Speaking after one decade of experience in  northern Italy, small and/or non-professional farmers operating in marginal areas (pre-alpine valleys, small Mediterranean isles etc.) show most interest in growing and often collecting landraces. Conversely, large or medium size farms are often absent, as the industrial agriculture they practice an obstacle to (re)introduce  landraces in their cropping systems.  Conversely, small and/or non-professional farmers  are not familiar with cropping systems;  unfortunately  they are often aged,  so the perspectives  about landrace  and agrobiodiversity conservation (at least in in Italy)  rely on activities carried out by  local agricultural agencies. As you may probably know, the International Treaty on Plant Genetic Resources for Food and Agriculture (Rome, 2001) set the scene for these  PGR  topics at global level.

there are some methods to measure biodiversity on different farm scale. It could be masured as how the farmers in one community use their landscape. Usually measuring biodiversity in farm scale also related to measuring carbon stock, optimize yield potential by different crops, and the sustainability of agroecology in a farm scale.

I'm studying a lot of thing about this topic from my lecture, may you ask her for more detail discussion. 

https://www.researchgate.net/profile/Kurniatun_Hairiah/publications