The impact of Indigenous populations on historical fire regimes has been controversial and beset by mismatches in the geographic scale of paleofire reconstructions and the scale of land-use behaviors. It is often assumed that anthropogenic burning is linearly related to population density and not different cultural practices. Here we take an off-site geoarchaeology strategy to reconstruct variability in historical fire regimes (<1000 years ago) at geographic scales that match the archaeological, ethnohistorical, and oral tradition evidence for variability in the intensity of Indigenous land use by two different cultural groups (Ancestral Pueblo and Western Apache). We use multiple, independent proxies from three localities in ponderosa pine (Pinus ponderosa) forests in east-Central Arizona to reconstruct fire regime variability during four phases of cultural use of different intensities. Elevated charcoal with domesticate pollen (Zea spp.) but otherwise unchanged forest pollen assemblages characterized intensive land use by Ancestral Pueblo people during an early phase, suggesting fire use to support agricultural activities. By contrast, a phase of intensive pre-reservation Western Apache land use corresponded to little change in charcoal, but had elevated ash-derived phosphorus and elevated grass and ruderal pollen suggestive of enhanced burning in fine fuels to promote economically important wild plants.

Experiments are conducted to evaluate the tolerance of three deciduous species: black locust, honeylocust, apple, and three coniferous species: Douglas fir, ponderosa pine, and Japanese black pine, in the seedling stage to napropamide. Deciduous species were more susceptible to napropamide than coniferous species. Domestic apple had the slowest seed germination and root development and was more susceptible. The deciduous species had more secondary roots in the shallow soil layer which contained most of the herbicide than the coniferous species. The roots of all woody species tested in vitro were inhibited significantly by contact with the herbicide, but only shoot growth of domestic apple and black locust was inhibited. Injury to woody nursery crop seedlings may be avoided by delaying herbicide application.

Correlations between herbicide damage and several physiological factors were examined in the field for ponderosa pine (Pinus ponderosa Dougl. ex P&C Lawson) and greenleaf manzanita (Arctostaphylos patula Greene). Pine injury caused by 2,4-D [(2,4-dichlorophenoxy) acetic acid], glyphosate [N-(phosphonomethyl) glycine], or triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid]} was compared to leader growth rate, needle growth rate, predawn xylem potential, daytime xylem potential, and photo synthetic rate occurring on the dates of herbicide application. Shrub injury for each of the three herbicides was compared to predawn xylem potential, daytime xylem potential, and photo synthetic rates. Both species exhibited less injury from herbicide applications made at the end of September than from any applications made from April through October. Comparison of factors highly correlated to herbicide damage indicates that highest herbicide selectivity occurs when pine has ceased growing, the xylem potential of the pine is relatively low (high water stress), and the xylem potential of the manzanita is relatively high.

Seven herbicides and two herbicide combinations were applied once either preplant or postplant to control perennial grasses and forbs as planting-site preparation for 2-yr-old seedlings of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and Douglas fir [Pseudotsuga menziesii var. glauca (Beissn.) Franco] at locations in Washington and Oregon. Hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H, 3H)-dione] applied at 2.2 kg/ha provided most effective and lasting herbaceous weed control in both states. A combination of dalapon (2,2-dichloropropionic acid) and atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] applied at 9.0 + 4.5 kg/ha also proved similarly effective. In Washington, each conifer species responded with exponential growth increases over a 6-yr period. For ponderosa pine and Douglas fir, respectively, hexazinone treatment increased tree height by 58 and 70%, stem diameter by 70 and 69%, and stem-volume yield by 387 and 650% as compared to untreated checks. Corresponding gains for the two conifers associated with dalapon + atrazine were 73 and 54% in height, 63 and 46% in diameter, and 421 and 349% in yield.

The morphology and anatomy of ectomycorrhizas of Rhizopogon arctostaphyli, R. ellenae, R. flavofibrillosus, R. occidentalis, R. rubescens, R. smithii, R. subcaerulescens and R. truncatus synthesized on Ponderosa pine (Pinus ponderosa) in glasshouse conditions using spore slurries, are described and compared. All species produced a well-developed Hartig net, and a well-developed fungal mantle. The mantles of R. arctostaphyli, R. smithii and R. subcaerulescens ectomycorrhizas were two-layered with outer mantle hyphae of wider diameter than inner mantle hyphae. The mantle of R. subcaerulescens ectomycorrhizas also had distinctive peg-like structures (cystidia) along peripheral hyphae. Rhizopogon truncatus ectomycorrhizas were tuberculate in morphology and had a rind-like mantle enclosing adjacent roots. In addition, several species exhibited crystal inclusions in the outer mantle, presumably at the interface between mantle and soil.

Seedlings of Pseudotsuga menziesii (Mirb.) Franco, Pinus ponderosa Dougl. ex Laws, Arbutus menziesii Pursh., and cuttings of Arctostaphylos uva-ursi (L.) Spreng were grown in monoculture and in conifer-hardwood dual-culture combinations in the glasshouse and inoculated with spore slurries of six Rhizopogon species. The primary objectives were to assess and compare the pattern of host specificity between symbionts and to study the influence of co-cultured plants on ectomycorrhiza development. The Rhizopogon spp. ranged from genus-specific to multiple-host compatible. In monoculture, four Rhizopogon sp. (R. ellenae Smith, R. occidentalis Zeller & Dodge, R. smithii Hosford and R. subcaerulescens Smith) formed ectomycorrhizas with Pinus ponderosa, and two Rhizopogon sp. (R. parksii Smith and R. vinicolor Smith) formed ectomycorrhizas with Pseudotsuga menziesii. None of the fungi tested developed ectomycorrhizas on Arbutus menziesii or Arctostaphylos uva-ursi in monoculture. In dual culture, three of the four Rhizopogon species (R. ellenae, R. occidentalis and R. subcaerulescens) that formed ectomycorrhizas on Pinus ponderosa, formed some ectomycorrhizas on Arbutus menziesii and Arctostaphylos uva-ursi. Rhizopogon parksii and R. vinicolor only formed ectomycorrhizas on Pseudotsuga menziesii.