Global team of scientists determine ‘fingerprint’ for how much heat, drought is too much for forests

Scientists to map volcanic eruption’s impact on Tonga seabed

NIWA’s research vessel, RV Tangaroa, will head over on April 9 to collect video images of the seafloor and another vessel, from British enterprise SEA-KIT International, will conduct further mapping over a month.

Project leader and NIWA chief scientist of oceans Mike Williams predicts they will see massive changes to the underwater landscape around Tonga.

Williams said the lack of knowledge about these types of volcanoes, particularly along the Pacific Ring of Fire, was a risk to society.

“Before the eruption, much of the volcano was above water but now none of it is and the neighbouring islands of Hunga-Tonga and Hunga-Ha’apai were reduced in size. We expect similarly dramatic changes to have occurred in the underwater topography.

“Submarine cable breakages show impacts up to 50 kilometres from the volcano caldera, implying changes to the seabed over an area of at least 8000 square kilometres.”

Echosounders – a device which determines the depth of the seabed and detects objects in water – will be used to inform scientists about the thickness of ash deposits and the formation of any new bedforms…READ ON

Global team of scientists determine ‘fingerprint’ for how much heat, drought is too much for forests

How hot is too hot, and how dry is too dry, for the Earth’s forests? A new study from an international team of researchers found the answers—by looking at decades of dying trees.

Taken in 1993, this photo shows the mortality of historical forests of Atlas Cedar in Morocco. Credit: Csaba Mátyás, professor emeritus, University of Sopron, Hungary

Just published in the journal Nature Communications, the study compiles the first global database of precisely georeferenced forest die-off events, at 675 locations dating back to 1970. The study, which encompasses all forested continents, then compares that information to existing climate data to determine the heat and drought climatic conditions that caused these documented tree mortality episodes.

“In this study, we’re letting the Earth’s forests do the talking,” said William Hammond, a University of Florida plant ecophysiologist who led the study. “We collected data from previous studies documenting where and when trees died, and then analyzed what the climate was during mortality events, compared to long-term conditions.”

After performing the climate analysis on the observed forest mortality data, Hammond noted, a pattern emerged…READ ON

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