Empirical prediction models for the coverage and yields of cowberry in Finland

Empirical models for the coverage and berry yield of cowberry (Vaccinium vitis-idaea L.) were developedusinggeneralizedlinearmixedmodels �(GLMMs). �Thepercentagecoverageofcowberry� waspredictedasafunctionofsiteandstandcharacteristicsusingdatafromtheFinnishNational � ForestInventory �(NFI) �in �1995. �Theaverageannualyield, �includingthebetween-yearvariation � intheyield, �waspredictedasafunctionofpercentagecoverageandstandcharacteristicsusing � permanentexperimentalplots �(MASI) �establishedindif ferentareasofFinlandandmeasuredin � 2001-2012.�Themodelforcowberryyields �(Model �2) �wasdevelopedformineralsoilforests. � Themodelforthecoverage �(Model �1) �wasconstructedsothatitconsidersbothmineralsoil � sitesandalsomanyothersiteswherecowberryoccursinthefieldlayer . �AccordingtoModel �1, � thesitefertilitysignificantlyaf fectedtheabundanceofcowberryonmineralsoils, �sprucemires � and pine mires. The stand basal area and dominant tree species were among the most important foreststructuralpredictorsinModel �1. �Thesitefertilitywasnotasignificantpredictorinthe � cowberryyieldmodel. �Instead, �thestandbasalareaandcoverageofcowberryplantswerefound � tobestatisticallysignificantpredictorsinModel �2. �Theestimat edmodelswereusedtopredict � thecowberrycoverage, �averageannualyieldandits �95% �confidenceintervalalongwithstand � development.�Themodelsofthisstudycanbeusedformulti-obj ectiveforestplanningpurposes.