An early spring means trees use up crucial soil nitrogen too early

Apparently forests use up the nitrogen in soil faster during the typically earlier, greener springs we’re getting thanks to climate change. And it’s affecting trees in unusual ways.

The University of Maryland Center for Environmental Science has found that our fast-warming climate is causing earlier springs and later autumns in the USA’s vast eastern forests. This in turn makes the growing season longer, and changes the way forests work.

More demand for nitrogen means trees run out of food before autumn

It looks like earlier springs increase the trees’ demand for nitrogen, which means fewer leaves later in the growing season as well as early, pre-fall leaf loss. Trees use up more nitrogen in these early springs than the soil contains naturally, which in turn affects the amount of CO2 they’re able to remove from the air.

The positive side – Might this mean cleaner water?

The researchers harnessed a blend of satellite images and field measurements to reveal trees’ extra demand for soil nitrogen during early springs. The good news is that a bigger demand for nitrogen might mean less nitrogen finding its way into lakes, rivers and streams. The trouble is, earlier springs mean there isn’t enough nitrogen in the soil to ‘feed’ the trees throughout the elongated growing season.

Affecting forest growth rates

The scientists studied 222 trees, broken into three species, in Prince William Forest Park, Harpers Ferry Historical Park, Catoctin Mountain Park and Great Smoky Mountains Park, studying three decades of satellite imagery and comparing it with wood production and wood chemistry data.

While forest growth rates aren’t slowing down quite yet, they are not as good as they might be if there was enough nitrogen in the soil to last the full season

Article on behalf of The Rainforest Foundation.


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