Improving the predictive power of spatial statistical models of stream macroinvertebrates using weighted autocovariance functions

Spatial statistical stream-network models are useful for modelling physicochemical data, but to-date have not been fit to macroinvertebrate data. Spatial stream-network models were fit to three macroinvertebrate indices: percent pollution-tolerant taxa, taxa richness and the number of taxalacking out-ofnetwork movement (in-stream dispersers). We explored patterns of spatial autocorrelation in the indices and found that the 1) relative strength of in-stream and Euclidean spatial autocorrelation varied between indices; 2) spatial models outperformed non-spatial models; and 3) the spatial-weighting scheme used to weight tributaries had a substantial impact on model performance for the in-stream dispersers; with weights based on percent stream slope, used as a surrogate for velocity because of its potential effect on dispersal and habitat heterogeneity, producing more accurate predictions than other spatial-weighting schemes. These results demonstrate the flexibility of the modelling approach and its ability to account for multi-scale patterns and processes within the aquatic and terrestrial landscape. © 2014 Published by Elsevier Ltd. Software availability Name of software: SSN Developer: Jay Ver Hoef and Erin PetersonDr Erin Peterson, CSIRO Division of Computational Informatics, EcoSciences Precinct, PO Box 2583, Brisbane, Qld, Australia, 4001. Ph: þ61 7 3833 5536, Email: [email protected] First year available: 2013 Hardware required: Standard laptop or desktop, with Windows or Linux OS Software Required: R statistical software Availability and Cost: Available for free online at http://cran.r-project. org/web/packages/SSN/index.html Program language: R Size: 5.72 MB Nameofsoftware:STARS(SpatialTools for theAnalysisofRiverSystems) Developer: Erin PetersonDr Erin Peterson, CSIRO Division of Computational Informatics, EcoSciences Precinct, PO Box 2583, Brisbane, Qld, Australia, 4001. den), [email protected] ngus Webb), Peter.Negus@ Ph: þ61 7 3833 5536, Email: [email protected] First year available: 2013 Hardware required: Standard laptop or desktop, with Windows OS Software Required: ESRI ArcGIS version 9.3.1, with ArcInfo License Availability and Cost: Available for free online at http://www.fs.fed. us/rm/boise/AWAE/projects/SpatialStreamNetworks.shtml Program language: Python version 2.5 Size: 135 KB Name of software: FLoWS (Functional Linkage of Waterbasins and Streams) Developer: David M. TheobaldConservation Science Partners, 11 Old Town Square, Suite 270, Fort Collins, CO, USA, 80524 Ph: þ1 1 530 214 8905, Email: [email protected] Erin Peterson, CSIRO Division of Computational Informatics, EcoSciences Precinct, PO Box 2583, Brisbane, Qld, Australia, 4001. Ph: þ61 7 3833 5536, Email: [email protected] First year available: 2006 Hardware required: Standard laptop or desktop, with Windows OS Software Required: ESRI ArcGIS version 9.3.1, with ArcInfo License Availability and Cost: Available for free online at http://www.fs.fed. us/rm/boise/AWAE/projects/SpatialStreamNetworks. shtml Program language: Python version 2.5 Size: 556 kB J.C. Frieden et al. / Environmental Modelling & Software 60 (2014) 320e330 321