Over-crowding in seedlings of different species is less serious than over-crowding involving one species because different species may

Overcrowding in plants can lead to competition for resources such as water, nutrients, and sunlight. When seedlings of different species are overcrowded, there is less competition for resources because the different species may have different nutritional needs or be active at different times. This means that each species can obtain the necessary resources to grow and develop without being hindered by the other species. On the other hand, when overcrowding involves one species, they will be in direct competition with each other since they have similar nutritional needs, and this can hinder their growth and development. Therefore, overcrowding in seedlings of different species is less serious than overcrowding involving one species.