In the seventh funding cycle of Long-Term Ecological Research at the H.J. Andrews Experimental Forest (LTER7) we focused on the theme of "connectivity" as an intellectual prompt to help address our on-going central question: How do climate, natural disturbance, and land use as controlled by forest governance interact with biodiversity, hydrology, and carbon and nutrient dynamics?

In this funding cycle we maintained and utilized the continuity of our long-term experiments and measurement programs, some of which have been in place for more than 60 years, to help us understand connectivity over time. Over the six years of the grant (2014-2020) we made discoveries that have enhanced our understanding of our forest ecosystem and have important implications for ecosystem management. We learned that disturbance and human land use legacies can shape long-term ecological patterns and processes--from long-term forest development to nutrient dynamics to how the forest responds to new disturbances--demonstrating how intermingled social-ecological processes and feedbacks influence our understanding of disturbance ecology. We discovered that forest hydrology is not only impacted by regional climate oscillations but also by canopy structure, that past disturbance as well as climate impacts soil water storage varies with climate, and that past forest harvest has reduced late-summer streamflow. We found that our forest has massive carbon stores compared to other forest ecosystems and that management decisions can impact the ability of the forest to store carbon as well as protect species. We learned that, while the growth rate of slow-growing trees in second-growth forests were in sync with climate variability, older forest stands were desynchronized from climate variability. We also learned that variation in tree mortality can contribute to forest complexity (structure and composition) as well as to trends in ecosystem biomass diverging from trajectories predicted by theory and models. We saw how aquatic food webs and limiting factors in streams can by driven by reductions in forest canopy, how ongoing stream processes are influenced by the removal of in-stream wood, how the drought of 2015 temporarily reduced adult trout and salamander biomass in headwater streams, and how some fish and salamander species appear to be decreasing in body size in both old-growth and regenerating forests. We found that, while our forest has a high degree of temporal and spatial heterogeneity in moisture and temperature conditions, the response to microclimate variability is not consistent across trophic levels or taxa. We also discovered that a high prevalence of old-growth forest mediates the responses of forest bird populations to climate and may also mediate the effects of variation in climate on other taxa. The cold air drainage and pooling studied in past cycles demonstrated a moderating influence on under-canopy temperatures but in spatially heterogeneous ways that differ from previous conceptualizations of mountain landscape climate. Our human dimensions (social science, humanities, arts) examined how Andrews Forest research has impacted forest management in the Pacific Northwest, how the legacies of past institutions and shifting forest governance may impact the consequences of forest management and how it interacts with natural disturbances and land use, and how values and value judgments underpin forest management and conservation and the need to address such value assumptions transparently and systematically.

During this funding cycle we engaged in a variety of broader impacts efforts: including training and development of scientists and scientific knowledge of citizens at various levels, including K-12 teachers and students, undergraduate and graduate students, and early-career researchers; encouraging broadly multidisciplinary, collaborative research; forging stronger alliances between biophysical scientists and researchers in the various human dimensions; actively disseminating scientific knowledge through strong and long-standing science/management partnerships and contribution to adaptive management strategies; fostering many science/arts/humanities connections; and continuing to enhance our cyberinfrastructure at the H.J. Andrews Experimental Forest.

Last Modified: 12/16/2022
Modified by: Michael P Nelson