JON CARTWRIGHT

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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Oil-palm plantations in Latin America are mostly replacing cattle pasture and other previously intervened lands rather than forests, a study by scientists in Puerto Rico has found.

The research – which also revealed that most exported oil palm stays within the region – suggests that Latin America is a “major opportunity” for the sustainable palm-oil sector, according to the scientists.

“The oil-palm industry has faced enormous scrutiny because of destructive practices in Asia,” said Paul Furumo of the University of Puerto Rico-Río Piedras. “Our study reveals a different narrative of oil-palm expansion in Latin America, one in which cattle pastures and other previously intervened lands are the most significant source of new plantings instead of forests.” […]

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Rising yields in the US Corn Belt are probably due to the adoption of precision agriculture and disproportionate gains on better soils, a newly developed satellite analysis has shown.

The analysis quantified yield heterogeneity both within and between fields for maize and soybean in the US Midwest. It revealed that heterogeneity in maize yields is rising, with average yield differences between the best and worst soils more than doubling since the turn of the century.

That is both good and bad news, according to David Lobell of Stanford University, US. “It’s good that yields have kept rising, and it’s good that farmers are adopting precision agriculture,” he said. “But there are potential problems with relying on a narrowing base of land for gains, just like in the economy there is a problem of relying on growth only [in the] top income brackets. Generally speaking, broad-based growth is more stable and sustainable.” […]

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Scientists in the US and Taiwan have shown that the occurrence of fires in Indonesia is linked to the location, not the strength, of El Niño weather events.

The study, which examined Pacific El Niños over nearly two decades, revealed that El Niños generating sea-surface temperature anomalies over the eastern Pacific are more likely to result in fires than those generating anomalies over the central Pacific.

“We suggest that projecting the location of El Niño events might be more important than projecting their strength for fire management in southern Borneo,” said Min-Hui Lo of the National Taiwan University in Taipei. […]

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