Research press release


Nature Geoscience

Size matters for Amazonian trees during dry spells



Pierre Gentineたちは、アマゾンの森林において背の高い木と低い木の光合成が、干ばつに対してどの程度影響を受けやすいかを分析した。その結果、30メートルを越す高い木は、20メートル以下の木よりも干ばつに対して3倍影響を受けにくいことが明らかになった。背の高い木はより広範囲に根を張るため、乾期の間も深部の湿潤な土壌に到達することができる。しかし、背の高い木は大気の乾燥にはより影響を受けやすい。背の高い木の葉は、常に水分の含有量が低いため、光合成は土壌の干ばつには適応しやすいが、大気中の水分の変動には影響を受けやすくなる。


Taller trees in tropical forests are more resilient to drought, reports a paper published online this week in Nature Geoscience.

Severe droughts in the Amazon jungle - a potential consequence of global climate change - could lead to widespread forest losses. It is not known, however, what role different tree attributes, such as height, play in the response of forests to drought.

Pierre Gentine and colleagues analysed how sensitive the photosynthesis of tall and short trees in Amazon forests is to drought. They find that tall trees above 30 metres are three times less sensitive to drought than short trees under 20 metres. Taller trees have more extensive root systems that allow them to reach deep soil moisture during dry seasons. They are, however, more vulnerable to atmospheric aridity. Leaves on tall trees constantly have a lower water content, which makes their photosynthesis more adaptable to soil drought but also more sensitive to fluctuations in atmospheric water.

The authors conclude that forest height may play as important a role as precipitation levels in regulating photosynthesis to cope with climate variations.

doi: 10.1038/s41561-018-0133-5


メールマガジンリストの「Nature 関連誌今週のハイライト」にチェックをいれていただきますと、毎週各ジャーナルからの最新の「注目のハイライト」をまとめて皆様にお届けいたします。