Soil microorganisms in montado: a strategy for adaptation to climate change

Abstract

The Montado is a particularly resilient Mediterranean forest ecosystems, rich in biodiversity and of great importance for nature conservation, However, it is exposed to threats from environmental pressures aggravated by global climate change and human pressure, which is leading to its decline. Soil microorganisms are crucial in the maintenance of several soil functions including the regulation of soil nitrogen available to plants. The bacteria in the root nodules of legumes (known as rhizobia) can improve the performance of these agroforestry ecosystems due to the process of biological nitrogen fixation that is carried out by the symbiosis established between these bacteria and legumes. In Portugal, the widespread mortality recorded in cork and holm oaks in recent decades is due, among other factors, to infections by Phytophthora spp. in the roots of these trees. It is therefore important to develop means of biocontrol for this disease. The present work is based on the evaluation of the size and effectiveness of the rhizobial population existing in Montado soils. It was also evaluated, the in vitro antagonist activity to Phytophthora, of the bacteria isolated from root nodules, phosphate solubilization and the ability to degrade cellulose, an essential component of Phytophthora cell wall.