Figure 1.
Locations of 356 sampling sites in the Lower Athabasca region of northeast Alberta.
Black locations (dots) are EMCLA plots with a single survey (observer), while pink locations (dots) are EMCLA plots with repeated surveys by two field observers.
Figure 2.
Non-parametric estimations of (A) all plant species richness and (B) rare plant species richness for the whole study area and each of 9 ecosites.
Figure 3.
Effect of total survey time on (A) all plant richness and (B) rare plant richness using LOWESS (locally weighted scatter plot smoothing).
Figure 4.
Rarefaction-based species accumulation curves for (A) all species and (B) rare species for the whole study region.
Solid curves were the interpolated rarefaction curve from the reference sample. Dashed curves were the extrapolation. Each dot stands for the observed sample number.
Figure 5.
Percent of sampled species richness along different sampling time limitations: (A) first 20-minute sampling, (B) first 40-minute sampling, and (C) first 60-minute sampling.
Table 1.
Total species and number of rare species surveyed in EMCLA plots using two time intervals (20 minute cut-off and post-20 minutes).
Figure 6.
Observer effects on vascular plant richness using data from 36 EMCLA sites with repeated surveys by two observers: (A) total richness comparison, (B) rare plant richness comparison, (C) total survey time comparison, and (D) total richness vs. pseudoturnover rate.
The solid lines were fitted by linear regression models, while the dashed lines were the 1∶1 diagonal lines that represent no bias in sampling among observers.
Table 2.
Summary of total vascular plant richness and rare species richness (in brackets) using the data from 36 EMCLA sites with repeated surveys by two observers.
Table 3.
A direct comparison between EMCLA time-unlimited survey and ABMI (an existing regional biodiversity monitoring program) 20-minute survey for four one-hectare ABMI plots.