In this study a group of researchers were trying to find a mechanism or cause behind the effects of increased nitrogen disposition on fauna diversity. The researchers specified that  there had been plenty of studies done on correlational relationships between the N deposition and soil acidification and the growth of plants like algae, but there wasn’t very much on the mechanisms causing the changes in those ecosystems in any part of ecosystem ecology. But, even with their own evidence gathered from various effected an less effected areas of increased nitrogen, there was still not enough to come to a conclusion, so more studies will need to be conducted. Though they did find six mainly indirect bottlenecks that my be behind some of the mechanism behind the changes in the ecosystems due to increased nitrogen deposition.

The six bottlenecks discussed and investigated in the study were: chemical stress, a leveled and humid microclimate, decrease in reproductive habitat, changes in food plant quantity, changes in nutritional quality of food plants and changes in availability of prey or host species due to effects in the food web. The researchers found that depending on species and habitat type, different pathways play a dominant role and interference between different pathways can strengthen or weaken the net effect of Nitrogen deposition.

The research problem discussed in this piece of research was why the fauna were reacting to changes in Nitrogen deposition differently and what the driving force was. And which of the possible bottlenecks was the most prominent. The data type was most likely detached observation reports of past research on related or similar topics  Though this study did not include vary many tables or numbers for their paper, which could mean that the study was not as thorough as it could have been, but the researchers did say that  all bottlenecks were supported by peer reviewed literature, scientific evidence on the causal relationship between increased N deposition and effects on fauna in the complete causal chain was insufficient and that further research was needed. The biggest gap in knowledge  were about subtle changes in plant chemistry and changes in availability of prey and host species to higher trophic levels.

Nijssen, M. E., M. F. WallisDeVries, and H. Siepel. “Pathways for the effects of increased nitrogen deposition on fauna.” Biological Conservation(2017).