Question

why does the plant biomass of Agrostis canina stop/cease with increasing nitrogen, when other plants continue to gain biomass with increasing nitrogen? i think it has something to do with the principle of allocation and adaption.

Answer 1

Yes, it is related to adaptation, there are certain plants that are adapted to grow in soil which is low in nutrients. These plants have the ability to grow well as other species which require nutrient-rich soils. Since Agrostis canina is adapted to low nutrient conditions, its growth will cease when either medium or high nitrogen levels are provided. Hence there is a decrease in its biomass or we can say it is not adapted to take advantage of excess nitrogen present in the soil.