The Pinegrass complex is dominated by pinegrass, but it may include minor amounts of arctic lupine and other species. In southern interior British Columbia, the Pinegrass Complex is most abundant on dry to fresh sites in the IDF and MS biogeoclimatic zones, but it also occurs in drier subzones of the ICH, SBS, and ESSF zones. Pinegrass occurs across a range of nutrient regimes, and is common on sites with nutrient deficiencies.

Pinegrass cover and root development escalate in response to increased light availability following harvesting, and also in response to the light to medium soil disturbance associated with harvesting, low-impact mechanical site preparation, and low- to medium-intensity fires. Most pinegrass roots are found in the top 5 cm of soil, so severe disturbances slow development of the Pinegrass complex.

Pinegrass produces abundant roots and rhizomes and grows quickly in the early spring when water is most abundant. These characteristics make it a strong competitor with conifer seedlings for soil water. Seedling performance is often poor in the presence of the Pinegrass complex, but soil water is not always the most limiting factor. On some sites, nutrient deficiencies and low soil temperature may be more limiting than water. Dense pinegrass cover may also increase the incidence of frost damage to young seedlings by insulating soil against warming during the day and trapping cold air at seedling height at night.

Typical development of the Pinegrass complex 7 years after mechanical site preparation.