Declining plots tend to produce less. Often these vines are simply less bountiful, but more often than not it is because unproductive, diseased or young vines need to be removed from the equation.
The productivity rate on some plots may have only be around 75%.
Areas with significant replantation
A 40 hl/ha yield may not necessarily correspond to 7500 or 100000 vines per hectare, because vineyard management from one estate to another can vary.
Arguably, there is a critical point, that once attained, serves as an additional argument to demonstrate that the parcel has reached a point of non-profitability and should therefore be replanted. Next, it's important to consider the working cost of the plot, current yield compared to potential yield as well as potential yield when replanted.
On each plot, a theoretical qualitative potential can be determined. One must consider the topography, the water regime, the type of soil (granulometry, possibility of deep rooting, CEC...). By combining this information with the grape varietals planted, we can estimate the terroir's overall "quality".
When the quality is not currently being met, it would indicate that cultivation practices and/or the plant material (rootstalk/graft) are ill-suited to the plot's soil type.