Thursday, October 1, 2015

Trees and Diversity

In a recent Nature article the authors estimate the number of trees on the globe. Their conclusion is:

The global extent and distribution of forest trees is central to our understanding of the terrestrial biosphere. We provide the first spatially continuous map of forest tree density at a global scale. This map reveals that the global number of trees is approximately 3.04 trillion, an order of magnitude higher than the previous estimate. Of these trees, approximately 1.39 trillion exist in tropical and subtropical forests, with 0.74 trillion in boreal regions and 0.61 trillion in temperate regions. Biome-level trends in tree density demonstrate the importance of climate and topography in controlling local tree densities at finer scales, as well as the overwhelming effect of humans across most of the world. Based on our projected tree densities, we estimate that over 15 billion trees are cut down each year, and the global number of trees has fallen by approximately 46% since the start of human civilization.

 Now I decided to map my small patch of land in New Jersey, about 13,000 sq feet. Some 2,000 sq feet is my Hemerocallis "Lab" where we do genetic research. There is a house, a driveway and some 124 trees. Yes, some 124 trees, of some 32 different species. I have the densest collection of Ginkgos and Metasequopia in North America. Did not know that until I did the count. Both from China and both extinct in nature. And both bearing seed and quite healthy.

The above is the details. Now if we compare this to the Nature article we see:
Note that from the above Nature date our density of 928 trees/Hectare is well near the highest level on the chart.

So what does this say? Well we humans are lovers of plants, in my case specimen trees and Hemerocallis. We have managed to repopulate near extinct species.

There may be hope after all.