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The nectar resource in a given area depends on the kinds of flowering plants present and their blooming periods. Which kinds grow in an area depends on soil texture, soil pH, soil drainage, daily maximum and minimum temperatures, precipitation, extreme minimum winter temperature, and growing degree days. The plants listed below grow in USDA Hardiness zone 5. A good predictor for when a plant will bloom and produce nectar is a calculation of the growing degree days. (Hopkins' Bioclimatic Law ) states that in North America east of the Rockies, a 130 m (400-foot) increase in elevation, a 4° change in latitude north (444.48 km), or a 10° change in longitude east (two thirds of a time zone) will cause a biological event to occur four days later in the spring or four days earlier in the fall. In botany, the term phenology refers to the timing of flower emergence, sequence of bloom, fruiting, and leaf drop in autumn. The classification in major or minor nectar source is very dependent on the agricultural use of the land. An agricultural crop such as canola or alfalfa may be a major or minor source depending on local plantings. Generally, the more diverse a forage area is, the better for a stationary apiary. Urban, suburban and areas not under cultivation provide more consistent warm-season nectar forage than areas that are heavily cultivated with only a few agricultural crops. The nectar sources from large cultivated fields of blooming apples, cherries, canola, melons, sunflowers, clover etc. benefit a bee keeper who is willing to travel with his hives throughout the season. Honeydew sources are not included in this listing. ==Trees and shrubs== ==Flowers, crops, herbs and grasses== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Northern American nectar sources for honey bees」の詳細全文を読む スポンサード リンク
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