Extreme heat and drought severely damage woods and forests. But how to understand when the limit beyond which trees and plants die is exceeded? To answer this question, the first is born global database which records forest death events precisely geo-referenced in 675 locations, from 1970 to today. To develop it, an international group of scientists including the Madrid Polytechnic and theUniversity of Florida. The work, which covers all forested continents, compares that information with existing climate data to determine the hot, dry climatic conditions that caused these documented episodes of tree mortality. The data can determine how much heat associated with drought is ‘too much’ for forests. The study is published in the scientific journal Nature Communications.
“In this study, we’re letting the forests of the Earth do the talking,” he says William Hammond, a plant ecophysiologist at the University of Florida, who is leading the study. “We collected data from previous studies documenting where and when the trees died. Then, we looked at what the weather was like during mortality events, compared to long-term conditions. ” After performing the climatic analysis of the years related to the observed forest mortality events, the authors note, a pattern was evident.
“What we discovered – Hammond describes – is that, on a global scale, there is a consistently hotter and drier pattern, what we call an unmistakable drought level footprint coupled with the heat that puts forests at risk of death ”. The ‘unmistakable footprint’ shows that the vegetation mortality it has occurred consistently when the typically hottest months of the year have had extremely hot and dry seasons. “Our unmistakable footprint revealed that global forest mortality correlates with escalating climatic extremes,” the authors point out.
Using data from the climate model, we estimate how often these deadly weather conditions will occur in a scenario of further warming, compared to the pre-industrial climate: from 22% more frequent if there is an increase of 2 ° C, up to 140% more frequent if the increase is 4 ºC “. This rise in temperatures would more than double the frequency with which forests around the world experience tree-killing droughts, he adds. “We hope this document creates some urgency on the need to understand the role of warming in forest mortality,” the authors note. “Furthermore, we hope that our open access database will allow for further study,” the authors point out.