Arable weed diversity Arable weeds

So far, no nationwide data on the indicator “arable weed diversity” has been collected in Germany.

The graphic is an exemplary representation of the indicator "arable weed diversity," differentiated by arable crop type. As part of the MonViA project, data from the German states of Lower Saxony and Brandenburg were collected in 2022 as part of a proof-of-concept study. This non-representative data serves to test the developed monitoring methods and is available upon request. The number of arable fields examined in Lower Saxony and Brandenburg in 2022 varied between crops. 

The highest weed diversity was observed in rye and triticale, while only low diversity was seen in sugar beets. However, the sample size of 46 fields chosen for the proof-of-concept study was insufficient for the crops shown to achieve curve saturation and thus represent the full diversity of weed species occurring in each crop. Therefore, additional fields with different crops were examined in 2023 to adequately represent the indicator. Once monitoring has started, the indicator can be reported every three years.
 

The indicator "arable weed diversity" is composed of various data on weed occurrence, described using Hill diversity profiles. Here, "Na" represents the "effective number of species," "n" the number of species present, "q" defines the Hill factor, and "Pi" represents the relative abundance of a species. The effective number of species is a value that can be compared across different reporting levels and categories. Unlike traditional indices, the interpretation of these species numbers is intuitive.

          _n            ^1/(1-q)
N_a = (∑ P_i ^q)
         ⁱ⁼¹