This fragmentation can impact farming in similar ways. From the standpoint of physical geography, fragmentation reduces the size of properties available for farming or ranching. When a 160-acre orchard here in Placer County is split into 5-acre lots - even if the trees remain - the economic viability of farming is seriously diminished. The story is similar for all types of farming and ranching. The scale of an operation is directly related to it's economic viability - a farm needs to produce enough product (and profit) to cover direct costs and overhead costs. An acre of vegetables, or 100 acres of unirrigated pasture, does not produce enough revenue for a farm family to make a living.
Beyond these economic impacts, fragmentation has logistical impacts as well. Using our own operation as an example, fragmentation can increase costs. We lease 20 acres of irrigated pasture that is less than a mile from 100 acres of annual rangeland that we also lease. Despite this proximity, these ranches are separated by 6 to 8 separate smaller properties. Before the intervening properties were subdivided, we could have walked our sheep from the irrigated pasture to the rangeland - a trip that would have taken about 30 minutes (at most). Today, since the landowners between our leased pastures don't want sheep tromping through their yards, we have to haul them in our trailer (or hire a semi to move them). This less direct route requires us to drive about 5 miles each way. Given the capacity of our trailer, moving our 300 sheep from one property to the other requires 12 trips (120 miles), a 12-hour day, and a significant amount of fossil fuel.
The third impact of fragmentation is to isolate farmers and ranchers from one another. In an earlier age, our neighbors would also be farmers. Today, we rarely run our sheep next to someone else who is also making their living from any kind of farming (let alone from sheep production). This isolation takes a toll in several ways. At one time, farmers learned (at least in part) from the successes and failures of their neighbors - you could see what was happening on the other side of your fence. The farming infrastructure (fences, canals, roads, etc.) was maintained by neighbors. Today, for example, most of our neighbors don't have livestock, so fence maintenance is not a priority for them.
I'm not sure what the solution to these issues might be. The conservation community has been effective at conserving larger landscapes and migration corridors to help avoid habitat fragmentation. Perhaps we need a similar approach to agricultural land conservation - we need to conserve whole "foodsheds" as well as watersheds. We also need to be honest about the scale of operation necessary for a farm or ranch to be economically viable.