Question

some climate models predict that the habitat ranges of north american trees will expand northward as average temperatures warm. however, some tree species, like sand post oaks and spruce pines, havent expanded. this is called \migration lag\ - when species fail to expand their range, even when conditions seem right. scientists have proposed several possible explanations: fewer species of soil fungi available at the northern edges of the trees habitat, physical barriers blocking seed dispersal, or deer overgrazing preventing new trees from establishing. 8 mark for review according to the text, what unexpected phenomenon are scientists observing in north american tree species? a some north american tree species arent increasing their habitat ranges despite suitable climate conditions. b the ranges of sand post oaks and spruce pines are expanding more rapidly than climate models predicted. c some north american tree species are developing resistance to fungal partnerships at the northern boundaries of their ranges. d the ranges of sand post oaks and spruce pines are primarily expanding southward instead of northward.

Explanation:

The text mentions that some climate models predict north - ward expansion of North American tree habitats as temperatures warm, but some tree species like sand post oaks and spruce pines haven't expanded, despite seemingly suitable conditions, which is called "migration lag". Option A correctly states this unexpected phenomenon. Option B is contrary to the text as these species haven't expanded. Option C is not mentioned in the text. Option D is also not in line with the text as there is no mention of south - ward expansion.

Answer:

A. Some North American tree species aren't increasing their habitat ranges despite suitable climate conditions.