Evaluation of a visual assessment method for tree condition of eucalypt floodplain forests

Abstract

Summary For decades the floodplain forests of the River Murray have endured the effects of prolonged water stress. This has resulted in significant crown dieback and loss of condition. The Living Murray (TLM) initiative aims to restore the ecological health of six Icon Sites along the River. The two eucalypts River Red Gum (Eucalyptus camaldulensis) and Black Box (Eucalyptus largiflorens) that dominate the forests at five of the six Icon Sites are undergoing widespread decline. To enable effective management and restoration of these forests, we developed a standardised tree condition assessment method. Named the TLM tree condition assessment method, it utilises visual assessment of a range of tree crown variables (extent and density of the foliage in the crown, epicormic growth, new tip growth, reproductive activity, leaf die‐off, mistletoe infestation) and measurements of bark condition, diameter at breast height and dominance class. This article describes the TLM tree condition assessment method and assesses it for consistency between multiple observer teams after limited training. The level of observer agreement between six teams each comprised of two observers was assessed for seven of the ten variables. Intra‐class correlation was used to compare scores of 30 River Red Gum trees assessed on Gunbower Island on the River Murray. The level of agreement for all variables was statistically significant with six of seven variables having correlation coefficients over R = 0.5. The TLM tree condition assessment method was found to provide accurate estimates of a range of tree variables that can be used to determine tree condition. The TLM tree condition assessment method provides a valuable monitoring tool that can be used to assess management interventions, such as management flooding and silvicultural thinning.