Pinus ponderosa / Juniper us communis Plant Association 



PINPON / JUNCOM; ponderosa pine / common juniper 

 MTNHP rank G4/S3 



Environment: The PINPON/ JUNCOM is a recurrent forest type of the small BLM holdings on the 

 periphery of the Custer National Forest units in Carter County, though it makes up a small area. Two 

 stands were sampled on BLM parcels on the periphery of the Ekalaka Hills and at the Belltower 

 Butte. Stands are generally ensconced below rimrocks of sandstone capped tablelands, favoring 

 steep (40 % plus) northern aspects, representing small areas with natural firebreaks. 



Vegetation: The presence ofJuniperus communis, a species easily killed by fire, in this plant 

 association is diagnostic (Hansen and Hoffman 1988). Absence of fire scars and development of a 

 thick litter layer are indications of a long fire interval in this community where sampled on BLM in 

 the Ekalaka Hills. In contrast, evidence of past fires is common in stands of the two adjacent forest 

 communities, PINPON/CARINO and PINPON/PRUVIR (Hansen and Hoffman 1988). Ponderosa 

 pine itself is resistant to fire, resistance increasing with tree age and bark thickness. 



In the two plots sampled, cover by Pinus ponderosa is about 50%. Cover by the dominant shrub 

 Juniperus communis, ranges fi-om 20 to 50%. The shrubs Mahonia repens and Prunus virginiana are 

 also well represented in both plots. Graminoid cover barely exceeds trace amounts, far less than that 

 of shrubs, but includes species {Carex backii, Schizachne purpurascens) which are not found outside 

 of forest and woodland habitats in Carter County. Forb cover and diversity is also relatively low but 

 includes species (Maianthemum stellata, Disporum trachycarpum) unique to these relatively mesic 

 forest or woodland habitats 



On the tops of the Ekalaka Hills sampled by Hansen and Hoffman (1988), PINPON/JUNCOM 

 occurs on gentle terrain in a mosaic with Pinus ponderosa/Carex inops (PFNPON/CARINO) and 

 various grassland communities. Positions more mesic than that of our sampled plot in the Ekalaka 

 Hills (generally downslope and more ravine-like settings) grade towards Pinus ponderosa/Prunus 

 virginiana (PfNPON/PRUVIR) and drier sites of Pinus ponderosa/Pseudoroegneria spicata 

 (PINPON/PSESPI). Very limited extents of all four of these ponderosa pine associations occur on 

 BLM land. 



Soils: Parent materials are sandstones or sandstones with some admixture of colluvial shale; they 

 have weathered to sandy loams and sandy clay loams. As with most of the forested environments 

 sampled soils are distinctly more acidic than those of rangelands (with exceptions for extraordinary 

 substrates, such as bentonite clays.) These soil parameters are in accord with the values found by 

 Hansen and Hoffman (1988). 



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