Travelling around Oregon and California we have noticed smoke haze from wildfires and in California we have gone past areas of dead burnt trees, which are likely from the bad 2017 year.

The thought occurs, will these trees grow back?

Such fires happen closer to home in Australia every year too, but it’s part of a natural cycle, and Australians we’ve asked say that after about 5 years the bush has recovered and you wouldn’t know from the look of the vegetation that there had been a fire.

The trees that cover America are different from the gum trees of Australia; in the northwest they are substantially conifers.  In California they are a mix depending on the part of the state.

The general trend, not just in the USA, is winters getting colder and summers getting hotter. Conifers cope well with very cold climates but not very hot climates.

Here follows an article on the subject.

Led by Dr Camille Stevens‐Rumann, an ecologist at Colorado State University, the study involved testing fire-struck areas of forest for signs of regeneration.

The scientists examined 1485 sites in the Rocky Mountains, all of which had been affected by fires between 1985 and 2015.

They looked for seedlings growing in the examined sites, comparing growth with nearby unburned forests to determine how well forests in each area were able to regenerate.

The team found the proportion of sites in which no post-fire tree regrowth had taken place increased from 19 to 32 per cent when comparing earlier years of the analysis to the more recent years.

“Significantly less tree regeneration is occurring after wildfires in the start of the 21st century compared to the end of the 20th century,” the scientists wrote in their paper.

Comparing these findings with information on the region’s changing climate suggested increases in global temperatures were influencing forest regeneration, particularly in the driest regions.

“Dry forests that already occur at the edge of their climatic tolerance are most prone to conversion to non-forests after wildfires,” the scientists wrote.

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