A sign by the Giant Redwood (Sequoiadendron giganteum) in CUBG contains the following:

Carbon Offsetting
How many of my international flights could this tree offset?

CUBG has over 1,600 trees in its collection, with this being the largest.

This old Giant Redwood (Sequoiadendron giganteum), planted in the mid 1800s, locks a lot of carbon away in its wood. The amount of above ground carbon stored in a tree is a function of its wood density, height and stem diameter. Each year that a tree grows, it locks away more carbon into its wood. Although we mostly think of trees as carbon sinks, many become a carbon source in the later stages of their life due to decay. This 32 m giant redwood tree has a diameter of 190 cm and a wood density of 0.51 grams per cubic cm. Its above ground biomass has been calculated at 29 tons. It therefore stores 13.6 tons of above ground carbon.

This is equivalent to 49.9 tons of CO – that’s the same amount of CO, emitted by 8 people taking one return flight from London to Sydney in economy class.

It has taken this tree over 150 years to grow to this size and most don’t ever get this big!

It’s plain to see that offsetting flights by simply planting trees is not a sustainable solution to the problem. Nevertheless, tree planting is still beneficial, not only because of the additional CO, taken up by each new tree planted, but also for the biodiversity they are able to support. A single oak tree supports over 284 different insect species.”

Comment

Yes, we must reduce emissions, not least because along with CO and CO2 we are pumping out pollutants that are damaging everyone and everything they touch. But perhaps planting trees is more beneficial than the notice suggests. How about planting one hundred million trees? Eden Projects alone has planted over eight hundred million trees. And they are by no means the only charity planting trees worldwide. That scale of planting changes weather patterns, increases rainfall, stabilises the land. Look at the strip of forest either side of the Panama Canal for the effect of forests on climate.

Saw two foxes today at Cambridge University Botanic Garden. They were just a few feet from people standing watching them. A mallard couple in the stream didn’t seem to feel any need to move as the foxes came to the edge of the water.

One of the foxes had longer fur and was a little bigger than the other, but both were small. Were they are male and a female, perhaps? Young siblings perhaps?

More Chafer Grubs

On another topic, there were lots of fresh divots of grass and soil turned over on the main lawn – more crows after chafer grubs. From the number of divots of disturbed grass and soil, there must be a lot of. chafer grubs.

Cherry Tree

Also at Cambridge University Botanic Garden today, a Yoshino Cherry (Prunus x yedoensis) in bloom. The flowers are white when they are out, but tinged with pink when the buds are closed or just opening.

The Local Council replaced the two newly planted trees on Jesus Green here in Cambridge that didn’t make it through their first year. The two trees planted in their place are Cercis siliquastrum (Judas tree) and Liriodendron tulipifera (Tulip tree).

The generic name Cercis comes from the Greek kerkis, meaning a shuttle, which refers to the resemblance of the seed pods to a weaver’s shuttle. And siliquastrum means a pod. So really it is the pod-pod tree.

According to Wikipedia, the botanical name Liriodendron comes from the Greek and means a lily tree, And tulipifera which means to bring forth tulips, because its flowers resemble a tulip. In the right soil conditions it can grow to 55m and more. That will be a sight.

Speaking to one of the tree specialists at the Council a few days ago, he said that lack of water is the main cause of tree losses. And it is well nigh impossible to overwater a newly planted tree.