21% more wood, 11% more leavesWhen we hear about calcium, it usually has to do with our bones and teeth and pregnancy... But trees also need the soft gray, alkaline earth metal to grow. A new study published today in Environmental Science and Technology Letters shows that adding calcium to the soil can help reverse the decades-long decline of forests suffering from the effects of acid rain. The paper reports on 15 years of data from an ongoing field experiment in the Hubbard Brook Experimental Forest in New Hampshire:
“It is generally accepted that acid rain harms trees, but the value of our study is that it proves the causal link between the chronic loss of soil calcium caused by decades of acid rain and its impact on tree growth,” said study co-author Charles Driscoll Jr., professor of environmental systems engineering at Syracuse University. “The temporal and spatial scope of the study – 15 years and entire watersheds – is unique and makes the results convincing.”
The effects of adding calcium are not marginal. Compared to the control area, the study shows that the teated area had trees that produced 21% more wood and 1% more leaves. "The iconic sugar maple – the source of maple syrup – was the tree species that responded most strongly to the restoration of calcium in the soil."
This is particularly important because even if the Clean Air Act helped greatly reduce the quantity of acid rain in North America (it's a different story in China...), decades of it have left their mark on the soil and depleted calcium.
For the Hubbard Brook study, a helicopter spread 40 tons of dry calcium pellets over a 29-acre watershed over several days in October 1999. The calcium was designed to slowly work its way into the watershed over many years.
“This was restoration, not fertilization,” said Battles. “We were only replacing what was lost.” [...]
“The treatment increased the forest’s resilience to major disturbances,” said Battles. “The trees in the calcium-treated watershed were able to recover faster from a severe ice storm that hit the region in 1998.”
Sounds like many forests could use some calcium restoration, and this isn't something that would be expensive or hard to do. Once again, science FTW!
Via UC Berkeley