As greenhouse gas levels rise and global temperatures warm spring is arriving ever earlier. And the growing season in northern hemisphere is now two weeks longer than it was in 1900. But new research shows, paradoxically, that forest giants that once responded to the early spring are beginning to slow down as they miss the chill. An earth system scientist at Peking University, Beijing, named Yongshuo Fu and his colleagues report in Nature journal that they have measured a slowdown in the response of forest citizens including oaks to the change in temperatures and carbon dioxide levels. According to Climate News Network news received from London on October 04, 2015 where these species, on an average, with every 1 degree Celsius rise in temperature unfolded their first leaves four days earlier, they now do so only 2.3 days earlier for every additional 1 degree Celsius.
The reason is that, these deciduous species first need to feel a period of chill, to take full advantage of the ever-earlier spring. But the extent of true winter chill diminishes as temperatures on average rise. The nature researchers concede that there may be other or additional reasons why silver birch (Betula pendula), alder (Alnus glutinosa), beech (Fagus sylvatica), horse chestnut (Aesculus hippocastanum), oak (Quercus robur), ash (Fraxinus excelsior) and lime (Tilia cordata) seem to be slowing in their leafy response. But it seems a likely factor since many deciduous trees depend on a frosty spell to release them from their periods of dormancy.
The nature researchers used data from the Pan-European Phenology Project to identify the slowdown. The Pan-European Phenology Project for 33 years has monitored the unfolding of the first leaves of all seven species mentioned above at 1,245 sites across central Europe. The human beings, as a consequence of the combustion of fossil fuels, change the climate by increasing carbon dioxide levels in the atmosphere. They are also changing the ecosystems that support all life on Earth. The scientists used direct observation, and confirmed this hypothesis once again with computer models to show that this is true. And the US scientists in the same week reported that the pollinating insects too are beginning to respond as global warming begins to change the mix of mountain wildflowers each spring.
A biologist at the State University of New York named Nicole Miller-Struttmann and his colleagues report in Science journal that the tongues of two species of alpine bumblebee have grown shorter in the last 40 years. To reach deep into the flower tubes of the plants they favour, the bumblebees need long tongues. But warmer summers have meant that the flowers they favour most in the Rocky Mountains have become less frequent. As a result the pollinators that once specialised have now become generalist foragers, grabbing honey from where they can. In the course of doing so, two species of alpine bumblebees that are commonly found at high altitudes species - Bombus balteatus and Bombus sylvicola - have evolved shorter tongues. In consequence, the mix of flowers at lower altitudes has become impoverished. And although mountain flowers have been gaining altitude over the decades, the gain in higher growth has not been enough to offset the loss for the bees.
The research confirms a wider picture of change in plants species as a consequence of global warming. Plants are colonising higher slopes in the Americas, while the bumblebee has also been feeling the heat in Europe, and losing part of its tongue's range. In general, high altitude sites seem to be warming faster than the low altitude lands. Research of this kind provides a local snapshot of global change of plats and pollinators species. And what it means for individual plant species in nature's mix. The scientists conclude that "We see broader bumblebee foraging niches, immigration by short-tongued bumblebees, and shorter tongue length within resident bee populations as floral resources have dwindled. In Remote Mountain habitats largely isolated from habitat destruction, toxins, and pathogens evolution is helping wild bees keep pace with climate change".
To save the nature along with its floral resources - at high or low altitude or plain lands - and its catalytic biological agents pollinators species to help sustain and continue nature's normalcy of existence and behaviour, human beings are to restrain themselves from doing harm to ecological balance of the planet earth, by reducing or eliminating combustion of fossil fuels that change the climate by increasing carbon dioxide levels in the atmosphere. The results of human beings' imprudent habit of neglecting the adverse impact of their callous march forward with reckless material development are already being felt. The time is, probably, not so far away when humans' all efforts for mundane material development, by any means, will boomerang on them. Let human species beware.
The writer is a retired Professor of Economics, BCS General Education Cadre.
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