Monitoring forest vegetation in the North Coast and Cascades Network: 2011 annual report

Acker, Steven; Boetsch, John; Bivin, Mignonne; Whiteaker, Lou; Cole, Carla

Late-successional, coniferous forest is critical for ecosystem function and biological conservation in the Pacific Northwest. Such forests are well-represented in the North Coast and Cascades Network (NCCN) of the National Park Service. As part of natural resource monitoring in the NCCN, we track trends in tree recruitment, growth, and mortality in forests in a range of environments in network parks. At the initiation of the project in 2008, we established 35 1-hectare plots in three parks (Mount Rainier (MORA), North Cascades (NOCA), Olympic (OLYM)), at elevations from near sea-level to almost 1800 m. We generated a spatially-balanced, random set of potential plot locations using the Generalized Randomized-Tesselation Stratified algorithm. Initial screening was conducted in the office using GIS to evaluate factors including access route safety and proximity to trails and roads. Potential plot locations that passed office screening were evaluated in the field for access safety, forest species composition and age, and other factors. Field activities in 2011 included plot evaluations at MORA and NOCA, plot establishment at Lewis and Clark National Historical Park (LEWI), MORA, and NOCA, and annual tree mortality checks at MORA, NOCA, and OLYM. We performed field evaluations of 6 potential plot locations at MORA and NOCA to address residual ambiguities from the project's early years. None of the points were found to be appropriate for permanent plots. We established 6 plots in 2011 in the 0-300 m elevation stratum (stratum 1) at LEWI. The climate in stratum 1 at LEWI is characterized by mild winters and high precipitation, similar to stratum 1 at OLYM. The plots in stratum 1 at LEWI were similar to stratum 1 at OLYM with respect to species composition and stand structure (i.e., predominantly Tsuga heterophylla and Picea sitchensis). However, hardwoods (particularly Rhamnus purshiana) were more numerous at LEWI than at OLYM. The plots at LEWI included 2 tree species not present in other plots in the network, including the first exotic species to be measured in the network’s permanent forest plots (Ilex aquifolium). In 2011 we also established one new plot at MORA and two new plots at NOCA. As in previous years, most of the newly-dead trees observed in 2011 died standing. Unlike previous years, a cause of death was identified for the majority of standing dead trees. Insects (usually Dendroctonus pseudotsugae) were by far the most commonly identified cause of death for the standing trees. With three consecutive years of annual observations of tree mortality, we performed the first evaluation of trends. Over two-thirds of plots showed no consistent trend in tree mortality. The remaining plots were split evenly, with half showing decreasing and half showing increasing trends.

Monitoring forest vegetation in the North Coast and Cascades Network: 2011 annual report

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