Quaking Aspen (Populus tremuloides) reproduce via rhizomes, creating immense colonies that may include thousands of trees. One colony in Utah, nicknamed Pando, consists of a grove of ~47,000 trunks. Despite their massive size, scientists worry that these stands are vulnerable–why?

These strands are clones, however, due to their low genetic variability, the population becomes susceptible to diseases taking place in plants. Pando comprises grove of about 47000 trunks, these all are genetically similar that develops from a solitary underground species, Quaking aspen tree. Pando is an extremely large clone.  

However, for the past some years, scientists are worried about Pando's health. For the past thousands of years, Pando was living in fine tune with the native wildlife population, but for the past some years, a shift in balance is noticed. As in the absence of the development of novel stems, nothing will be able to substitute the natural withering of the older ones, if this goes on, the death of Pando will take place.  

the correct answer, according to e2020, is the second choice there is an occluded front in region a and a cold front in region b.

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