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Pinus ponderosa Observations
(ponderosa pine)
Submit Data Observations
Introduction to the NPN Native Species Observation Program
Ponderosa pine (also called western yellow pine) is one of the most widely distributed pines in western North America. A major source of timber, ponderosa pine forests are also important as wildlife habitat, for recreational use, and for esthetic values. Throughout the range of ponderosa pine, soil moisture is the variable most often limiting growth, especially in summer when rainfall is deficient. Ponderosa pine grows on a wide variety of soils. Its distribution on drier sites is related closely to supplies of available soil moisture which, in turn, are related to soil textures and depth. Ponderosa pine is monoecious. At pollination the male strobili, borne in short, dense clusters, are 2 to 3 cm (0.8 to 1.2 in) long and female conelets are 2.5 cm (1 in) long. Flowering is correlated closely with the passing of freezing weather.
Source: Silvics of North America, Volume 1: Conifers
You should record when two well-defined phenological events occur for ponderosa pine:
- Needle appearance (NA) Beginning of needle appearance (May shoot) is the date when first buds have burst open in at least three places on the plant under observation, but scales are still peeling off from the bud's exteriors. In this stage portions of the scales are still partially covering the not yet expanded needle bunches.
- Flowering (CF) This is the date when the flowers of male (staminate) inflorescence are open in at least three places on the plant under observation, and begin to release yellow pollen.
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Please record average dates for each event among multiple plants of the same species. Report by email if any plant appears in poor health or event dates for same-species plants vary by more than a few days.
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