Biodiversity, Conservation & Ecosystems

 At least a tenth of the world’s mature giant sequoia trees were destroyed by a single California wildfire that tore through the southern Sierra Nevada last year.

Fire crews were still putting out embers and hot spots Sunday of a massive blaze at a recycling yard that authorities say drew the largest response in the Phoenix Fire Department’s history.

It began with a lightning strike on a parched mountainside above Oro Valley one year ago Saturday.

Scientists have known last year’s Castle Fire was probably the most destructive for California’s famously fire-resilient sequoias in at least 700 years, but a draft National Park Service report obtained by the Visalia Times-Delta puts a quantitative measurement on that fire’s climate-fueled toll. Between 7,500 and 10,000 monarch sequoias — about 10% to 14% of the world’s mature sequoia population — perished in the fire.

Cactus experts are tracking an unprecedented outbreak of “side blooms” on saguaros across Southern Arizona this year.

Some climate activists advocate large-scale tree-planting campaigns in forests around the world to suck up heat-trapping carbon dioxide and help rein in climate change.

Tucson's ambitious tree planting goal aims to improve the health of residents, wildlife, and the watershed.

Years after a lengthy drought, some southeastern Australia rivers show no signs of recovering.