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.

The density of feral honey bee (Apis mellifera) colonies in South East Australia is greater in undisturbed than in disturbed habitats

“…However, excessive water extraction from the Wimmera River has meant that Outlet Creek and the 'lakes' of Wyperfeld National Park have not received flows since 1980. Without periodic flooding, mature riparian woodland vegetation suffers dieback, and there is no recruitment into the population because flooding is required for seedling establishment (George et al 2005;Souter et al 2010). Without changes to water flow, the number of cavities will decline over time and may cause increased competitive pressure between honey bees and regent parrots.…”

“…Due to extensive water extraction from the Wimmera River system, Lake Albacutya (and Outlet Creek) have not seen flows since 1980. The riparian woodland is therefore in decline because it lacks the periodic flooding required for seed germination and seedling establishment (George et al 2005;Souter et al 2010). We chose the edge of Lake Albacutya as one disturbed site for sampling drones.…”

Assessment of ecosystems: A system for rigorous and rapid mapping of floodplain forest condition for Australia's most important river

“…Stand condition was measured from plant area index (PAI), crown extent (Souter et al, ), and the percentage live basal area (%LBA), which are reliable, objective indicators of condition in stands of the river red gum (Cunningham, Read, Baker, & Mac Nally, ). PAI is the area of leaves and stems per unit ground area and was estimated from hemispherical photographs of the canopy classified using image analysis (MultiSpec Application Version 3.1, Purdue University, Indiana) with Winphot 5.00 (ter Steege, ).…”

Wetlands In a Changing Climate: Science, Policy and Management

“…Fortunately, emerging research suggests that vegetation collapse sometimes can be avoided by hydrologic remediation (Souter et al 2010). Freshwater remediation can reduce salinity and revive freshwater forests stressed by salinity intrusion, if the vegetation is not fatally damaged (Middleton et al 2015;Middleton and Souter 2016).…”