Alaskan deciduous forest stability
Datasets, code, and metadata associated with,
Hansen et al, (in press). An alternate vegetation type proves resilient and persists for decades following forest conversion in the North American boreal biome. Journal of Ecology
1. Changing climate and natural disturbances are increasingly causing forests to transition to alternate vegetation types (e.g., new tree species assemblages, grasslands). Determining whether and how these new vegetation types will persist is essential for forecasting earth system function during this century. However, long-term studies of past disturbance-induced forest conversion are rare, and future climates may not have a present day analog. Both limit the utility of empirical approaches for evaluating the fate of alternate vegetation types.
2. We conducted individual-based simulations to test how changing climate, disturbance, and biotic interactions shape the resilience of deciduous broadleaf forest, which has begun to replace spruce after severe wildfires in interior Alaska, USA.
3. Deciduous forest persisted in 86% of simulated stands and was especially resilient with fire return intervals of 50 years or shorter. However, when transitions to another vegetation type did occur, mixed forest was most common, particularly when fire return intervals were longer than 50 years and when seed source was distant. Recovery to spruce forest almost never occurred. Moose browsing and postfire drought also influenced outcomes, but effects were contingent on fire-regime characteristics. When fire return intervals were long and postfire seed sources were 500 m away or farther, moose browsing reduced deciduous sapling growth and survival, helping spruce better compete. Late 21st-century drought following short-interval fire was sufficient to occasionally cause conversion to nonforest.
4. Synthesis. Our analyses indicate that emerging postfire deciduous forest will almost certainly prove resilient for decades to centuries, which will shape biophysical and biogeochemical feedbacks to climate and alter subsequent disturbance. This paper offers a framework for quantifying the long-term resilience of alternate vegetation types following forest conversion and lends critical insights into the biotic and abiotic agents that are likely to underpin similar vegetation transitions across the North American boreal biome.
Please see attached file, table_descriptions_stability_project.csv for descriptions of each of the data tables in this project.