Evaluation of the OSM environments approach yields results which are basically comparable to those obtained with observed communities. Accepted and synthetic plausible candidate observations mostly have higher index values with their OSM environments, than have rejected or synthetic implausible observations. However, the difference between distributions of similarity values of plausible and im- plausible observations is smaller, because especially the sets of synthetic implausible observations have overall higher similarity values than with the former approach. Figure 4.2.1 shows the distribu- tions of Simpson and Jaccard similarity index values for ArtenFinder data resulting from evaluation. AF_SI2 and AF_SI3 are closer to the other distributions, than they were with the observed communi- ties approach. Statistical tests with the Mann-Whitney-U-Test showed, however, that they are still statistically different from AF_A and AF_SP (see Table 4.2.1 and Table 4.2.2).
a) ArtenFinder, Simpson index b) ArtenFinder, Jaccard index
Figure 4.2.1: ArtenFinder, distributions of Simpson and Jaccard similarity index values, OSM envi- ronments approach. n(AF_A) = 15,329; n(AF_SP) = 1,568; n(AF_R) = 215; n(AF_SI1 = 2,104; n(AF_SI2) = 14,964; n(AF_SI3) = 15,618.
Table 4.2.1: ArtenFinder, results (p-Values) of Fligner-Killeen-Tests and of Mann-Whitney-U-Tests with AF_A, AF_SP and the four different sets of rejected or synthetic implausible candidate observa- tions, Simpson index, OSM environments approach.
Simpson Index, AF_A vs. AF_R AF_SI1 AF_SI2 AF_SI3
Fligner-Killeen-Test 0.8047 < 2.2*10-16 < 2.2*10-16 < 2.2*10-16 Mann-Whitney-U-Test 9.577*10-9 < 2.2*10-16 < 2.2*10-16 < 2.2*10-16
Simpson Index, AF_SP vs. AF_R AF_SI1 AF_SI2 AF_SI3
Fligner-Killeen-Test < 2.2*10-16 < 2.2*10-16 < 2.2*10-16 < 2.2*10-16 Mann-Whitney-U-Test < 2.2*10-16 < 2.2*10-16 < 2.2*10-16 < 2.2*10-16 Table 4.2.2: ArtenFinder, results (p-Values) of Fligner-Killeen-Tests and of Mann-Whitney-U-Tests with AF_A, AF_SP and the four different sets of rejected or synthetic implausible candidate observa- tions, Jaccard index, OSM environments approach.
Jaccard Index, AF_A vs. AF_R AF_SI1 AF_SI2 AF_SI3
Fligner-Killeen-Test 0.05772 < 2.2*10-16 < 2.2*10-16 < 2.2*10-16 Mann-Whitney-U-Test 9.886*10-11 < 2.2*10-16 < 2.2*10-16 < 2.2*10-16
Jaccard Index, AF_SP vs. AF_R AF_SI1 AF_SI2 AF_SI3
Fligner-Killeen-Test 2.505*10-5 < 2.2*10-16 < 2.2*10-16 < 2.2*10-16 Mann-Whitney-U-Test < 2.2*10-16 < 2.2*10-16 < 2.2*10-16 < 2.2*10-16
Properties of OSM Environments
ArtenFinder observations up to 2015 are of 2,957 different species. Of these, 1061 species have 10 or more accepted observations. Extracting the OSM tags which surround these observations, reducing them to frequently associated tags and filtering out the nonspecific tags produces 415 OSM environ- ments with 10 or more tags. There are 25 nonspecific tags which are associated to 50% or more of the target species (see Table 5.2.6, in the discussion chapter). 39 nonspecific species (resulting from the observed communities sensitivity analysis with analogous parameter settings, see section 4.3.1) were not used for evaluation purposes. 26 of these species have OSM environments with less than 10 tags anyway, so that 402 valid OSM environments remain for use in evaluation. Sizes of these OSM envi- ronments range from 10 to 105 tags (mean: 19.5). See Table 4.2.3 for an overview of these numbers for ArtenFinder data. Using a much lower number of min. 10 target species for OSM environment extraction (vs. min. 100 observations necessary for observed communities extraction in the evaluation of that approach) led to a higher number of valid OSM environments when compared to the number of valid observed communities. Valid OSM environments belong to 18 species groups. Most belong to plants (37.8%), followed by birds (16.7%) and the group of butterflies and moths (14.9%).
Table 4.2.3: ArtenFinder, key numbers describing valid OSM environments. No. of valid OSM envi-
ronments
Mean no. of tags in OSM environments No. of nonspecific tags No. of nonspecific species 402 19.5 25 39
Properties of Sets of Valid Candidate Observations
Table 4.2.4 lists some key parameters describing the sets of valid candidate observations resulting from evaluation with ArtenFinder and OSM data. Sets of valid candidates are different in size. Mean numbers of tags in candidate contexts and mean numbers of tags in OSM environments associated to these cases also differ between sets. AF_SI3 deviates strongly in mean size of its candidate contexts, and in mean no. of tags (incl. nonspecific tags) around candidates, which are both much lower due to the method of creation of this set (see section 3.3.2). Compared to AF_A, AF_R has smaller and
AF_SP larger OSM environments associated to its candidates. Numbers of valid candidate cases are lower in all sets, than they were in observed communities approach evaluation. This is the case alt- hough the number of valid OSM environments (and thus the number of evaluated target species) is higher (see above). However, less candidate cases were evaluated as valid because many are situated in locations with too few tags (< 10) within the relevant neighborhood.
