Scientists chart peak orange

For the past three decades, scientists in the US have determined the onset of peak foliage colouration for central and eastern US forests. The results revealed mixed trends for when leaves turned orange, and could improve predictions for carbon dynamics in climate models.

Vegetation cycles play a big role in the world’s carbon fluxes: green leaves absorb carbon dioxide to produce carbohydrates for plant growth, whilst browning leaves mark the end of this process. The later the onset of colouration, and the longer the growing season, the greater the expected carbon uptake – and the less carbon left in the atmosphere. While a lot of studies have focused on the timing of new growth in spring, say Lingling Liu and Xiaoyang Zhang of South Dakota State University, US, fewer have focused on when leaves turn orange.

“Determining the long-term peak-colouration timing and its complexity greatly improves the calculation of the vegetation growing season length, which [in turn] facilitates more reliable measures of carbon dynamics in vegetation–climate interactions models,” said Liu. […]

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