Scientists have noted a decline in fungi species dating back to the early 1900s. Annual crops of edible mushrooms in France and Germany have declined since 1950. One hypothesis to explain this decline is that edible fungi are being overharvested. Global warming and air pollution have also been considered as contributing to the decline. Which of the following would exclude overharvesting as the cause of the decline?
f Similar declines among edible North American species
g Fungal-population increases in tropical regions
h A parallel decline in non-edible species
j High fungal numbers in nitrogen-poor soils