Speaking for the TreesEarlier in the month, I wrote a post about the beautiful Muir Woods just north

Speaking for the TreesEarlier in the month, I wrote a post about the beautiful Muir Woods just north of San Francisco, but times have been hard for the Muir redwoods and other large trees in California recently. A new study of the health of California’s forests found that 58 million of California’s large trees have been dangerously stressed by the state’s long drought, suffering severe water loss since 2011. The study by Carnegie used satellite data as well as spectroscopy imaging from the Carnegie Airborne Observatory (CAO), a fixed-wing aircraft which uses laser scanning to create 3D maps of vegetation.The CAO was mounted with sensors for high-fidelity imaging spectroscopy (HiFIS), which measures spectral radiance from the land surface to identify biologically important elements and compounds. This includes measurements of liquid water in foliage, or “canopy water content”. The spectroscopy results are then compared to the 3D imaging to exclude non-forest foliage and bare land from the data set. By mapping changes in canopy water content, scientists can assess the areas of forest that are under highest drought stress, and therefore at the most risk for death and fire hazard. The image below shows the progressive canopy water stress for the 2011-2015 period, calculated as the total percentage of canopy water content loss.The effect of the drought has been dramatic; 888 million trees - 41,000 square miles of forest - have experienced water loss, and the losses for 58 million of those trees are considered extremely threatening. The impacts on long-term forest health may be extensive. Although the El Nino has had at least one positive effect in increasing the rain in California, the weakened forest systems will still be vulnerable to any return to drought conditions. The consequences for California could be significant; besides the ecological impacts and the threat to endangered species like the redwoods, California’s forests are an important economic factor for tourism, recreation, and timber products. -CELImage: Asner et al, 2015.Source: Asner et al, 2015. http://bit.ly/1UkR9Dbhttp://bit.ly/22CJvu5 -- source link
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