Table 4.2.4: ArtenFinder, key numbers describing sets of valid candidate observations, OSM environ- ments approach.
Set of candidates
No. of valid can- didate cases
Mean no. of tags in
candidate contexts
Mean no. of tags in OSM environ- ments, per set of
candidates
Mean no. of con- text tags (incl. nonspecific tags) AF_A 15,329 35.6 19.1 56.3 AF_SP 1,568 39.8 31.6 61.9 AF_R 215 32.8 16.2 52.9 AF_SI1 2,104 33.2 19.8 53.6 AF_SI2 14,964 34.0 19.1 54.3 AF_SI3 15,618 23.2 19.1 41.0
Table 4.2.5: ArtenFinder, portions of species groups in sets of candidate observations used in evalua- tion, OSM environments approach.
AF_A AF_SP AF_R AF_SI1 AF_SI2 AF_SI3
Species group (%) (%) (%) (%) (%) (%) plants 5.7 1.1 2.4 0.0 5.6 6.0 fungi 1.4 0.6 0.0 0.0 1.3 1.4 mammals 1.9 2.0 0.5 0.0 1.9 2.0 birds 65.9 78.9 12.1 90.4 66.3 65.3 reptiles 3.3 1.0 2.8 3.9 3.3 3.3 amphibians 0.4 0.2 0.9 0.0 0.4 0.4 butterflies and moths 6.6 6.0 28.8 1.3 6.5 6.7 hymenopterans 1.8 0.8 2.3 0.0 1.7 1.8 beetles 0.7 0.4 0.9 0.0 0.7 0.7 dragonflies and damselflies 9.7 8.1 43.3 0.7 9.6 9.8 mantids 0.4 0.1 0.0 0.0 0.4 0.4 locusts 1.2 0.3 3.7 0.0 1.2 1.1 crustaceans 0.0 0.0 0.0 0.0 0.0 0.1 mollusks 0.5 0.1 0.5 3.8 0.5 0.5 true bugs 0.4 0.4 0.0 0.0 0.4 0.4 neuropterans 0.0 0.0 1.9 0.0 0.0 0.0
Species group compositions of the sets of valid candidate observations are shown in Table 4.2.5. Spe- cies group compositions of AF_SI2 and AF_SI3 are, expectedly, almost identical to AF_A, (AF_SI2 and AF_SI3 were created based on AF_A observations, see section 3.3.2). AF_SI1 and AF_SP have higher portions of birds. These findings go along with effects found also in observed communities approach evaluation. However, dominance of bird observations in most sets is now much stronger than in observed communities approach evaluation. The slightly higher portion of plants in candidates is an effect introduced by using a lower threshold of 10 or more (instead of 100 or more) observations of a target species available in approved observations up to 2015 for OSM environment generation. This also causes the number of species groups to be higher than in observed communities approach evalua- tion (16 vs. 13).
a) AF_A (n = 15,329) b) AF_SP (n = 1,568)
Figure 4.2.2: Spatial distribution of valid candidate observations in sets of accepted and synthetic plausible ArtenFinder candidates, OSM environments approach. (No. of points in 10x10 km raster. Classified by Natural Breaks. Source of Rheinland-Pfalz state line: LANIS Rheinland-Pfalz.)
In the sets AF_A, AF_R and AF_SI1, the general northwest to southeast trend of growing observation density was not changed by the selection of valid candidate observations in evaluation, because these depend strongly on the overall distribution of ArtenFinder observation density in Rheinland-Pfalz, see Figure 4.2.2 and Figure 4.2.3. This is also true for the set AF_SP, which is based on synthetic, spatial- ly random observations. AF_SP observations are located close to plausible AF_A observations which have their highest densities in southeastern Rheinland-Pfalz. However, the sets AF_SI2 and AF_SI3, which are also based on synthetic random points, almost invert the northwest to southeast trend of observation density, because they represent observations away from known occurrences of the species they represent. Even AF_SI2, which has synthetic observations in situations with similar OSM tag density as AF_A observations, shows this effect, because OSM tag density does not have a northwest to southeast trend. This finding confirms that OSM data in Rheinland-Pfalz are indeed capable of providing sufficient numbers of context tags for plausibility estimation in regions where observation density is insufficient for this purpose. With the observed communities approach, the northern and northwestern parts of Rheinland-Pfalz were practically devoid of valid candidate observations. This was not only the case for real observations (scarce in these regions anyway), but also for synthetic candidate observations based on random points, which did not find adequate context observation den- sities to provide valid numbers of context species in these regions.
a) AF_R (n = 215) b) AF_SI1 (n = 2,104)
c) AF_SI2 (n = 14,964) d) AF_SI3 (n = 15,618)
Figure 4.2.3: Spatial distribution of valid candidate observations in sets of rejected and synthetic im- plausible ArtenFinder candidates, OSM environments approach. (No. of points in 10x10 km raster. Classified by Natural Breaks. Source of Rheinland-Pfalz state line: LANIS Rheinland-Pfalz.)