Agricultural cropland occupies over 51,000 acres (2005) of the County and primarily located in the Napa Valley Floor, Carneros, and Eastern Mountains. Common agricultural croplands in Napa County are
- Forage crops (hay)
Vineyards occupy over 43,000 acres in Napa County (2017). Other minor croplands include forage crops, olives, a variety of orchards types, and nursery products. Note: pasture and rangeland have not been included in the totals in this section. The Napa County Crop Report annually lists the number of acres in agricultural production.
Vineyards are dominated by grape vines (Vitis spp.) and may contain permanent cover crop plants such as blando brome (Bromus mollis), or creeping red fescue (Festucarubra ssp. Rubra). Common weed species in vineyards include puncturevine (Tribulus terrestris), crabgrass (Ddigitaria spp.), and horseweed (Conyza Canadensis).
Olive orchards are dominated by European olive (Olea europea). Walnut orchards are dominated by Persian walnut (Juglans regia). The cover crops used in County orchards are similar to those used in vineyards, as are common weed species.
Hay fields are dominated by forage species such as alfalfa (Medicago sativa). Common weeds in hay fields include dandelion (Taraxacum officinale), quackgrass (Elytigia repens), and bermudagrass.
Vineyard grapes attract many birds, mammals, and insects. American robin (Turdus migratorius), European starling (Sturnus vulgaris), and house finch (Carpodocus mexicanus) are primary bird species that forage on grapes. Mammals include deer, raccoons and pocket gophers (Thomomys spp.).
The primary ecosystem functions of agricultural cropland in the County are:
- Provide food products for the human population
- Provide limited wildlife habitat
Use the map below to explore the various biotic communities throughout Napa County.