Complex sentence: Immigration by short-tongued bumble bees toward higher altitudes has also occurred as a result of warming and climate change, and has created new competition for "Bombus balteatus" to ascertain limited floral resources.
Split into simpler sentences: Immigration by short-tongued bumble bees into higher altitudes has also occurred as a result of warming and climate change. This creates new competition for "Bombus balteatus" for limited floral resources.