Stem mapping methodologies and analyses of stem density, plot size, sample size and spatial patterns of large trees in old-growth mixed-conifer and pine forests of the Sierra Nevada and Oregon

Large trees (>76.2 cm d.b.h.) at seven study sites (16—100 ha) were mapped using a GPS/laser rangefinder/digital compass system that has a measurable, sub-meter, error for any given point. Tree locations mapped with a tape and compass methodology were almost indistinguishable from the GPS maps at short distances, but required more time. Total survey station maps were compared to the GPS-based system and were more accurate at short distances (<1 m) and in small plots than, but the total survey station is slower and its error in distance and azimuth can compound unpredictably over long distances and multiple set-up points if the survey grid cannot be reasonably closed in difficult forest conditions.; The actual mean large tree density at the study sites had a range of 8.7–27.3 stems/ha. Density of individual species peaked at 14.9 stems/ha for ponderosa pine, 11.3 stems/ha for Jeffrey pine, 8.2 stems/ha for incense cedar, 6.3 stems/ha for sugar pine, and 4.5 stems/ha for white fir. Both plot size (1000 m2, 4000 m2, or 10,000 m2 ) and the number of samples used (1–30 samples) were comparatively analyzed. In order to achieve a density estimate within one standard deviation of the mean, at least 17, 9 or 5 separate samples are required for plot sizes of 1000 m2, 4000 m2, or 10,000 m2, respectively. As the plot sizes increase, the mean and are median larger; the interquartile range is narrower; the maximum density is smaller and the minimum—zero—is the same.; Both fine-scaled (<1 ha) and coarse (>10 ha) stem density and spatial patterns were detected at all study sites. Aggregated patch sizes exist at one, three and eight hectares when all species, study sites and size classes are considered together. The mean patch size of the smallest size class (76.2 –99.9 cm d.b.h.) is 1/5th hectare, while the largest size class (>125 cm d.b.h.) had mean patch sizes of fifteen hectares. On average, large Jeffrey pine trees are clumped at one, four and nine hectares; ponderosa pine at 1/2, two, five and ten hectares; sugar pine at one-quarter, one, five and nine hectares; incense cedar at 1/50th, four and twelve hectares; and white fir at one and a half, four and sixteen hectares.*; *This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirement: Microsoft Office.