Arboriculture & Urban Forestry 42(1): January 2016 63 than all other land uses in the F1 profiles. In the F2 profiles, OU had lower richness than FR. In the F3 profiles, ST had lower richness than OM and FR. The ANOSIM global R values were all significant (P ≤ 0.014), but low (F1= 0.371, F2 = 0.200, and F3 = 0.187). The F1 fungal community profiles showed the NM sites were well separated from the OM and FR sites, and overlapped with the OU and ST pro- files (Table 3). The separations between NM and the other land uses were the product of highly similar fungal communities within the NM sites (Figure 2). All other comparisons were not significant. Figure 1. The 2-D MDS plot created from the edaphic vari- ables measured from soils collected on 17 and 18 May 2009 from: street side terraces (), new managed (), old man- aged (Δ), old unmanaged (), and forest () properties in metropolitan Milwaukee, Wisconsin, U.S. Each sample prop- erty is represented by its land use. The dashed outlines indi- cate groupings created from a Euclidian distance cluster diagram (distance 4). Analysis of Bacterial Communities The intensity of urbanization had little effect on biodiversity within the bacterial community. Eight of the twelve biodiversity comparisons were insig- nificant (data not shown); however, FR had higher average richness and Shannon diversity than OU. Differences in the bacterial community profiles among the land uses were detected with ANOSIM and MDS. The global R values were all significant (P = 0.001) but generally low for all three bacterial profiles, ranging from 0.269 (B3) and 0.461 (B1). Pairwise comparisons within the B1 and B2 profiles indicated bacterial communities in FR, OM, and NM are well separated from one another (R > 0.70) (Table 3). However, the distinctive clusters represented by the NM, OM, and FR profiles were grouped in close proximity to one another, suggesting large-scale sim- ilarities exist among these communities (Figure 2). Analysis of Fungal Communities No consistent land-use effects on fungal diversity indices were observed among all three fungal pro- files. However, increased urbanization appeared to decrease richness. There were also significant differ- ences in the diversity of seven of the twelve fungal land-use comparisons (data not shown). Specifi- cally, ST had lower average fungal richness, even- ness, Shannon diversity, and Simpson diversity PLFA/FAME Estimates of Microbial Biomass and Community Analysis Three of the four biodiversity indices revealed sig- nificant differences among land uses (data not shown) with ST resulting in lower evenness, Shan- non diversity, and Simpson diversity than FR and OM. However, total microbial biomass did not dif- fer significantly (P = 0.579) among the land uses. The global R value (0.359) was significant (P = 0.001) but low (Table 3). Post hoc analysis indicated a high degree of variability within and between the land uses, resulting in land-use community profiles that were not well separated (R ≤ 0.680). The MDS (Figure 3) was consistent with the ANOSIM results. Litterbag Decomposition Analysis The biological decomposition of the transposed leaf litter was consistent in all land uses. Over time, the C:N ratio of transposed leaf litter declined signifi- cantly (P = 0.001) in all land uses, with an average C:N ratio across all sites following 0-, 10-, 30-, 60-, 90-, and 120-day incubation of 66.80, 52.72, 43.35, 37.51, 34.67, and 34.49, respectively. The declines in C:N ratio, however, did not differ among land uses in any of the sampling periods, where P = 0.649, 0.521, 0.524, 0.116, and 0.097 for the 10-, 30-, 60-, 90-, and 120-day sampling periods, respectively. DISCUSSION The detected differences in microbial communities among the land uses were not consistent across all TRFLP or lipid community profiles, and tended to be most pronounced in comparisons between the least (forest) and the most (street) urbanized land- scapes. Regardless, even at the extremes of human ©2016 International Society of Arboriculture
January 2016
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