Total carbon and nitrogen in mineral soil after 26 years of prescribed fire: Long Valley and Fort Valley Experimental Forests

Prescribed fire was introduced to high density ponderosa pine stands at Fort Valley and Long Valley Experimental Forests in 1976. This paper reports on mineral soil total carbon (C) and nitrogen (N) at Long Valley. Total soil C and N levels were highly variable and exhibited an increasing, but inconsistent, concentration trend related to burn interval. Total N ranged from 0.1 to 0.45%. Randomly collected soil sample C ranged from 2.2 to 5.7%, but stratified sampling indicated a greater total C range from 1.7 to 11.5%. Random sampling allows scaling up to stand and landscape level but stratified sampling does not. The latter provides an index of C and N variability due to stand conditions (old growth, polesized stands, and ponderosa pine thickets), clearings devoid of trees, or heavy woody debris accumulations.