Variation in vegetation cover between shrubland, woodland and forest biomes invaded by Phytophthora cinnamomi

Abstract

Pathogen mediated changes in vegetation cover were determined from variation of ground cover and canopy closure between diseased and adjoining healthy areas of Banksia shrubland, Banksia woodland and Eucalyptus marginata forest biomes invaded by Phytophthora cinnamomi. For healthy areas, ground cover tended to be greatest in the relatively low rainfall areas where canopy closure was the least. Ground cover significantly decreased, but canopy closure significantly increased with plant height in healthy areas. Disease caused by P. cinnamomi resulted in a mean decrease in ground cover of ~28% for infested woodland and forest biomes. This decrease was significantly greater than the mean decrease in ground cover of 14% for shrubland biomes. In contrast disease decreased mean canopy closure in shrubland biomes by 32% which was significantly greater than the decrease of ~22% for diseased woodland and forest biomes. Re-establishment of vegetation cover using resistant selections of local dominant plant species may substantially return to infested areas the functionality of healthy areas.