties, this indicator ranged from 28-101%. For future analyses of progress, the value derived from the 2000 to 2010 census data will be used as a baseline reference for basin-wide (83%) and county-scale (ranging from 28-101%) population growth distribution.

The 2020 recovery target of 86.5% of population growth occurring within urban growth areas is equivalent to a 3% increase in the proportion of new population growth occurring within all Puget Sound urban growth areas. This target represents an effort to direct more growth to those areas deemed best suited for development, while also respecting that Puget Sound includes very urban as well as very rural counties with very different growth management needs and objectives. Data on the distribution of permits for new development (a proxy for population growth) within five of the 12 Puget Sound counties suggest that the target is achievable.

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Land cover change: Forest loss

The current trends and targets were set using land-cover change information for lands not in federal ownership as determined by the Landsat satellite imaging system. Due to image element limitations, this approach does not capture relatively small land use change, such as clearing for single homes or lot expansion, and therefore only larger events (more than two acres) are reliably captured in these values.

Land cover loss: Riparian vegetation restoration

The sum of the lengths reported for the 13 projects between October 2009 and September 2012 is about 76 miles, which is 28% of the 2020 target. If the median project length were applied to the six projects with no length estimate provided, we would estimate that the total mileage restored in this three-year period at 86 miles, which is 32% of the 2020 target.

Data source

Puget Sound Partnership staff analyzed data for federal fiscal years 2010, 2011 and 2012 primarily from the Washington State Recreation and Conservation Office’s PRISM database and reports of Natural Resource Conservation Service (NRCS) habitat programs.

Land development pressure: Conversion of ecologically important lands

The 2011 indicator land base represents 13% of the total Puget Sound land area (Table 1). As shown in Figure 1, most of the indicator land base lies around the urban fringe, outside of urban growth areas (UGAs) in the Puget Sound lowlands. The parcels that make up the indicator land base often fall along transportation corridors that are also important habitat and hydrological corridors, within the region’s most productive farmlands (e.g. around Mount Vernon and north of Bellingham), and in lowland forested areas to the south and west of the Puget Sound. Although the parcels typically fall outside of areas identified as the highest priority and most suitable areas for growth and development (i.e. urban growth areas), in most cases there are no protective measures in place to direct growth away from these ecologically important areas.

The majority of the land area in Puget Sound (68%) is classified as high ecological importance and low pressure from development. This land base type is primarily made up of publicly owned forest and protected lands, privately owned large scale forest lands, and privately owned protected lands. The remaining 20% of the land area is classified as low ecological importance with high and low development pressure and includes significantly ecologically degraded areas.

A 2011 12-county analysis of land cover change reveals a loss of vegetative cover on 0.28 % of the indicator land base (2,996 of 1,084,785 acres) over the period 2001-2006 (Table 1). This is equivalent to 15% of total vegetation loss in Puget Sound for the period 2001-2006. In contrast, the land area classified as high ecological importance but under low pressure from development only experienced 6% of basin-wide vegetation loss. These preliminary results suggest that protective measures are influencing where development is occurring but it is not yet possible to say how much of the lower conversion rate on low pressure lands is due to protective measures versus suitability for development. The remaining 79% of vegetation loss for the five-year period 2001-2006 occurred on lands classified as low ecological importance, with 50% and 29% of vegetation loss occurring on high and low development pressure lands, respectively.

This analysis suggests that regulatory and other protective measures are directing much of the region’s development away from ecologically important lands. However, with roughly 20% of vegetation loss still occurring on ecologically important lands, there is significant room to improve the degree to which we are directing and concentrating new growth in those areas that are not as critical for maintaining and recovering the health or Puget Sound species, habitats, waters, and people.

Land development pressure: Growth in urban growth areas (UGAs)

Washington population data, based on 2010 U.S. Census data, was used for the baseline analysis of population growth distribution for urban growth areas and rural areas between 2000 and 2010 (Table 1). Basin-wide, 83% of new population growth from 2000 to 2010 occurred within urban growth areas. For individual counties, the proportion of growth occurring within urban growth areas ranged from a low of 28% for Mason and Jefferson counties to highs of 92% and 101% for Snohomish and King counties, respectively.

Data are not currently available to complete a trend analysis of population distribution patterns over the past 10 years. However, the Washington State Department of Commerce has been collecting data on the distribution of permits for new development and a preliminary analysis suggests that growth is increasingly occurring within urban growth areas. For five central Puget Sound counties, the proportion of permits for new development within urban growth areas increased at an average rate of 0.85% per year from 2003 to 2010. Carried out over 10 years, these permit data suggest an almost 10% increase in the proportion of growth going into urban growth areas in central Puget Sound. While permit activity does not correlate exactly to population increase, these reports provide an indication of progress (in a five-county area) toward the 2020 recovery goal of an increasing proportion of population growth with urban growth areas.