Look for complete geospatial metadata in this layer's associated xml document available from the download link * Metric Name: Distribution of Redwood Structure Classes * Tier: 2 * Data Vintage: 2012 * Unit Of Measure: Thematic * Metric Definition and Relevance: Coast Redwoods grow in a band from the coast of central California to southern Oregon. Compared to forests of the past, today’s redwood forests are fragmented, smaller, and more stressed than ever throughout their range. Logging and clearcutting that began over a century ago destroyed redwood forests on an industrial scale for many decades. Forest regeneration after clearcutting created unnaturally dense forests with high competition among trees for light and water, reduced genetic diversity, and impaired ability to store carbon or provide ample habitat for native species. The remaining old-growth forests are fragmented by these logged forests and threatened by residential development, roads, changes in climate, and the lack of productive, natural fires. The current extent of old-growth forest in the coast redwood ecosystem is only 5 percent of the original 2.2-million acre forest (~113,000 acres) and is, therefore, of significant concern. The vast majority of remaining old-growth (89,000 acres) is in Humboldt and Del Norte counties. The first-ever State of Redwoods Conservation Report provides a contemporary look at the state of coast redwood and giant sequoia forest health in California. Its purpose is to serve as a reference guide to their status today and discuss the key variables that matter most to their future health: overall age and condition of the forests, varied ownership and protection of redwood and giant sequoia forests, key stressors, and environmental challenges. As governments, nonprofits, landowners, and community partners work to repair the damage done over the last centuries, this report will help all of us in the critical work of protecting what we have, rehabilitating what is damaged, and identifying critical areas and opportunities for future protection and restoration. * Creation Method: The project area was defined as any Hydrologic Unit Code (HUC) 12 watershed, the smallest hydrological units comprehensively mapped by the U.S. Geological Survey, within 1.6 km (1 mile) of known existing natural redwoods (CALVEG 2004; Save the Redwoods League, unpublished data). When clipped to this region the Landscape Ecology, Modeling, Mapping and Analysis Gradient Nearest Neighbor (LEMMA GNN) structure map (hereafter LEMMA) contained 3,867 pixel classes, with each pixel corresponding to a 30 m x 30 m LANDSAT pixel (Ohmann and Gregory 2002). These pixel classes were classified into 24 species and structure classes. Forest species was biased toward redwood by first categorizing any pixel with > 10 percent of basal area of redwood as redwood, likewise any remaining pixels with > 70 percent basal area of Douglas-fir ( _Pseudotsuga menziesii_ (Mirb.) Franco), > 50 percent basal area of tanoak ( _Notholithocarpus densiflorus_ (Hook. & Arn.) P.S. Manos, C.H. Cannon, & S.H. Oh) were classified as those species, and the remaining pixels were classified as mixed conifer-hardwood. Structure classes were based on four classes in Spies and Franklin (1991): 1) Canopy Closure, 2) Biomass Accumulation, 3) Maturation and 4) Large Complex Forest (LCF). The Biomass Accumulation stage was further subdivided into three classes (early, middle, late). The LCF class includes areas of old-growth, but the term LCF is used because some areas with structural complexity similar to old growth forest may actually consist of largely second growth trees. This distinction is important, in part, because remote sensing is unreliable at determining forest age. Pixels were classified into these six classes using trees per acre (TPA) and dominant quadratic mean diameter (QMD) as modeled by LEMMA. The classes were defined as: 1) Canopy Closure: 50 percent of stems < 20.3 cm (8 inches) 2a) Early biomass accumulation (BA): QMD < 40.6 cm (16 inches) or 300 TPA and QMD < 81.3 cm (32 inches) 2b) Mid BA: QMD < 61 cm (24 inches) or 200 TPA and QMD < 81.3 cm (32 inches) 2c) Late BA: QMD < 81.3 cm (32 inches); 3) Maturation: 50 percent of stems < 122 cm (48 inches) 4) LCF: <50 percent of stems <122 cm (48 inches). The Save the Redwoods League then used its old-growth database, which includes polygons of old growth throughout the range, to further refine the LCF class. The old growth database was developed in 2009 through a combination of field data and review of aerial images. To ensure that these areas were appropriately captured as LCF, LEMMA pixel types (based on the Forest Inventory and Analysis plots that were used in the LEMMA GNN model) that are only found inside an old-growth polygon were converted to LCF throughout the range. * Credits: State of Redwoods Conservation Report:[ **** https://www.savetheredwoods.org/about-us/publications/state-of-redwoods- conservation-report-2018/](https://www.savetheredwoods.org/about- us/publications/state-of-redwoods-conservation-report-2018/)