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Survival patterns after late summer wildfires were evaluated for Douglas-fir and lodgepole pine in the northern Rocky Mountains. Crown scorch was the most important variable for predicting postfire survival and variables representing bole damage improved the significance of logistic regression models for both species. Crown scorch and basal scorch were the best combination of variables for predicting survival in lodgepole pine. Crown scorch and insect damage were the best combination of variables for predicting survival in Douglas-fir. Postfire survival of lodgepole pine, which has relatively thin bark, was more sensitive than Douglas-fir to variables that quantified bole damage.

Measurement of ionic deposition in throughfall is a widely used method for measuring deposition inputs to the forest floor. Many studies have been published, providing a large database of throughfall deposition inputs to forests. However, throughfall collection and analysis is labor intensive and expensive because of the large number of replicate collectors needed and because sample collection and chemical analyses are required on a stochastic precipitation event-based schedule. Therefore we developed and tested a throughfall collector system using a mixed bed ion exchange resin column. We anticipate that this method will typically require only one to three samplings per year. With this method, bulk deposition and bulk throughfall are collected by a funnel or snow tube and ions are retained as the solution percolates through the resin column. Ions retained by the resin are then extracted in the same column with 2N KCl and analyzed for nitrate and ammonium. Deposition values in throughfall from conventional throughfall solution collectors and colocated ion exchange samplers were not significantly different during consecutive 3- and 4-month exposure periods at a high (Camp Paivika; >35 kg N ha-1 year-1) and a low deposition (Barton Flats; 5–9 kg N ha-1 year-1) site in the San Bernardino Mountains in southern California. N deposition in throughfall under mature pine trees at Camp Paivika after 7 months of exposure was extremely high (87 and 92 kg ha-1 based on the two collector types) compared to Barton Flats (11 and 13 kg ha-1). A large proportion of the N deposited in throughfall at Camp Paivika occurred as fog drip, demonstrating the importance of fog deposition as an input source of N at this site. By comparison, bulk deposition rates in open areas were 5.1 and 5.4 kg ha-1 at Camp Paivika based on the two collector types, and 1.9 and 3.0 kg ha-1 at Barton Flats.

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Basal area growth trends were determined for ponderosa pine (Pinus ponderosa) in the Sierra Nevada, California, USA, to: (1) evaluate long term growth patterns, and (2) determine if there has been any recent change in the frequency of growth changes outside the expected range of natural variability. Ponderosa pine was sampled in 56 stands with the sample divided equally between sites with and without documentation of symptomatic ozone injury. Basal area increment growth was calculated, temporal growth patterns were evaluated for each tree using time series analysis techniques, and changes in growth trends were summarized for each site by decade. There were several regional growth trends during this century, including a large number of growth decreases in the 1920s and a large number of increases in the 1930s. Many trends were synchronous within stands but were less frequently synchronous between stands. There were significant growth reductions since 1950 in some stands in the southern Sierra. These growth reductions occurred in areas with the highest levels of ozone exposure and needle injury. There was no evidence, however, of significant numbers of recent growth reductions for the entire Sierra Nevada region. Some sites had growth changes possibly associated with stand dynamics, management practices, and pathogens.

Factors related to survival of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) 2 years after spring wildfires were evaluated at four sites in the Cascade Range. A logistic regression model was developed to estimate postfire survival. Crown scorch and three variables related to bole damage were significant in the regression model, with differences in response among sites attributed to differences in size class. The regression model predicted postfire response of live trees more accurately than that of dead trees, based on estimates of survival probability. Crown scorch was the most significant predictor of tree response, although the importance of additional variables indicated that evaluating bole damage greatly improves postfire survival estimates.

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