A thirteen‐year study on the impact of a severe canker disease of Corymbia calophylla, a keystone tree in Mediterranean‐type forests

Abstract

Worldwide, forests and woodlands have shown progressive declines in health as a result of global environmental changes in combination with local anthropogenic drivers. This study examined the incidence and progression of a canker disease of marri (Corymbia calophylla) caused by the endemic fungal pathogen Quambalaria coyrecup at three paired forest and anthropogenically disturbed sites in the southwest of Western Australia over 13 years. At the time of plot establishment in 2001, cankers were present on trees at all six sites with 22.7% of the assessed trees cankered. By 2014, cankers had led to the death of 6.7% of the trees, and an additional 10.0% of the trees developed cankers during this time. A further 2.3% of trees died due to causes other than canker, resulting in a final figure of 65.0% of trees remaining alive and free of cankers for the duration of the survey period. Canker incidence was significantly greater on trees present at anthropogenically disturbed sites (along roadsides and in paddocks) than forest trees (35.3%increasing to 50.7%, 10.0% increasing to 14.7%, respectively). Trunk diameter at breast height, tree height and crown ratings were not correlated with canker presence. This long-term study provides evidence of the increasing severity of this canker pathogen and the impact it is having on the survival of marri.

Field survey, isolation, identification and pathogenicity of Phytophthora species associated with a Mediterranean‐type tree species

“…The disease would enter C. calophylla bark by means of an opening or injury (Shearer, 1994;Smith, 1970), where it would develop into a canker, often girdling the tree. Disease development is slow, especially in the bigger branches-C. calophylla's ability to exude kino probably slows down disease progress-but the final stages of this disease always lead to the death of the infected tree (Paap et al, 2016;Smith, 1970). The disease affects trees irrespective of height of the tree, diameter at breast height (DBH) or crown condition (Paap et al, 2016).…”

“…Disease development is slow, especially in the bigger branches-C. calophylla's ability to exude kino probably slows down disease progress-but the final stages of this disease always lead to the death of the infected tree (Paap et al, 2016;Smith, 1970). The disease affects trees irrespective of height of the tree, diameter at breast height (DBH) or crown condition (Paap et al, 2016). The cause of this disease remained unknown (Shearer, 1992), until Paap, Burgess, McComb, Shearer, and Hardy (2008) identified an endemic pathogen, Quambalaria coyrecup as the causal agent.…”

Anthropogenic Disturbance Impacts Mycorrhizal Communities and Abiotic Soil Properties: Implications for an Endemic Forest Disease

“…Low ECM fungal diversity was associated with disturbed, diseased edges in comparison to undisturbed areas. ECM fungi are important for tree health as they provide nutrients for their host and produce a mantle around root tips which is thought to provide protection against root pathogens (Albornoz et al, 2017); however, Q. coyrecup most likely spreads aerially, but epidemiology of this pathogen in relatively unknown (Paap et al, 2016). Therefore, communities of ECM fungi are not directly protecting against Q. coyrecup.…”

What feeds onQuercus ilexL.? A biogeographical approach to studying trophic interactions in a Mediterranean keystone species

“…Large isolated trees belonging to these species can ameliorate harsh climatic conditions (Joffre et al, 1999) and increase soil nutrient levels (Joffre & Rambal, 1993;Munzbergova & Ward, 2002), plant species richness (Guevara et al, 1992) and structural complexity, as well as provide habitats for animals (Manning et al, 2006). Other trees that are considered keystone species include Quercus douglasii, Sclerocarya birrea, Quercus griffithii, Schinziophyton rautanenii, Corymbia calophylla and Populus tremula (Chidumayo, 2016;Helm & Witkowski, 2012;Kivinen et al, 2020;Paap et al, 2017;Rice et al, 1993;Singh et al, 2015).…”