Soil properties associated with vegetation patches in a Pinus ponderosa-bunchgrass mosaic

Becky K. Kerns, Margaret M. Moore, Michael E. Timpson, Stephen C. Hart

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Since Euro-American settlement, fire exclusion and other factors have dramatically altered interior western coniferous forests. Once open and parklike, present-day structure in many southwestern Pinus ponderosa forests consists of dense stands of young, small-diameter trees, with small patches of larger, old trees, and relict open bunchgrass areas. Our objectives were to assess differences in soil properties associated with these different vegetation patches. We examined soil morphological characteristics, pH, organic C concentration, total N concentration, C:N ratio, and phytolith concentration from profiles within 6 transects (18 soil pedons) crossing patches of dense stands of small-diameter trees, patchs of old-growth trees, and open grassy areas. Results indicate that old-growth plots had significantly lower A horizon pH and thicker O horizons than grass plots. In general, we found vegetation patches had statistically similar C and N concentrations and C:N ratios for A and B horizons; however, C in the A horizon was positively correlated with O horizon accumulation (r2 = 0.79). Greater accumulation of organic C in the A horizon of forested areas contrasts with commonly reported results from mesic, mid-continental prairie-forest ecosystems but is typical for many arid, semiarid, and humid savanna ecosystems. Phytolith concentration was similar among old-growth pine, dense younger pine, and open grassy plots; the lack of a spatial pattern in phytolith distribution could indicate that grass cover was more spatially continuous in the past. Additionally, this interpretation is consistent with current theories regarding historical vegetation change in these forests.

Original languageEnglish (US)
Pages (from-to)452-462
Number of pages11
JournalWestern North American Naturalist
Issue number4
StatePublished - Oct 2003


  • Biosequence
  • Forest soils
  • Grassland soils
  • Nonmetric multidimensional scaling
  • Phytoliths

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology


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