The good news, according to redwood ecologist Dr. Emily Burns, is that climate change seems to be working in Redwoods favor — for the moment at least, doing a lot of carbon sequestration. Over the last century growth rates are increasing for Redwoods all over California but Northern California in particular. No one knows the answer but leading answers are longer growing seasons, less fog/more sunshine, and more CO2.
But it’s difficult to say if that will last, or it will be good in some places and bad in others, the Redwoods live amongst and between many microclimates. Redwoods demand a pretty high volume of water — and if the amount of fog continues to decrease (fog has decreased by ~33% over the last century) it’s hard to say when redwoods might feel the pinch. Scientists do not know what the tipping point would be.
Redwoods, and 80% of the plants that live within a redwood forest, take in much of their moisture through their needles and leaves through a process called foliar uptake. The amount of water they get is dependent on how much fog sticks around, but the process is readily visible if you are climbing into a redwood when the fog comes in — as Dr. Burns attested from her experience up in the trees.
Overall, the last 144 million years have been a rough period for redwoods. There has been a massive reduction in their population since the Jurrasic, their range contracting due to a combination of geological and climatic changes. Of course, the last couple centuries has seen the last remnants of redwood forests under immense pressure from mankind’s agriculture and urbanization.
The 2009 Redwoods and Climate Change Initiative has set out to study the last 30 years of Redwood history, and compare it against the 1900-1980 historical baseline that we have, to try to make predictions, and understand the patterns that are driving change in the area — and how that will affect Redwoods. This is done through historical records, but most importantly the redwoods own record — it’s tree rings.
Tree rings give a picture of how a tree has done over the years. Tree ring studies have been around a long time, but redwoods are notoriously difficult. Researchers have taken care to take cores from different heights, and cross reference them both across the tree and across forests looking for patterns.
One thing that they’ve been able to see with these kinds of studies is how trees respond to droughts and floods. The tree record shows that the response is immediate. All this data is being submitted to a national archive, and plans are afoot to compare data across species.
Researchers are also measuring branches — 40% of growth occurs in branches. And these big trees can grow! The superstar tree is the Emerald Giant which produces wood sufficient for 2 million pencils in a year. Once they thought old trees grew slower because their tree rings got thinner — but it turns out it is just the tree putting more wood over a greater surface area. Old trees it turns out, grow faster.
Of course, climate change also affects more than just the Redwood tree, but the whole Redwood forest ecosystem. Maybe the trees grow well, but what if the rest of the forest plants don’t cope as well… what would happen then. The forest is a very complex ecosystem — and there is a lot more data to be had.
Dr. Burns invites everyone to join in to help with the Redwoods. One simple thing, is to help find them all — look for the Redwood Watch iPhone app.
You can also find out more about Dr Burns work at her website, or by following her on twitter.
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