Long-term monitoring of western aspen--lessons learned.

Aspen woodland is an important ecosystem in the western United States. Aspen is currently declining in western mountains; stressors include conifer expansion due to fire suppression, drought, disease, heavy wildlife and livestock use, and human development. Forecasting of tree species distributions under future climate scenarios predicts severe losses of western aspen within the next 50 years. As a result, aspen has been selected as one of 14 vital signs for long-term monitoring by the National Park Service Upper Columbia Basin Network. This article describes the development of a monitoring protocol for aspen including inventory mapping, selection of sampling locations, statistical considerations, a method for accounting for spatial dependence, field sampling strategies, and data management. We emphasize the importance of collecting pilot data for use in statistical power analysis and semi-variogram analysis prior to protocol implementation. Given the spatial and temporal variability within aspen stem size classes, we recommend implementing permanent plots that are distributed spatially within and among stands. Because of our careful statistical design, we were able to detect change between sampling periods with desired confidence and power. Engaging a protocol development and implementation team with necessary and complementary knowledge and skills is critical for success. Besides the project leader, we engaged field sampling personnel, GIS specialists, statisticians, and a data management specialist. We underline the importance of frequent communication with park personnel and network coordinators.

Kinematic compensations as children reciprocally ascend and descend stairs with unilateral and bilateral solid AFOs.

The aim of this study was to identify the compensations made when a child with normal motor control ascends and descends stairs while wearing a solid AFO. Ten healthy children were asked to ascend and descend stairs with shoes, right and bilateral AFOs. Repeated measures ANOVA identified differences in selected kinematic parameters. Peak-to-peak excursion of pelvic rotation, pelvic obliquity, and hip ab/adduction increased with AFO use (P<0.05). Mean anterior pelvic tilt increased with AFO use (P<0.05). Compensations at the trunk and the pelvis facilitated limb advancement and clearance. This information may be helpful in developing strategies for training patients with motor planning difficulties.