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Greenhouse-cultured, container-grown ponderosa pine (Pinus ponderosa var. scopulorum Engelm.), interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco), and Engelmann spruce (Picea engelmannii (Parry) Engelm.) were cold acclimated and deacclimated in growth chambers over 19 weeks. Cold hardiness was measured weekly by a whole-plant freeze test and by two quick tissue tests: freeze-induced electrolyte leakage of needles, and differential thermal analysis of buds. The whole-plant freeze test provided results in 7 days, and indicated differences in cold hardiness among stems, buds, and needles. Although the whole-plant freeze test could accurately measure cold hardiness, it was not precise, and it required destructive sampling. Results from freeze-induced electrolyte leakage and differential thermal analysis were available in 2 days and 1 hour, respectively. The freeze-induced electrolyte leakage test was a precise, sensitive and objective predictor of changes or differences in tissue cold hardiness. To determine actual cold hardiness, results could be calibrated to the response of the same tissue in the whole-plant freeze test. The speed and objectivity of differential thermal analysis made this test useful for rapid, general assessment of cold hardiness status, but calibration was difficult, and precision varied.

A response surface design was used to help define the "nutritional niche" of the western spruce budworm, Choristoneura occidentalis. We evaluated how calcium, magnesium, and phosphorus interacted to influence budworm fitness on artificial diets containing five different levels of the minerals. We quantified survival rates for several life stages using a three—generation bioassay. Data from the bioassay were used to estimate population growth over three complete generations. Performance of the budworm was affected by Mg (linear response for F1 generations; 0.83—1.95 mg/g tested) and P (quadratic response for P1 [parental] and F1 generations; 2.74—4.95 mg/g tested) but was largely unaffected by Ca (0.50—6.81 mg/g tested). Overall, the results suggested budworm performance is best when Mg is at low concentrations and P is at moderate concentrations, and that very high levels of Mg and P are detrimental to the budworm. On average, host trees had too much Mg and too little P for optimal response by budworms. Interactions between Mg and P imply that balances or ratios of minerals are important in budworm nutritional ecology. However, detectable effects from Mg, P, and Ca in the diets diminished as the bioassay continued into the F2 generation, and, consequently, the estimated number of larvae alive at the beginning of the F2 and F3 generations showed no relationship to concentrations of the test minerals. This result probably reflected: (1) the loss of some design points in the second and third generations of the biomass because larvae did not survive on diets that were markedly suboptimal and (2) increased variability in the population growth response as the experiment contributed into the F2 and F3 generations.

Land management activities can result in the delivery of fine sediment to streams. Over time, such delivery can lead to cumulative impacts to the aquatic ecosystem. Because numerous laws require Federal land managers to analyze watershed cumulative effects, field personnel need simple monitoring procedures that can be used directly and consistently. One approach to such monitoring is described. The approach involves sampling a longitudinal reach of stream channel several hundred feet long using a zigzag pebble count procedure that crosses all habitat features within a stream channel. The approach accommodates reference (unimpacted) and study (impacted) reaches so that impact comparisons can be made. Case studies show how the procedure is applied.