Figure 1.
Outline of statistical approaches.
Flow chart summarizing the sequence of statistical methods used in this study. Step 1 comprised the time series modeling, based on RDA where time was modeled with a PCNM approach, to determine the independent temporal trends of species groups of invertebrate communities in the lakes. Steps 2 and 3 describe the preparation of environmental and spatial matrices, which were then used in the variance partitioning (step 4). For further details see methods.
Figure 2.
Modeled temporal species group patterns.
Temporal patterns of species group 1 associated with RDA axis 1, and species group 2 associated with RDA axis 2 (lc, linear combination, scores) for benthic invertebrates between 1988 and 2007. Shown are the overall patterns (means ± SE) from 26 lakes with significant temporal structure. Both species groups have been identified and separated by the time series modeling analysis based on different temporal structure of the taxa that comprise a community.
Table 1.
Spearman rank correlations between water quality variables and species group patterns, revealed by time series modeling, for invertebrate communities between 1988 and 2007.
Figure 3.
Spatial patterns of temporal patterns.
Result from spatial analysis showing broad-scale spatial structure of invertebrates in the time-explicit metacommunity analysis. The size of the symbols are proportional to the lower-order PCNM vectors that describe this spatial structure and the color represents the sign (white = negative, black = positive). Numbers within squares refer to lake identity: 1, Abiskojaure; 2, Allgjuttern, 3, Brunnsjön; 4, Brännträsket; 5, Bysjön; 6, Fiolen; 7, Fräcksjön; 8, Grissjön; 9, Hagasjön; 10, Harasjön; 11, Humsjön; 12, Härsvatten; 13, Jutsajaure; 14, Mäsen; 15, Remmarsjön; 16, Rotehogstjärnen; 17, Skärgölen; 18, Stora Skärsjön; 19, Stensjön; 20, Storasjö; 21, Stora Envättern; 22, Stor-Tjulträsket; 23, Sännen; 24, Tväringen; 25, Älgarydssjön; 26, Övre Skärsjön.
Figure 4.
Dispersal characteristics (A, female dispersal; B, adult dispersal) of taxa contributing to the temporal dynamics of species groups 1 and 2, respectively. Shown are the mean percentages ± standard deviations of species showing the traits across the study lakes.
Table 2.
Results from variance partitioning analyses.