Subplot vs 1 .0-hectare Tallies 



20 40 60 8( 



Number of Individuals 



100 



that had died in the last 5 years and large live 

 trees (>40 inches). 



Pilot Study subplots had almost no recent 

 mortality (1 vs. 55) and few large live trees (5 

 vs. 93) compared to numbers tallied on full- 

 hectare plots. More large live trees were found 

 on 25 plots in Oregon and Washington in 1994 

 than were recorded for almost 200 California 

 plots measured in 1992-95. Pilot Study field 

 work was restricted to Douglas-fir habitats in 

 western Oregon and Washington. These for- 

 ests have a high percentage of large-diameter 

 trees not tallied in subplot-only data. The sig- 

 nificance of this work is that larger plots will 

 be needed to characterize true overstory con- 

 ditions in Oregon and Washington forests when 

 operational field work starts in the future. 

 Published results for 1992-95 California for- 

 est health monitoring data show that per area 

 estimates of recently dead trees based on sub- 

 plot-only data were significantly different than 

 estimates made from the full-hectare tallies. 



VEGETATION STRUCTURE 



Vegetation structure indicators provide in- 

 formation on species composition, relative 

 cover amount, and spatial distribution of vas- 

 cular plants in the forest. Vegetation measure- 

 ments help describe plant biodiversity and 

 quantify habitat structure, which in turn in- 



fluences wildlife biodiversity and distribution 

 in forest ecosystems. Vegetation structure 

 indicators provide a natural link to other in- 

 dicators including songbird habitat, crown 

 condition, regeneration, and species diversity. 



Vegetation observations and collections are 

 taken in 10.8-square-foot permanent quadrats; 

 each subplot has three quadrats. Three kinds 

 of information are taken for each quadrat: spe- 

 cies identification, height class in which each 

 species occurs, and plant canopy cover. Data 

 were collected for four strata: stratum 1 is from 

 the ground to 2 feet; stratum 2 is from 2 to 6 

 feet; stratum 3 is from 6 to 16 feet; and stra- 

 tum 4 is from 16 feet to the forest canopy. 

 Botanists worked from the lowest stratum 

 upward and used a calibrated range pole and 

 the quadrat frame to define the sample area. 

 Specimens of unknown plants were collected 

 outside the subplots, dried, pressed, labeled, 

 and submitted to the Oregon State University 

 Herbarium, Corvallis, for identification. 



Some 193 species were identified in 25 

 Pilot Study plots. Eleven species were found 

 at 9 or more of the 25 sample sites (table 5-6). 

 As expected, ground and understory layers 

 (strata 1 and 2) had the most species and high- 

 est number of observations per species. Stra- 

 tum 4 had the greatest total cover and the 

 fewest species. 



Botanists collect vegetation structure information 

 in subplot quadrats. 



Monitoring — 74 



